Abstract: The huge possibilities generated by the introduction of rapid prototyping techniques in the medical field has paved the way for collaborations between physicians and engineers to produce personalized medical devices, tailored to the specific anatomy of the patient. Specifically, in the field of autologous auricular reconstruction, i.e. the reconstruction of the external ear using the patient's costal cartilage, the authors worked towards the development of new patient-specific intraoperative devices, to support the surgeon during the procedure. The surgical guide design was then supported by the development of automated techniques for their modelling. In this work, a new hybrid technique for the CAD modelling of surgical guides is proposed. The idea is not to totally eliminate the intervention of the physician in defining the shape of the surgical guides, but rather to simplify their interaction with design tools. The proposed method is based on the straightforward adaption of a two-dimensional template developed by evaluating various auricular biometric parameters to approximate ear structure. The template is coupled to a parametric automatic procedure that generates the surgical guides' CAD model. The template was created outside of commercial CAD modeling software packages to make the procedure more accessible, and it is managed using a well-designed graphical user interface. With specialized questionnaires to evaluate the surgeon's satisfaction, the interface was put to the test, and the results were positive.

Keywords: 3D Modelling | Autologous Ear Reconstruction | CAD | Microtia | Personalized Medicine | Reverse Engineering

Abstract: The design of a sailing yacht is mostly based on the traditional design techniques of trial-and-error which takes time and requires iterative corrections to reach the final result. Moreover, several design teams with different and complementary expertise are required. If the standpoint is the one of the designs of a pleasure yacht, most of the activities can be solved through the related standards. While, concerning regatta’s yacht, more deep investigations become mandatory and intensive application of digital design instruments is now a common practice in modern yacht design. In this paper, a parametric procedure has been set up aimed to design and numerically compare sailing hulls performances. The hull shape design follows the classical approach based on the definition of the main curves frame and the generation of a parametric surface. Preliminary information about the hull resistance can be quickly obtained with a dedicated module of the software. Once a satisfactory shape has been modeled, detailed investigations can be automatically executed with commercial fluid dynamics software. The procedure has been successfully applied to the design of a new boat belonging to a specific class-called 1001VELAcup R3- which is two people racing dinghy designed according to a box rule with limitations on materials, dimensions and total sail area. The availability of experimental data suggested the numerical investigation about the influence of the hull geometry on the sailing performances.

Keywords: CAD modeling | Numerical investigation | Yacht design

Abstract: Design For Assembly (DFA) aims at improving product design facilitating assembly phases via the application of evaluation metrics and design guidelines. However, DFA analyses are usually performed manually and the adoption of supporting tool is poor. This paper investigates the application of algorithms allowing to extract from CAD assembly models the required data to perform automated DFA analyses, thus providing a tool to support designers’ everyday works. In particular, attributes from geometric feature recognition algorithms, solids properties and assembly parts’ semantics are leveraged and mapped to the parameters required to accomplish DFA evaluations. The proposed approach is illustrated on a 3D printer for home use. At first, a manual DFA analysis has been performed on the product identifying product BOM, components properties, assembly cycle and times according to models in the literature. Then, the CAD model of the printer has been processed with some geometric algorithms to verify the possibility to extract the required data to be used as input to the DFA analysis. The test case has demonstrated the feasibility of the approach, even if some design considerations and improvement directions still need the critical evaluation of the designer.

Keywords: Assembly semantics | Design For Assembly | Feature recognition | Part recognition

Abstract: In this work a Reverse Engineering based approach has been implemented aiming to reconstruct the 3D shape of a strongly damaged and no longer usable impeller of a submersible centrifugal pump. After obtaining the 3D model, new designs of the impeller were investigated in terms of structural stability and corrosion resistance by changing the geometry and the material. Obtained results show the used approach can be very useful both to reproduce, by Additive Manufacturing, no longer available spare parts, so allowing to extend the useful life of old machineries and to reduce costs resulting from plant shutdowns, but also to improve the performances of old designs, making use of different materials and new manufacturing processes.

Keywords: CAD | Centrifugal pump | Impeller | Modal analysis | Reverse Engineering

Abstract: Nowadays, 10–34% of patients undergone Total Knee Arthroplasty (TKA) continues to have pain and reduced mobility. New technologies in TKA have been developed to reproduce the native anatomy, respecting the natural joint line, by means of customized implants or following the kinematic alignment. In this context, the present research aims at defining a method to create customized implants. In particular, three different situations have been studied. The first condition is the healthy knee, that is used as reference for further analysis. For the second situation, an off-the-shelf prosthesis has been virtually implanted, following the kinematic joint line. In the third solution, a custom-made knee implant has been created. In all the three cases, FEA has been performed to study how load transmission and stability change after TKA. To reach the goal, high resolution Magnetic Resonance (MR) images of a healthy knee have been employed. Three-dimensional models of the knee have been reconstructed through a segmentation process, starting from DICOM images. Hence, the three situations have been studied. Distribution of pressure and stress are comparable in the two solutions, since they both maintain the natural joint line. Improving the kinematic function is crucial to increase patient satisfaction. According to the patient’s anatomy, the surgeon can choose between the standard and the personalized prosthesis. The studied customized approach allows to overcome the limits of conventional TKA since it permits to create geometries, which accommodate a variety of anatomical variations.

Keywords: 3D modeling | Customized knee implants | FEA | Kinematic alignment

Abstract: Tracheomalacia (TM) is a tracheal weakening that causes the cartilage structure to collapse during breathing. The term tracheobronchomalacia (TBM) is used when the bronchi are also implicated in the disease. This illness can be treated in a variety of methods, including the insertion of stents in the cartilage-restricted region. Stents are commercially available in numerous sizes (diameter and length), different shapes and materials. The shape of the stent is chosen based on where the disease is located, while the size is derived from measurements on CT images or by endoscopic investigations. This task is extremely critical for the patient's health since improper stent can have serious and even deadly repercussions for the patient. Therefore, it is necessary to choose a stent that fits the patient's anatomy as closely as possible. To this end, it is possible to employ a three-dimensional model of the investigated anatomy and choose the most suitable type of stent following measurements made on the model itself. In this work, a method to assist physicians in the choice of the stent to be used in TM or TBM patients, is proposed. By analyzing the tracheobronchial tree and measuring successive cross-sections along the centerline of the lumen, the automated procedure allows to localize the diseased area and to identify the optimal shape and size of the stent to be implanted. Four case studies of paediatric patients were performed and the results were validated by a team of physicians specialized in the treatment of upper and lower airways.

Keywords: 3D modelling | Airway obstruction | Reverse engineering | Stent

Abstract: When dealing with craniofacial impairments, restoring the morphological condition is as crucial as restoring the functional ones to avoid psychosocial disabilities for the patient. For this aim, the accurate location of the midsagittal plane is essential for performing reliable symmetry analyses and guiding effective surgery planning. To provide a fully automatic and landmark-independent approach, capable of providing a midsagittal plane for craniofacial skeleton even from anatomical models with high asymmetries, an innovative method, called MaWR-method, was developed by the authors in a previous work. This paper further investigates the MaWR-method by evaluating its capacity to produce a successful outcome even in the worst-case scenario that may be considered in maxillofacial surgery, namely panfacial fractures. In all the test cases considered in this work, the method proved robust and reliable in its original design. It provided a consistent result requiring no user involvement, even when dealing with extreme asymmetries because of extensive and complex fractures.

Keywords: Feature recognition | Mid-sagittal plane | Symmetry analysis | Symmetry plane detection

Abstract: The optimization of a galvanic process is a crucial task for many manufacturers in the field of electro-deposition industry. This is true for companies operating in the high fashion field, in which expensive materials are used and reducing material waste is crucial. In this paper, the estimation of the wet surface of small metal parts is treated. In fact, considering a single piece, the amount of material required to guarantee a desired plate thickness is directly proportional to its outer surface. Starting with a rapid overview on other methods to come up with this task, the attention in principally oriented to surface estimation by means of optical scanning. A preliminary test session has been carried out and two main issues arose. The first one is related to resolution and accuracy: due to pieces small dimensions and details, high performances are required to achieve valid results. The second and principal issue is related to the high reflectivity of pieces, even before electroplating. With the aim of avoiding the use of matting paint (which is difficult to remove), the attention has been focused on commercial solution dedicated to jewellery and dentistry fields. Three devices (based on white and blue LED structured light) have been tested on high reflective and specular pieces. From the analyses, only the one based on blue LED technology was able to retrieve high reflective surfaces without matting. Minor issues arose in case of specular surface. The device has been considered suitable for the task.

Keywords: 3D optical scanners | 3D reconstruction | Blue LED structured light | Galvanic | Reverse engineering

Abstract: The orbital walls and floor are common sites of facial bone fracture and may cause severe functional impairment. The complex geometry of the bony orbit makes anatomical reconstruction extremely challenging, with main issues related to the implant’s correct shaping, positioning, and orientation inside the orbital cavity. This study proposes an innovative medical device to place patient-specific implants in fractured eye sockets properly. The device must be used with the developed improved version of a tailored implant shaping mould. The design of the orbital implant positioner followed specific clinical and technical requirements and specifications investigated through the Quality Function Deployment method. The device has been conceived to be simple, economical, capable of managing deantigenated bones or titanium meshes for orbital floor and wall, and reusable multiple times. The positioner consists of two handles hinged together and adequately coupled by a spring to allow the grasping and placing of the implant. Positioner and mould have been manufactured in polyamide using the Selective Laser Sintering technique. The system accuracy assessment resulted in promising outcomes. The mould can precisely shape the implant with a lower than 0.1 mm deviation. The implant positioner can place the implant with a rotation angle around the orbital rim of barely 7.1° and 1.2 mm deviation in the mediolateral direction (no deviations in the anteroposterior and superior-inferior directions occur)

Keywords: Computer-aided design | Craniomaxillofacial surgery | Implant design | Medical devices | Rapid prototyping

Abstract: These authors presented an automatic computer-based method for morphological feature segmentation and recognition for thoracic and lumbar human vertebrae in a previous paper. The method analyses high-density discretized models by segmentation and recognition rules codifying the vertebra morphology information, which does not change between different subjects. The methodology has been demonstrated to be valid and repeatable in segmenting and recognizing morphological features of vertebrae. The proposed one gives repeatable and reproducible results concerning the traditional manual methods. Nonetheless, the method has been tested only on human lumbar and thoracic vertebrae without distinctive pathologies. This paper aims to extend this methodology for much wider use by analyzing single vertebrae affected by common defectiveness in archaeological and medical fields. The results of the experimentations, analyzed by a skilled anthropologist and radiologist, show that the method correctly segments the analyzed morphological features, also for thoracic and lumbar vertebrae with defectiveness: in particular, defects that alter the shape of features or the symmetry of the vertebra, determine the absence of a feature, or heavily change the spatial distribution of the anterior part respect to the posterior one, have been analyzed.

Keywords: 3D medical image analysis | Feature recognition | Thoracic and lumbar vertebrae analysis | Vertebrae analysis computer-based methods

Abstract: Digital human modeling and gait analysis are essential for improving hip replacement surgery (HRS). In this study, Convolution Neural Networks (CNN) are used as a machine learning method to extract the most accurate stick-model from videos captured on a simple camera to represent gait and body components. We developed and tested multiple approaches to create an equitable skeleton model from an image. This process consists of two main parts: defining the joint locations using a CNN network in different architectures, and defining the connections into the final skeletons. A CNN has been trained, validated, and tested using the OpenPose software, which combines two different networks that have been tested on three data-sets for learning and evaluation. The results were satisfactory, but MobileNetV1 was evaluated for optimization of OpenPose computations and definitions. Several hyper-parameters were investigated to provide better representations. As a result of utilizing OpenPose methodology in conjunction with heavily optimized network design and post-processing code, and implementing MobileNet, the proposed solution has provided improved accuracy ratios.

Keywords: 2D Joint profile | CNN | Deep Learning | skeleton feature extraction

Abstract: In the field of optical 3D scanning for healthcare applications, low-cost depth cameras can be efficiently used to capture geometry at video frame rates. However, the complete reconstruction of anatomical geometries remains challenging since different scans, collected from multiple viewpoints, must be aligned into a common reference frame. This paper proposes a fully automatic procedure to align scans of the upper limb patient’s anatomy. A 3D optical scanner, obtained by assembling three depth cameras, is used to collect upper limb acquisitions. A relevant dataset of key points on the hand and the forearm geometry is then determined and used to automatically obtain a rough 3D alignment of the different scans. Hand key points are identified through a neural network, which works on RGB images captured by the depth cameras; forearm key points are recognized by directly processing the point clouds through a specifically designed algorithm that evaluates the skeleton line of the forearm. The approach was tested on forearm acquisitions, and the results were compared to alternative alignment methodologies.

Keywords: 3D optical scanning | automatic point clouds alignment | depth cameras | upper limb anatomy

Abstract: Medical simulation tools have become increasingly popular in recent years for planning complex and non-routine surgeries. This applies also to autologous ear reconstruction, a procedure that is performed when patients have a complete or partial lack of the outer ear. On the basis of the contralateral ear, the physician sculpts a portion of costal cartilage that is then placed subcutaneously in the auricular region. Simulation tools can help the physician to familiarize with the specific geometries and shapes of the ear to be reconstructed. Making simulation tools requires the 3D acquisition of the ear, which can be done through optical scanners or diagnostic images (CT scan). This work focused on the development of a non-invasive, low-cost scanner for the acquisition of the outer ear. To this end, Intel RealSense D405 cameras were chosen, and a dedicated structure for the acquisition of ear anatomy was designed and manufactured, coupled with management software. The design of the scanner leveraged tests made with the Blender software for the optimization of the position and number of devices, while ensuring complete ear acquisition. Tests allowed the validation of the instrument both qualitatively, indicating the satisfaction of the medical staff in using the scanner, and quantitatively, measuring the deviation of the acquisition from a reference model obtained with professional scanners.

Keywords: 3D Ear Acquisition | CAD Modelling | Optical Scanner | Reverse Engineering

Abstract: The standard method of design and manufacturing customised orthoses is still very time-consuming due to their often very complex shape. Different authors have tried to solve this problem but, unfortunately, the proposed approaches cannot be easily used in clinical practice because they require substantial interaction among medical staff and engineers or technicians. The aim of this work is to present the framework of a new design approach that could allow clinicians to easily model a customised orthosis, without a skilled technician develops the entire procedure. In particular, an automatic process based on Generative Design has been implemented. The obtained results have demonstrated that the implemented algorithm is simple to use and could allow also not-skilled users to design customised orthoses.

Keywords: CAD | Customised orthosis | Generative design | Reverse engineering

Abstract: 3D reconstructed models are becoming more diffused daily, especially in the Cultural Heritage field. These geometric models are typically obtained from elaborating a 3D point cloud. A significant limit in using these methods is the realignment of different point clouds acquired from different acquisitions, particularly for those whose dimensions are millions of points. Although several methodologies have tried to propose a solution for this necessity, none of these seems to solve definitively the problems related to the realignment of large point clouds. This paper presents a new and innovative procedure for the fine registration of large point clouds. The method performs an alignment by using planar approximations of roof features, taking the roof’s extension into account. It looks particularly suitable for the alignment of large point clouds acquired in urban and archaeological environments. The proposed methodology is compared in terms of accuracy and time with a standard photogrammetric reconstruction based on Ground Control Points (GCPs) and other ones, aligned by the Iterative Closest Point method (ICP) and markers. The results evidence the excellent performance of the methodology, which could represent an alternative for aligning extensive photogrammetric reconstructions without the use of GCPs.

Keywords: multi-UAV scanning registration | particle swarm optimization | point cloud registration | shape features recognition

Abstract: The traditional manual method of analysis of ceramic finds involves expert operators in long and routine activities whose results depend on their subjectivity, specialization, and professional experience. This implies that the analysis of sherds is carried out using few data affected by high uncertainty. These limitations are even more clear with fragments with small axially symmetric portions whose elements of the investigation are not axially symmetric, such as handles, spouts, decorations. In this way both the axis of symmetry of the original object and the reference planes and/or axes of the characteristic dimensions of the elements are identified with such approximations as to compromise subsequent analyses and comparisons. To overcome these limitations, in this paper a new computer-based procedure is proposed. As a case study, the analysis fragments of jugs/bowls with trilobed spouts found in the site of Amiternum, coming from 12th-13th century contexts are considered; their analysis is fundamental to analyze the site where they were found since there is no archival documentation about their use.

Abstract: The sweep features of constant radius are particularly significant for the purposes of the historical-archaeological investigation and classification of ancient artifacts. The paper focuses on the automatic recognition of this specific class of features from triangulated 3D models experimentally acquired from cultural heritage objects. This is not a trivial problem. The ancient artifacts, although repeatable, are unique handmade pieces with a geometry commonly characterized by complex and non-analytical shapes. Their surfaces are also usually damaged and worn, so that the related geometric properties are altered or lost. The methodology proposed here is inspired by the one previously developed by the authors for the automatic segmentation of fillets, rounds and grooves from high-density triangulated models of mechanical components. The paper, in particular, focuses on the aspects of this methodology that must be tuned to allow the recognition of the sweep features of constant radius from archaeological finds. The methodology has been implemented and finally applied to an archaeological find acquired by a laser scanner.

Keywords: 3D archaeology | 3D digital models | Computer methods in archaeology | Feature recognition | Laser scanning

Abstract: Total Knee Arthroplasty (TKA) is a widely performed surgical procedure, which is advised to treat knee osteoarthritis. However, the literature reported that 25% of the patients are unsatisfied by the functional outcomes after the intervention. The main causes seem to be the prosthesis malalignment and the anatomical mismatch between the prosthetic components and the different people anatomy. Even if there exist several commercial solutions, whose aim has always been to provide a reliable prosthesis with high survivorship, the most recent scientific literature is focusing its aim to improving the patients’ clinical outcome, kinematics and satisfaction. For this reason, three approaches have been experimented and then discussed with an orthopedic surgeon. Open-source software applications for 3D modelling have been exploited, such as 3D Slicer and Meshmixer. Starting from medical images, through the segmentation process, the 3D model of the knee has been reconstructed. For the first approach, standard off-the-shelf prosthesis have been used for the virtual planning of the intervention. To overcome the limits of this method, two more customized approaches have been experimented. The first one is based on the patient-specific resurfacing prosthesis that fits the patient’s anatomy, preserving the femur and maintaining the natural joint line. The third approach allows to create a customized prosthesis, that is a compromise between the two previous methods. Among the three previous procedures, the most suitable one can be chosen according to the patient’s anatomy, knee size and articular cartilage damage.

Keywords: 3D modelling | Customized knee prosthesis | Total knee arthroplasty planning

Abstract: Emerging production technologies, in particular Additive Manufacturing (AM), nowadays are extremely suitable for creating highly complex products, tending towards the concept of ‘complexity for free’, which is often associated with AM. However, there are no adequate guidelines to provide decision support for the correct selection of the most economically appropriate technology. Indeed, from literature it has been highlighted the need to develop a technology selection methodology based no longer on production volume but on product complexity. This paper investigates this need by presenting an approach to determine the geometrical (or shape) complexity index of a part, which, combined with the assembly complexity, represents the driver for helping to decide the best production technology (traditional or additive). The geometrical complexity index has been determined based on complexity judgments, provided by CAD modelling experts, for a sample of CAD models. In this way, it has been possible to define a preliminary complexity index model, strictly linked to the CAD model information. The results showed that the geometrical complexity metrics from the literature, if individually considered, are not comprehensive. However, a combination of them makes it possible to obtain an index that best reflects the subjective judgement of the experts. In addition, by combining the geometrical and assembly complexity with a cost analysis it is possible to obtain convenience zones for better selecting the production technology.

Keywords: CAD | Geometrical complexity | Survey | Technology selection

Abstract: A Cayley map for the special Euclidean group SE(3) is introduced to relate, for a soft continuum robot, the Lie algebra of internal deformations with the Lie group of rigid–body motions. This Cayley map is used for approximated and exact kinematic shape reconstruction of soft continuum robots, under the hypothesis of constant deformations. This map could be used for deriving computationally efficient interpolation schemes for soft robots, since it does not involve transcendental functions as those introduced by the exponential parametrization of soft robot kinematics.

Keywords: Cayley transform | Differential geometry | Kinematics | Soft robotics

Abstract: Today it is more and more mandatory for all commercial companies to comply with the principles and methodologies of Industry 4.0 and to achieve the related capabilities protecting their competitiveness and taking a leading-edge position on market as regards technologies. Specifically, the whole production and sale system must achieve the fundamental characteristics of Industry 4.0 approach, but specially the manufacturing companies must also change and update their management procedures, internal organization, resource training, assets and all production process to keep safe their current business capacities. This evolution process is even more critical for Small and Medium Enterprises (SME), that traditionally tend to be conservative and to protect their way of operation, usually characterized by a low level of automation. The work presented focuses on the design and integration of a semi-automatic welding cell of train bolster in a SME which is currently realizing a project aimed to the acquisition of Industry 4.0 capabilities, with special focus on manufacturing processes. Among them, one of the most important is the production of welded-steel critical structures, that the Company supplies to prime manufacturer of railway rolling stock systems. The experience gained during the activity, the criticalities due to the integration processes and the adopted design methodologies are here described. The work has been carried out consistently with the Systems Engineering principles, starting from the requirements elicitation and analysis to the systematic approach for the design and integration activities.

Keywords: CAD | Design methodologies | Industry 4.0 | Internet of things (IoT) | Systems engineering | Welding process

Abstract: In radiotherapy, the treatment of skin tumors requires the application of tissue-equivalent devices in order to avoid the skin-sparing effect, and thus maximize and equalize the dose on the target. In the common clinical practice these devices, called bolus, are standard pads that do not perfectly adapt to the geometry of the patient generating empty spaces at the skin-bolus interface. This phenomenon hinders an efficient planning of the dose to be administered due to the non-adherence and the unpredictability of the position of the air gaps. In this work a workflow for the production of patient-specific bolus in Ecoflex® 00–10 silicone rubber (soft, biocompatible and sterilizable material) is proposed. The process exploits modern Reverse Engineering and Additive Manufacturing technologies to guarantee an accurate compliance with the involved geometries. Significant improvement, with respect to flat boluses, in the adhesion of the medical device to the anatomical region were found through in-vitro testing using replicas of the involved anatomy. Repeatability tests of the positioning performed on the customized bolus led to satisfying results demonstrating the possibility of accurate and predictable treatment planning.

Keywords: CAD modeling | Custom bolus | Molding | Radiotherapy

Abstract: In the Cultural Heritage field, the choice of materials and exhibit structures is essential to properly house and support artifacts without causing damage or deterioration. This problem is even more evident in the case of finds made of stone for which, due to their weight, a proper selection and dimensioning of the relative supports is required. In fact, without adequate support, this can result in stress concentrations that could compromise the artifact's state of conservation. As a consequence, more often such exhibition supports are customized items, that are designed and manufactured to meet specific functional and artistic setup needs. In this context, the paper presents a design approach that combines topology optimization and additive manufacturing techniques to develop customized support structures which undertake the twofold purpose of preserving the artifact and making it available for the exhibition in the museum. The proposed approach has been assessed through the case study of a sandstone Ionic capital hosted in the Brettii & Enotri Museum in Cosenza (Italy). The proposed approach is therefore meant as a guideline for the design of customized exhibit supports especially in the case of sandstone artifacts with a complex shape or a conservation condition that requires specific attention.

Keywords: Additive manufacturing | Cultural heritage | Design methods | Exhibit supports | Photogrammetry | Topology optimization

Abstract: The diffusion of Fab Labs and the continuous development of Additive Manufacturing technologies are undoubtedly two relevant phenomena nowadays. The former fuels the latter and vice versa, but their mutual relationship has not been systematically explored so far. This paper presents an exploratory study based on a survey, in which various aspects of the use of 3D printers in Fab Labs are investigated. The results show how different scales of Fab Labs are present in terms of investments made in 3D printing, as well as work purposes are not negligible for many attendees. In addition, the outcomes of the survey show that 3D printers are considered easy to use, as well as manufactured parts are deemed satisfactory. Despite this, there are still some barriers to boosting the market of domestic 3D printers for Fab Lab visitors.

Keywords: 3D printers | CAD | Design for Additive Manufacturing | Fab Labs | Skills

Abstract: Within the literature concerning modern machine learning techniques applied to the medical field, there is a growing interest in the application of these technologies to the nephrological area, espe-cially regarding the study of renal pathologies, because they are very common and widespread in our society, afflicting a high percentage of the population and leading to various complications, up to death in some cases. For these reasons, the authors have considered it appropriate to collect, using one of the major bibliographic databases available, and analyze the studies carried out until February 2022 on the use of machine learning techniques in the nephrological field, grouping them according to the addressed pathologies: renal masses, acute kidney injury, chronic kidney disease, kidney stone, glomerular disease, kidney transplant, and others less widespread. Of a total of 224 studies, 59 were analyzed according to inclusion and exclusion criteria in this review, considering the method used and the type of data availa-ble. Based on the study conducted, it is possible to see a growing trend and interest in the use of machine learning applications in nephrology, becoming an additional tool for physicians, which can enable them to make more accurate and faster diagnoses, although there remains a major limitation given the diffi-culty in creating public databases that can be used by the scientific community to corroborate and even-tually make a positive contribution in this area.

Keywords: artificial intelligence | deep learning | machine learning | renal pathology

Abstract: The present paper presents the development of a novel procedure for the modeling of Surgical Cutting Guides (SCGs) exploiting an implicit modeling approach. As discussed in the text, this approach allows for a streamlined and efficient design of this type of medical device. A procedural approach based on the application of a series of a priori-known implicit modeling function allows the generation of personalized surgical guides starting from the i) patient’s anatomy and ii) clinical decisions made by the medical staff. The CAD procedure is detailed in the text; achieved results are discussed and compared with a traditional CAD modeling approach on three case studies.

Keywords: CAD | Implicit Modelling | Patient-Specific Instrument | Personalized Medical Device

Abstract: The panel method is a potential-flow numerical approach that shows valuable performances to solve aerodynamic problems in the preliminary design stages. It shows a lower computational effort compared with Computational Fluid Dynamics, wind tunnel tests or ‘on the field’ experiments. However, the 3D surface discretization in rectangular panels is tedious and must be often carried out manually from scratch. Moreover, the panel method can’t be used to compute the overall drag force due to strong assumptions. To solve these two challenging aspects, the authors propose a voxel-based fluid dynamic approach integrating its programmed functions within a panel method. Voxelization is used to automatically distribute coherently the panels along the external surface of a 3D model in an automated way. A parametric study is included to demonstrate how the voxel resolution affects the aerodynamic results and provide guidelines for future research. Overall drag is estimated using corrections for both the skin friction and the form drag sources. The Ahmed body case study is included and demonstrates a good agreement between the voxel-based fluid dynamics approach and the literature benchmarking values, but with lower computational efforts. Further studies involving more complex shapes should be performed to better understand the performances and limitations of the approach.

Keywords: Ahmed body | Automotive | CAD | Conceptual Design | Panel method | Voxelization

Abstract: Mitral regurgitation is a common valvular disorder. Transcatheter edge-to-edge repair (TEER) is a minimally invasive technique which involves holding together the middle segments of the mitral valve leaflets, thereby reducing regurgitation. To date, MitraClip™ is the only Food and Drug Administration (FDA)-approved device for TEER. The MitraClip procedure is technically challenging, characterised by a steep learning curve. Training is generally performed on simplified models, which do not emphasise anatomical features, realistic materials, or procedural scenarios. The aim of this study is to propose a novel, 3D printed simulator, with a major focus on reproducing the anatomy and plasticity of all areas of the heart involved and specifically the ones of the mitral valve apparatus. A three-dimensional digital model of a heart was generated by segmenting computed tomography (CT). The model was subsequently modified for: (i) adding anatomical features not fully visible with CT; (ii) adapting the model to interact with the MitraClip procedural equipment; and (iii) ensuring modularity of the system. The model was manufactured with a Polyjet technology printer, with a differentiated material assignment among its portions. Polypropylene threads were stitched to replicate chordae tendineae. The proposed system was successfully tested with MitraClip equipment. The simulator was assessed to be feasible to practice in a realistic fashion, different procedural aspects including access, navigation, catheter steering, and leaflets grasping. In addition, the model was found to be compatible with clinical procedural imaging fluoroscopy equipment. Future studies will assess the effect of the proposed training system on improving TEER training.

Keywords: 3D printing | MitraClip procedure | mitral valve regurgitation | Polyjet | segmentation | simulation-based training | transcatheter edge-to-edge repair

Abstract: Medical image segmentation, especially for biological soft tissues, is an issue of great interest. The aim of this study is to evaluate the segmentation performance of a commercial and an open-source software, to segment aortic root and coronary arteries. 3D printing stereolithography technology was used to generate ground truth models, which were then re-acquired by means of a micro-CT scanner. Measurements from the printed and reconstructed models with both the software were compared, in order to evaluate the level of agreement. In the second phase of this study, Computational Fluid Dynamics (CFD) simulations were conducted, to compare the outputs between the models segmented with the two software. The goal was to understand how differences in the segmentation process propagate in CFD results. Results showed that both software guarantee satisfactory segmentation performance, with average geometrical differences between reconstructed and physical models in the order of a few percentage points. However, when we consider thin details, as a sharp stenotic region, the commercial validated software seems to be more accurate in replicating the real anatomy. We also realized how apparently negligible geometrical differences, varying the employed software, can turn into enormous variations of hemodynamic parameters, such as velocity and wall shear stress, which place in the centre the delicate role the segmentation process holds. This evidence is crucial in the biomedical field and especially in a coronary arteries study, where CFD simulations can be exploited as a starting point for surgery considerations.

Keywords: Additive manufacturing | CFD | Coronary arteries | Digital twins | Segmentation

Abstract: Additive manufacturing technologies are increasingly taking place in the medical field, enabling the creation of graspable patient-specific anatomical models. Because of their potentiality in improving the understanding of complex anatomies and their shown effectiveness for residents' training, devices testing and planning of innovative surgical interventions, 3D printed models have been incorporated also into cardiac surgery and interventional cardiology. To offer valid and reliable support, however, these printed models are often required to be flexible, with an adequate mechanical response, especially when they aim at replicating soft tissues. The goal of this paper is to provide a high-quality and robust template of a patient-specific whole heart model, obtained starting from a Computed Tomography dataset and exploiting a material jetting printer. Due to the significant shape complexity and the variability in compliance featuring the human heart, the selection of the materials have been diversified, taking into account different model wall thicknesses. Thanks to the capability of the material jetting technology, the 3D model of the heart has been printed with two different material assignments, designed to get highly realistic feedback and reduce the gap between the real heart and the printed ones. Eventually, an accuracy evaluation of the printed model has been performed, by means of a laser 3D scanner. Some further considerations about time and costs required to produce the model are part of the paper, together with a discussion about potential areas of improvement, from materials characterization to the need of speeding up and automating the segmentation procedure.

Keywords: Additive Manufacturing | Heart | Material Jetting | Patient-specific Anatomy | Segmentation

Abstract: Worldwide, stroke is the third cause of disability. The majority of people affected by this disease cannot perform activities of daily living. Bringing the therapy to the patients' home is complex, and in literature, there are still open challenges to face. Starting from therapists' and patients' needs, this paper describes a possible solution: HANDY, a rehabilitative active hand exoskeleton for post-stroke patients. With a desktop application, they perform three different types of exercises: passive, active and based on activities of daily living. They can also control the exoskeleton themselves in a serious-game approach with a leap motion controller. We evaluated our method with patients at the Villa Beretta rehabilitative center. Preliminary results from the session about comfort, usability and willingness to utilize the system are promising.

Keywords: Additive manufacturing | CAD modeling | Hand exoskeleton | Interactive applications | Stroke

Abstract: Analyzing an assembly and recognizing how the components can mate with each other in order to satisfy the functionality for which they have been designed is not a trivial task. Teaching such a problem to engineering students requires they are familiar with a set of components and how much larger or thin can be the errors intrinsically related to the technologies employed in their production. A set of steps are necessary to reasoning about the right identification of a chain of dimensions that influences a functionality. Then can be useful to have a table where collect the data, especially when the number of parts is relevant. The paper presents a new format for the table that can be used in all kinds of problems that may occur in design: analysis, analysis with constraints, and synthesis. The way how to employ such a table and the steps to solve each problem is discussed with known examples.

Keywords: Modeling | Tolerance analysis and synthesis | Tolerance stack-up

Abstract: The partial element equivalent circuit method is a well-known numerical technique that is used to solve Maxwell’s equations in their integral equation form. The application of the PEEC method to modeling domains with non-orthogonal three-dimensional geometries requires the computation of the interaction integrals to be performed numerically, thus slowing down the overall computation. This work presents a new technique that allows improving the computation of the interaction integrals of the PEEC method for non-orthogonal geometries under the quasi-static hypothesis. To this purpose, a voxelization approach that automatically decomposes non-orthogonal volumes in elementary parallelepipeds is used, allowing the implementation of closed-form formulas for the interaction integrals and completely avoiding numerical integration. The proposed approach is applied to three example problems exhibiting very good accuracy and excellent speed-up compared to the standard one using the numerical integration.

Keywords: Equivalent circuits | Geometry | Integral equations | Integral equations | Magnetic circuits | Magnetic domains | magnetic fields | magnetic material modeling | Mathematical models | partial element equivalent circuit (PEEC) method | Standards | voxel

Abstract: Target design methodologies (DfX) were developed to cope with specific engineering design issues such as cost-effectiveness, manufacturability, assemblability, maintainability, among others. However, DfX methodologies are undergoing the lack of real integration with 3D CAD systems. Their principles are currently applied downstream of the 3D modelling by following the well-known rules available from the literature and engineers’ know-how (tacit internal knowledge). This paper provides a method to formalize complex DfX engineering knowledge into explicit knowledge that can be reused for Advanced Engineering Informatics to aid designers and engineers in developing mechanical products. This research work wants to define a general method (ontology) able to couple DfX design guidelines (engineering knowledge) with geometrical product features of a product 3D model (engineering parametric data). A common layer for all DfX methods (horizontal) and dedicated layers for each DfX method (vertical) allow creating the suitable ontology for the systematic collection of the DfX rules considering each target. Moreover, the proposed framework is the first step for developing (future work) a software tool to assist engineers and designers during product development (3D CAD modelling). A design for assembly (DfA) case study shows how to collect assembly rules in the given framework. It demonstrates the applicability of the CAD-integrated DfX system in the mechanical design of a jig-crane. Several benefits are recognized: (i) systematic collection of DfA rules for informatics development, (ii) identification of assembly issues in the product development process, and (iii) reduction of effort and time during the design review.

Keywords: CAD | Design guidelines | Design rules | DfX | Engineering knowledge | Feature recognition | Ontology

Abstract: Design for Manufacturing and Assembly (DfMA) is a consolidated engineering activity that suffers a real integration with 3D CAD systems. DfMA principles are currently applied downstream of the 3D modelling, by following the well-known rules available from the literature and company’s know-how. The paper provides a method to acquire, elaborate and represent DfMA rules sets to aid designers and engineers in developing mechanical products. This research work wants to define a general method able to couple DfMA design guidelines (knowledge-based design) with geometrical product features available by the investigation of the 3D model. The analysis of the 3D CAD model allows to anticipate manufacturing issues and to control manufacturing cost during product design. Moreover, a framework to embed this approach within a 3D CAD system is presented for future development in a software tool. Two case studies, a simple casing made of six parts and a centrifugal pump made of sixty-eight parts, highlight how the proposed method allows easy deployment of this approach in DfMA projects. Several benefits are recognized: (i) anticipation of manufacturing and assembly issues, (ii) reduction of manufacturing and assembly cost and, (iii) reduction of effort and time required by designers during the product development process.

Keywords: cad | design guidelines | dfa | DfM | feature recognition

Abstract: This paper introduces a system that enable the collection of relevant data related to the emotional behavior and attention of both student and professor during exams. It exploits facial coding techniques to enable the collection of a large amount of data from the automatic analysis of students and professors faces using video analysis, advanced techniques for gaze tracking based on deep Learning, and technologies and the principles related to the Affective Computing branch derived from the research of Paul Ekman. It provides tools that facilitates the interpretation of the collected data by means of a dashboard. A preliminary experiment has been carried out to investigate whether such a system may help in assessing the evaluation setting and support reflection on the evaluation processes in the light of the different situations, so as to improve the adoption of inclusive approaches. Results suggest that information provided by the proposed system can be helpful in assessing the setting and the evaluation process.

Keywords: Affective computing | Deep learning | E-leaning | Emotion recognition | Gaze tracking

Abstract: The role of 3D virtual reconstruction of lost heritage artefacts is acquiring ever-greater importance, as a support for archaeological research and art history studies, as well as a vehicle for the cultural and evocative involvement of the end-user. The main risk of virtual reconstruction is the lack of a faithful restitution but, conversely, very often the artefact conservation state does not allow a complete 3D reconstruction. Therefore, 2D sources, both textual and iconographic, represent a precious integration and completion of the existing 3D sources. This paper proposes an operating systematic workflow to integrate retrieved 2D and 3D sources and assess their compatibility for the virtual reconstruction of lost heritage artefacts using and integrating 3D survey and digital modelling. As a case study, we virtually reconstructed the lost equestrian monument of Duke Francesco III d'Este, 7 m high, built in 1774 in Modena, Italy, by the sculptor Giovanni Antonio Cybei and completely destroyed a little over 20 years later during the revolutionary uprisings. Following the proposed workflow, we integrate data coming from: a still preserved preparatory stucco model, paintings and engravings showing the missing details of the 3D model, a series of urban views returning the proportion and positioning of the monument (statue, pedestal and base), a fragment of the right foot providing the statue size and the appearance of the original white Carrara marble. The final 3D digital model shows a faithful correspondence to the 2D sources and guarantees an effective user’s fruition thanks to dedicated virtual applications. Besides the scientific and cultural goal, we highlight the evocative role of this work, which has contributed to the restitution of a monument that is unknown to most citizens and visitors.

Keywords: 3D modelling | Close-range photogrammetry | Equestrian statue | Iconography | Virtual reconstruction

Abstract: Virtual or physical models of ancient machines are often used for museum exhibitions, documentaries and/or cinematographic works. Especially for high-fidelity models, complex activities are required, which actually lead the different stakeholders involved in the process to “design” an artifact (the model). As with any design process, the design of models of ancient machines can also benefit from the support of structured methods that guide the designers from the early “ideas” to the final design. This paper proposes a systematic approach specifically tailored for the interpretation and design of ancient machines, where a methodological tool is provided to manage both idea-generation and information-gathering activities. The method was applied to the design of a model of the delta wing conceived by Leonardo da Vinci (i.e., the glider represented in the Codex Madrid 1, Folio 64r), allowing to analyze and obtain an embodiment of the machine with the required fidelity level, thought to be realized in real scale.

Keywords: ancient machines | CAD | delta wing | design methods | design process | glider | Leonardo da Vinci | museum models | systematic design | technological heritage

Abstract: Introduction: In recent years, the scientific community focused on developing Computer-Aided Diagnosis (CAD) tools that could improve clinicians’ bone fractures diagnosis, primarily based on Convolutional Neural Networks (CNNs). However, the discerning accuracy of fractures’ subtypes was far from optimal. The aim of the study was 1) to evaluate a new CAD system based on Vision Transformers (ViT), a very recent and powerful deep learning technique, and 2) to assess whether clinicians’ diagnostic accuracy could be improved using this system. Materials and methods: 4207 manually annotated images were used and distributed, by following the AO/OTA classification, in different fracture types. The ViT architecture was used and compared with a classic CNN and a multistage architecture composed of successive CNNs. To demonstrate the reliability of this approach, (1) the attention maps were used to visualize the most relevant areas of the images, (2) the performance of a generic CNN and ViT was compared through unsupervised learning techniques, and (3) 11 clinicians were asked to evaluate and classify 150 proximal femur fractures’ images with and without the help of the ViT, then results were compared for potential improvement. Results: The ViT was able to predict 83% of the test images correctly. Precision, recall and F1-score were 0.77 (CI 0.64–0.90), 0.76 (CI 0.62–0.91) and 0.77 (CI 0.64–0.89), respectively. The clinicians’ diagnostic improvement was 29% (accuracy 97%; p 0.003) when supported by ViT's predictions, outperforming the algorithm alone. Conclusions: This paper showed the potential of Vision Transformers in bone fracture classification. For the first time, good results were obtained in sub-fractures classification, outperforming the state of the art. Accordingly, the assisted diagnosis yielded the best results, proving the effectiveness of collaborative work between neural networks and clinicians.

Keywords: CAD system | Deep learning | Femur fracture | Self-attention | Vision transformer

Abstract: Purpose: To evaluate the role of 3D models on positive surgical margin rate (PSM) rate in patients who underwent robot-assisted radical prostatectomy (RARP) compared to a no-3D control group. Secondarily, we evaluated the postoperative functional and oncological outcomes. Methods: Prospective study enrolling patients with localized prostate cancer (PCa) undergoing RARP with mp-MRI-based 3D model reconstruction, displayed in a cognitive or augmented-reality fashion, at our Centre from 01/2016 to 01/2020. A control no-3D group was extracted from the last two years of our Institutional RARP database. PSMr between the two groups was evaluated and multivariable linear regression (MLR) models were applied. Finally, Kaplan–Meier estimator was used to calculate biochemical recurrence at 12 months after the intervention. Results: 160 patients were enrolled in the 3D Group, while 640 were selected for the Control Group. A more conservative NS approach was registered in the 3D Group (full NS 20.6% vs 12.7%; intermediate NS 38.1% vs 38.0%; standard NS 41.2% vs 49.2%; p = 0.02). 3D Group patients had lower PSM rates (25 vs. 35.1%, p = 0.01). At MLR models, the availability of 3D technology (p = 0.005) and the absence of extracapsular extension (ECE, p = 0.004) at mp-MRI were independent predictors of lower PSMr. Moreover, 3D model represented a significant protective factor for PSM in patients with ECE or pT3 disease. Conclusion: The availability of 3D models during the intervention allows to modulate the NS approach, limiting the occurrence of PSM, especially in patients with ECE at mp-MRI or pT3 PCa.

Keywords: 3D modeling | Augmented reality | Prostate cancer | Robotic surgery | Surgical margins

Abstract: Exhausting manual labor is still predominant in the industrial context. It typically consists in manipulating heavy parts or working in non-ergonomic conditions. The resulting work-related musculoskeletal disorders are a major problem to tackle. The most-affected body section is the the lumbar spine. Recently, exoskeletons have been identified as a possible non-invasive solution to reduce the impact of low-back pain. State-of-the-art prototypes have been optimized to: follow unconstrained human kinematics, (partially) relieve the load on assisted joints, and allow anthropometric adaptation. Yet, this technology still has limited adoption. Manufacturing optimization may address the following limitations: bulky/heavy resulting designs, complex assembly and maintenance, high manufacturing costs, long procedures for adaptation and wearing, and psychological effects (e.g., cognitive load and usability). In this contribution, the aforementioned issues are tackled improving a previous low-back exoskeleton prototype. In particular, kinematic analysis, Finite-Element-Method, and topological optimization have been combined to obtain a lightweight prototype, testing different materials (Nylon, carbon-fiber reinforced PC/ABS, etc.). We applied both Design for Assembly and Design for Manufacturability. The resulting exoskeleton prototype is described in the paper, ready for end-user field tests.

Keywords: back-support; exoskeleton | backbone-based kinematics | industry4.0 | industry5.0 | materials selection | mechanical design | topological optimization

Abstract: Qualitative and quantitative analysis of surface defects on aluminum die-cast parts is important for both quality assurance and process monitoring. In addition to the functionality and durability of the parts, the appearance of a die-cast component can be of crucial importance during the inspection of incoming goods by customers in order to ensure their functionality. Nowadays, many of the detection operations of surface defects are performed by specialized operators, but this approach is far from being sustainable for high production rates. In this context, research has focused on machine vision systems for automatic defect detection based on artificial intelligence (AI) and artificial neural networks. However, several obstacles have so far hindered a full-scale application of these intelligent systems. Images of the aluminum surface can contain a large amount of noise due to surface reflectivity and, in addition, vibrations, improper/variable ambient lighting can make automatic analysis of surface defects, which usually have an irregular shape, very difficult. This led to combining the potential of 3D scanning and measuring systems with 2D machine vision as an acquisition technology to detect surface defects. Nevertheless, the two acquisition processes present strengths and weaknesses, which mostly depend on geometrical aspects of the parts to be detected. The present paper illustrates a first attempt to combine the mentioned 2D and 3D systems into an industrial production environment. The paper presents the developed system to allow multiple acquisitions and explains how these sources of information are fed to an AI system.

Keywords: Artificial intelligence | Deep learning | High-pressure die-casting | Machine vision systems | Quality control | Surface defects analysis

Abstract: Geometric and dimensional deviations are the main contributors on quality and cost of products. Specifically, the selection of tolerance types and the appropriate allowable range plays a central role for an effective development process. Nevertheless, the trade-off between expected performances and target costs requires skills and interaction of many areas of engineering design, especially in the early design phases. Despite many tolerance-cost optimization practices are proposed by the research community several limitations still hamper the industrial application: among them, data and parameters sharing, flexibility to application complexity, and integration of simulation tools are the main ones. Focusing on a systematic framework, an integrated modelling and simulation environment is required to take full advantage of the concurrent use of engineering software. The present paper contributes to this aim by suggesting a Computer-Aided framework that integrates Geometric Dimensioning and Tolerancing simulations and manufacturing cost estimations in a multi-disciplinary optimization environment. Advanced tools are the cornerstones of the suggested framework, enabling easy identification of the main operational steps and providing the automation of the optimization. To be validated and demonstrate the effective applicability, the framework has been applied for the tolerance-cost optimization of an archetypal case study of an automotive engine assembly. The simulation models have been integrated within the optimization, providing several configurations of tolerances from which identify the optimal one. The analysis of optimization results allows to assess the efficiency of the method, highlighting further improvements to extend its robustness, flexibility, and application range.

Keywords: Computer-Aided design | Cost estimation | Model-based definition | Multi-disciplinary optimization | Tolerance design

Abstract: Work-related musculoskeletal disorders are a very impactful problem, both socially and economically, in the manufacturing sector. To control their effect, standardised methods and technologies for ergonomic assessment have been developed. The main technologies used are inertial sensors and vision-based systems. The former are accurate and reliable, but invasive and not affordable for many companies. The latter use machine learning algorithms to detect human pose and assess ergonomic risks. In this paper, using data collecting by reproducing the working environment in LUBE, the major Italian kitchen manufacturer, we propose SPECTRE (Sensor-independent Parallel dEep ConvoluTional leaRning nEtwork): a fully sensor-independent learning model based on convolutional networks to classify postures in the workplace. This system assesses ergonomic risks in major body segments through Deep Learning with a minimal impact. SPECTRE’s performance is evaluated using established metrics for imbalanced data (precision, recall, F1-score and area under the precision-recall curve). Overall, SPECTRE shows good performance and, thanks to an agnostic explainable machine learning method, is able to extrapolate which patterns are significant in the input.

Keywords: Computer vision | Deep learning | Ergonomic risks | Human-centered manufacturing | Posture recognition | Work-related musculoskeletal disorders

Abstract: The study of the spine range of motion under given external load has been the object of many studies in literature, finalised to a better understanding of the spine biomechanics, its physiology, eventual pathologic conditions and possible rehabilitation strategies. However, the huge amount of experimental work performed so far cannot be straightforwardly analysed due to significant differences among loading set-ups. This work performs a meta-analysis of various boundary conditions in literature, focusing on the flexion/extension behaviour of the lumbar spine. The comparison among range of motions is performed virtually through a validated multibody model. Results clearly illustrated the effect of various boundary conditions which can be met in literature, so justifying differences of biomechanical behaviours reported by authors implementing different set-up: for example, a higher value of the follower load can indeed result in a stiffer behaviour; the application of force producing spurious moments results in an apparently more deformable behaviour, however the respective effects change at various segments along the spine due to its natural curvature. These outcomes are reported not only in qualitative, but also in quantitative terms. The numerical approach here followed to perform the meta-analysis is original and it proved to be effective thanks to the bypass of the natural variability among specimens which might completely or partially hinder the effect of some boundary conditions. In addition, it can provide very complete information since the behaviour of each functional spinal unit can be recorded. On the whole, the work provided an extensive review of lumbar spine loading in flexion/extension.

Keywords: Biomechanics | Follower load | Lumbar spine | Mechanical tests | Multibody | ROM

Abstract: Automated segmentation of brain tumors is a difficult procedure due to the variability and blurred boundary of the lesions. In this study, we propose an automated model based on Bendlet transform and improved Chan-Vese (CV) model for brain tumor segmentation. Since the Bendlet system is based on the principle of sparse approximation, Bendlet transform is applied to describe the images and map images to the feature space and, thereby, first obtain the feature set. This can help in effectively exploring the mapping relationship between brain lesions and normal tissues, and achieving multi-scale and multi-directional registration. Secondly, the SSIM region detection method is proposed to preliminarily locate the tumor region from three aspects of brightness, structure, and contrast. Finally, the CV model is solved by the Hermite-Shannon-Cosine wavelet homotopy method, and the boundary of the tumor region is more accurately delineated by the wavelet transform coefficient. We randomly selected some cross-sectional images to verify the effectiveness of the proposed algorithm and compared with CV, Ostu, K-FCM, and region growing segmentation methods. The experimental results showed that the proposed algorithm had higher segmentation accuracy and better stability.

Keywords: Bendlet system | feature set | image expression | segmentation | Shannon-cosine wavelet

Abstract: A 59-year-old woman was admitted to the emergency department for heart failure (HF), New York Heart Association (NYHA) IV, showing an anterior, evolved myocardial infarction (MI) with a wide apical left ventricular aneurysm (LVA), ejection fraction (EF) 24%, and global longitudinal strain (GLS) −5. 5% by echo. Cardiac magnetic resonance imaging (MRI) confirmed an apical LVA without thrombus, EF 20%, and a transmural delayed enhancement in the myocardium wall. Coronarography showed a three-vessel disease with occluded proximal left anterior descending (LAD) and proximal right coronary artery (RCA). Based on the cardiac CT scan, we decided to generate a three-dimensional (3D) print model of the heart, for better prediction of residual LV volumes. After LVA surgery plus complete functional revascularization, an optimal agreement was found between predicted and surgical residual LV end-diastolic (24.7 vs. 31.8 ml/m2) and end-systolic (54.1 vs. 69.4 ml/m2) volumes, with an improvement of NYHA class, from IV to I. The patient was discharged uneventfully and at 6- and 12-month follow-up, the NYHA class, and LV volumes were found unchanged. This is a second report describing the use of the 3D print model for the preoperative planning of surgical management of LVA; the first report was described by Jacobs et al. among three patients, one with a malignant tumor and the remaining two patients with LVA. This article focused on the use of the 3D print model to optimize surgical planning and individualize treatment of LVA associated with complete functional revascularization, leading to complete recovery of LV function with a favorable outcome.

Keywords: 3D printing model | CAD | heart failure | left ventricular aneurysm | surgical ventricular restoration

Abstract: In the last decades, the flourishing of Additive Manufacturing (AM) promoted innovative design solutions in many different sectors. Despite the numerous advantages of AM technology, there are still open challenges in the field. In Fused Deposition Modelling (FDM) structures the layer-by-layer manufacturing process induces anisotropy in the material properties of the structures. The correct characterization of the mechanical properties is fundamental in the design and development stages but at the same time difficult to achieve. The experimental approach can be extremely long and expensive. An alternative is the use of an accurate numerical approach and performing a Finite Element Analysis (FEA) of the geometry which is effectively printed. However, to the best of the authors' knowledge, there is not a common and well-established procedure to reconstruct the real geometry which is generated after the slicing process. In this paper, starting from the information provided by the G-CODE, an easy-to-use, and reproducible methodology to reconstruct the printed geometry is presented. The performance of the innovative approach is evaluated via qualitative observations by referring to several case studies. The results are thoroughly analysed, and future trends and research needs are highlighted.

Keywords: Additive Manufacturing | CAD | Fused Deposition Modelling | G-CODE

Abstract: Nowadays, web designers are forced to have an even deeper perception of how users approach their products in terms of user experience and usability. Remote Usability Testing (RUT) is the most appropriate tool to assess the usability of web platforms by measuring the level of user attention, satisfaction, and productivity. RUT does not require the physical presence of users and evaluators, but for this very reason makes data collection more difficult. To simplify data collection and analysis and help RUT moderators collect and analyze user’s data in a non-intrusive manner, this research work proposes a low-cost comprehensive framework based on Deep Learning algorithms. The proposed framework, called Miora, employs facial expression recognition, gaze recognition, and analytics algorithms to capture data about other information of interest for in-depth usability analysis, such as interactions with the analyzed software. It uses a comprehensive evaluation methodology to elicit information about usability metrics and presents the results in a series of graphs and statistics so that the moderator can intuitively analyze the different trends related to the KPI used as usability indicators. To demonstrate how the proposed framework could facilitate the collection of large amounts of data and enable moderators to conduct both remote formative and summative tests in a more efficient way than traditional lab-based usability testing, two case studies have been presented: the analysis of an online shop and of a management platform. Obtained results suggest that this framework can be employed in remote usability testing to conduct both formative and summative tests.

Keywords: affective computing | deep learning | gaze detection | remote usability testing | usability | usability assessment

Abstract: The current study aimed to propose a Deep Learning (DL) based framework to retrieve in real-time the position and the rotation of an object in need of maintenance from live video frames only. For testing the positioning performances, we focused on intervention on a generic Fused Deposition Modeling (FDM) 3D printer maintenance. Lastly, to demonstrate a possible Augmented Reality (AR) application that can be built on top of this, we discussed a specific case study using a Prusa i3 MKS FDM printer. This method was developed using a You Only Look Once (YOLOv3) network for object detection to locate the position of the FDM 3D printer and a subsequent Rotation Convolutional Neural Network (RotationCNN), trained on a dataset of artificial images, to predict the rotations’ parameters for attaching the 3D model. To train YOLOv3 we used an augmented dataset of 1653 real images, while to train the RotationCNN we utilized a dataset of 99.220 synthetic images, showing the FDM 3D Printer with different orientations, and fine-tuned it using 235 real images tagged manually. The YOLOv3 network obtained an AP (Average Precision) of 100% with Intersection Over Unit parameter of 0.5, while the RotationCNN showed a mean Geodesic Distance of 0.250 (σ = 0.210) and a mean accuracy to detect the correct rotation r of 0.619 (σ = 0.130), considering as acceptable the range [r − 10, r + 10]. We then evaluate the CAD system performances with 10 non-expert users: the average speed improved from 9.61 (σ = 1.53) to 5.30 (σ = 1.30) and the average number of actions to complete the task from 12.60 (σ = 2.15) to 11.00 (σ = 0.89). This work is a further step through the adoption of DL and AR in the assistance domain. In future works, we will overcome the limitations of this approach and develop a complete mobile CAD system that could be extended to any object that presents a 3D counterpart model.

Keywords: Augmented reality | CAD assistance | Deep learning | Neural network

Abstract: Recently, estimation of the visual saliency map in car driving scenarios has received significant research interests. Visual saliency perception includes the processing of specific parts of the visual driving scene in which the subject (car driver) pays more attention (specifically the parts whose gaze is focused). This work makes further contributions to video saliency research with application on the sustainable assisted driver technologies. Ad-hoc Semantic Fully Convolutional Deep Network embedding Gradient-Reversal domain adaptation layer has been implemented to process the video frames captured by a commercial low frame-rate automotive-grade camera device hosted outside the vehicle. A parallel motion-magnified visual-to-physio drowsiness assessment of the car driver will complete the proposed full automotive solution. The collected experimental results confirmed the effectiveness of the proposed solution.

Keywords: ADAS | Deep Learning | physio-signal | Saliency

Abstract: Automotive industry is making rapid progress in the development of next generation cars with higher levels of autonomy and intelligent assistance. Although the general advanced driver assistance system (ADAS) architecture is widely discussed, limited interaction between driver and these intelligent solutions sometimes make these approaches inefficient. For these reasons, the authors triggered an investigation about driver's feedback in relation to the assistance inputs provided by the ADAS technologies. In this context, the goal of this proposal is the design of an intelligent system that learns from the analysis of the car driver eyes saccadic movements, the correlated level of attention towards the salient driving scene. With this approach, we enabled a visual-feedback system which learns the driver eye's fixing dynamic associated to the analyzed driving scene. Through ad-hoc enhanced motion magnification technique, the authors were able to amplify the mentioned saccadic dynamics in order to allow a downstream deep classifier to associate this physiological behavior with the corresponding level of the driver attention. The collected performances (over 97%) confirmed the effectiveness of the proposed method.

Keywords: ADAS | Deep Learning | Driver eye saccadic movements | Motion Magnification

Abstract: Detection and identification of production defects in semiconductor industry is a key process to allow effective quality control of manufacturing. The advent of new technologies including Silicon and Silicon Carbide, highlights the necessity to have a robust detection system of wafer defects.The Electrical Wafer Sorting (EWS) stage based on defects map electrical analysis is suitable to spot anomalies and defect patterns in the wafer. This time consuming phase enables semiconductor companies to optimize and improve manufacturing process also through the usage of modern deep learning approaches. The proposed pipeline addresses the need to have a full-automatic wafer manufacturing defects identification system based on the EWS wafer map intelligent analysis and by using an approach based on a Deep Convolutional Neural Network combined with an unsupervised sub-system. The collected experimental results confirmed the robustness of the proposed approach.

Keywords: Deep learning | Machine learning | Pattern recognition | Silicon | Silicon Carbide

Abstract: Thanks to Laser Powder Bed Fusion (L-PBF) technology, SCALMALLOY® was the first aluminum powder material designed for Additive Manufacturing (AM), achieving a fine microstructure with high performance that is comparable to other cast materials. Despite the mechanical properties that can be achieved, there are some inherent factors that can impede components performance (i.e., surface roughness). Parts produced by L-PBF are usually characterized by rough “as-built” surfaces; hence, it is fundamental during the design phase to understand and consider how the quality of surfaces impacts on the part performance. This paper aims to provide a Computer-Aided Engineering (CAE) workflow to design components with different finishing regions in accordance with the functional distinction that exists among them. To achieve this goal, a comparison of the mechanical properties achieved for SCALMALLOY® specimens with and without post-processing is here assessed to fit proper material models for numerical simulation purposes. The material models, built with/from experimental data, are fit to functionally adapt the performance of 3D-printed objects inside CAE simulations like a Functionally Graded Material (FGM). A CAE design workflow is here applied to a case study, suitable to demonstrate how the methodology may support the integrated product–process design of structural parts reducing the cost of post-processing in AM. This approach may mitigate the performance decrease of “as-built” surfaces since the experimental results show a different fatigue endurance limit between the “as-built” and CNC machined specimens about of three times.

Keywords: CAD modeling | CAE analysis | Laser powder bed fusion | Mechanical properties | SCALMALLOY®

Abstract: Since every structure in the human body can vary, customization is important to choose the most appropriate medical option according to the patient. Total knee arthroplasty (TKA) is a surgical procedure for the knee replacement that has a high rate of patient's dissatisfaction. Indeed, conventional prostheses are based on anthropometric data that accommodate common knees. However, mismatch can occur due to anatomical variations among the individuals. Thanks to the advances in imaging techniques and 3D modeling, it is possible to create customized knee implants starting from medical images. In this context, the present research proposes a methodology to design a customized knee implant taking into account clinical (e.g., prosthesis alignment and surgical cuts) and technical parameters (e.g., materials) that have a direct impact on TKA performance and patient's satisfaction. Changing these parameters, different scenarios have been modeled and simulated to understand the most suitable combination. Finite element analysis (FEA) has been employed to simulate and compare the proposed customized models, changing the different clinical and technical parameters. Stress induced by different combinations of the parameters has been evaluated to choose the optimal solution among the eight proposed scenarios. The optimum is reached with a physiological alignment, with six femoral facets and the ultra-high molecular weight polyethylene (UHMWPE) tibial insert. The implant design maintains the natural joint line and allows preserving more bone. The material is the parameter that mostly influences the stress distribution.

Keywords: computer aided design | computer aided engineering | customized knee implant | femoral component optimization | finite element analysis | knowledge engineering | patient-specific knee prosthesis | total knee arthroplasty | virtual prototyping

Abstract: The 6D pose estimation of an object from an image is a central problem in many domains of Computer Vision (CV) and researchers have struggled with this issue for several years. Traditional pose estimation methods (1) leveraged on geometrical approaches, exploiting manually annotated local features, or (2) relied on 2D object representations from different points of view and their comparisons with the original image. The two methods mentioned above are also known as Feature-based and Template-based, respectively. With the diffusion of Deep Learning (DL), new Learning-based strategies have been introduced to achieve the 6D pose estimation, improving traditional methods by involving Convolutional Neural Networks (CNN). This review analyzed techniques belonging to different research fields and classified them into three main categories: Template-based methods, Feature-based methods, and Learning-Based methods. In recent years, the research mainly focused on Learning-based methods, which allow the training of a neural network tailored for a specific task. For this reason, most of the analyzed methods belong to this category, and they have been in turn classified into three sub-categories: Bounding box prediction and Perspective-n-Point (PnP) algorithm-based methods, Classification-based methods, and Regression-based methods. This review aims to provide a general overview of the latest 6D pose recovery methods to underline the pros and cons and highlight the best-performing techniques for each group. The main goal is to supply the readers with helpful guidelines for the implementation of performing applications even under challenging circumstances such as auto-occlusions, symmetries, occlusions between multiple objects, and bad lighting conditions.

Keywords: 6D position estimation | Computer vision | Deep learning | RGB Input

Abstract: Additive manufacturing technologies allow for the direct fabrication of 3D scaffolds with improved properties for tissue regeneration. In this scenario, design strategies and 3D fiber deposition technique are considered to develop advanced scaffolds with different lay-down patterns, tailored mechanical and biological properties. 3D poly(ε-caprolactone) scaffolds are manufactured and surface-modified (i.e., aminolysis). The effect of surface modification on the mechanical and biological performances of the designed 3D scaffolds is assessed.

Keywords: computer-aided design | design for additive manufacturing | mechanical analysis | scaffold design

Abstract: Light-activated resins and composites are used in conjunction with a light curing unit and allow an on-demand process of polymerization. These kinds of materials usually represent the most popular choice in the restorative dental practice. Some works have already highlighted contemporary tendencies in the use of nondegradable scaffolds and mesenchymal stem cells in regenerative medicine. Accordingly, the aim of the current research is to develop 3D porous and light-activated composite structures with optimized functional properties. Preliminary mechanical and biological tests are carried out.

Keywords: composite structure design | computer-aided design | design for photo-curing 3D printing | mechanical and functional properties

Abstract: The paradigm of Industry 4.0 allows to increase the efficiency and effectiveness of the production. Companies that will implement advanced solutions in production systems will increase their level of competitiveness and will be able reach high market shares. The present paper is focused on the development of advanced digital solutions to be implemented on a close power loop test bench designed to test high power transmissions for naval unit. In particular, the test configuration consists of a back-to-back connection between two identical mechanical reducers. Since the efficiency of these systems are very high, it is not necessary to use large electric motors, thus managing to contain the operating costs of the testing phase. The particular test bench allows to size the electric motor simply based on the dissipated power by the kinematic mechanisms. By means of suitable sensors installed on the test bench it is possible to extrapolate countless technical data. The implementation of Industry 4.0 enabling technologies allows to evaluate the increase in efficiency compared to traditional systems in terms of reduction of noise and vibrations, efficiency of lubrication, reduction of consumption, installation and maintenance cost of the entire system.

Keywords: Cad modeling | digital transformation | Experimental tests | Industry 4.0 | Internet of things | Shipyard 4.0 | Sustainability | Test bench

Abstract: Background and objective: Because of the three-dimensional distribution of morphological features of human vertebrae and the whole spine, in recent years, to make more precise diagnoses and to design optimized surgical procedures, new protocols have been proposed based on analysing their three-dimensional (3D) models. In the related literature, processes of segmentation and morphological features recognition are essentially performed by a skilled operator that selects the interesting areas. So, being affected by the preparation and experience of the operator, this produces an evaluation that is poorly reproducible and repeatable for the uncertainties of a typical manual measurement process. Methods: To overcome this limitation, in this paper a new automatic method is proposed for feature segmentation and recognition of human vertebrae. The proposed computer-based method, starting from 3D high density discretized models of thoracic and lumbar vertebrae, automatically performs both the semantic and geometric segmentation of their morphological features. The segmentation and recognition rules codify some important definitions used in the traditional manual method, considering all the vertebra morphology information that is invariant inter-subject. Results: The automatic method proposed here is verified by analysing many real vertebrae, both acquired using a 3D scanner and coming from Computerized Tomography (CT) scans. The obtained results are critically discussed and compared with the traditional manual methods for vertebra analysis. The method has proven to be robust and reliable in the segmentation and recognition of morphological features of vertebrae. Furthermore, the proposed automatic method avoids the blurring of quantitative parameters get from vertebrae, resulting from poor repeatability and reproducibility of manual methods used in the state-of-the-art. Conclusions: Starting from the automatic segmentation and recognition here proposed, it is possible to automatically calculate the parameters of thoracic or lumbar vertebrae used in archaeology, medicine, or biomechanics or define their new ones.

Keywords: 3D medical image analysis | Computer methods for vertebra analysis | Shape segmentation | Thoracic and lumbar vertebrae | Three-dimensional measurement

Abstract: Design process is usually based on past experiences and best practises which compose the company know-how. The challenge is to identify common patterns in the design solutions generated for different design problems. The present paper focuses on the identification of product patterns by using a graph-based approach. It deals with the designing of automotive gearboxes and with the development of an approach and a software tool aimed to support preliminary design and CAD modelling activities in gearbox designing. The approach is applied to two different architectures of manual transverse gearboxes characterized by two and three shafts. It aims at the identification of common design features through the detection of the directed graphs matching. A Matlab software tool for gearbox preliminary design is implemented according to the detected common features. The proposed approach and the developed software tool provide an effective way to keep and re-use company know-how, especially in the context of large automotive companies.

Keywords: CAD modelling | Graph theory | Graphical user interfaces | KBE | Product pattern

Abstract: Many industrial sectors face increasing production demands and the need to reduce costs, without compromising the quality. The use of robotics and automation has grown significantly in recent years, but versatile robotic manipulators are still not commonly used in small factories. Beside of the investments required to enable efficient and profitable use of robot technology, the efforts needed to program robots are only economically viable in case of large lot sizes. Generating robot programs for specific manufacturing tasks still relies on programming trajectory waypoints by hand. The use of virtual simulation software and the availability of the specimen digital models can facilitate robot programming. Nevertheless, in many cases, the virtual models are not available or there are excessive differences between virtual and real setups, leading to inaccurate robot programs and time-consuming manual corrections. Previous works have demonstrated the use of robot-manipulated optical sensors to map the geometry of samples. However, the use of simple user-defined robot paths, which are not optimized for a specific part geometry, typically causes some areas of the samples to not be mapped with the required level of accuracy or to not be sampled at all by the optical sensor. This work presents an autonomous framework to enable adaptive surface mapping, without any previous knowledge of the part geometry being transferred to the system. The novelty of this work lies in enabling the capability of mapping a part surface at the required level of sampling density, whilst minimizing the number of necessary view poses. Its development has also led to an efficient method of point cloud down-sampling and merging. The article gives an overview of the related work in the field, a detailed description of the proposed framework and a proof of its functionality through both simulated and experimental evidences.

Keywords: 3D reconstruction | Adaptive mapping | Inspection | Metrology | Robotics | View planning

Abstract: The aim of this work is to implement a new process for the design and production of orthopaedic devices to realize entirely by Additive Manufacturing (AM). In particular, a generative algorithm for parametric modelling of flexible structures to use in orthopaedic devices has been developed. The developed modelling algorithm has been applied to a case study based on the design and production of a customized elbow orthosis made by Selective Laser Sintering. The results obtained have demonstrated that the developed algorithm overcomes many drawbacks typical of traditional CAD modelling approaches. FEM simulations have been also performed to validate the design of the orthosis. The new modelling algorithm allows designers to model flexible structures with no deformations or mismatches and to create parametric CAD models to use for the production of orthopaedic devices through AM technologies.

Keywords: Additive Manufacturing | Additively manufactured textiles | CAD modelling | Elbow orthosis | Generative algorithms

Abstract: In this paper, a tool able to support the sailing yacht designer during the early stage of the design process has been developed. Cubic Rational Bézier curves have been selected to describe the main curves defining the hull of a sailing yacht. The adopted approach is based upon the definition of a set of parameters, say the length of waterline, the beam of the waterline, canoe body draft and some dimensionless coefficients according to the traditional way of the yacht designer. Some geometrical constraints imposed on the curves (e.g., continuity, endpoint angles, curvature) have been conceived aimed to avoid unreasonable shapes. These curves can be imported into any commercial Computer Aided Design (CAD) software and used as a frame to fit with a surface. The resistance of the hull can be calculated and plotted in order to have a real time estimation of the performances. The algorithm and the related Graphical User Interface (GUI) have been written in Visual Basic for Excel. To test the usability and the precision of the tool, two existing sailboats with different characteristics have been successfully replicated and a new design, taking advantages of both the hulls, has been developed. The new design shows good performances in terms of resistance values in a wide range of Froude numbers with respect to the original hulls.

Keywords: CAD | Excel | Rational Bézier curves | Sailing yacht design | VBA | VPP

Abstract: In this paper, a tool able to support the sailing yacht designer during the early stage of the design process has been developed. Quadratic and cubic Rational Bézier curves have been selected to describe the main curves defining the hull of a sailing yacht. The adopted approach is based upon the definition of a set of parameters, say the length of water line, the beam of the waterline, canoe body draft and some dimensionless coefficients according to the traditional way of the yacht designer. Some geometrical constraints imposed on the curves (e.g. continuity, endpoint angles) have been conceived aimed to avoid unreasonable shapes. These curves can be imported in any commercial CAD software and used as a frame to fit with a surface. The algorithm and the related Graphical User Interface (GUI) have been written in Visual Basic for Excel. To test the usability and the precision of the tool, two sailboats with different characteristics have been replicated. The rebuilt version of the hulls is very close to the original ones both in terms of shape and dimensionless coefficients.

Keywords: CAD | Rational Bézier curves | Sailing yacht design

Abstract: Currently, there is a growing interest of industries in applying additive manufacturing (AM) technology for generating objects with high geometrical complexity and low weight, ensuring good performance, comparable to those ones of products realized by means of traditional techniques. Anyway, it is still usual to realize AM products without focusing on the morphology of the object, hence without exploiting all the advantages of the technique. Indeed, since the several suitable AM technologies, it should be useful to know the functional characteristics of the component for the best choice of the appropriate one and its constructive complexity. In this regard, the 3D modeling strategy is extremely crucial for a proper realization of AM products. The paper deals with a study of the geometrical complexity of dashboard components of a car, based on several techniques for evaluating the geometric complexity. The latter is a fundamental element for estimating the feasibility of AM in terms of production costs and the benefits with respect to traditional molding. In detail, the study focuses on comparing several geometrical complexity evaluation techniques in order to identify the one that simplifies the calculation and better approximates the most used in literature.

Keywords: additive manufacturing | CAD | geometrical complexity

Abstract: This paper introduces a novel upper limb robotic exoskeleton designed to assist industrial operators in a wide range of manual repetitive tasks, such as tool handling and lifting/moving of heavy items. Due to its reduced size and high maneuverability, the proposed portable device may also be employed for rehabilitation purposes (e.g. as an aid for people with permanent neuromuscular diseases or post-stroke patients). Its primary function is to compensate the gravity loads acting on the human shoulder by means of a hybrid system consisting of four electric motors and three passive springs. The paper focuses on the exoskeleton mechanical design and virtual prototyping. After a preliminary review of the existent architectures and procedures aimed at defining the exoskeleton functional requirements, a detailed behavioral analysis is conducted using analytical and numerical approaches. The developed interactive model allows to simulate both kinematics and statics of the exoskeleton for every possible movement within the design workspace. To validate the model, the results have been compared with the ones achieved with a commercial multibody software for three different operator’s movements.

Keywords: Computer aided design | Gravity balancing | Robotic arm | Upper limb exoskeleton | Virtual prototyping

Abstract: Beam-based Compliant Mechanisms (CMs) are increasingly studied and implemented in precision engineering. Straight beams with uniform cross section are the basic modules in several design concepts, which can be deemed as standard CMs. Their behavioral analysis can be addressed with a large variety of techniques, including the Euler–Bernoulli beam theory, the Pseudo-Rigid Body (PRB) method, the beam constraint model and the discretization-based methods. This variety is unquestionably reduced when considering nonstandard CMs, namely design problems involving special geometries, such as curve/spline beams, variable section beams, nontrivial shapes and contact pairs. The 3D Finite Element Analysis (FEA) provides accurate results but its high computational cost makes it inappropriate for optimization purposes. This work compares the potentialities of computationally efficient modeling techniques (1D FEA, PRB method and chained-beam constraint model), focusing on their applicability in nonstandard planar problems. The cross-axis flexural pivot is used as a benchmark in this research due to its high configurable behavior and wide range of applications. In parallel, as an attempt to provide an easy-to-use environment for CM analysis and design, a multi-purpose tool comprising Matlab and a set of modern Computer-Aided Design/Engineering packages is presented. The framework can implement different solvers depending on the adopted behavioral models. Summary tables are reported to guide the designers in the selection of the most appropriate technique and software framework. Lastly, efficient design procedures that allow to configure nonstandard beam-based CMs with prescribed behavior are examined with two design examples.

Keywords: CAD/CAE software framework | Compliant Mechanisms | Cross-axis flexural pivot | Design methods | Shape optimization | Virtual Prototyping

Abstract: This paper reports about the design of a bio-inspired compliant wrist, whose mobility (i.e. ulnar-radial deviation and flexion-extension) has been realized by employing two pairs of contact-aided Cross-Axis Flexural Pivots (CAFPs), actuated via remotely-placed servo-motors and tendon transmissions. The human wrist behaves differently when deflecting in clockwise or anticlockwise direction, both in terms of maximum angular deflection and passive stiffness. The device proposed hereafter aims at mimicking such natural asymmetry, while withstanding unexpected external loads. In order to fulfill these requirements, two contacts are included: (i) a pure rolling contact (named passive contact), achieved via a cam mechanism guiding the CAFP deflection and ensuring the wrist resistance to compressive loads; (ii) a purposely shaped contact pair (named active contact), acting on one beam of the CAFP so as to increase its stiffness. The design procedures and tools specifically developed for the wrist optimization are described. In the first step, a CAFP shape optimization is performed, followed by the synthesis of the active contact pair. In the second step, the centrodes are computed and then used to generate the passive contact profiles. At last, the third step focuses on the definition of the tendons routing. To prove the validity of the numerical models, a physical prototype of the wrist is produced and tested. Direct comparisons between simulations and experiments confirm the efficacy of the proposed design method.

Keywords: CAD/CAE multi-software framework | Compliant mechanism | Cross-axis flexural pivot | Robotic wrist | Shape optimization | Virtual prototyping

Abstract: In the last decades, the popularity of video games has been increasing thanks to their unique ability to engage their audience and create empathy. Among them, serious games have additional purposes besides entertainment, such as learning and behaviour change. Serious games, in fact, have been successfully applied to different fields, including education, health, tourism, and cultural heritage. In this context, the paper describes a novel serious game developed for increasing awareness and promoting the Underwater Cultural Heritage (UCH). In particular, the paper focuses on the Dive in the Past Serious Game which allows users to simulate a virtual dive into the Mediterranean Sea to explore accurate and life-sized 3D reconstructions of underwater archaeological sites. The purpose of the game is twofold: to engage diver and non-diver tourists into a virtual interactive exploration of underwater sites through digital storytelling and challenges; to increase awareness and knowledge on Mediterranean UCH. This work has been carried out in the context of the MeDryDive project, an EU co-funded under the COSME Programme, which aims to create personalized dry dive experiences for the promotion of Mediterranean UCH sites as distinctive tourism destinations.

Keywords: 3D reconstruction | Mediterranean Sea | Serious game | Underwater archaeology | Underwater Cultural Heritage

Abstract: This paper presents the results of a survey carried out with students enrolled in the first two years of the BS in Engineering at three Italian university locations. The study is part of a wider range of methods, tools and aids for the improvement of teaching and learning of technical drawing at university level developed by the University of Brescia, Udine, and Cassino and Southern Lazio. In particular, this work analyses the results of questionnaires related to the basic technical drawing outcomes, taking inspiration from previous research work in this field. What emerges is a positive picture that shows students’ interest in 3D CAD modeling topics such as part or assembly construction, but also their interest in more traditional subjects like sketching and dimensioning.

Keywords: CAD | Engineering education | Students’ surveys | Technical drawing

Abstract: Colour and texture are two perceptual stimuli that determine, to a great extent, the appearance of objects, materials and scenes. The ability to process texture and colour is a fundamental skill in humans as well as in animals; therefore, reproducing such capacity in artificial (‘intelligent’) systems has attracted considerable research attention since the early 70s. Whereas the main approach to the problem was essentially theory-driven (‘hand-crafted’) up to not long ago, in recent years the focus has moved towards data-driven solutions (deep learning). In this overview we retrace the key ideas and methods that have accompanied the evolution of colour and texture analysis over the last five decades, from the ‘early years’ to convolutional networks. Specifically, we review geometric, differential, statistical and rank-based approaches. Advantages and disadvantages of traditional methods vs. deep learning are also critically discussed, including a perspective on which traditional methods have already been subsumed by deep learning or would be feasible to integrate in a data-driven approach.

Keywords: Colour | Deep learning | Texture | Visual recognition

Abstract: Background: Accurate segmentation of pulmonary nodules on computed tomography (CT) scans plays a crucial role in the evaluation and management of patients with suspicion of lung cancer (LC). When performed manually, not only the process requires highly skilled operators, but is also tiresome and time-consuming. To assist the physician in this task several automated and semi-automated methods have been proposed in the literature. In recent years, in particular, the appearance of deep learning has brought about major advances in the field. Methods: Twenty-four (12 conventional and 12 based on deep learning) semi-automated-'one-click'- methods for segmenting pulmonary nodules on CT were evaluated in this study. The experiments were carried out on two datasets: A proprietary one (383 images from a cohort of 111 patients) and a public one (259 images from a cohort of 100). All the patients had a positive transcript for suspect pulmonary nodules. Results: The methods based on deep learning clearly outperformed the conventional ones. The best performance [Sørensen-Dice coefficient (DSC)] in the two datasets was, respectively, 0.853 and 0.763 for the deep learning methods, and 0.761 and 0.704 for the traditional ones. Conclusions: Deep learning is a viable approach for semi-automated segmentation of pulmonary nodules on CT scans.

Keywords: Computed tomography (CT) | Deep learning | Lung cancer (LC) | Pulmonary nodules | Segmentation

Abstract: The valve train plays a major role in the performance of internal combustion engines by controlling the combustion process and it is therefore one of the key aspects for increasing the efficiency of combustion engines. Considering the dynamics, the spring force must be high enough to reliably close the valve preventing from seating bouncing due to surge modes after the valve closure. On the other side, the spring force should be kept as low as possible in order to reduce the engine friction losses and consequently the fuel consumption. In the high-performance engines, the valve springs have to be designed and optimized for sustaining higher stresses with compact dimensions leading to critical material and manufacturing processes. This requires a reduction of moving masses and a strong focus on design and process optimization of the coil springs for reducing the mechanical load and the friction losses at low engine speed. At the same time, valve train should be reliable at high engine speed. The calculation of stresses and contact forces for moving parts under dynamic load is essential for durability analysis. A method to calculate the contact of moving masses is described and proposed to justify valve motions experimental results. To fully understand the failure mechanism of test bed reliability trials, the dynamic stresses have been calculated modeling the real springs’ shape. The contact forces have been reproduced considering the coil clash effects and the dynamic behavior of the flexible spring.

Keywords: Coil clash | FEM | Multibody | Valve springs | Valve train

Abstract: BACKGROUND: One of the aspects that influences the sitting comfort is the distribution of the pressure applied to the skin by the seat surface. In the scientific literature, many studies show experimental activities in order to evaluate the influence of pressure distribution at the seat-human interface on the comfort evaluation. The main limitation in seat design is based on the difficulties to predict the contact pressures distribution without prototypes because of the complex interaction among body muscles, wearing, human's anthropometric characteristics, shape and materials of the seat. Moreover, the same human can assume different postures on the same seat, and different people, seated on the same chair, can assume different postures even if they have the same anthropometric percentile. OBJECTIVE: The aim of this study is to propose a mathematical model evaluating interaction loads between human segments and seat segments. METHOD: In this model, a human body represented by 8 segments is placed on a 6 segments seat with posture dependent on seat segments and on position of the coccyx on seat and feet on floor. Human segments can be configured in length and weight and friction between body and seat is considered. A model validation study based on an experimental comparison with contact pressures is also presented. RESULTS: The experiment showed that there is a remarkable recursion of some stress values of the articular joints of the pelvis, hip and knee. By imposing these values in the calculation model, it is possible to determine, for each chair configuration, which postures will be assumed by a person, and to make a preliminary assessment of the level of comfort possible.

Keywords: contact pressures | modelling | seat | Seating posture

Abstract: Driver inattention is the primary cause of vehicle accidents; hence, manufacturers have introduced systems to support the driver and improve safety; nonetheless, advanced driver assistance systems (ADAS) must be properly designed not to become a potential source of distraction for the driver due to the provided feedback. In the present study, an experiment involving auditory and haptic ADAS has been conducted involving 11 participants, whose attention has been monitored during their driving experience. An RGB-D camera has been used to acquire the drivers’ face data. Subsequently, these images have been analyzed using a deep learning-based approach, i.e., a convolutional neural network (CNN) specifically trained to perform facial expression recognition (FER). Analyses to assess possible relationships between these results and both ADAS activations and event occurrences, i.e., accidents, have been carried out. A correlation between attention and accidents emerged, whilst facial expressions and ADAS activations resulted to be not correlated, thus no evidence that the designed ADAS are a possible source of distraction has been found. In addition to the experimental results, the proposed approach has proved to be an effective tool to monitor the driver through the usage of non-invasive techniques.

Keywords: ADAS | CNN | DADA | Deep learning | Driver’s attention | RGB-D camera

Abstract: This paper describes a methodology to design and optimize a controllable pitch propeller suitable for small leisure ship boats. A proper range for design parameters has to be set by the user. An optimization based on the Particle Swarm Optimization algorithm is carried out to minimize a fitness function representing the engine’s fuel consumption. The OpenProp code has been integrated in the procedure to compute thrust and torque. Blade’s geometry and tables about pitch, thrust and consumption are the main output of the optimization process. A case study has been included to show how the procedure can be implemented in the design process. A case study shows that the procedure allows a designer to sketch a controllable pitch propeller with optimal efficiency; computational times are compatible with the design conceptual phase where several scenarios must be investigated to set the most suitable for the following detailed design. A drawback of this approach is given by the need for a quite skilled user in charge of defining the allowable ranges for design parameters, and the need for data about the engine and boat to be designed.

Keywords: CAD | Controllable pitch propeller | Design propeller | Particle swarm optimization

Abstract: Within the context of modern industries, additive manufacturing (AM) plays a critical role. Design for AM (DfAM) requires defining design actions related to the product's geometry under development. DfAM affects design choices such as the type of process, the material, the geometry, and the model's features. Knowledge-based engineering (KBE) is promising for integrating DfAM principles in the early phases of product development. Still, few limitations are noticed, such as the real interoperability between DfAM and 3D CAD systems, leading to the application of proper DfAM rules downstream of the 3D modeling. This paper aims to describe a method to formalize AM engineering knowledge used as a repository to develop a CAD-integrated decision support tool by acknowledging the current gap. The method uses, as input, geometrical data retrieved by the feature analysis of the 3D CAD model (feature recognition approach) and manufacturing information related to AM processes. The method will allow closing the gap between the design and production departments by creating a knowledge-based system. The outcome of this system does not concern the possibility of predicting the AM process parameters. The system will support engineers in delivering product designs compliant with AM processes. Based on this system, a CAD-integrated DfAM tool can be developed in the future.

Keywords: Additive manufacturing | Am | Cad | Design for additive manufacturing | Design rules | Design tool | Feature recognition | Knowledge-based system

Abstract: Medical images do not provide a natural visualization of 3D anatomical structures, while 3D digital models are able to solve this problem. Interesting applications based on these models can be found in the cardiovascular field. The generation of a good-quality anatomical model of the heart is one of the most complex tasks in this context. Its 3D representation has the potential to provide detailed spatial information concerning the heart’s structure, also offering the opportunity for further investigations if combined with additive manufacturing. When investigated, the adaption of printed models turned out to be beneficial in complex surgical procedure planning, for training, education and medical communication. In this paper, we will illustrate the difficulties that may be encountered in the workflow from a stack of Computed Tomography (CT) to the hand-held printed heart model. An important goal will consist in the realization of a heart model that can take into account real wall thickness variability. Stereolithography printing technology will be exploited with a commercial rigid resin. A flexible material will be tested too, but results will not be so satisfactory. As a preliminary validation of this kind of approach, print accuracy will be evaluated by directly comparing 3D scanner acquisitions to the original Standard Tessellation Language (STL) files.

Keywords: 3D printing | Heart model | Patient-specific modeling | Segmentation | Stereolithography

Abstract: Purpose: COVID-19 has spread rapidly worldwide since its initial appearance, creating the need for faster diagnostic methods and tools. Due to the high rate of false-negative RT-PCR tests, the role of chest CT examination has been investigated as an auxiliary procedure. The main goal of this work is to establish a well-defined strategy for 3D segmentation of the airways and lungs of COVID-19 positive patients from CT scans, including detected abnormalities. Their identification and the volumetric quantification could allow an easier classification in terms of gravity, extent and progression of the infection. Moreover, these 3D reconstructions can provide a high-impact tool to enhance awareness of the severity of COVID-19 pneumonia. Methods: Segmentation process was performed utilizing a proprietary software, starting from six different stacks of chest CT images of subjects with and without COVID-19. In this context, a comparison between manual and automatic segmentation methods of the respiratory system was conducted, to assess the potential value of both techniques, in terms of time consumption, required anatomical knowledge and branch detection, in healthy and pathological conditions. Results: High-quality 3D models were obtained. They can be utilized to assess the impact of the pathology, by volumetrically quantifying the extension of the affected areas. Indeed, based on the obtained reconstructions, an attempted classification for each patient in terms of the severity of the COVID-19 infection has been outlined. Conclusions: Automatic algorithms allowed for a substantial reduction in segmentation time. However, a great effort was required for the manual identification of COVID-19 CT manifestations. The developed automated procedure succeeded in obtaining sufficiently accurate models of the airways and the lungs of both healthy patients and subjects with confirmed COVID-19, in a reasonable time.

Keywords: COVID-19 | CT | Lungs | Respiratory system | Segmentation

Abstract: The study of CAD (computer aided design) modeling, design and manufacturing techniques has undergone a rapid growth over the past decades. In medicine, this development mainly concerned the dental and maxillofacial sectors. Significant progress has also been made in orthopedics with pre-operative CAD simulations, printing of bone models and production of patient-specific instruments. However, the traditional procedure that formulates the surgical plan based exclusively on two-dimensional images and interventions performed without the aid of specific instruments for the patient and is currently the most used surgical technique. The production of custom-made tools for the patient, in fact, is often expensive and its use is limited to a few hospitals. The purpose of this study is to show an innovative and cost-effective procedure aimed at prototyping a custom-made surgical guide for address the cubitus varus deformity on a pediatric patient. The cutting guides were obtained through an additive manufacturing process that starts from the 3D digital model of the patient’s bone and allows to design specific models using Creo Parametric. The result is a tool that adheres perfectly to the patient’s bone and guides the surgeon during the osteotomy procedure. The low cost of the methodology described makes it worth noticing by any health institution.

Keywords: 3D Printing | CAD Modeling | Cutting guides | Pediatric orthope-dics | Preoperative simulation | Surgery and diagnostics

Abstract: This paper presents a study based on Design for Disassembly (DfD) applied to a hydraulic pump through the Disassembly Geometry Contacting Graph (DGCG) methodology. DfD is today very important to reduce the disposal or maintenance costs foreseeable already in the planning phase. One of the key points in reducing costs is reducing time for disassemble each component. Because of that, the disassembly time was considered respect to other fundamental and optimizable characteristics such as: Disassembly costs, operations to be performed, quantity of material, etc. All the operations have been evaluated using the time measurement units (TMUs). The objective of the paper is to minimize the disassembly times required for an operator to separate each single component from the other. The study of accessibility, positioning, strength, and basic time led to a comparison between different disassembly methods in order to produce the optimal sequence. In the end, the validation of the sequence was carried out in an Augmented Reality (AR) environment in order to predict the manual disassembly understanding the possible issues without the need of building the components. Using AR, it was possible to look at the assembly during the design phase in a 1:1 scale and evaluate the chosen sequence.

Keywords: CAD | Disassembly | Sequence | TMU | Virtual Reality

Abstract: The present paper is about a family car project that starts from a study of the characteristics of the type of car taken into consideration and from an analysis of the environment carried out through an historical research on the models on the market from the 30s to the mid-90s, and their classification. The market analysis was carried out by answering six questions from the QFD and by developing the tables of relative importance and interrelation through which the most important and the most independent requirements to be attributed to the innovative family project were obtained. The competitor analysis was made through a research on the models currently on the market, the development of the benchmarking, and the what/how matrix from which the final requirements and project objectives were determined. The brand was selected, the budget was drawn up over a 12-month period and the car’s product architecture was defined. The SDE was carried out through an aesthetic analysis of the existing models, the sketches for each type of style and the selection of the final sketches. The development of the product, instead, consisted in the prototyping of a 1:18 scale model of the car through 3D printing.

Keywords: 3D Printing | CAD | QFD | Rendering | SDE

Abstract: Nowadays, the importance of the concept of “Urban Mining” is growing even more, which consists in searching for raw materials inside objects that have reached the end of their life, instead of “inside nature”. It can be commonly found especially in mechanical and electronic equipment valuable materials, which can be extracted and reused as secondary raw materials. The importance of Design for Disassembly (DfD), that is the central topic of this paper, is increasing because of it brings great advantages in terms of disassembly times of components that have reached the end of life. According to the Disassembly Sequence Planning (DSP), this paper presents an application of several methods derived from literature to a two-way valve, to find optimal disassembly sequences. Different sequences have been compared in terms of disassembly time consuming, by the conversion of operations into disassembly time using accredited methods found in literature. Finally, an application in Augmented Reality is proposed to simulate a practical evaluation of what has been theorised so far.

Keywords: Augmented Reality | CAD modelling | Design for Disassembly | Sequence Planning

Abstract: This work aims to present the application of mechanical modeling software in three dimensions in the medical field, analyzing the procedures used by the engineer to support the orthopedic surgeon in preoperative planning. The first step of the procedure involves CT examinations in patients selected for surgery: DICOM images are managed in post-processing to obtain multiplanar reconstructions of the bone lesion to be treated. The files are then optimized, made shareable and imported into CREO's work platform; this is part of a family of CAD software products for mechanical design, developed by PTC, and is the fundamental application dedicated to parametric modeling. The result will be a faithful representation of the anatomical part both before and after surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, than he will communicate them to the engineer who, consequently, will correct and regenerate the model. The method finds its power in the dialogue between engineer and doctor: In complex cases closer collaboration is needed while, for the evaluation of less demanding injuries, the exam could be assigned as a remote project which, once completed, is returned to the medical facility of competence.

Keywords: 3D modeling | Computer aided | Parametric software | Preoperative planning | Surgical simulation

Abstract: The life of industrial products is getting shorter due to the rapid evolution of technologies. Because of that, the creation of models that are interested in last part of the product’s life are becoming extremely relevant. In recent years, many investments have been made in the recycling of raw materials and the reuse of End-Of-Life (EOL) products in order to reduce the waste of resources. Strategies of Design for Environment (DfE) have been searched and, for this reason, the Design for Disassembly (DfD) has become a fundamental phase in the product life cycle with the subsequent creation of design techniques aimed precisely at disassembly. Using this methodology, the designer can study and plan the optimal sequence which should be based on countless factors and criteria because there is not a straightforward path or a single combination of operations to follow. This paper describes and compares multiple disassembly methods based on minimum disassembly time with reference to a worm gear reducer. In particular, the component was made entirely on CAD (SolidWorks) and the sequences were pplied in a virtual environment. In this way, it was possible to evaluate different algorithms and obtain the optimal disassembly sequence that minimize the overall disassembly time.

Keywords: CAD | Disassembly | Sequence | TMU | Virtual Reality

Abstract: Engineering design shows a growing interest in exploring cost analysis to anticipate manufacturing issues and integrate production aspects within the product development process. This research aims to highlight key elements (inputs, parameters, models) to accurately predict the cost of a forged part using a complete model, with important information that can be available during the design phase. For this purpose, a systematic literature review of existing engineering methodologies developed for cost analysis of forged parts (i.e., cost estimation, DtC, and ABC) was performed with characterizations of the different approaches for evaluating the most important topics related to this objective. As a result, the most important insights related to the aim of this review are provided: (i) among quantitative methods, analytical and parametric models are the most suitable approaches to develop a cost estimation, (ii) a cost model based on a linear equation supported by single or multiple variables seems to be the most accurate tool to establish a robust cost analysis in the design of forged components, and (iii) input parameters related to the material type and geometrical features are the most critical cost-drivers in the cost assessment. Moreover, this review contributes to identifying emerging applications and obsolete topics, providing the ground to investigate unexplored areas relevant to future research.

Keywords: CAD | CAE | Cost assessment | Cost model | Engineering knowledge | Forging | Material processing | Systematic literature review

Abstract: Welding is a consolidated technology used to manufacture/assemble large products and structures. Currently, welding design issues are tackled downstream of the 3D modeling, lacking concurrent development of design and manufacturing engineering activities. This study aims to define a method to formalize welding knowledge that can be reused as a base for the development of an engineering design platform, applying design for assembly method to assure product manufacturability and welding operations (design for welding (DFW)). The method of ontology (rule-based system) is used to translate tacit knowledge into explicit knowledge, while geometrical feature recognition with parametric modeling is adopted to couple geometrical information with the identification of welding issues. Results show how, within the design phase, manufacturing issues related to the welding operations can be identified and fixed. Two metal structures (a jack adapter of a heavy-duty prop and a lateral frame of a bracket structure) fabricated with arc welding processes were used as case studies and the following benefits were highlighted: (i) anticipation of welding issues related to the product geometry and (ii) reduction of effort and time required for the design review. In conclusion, this research moves forward toward the direction of concurrent engineering, closing the gap between design and manufacturing.

Keywords: CAD | Design for manufacturing and assembly | DFMA | Engineering design | Feature recognition | Knowledge-based system | Rule-based system | Welded structure | Welding

Abstract: The paper proposes a method to couple manufacturing knowledge in the context of casting with 3D CAD modelling and design. The approach allows formalizing tacit into explicit design knowledge, for aiding engineers during the development of metal casted components. It is based on three main pillars: (i) identification of geometrical features (3D CAD features) and parameters that can cause an issue during the manufacturing process, (ii) definition of a numerical threshold for feature parameters that guarantee the feasibility of the casting process, and (iii) representation of design rules within a CAD system to support product design review. The method is considered the starting point for future developing a software tool (CAD tool plug-in), here just presented. Two case studies are reported with the aim to show the advantages of the proposed method and tool in the identification of manufacturing issues early in the product development process. Results highlight how the CAD-based tool is a useful assistant to avoid design problems related to the metal casting process.

Keywords: CAD | Design for casting | Design rules | DFMA | Embodiment design | Mechanical products

Abstract: The work carried out has the purpose of improving and optimizing various industrial technical operations, such as preventive maintenance, taken here as an example of application, using the Design for Disassembly (DfD) technique. Therefore, through four metaheuristic methods that have been chosen among the most widespread in the field (described below) to make a comparison between them, the optimal disassembly sequence is sought, if it exists, in terms of time and then costs in order to extract a target component without damaging the other mechanical parts of the assembly. The hypothesis that has been tested throughout this case study is “a responsible application of DfD, not only from the design process of a product but also during the disassembly procedure, can bring substantial benefits to the company”. Interaction with a hypothetical operator in charge of the work to be performed is implemented with the use of augmented reality. In fact, through an application programmed for an Android device (in this case, a mobile phone, hence a handheld device), the operator can be instructed step-by-step on the disassembly sequence in dynamics as an animation. Finally, two virtual buttons were added in augmented reality with which the operator can start and pause/resume the animation at any time to facilitate the understanding of the different steps established by the sequence.

Keywords: Augmented reality | CAD | DFD | Industrial maintenance | Optimization

Abstract: This work shows a preoperative simulation procedure with Computer Aided Design (CAD) 3D software for a patient suffering from Ollier's disease. This pathology is very rare and occurs in extremely different ways depending on the case. Consequently, it is difficult to establish a correct surgical strategy that can be applied in a similar way to all patients. Computer Aided Surgical Simulation (CASS) process uses advanced modeling technologies to reproduce bony anatomy and simulate the surgery. The starting point is represented by the 3D digital model of the bone obtained from tomographic images. Through CAD modeling software such as Creo Parametric and following surgeons directives, engineers can provide doctors with orthopedic simulation and expectation of achievable surgical outcome. If virtual surgical prediction doesn’t meet doctors requirements, model is regenerated and it is possible to seek for a better solution. CASS process allow for extensive surgical planning, enhancing accuracy in theatre and enriching the amount of medical information that is needed to perform complex orthopedic procedures. In conclusion, the possibility to recognize in advance the overall orthopedic situation and outcoming expectancy represent an extraordinary upgrade of current surgical state of the art, leading to minimally invasive surgeries and patient-specific solutions.

Keywords: 3D modeling | CAD | CASS | Parametric software | Preoperative planning

Abstract: This paper introduces an e-learning platform for the management of courses based on MOOCs, able to continuously monitoring student’s behavior through facial coding techniques, with a low computational effort client-side, and to provide useful insight for the instructor. The system exploits the most recent developments in Deep Learning and Computer Vision for Affective Computing, in compliance with the European GDPR. Taking as input the video capture by the webcam of the device used to attend the course, it: (1) performs continuous student’s authentication based on face recognition, (2) monitors the student’s level of attention through head orientation tracking and gaze detection analysis, (3) estimates student’s emotion during the course attendance. The paper describes the overall system design and reports the results of a preliminary survey, which involved a total of 14 subjects, aimed at investigating user acceptance, in terms of intention to continue using such a system.

Keywords: Affective Computing | Deep Learning | E-leaning | Facial Coding | Facial Recognition

Abstract: Obstructive sleep apnoea syndrome is characterized by an obstruction in the upper airway due to the pharyngeal collapse during sleep. Mandibular advancement devices have gained success and large popularity as a non-invasive treatment for OSAS. Nevertheless, the effects of mandibular advancement devices were poorly investigated in literature. To this aim the paper proposes a procedure to achieve a numerical simulation model useful to assess the stress/strain distribution on the temporomandibular joint and periodontal ligaments caused by the mandibular advancement. The findings suggest that the mandibular roto-translation induced by the MAD provoke high stress on the molars and premolar teeth.

Keywords: Computer aided design | Finite element method | Mandibular advancement device | Periodontal ligaments | Temporomandibular joint

Abstract: Obstructive sleep apnea syndrome (OSAS) is a sleep disorder that causes pauses in breathing or periods of shallow breathing during sleep. Mandibular advancement devices (MADs) represent a non-invasive treatment for OSAS that has had the highest development in recent years. Nevertheless, literature has not primarily investigated the effects of mandibular advancement. This paper presents a finite element method numerical simulation model for evaluating the stress/strain distribution on the temporomandibular joint (TMJ) and periodontal ligaments caused by advancement devices used for the treatment of OSAS. Results highlight that the mandible lift phase generates significant stress values on TMJ, which cannot be neglected for extended usage of MADs. Furthermore, mandible molar teeth are more loaded than incisor ones.

Keywords: Computer-Aided Design | Finite element method | Mandibular advancement device | Obstructive Sleep Apnea Syndrome | Virtual prototyping

Abstract: This article reports on the results of research aimed to translate biometric 3D face recognition concepts and algorithms into the field of protein biophysics in order to precisely and rapidly classify morphological features of protein surfaces. Both human faces and protein surfaces are free-forms and some descriptors used in differential geometry can be used to describe them applying the principles of feature extraction developed for computer vision and pattern recognition. The first part of this study focused on building the protein dataset using a simulation tool and performing feature extraction using novel geometrical descriptors. The second part tested the method on two examples, first involved a classification of tubulin isotypes and the second compared tubulin with the FtsZ protein, which is its bacterial analog. An additional test involved several unrelated proteins. Different classification methodologies have been used: a classic approach with a support vector machine (SVM) classifier and an unsupervised learning with a k-means approach. The best result was obtained with SVM and the radial basis function kernel. The results are significant and competitive with the state-of-the-art protein classification methods. This leads to a new methodological direction in protein structure analysis.

Keywords: 3D face analysis | differential geometry | geometrical descriptors | machine learning | protein classification | support vector machine | tubulin

Abstract: This work aims to identify people psychological stress through the capture of micro modifications and motions within their facial expression. Exogenous and endogenous causes of stress, from environment and/or psychological conditions that could induce stress, have been reproduced in the experimental test involving real subjects, and their face expressions have been recorded by 2D and 3D image capturing tools to create a sample of emotional database. Successively, 2D and 3D analyses have been performed on recorded data according to the respective protocols, by deep learning and machine learning techniques, and a data driven model of the databases has been developed by neural network approach, to classify the psycho-behavioral answers to the different kinds of stress conditions induced on tested people. The ultimate aim of the study is to demonstrate the possibility to analyze data collected on participants from 2D shooting and 3D scans in a consistent way by means of deep learning and machine learning techniques, so that to provide a methodology to identify and classify some of the subtle facial micro-expressions of people involved in stressing activities.

Keywords: Deep learning | Emotion detection | Image recognition | Machine learning | Neural networks

Abstract: Facial Emotion Recognition (FER) is the automatic processing of human emotions by means of facial expression analysis[1]. The most common approach exploits 3D Face Descriptors (3D-FD)[2], which derive from depth maps[3] by using mathematical operators. In recent years, Convolutional Neural Networks (CNNs) have been successfully employed in a wide range of tasks including large-scale image classification systems and to overcome the hurdles in facial expression classification. Based on previous studies, the purpose of the present work is to analyze and compare the abstraction level of 3D face descriptors with abstraction in deep CNNs. Experimental results suggest that 3D face descriptors have an abstraction level comparable with the features extracted in the fourth layer of CNN, the layer of the network having the highest correlations with emotions.

Keywords: Abstraction | CNN | Deep learning | Explainable AI | Facial Emotion Recognition | FER

Abstract: The eutectic alloy Lithium Lead (LiPb) enriched at 90 % in 6Li is the breeder material for one of the candidate European Breeding Blanket (BB) concepts. Currently under investigation for DEMO reactor, the Water Cooled Lithium-Lead (WCLL), and for the WCLL Test Blanket Module (TBM) that will be qualified in the ITER reactor. The LiPb alloy is used as tritium breeder, neutron multiplier and tritium carrier. The design of the LiPb loops is currently under study and the conceptual design of the main loop components has been completed. For this reason, it becomes mandatory to proceed with the integration of the LiPb loops in the EU DEMO Tokamak building, checking the consistency of the different systems design to be integrated in DEMO reactor building. CAD design and integration of the entire LiPb loops are shown taking into account the building areas assigned, the interfaces with the other systems and the requirement related to the LiPb loop functions. An initial layout of the pipework and the position of the main components have been defined on the basis of the following design requirements: (I) gamma radiation shielding of the components and the pipework; (II) target flow velocity of the LiPb; (III) thermal expansion of the pipes; (IV) possibility to drain the entire loop; (V) redundancy of the loops; (VI) remote maintenance; (VII) position in the building and dimensions of the storage tanks. The 3D model of the entire loops has been provided and integrated in DEMO Tokamak building pointing out the issues related to the interfaces with the other systems and with the building itself.

Keywords: Breeding blanket | CAD | DEMO | Integration | Lithium lead | Piping design | Water cooled lithium lead

Abstract: The Industry 4.0 framework is pushing the manufacturing systems towards a zero-defect production based on robot technologies. The increasing level of automation in the production lines is raising new challenges for designers that must face the latest requirements in terms of product quality and power consumption. Among the multitude of components of the industrial plants, Servo-Mechanisms (SMs) play a crucial role and govern important performance indices of both robots and automatic machines. During the execution of high dynamics tasks, the SMs performance is influenced by many factors, including motion law, acting load, temperature and degradation. The development of accurate models aiming at predicting and optimizing the SMs behavior may not be practicable without extensive experimental activities. Owing to these considerations, this work introduces a novel test rig for the accurate characterization of industrial SMs. The rig is designed by combining the advantages of the existing prototypes. It is equipped with high precision sensors and an active loading system that enable to test the SM in various working conditions. Also, the rig modularity facilitates the installation of newly commissioned components and the execution of static and dynamic experiments. The paper mainly focuses on the rig mechanical design and components selection criteria.

Keywords: Computer Aided Design | Design methods | High Precision Manufacturing | Industry 4.0 | Servo-Mechanism Test Rig

Abstract: Purpose: The current study aimed to propose a Deep Learning (DL) and Augmented Reality (AR) based solution for a in-vivo robot-assisted radical prostatectomy (RARP), to improve the precision of a published work from our group. We implemented a two-steps automatic system to align a 3D virtual ad-hoc model of a patient’s organ with its 2D endoscopic image, to assist surgeons during the procedure. Methods: This approach was carried out using a Convolutional Neural Network (CNN) based structure for semantic segmentation and a subsequent elaboration of the obtained output, which produced the needed parameters for attaching the 3D model. We used a dataset obtained from 5 endoscopic videos (A, B, C, D, E), selected and tagged by our team’s specialists. We then evaluated the most performing couple of segmentation architecture and neural network and tested the overlay performances. Results: U-Net stood out as the most effecting architectures for segmentation. ResNet and MobileNet obtained similar Intersection over Unit (IoU) results but MobileNet was able to elaborate almost twice operations per seconds. This segmentation technique outperformed the results from the former work, obtaining an average IoU for the catheter of 0.894 (σ = 0.076) compared to 0.339 (σ = 0.195). This modifications lead to an improvement also in the 3D overlay performances, in particular in the Euclidean Distance between the predicted and actual model’s anchor point, from 12.569 (σ= 4.456) to 4.160 (σ = 1.448) and in the Geodesic Distance between the predicted and actual model’s rotations, from 0.266 (σ = 0.131) to 0.169 (σ = 0.073). Conclusion: This work is a further step through the adoption of DL and AR in the surgery domain. In future works, we will overcome the limits of this approach and finally improve every step of the surgical procedure.

Keywords: Deep learning | Intra-operative | Neural network | Semantic segmentation

Abstract: The aim of the current work was to analyze the influence of the ferrule effect for hybrid composite endodontic post designs consisting of carbon (C) and glass (G) fiber-reinforced polyetherimide (PEI), in upper canine teeth. Starting from theoretical designs of C-G/PEI hybrid composite posts with different Young's moduli (Post A-57.7 GPa, Post B-31.6 GPa, Post C-graduated from 57.7 to 9.0 GPa in the coronal-apical direction) in endodontically treated anterior teeth, the influence of the ferrule effect was determined through finite element analysis (FEA). On the surface of the crown, a load of 50 N was applied at 45° to the longitudinal axis of the tooth. Maximum principal stresses were evaluated along the C-G/PEI post as well as at the interface between the surrounding tooth structure and the post. Maximum stress values were lower than those obtained for the corresponding models without a ferrule. The presence of a ferrule led to a marked decrease of stress and gradients especially for posts A and B. A less marked effect was globally found for Post C, except in a cervical margin section along a specific direction, where a significant decrease of the stress was probably due to local geometric features, compared to the model without a ferrule. The presence of a ferrule did not generally provide a marked benefit in the case of the graduated Post C, in comparison to other C-G/PEI posts. The outcomes suggest how such a hybrid composite post alone should be sufficient to optimize the stress distribution, dissipating stress from the coronal to the apical end.

Keywords: Computer-Aided Design | Endodontic post design | Finite element analysis | Polyetherimide composites | Reverse engineering

Abstract: Industry 4.0 promises to increase the efficiency of production plants and the quality of the final product. Consequently, companies that implement advanced solutions in production systems will have a competitive advantage in the future. The principles of Industry 4.0 can also be applied to shipyards to transform them into “smart shipyards” (Shipyard 4.0). The aim of this research is to implement an interactive approach by Internet of Things on a closed power-loop test bench equipped with sophisticated sensors that is specifically designed to test high-power thrusters before they are installed on high-speed crafts, which are used in passenger transport. The preliminary results of the proposed Internet of Things-platform demonstrates the efficacy of the decision-making support tool in improving the design of propulsion systems and increasing their efficiency compared to traditional systems.

Keywords: CAD modelling | Experimental tests | Industry 4.0 | Internet of Things (IoT) | Test bench

Abstract: Total elbow arthroplasty (TEA) is an effective and frequently used treatment for patients with debilitating elbow pathology. Total elbow prostheses have lagged behind those of the knee, hip and shoulder for different reasons, such as the high failure rate of the early designs. Concern remains regarding the longevity of TEA implants, especially in younger patients. The main cause of revision of the implant is usually related to the phenomenon of aseptic loosening mainly due to the cement-bone interface failure. Aim of this work is the biomechanical analysis of a new elbow prosthesis to investigate the mechanical behaviour at the cement-bone interface. For this reason, a musculoskeletal model has been developed by modelling the forces of the muscles and after FEM analyses have been performed. Obtained results confirm the validity of the implemented model and can provide guidelines for surgeons regarding the implant configurations with the aim to reduce the aseptic loosening.

Keywords: CAD | FEM | Reverse engineering | Total elbow arthroplasty

Abstract: Potteries are the most numerous finds found in archaeological excavations; they are often used to get information about the history, economy, and art of a site. Archaeologists rarely find complete vases but, generally, damaged and in fragments, often mixed with other pottery groups. By using the traditional manual method, the analysis and reconstruction of sherds are performed by a skilled operator. Reviewed papers provided evidence that the traditional method is not reproducible, not repeatable, time-consuming and its results have great uncertainties. To overcome the aforementioned limits, in the last years, researchers have made efforts to develop computer-based methods for archaeological ceramic sherds analysis, aimed at their reconstruction. To contribute to this field of study, in this paper, a comprehensive analysis of the most important available publications until the end of 2019 is presented. This study, focused on pottery fragments only, is performed by collecting papers in English by the Scopus database using the following keywords: "computer methods in archaeology", "3D archaeology", "3D reconstruction", "automatic feature recognition and reconstruction", "restoration of pottery shape relics". The list is completed by additional references found through the reading of selected papers. The 53 selected papers are divided into three periods of time. According to a detailed review of the performed studies, the key elements of each analyzed method are listed based on data acquisition tools, features extracted, classification processes, and matching techniques. Finally, to overcome the actual gaps some recommendations for future researches are proposed.

Keywords: 3D archaeology | 3D reconstruction | Automatic feature recognition and reconstruction | Computer methods in archaeology | Restoration of pottery shape relics

Abstract: Secondary features, such as fillets, rounds, chamfers and grooves, are simple transitions between primary features, generally introduced in order to remove the sharp edges created by the intersection of primary features. Being able to distinguish secondary from primary features is important in various application contexts, such as reverse engineering, automatic geometric inspection of real scanned objects, and for preparation of models for FEM analysis and CNC tool-path generation. The process for the recognition of secondary features from high-density tessellated models of real work-pieces is intrinsically complex for several reasons. This explains why, currently, there are no methodologies able to recognize automatically secondary features and the investigation on secondary features is mostly focused on B-Rep models. In a previous paper, the authors proposed a method for secondary features recognition from discrete geometric models synthetically generated. Here the methodology is extended to discrete geometric models experimentally acquired, for which the recognition is a very complex process, due to the object discretization, to its non-ideal geometry and to measurement errors.

Keywords: Blending features | Feature recognition | Fuzzy logic | Point cloud segmentation

Abstract: Sports equipment design is a young and evolving engineering discipline focused on the best simultaneous optimization of user and product as a system. In motorsports, in particular, the final performance during a race depends on many parameters related to the vehicle, circuit, weather, and tyres and the personal feelings of every single driver. Top teams in high-tech categories can invest huge amounts of money in developing simulators, but such economic commitment is not sustainable for all those teams that operate in minor but very popular categories, such as karts or mini-motorcycles. In these fields, the most common design approach is trial and error on physical prototypes. Such an approach leads to high costs, long optimization times, poor innovation, and inefficient management of the design knowledge. The present paper proposes a driver centred methodology for the design of an innovative mini racing motorcycle frame. It consists of two main phases: the drivers’ feelings translation into engineering requirements and constraints, and the exploration of the design solution space. Expected effects of the application of the proposed methodology are an overall increase in the degree of innovation, time compression, and cost reduction during the development process, with a significant impact on the competitiveness of small racing teams in minor categories.

Keywords: Design methodology | Racing motorcycle frame design | Topological optimization

Abstract: The aim of this work is the design of a new customised elbow orthosis completely realized by Additive Manufacturing and the development of generative algorithms for parametric modelling and creation of 3D patterns to be adapted to the CAD model. This work describes a method to perfect the design of a custom elbow orthosis. A reverse engineering approach has been used to digitalize the patient’s arm and the subsequent CAD modelling of the structure of the custom elbow orthosis has been performed. In particular, two algorithms have been implemented for the creation of 3D patterns and Voronoi tessellations. Subsequently, FEM analyses have been carried out to validate the design. Finally, a prototype of the elbow orthosis with Voronoi tessellation has been realized by means of the SLS technology. The results obtained have demonstrated that the implemented algorithm solved the problems found during CAD modelling with conventional software. Furthermore, the results of FEM analyses have validated the design choices. All this allowed realizing the prototype by AM technologies without problems. Moreover, the new proposed modelling approaches allows creating, in an interactive way, patterns on complex surfaces. The results of this research activity present innovative elements of originality in the CAD modelling sector, which can contribute to solving problems related to the modelling for Additive Manufacturing. Furthermore, another innovative characteristic of the device is the use of torsion springs that simulate the action of physiotherapists during exercises for patient rehabilitation.

Keywords: Additive manufacturing | Computer aided design | Elbow orthosis | Generative design | Reverse engineering

Abstract: Tibial fractures are common injuries in people. The proper treatment of these fractures is important in order to recover complete mobility. The aim of this work was to investigate if screw positioning in plates for proximal tibial fractures can affect the stability of the system, and if it can consequently influence the patient healing time. In fact, a more stable construct could allow the reduction of the non-weight-bearing period and consequently speed up the healing process. For that purpose, virtual models of fractured bone/plate assemblies were created, and numerical simulations were performed to evaluate the reaction forces and the maximum value of the contact pressure at the screw/bone interface. A Schatzker type I tibial fracture was considered, and four different screw configurations were investigated. The obtained results demonstrated that, for this specific case study, screw orientation affected the pressure distribution at the screw/bone interface. The proposed approach could be used effectively to investigate different fracture types in order to give orthopaedists useful guidelines for the treatment of proximal tibial fractures.

Keywords: CAD | FEM | Implant stability | Locking plates | Reverse engineering | Tibial fracture

Abstract: Purpose: The purpose of this paper is to implement a new process aimed at the design and production of orthopaedic devices fully manufacturable by additive manufacturing (AM). In this context, the use of generative algorithms for parametric modelling of additively manufactured textiles (AMTs) also has been investigated, and new modelling solutions have been proposed. Design/methodology/approach: A new method for the design of customised elbow orthoses has been implemented. In particular, to better customise the elbow orthosis, a generative algorithm for parametric modelling and creation of a flexible structure, typical of an AMT, has been developed. Findings: To test the developed modelling algorithm, a case study based on the design and production of an elbow orthosis made by selective laser sintering was investigated. The obtained results have demonstrated that the implemented algorithm overcomes many drawbacks typical of the traditional computer aided design (CAD) modelling approaches. The parametric CAD model of the orthosis obtained through the new approach is characterised by a flexible structure with no deformations or mismatches and has been effectively used to produce the prototype through AM technologies. Originality/value: The obtained results present innovative elements of originality in the CAD modelling sector, which can contribute to solving problems related to modelling for AM in different application fields.

Keywords: Additive manufacturing | Additively manufactured textiles | AM technologies | CAD modeling | Elbow orthosis | Generative algorithms

Abstract: Tooth loss is a common pathology that affects many people. Dental osseointegrated implants are the ideal solution to restore normal functionality in partially or completely edentulous patients. The not perfect osseointegration and the fixture fracture are the main causes of failure for these kinds of implant. To avoid these drawbacks, several studies have been conducted to analyse the behaviour of dental implants. Aim of this work is to analyse the biomechanical behaviour of three different endosseous dental implants. For this purpose, a new numerical model has been developed to simulate different levels of osseointegration and to evaluate the stress values on the bone at different times. In this way, it can be investigated the possibility of anticipating the use of dental implants that usually is delayed three months after surgery. Obtained results confirm the validity of the proposed approach and can provide useful guidelines for dentists.

Keywords: CAD | Dental implant | FEM | Osseointegration | Virtual simulation

Abstract: In the last two decades, osseointegrated prostheses have been shown to be a good alternative for lower limb amputees experiencing complications in using a traditional socket-type prosthesis; however, restraining biomechanical issues, such as peri-prosthetic bone fractures or loosening, are present. To better understand and overcome these limiting issues, and thus reduce the number of implant failures, many studies have investigated the stress distribution on bone and implant during normal daily activities. The aim of this study was a biomechanical analysis of two different osseointegrated implants, a screw-type (OPRA) and a press fit system (OPL, Osseointegrated Prosthetic Limb), to evaluate the stresses generated in bone and prosthesis during a fall. In particular, four scenarios have been experimentally reproduced to determine the loads on the limb during different kinds of fall. For this purpose, a motion capture system and a force plate have been used. Numerical FEM (Finite Element Method) simulations have been performed to compare the behaviour of the OPRA and OPL systems in different fall scenarios. The obtained results showed that a fall backwards due to balance loss is the most stressful scenario among the ones analysed. As regards the comparison between OPRA and OPL devices, it emerged they have similar behaviours in terms of peak values of the stress, but the OPL implant generates larger high-stress areas in the distal femur as compared with the OPRA system.

Keywords: CAD | Finite element analysis | OPL osseointegrated prosthesis | OPRA | Transfemoral amputee

Abstract: The current generation of transcatheter heart valves (THV), as the Edwards SAPIEN 3 Ultra (S3), is not specifically designed for mitral position implantation and has intrinsic design geometry that may make mitral implantation suboptimal. This study aimed to develop a computed-tomography (CT) based CAD workflow for the preoperative planning of transcatheter mitral valve replacement (TMVR) by evaluating the resulting obstruction in the left ventricular outflow tract (LVOT). Specifically, the computational framework to reconstruct heart anatomy and virtually deploy the THV into mitral valve annulus was developed and successively applied to the cases of two patients who experienced annuloplasty ring failure. Planimetric assessment of the cross-sectional area of the neo-LVOT was quantified at different anatomic levels of implanted THV. Findings revealed the importance of the proposed CAD modeling workflow to enable more informative pre-operative assessments of the risk related to the development of the neo-LVOT obstruction and even to guide the Heart Team regarding device selection, sizing and intended positioning for TMVR.

Keywords: CAD | Medical imaging | Reverse engineering | Transcatheter mitral valve replacement | Virtual simulation

Abstract: Parallel-sided foil sections are used for centerboards and rudders in sailing dinghy classes and also for struts placed in a fluid flow. The objective of this work is to create a systematic series of parallel-sided sections to be used under different conditions, with an emphasis on the sailing dinghies 470, 420 and Optimist. The loss, and surprisingly the gain, in performance relative to 4-digit NACA sections are also investigated. A 2D Reynolds-averaged Navier-Stokes solver is used with the k-ω SST turbulence model and the gamma transition criterion. A verification study is carried out based on four grids of systematically varied density, and results compared with experimental data on a NACA 64-006 section. The parallel-sided sections are modeled with rational Bézier curves whose geometrical parameters permit to link the shape of the profile to physical variables, which are systematically varied. Three Reynolds numbers and two angles of attack are investigated. Systematic plots show the influence of the trailing edge angle and nose radius for the different section families, and the optimum combination is presented in a table. Physical explanations of the trends, and of the exceptions, are given in the paper, using flow visualizations as well as pressure and friction plots.

Keywords: Bézier curves | CAD | Centerboard | Gamma transition criterion | Low Reynolds number | NACA | Parallel-sided | Sailing | Systematic investigation

Abstract: One of the main challenges in the roadmap to the realization of fusion energy is to develop a heat and power exhaust system able to withstand the large loads expected in the divertor of a fusion power plant. The challenge of reducing the heat load on the divertor targets is addressed, within the mission 2 ‘Heat-exhaust systems’, through the investigation of divertor configurations alternative to the standard Single Null (SN), such as the Snowflake (SF), Double Null (DN), X and Super-X (SX) divertors. This paper focuses on a preliminary engineering assessment of the alternative configurations proposed for the EU DEMO reactor. Starting from the description of the optimized plasma shape developed for each configuration, the 3D geometrical description of the Magnet System and of the main Mechanical Structures (Vacuum Vessel and in-vessel components) is presented. Based on the 3D geometry, the compatibility of the location and dimensions of ports with Remote Maintenance needs is discussed and possible design optimizations are proposed both for the Magnets system and the mechanical structures design. Finally, the various configurations are compared with regard to the engineering and feasibility aspects.

Keywords: Alternative magnetic configurations | CAD | Conceptual design | DEMO | Divertor concept

Abstract: This paper reports about the virtual and physical prototyping of an antagonistic Variable Stiffness Actuator (VSA) to be used on robotic arms specifically realized for physical human-robot interaction. Such antagonistic actuation system, which comprises purposely conceived Compliant Transmission Elements (CTEs) characterized by a nonlinear relation between the deflection and the applied torque, allows to simultaneously control both the joint's position and stiffness. The CTE's beams geometry, namely slender spline beams, has been defined by means of an automatic routine leveraging on Matlab and ANSYS and allowing for the shape optimization of complex flexures. The synthesized springs are characterized by a predefined quadratic torque-deflection characteristic, which is shown to guarantee a precise stiffness modulation while avoiding the need for a joint's position sensor. After shape optimization, the CTE is fabricated via additive manufacturing and subsequently tested. The acquired data show a very good consistency with the numerical results, although highlighting a non-negligible hysteresis due to material damping. Therefore, in order to cope with such unavoidable effect along with other parameter uncertainties and unmodeled effects (e.g. static friction), a robust feedback controller is proposed, allowing for the simultaneous and decoupled regulation of joint position and stiffness. Finally, a VSA prototype is produced and tested. Experimental results confirm that the VSA behaves as expected.

Keywords: Compliant mechanisms | Multi software framework | Shape optimization | Sliding mode controller | Variable stiffness actuators

Abstract: The paper describes a novel Clench-and-Release Device (CRD), which can be used to quickly replace the rear wheels of bikes equipped with disk brakes, while also being suitable for front wheels. Since a quick wheel replacement is a pressing demand during competitions, the CRD reduces time wasted in situations like flat tire replacement. At the same time, it can be useful also for amateur bikers, who desire a simple way to lock/release a wheel without the risk of getting dirty or being unable to properly align the brake’s disk and pads. In fact, thanks to the CRD, both brake and pinion packs are kept in place at all times and the chain remains engaged with the gears, even after wheel removal. Although similar devices can be found on the market, the proposed CRD provides an improved design since: (i) pinions and brake are placed on the same side with respect to the wheel symmetry plane perpendicular to the wheel axis of rotation; (ii) the front and the rear wheel share the same hub; (iii) manual operations are definitely easier; (iv) the wheels are compatible with different types of transmission; (v) the brake discs are more protected in case of crashing. A patent for the Italian region has been filed.

Keywords: Computer-aided design | Through axle shaft | User centered design | Wheel quick release | Wheels’ fast removal

Abstract: This paper reports the design of a monolithic long-stroke constant force compliant mechanism (CM). The device is suitable for applications requiring a predefined force magnitude at the contact interface, such as manipulation systems. Starting from a compliant slider-crank mechanism providing a constant force within a rather limited deflection range, the paper describes the shape optimization carried out with the aim of extending the CM available stroke. In the first design step, the pseudo-rigid body (PRB) method is used to synthesize a sub-optimal lumped compliance solution. Secondly, two improved beam-based alternatives are evaluated by means of an integrated software framework, comprising Matlab and ANSYS. These new embodiments make use of a variable thickness beam, whose shape and dimensions have been optimized so as to provide a constant reaction force in an extended range. In particular, straight and spline segments are respectively used for the first and second prototype. With reference to the lumped compliance configuration, the available stroke has been increased of amounts equalling to 467% in the straight segments version (namely, from 3 mm to 14 mm) and to 833% in the spline segments version (namely, from 3 mm to 25 mm). All the predicted behaviors have been validated via physical experiments on 3D printed specimens. The proposed multi-step design flow may also be applied to a large variety of CMs, starting from their PRB model.

Keywords: compliant mechanisms | constant force mechanisms | pseudo-rigid body method | shape optimization | software integration

Abstract: Planning prototyping strategies for conceptual design purposes is a crucial activity, which needs a clear understanding of the potentialities of the different typologies of prototype. Therefore, to prepare future designers, it is very important to provide the required information in design-related academic courses. However, prototypes and prototyping activities are often taught in specific courses with a major emphasis on the underpinning technologies, but with limited attention on design implications, especially about the fuzzy-front-end of the design process. The work presented in this paper aims at investigating about how students perceive the usefulness of prototypes during conceptual design activities, in order to provide first indications about the gap to be filled. To this purpose, two classes of students participated to an experimental session, and were asked to perform a conceptual design task individually. Subsequently, they participated to an on-line survey developed to gather information about the perceived usefulness of prototypes, in relation to the performed conceptual design activity. Several findings have been obtained from this work, but maybe the most impacting one concerns the different consideration that the two samples of students had about the fidelity of prototypes. Indeed, differently from what recently highlighted in current literature, it emerged that engineering students preferred low-fidelity prototypes. However, other unexpected evidences have been found, which highlight that at least for the considered institution, students still lack a comprehensive understanding of the design-related potentialities of prototypes.

Keywords: Additive manufacturing | CAD | Design | Design education | Engineering education | Prototyping

Abstract: Background and objective:Tomographic sequences of biomedical images are commonly used to achieve a three-dimensional visualization of the human anatomy. In some cases, the number of images contained in the sequence is limited, e.g., in low-dose computed tomography acquired on neonatal patients, resulting in a coarse and inaccurate 3D reconstruction. Methods:In this paper, volumetric image interpolation methods, devised to increase the axial resolution of tomographic sequences and achieve a refined 3D reconstruction, are proposed and compared. The techniques taken into consideration are based on motion-compensated frame-interpolation concepts, which have been developed for video applications, mainly frame-rate conversion. Results: The performance of the proposed methods is quantitatively assessed by using sequences with a simulated low axial resolution obtained from the decimation of standard high-resolution computed tomography sequences. Real data with an actual low axial resolution have been used as well for a qualitative evaluation of the proposed methods. Conclusions:The experimental results demonstrate that the proposed methods enable an effective slice interpolation and that the achievable 3D models clearly benefit from the increased axial resolution.

Keywords: 3D reconstruction | Biomedical image sequences | Computer tomography | Optical flow | Registration | Volumetric interpolation

Abstract: Generative design tools have recently become an interesting solution to tackle design problems in several technical fields. This article takes into consideration the specific field of mechanical design and aims at describing available generative design solutions capable of dealing with structural optimization problems. The study provides a practical description on the workflow and performances of a specific software system implementing a generative approach for the generation of a set of alternative solutions for a static structural design problem. The software analyzed is Autodesk’s Generative Design, hosted in Fusion 360. The article discusses the functioning of the software and its performances; an enhanced focus on the features oriented to the generation of manufacturable shapes is provided in the text. In order to provide a practical and effective procedure, a literature case study was selected to test the software.

Keywords: Biomimetic Design | CAD | Generative Design | Structural Optimization | Topology Optimization

Abstract: Computer Aided reconstruction of mechanical parts nowadays heavily relies on dedicated RE software systems and highly skilled users to be carried out effectively. This paper investigates this scenario in order to identify most limiting factors in the current framework. With this respect, several considerations of general validity are drawn while presenting the problem from a theoretical perspective. A significant test case reconstruction, discussed in depth in the manuscript, is used to provide a practical point of view on real applications and help the reader acquire a hands-on comprehension of the current situation.

Keywords: CAD | CAD reconstruction | Reverse engineering

Abstract: In patients affected by craniosynostosis, i.e. a congenital cranial defect, diagnostic evaluation for a prompt surgical treatment is performed using low-dose three-dimensional computer tomography (CT), characterized by a poor spatial resolution (in terms of slice thickness). The limited number of CT images reduces the accuracy of the 3D reconstruction of the skull and leads to a coarser segmentation and modelling. In this paper, Motion Compensated Frame Interpolation (MCFI) techniques are applied for an effective axial interpolation of tomographic images sequences, with the main objective of obtaining a refined 3D reconstruction. The performance of the proposed method was assessed by using high-resolution CT sequences. After downsampling along the axial direction, the missing slices were recovered by using the proposed algorithm, to obtain an estimate of the original sequence. The experimental results show that the 3D models obtained from the downsampled/interpolated sequence are very close to those obtained from the original one thus providing a high-quality 3D skull reconstruction.

Keywords: 3D modeling | CT slices | Interpolation | Motion compensation

Abstract: The present paper presents the study of a semi-automatic CAD technique for the generation of ventilation holes on ABS AM-manufactured arm orthoses. A lighter device, good air and water transpiration and an increased patient’s comfort are the main advantages achievable by introducing openings on plastic casts. The proposed procedure relies on the adaptation of a reference pattern of holes, obtained integrating both structural and functional aspects, to each patient’s cast. The adaptation procedure maps the original pattern, respecting its proportions, on each target orthosis, thanks to a set of reference points automatically extracted. The generation of holes is performed relying on an advanced CAD environment (i.e. Siemens NX), where a series of CAD modeling operations, based on the data extracted by the mapping algorithm, have been studied and tested. The whole procedure has been tested on 5 orthoses to validate its efficacy.

Keywords: Cad | Cast modeling | Orthosis modeling | Personalized medicine

Abstract: The interest in developing customized external orthopaedic devices, thanks to the advent of Additive Manufacturing (AM), has grown in recent years. Greater attention was focused on upper limb casts, while applications to other body’s parts, such as the neck, were less investigated. In this paper the computer aided design (CAD) modelling, assessment and 3D printing with fused deposition modelling (FDM) of a customized neck orthosis are reported. The modelling, based on anatomic data of a volunteer subject, was aimed to obtain a lightweight, ventilated, hygienic and comfortable orthosis compared to the produced medical devices generally used for neck injuries. CAD models with different geometrical patterns, introduced for lightening and improving breathability, were considered, specifically, a honeycomb pattern and an elliptical holes pattern. These models were structurally assessed by means of finite elements analysis (FEA). Furthermore, an innovative composite material was considered for 3D printing. The material, Hemp Bio-Plastic® (HBP), composed by polylactic acid (PLA) and hemp shives, offers different advantages including lightweight, improved superficial finish and antibacterial properties. The results obtained in terms of design methodology and manufacturing by 3D printing of a prototype have shown the feasibility to develop customized cervical orthoses, with potentially improved performance with respect to cervical collars available on the market also thanks to the use of the innovative composite material.

Keywords: Additive Manufacturing | Bio-composite | CAD | Neck orthosis

Abstract: In recent decades, increasing attention is being paid to the multidisciplinary approach that allows the performance of both a preventive conservation and a more invasive restoration action. In this context, the present study aims to acquire information and data from field surveys undertaken in San Domenico Church, Southern Calabria, in order to provide a tool for the recording and the inventory of damage and decay phenomena, and assess their causes and scale. The subsequent calculation of damage indices also provided useful information in order to allow the prioritization of conservation and preservation responses.

Keywords: Built heritage | Calabria | Computer graphics | Damage diagnosis | Decay | Italy | Photogrammetry

Abstract: The research on the use of virtual reality (VR) in the design domain has been conducted in a fragmentary way so far, and some misalignments have emerged among scholars. In particular, the actual support of VR in early design phases and the diffusion of practices involving VR in creative design stages are argued. In the present paper, we reviewed VR applications in design and categorized each of the collected 86 sources into multiple classes. These range from supported design functions to employed VR technologies and the use of systems complementing VR. The identified design functions include not only design activities traditionally supported by VR, such as 3D modelling, virtual prototyping, and product evaluation, but also co-design and design education beyond the early design phases. The possibility to support early design phases by means of VR is mirrored by the attention on products that involve an emotional dimension beyond functional aspects, which are particularly focused on in virtual assemblies and prototypes. Relevant matches between VR technologies and specific design functions have been individuated, although a clear separation between VR devices and supported design tasks cannot be claimed.

Keywords: 3D modelling | Co-design | Early design phases | Engineering design | Industrial design | Product design | Product evaluation | Technological development | Virtual prototyping | Virtual reality

Abstract: This paper presents a methodological procedure, based on the anatomical reconstruction and constrained deformation, to design custom-made implants for forehead augmentation in people affected by Apert syndrome, experiencing a frontal bone deficiency. According to the anthropometric theory, a cranial landmarks identification procedure was applied to retrieve, from a repository, a healthy skull, used as reference geometry for implant modelling. Then, using constrained deformation and free-form modelling techniques, it was possible to design a patient-specific implant. At last, the implant was realised using a custom mould, specially designed according to the patient’s needs to provide an accurate fit of the defect site. The design procedure was tested on a patient suffering from Apert syndrome. Three implants were virtually modelled and 3D-printed for pre-surgical evaluation. Their shapes were 3D compared with a reference one (handcrafted by a surgeon) to test the accuracy. Deviations are negligible, and the customised implant fulfilled the surgeon’s requirements.

Keywords: Computer-aided design | Craniomaxillofacial surgery | Implant design | Medical devices | Rapid prototyping

Abstract: In recent years, breakthroughs in the fields of reverse engineering and additive manufacturing techniques have led to the development of innovative solutions for personalized medicine. 3D technologies are quickly becoming a new treatment concept that hinges on the ability to shape patient-specific devices.Among the wide spectrum of medical applications, the orthopaedic sector is experiencing the most benefits. Several studies proposed modelling procedures for patient-specific 3D-printed casts for wrist orthoses, for example. Unfortunately, the proposed approaches are not ready to be used directly in clinical practice since the design of these devices requires significant interaction among medical staff, reverse engineering experts, additive manufacturing specialists and CAD designers. This paper proposes a new practical methodology to produce 3D printable casts for wrist immobilization with the aim of overcoming these drawbacks. In particular, the idea is to realize an exhaustive system that can be used within a paediatric environment. It should provide both a fast and accurate dedicated scanning of the hand-wrist-arm district, along with a series of easy-to-use semi-automatic tools for the modelling of the medical device. The system was designed to be used directly by the clinical staff after a brief training. It was tested on a set of five case studies with the aim of proving its general reliability and identifying possible major flaws. Casts obtained using the proposed system were manufactured using a commercial 3D printer, and the device’s compliance with medical requirements was tested. Results showed that the designed casts were correctly generated by the medical staff without the need of involving engineers. Moreover, positive feedback was provided by the users involved in the experiment.

Keywords: CAD | Cast modelling | Orthosis modelling | Personalized medicine | Reverse engineering

Abstract: The autologous ear reconstruction surgery, i.e. the reconstruction of the missing ear anatomy with autologous cartilage tissue in case of partial or complete absence of the auricular region, can be extremely complicated due to the unique shape and size of this anatomical region. Operations of sculpting and carving of the costal cartilage in order to realize the ear reproduction require a high degree of manual expertise and experience from the surgeon. The development of surgical aids that can provide the physician with guidelines during the reconstruction is being studied in the literature. However, state-of-the-art techniques do not represent the optimal solution and only partially help in the reconstruction process. They are based on two-or three-dimensional templates of the target anatomy, providing visual support, yet not helping in the actual reconstruction phase, or, in some cases, by providing active aid but not simplifying the procedure sufficiently. In this context, the option of creating custom cutting guides that could actively assist the surgeon both in the pre-operative planning phase and during the surgery was considered. The proposed approach involves the use of surgical guides adopted for the cutting and reconstruction of the individual anatomical elements involved. Through an iterative process carried out in collaboration with the surgeon the characteristics of the surgical guides have been defined. Subsequently, a method that can be applied systematically to model the cutting guides, ready to be printed with additive production techniques was defined. The procedure was designed with a view to a future semi-automatization of the entire process that could make the physician autonomous in the realization of the patient-specific guides.

Keywords: 3D Ear Templates | Autologous Ear Reconstruction | CAD modelling | Personalized Medicine | Reverse Engineering

Abstract: Additive Manufacturing is becoming a suitable production process for many industries: it is based on the idea of adding material layer by layer, in opposite to traditional manufacturing processes. This technology shows advantages as design flexibility, internal logistics minimization and product customization that make it perfect to produce customized parts and all the applications where low production rates occur. The production of spare parts for classic or luxury cars is a field where Additive Manufacturing can be adopted because of low demand and relevant costs to manage stocks keeping several different parts in the after-sales inventory. The photogrammetry technique has been investigated to obtain the 3D model of the component to be replaced and send it to decentralized production centers equipped with 3D printers. This approach can enhance by far the supply chain management for automotive spare parts.

Keywords: Additive Manufacturing | Automotive | Maintenance | Photogrammetry | Supply chain management

Abstract: A significant growth of Additive Manufacturing technology has been noticed in the last few decades due to its well-established advantages. This production process based on the idea of adding material layer by layer, instead of removing it, has several advantages such as: time reduction in the design-to-manufacturing cycle, capability to produce complex shapes in a single piece thus reducing the connections, and weight saving just to mention the main significant. On the same wave of enthusiasm, the research community is significantly focused on this technology and many contributions that are focused on the whole range of aspects connected to this manufacturing way are already available. However, Additive Manufacturing is in a development phase, and the design tools, the material portfolio and the production methodologies are still far from the optimum typical of mature technologies. This paper critically reviews the Additive Manufacturing advantages and weaknesses which nowadays limits its wider application; a discussion about how these problems could be solved is included, together with an outlook of the challenges the practitioners must face off from nowadays up to a time window of ten years.

Keywords: Additive Manufacturing | Design tools | Future challenges | Technology review | Topological optimization

Abstract: Nowadays, the contribution of the CAD modeling is not yet well exploited into the design of overhead lines. Even if some commercial tools are available, they are very similar to configuration tools with design rules related to reference normative. Sometimes, if 2D/3D CAD tools are employed, they are viewers or customized versions with specific features for the design of overhead lines. This situation limits the interoperability between the design of overhead lines and traditional software employed in the design of civil structures and infrastructures. Moreover, an information modeling approach is still lacking in current tools for the management of additional data about maintenance, cost, etc. In the context of overhead lines, the paper aims at showing an information modeling approach with a platform software which includes a configuration tool, a CAD module, an analytical-based solver, a costing tool, and a Finite Element Method solver. The CAD module is employed to define a 3D model including, as tag-objects, a set of information regarding the lifecycle design of overhead lines. Finally, a Finite Element Model solver enhances a second level of validation and enables advanced simulations.

Keywords: Computer-aided design | Configurations | Finite Element Model | Information Modeling | Overhead lines

Abstract: Design for Assembly is a strategy of design aimed at minimising product cost through design and process improvements. It led to a revolution in the manufacturing industry, resulting in reduced product costs, improved quality, shorter time to market, lower inventory, fewer suppliers and many other improvements. DFA is the method of design of the product for ease of assembly and in this context this paper presents an application of the strategy to a virtual case study represented by a two-way relief valve modelled by CAD. The aim of this paper was to test some DFA methods proposed by the literature and search for an efficient assembly of the virtual two-way relief valve reproduced by CAD, then verifying its assembly effectiveness. Some evaluation methods proposed by literature about the optimisation of design efficiency have been applied to the case study and this led to reconsider the design of some parts of the product. A final new design for the valve is proposed and the evaluation methods applied have been tested again on the new solution, in order to validate the results. A comparison between the original valve and the new version proposed by the authors has been made, in order both to check the feasibility of the new valve and in order to check the evaluation methods proposed.

Keywords: CAD | DfA | Optimization

Abstract: Environmental impact and recycling have been increasingly frequent topics in recent years. At the same time, the life cycle of products has increasingly become shorter, as the escalating competitive market requires new products in smaller pieces. From this perspective, the recovery of parts and products that are produced in this market system for subsequent reuse when they reach the end of their life cycle is essential. For these reasons, it has become critical that companies re-evaluate their product design with a view to the possible recovery of the parts that comprise their products and to create new products for the market. The following discussion was based on the study of design for disassembly (DfD), which is the analysis of industrial products aimed at optimizing disassembly in terms of time and costs. The application of the DfD to a case study of a gearbox has, among its main objectives, the search for the best disassembly sequence in terms of time and money. During the course of the study, augmented reality (AR) was used. Through the use of the Unity software and Vuforia package, it was possible to bring the gearbox back to AR and then simulate the disassembly sequence in AR.

Keywords: Augmented reality | Computer-aided design | Design for disassembly | Disassembly evaluation chart | Disassembly sequence planning | Gearbox | SolidWorks

Abstract: The work here described aims to offer a starting point for improving and making a generic maintenance process more efficient, first of all thanks to the use of a cutting-edge technology such as augmented reality, as a key tool that makes it possible and immediate to communicate to operators which are the fundamental stages of the maintenance process to be followed in the working area. Furthermore, thanks to the use of two methods applied in the context of the Design for Disassembly (later described), we also propose to search for all the possible sequences to get to the removal of a target component to be adjusted—in particular the optimal one (if it exists, in terms of time and costs) to be subsequently applied in an augmented reality “self-disassembly” model that can be viewed and followed by the operator, in a way that is still very little used today.

Keywords: Augmented reality | CAD | DFD | Industrial maintenance | Optimization

Abstract: This work aims to present an in-house low-cost computer-aided simulation (CASS) process that was recently implemented in the preoperative planning of complex osteotomies for limb deformities in children. Five patients admitted to the Unit of Paediatric Orthopaedics and Traumatology from April 2018 to December 2019, for correcting congenital or post-traumatic limb deformities were included in the study. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software, and the surgery was planned and simulated starting from the 3D digital model. 3D printed sterilizable models were fabricated using a low-cost 3D printer, and animations of the operation were generated with the aim to accurately explain the operation to parents. All procedures were successfully planned using our CASS method and the 3D printed models were used during the operation, improving the understanding of the severely abnormal bony anatomy. The surgery was precisely reproduced according to CASS and the deformities were successfully corrected in four cases, while in one case, the intraoperative intentional undersizing of the bone osteotomy produced an incomplete correction of a congenital forearm deformity. Our study describes the application of a safe, effective, user-friendly, and low-cost CASS process in paediatric orthopaedics (PO) surgery. We are convinced that our study will stimulate the widespread adoption of this technological innovation in routine clinical practice for the treatment of rare congenital and post-traumatic limb deformities during childhood.

Keywords: 3D modeling | Computer aided | Osteotomy | Paediatric orthopaedics | Preoperative planning | Surgery | Surgical simulation

Abstract: This work aims to analyze the characteristics and importance that design techniques for disassembly assume in the modern design phase of a mechanism. To this end, the study begins by considering a three-dimensional model of a gear motor, taken from the components of which the overall drawings are arranged and from the relief of those not available. Once the mechanism has been digitally reconstructed, the activity focuses on the study of the optimal disassembly sequence by comparing different methodologies, according to two evaluation criteria-minimizing the time taken and minimizing the number of tool changes necessary to complete the sequence. The main results of the work are (1) defining a standard methodology to improve disassembly sequence planning, (2) finding the best disassembly sequence for the specific component among the literature and eventually new methods, and (3) offering to the industrial world a way to optimize maintenance operations in mechanical products. Referring to the limitation of the present works, it can be affirmed that the results are limited to the literature explored and to the case study examined.

Keywords: CAD | Disassembly sequence planning | Globoid gear motor

Abstract: In brain tumor surgery, an appropriate and careful surgical planning process is crucial for surgeons and can determine the success or failure of the surgery. A deep comprehension of spatial relationships between tumor borders and surrounding healthy tissues enables accurate surgical planning that leads to the identification of the optimal and patient-specific surgical strategy. A physical replica of the region of interest is a valuable aid for preoperative planning and simulation, allowing the physician to directly handle the patient’s anatomy and easily study the volumes involved in the surgery. In the literature, different anatomical models, produced with 3D technologies, are reported and several methodologies were proposed. Many of them share the idea that the employment of 3D printing technologies to produce anatomical models can be introduced into standard clinical practice since 3D printing is now considered to be a mature technology. Therefore, the main aim of the paper is to take into account the literature best practices and to describe the current workflow and methodology used to standardize the pre-operative virtual and physical simulation in neurosurgery. The main aim is also to introduce these practices and standards to neurosurgeons and clinical engineers interested in learning and implementing cost-effective in-house preoperative surgical planning processes. To assess the validity of the proposed scheme, four clinical cases of preoperative planning of brain cancer surgery are reported and discussed. Our preliminary results showed that the proposed methodology can be applied effectively in the neurosurgical clinical practice both in terms of affordability and in terms of simulation realism and efficacy.

Keywords: 3D casting | 3D printing | Additive manufacturing | Brain | Cancer | Computer aided design | Neurosurgery | Physical simulation | Preoperative planning | Virtual planning

Abstract: Autologous ear reconstruction, i.e. the reconstruction of the outer ear from autologous cartilage tissue, is a very important surgery considering the psychosocial repercussions of an individual affected by microtia (i.e. the total or partial absence of the outer ear). The execution of this surgery can be very complex due to the unique characteristics of this anatomical region. In order to help the surgeon in the process of cutting and suturing, innovative surgical guides were designed that can transmit information about the shape and size of the anatomy to be reconstructed. This work lays the foundation for the creation of a semi-automatic and easy-to-use tool for the modeling of surgical guides. The goal is to make the hospital staff autonomous in the creation of instruments that can be used in pre-surgical simulation and during surgery.

Keywords: Autologous Ear Reconstruction | Bioengineering | Computer Aided Design | Medical Devices and Equipment | Microtia

Abstract: The most common clinical treatment for ear deformities or non-congenital abnormalities is the reconstruction of the missing geometry using autologous costal cartilage. The surgical procedure consists in cutting, sculpting and suturing harvested costal cartilage from the patient to recreate an ear shape which is symmetric to the contralateral ear. During chirurgical operation, surgeons needs an accurate 3D template as reference to reproduce the ear. For this purpose, reverse engineering and additive manufacturing techniques can be employed. Specifically, this works aims to develop a reliable, low-cost and user-friendly system, to acquire the healthy ear geometry in clinical environment avoiding head patient’s exposition to radiation (MRI, CT scan). An ideal acquisition setup and device have been selected to achieve accurate results. To this end, a casted model of an ear was created as reference, and the best setup was evaluated by comparing the obtained 3D reconstructions with it. Once the setup has been determined, the anatomies of five volunteers were acquired, to test the methodology on human subjects.

Keywords: 3D model | Ear | Microtia | Photogrammetry | RealSense D415

Abstract: In cranioplasty surgery, achieving an effective aesthetic shape restoration of the cranial vault is the most important issue to ensure a proper outcome in terms of social and psychological benefits for the patient. To date, the most advanced approach uses CT/MRI data to reconstruct, in a pre-operative stage, the 3D anatomy of the defective skull in order to design a patient-specific prosthesis. In the last years, several techniques have been proposed to improve the applicability of such approach in the clinical practice, but the analysis of the related literature shows still open issues, due to the wide anatomical variability and complexity of the craniofacial anatomy that needs to be retrieved. With the aim to overcome the State-of-the-Art drawbacks, a new semi-automatic hybrid procedure for repairing unilateral or quasi-unilateral (i.e. a single defect slightly passing the sagittal plane) cranial defects is presented. The novel approach is hybrid because a surface interpolation for filling the hole is used together with a template-based reconstruction guided by the healthy counterpart. The procedure, being landmark-independent and avoiding any patch adaptation, represents a valid alternative for the existing approaches also in terms of user's burden, requiring less time consuming and less cumbersome operations. In addition, a new evaluating technique able to measure the symmetry of the reconstruction as well as the continuity between patch and healthy bone is proposed to test the procedure performance. Several test cases have been then addressed to prove the effectiveness and repeatability of the proposed procedure in reconstructing large-size defects of the skull.

Keywords: CAD | Cranioplasty | Reverse Engineering | Skull Reconstruction

Abstract: Nowadays, smartphones and laptops equipped with cameras have become an integral part of our daily lives. The pervasive use of cameras enables the collection of an enormous amount of data, which can be easily extracted through video images processing. This opens up the possibility of using technologies that until now had been restricted to laboratories, such as eye-tracking and emotion analysis systems, to analyze users' behavior in the wild, during the interaction with websites. In this context, this paper introduces a toolkit that takes advantage of deep learning algorithms to monitor user's behavior and emotions, through the acquisition of facial expression and eye gaze from the video captured by the webcam of the device used to navigate the web, in compliance with the EU General data protection regulation (GDPR). Collected data are potentially useful to support user experience assessment of web-based applications in the wild and to improve the effectiveness of e-commerce recommendation systems.

Keywords: Affective Computing | Convolutional Neural Networks | Deep Learning | Gaze detection | User Experience

Abstract: The paper aims at providing an overview on the current automation level of geometric verification process with reference to some aspects that can be considered crucial to achieve a greater efficiency, accuracy and repeatability of the inspection process. Although we are still far from making this process completely automatic, several researches were made in recent years to support and speed up the geometric error evaluation and to make it less human-intensive. The paper, in particular, surveys: (1) models of specification developed for an integrated approach to tolerancing; (2) state of the art of Computer-Aided Inspection Planning (CAIP); (3) research efforts recently made for limiting or eliminating the human contribution during the data processing aimed at geometric error evaluation. Possible future perspectives of the research on the automation of geometric verification process are finally described.

Keywords: Automatic geometric verification | Computer-Aided Inspection Planning | Error evaluation | Feature Recognition | GPS standards | Model of specification for tolerancing | Partition

Abstract: Background: Sleep-Related Breathing Disorders are characterized by repeated episodes of complete or partial obstruction of the upper airway during sleep. Mandibular advancement devices represent a non-invasive treatment in reducing the number of respiratory events and in decreasing symptoms. The advancement extent of these devices is responsible for the mandibular roto-translation and its effects on the temporomandibular joint. Methods: This study defined a systematic method to assess the mandible roto translation that is caused by MADs according to a scan-to-CAD approach. Starting from a closed mouth position and simulating the oral appliance at different settings it was possible to define a local reference system that is useful for the evaluation of the mandibular roto-translation. This latter was then applied to evaluate the movements of the condyle and the mandibular dental arch. Results: MAD1 resulted in a reduced mouth opening and protrusion, while MAD2 enabled a higher degree of motion of the mandible useful for patients who need an important protrusion. Conclusions: The two devices present different dynamics. Results that are achievable employing this method can be directly used by practitioners in comparing MADs, as well as by researchers in evaluating MADs effects.

Keywords: Computer-aided design | Digital dentistry | Digital workflow | Mandibular advancement device | Obstructive sleep apnea syndrome

Abstract: This work proposes an innovative method for evaluating usersâ™ engagement, combining the User Engagement Scale (UES) questionnaire and a facial expression recognition (FER) system, active research topics of increasing interest in the humanâ"computer interaction domain (HCI). The subject of the study is a 3D simulator that reproduces a virtual FabLab in which users can approach and learn 3D modeling software and 3D printing. During the interaction with the virtual environment, a structured-light camera acquires the face of the participant in real-time, to catch its spontaneous reactions and compare them with the answers to the UES closed-ended questions. FER methods allow overcoming some intrinsic limits in the adoption of questioning methods, such as the non-sincerity of the interviewees and the lack of correspondence with facial expressions and body language. A convolutional neural network (CNN) has been trained on the Bosphorus database (DB) to perform expression recognition and the classification of the video frames in three classes of engagement (deactivation, average activation, and activation) according to the model of emotion developed by Russell. The results show that the two methodologies can be integrated to evaluate user engagement, to combine weighted answers and spontaneous reactions and to increase knowledge for the design of the new product or service.

Keywords: 3D simulator | CNN | Deep learning | Facial expression recognition | Human-computer interaction | User engagement scale | User-centered design

Abstract: The pre-concept design of the DEMO Vacuum Vessel is going on in view of the 2020 gate review; moreover the nuclear heat loads on the vessel inner shell were determined and found to be about one order of magnitude higher compared to ITER. A subsequent thermal-structural analysis of the vessel inner shell revealed high thermal stresses and a large temperature gradient through the inner shell thickness. Given the simultaneous occurrence of primary membrane stresses in the entire vessel inboard wall and, in proximity of the vessel ribs, high bending stresses due to the coolant pressure, a survey of all options within the design rules was required to identify the inter-dependencies of the individual stress limits (primary membrane, primary bending, thermal membrane plus bending). In order to face this kind of issues a detailed assessment on the design of the inboard wall of DEMO Vacuum Vessel has been conducted and is presented here. The current work evaluates both P and S type damages for the inboard wall of DEMO Vacuum Vessel in case of high nuclear heat load, vacuum vessel coolant pressure and toroidal field coil fast discharge. The elastic analysis method has been used to check the rules for prevention of both types of damage. The rules applied to prevent the aforementioned damages are compliant to Level A criteria, in case of negligible creep and negligible irradiation. In order to check the structural integrity of the inboard wall of DEMO VV against high thermal and mechanical loads, optimization structural analyses were performed and checked against the rules provided in the applicable design code (RCC MRx).

Keywords: Breeding blanket | CAD | DEMO | FEM | Ratcheting | Vacuum vessel

Abstract: In recent years, bone fracture detection and classification has been a widely discussed topic and many researchers have proposed different methods to tackle this problem. Despite this, a universal approach able to classify all the fractures in the human body has not yet been defined. We aim to analyze and evaluate a selection of papers, chosen according to their representative approach, where the authors applied different deep learning techniques to classify bone fractures, in order to select the strengths of each of them and try to delineate a generalized strategy. Each study is summarized and evaluated using a radar graph with six values: area under the curve (AUC), test accuracy, sensitivity, specificity, dataset size and labelling reliability. Plus, we defined the key points which should be taken into account when trying to accomplish this purpose and we compared each study with our baseline. In recent years, deep learning and, in particular, the convolution neural network (CNN), has achieved results comparable to those of humans in bone fracture classification. Adopting a correct generalization, we are reasonably sure that a computer-aided diagnosis (CAD) system, correctly designed to assist doctors, would save a considerable amount of time and would limit the number of wrong diagnoses.

Keywords: Bone fracture | CAD system | Deep learning | Neural network | Orthopedics | X-ray

Abstract: The optimization of the aeronautical assembly lines is one of the most challenging tasks in development of a new aircraft. To date the Aeronautical companies are founding project related to the optimization of the manufacturing processes, impacting on the reduction of the non-recurring costs. The work presented focuses on methods for the implementation of the determinate assembly approach in the case of manufacturing of aeronautical structures. The methods are based on the prediction of the coupling tolerances between airframe components in order to reduce the numbers of the features to be manufactured in assembly. All that to lead to a reduction of the non-recurring costs.

Keywords: Aeronautical products | Assembly process | CAD | Determinant Assembly | Determinate Assembly | Hole to hole | Statistical distribution | Tolerance prediction

Abstract: Nowadays, robots are heavily used in factories for different tasks, most of them including grasping and manipulation of generic objects in unstructured scenarios. In order to better mimic a human operator involved in a grasping action, where he/she needs to identify the object and detect an optimal grasp by means of visual information, a widely adopted sensing solution is Artificial Vision. Nonetheless, state-of-art applications need long training and fine-tuning for manually build the object's model that is used at run-time during the normal operations, which reduce the overall operational throughput of the robotic system. To overcome such limits, the paper presents a framework based on Deep Convolutional Neural Networks (DCNN) to predict both single and multiple grasp poses for multiple objects all at once, using a single RGB image as input. Thanks to a novel loss function, our framework is trained in an end-to-end fashion and matches state-of-art accuracy with a substantially smaller architecture, which gives unprecedented real-time performances during experimental tests, and makes the application reliable for working on real robots. The system has been implemented using the ROS framework and tested on a Baxter collaborative robot.

Keywords: Collaborative robotics | Deep learning | Industry 4.0 | Vision-guided robotic grasping

Abstract: Purpose: Suspected fractures are among the most common reasons for patients to visit emergency departments and often can be difficult to detect and analyze them on film scans. Therefore, we aimed to design a Deep Learning-based tool able to help doctors in diagnosis of bone fractures, following the hierarchical classification proposed by the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Foundation and the Orthopaedic Trauma Association (OTA). Methods: 2453 manually annotated images of proximal femur were used for the classification in different fracture types (1133 Unbroken femur, 570 type A, 750 type B). Secondly, the A type fractures were further classified into the types A1, A2, A3. Two approaches were implemented: the first is a fine-tuned InceptionV3 convolutional neural network (CNN), used as a baseline for our own proposed approach; the second is a multistage architecture composed by successive CNNs in cascade, perfectly suited to the hierarchical structure of the AO/OTA classification. Gradient Class Activation Maps (Grad-CAM) where used to visualize the most relevant areas of the images for classification. The averaged ability of the CNN was measured with accuracy, area under receiver operating characteristics curve (AUC), recall, precision and F1-score. The averaged ability of the orthopedists with and without the help of the CNN was measured with accuracy and Cohen's Kappa coefficient. Results: We obtained an averaged accuracy of 0.86 (CI 0.84−0.88) for three classes classification and 0.81 (CI 0.79−0.82) for five classes classification. The average accuracy improvement of specialists was 14 % with and without the CAD (Computer Assisted Diagnosis) system. Conclusion: We showed the potential of using a CAD system based on CNN for improving diagnosis accuracy and for helping students with a lower level of expertise. We started our work with proximal femur fractures and we aim to extend it to all bone segments further in the future, in order to implement a tool that could be used in every-day hospital routine.

Keywords: Bone fracture | Convolutional neural network | Deep Learning | Orthopaedics | X-Ray

Abstract: Purpose: The current study aimed to systematically review the literature addressing the use of deep learning (DL) methods in intraoperative surgery applications, focusing on the data collection, the objectives of these tools and, more technically, the DL-based paradigms utilized. Methods: A literature search with classic databases was performed: we identified, with the use of specific keywords, a total of 996 papers. Among them, we selected 52 for effective analysis, focusing on articles published after January 2015. Results: The preliminary results of the implementation of DL in clinical setting are encouraging. Almost all the surgery sub-fields have seen the advent of artificial intelligence (AI) applications and the results outperformed the previous techniques in the majority of the cases. From these results, a conceptualization of an intelligent operating room (IOR) is also presented. Conclusion: This evaluation outlined how AI and, in particular, DL are revolutionizing the surgery field, with numerous applications, such as context detection and room management. This process is evolving years by years into the realization of an IOR, equipped with technologies perfectly suited to drastically improve the surgical workflow.

Keywords: deep learning | intraoperative | neural network | surgical workflow

Abstract: In the original article, there was an error. A Conflict of Interest Statement was missed. A correction has been made to the Conflict of Interest section reporting the following detailed information.

Keywords: CBLO | ligaments | multibody | simulation | TPLO

Abstract: The aim of the research is to develop an azimuthing contra-rotating propeller for commercial applications with a power of 2000 kW. The thruster system is designed especially to be installed on high speed crafts (HSCs) for passenger transport with a cruising speed of about 35-40 knots. The topic is very useful because the azimuth thruster solutions currently do not find commercial applications in naval units for passenger transport. The latter are heavy, not very efficient from a hydrodynamic point of view and suitable for maximum cruising speed of about 18-20 knots. The study is interesting because among the advantages that these solutions provide are the possibility of transmitting very high torques and to guarantee a much longer life cycle. In more detail, the propulsion is realized by using a C-drive configuration, with a first mechanical transmission realized by using bevel gears mounted in a frame inside the hull, and a second transmission realized by bevel gears housed in a profiled hull at the lower end of a support structure. In the profiled hull will be installed the shafts of the propellers, in a contra-rotating configuration. In order to optimize the system before its industrial use, a close power loop test bench has been studied and designed to test high power transmissions. The test configuration allows to implement a back-to-back connection between two identical azimuthing contra-rotating propellers. Moreover, the particular test bench allows to size the electric motor simply based on the dissipated power by the kinematic mechanisms. Since the efficiency of these systems are very high, it is not necessary to use large electric motors, thus managing to contain the operating costs of the testing phase. The most significant disadvantage is the need to have two identical transmissions with consequent increase in installation costs. Through the back-to-back test bench it was possible to study the increase in efficiency compared to traditional systems.

Keywords: azimuthing contra-rotating propeller | CAD modeling | experimental test | finite element analysis | POD | Thruster

Abstract: The accurate location of the mid-sagittal plane is fundamental for the assessment of craniofacial dysmorphisms and for a proper corrective surgery planning. To date, these elaborations are carried out by skilled operators within specific software environments. Since the whole procedure is based on the manual selection of specific landmarks, it is time-consuming, and the results depend on the operators' professional experience. This work aims to propose a new automatic and landmark-independent technique which is able to extract a reliable mid-sagittal plane from 3D CT images. The algorithm has been designed to perform a robust evaluation, also in the case of large defect areas. The presented method is an upgraded version of a mirroring-and registration technique for the automatic symmetry plane detection of 3D asymmetrically scanned human faces, previously published by the authors. With respect to the published algorithm, the improvements here introduced concern both the objective function formulation and the method used to minimize it. The automatic method here proposed has been verified in the analysis of real craniofacial skeletons also with large defects, and the results have been compared with other recent technologies.

Keywords: Cranio-maxillofacial | Feature recognition | Medical imaging | Mid-sagittal plane | Symmetry analysis

Abstract: In this paper, a topological optimization procedure has been applied on a real component of the deck of a sailing multi-hull in order to find the internal shape that best save the material used in the manufacturing process without a relevant loss of structural rigidity. The multi-hull boat is a 16 feet length catamaran equipped with an asymmetric foil on both centerboards and with a symmetric foil on both rudders. The task of the analyzed object is to act as a cylindrical support for the screw that drives the rotation of the centerboard. The process adopted to manufacture this object is the Fused Deposition Modeling (FDM) technique, because of its high versatility and its relative low-cost impact. The aim of this work is to verify the applicability of FDM to structural naval component subjected to demanding loads during navigation and, at the same time, to investigate on the robustness of a topology optimization strategy in creating new shapes that recent additive manufacturing are able to create.

Keywords: CAD modeling | Fused deposition modeling | Topology optimization

Abstract: Among rising technology in medical field, methods and solutions of reverse engineering have a high impact as a new possibility for improving the traditional processes to design prosthesis and orthoses. Furthermore, reverse engineering solutions allows managing a big amount of patient's data, which can be also exploited for making the medical assessment during rehabilitation activities more objective and measurable. In particular, innovative technologies permit to manage big amount of data coming from several IT devices in order to better understand the correlation between technical aspects and human factors. These IT devices can be exploited through customized software applications, which are able to combine many data types (e.g. 3D scanners, motion capture systems and pressure sensors). In this research work, the attention is focused on the design of lower limb prosthesis around the digital human model of the patient. We present a virtual platform composed by an ad-hoc developed application for customizing the prosthesis according to patients' life style and medical knowledge as well as for visualizing pressure on patient's limb while evaluating his/her gait in a unique virtual knowledge-guided environment. Such applications are conceived to be usable by non IT experts, and all information are directly visualized on the digital human model of the amputee. The first part of the paper introduces the whole platform to design lower limb prosthesis using low-cost technologies. Then, the virtual gait analysis tool is described. Finally, tests and conclusion are discussed.

Keywords: 3D modelling | Health informatics | Marker-less motion capture system | Pressure data | User centered design

Abstract: Mathematical modeling of soft robots is complicated by the description of the continuously deformable three-dimensional shape that they assume when subjected to external loads. In this article we present the deformation space formulation for soft robots dynamics, developed using a finite element approach. Starting from the Cosserat rod theory formulated on a Lie group, we derive a discrete model using a helicoidal shape function for the spatial discretization and a geometric scheme for the time integration of the robot shape configuration. The main motivation behind this work is the derivation of accurate and computational efficient models for soft robots. The model takes into account bending, torsion, shear, and axial deformations due to general external loading conditions. It is validated through analytic and experimental benchmark. The results demonstrate that the model matches experimental positions with errors <1% of the robot length. The computer implementation of the model results in SimSOFT, a dynamic simulation environment for design, analysis, and control of soft robots.

Keywords: continuum robots | Cosserat rods | differential geometry | dynamics | mathematical modeling | soft robotics

Abstract: The goal of this paper is to disseminate the main results achieved within the FlexARM project. The project deals with advanced modeling techniques and predictive control strategies for flexible mechanical systems intended to be used in remote tasks inside advanced nuclear fusion reactors. This article aims at underlying the main aspect of the FlexARM methodology and paves the way towards future research in the field.

Keywords: DEMO remote maintenance | Flexible mechanical systems | Modeling | Vibration control

Abstract: In the current pre-concept phase of the European DEMO, integration studies of the systems in the Upper Port area are being carried out. In DEMO, the Upper Port of the Vacuum Vessel is extraordinarily large to allow for the vertical extraction of the Breeding Blanket segments. This requires a number of components inside and outside the port to be integrated with tight space constraints: The Upper Port structure and its annexes, the adjacent Toroidal and Poloidal Field Coils, the Thermal Shields, the piping connection to the Vacuum Vessel Pressure Suppression System, the Shield Plug and its inserts, the feeding pipework of the in-vessel components and part of the Breeding Blanket supporting structures. Apart from functional aspects, the design of these components is driven by considerations of structural integrity, maintainability and irradiation shielding, which are mutually competing in many areas. Several studies were conducted on the design of the Upper Port and the required configuration of the components within. The present article describes the development approach, the studied options and the respective results, the identified issues as well as the proposed engineering solutions, in particular with respect to the mechanical design of the Upper Port and the integrated Shield Plug.

Keywords: CAD | DEMO | Integration | Upper Port | Vacuum vessel

Abstract: In this work we present the latest progresses (September 2018) in the conceptual design of the main containment structures of DTT fusion reactor. The previous DTT baseline design is revised in terms of structural materials and overall reactor shape. The major change involves the vacuum vessel, which now foresees a welded double-wall stainless steel structure. The basic design includes eighteen sectors, with novel ports configuration for remote maintenance systems, diagnostics and heating equipment. New supports are designed for the first wall, which is conveniently segmented in view of assembly and remote replacement. The cryostat of the machine is conceived as a single-wall cylindrical vessel reinforced by ribs. The cryostat base is also in charge of supporting the vacuum vessel and the magnets system. A preliminary FEA analysis confirms that the main mechanical structure might withstand the design loads, in particular the ones resulting from possible plasma disruptions.

Keywords: CAD | DTT | EU-DEMO | FEM | Fusion reactor | Structural analysis

Abstract: Introduction and Objectives Fabrication processes for spinal orthoses require accurate three-dimensional (3D) models of the patients' trunk. Current methods for 3D reconstruction used in this field mainly include laser or structured light scanning; these methods are time expensive and invasive, especially for patients with partial disabilities. Therefore, a theoretically instant system for data acquisition of anatomical structure is highly desirable. The objective of this work is to show the feasibility of using digital photogrammetry for human body digitization to generate accurate 3D models of the patients' trunk for spinal orthoses fabrication. Materials and Methods Multiple synchronized two-dimensional images of the human torso are captured from different points of view using a photogrammetric scanner. A 3D model is generated using the state-of-the-art algorithms for point cloud and surface reconstruction. The digitized model is then used as input for the standard computer-aided design (CAD)/computer-aided manufacturing (CAM) process of fabrication. R4D from Rodin4D is used as prosthetics and orthotics CAD software. A robotic cell constituted by a six-axis KUKA KR 30-3 is used for milling a polyurethane foam. Vacuum forming is then adopted to generate the orthosis. Two spinal orthoses are fabricated using this approach and a classical one; then, they are evaluated using quantitative and qualitative metrics. Results The data acquisition using this approach lasts 50 milliseconds. The 3D reconstruction accuracy averages 0.21 ± 1.27 mm, which suits for the considered health care scenario. Results of the initial fitting of the orthoses fabricated with the presented method show better performances in terms of time (44%), product quality (35%), and patient experience (30%). Conclusions Digital photogrammetry can be used to enhance the data acquisition and data processing of anatomical surfaces for the CAD/CAM process of spinal orthoses. The data acquisition time, almost instant, allows an easy compliance of many patients. The data processing allows generating accurate models of the patient's body. The overall process generates orthoses with a better quality with respect to those manufactured using conventional procedures. ©

Keywords: CAD/CAM | fabrication techniques | photogrammetry | prosthetics and orthotics | spinal orthoses | three-dimensional reconstruction

Abstract: Kinematic modeling of continuum robots is challenging due to the large deflections that these systems usually undergone. In this paper, we derive the kinematics of a continuum robot from the evolution of a three-dimensional curve in space. We obtain the spatial configuration of a continuum robot in terms of exponential coordinates based on Lie group theory. This kinematic framework turns out to handle robotic helical shapes, i.e. spatial configurations with constant curvature and torsion of the arm.

Keywords: Continuum robotics | Differential geometry | Kinematics

Abstract: Compliant Mechanisms (CMs) are currently employed in several engineering applications requiring high precision and reduced number of parts. For a given mechanism topology, CM analysis and synthesis may be developed resorting to the Pseudo–Rigid Body (PRB) method, in which the behavior of flexible members is approximated via a series of rigid links connected by spring-loaded kinematic pairs. From a CM analysis standpoint, the applicability of a generic PRB model requires the determination of the kinematic pairs’ location and the stiffness of a set of generalized springs. In parallel, from a design standpoint, a PRB model representing the kinetostatic behavior of a flexible system should allow to compute the flexures’ characteristics providing the desired compliance. In light of these considerations, this paper describes a Computer-Aided Design/Engineering (CAD/CAE) framework for the automatic derivation of accurate PRB model parameters, on one hand, and for the shape optimization of complex-shape flexures comprising out-of-plane displacements and distributed compliance. The method leverages on the modelling and simulation capabilities of a parametric CAD (i.e. PTC Creo) seamlessly connected to a CAE tool (i.e. RecurDyn), which provides built-in functions for modelling the motion of flexible members. The method is initially validated on an elementary case study taken from the literature. Then, an industrial case study, which consists of a spatial crank mechanism connected to a fully-compliant four-bar linkage is discussed. At first, an initial sub-optimal design is considered and its PRB representation is automatically determined. Secondly, on the basis of the PRB model, several improved design alternatives are simulated. Finally, the most promising design solution is selected and the dimensions of a flexure with non-trivial shape (i.e. hybrid flexure) is computed. This technique, which combines reliable numerical results to the visual insight of CAD/CAE tools, may be particularly useful for analyzing/designing spatial CMs composed of complex flexure topologies.

Keywords: CAD/CAE integration | Distributed compliance | Pseudo rigid body models | Shape optimization | Spatial compliant mechanisms

Abstract: Position-controlled servo-systems mostly make use of electric rotary motors and gearboxes and, if necessary, a transmission mechanism to convert rotary into linear motion. Even so, especially in the field of automatic machines for packaging, it should be highlighted that most of the required movements are usually linear, so that Linear Electric Motors (LEM) should somehow represent a more convenient solution for designers. LEM can directly generate the required trajectory avoiding any intermediate mechanism, thus potentially minimizing the number of linkages/mechanical parts and, therefore, the undesired backlash and compliance that come along. On the other hand, particularly within small-medium enterprises, LEM may be rarely employed despite obvious advantages, mostly due to their high-cost as compared to rotary actuators and the lack of knowledge of the achievable performance. In light of these considerations, the present paper reports an industrial case study where an automatic machine for packaging, comprising distributed actuation and several tasks requiring a linear motion, has been completely redesigned employing different kind of LEM (i.e. iron-core and iron-less). Such machine architecture is compared to a “traditional” design where brushless gearmotors are coupled to linkage systems. The paper mainly focuses on the selection criteria for the LEM system and on the engineering tools employed during the different design stages. Qualitative and quantitative conclusions are finally drawn, which may provide useful hints for designers that are willing to actually employ LEM-based solutions in an industrial scenario.

Keywords: CAD/CAE | Engineering Design Methods and Tools for Industry 4.0 | High Precision Manufacturing | Modelling | Simulation

Abstract: Pectus Arcuatum, a rare congenital chest wall deformity, is characterized by the protrusion and early ossification of sternal angle thus configuring as a mixed form of excavatum and carinatum features. Surgical correction of pectus arcuatum always includes one or more horizontal sternal osteotomies, consisting in performing a V-shaped horizontal cutting of the sternum (resection prism) by means of an oscillating power saw. The angle between the saw and the sternal body in the V-shaped cut is determined according to the peculiarity of the specific sternal arch. The choice of the right angle, decided by the surgeon on the basis of her/his experience, is crucial for a successful intervention. The availability of a patient-specific surgical guide conveying the correct cutting angles can considerably improve the chances of success and, at the same time, reduce the intervention time. The present paper aims to propose a new CAD-based approach to design and produce custom-made surgical guides, manufactured by using additive manufacturing techniques, to assist the sternal osteotomy. Starting from CT images, the procedure allows to determine correct resection prism and to shape the surgical guide accordingly taking into account additive manufacturing capabilities. Virtually tested against three case studies the procedure demonstrated its effectiveness.

Keywords: Biomedical devices | CAD | Design for additive manufacturing | Medical imaging

Abstract: 3D models of submerged structures and underwater archaeological finds are widely used in various and different applications, such as monitoring, analysis, dissemination, and inspection. Underwater environments are characterised by poor visibility conditions and the presence of marine flora and fauna. Consequently, the adoption of passive optical techniques for the 3D reconstruction of underwater scenarios is a highly challenging task. This article presents a performance analysis conducted on a multi-view technique that is commonly used in air in order to highlight its limits in the underwater environment and then provide guidelines for the accurate modelling of a submerged site in poor visibility conditions. A performance analysis has been performed by comparing different image enhancement algorithms, and the results have been adopted to reconstruct an area of 40 m2 at a depth of about 5 m at the underwater archaeological site of Baiae (Italy).

Keywords: 3D reconstruction | Image enhancement | Underwater Cultural Heritage | Underwater imaging

Abstract: Reverse Engineering (RE) may help tolerance inspection during production by digitalization of analyzed components and their comparison with design requirements. RE techniques are already applied for geometrical and tolerance shape control. Plastic injection molding is one of the fields where it may be applied, in particular for die set-up of multi-cavities, since no severe accuracy is required for the acquisition system. In this field, RE techniques integrated with Computer-Aided tools for tolerancing and inspection may contribute to the so-called “Smart Manufacturing”. Their integration with PLM and suppliers' incoming components may set the information necessary to evaluate each component and die. Intensive application of shape digitalization has to front several issues: accuracy of data acquisition hardware and software; automation of experimental and post-processing steps; update of industrial protocol and workers knowledge among others. Concerning post-processing automation, many advantages arise from computer vision, considering that it is based on the same concepts developed in a RE post-processing (detection, segmentation and classification). Recently, deep learning has been applied to classify point clouds, considering object and/or feature recognition. This can be made in two ways: with a 3D voxel grid, increasing regularity, before feeding data to a deep net architecture; or acting directly on point cloud. Literature data demonstrate high accuracy according to net training quality. In this paper, a preliminary study about CNN for 3D points segmentation is provided. Their characteristics have been compared to an automatic approach that has been already implemented by the authors in the past. VoxNet and PointNet architectures have been compared according to the specific task of feature recognition for tolerance inspection and some investigations on test cases are discussed to understand their performance.

Keywords: Deep learning | Injection molding | PointNet | Reverse engineering | Tolerance inspection

Abstract: Interventions of ancient bronze statues restoration may last long periods, involving several activities from material and structural analysis to set-up of museum exhibitions, passing through reconstruction of fragments. In this paper, we describe procedures and methods used for evaluation of the current posture of “Principe Ellenistico”. In fact, the statue seems to present some inaccuracies, in the fragments assembly, made during the last restoration activity (one of this effect is clearly observed in the spear inclination). The final aims are: (1) evaluation of differences among the postures before and after the last restoration; (2) recognition of the original fragments embedded in a previous restoration; and (3) the study of a possible better positioning of them. Methods applied are related to feature recognition on acquired point clouds, image analysis through control points and algorithms to find centerline of the elements that could need to be repositioned. In the final part, a concept design for a new inner-support is presented, giving the possibility to avoid assembly inaccuracies. Future developments are presented as the prospect of additive manufacturing the support, firstly with a FDM prototype and then through SLM or similar technologies.

Keywords: 3D-reconstruction | Bronze statue restoration | Cultural heritage | Feature recognition | Virtual prototyping

Abstract: The research reported in this paper applies an explicit non-linear FEA solver to simulate the interaction between a clamp and a hyper-elastic material that aims to mimic the biological tissue of the colon. More in detail, the paper provides new results as a continuation of a previous works aimed at the evaluation of this solver to manage contact and dynamic loading on complex, multiple shapes. Results concern with the evaluation of the contact force during clamping, thus to the assessment of the force-feedback. The analysis is carried out on two geometries, using the hyper-elastic Mooney-Rivlin model for the mechanical behavior of the soft tissues. A pressure is applied on the colon to simulate the surgical clamp, which goes progressively in contact with tissue surface. To assess FEA criticality, and, then, its feasibility, the stress-strain and the contact force are analysed according to geometrical model and thickness variation, leaving the pressure constant. Doing so, their effect on the force-feedback can be foreseen, understanding their role on the accuracy of the final result.

Keywords: Computer assisted surgical planning | Finite element analysis | Segmentation | Soft tissues simulations

Abstract: The preservation status of an underwater cultural site can be determined as the combination of two primary factors, namely the site physical integrity, which results from the past and present interaction of the site itself with the biological/chemical agents located in the surrounding environment, and the exposure of the site to human-related threats. Methods to survey underwater archaeological sites have evolved considerably in the last years in order to face the challenges and problems in archaeological prospection, documentation, monitoring, and data collection.This paper presents a case-study of an archaeological documentation campaign addressed to study and monitor the preservation status of an underwater archaeological site by combining the quantitative measurements coming from optical and acoustic surveys with the study of biological colonization and bioerosion phenomena affecting ancient artefacts. In particular, we present the first results obtained in the survey and documentation campaign carried out during the spring - summer 2018 in the "Nymphaeum of Punta Epitaffio" located in the Marine Protected Area - Underwater Park of Baiae (Naples).

Keywords: 3D Imaging | 3D Mapping | Baiae Archaeological Park | Photogrammetry | Underwater Archaeology

Abstract: Although the CAD parameters allow to update easily the geometrical model, the numerical models updating into Finite Elements (FE) software with different mesh result to be often heavy, due to the necessity both to create new mesh and to make usually time consuming and complex CAE calculations for updating the loading conditions. The aim of the present research is to devise a reliable methodology and at the same time to reduce computational burden in the shape optimization studies of mechanical components. In particular, an integrated Multibody (MB) and Mesh-Morphing (MM) approach was developed to perform shape optimization, in order to reduce maximum tensions. Using the RBF Morph ACT Extension plugin implemented in the commercial solver FEM ANSYS® Mechanical vers. 18.2 along with the commercial MB software MSC ADAMS® vers. 2017, shape optimizations can be obtained in a very short time, by acting directly at the mesh so updating node positions and mesh elements geometry without bringing different geometrical models of the component into the FE environment. To validate the methodology, a crankshaft for a high performance Internal Combustion Engine (I.C.E.) was chosen, as case study, to optimize the fillet zones between web and pin.

Keywords: Crankshaft | FEA | Fillet zones | Multibody | Stress analysis

Abstract: Background: The integration of computer-aided design/computer-aided manufacturing (CAD/CAM) tools and medicine is rapidly developing for designing medical devices. A novel design for a 3D-printed patient-specific surgical template for thoracic pedicle screw insertion, using a procedure based on reverse engineering, is presented. Methods: The surgeon chooses the entry point on the vertebra. The optimal insertion direction and the size of the screws are defined via an algorithm on the basis of a patient-specific vertebra CAD model. The template features an innovative shape for a comfortable and univocal placement and a novel disengaging device. Results: Three spinal fusions were performed to test the template. Excellent results were achieved in terms of the accuracy of the screw positioning, reduction in surgery duration, and number of X-rays. Conclusions: A novel design for a customized, 3D-printed surgical template for thoracic spinal arthrodesis was presented, and improvements in terms of precision, duration, and safety were achieved without changing the standard procedure.

Keywords: 3D imaging | additive manufacturing | bone | computer-assisted surgery | imaged guided surgery | in vivo | modelling | pedicle screw fixation | screw direction optimization | spine | surgical template | thoracic | thoracic spinal arthrodesis | X-ray minimization

Abstract: Aim of this paper is to present a methodology useful to optimize the geometry of the blades of a small-size wind turbine which are obtained from a circular pipe: an optimal chord distribution and airfoil sweep can be obtained with a proper cutting path. A strong reduction in manufacturing costs and time can be achieved for blades which are a critical element in wind turbine systems, especially in case of renewable plants in developing countries. An algorithm has been developed to obtain the shape of the blades and wind turbine performances are computed by the Blade-Element Method, due to its low computational simplicity; the XFoil tool has been used to compute the aerodynamic of the blades. Heuristic algorithms have been applied to obtain a feasible design solution assuring the best efficiency of the wind turbine. Also structural considerations are kept into account to provide a feasible configuration able to withstand the forces acting on the rotating blades. Results obtained suggest that an optimal design of such a kind of blades can be obtained thanks to this methodology. The mathematical framework developed for the optimization is efficient and the heuristics algorithms allow the convergence to feasible configurations. The computing time is compatible with a practical application of the method also in industries.

Keywords: CAD | Design | Multidisciplinary optimization | Particle swarm algorithm | Wind turbine

Abstract: The final subject position is often the only evidence in the case of the fall of a human being from a given height. Foreseeing the body trajectory and the respective driving force may not be trivial due to the possibility of rotations and to an unknown initial position and momentum of the subject. This article illustrates how multibody models can be used for this aim, with specific reference to an actual case, where a worker fell into a stair well, prior to stair mounting, and he was found in an unexpected posture. The aim of the analysis was establishing if this worker was dead in that same place, if he had been pushed, and which was his initial position. A multibody model of the subject has been built (“numerical android”), given his stature and his known mass. Multiple simulations have been performed, following a design of experiments where various initial positions and velocity as well as pushing forces have been considered, while the objective function to be minimized was the deviation of the numerical android position from the actual worker position. At the end of the analysis, it was possible to point how a very limited set of conditions, all including the application of an external pushing force (or initial speed), could produce the given final posture with an error on the distance function equal to 0.39 m. The full analysis gives a demonstration of the potentiality of multibody models as a tool for the analysis of falls in forensic inquiries.

Keywords: accident | android | biomechanics | crime | doe | fall | forensic | multibody

Abstract: In an increasingly competitive business world, the “time to market” of products has become a key factor for business success. There are different techniques that anticipate design mistakes and launch products on the market in less time. Among the most used methodologies in the design and definition of the requirements, quality function deployment (QFD) and design for Six Sigma (DFSS) can be used. In the prototyping phase, it is possible to address the emerging technology of additive manufacturing. Today, three-dimensional printing is already used as a rapid prototyping technique. However, the real challenge that industry is facing is the use of these machineries for large-scale production of parts, now possible with new HP multi-fusion. The aim of this article is to study the entire product development process taking advantage of the most modern models and technologies for the final realization of a case study that involves the design and prototyping of an innovative multifunctional fan (lamp, aroma diffuser and fan) through the Multi Jet Fusion of HP. To begin with, issues related to the DFSS, the QFD and their application to identify the fan requirements are explored. Once the requirements have been defined, the modern CAD design systems and the CAE systems for the validation of the case study will be analyzed and applied. Finally, HP’s Multi Jet Fusion methodology and design rules for additive manufacturing will be analyzed in detail, trying to exploit all the positive aspects it offers.

Keywords: CAD | CAE | Design for additive manufacturing | Design for six sigma | FEA | Multi jet fusion | Product development | QFD | Rapid prototyping

Abstract: In an increasing number of aggressive enterprise world, “time to market” concerning products has come to be a solution element because of enterprise success. There are exceptional techniques so expect layout mistakes or open products concerning the need between much less time. Among the most used methodologies in the design and setting about stability the requirements, Quality Function Deployment (QFD) and Design for Six Sigma (DFSS) execute remain used. In the prototyping phase, such is feasible in imitation of tackle the rising science regarding additive manufacturing. Today, three-dimensional stamping is in the meanwhile used as a rapid prototyping technique. However, the actual challenge that enterprise is going through is the use of these machineries for large-scale production about parts, at last viable along current HP Multi fusion. The aim of this article is to study the interactive design and engineering applied to the entire product development process taking advantage of the most modern models and technologies for the final realization of a case study that involves the design and prototyping of an innovative multifunctional fan (Lamp, Aroma Diffuser and fan) through the Multi Jet Fusion of HP. To begin with, issues related to the DFSS, the QFD and their application to identify the fan requirements are explored. Once the requirements have been defined, the modern CAD design systems and the CAE systems for the validation of the case study will be analyzed and applied. Finally, HP’s Multi Jet Fusion methodology and design rules for additive manufacturing will be analyzed in detail, trying to exploit all the positive aspects it offers.

Keywords: CAD | CAE | Design for additive manufacturing | Design for Six Sigma | FEA | Multi jet fusion | Product development | QFD | Rapid prototyping

Abstract: This paper defines a systematic workflow for production cost estimation of sheet metal stamped components. The approach represents a solution toward the adoption of Design to Cost methods during early product design. It consists in a sequence of steps that, starting from a 3D CAD model with annotations (material, roughness and tolerances) and production information (batch and production volume) leads to the manufacturing cost through an analytic cost breakdown (raw material, stamping and accessory processes, setup and tooling). The calculation process mainly consists in a first step where geometric algorithms calculate the sheet metal blank (dimensions, shape, thickness) and specific product features (e.g. flanges, louvers, embossing, etc.). The following steps allow to calculate the raw material, the stamping process and the process-related parameters, which are the manufacturing cost drivers (e.g. press, stamping rate/sequence/force and die dimensions/weight). The manufacturing cost is the sum of the previous calculated items. Testing the approach for three different components, the average absolute deviation measured between the estimated and actual cost was less than 10% and such a result looks promising for adopting this method for evaluating alternative design solutions.

Keywords: Cost estimation | Design to cost | Feature recognition | Sheet metal stamping

Abstract: Recently, the approach that defines the total life cycle assessment (LCA) and the end of life (EoL) in the early design phases is becoming even more promising. Literature evidences many advantages in terms of the saving of costs and time and in the fluent organization of the whole design process. Design for disassembly (DfD) offers the possibility of reducing the time and cost of disassembling a product and accounts for the reusing of parts and of the dismantling of parts, joints, and materials. The sequence of disassembly is the ordered way to extract parts from an assembly and is a focal item in DfD because it can deeply influence times and operations. In this paper, some disassembly sequences are evaluated, and among them, two methods for defining an optimal sequence are provided and tested on a case study of a mechanical assembly. A further sequence of disassembly is provided by the authors based on experience and personal knowledge. All three are analyzed by the disassembly order graph (DOG) approach and compared. The operations evaluated have been converted in time using time measurement units (TMUs). As result, the best sequence has been highlighted in order to define a structured and efficient disassembly.

Keywords: CAD | Disassembly | DOG | Sequence | TMU | Tools

Abstract: This paper presents a software based on an innovative Convolutional Neural Network model to recognize the six Ekman's universal emotions from the photos of human faces captured in the wild. The CNN was trained using three different datasets already labeled and merged after making them homogeneous. A comparison among different types of CNN architectures using the Keras framework for Python language is proposed and the evaluation results are presented.

Keywords: convolutional neural network | deep learning | emotion recognition

Abstract: Purpose: The purpose of this paper is to describe an innovative Parametric and Adaptive Slicing (PAS) technique to be used for generating material addition paths along three-dimensional surfaces. Design/methodology/approach: The method is grounded on the possibility to generate layers starting from multiple reference surfaces (already available in the model or created on purpose). These are used for mathematically deriving a family of parametric surfaces whose shape and spacing (the layer thickness) can be tuned to get the desired aesthetic, technical and functional characteristics. The adhesion among layers is obtained guaranteeing a smooth transition among these surfaces. Findings: The examples described in the paper demonstrate that the PAS technique enables the addition of the material along non-planar paths and, hence, the elimination of the staircase effect. In addition, objects printed using this technique show improved mechanical properties with respect to those printed using standard planar layers. Research limitations/implications: As the method allows a local control of the material addition/deposition, it can be used to design the mechanical behavior of the objects to be printed. Originality/value: The technique proposed in this paper overcomes the limitations of currently available adaptive and curved layer slicing strategies, by introducing the possibility to generate layers with a non-constant thickness whose shape morphs smoothly from one layer to another.

Keywords: Additive manufacturing | Computer aided design | Computer aided manufacturing | Curved layer | Design for additive manufacturing | Geometrical modelling

Abstract: This study proposes a novel occlusions detection and restoration strategy. The aim is to success with 3D face recognition even when faces are partially occluded by external objects. The method, which relies on geometrical facial properties, is designed for managing two types of facial occlusions (eye and mouth occlusions due to hands). First occlusions are detected and (if present) classified, by considering their effects on the 3D points cloud. Then, the occluded regions are progressively removed, and finally, the non-occluded symmetrical regions are used to restore the missing information. After the restoration process, face recognition is performed relying on the restored facial information and on the localized landmarks. The landmarking methodology relies on derivatives and on 12 differential geometry descriptors. The discriminating features adopted for facial comparison include shape index histograms, Euclidean and geodetical distances between landmarks, facial curves, and nose volume. Obtained recognition rates, evaluated on the whole Bosphorus database and on our private dataset, ranging from 92.55 to 97.20% depending on the completeness of data.

Keywords: 3D face | Differential geometry | Face analysis | Face recognition | Feature extraction

Abstract: Surgical interventions for jaw reconstruction require the design and the production of surgical guides that allow the surgeon to operate quickly and accurately. In some cases, the reconstruction is performed by inserting a prothesis, thus operating exclusively on the jaw, while in other cases the reconstruction is performed by withdrawing and inserting part of the fibula in place of the original jaw bone. This project aims to develop a procedure that allows 3D modeling of the surgical guides necessary for surgical intervention. The idea is to find a surgical guide archetype, a starting shape for the surgeon so that the cutting planes can be oriented without the surgical guide having to be redesigned from scratch for every single patient. The first step of the procedure is the segmentation, performed applying the thresholding operation on the images provided by magnetic resonance MR in order to identify the region of interest (ROI). The second step is the reconstruction of the 3D model, so that a mesh is obtained from 2D images. Subsequently the mesh is post-processed and the cutting plans along which the surgeon will intervene are defined.

Keywords: 3D modeling | 3D reconstruction | Maxillofacial surgery | Surgical guides

Abstract: The optimization of the aeronautical structures manufacturing is one of the most challenging tasks in development of a new aircraft. Nowadays, aeronautical industries are supporting researches deal with the development of new assembly approaches which aim at increasing efficiency and reducing cost of the processes. The work here presented focused on definition of a Jig-less assembly procedure of the 'Integrated Main Landing Gearbox' (ITEM B). The project aims to develop a new generation of Lower Center Fuselage with an innovative landing system integrated in the fuselage itself. The ambition of ITEMB is the creation of a single integrated structure in composite material of the gear bay that reduces assembly costs, optimizing and integrating the entire design, construction and maintenance of the aircraft. The approach here described is based on the integration of different engineering disciplines, as such as the tolerance statistical prediction, the ergonomics, digital human modeling, manufacturing and measurement technologies. In particular, through an appropriate ergonomic analysis, an innovative assembly process of the gear bay was developed and optimized in a virtual environment pointing out the advantages and disadvantages with respect to a traditional assembly cycle. The assembly process is based also on the implementation of the assembly tolerance prediction.

Keywords: CAD | Determinant Assembly | Ergonomics | Jig-less approach | Tolerance statistical prediction | Variational assemblies

Abstract: Aboveground biomass (AGB) is a parameter commonly used for assessing and monitoring primary productivity of grassland communities. Destructive AGB measurements, although accurate, are time-consuming and do not allow for repeated measurements as required by monitoring protocols. Structure-from-motion (SfM) photogrammetry has been proved to be a reliable tool for rapid and not destructive AGB estimations in grass systems. Three-dimensional (3D) models of fourteen 1 × 1 m2 pasture plots were reconstructed and AGB volume measured under several measurement settings. Volume-based AGB measures were regressed to AGB values resulting from destructive methods to identify the measurement settings that show the best fit. Furthermore, 3D models of four mountain pasture plots were reconstructed in May, July, and August. Models relative to the same plot were aligned and their relative difference measured to produce a diachronic canopy variation model (DCVM). On the measured volume (Vd), the coefficient of density (cρ) was applied to adjust the volume values (Vadj) in relation to variation due to different DCVM point densities. The measurement setting for AGB volume estimations strongly influenced their correlation with traditional AGB scores. The best fit was obtained selecting 1 mm grid cell size and minimum point height distance. Such options were then selected to measure the DCVM. Adjusted volumes were fully correlated with the average point distance. Three plots revealed higher rates of AGB in the spring compared to summer season, as justified by the summer aridity constraints affecting vegetation productivity in Mediterranean areas. In one plot, we found an anomalous seasonal pattern, showing an AGB reduction in spring, which can be correlated with grazing, that promoted a subsequent increment in summer. Our study indicates that image-based photogrammetric techniques allow for reliable non-destructive measurements of surface biomass in diachronic analyses, offering a valuable tool for evaluating occurrence, magnitude, and spatial patterns of variations of community primary productivity over time. Diachronic canopy variation model produced congruent patterns of inter-seasonal canopy variations proving to be a useful tool for analyzing local disturbance to vegetation canopy caused by grazing.

Keywords: biomass | coefficient of density | diachronic variation | local disturbance | non-destructive measurements | pasture community | photogrammetry | structure-from-motion

Abstract: The aim of the present work is disclosing a model suitable to provide a new tool for the synthesis of mechanisms and structures. Firstly, a framework will be introduced for the representation of a particular class of mechanisms: compliant mechanisms. For this purpose, the constitutive elements and the relations between the elements are organized in a taxonomy, similar to the ones used for the definition of ontologies. Ontologies have been taken as inspiration for the construction of the general schema for two main reasons: the first one is the need of consistency in the physical models, in order to obtain reliable results. The second reason is that one of the main features of ontologies is modularity, which means that they may be reused, and implemented for the creation of widest classifications. In the proposed framework, mechanisms result from the combination of the constitutive elements, according to a certain topology. The topologies are generated taking in account the defined feasible relations between elements. Once the mechanisms are defined, their behavior, in terms of mechanical response, is calculated and implemented in the schema as well. Finally, a classification of the evaluated mechanisms is provided, correlating the mechanical behavior of the mechanisms to the topological arrangement of their elements, or, in other words, their geometry. This classification may be synthetized in a table which may be query setting the mechanical response (set of deformation allowed or denied as response of a set of generalized forces). The result of the query is the indication of the topology of the mechanism that fits the mechanical response best. The proposed table is a design tool actually, suggesting the constructive form to the designer starting from a functional requirement. Moreover, considering the table of topologies and the physical model with which it was generated, they constitute a synthesis tool for that class of mechanisms, and, ultimately, a topology, and size optimization tool.

Keywords: Control | Modeling | Modeling and simulation | Optimization | Robotics

Abstract: Anterior cruciate ligament (ACL) deficiency can result in serious degenerative stifle injuries. Although tibial plateau leveling osteotomy (TPLO) is a common method for the surgical treatment of ACL deficiency, alternative osteotomies, such as a leveling osteotomy based on the center of rotation of angulation (CBLO) are described in the literature. However, whether a CBLO could represent a viable alternative to a TPLO remains to be established. The aim of this study is to compare TPLO and CBLO effectiveness in treating ACL rupture. First, a computational multibody model of a physiological stifle was created using three-dimensional surfaces of a medium-sized canine femur, tibia, fibula and patella. Articular contacts were modeled by means of a formulation describing the contact force as function of the interpenetration between surfaces. Moreover, ligaments were represented by vector forces connecting origin and insertion points. The lengths of the ligaments at rest were optimized simulating the drawer test. The ACL-deficient model was obtained by deactivating the ACL related forces in the optimized physiological one. Then, TPLO and CBLO treatments were virtually performed on the pathological stifle. Finally, the drawer test and a weight-bearing squat movement were performed to compare the treatments effectiveness in terms of tibial anteroposterior translation, patellar ligament force, intra-articular compressive force and quadriceps force. Results from drawer test simulations showed that ACL-deficiency causes an increase of the anterior tibial translation by up to 5.2 mm, while no remarkable differences between CBLO and TPLO were recorded. Overall, squat simulations have demonstrated that both treatments lead to an increase of all considered forces compared to the physiological model. Specifically, CBLO and TPLO produce an increase in compressive forces of 54% and 37%, respectively, at 90◦ flexion. However, TPLO produces higher compressive forces (up to 16%) with respect to CBLO for wider flexion angles ranging from 135◦ to 117◦ . Conversely, TPLO generates lower forces in patellar ligament and quadriceps muscle, compared to CBLO. In light of the higher intra-articular compressive force over the physiological walking range of flexion, which was observed to result from TPLO in the current study, the use of this technique should be carefully considered.

Keywords: CBLO | Ligaments | Multibody | Simulation | TPLO

Abstract: Objective: To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. Methods: Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch (‘long branch’ and ‘short branch’) in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. Results: With reference to the ‘long branch’ model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with the exception of the initial condition (1% bone maturation) where the implant is not osseointegrated. By contrast, implant displacements become relevant in the ‘short branch’ model, unless osseointegration level is beyond 20%. The difference between resonance frequency at whole bone maturation and resonance frequency at 1% bone maturation remained lower than 6.5% for all modes, with the exception of the third mode of vibration in the ‘D’ implant where this difference reached 9.7%. With reference to the ‘short branch’ considering the first mode of vibration, 61–68% of the frequency increase was achieved at 10% osseointegration; 72–79% was achieved at 20%; 89–93% was achieved at 50% osseointegration. The pattern of the natural frequency versus the osseointegration level is similar among different modes of vibration. Significance: Resonance frequencies and their trends towards osseointegration level may differ between implant designs, and in different boundary conditions that are related to implant position inside the mandible; tapered implants are the most sensitive to bone maturation levels, small implants have very little sensitivity. Resonance frequencies are less sensitive to bone maturation level beyond 50%.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Implant stability | Material properties | Osseointegration | Reverse engineering

Abstract: Objectives: To assess conceptual designs of dental posts consisting of polyetherimide (PEI) reinforced with carbon (C) and glass (G) glass fibers in endodontically treated anterior teeth. Methods: 3D tessellated CAD and geometric models of endodontically treated anterior teeth were generated from Micro-CT scan images. Model C-G/PEI composite posts with different Young's moduli were analyzed by Finite Element (FE) methods post A (57.7 GPa), post B (31.6 GPa), post C (from 57.7 to 9.0 GPa in the coronal–apical direction). A load of 50 N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum principal stress distribution was determined along the post and at the interface between the post and the surrounding structure. Results: Post C, with Young's modulus decreasing from 57.7 to 9.0 GPa in the coronal–apical direction, reduced the maximum principal stress distribution in the restored tooth. Post C gave reduced stress and the most uniform stress distribution with no stress concentration, compared to the other C-G/PEI composite posts. Significance: The FE analysis confirmed the ability of the functionally graded post to dissipate stress from the coronal to the apical end. Hence actual (physical) C-G/PEI posts could permit optimization of stress distributions in endodontically treated anterior teeth.

Keywords: CAD | Dental materials | Design | Endodontic treatment | Finite Element analysis | Image analysis

Abstract: Objective: To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. Methods: Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS® v. 17.0. Static linear analyses were also carried out. Results: ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. Significance: The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Material properties | Osseointegration | Plateau implants

Abstract: A new method for secondary features segmentation, performed on high-density tessellated geometric models, is proposed. Four types of secondary features are considered: fillets, rounds and grooves. Sharp edges are also recognised. The method is based on an algorithm that analyses the principal curvatures. The nodes, potentially attributable to a fillet of given geometry, are those with a certain value for the maximum principal curvature. Since the deterministic application of this simple working principle shows several problems, due to the uncertainties in the curvature estimation, a fuzzy approach is proposed. In order to segment the nodes of a tessellated model belonging to secondary features of a given radius, an appropriate set of membership functions is defined and evaluated based on some parameters, which affect the quality of the curvature estimation. A region-growing algorithm connects the nodes pertaining to a same secondary feature so that, for a given radius, one or more secondary features may be recognized. The method is applied and verified in some test cases.

Keywords: Computational geometry | Features extractions | Fuzzy logic | Mechanical engineering computing | Region growing algorithm

Abstract: In this paper, a new method for axis detection of discrete thin-walled axially symmetric surfaces is presented. This method is based on the property of thin-walled axially symmetric surfaces that the minimum path of a point on the external wall to the internal wall is on a straight line passing through the axis. This working principle, since it does not require the evaluation of differential geometrical properties, makes the method robust to noise. The proposed method has been applied in a very critical application area: axially symmetric archaeological pottery fragments, for which the evaluation of the axis is complex because of manufacturing error and of modification of the surface properties due to the action of time and weather. The trueness of the proposed method is compared with those of the five methods presented in the literature in the analysis of real sherds of various dimensions and conditions. The proposed method demonstrates greater robustness than these methods and is shown to be promising to improve the number of sherds that can be successfully analyzed.

Keywords: 3D archeology | Axis estimation | Computer | Geometric inspection | Methods in archaeology

Abstract: Despite the widespread use of reverse total shoulder arthroplasty, the fundamental effects of implant configuration on certain biomechanical outcomes have not been completely elucidated especially for the most innovative prostheses. Aim of this work is to investigate the behaviour of a new reverse shoulder prosthesis, characterized by a humeral tray with a variable offset, designed to increase the range of motion and to reduce the impingement. The purposes of this study were to evaluate the effect of reverse shoulder implant design parameters on the deltoid muscle forces, required to produce abduction, and on the shoulder range of motion, in order to provide a more systematic understanding of the fundamental effects of humeral component positioning on the implant performances. The study has been implemented using virtual prototypes of the shoulder-prosthesis assembly. The shape of the prosthesis has been digitally acquired via a 3D scanner and the CAD models of all the components have been created. Through CT images, 3-dimensional models of the shoulder bones have been reconstructed and assembled with the prosthesis components. Numerical FEM models have been set up in order to evaluate how the abduction force changes depending on the humeral tray offset. Using the virtual prototypes of the shoulder-prosthesis assembly, a range of motion analysis has been carried out by setting up a collision detection analysis in a 3D parametric modeling environment. Different humeral tray positions were investigated and four different motions of the arm were simulated. Obtained results have demonstrated that a suitable positioning of the humeral tray can offer significant biomechanical advantages in terms of range of motion and abduction force.

Keywords: CAD | FEM | Reverse engineering | Reverse shoulder prosthesis | Virtual prototyping

Abstract: In this paper we derive the analytic solutions for the statics of cantilever soft arm under external loading. The main motivation behind this work is the development of manageable and ready-to-use mathematical models of soft robotic arm for various purposes. We formulate the problem exploiting the Lie group structure of the arms' configuration space. This allows using the powerful mathematical tools from differential geometry. The model builds upon the theory of Cosserat rods: The mechanics-based perspective used to describe the kinematics and statics allows including into the model the large deformations due to axial, shear, torsion and bending effects. The position fields of the manipulators' shapes are analytically integrated and validated with respect to exact solutions and experiments.

Keywords: Cosserat rods | differential geometry | mathematical modeling | Soft robotics

Abstract: This paper presents a novel instant 3D whole body scanner for healthcare applications. It is based on photogrammetry, a digital technology which allows to reconstruct the surface of objects starting from multiple pictures. The motivation behind this work is the development of minimally invasive procedures for instant data acquisitions of anatomical structure. The scanner provides several features of interests in 3D body scanning technologies for the healthcare domains: (i) instant capture of human body models; (ii) magnitude of accuracy in the order of 1 mm; (iii) simplicity of use; (iv) possibility to scan using different settings; (v) possibility to reconstruct the texture. The system is built upon a modular and distributed architecture. In this paper we highlight its key concepts and the methodology which has led to the current product. We illustrate its potential through one of the most promising 3D scanning healthcare applications: the data acquisition and processing of human body models for the digital manufacturing process of prostheses and orthoses. We validate the overall system in terms of conformity with the the initial requirements.

Keywords: 3D reconstruction | Body scanning | Healthcare | Human body measurements | Human body visualization | Photogrammetry | Proshetics and orthotics

Abstract: Kinematic modeling of continuum robots is challenging due to the large deflections that these systems usually undergone. In this paper, we derive the kinematics of a continuum robot from the evolution of a three-dimensional curve in space. We obtain the spatial configuration of a continuum robot in terms of exponential coordinates based on Lie group theory. This kinematic framework turns out to handle robotic helical shapes, i.e. spatial configurations with constant curvature and torsion of the arm.

Keywords: Continuum robotics | Differential geometry | Kinematics

Abstract: Background and objective: The purpose of the present paper is to pave the road to the systematic optimization of complex craniofacial surgical intervention and to validate a design methodology for the virtual surgery and the fabrication of cranium vault custom plates. Recent advances in the field of medical imaging, image processing and additive manufacturing (AM) have led to new insights in several medical applications. The engineered combination of medical actions and 3D processing steps, foster the optimization of the intervention in terms of operative time and number of sessions needed. Complex craniofacial surgical intervention, such as for instance severe hypertelorism accompanied by skull holes, traditionally requires a first surgery to correctly “resize” the patient cranium and a second surgical session to implant a customized 3D printed prosthesis. Between the two surgical interventions, medical imaging needs to be carried out to aid the design the skull plate. Instead, this paper proposes a CAD/AM-based one-in-all design methodology allowing the surgeons to perform, in a single surgical intervention, both skull correction and implantation. Methods: A strategy envisaging a virtual/mock surgery on a CAD/AM model of the patient cranium so as to plan the surgery and to design the final shape of the cranium plaque is proposed. The procedure relies on patient imaging, 3D geometry reconstruction of the defective skull, virtual planning and mock surgery to determine the hypothetical anatomic 3D model and, finally, to skull plate design and 3D printing. Results: The methodology has been tested on a complex case study. Results demonstrate the feasibility of the proposed approach and a consistent reduction of time and overall cost of the surgery, not to mention the huge benefits on the patient that is subjected to a single surgical operation. Conclusions: Despite a number of AM-based methodologies have been proposed for designing cranial implants or to correct orbital hypertelorism, to the best of the authors’ knowledge, the present work is the first to simultaneously treat osteotomy and titanium cranium plaque.

Keywords: Additive manufacturing | CAD | Cranium surgery | Image processing

Abstract: Reverse Engineering (RE) is a long-term goal of engineering and computer science; it aims at the reconstruction of CAD models from measured data by means of 3D mathematical surfaces and geometrical features representing the geometry of a physical part. In the last two decades, reviews and surveys have occasionally covered this topic, but a systematic dissertation of modeling methods from a mechanical engineering point of view is still missing. The purpose of this paper is to fill this gap; starting from a general description of the overall RE framework (acquisition, segmentation, classification, fitting), both an up-to-date survey and a categorization of available modeling techniques and tools working on 3D data are provided. The main aspects of various strategies are discussed as well, in order to highlight strengths and weaknesses characterizing different approaches. Moreover, an overview of commercial software for RE is presented, considering both dedicated solutions and packages supplied as add-on with ‘traditional’ CAD systems. Finally, possible improvements to be addressed by the research in the RE field are discussed, outlining potential future trends that are still to be investigated.

Keywords: 3D modeling | CAD reconstruction | constrained fitting | Reverse engineering | reverse engineering software

Abstract: The percutaneous interventions in the treatment of structural heart diseases represent nowadays a viable option for patients at high risk for surgery. However, unlike during the traditional open heart surgery, the heart structures to be corrected are not directly visualized by the physician during the interventions. The interpretation of the available medical images is often a demanding task and needs specific skills i.e. clinical experience and complex radiological and echocardiographic analysis. The new trend for cardiovascular diagnosis, surgical planning and intervention is, today, mutually connected with most recent developments in the field of 3D acquisition, interactive modelling and rapid prototyping techniques. This is particularly true when dealing with complex heart diseases since 3D-based techniques can really help in providing an accurate planning of the intervention and to support surgical intervention. To help the research community in confronting with this new trend in medical science, the present work provides an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific cardiac structures, with particular reference to most critical phases such as: 3D image acquisition, interactive image segmentation and restoration, interactive 3D model reconstruction, physical prototyping through additive manufacturing. To this purpose, first, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of interactive image segmentation. Finally, most suitable techniques for prototyping the retrieved 3D model are investigated so as to derive a number of criteria for manufacturing prototypes useful for planning the medical intervention.

Keywords: 3D modelling | Cardiovascular diseases | Heart | Medical imagery | Rapid prototyping | Surgical planning

Abstract: With the aim of retrieving 3D surfaces starting from single shaded images, i.e. for solving the widely known shape from shading problem, an important class of methods is based on minimisation techniques where the expected surface to be retrieved is supposed to be coincident with the one that minimise a properly developed functional, consisting of several contributions. Despite several different contributes that can be explored to define a functional, the so called 'smoothness constraint' is a cornerstone since it is the most relevant contribute to guide the convergence of the minimisation process towards a more accurate solution. Unfortunately, in case input shaded image is characterised by areas where actual brightness changes rapidly, such a constraint introduces an undesired over-smoothing effect for the retrieved surface. The present work proposes an original strategy for avoiding such a typical over-smoothing effect, with regard to the image regions in which this is particularly undesired such as, for instance, zones where surface details are to be preserved in the reconstruction. The proposed strategy is tested against a set of case studies and compared with other traditional SFS-based methods to prove its effectiveness.

Keywords: 3D model | Minimisation | SFS | shape from shading | Smoothing | Smoothness constraint | variational approach

Abstract: 3D recording, digital surveying and mapping are efficient and manageable tools for reconnaissance, documentation and monitoring in underwater archaeology. Lab4Dive project, co-funded by the European Union's EMFF Programme, through the EASME and DG MARE call on 'Blue Labs', aims to design, develop and validate an innovative, marketable and competitive technology, which will assist underwater archaeologists in the field and will contribute significantly to the successful outcome of the survey process, documentation and preservation of submerged archaeological sites. In this article, the Lab4Dive system and its preliminary testing results, will be presented. The system is based on an underwater tablet coupled with an intelligent underwater case embedded with environmental sensors, a high-resolution camera and compatible with different commercial acoustic positioning systems, which will be integrated with a cloud data gathering system. During the dive, the tablet provides the diver with an augmented navigation interface, which guides him towards the selected targets. The cloud data gathering system allows the archaeologists to produce a 3D reconstruction of the site, which encompasses all the acquired information, enabling them to further study and analyze the data before the next mission.

Keywords: 3D documentation | 3D Reconstruction | IoT | Marine Robotics | Underwater Archaeology

Abstract: Images obtained in an underwater environment are often affected by colour casting and suffer from poor visibility and lack of contrast. In the literature, there are many enhancement algorithms that improve different aspects of the underwater imagery. Each paper, when presenting a new algorithm or method, usually compares the proposed technique with some alternatives present in the current state of the art. There are no studies on the reliability of benchmarking methods, as the comparisons are based on various subjective and objective metrics. This paper would pave the way towards the definition of an effective methodology for the performance evaluation of the underwater image enhancement techniques. Moreover, this work could orientate the underwater community towards choosing which method can lead to the best results for a given task in different underwater conditions. In particular, we selected five well-known methods from the state of the art and used them to enhance a dataset of images produced in various underwater sites with different conditions of depth, turbidity, and lighting. These enhanced images were evaluated by means of three different approaches: objective metrics often adopted in the related literature, a panel of experts in the underwater field, and an evaluation based on the results of 3D reconstructions.

Keywords: 3D reconstruction | Automatic colour equalization | Benchmark | CLAHE | Colour correction | Dehazing | Lab | Non-local dehazing | Screened poisson equation | Underwater image enhancement

Abstract: Within the T-VedO project, financed by Tuscany Region, the Reverse Engineering and Virtual Prototyping Lab team of the Department of Industrial Engineering of Florence (Italy) developed a number of methods for the semiautomatic generation of digital 2.5D models starting from paintings. Once such models are prototyped, they can be used to enhance visually impaired people tactile experience of artworks. Such methods, combined into a systematic procedure, allow to solve most of the typical problems arising when dealing with artistic representation of a painted scene. The present paper presents both an overview of the proposed procedure, including most recent updates, and the results obtained for a selected number of artworks of the Florentine Renaissance.

Keywords: 2.5D models | 3D Reconstruction | CAD

Abstract: Wrist injuries are one of the most common fractures, specifically around 25% of fractures among the pediatric population and up to 18% in the elderly age group are distal radius fractures. To date, the standard treatment entails the use of a tailor-made plaster of Paris cast. Although it is a simple and reliable treatment, it presents several disadvantages: its weight generally causes discomfort, it cannot be taken off without breaking it, it can cause skin rashes and prevents ventilation of the treated area. To overcome the limitations of the above mentioned treatment, 3D printed orthopaedic casts based on reverse engineering (RE) and additive manufacturing (AM) techniques have been proposed in literature. Despite these solutions prove to be a valid alternative to the standard treatment, the clinical use of AM-based devices is not trivial due to the need of expert CAD modelers to design the 3D model of the orthosis starting from the patient’s anatomy 3D acquisition. In this work, the authors identify a systematic procedure to create an orthosis model, compliant with medical guidelines, using common CAD tools. The systematic procedure, even still manually performed, envisages a set of tasks, grouped into five main blocks, that will be easy to be automatized in the future, thus eliminating the necessity of designing expertise to model the orthosis. The proposed procedure allows to design a device composed of two halves, to ease the application, locked through a zip tie-based mechanism. A preliminary ventilation pattern is proposed and tested with a FEM analysis to ensure structural resistance. The procedure has been tested on six case studies: all the orthoses models were correctly generated without major complications and positive user feedbacks were generally obtained throughout the tests.

Keywords: Cad | Cast modeling | Orthosis modelling | Personalized medicine | Reverse engineering

Abstract: This paper presents a knowledge based engineering environment methodology to support the designer in the correct setting of geometrical and dimensional tolerances in assemblies of mechanical components. The procedure is based on the definition of the functional requirements needed to allow the proper working of the assembly; in the further, a software tool is used to do a statistical analysis of the assembly relations, providing an estimation of the components waste due to poor compliance to the tolerances. A case study given by the design of a marine power transmission is presented: the methodology leads to the change of some tolerances to improve the design by reducing the number of waste components. The strength of the methodology is represented by the fact it can help unskilled designers in the correct setting of tolerances in drawings.

Keywords: CAD | CAT | design | GD&amp;T | power transmission

Abstract: Sintering shrinkage of prior cold compacted iron rings with different geometry (height to wall thickness ratio) and green density in the 6.5–7.3 g/cm3 range was investigated. It displays a minimum at an intermediate green density. Axial, tangential and radial shrinkages are different, due to the gradients of green density along the axial and the radial directions. Therefore, the effect of height on shrinkage and its anisotropy is the result of their effect on the stress distribution in the green parts during cold compaction, and the resulting green density and deformation experienced by the powder. Anisotropy decreases on increasing shrinkage.

Keywords: geometry | green density | Shrinkage anisotropy

Abstract: Considering the progressively expansive trade world, "time to market" of productions and goods has turned into a key element for business accomplishment. There are diverse practices that antedate design faults and unveil products on the market in minus time. Among the most used methods in the design and explanation of the necessities, quality function deployment (QFD) and design for Six Sigma (DFSS) can be used. In the prototyping stage, it is probable to address the emergent technology of additive manufacturing. Today, 3D printing is employed as a quick prototyping technique. Nevertheless, the tangible task which industry is fronting is the adoption of these machines for large-scale production of components, which is now possible with new HP multi fusion. The goal of this paper is to illustrate the entire product development process taking advantage of the most modern models and technologies for the final realization of a case study that involves the design and prototyping of an innovative multifunctional fan (lamp, aroma diffuser, and fan) through the multi jet fusion of HP. To begin with, issues related to the DFSS, the QFD and their application to identify the fan requirements are explored. Once the requirements have been defined, the modern CAD design systems and the CAE systems for the validation of the case study will be analyzed and applied. Finally, HP's multi jet fusion methodology and design rules for additive manufacturing will be analyzed in detail, trying to exploit all the positive aspects it offers.

Keywords: CAD | CAE | Design for additive manufacturing | Design for Six Sigma | FEA | Multi jet fusion | Product development | QFD | Rapid prototyping

Abstract: Over the last years, good strategies for efficient manufacturing were considered increasing the volume of production and reducing the time and costs. Emerging design strategies as the Design for Environment and life cycle assessment, the Design for Sustainability, the Design for Disassembly moved the focus to conceive a product by taking care of all the effect that its use can cause to the economy, to the society and to the environment, also at its disposal. In this context, design strategies have to be enhanced in order to integrate innovation with sustainability and social care. Thus, the horizon for strategic manufacturing has to pay particular attention to the effects that it could produce to the surrounding environment. This way, some manufacturing techniques that could be considered obsolete in terms of sustainability awareness, but that are not yet ready to be replaced by advanced available technologies, need a requalification in order to be collocated in the current scenario. In this paper, the open moulding technique has been discussed in order to update the current manufacturing technique to meet the emerging sustainable strategies. Through the integration of QFD and TRIZ an innovative design method have been assessed to enhance the manufacturing process by means of computer aided engineering devices. PrinterCAD is a project that aims to manage additive and subtractive techniques, applied to complex and large-scale products, by means of an open source software with an integrated module, in order to enhance the CAD, CAM and slicing for the 3D printer’s languages intercommunication.

Keywords: CAD | CAM | Hybrid manufacturing | Open source | QFD | TRIZ

Abstract: Feature-based modeling and feature recognition algorithm are state of the art technologies, mainly used to favor the integration and exchange of data between design and manufacturing phases. This paper aims to investigate the possibility to extend the use of the feature recognition as a means for the prevention of ergonomics issues during the manual assembly phase, such as Work-related Musculo-Skeletal Disorders (WMSDs). Starting from the features analysis of a 3D product model, the proposed five steps method allows preventively identifying potential ergonomics issues. The main novelty of this study is related to the correlation between design tools, product virtual representations (e.g. 3D models), assembly and ergonomics aspects. Results obtained with two case studies, a cooker hood and a tool-holder carousel, confirm the usefulness of the proposed method in helping designers to prevent potential ergonomics issues for operators involved in the assembly phase.

Keywords: Ergonomics | Feature recognition | Manual assembly | Virtual product model | Work-related Musculoskeletal Disorders

Abstract: The standard treatment for bones fractures entails the use of a tailor-made plaster cast which has several disadvantages: its weight generally causes discomfort, it cannot be taken off without breaking it, it can cause skin rashes and prevents ventilation of the treated area. Therefore, the application of traditional casts to orthopaedics patients does not represent, to date, the best option. To overcome the above-mentioned drawbacks, many strategies based on reverse engineering and additive manufacturing techniques have been proposed and proved to be a valid alternative for producing custom orthoses. Encouraged by the aforementioned results, the authors have developed a low-cost system (called Oplà), specifically dedicated to the hand-wrist-arm district of paediatric patients and capable of creating a 3D CAD model of the orthosis ready to be printed by using additive manufacturing techniques. Such a system comprises a 3D scanner, a control software and a semi-automatic CAD procedure to easily model the orthopaedic device on each patient, without the need of CAD modelling professionals. To evaluate if Oplà can be effectively used by the medical staff to design patient specific 3D printable orthoses in the clinical practice, a preliminary usability assessment has been performed. Five professional nurses from the Meyer Children’s Hospital of Florence (Italy) have been selected and trained in the use of the system. Subsequently, each of them has been asked to perform the whole process for the same patient. Effectiveness, efficiency and satisfaction have been measured in accordance to ISO 9241-11. Results proved that the Oplà system is characterized by a good usability allowing the user to easily and intuitively perform all the tasks in a reasonable time.

Keywords: CAD | Cast modelling | Reverse engineering | Usability

Abstract: The visualization and analysis of mosaics and pavements are often compromised by their large sizes, which do not enable the observer to perceive their whole arrangement or to focus on details placed in farthest areas from its boundaries. Moreover, the usual precarious state of conservation of these artefacts, often with damaged or missing areas, makes it difficult to perceive their original aesthetic value. To overcome these limitations, we propose an application of augmented reality able to support the observer in two ways: first, the application completes the missing surface of the mosaic or pavement by integrating the existent surface with a virtual reconstruction; second, it enables the analysis of the geometric pattern of the mosaic/pavement by overlaying virtual lines and geometric figures in order to explicit its geometric arrangements. The result is achieved via a custom Android application able to recognize and track the mosaic figure pattern and extra marker board, obtaining in that way a coordinate system used to render in real-time the reconstruction of the mosaic. Such rendering is overlaid to the video stream of the real scene. The application runs on a standard smartphone embedded in a Google Cardboard-compatible viewer and therefore is extremely affordable. As a case study, in order to reconstruct its aspects and to analyse its geometric pattern, we chose the roman mosaic re-found in Savignano sul Panaro (near Modena, Italy) in 2011, after 115 years from its first discovery, which is preserved less than half of its original 4.5 x 6.9 m surface.

Keywords: Augmented Reality | Cultural heritage | Geometric pattern | Photogrammetry | Real-time visualization | Roman mosaic

Abstract: This paper proposes the integration of photogrammetric reconstruction, 3D modelling and augmented reality application in order to achieve the complete visualization of a stone sculpture even if highly damaged or fragmentary. The first part of the research aims to the reconstruction of the original aspect of an incomplete sculpture, by using photogrammetry techniques based on standard resolution photos and free software in order to obtain a first model; then, we integrate this model with other 3D digital data (from other sculptures of the same period) or with 3D modelling based on historical sources and views from historians, aiming to achieve the original aspect of the sculpture. The second part of the research consists of the embedding of the obtained model in a custom application able to render in real-time the 3D reconstruction of the lion. Then, the rendering is overlaid to the video stream of the real scene and, as a result, a complete 3D digital model of the sculpture is achieved and could be visualized through a VR viewer. As a case study, we focus on a Roman stone sculpture of a male lion conserved in the Museo Estense of Modena (Italy), which lacks of its head and its four legs. The original aspect of the lion may be achieved by integrating the damaged sculpture with other photogrammetric reconstructions of lions sculptures of the same period and with 3D model based on historical sources. Finally, the lion is visualized through an augmented reality application which digitally overlays the reconstructed models on the original one.

Keywords: Augmented Reality | Cultural heritage | Photogrammetry | Real-time visualization | Virtual modeling

Abstract: This paper deals with a numerical investigation, based on the Finite Element (FE) theory, of a Structural Health Monitoring (SHM) system for a large radio-telescope, aimed to damage detection and location. The investigated SHM system is based on the comparison of the Frequency Response Functions (FRFs) achieved under both pristine and damaged configurations, respectively. A preliminary study has been carried out in order to achieve information on the optimal sensors locations. As a result, the structural response of the radio-telescope under the in-service loading conditions has been numerically investigated. All FE analyses have been carried out by means of MD Nastran® code.

Keywords: Damage | FE Analysis | Modelling | Radio-Telescope | SHM

Abstract: Manual Material Handling (MMH), by pushing or pulling carts, is a common task that characterizes any manufacturing or service operation, and there is always a significant human input to those operations in terms of physical load. The physical load represents the effect of input forces during MMH operations that depend on the interaction between material handling equipment and the working environment. Many times MMH represents a critical issue related to human-machine interaction due to the carts can work in environment with parameters different from those used in designing, subjecting workers to risk of musculoskeletal disorders. The aim of this work, developed in collaboration with Fiat Chrysler Automobiles (FCA), is to develop a new procedure that allows estimating the initial and the maintenance forces necessary to push or pull carts, knowing the characteristics of the cart and the environment in which it works, in order to preventively assess the ergonomic indexes according to ISO 11228-2. The procedure is based on multibody simulations. The cart is modeled by Computer Aided Design (CAD) code and, then, imported in a multibody code where numerical simulations are performed in order to calculate the forces. In the multibody code static and dynamic friction coefficients of bearing of wheels are assigned, together with parameters of contact between wheels and floor. Changing the pivot angle of two floating wheels, several simulations have been carried out. Moreover, considering a cart used at the assembly line of the FCA plant of Pomigliano d'Arco (Naples), experimental tests have been performed in order to validate the procedure by comparing numerical results with the experimental ones.

Keywords: Ergonomics | Material Manual Handling | Multibody | Pushing/Pulling actions

Abstract: In this paper, a new methodology supporting the design of landing gears is proposed. Generally, a preliminary step is performed with simplified FE model, usually one-dimensional, to achieve the reaction forces involving each component during all aforementioned aircraft operations. Though this approach gives a valid support to the designer, it is characterized by several problems, such as the related approximations. So, it is important, by a numerical point of view, to develop an isostatic FE model equivalent to the real one. In fact, if the landing gear is modelled as hyperstatic, the static equilibrium equations are insufficient for determining the internal forces and reactions on each sub-component; so, the modelled material properties and geometries assume an increasing importance, which gets the model too approximating. The proposed methodology consists of achieving the reaction forces by means of multibody simulations, by overcoming such problems, since each component is modelled as rigid. In this paper, also a FE model for the investigation of the structural response is proposed. Aimed to Certification by Analysis purposes, the developed multibody and the FE models have been assessed against an experimental landing gear drop test carried out by Magnaghi Aeronautica S.p.A., according to the EASA CS 25 regulations.

Keywords: Drop test | Dynamic behaviour | FE analysis | Landing gear | Multibody

Abstract: This study proposes a novel automatic method for facial landmark localization relying on geometrical properties of 3D facial surface working both on complete faces displaying different emotions and in presence of occlusions. In particular, 12 descriptors coming from Differential Geometry including the coefficients of the fundamental forms, Gaussian, mean, principal curvatures, shape index and curvedness are extracted as facial features and their local geometric properties are exploited to localize 13 soft-tissue landmarks from eye and nose areas. The method is deterministic and is backboned by a thresholding technique designed by studying the behaviour of each geometrical descriptor in correspondence to the locus of each landmark. Occlusions are managed by a detection algorithm based on geometrical properties which allows to proceed with the landmark localization avoiding the covered areas. Experimentations were carried out on 3132 faces of the Bosphorus database and of a 230-sized internal database, including expressive and occluded ones (mouth, eye, and eyeglasses occlusions), obtaining 4.75 mm mean localization error.

Keywords: 3D face | Differential geometry | Face analysis | Feature extraction | Landmark localization

Abstract: Collaborative robots must operate safely and efficiently in ever-changing unstructured environments, grasping and manipulating many different objects. Artificial vision has proved to be collaborative robots’ ideal sensing technology and it is widely used for identifying the objects to manipulate and for detecting their optimal grasping. One of the main drawbacks of state of the art robotic vision systems is the long training needed for teaching the identification and optimal grasps of each object, which leads to a strong reduction of the robot productivity and overall operating flexibility. To overcome such limit, we propose an engineering method, based on deep learning techniques, for the detection of the robotic grasps of unknown objects in an unstructured environment, which should enable collaborative robots to autonomously generate grasping strategies without the need of training and programming. A novel loss function for the training of the grasp prediction network has been developed and proved to work well also with low resolution 2-D images, then allowing the use of a single, smaller and low cost camera, that can be better integrated in robotic end-effectors. Despite the availability of less information (resolution and depth) a 75% of accuracy has been achieved on the Cornell data set and it is shown that our implementation of the loss function does not suffer of the common problems reported in literature. The system has been implemented using the ROS framework and tested on a Baxter collaborative robot.

Keywords: Collaborative robotics | Deep learning | Engineering methods | Vision-guided robotic grasping

Abstract: Objectives To investigate the influence of specific resin-composite, glass ceramic and glass ionomer cement (GIC) material combinations in a “multi-layer” technique to replace enamel and dentin in class II mesio-occlusal-distal (MOD) dental restorations using 3D-Finite Element Analysis (FEA). Methods Four 3D-FE models (A–D) of teeth, adhesively restored with different filling materials, were created and analyzed in comparison with a 3D model (E) of a sound lower molar. Models A, B & C had “multilayer” constructions, consisting of three layers: adhesive, dentin replacement and enamel replacement. Model A: had a low modulus (8 GPa) composite replacing dentin and a higher modulus (12 GPa) composite replacing enamel. Model B: had a GI cement replacing dentin and a higher modulus (12 GPa) composite replacing enamel. Model C: had a low modulus (8 GPa) composite replacing dentin and a very high modulus (70 GPa) inlay replacing enamel. Model D: had a lithium disilicate inlay replacing both dentin and enamel with a luting cement base-layer. Polymerization shrinkage effects were simulated and a load of 600 N was applied. All the materials were assumed to behave elastically throughout the entire deformation. Results Model A showed the highest stress distribution along all the adhesive interfaces of the shrinking resin-based materials with a critical condition and failure risk marginally and internally. Model D, by contrast, showed a more favorable performance than either of the multilayer groups (A–C). Stress and displacement plots showed an elastic response similar to that obtained for the sound tooth model. Model B and Model C performed according to their bilayer material properties. The use of a non-shrink dentin component simulating a GIC clearly affected the shrinkage stress at the basis of the Model B; while the bulk resin composite having a 12 GPa Young's modulus and linear polymerization shrinkage of 1% strongly influenced the biomechanical response in the bucco-lingual direction. Significance Direct resin-based composite materials applied in multilayer techniques to large class II cavities, with or without shrinking dentin layers, produced adverse FEA stress distributions and displacements. An indirect lithium disilicate inlay used to replace lost dentin and enamel in posterior restored teeth generated lower stress levels, within the limits of the elastic FEA model.

Keywords: CAD | Class II restorations | Finite element analysis | Image analysis | Materials properties

Abstract: Objective To assess the effect of a ferrule design with specific post material-shape combinations on the mechanical behavior of post-restored canine teeth. Methods Micro-CT scan images of an intact canine were used to create a 3-D tessellated CAD model, from which the shapes of dentin, pulp and enamel were obtained and geometric models of post-endodontically restored teeth were created. Two types of 15 mm post were evaluated: a quartz fiber post with conical–tapered shape, and a carbon (C) fiber post with conical–cylindrical shape. The abutment was created around the coronal portion of the posts and 0.1 mm cement was added between prepared crown and abutment. Cement was also added between the post and root canal and a 0.25 mm periodontal ligament was modeled around the root. Four models were analysed by Finite Element (FE) Analysis: with/without a ferrule for both types of post material and shape. A load of 50 N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum normal stress criterion was adopted as a measure of potential damage. Results Models without a ferrule showed greater stresses (16.3 MPa) than those for models with a ferrule (9.2 MPa). With a ferrule, stress was uniformly distributed along the abutment and the root, with no critical stress concentration. In all models, the highest stresses were in the palatal wall of the root. Models with the C-fiber post had higher stress than models with the quartz fiber posts. The most uniform stress distribution was with the combination of ferrule and quartz fiber post. Significance The FE analysis confirmed a beneficial ferrule effect with the combination of ferrule and quartz fiber post, with tapered shape, affording no critical stress concentrations within the restored system.

Keywords: CAD | Dental materials | Endodontic treatment | Finite element analysis | Image analysis | Materials properties

Abstract: Objectives To study the influence of resin based and lithium disilicate materials on the stress and strain distributions in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). To investigate the materials combinations in the restored teeth during mastication and their ability to relieve stresses. Methods One 3D model of a sound lower molar and three 3D class II MOD cavity models with 95° cavity-margin-angle shapes were modelled. Different material combinations were simulated: model A, with a 10 μm thick resin bonding layer and a resin composite bulk filling material; model B, with a 70 μm resin cement with an indirect CAD-CAM resin composite inlay; model C, with a 70 μm thick resin cement with an indirect lithium disilicate machinable inlay. To simulate polymerization shrinkage effects in the adhesive layers and bulk fill composite, the thermal expansion approach was used. Shell elements were employed for representing the adhesive layers. 3D solid CTETRA elements with four grid points were employed for modelling the food bolus and tooth. Slide-type contact elements were used between the tooth surface and food. A vertical occlusal load of 600 N was applied, and nodal displacements on the bottom cutting surfaces were constrained in all directions. All the materials were assumed to be isotropic and elastic and a static linear analysis was performed. Results Displacements were different in models A, B and C. Polymerization shrinkage hardly affected model A and mastication only partially affected mechanical behavior. Shrinkage stress peaks were mainly located marginally along the enamel-restoration interface at occlusal and mesio-distal sites. However, at the internal dentinal walls, stress distributions were critical with the highest maximum stresses concentrated in the proximal boxes. In models B and C, shrinkage stress was only produced by the 70 μm thick resin layer, but the magnitudes depended on the Young's modulus (E) of the inlay materials. Model B mastication behavior (with E = 20 GPa) was similar to the sound tooth stress relief pattern. Model B internally showed differences from the sound tooth model but reduced maximum stresses than model A and partially than model C. Model C (with E = 70 GPa) behaved similarly to model B with well redistributed stresses at the occlusal margins and the lateral sides with higher stress concentrations in the proximal boxes. Models B and C showed a more favorable performance than model A with elastic biomechanics similar to the sound tooth model. Significance Bulk filling resin composite with 1% linear polymerization shrinkage negatively affected the mechanical behavior of class II MOD restored teeth. Class II MOD direct resin composite showed greater potential for damage because of higher internal and marginal stress evolution during resin polymerization shrinkage. With a large class II MOD cavity an indirect composite or a lithium disilicate inlay restoration may provide a mechanical response close to that of a sound tooth.

Keywords: CAD | Composite | FEA | Inlay | Lithium Disilicate | Micro-CT | Stress analysis

Abstract: Objective To study the influence of the different class II mesio-occlusal-distal (MOD) cavity shape on the stress and strain distributions in adhesive indirect restorations, using numerical finite element analysis (FEA). To investigate the relationship between restored teeth failure and stiffness of food, three values of Young's modulus were used for the food. Methods A 3D model of a sound lower molar and three class II MOD cavities with different shape were created. Slide-type contact elements were used between tooth surface and food. An adhesive resin-based cement, modeled with fixed-type contact elements, and a single restorative filling materials were considered. To simulate polymerization shrinkage effect, which is basically restricted to the thin composite cement layer, shell elements were employed and the thermal expansion approach was used. A vertical occlusal load of 600 N was applied, while assigning fixed zero-displacements on the cutting surfaces below the crevices. All the materials were assumed to be isotropic and elastic. A static linear analysis was carried out. Results In the lingual cusp, the displacements increased as the values of the stiffness food increased. In the restored teeth, the stress near the restoration-tooth interface was strongly dependent on the MOD cavity shape. The stress peaks were mainly located along the enamel–dentin interface at the lingual side; wedge-shaped MOD cavity with a low angle, in combination with the lowest food stiffness provided the best results. Significance A more complex load application on the occlusal surfaces was introduced. Food stiffness slightly affected the stress distribution of the restored and sound teeth. Teeth with adhesive class II MOD indirect resin composite restorations were potentially more susceptible to damage if the class II MOD cavity-margin-angle was higher than 95°. Restored teeth with a higher cavity-margin-angle led to considerable stress concentration in the lingual cusp along the enamel–dentin interface. These models were more susceptible to fracture in the lingual cusps when compared to the buccal ones.

Keywords: CAD | Endodontics | Finite element analysis | Micro-computed tomography | Stress analysis

Abstract: A new method for secondary features segmentation, performed in highdensity acquired geometric models, is proposed. Four types of secondary features are considered: fillets, rounds, grooves and sharp edges. The method is based on an algorithm that analyzes the principal curvatures. The nodes, potentially attributable to a fillet of given geometry, are those with a certain value for maximum principal curvature. Since the deterministic application of this simple wor king principle shows several problems due to the uncertainties in the curvature estimation, a fuzzy approach is proposed. In order to segment the nodes of a tessellated model that pertain to the same secondary features, proper membership functions are evaluated as function of some parameters, which affect the quality of the curvature estimation. A region growing algorithm connects the nodes pertaining to the same secondary feature. The method is applied and verified for some test cases.

Keywords: Computational geometry | Features extractions | Fuzzy logic | Mechanical engineering computing | Region growing algorithm

Abstract: The present paper deals with methods for product development aimed to support designing activities and to re-use company know-how. The work is addressed to complex products i.e. products characterized by several components and dependencies among them. Then, the paper presents both the methodological approach and the application to the 3D CAD modelling of an automotive car door assembly. The work uses directed graphs and a series of algorithms to provide a Graphical User Interface (GUI) able to support a designer by reducing the development time of new car door assemblies and increasing the accuracy of the design activities. According to a digital pattern approach, the GUI is used to determine the set of changes to 3D CAD models that typically occur in the automotive field, during the development of new car door assemblies.

Keywords: Automotive car door design and development | CAD modelling | Digital pattern for product development | Directed graphs

Abstract: Aim of this work is to investigate the behaviour of a new reverse shoulder prosthesis, characterized by a humeral metaphysis with a variable offset, designed to increase the range of movements and to reduce the impingement. In particular, by means of virtual prototypes of the prosthesis, different offset values of the humeral metaphysis have been analysed in order to find the best positioning able to maximize the range of movements of the shoulder joint. The abduction force of the deltoid, at different offset values, has been also estimated. The study has been organized as follows. In the first step, the point clouds of the surfaces of the different components of the prosthesis have been acquired by a 3D scanner. This kind of scanner allows to convert camera images into three-dimensional models by analysing the moiré fringes. In the second step, the acquired point clouds have been post-processed and converted into CAD models. In the third step, all the 3D reconstructed models have been imported and assembled through a CAD system. After, a collision analysis has been performed to detect the maximum angular positions of the arm at different metaphysis offset values. In the last step, FEM models of shoulder joint with the new prosthesis have been created. Different analyses have been performed to estimate how the deltoid abduction force varies depending on the offset of the humeral tray. The study allowed to understand how the offset of the metaphysis affects the performances of the shoulder. The obtained results can be effectively used to give surgeons useful guidelines for the installation of these kinds of implants.

Keywords: CAD | Range of movements | Reverse engineering | Reverse shoulder prosthesis

Abstract: This paper presents a nonlinear finite element formalism for modelling the dynamics of flexible manipulators using the special Euclidean group SE(3) framework. The method is based on a local description of the motion variables, and results in a singularity-free formulation which exhibits important advantages regarding numerical implementation. The motivation behind this work is the development of a new class of model-based control systems which may predict and thus avoid the deformations of a real flexible mechanism. Finite element methods based on the geometrically exact beam theory have been proven to be the most accurate to account for flexibility: in this paper we highlight the key aspects of this formulation deriving the equations of motion of a flexible constrained manipulator and we illustrate its potential in robotics through a simple case study, the dynamic analysis of a two-link manipulator, simulating different model assumptions in order to emphasize its real physical behavior as flexible mechanism.

Keywords: differential geometry | Flexible manipulators | motion formalism | nonlinear finite element | robot simulation | soft robots

Abstract: The current trend in manufacturing is to obtain a flexible work cell in which human and robot can safely interact and collaborate. Virtual Reality (VR) represents an effective tool capable of simulating such complex systems with a high level of immersion. In order to take advantage of VR technologies to study Human-Robot Cooperation (HRC), a digital model of a redundant manipulator (KUKA LBR iiwa) has been developed starting with kinematic modeling and then coupled with the real robot. This approach allows simulating HRC in several scenarios, to reproduce the safe behavior on the real robot, as well as to train operators.

Keywords: Human-robot collaboration | Modelling | Simulation | Virtual reality

Abstract: Transparent and removable aligners represent an effective solution to correct various orthodontic malocclusions through minimally invasive procedures. An aligner-based treatment requires patients to sequentially wear dentition-mating shells obtained by thermoforming polymeric disks on reference dental models. An aligner is shaped introducing a geometrical mismatch with respect to the actual tooth positions to induce a loading system, which moves the target teeth toward the correct positions. The common practice is based on selecting the aligner features (material, thickness, and auxiliary elements) by only considering clinician's subjective assessments. In this article, a computational design and engineering methodology has been developed to reconstruct anatomical tissues, to model parametric aligner shapes, to simulate orthodontic movements, and to enhance the aligner design. The proposed approach integrates computer-aided technologies, from tomographic imaging to optical scanning, from parametric modeling to finite element analyses, within a 3-dimensional digital framework. The anatomical modeling provides anatomies, including teeth (roots and crowns), jaw bones, and periodontal ligaments, which are the references for the down streaming parametric aligner shaping. The biomechanical interactions between anatomical models and aligner geometries are virtually reproduced using a finite element analysis software. The methodology allows numerical simulations of patient-specific conditions and the comparative analyses of different aligner configurations. In this article, the digital framework has been used to study the influence of various auxiliary elements on the loading system delivered to a maxillary and a mandibular central incisor during an orthodontic tipping movement. Numerical simulations have shown a high dependency of the orthodontic tooth movement on the auxiliary element configuration, which should then be accurately selected to maximize the aligner's effectiveness.

Keywords: Computational engineering | Computer-aided design | Finite element analysis | Orthodontic treatment | Patient-specific modeling | Polymeric aligner

Abstract: The demand of new tools devoted to integrate aesthetic design into classic parametric CAD suites has undergone a raising interest from the user community. Industrial tools for reconstructing the 3D geometry of an object starting from 2D representations and for surfacing wireframe models according to designers intent, assumed a high relevance and have experienced a steady evolution. The problem of surfacing wireframe models with consistent closing surface patches is still a hot topic in the computer graphics as well as in the industrial field, as demonstrated by a number of recent works. In this paper, authors propose a procedure for enhancing the surfacing process by using shading information, together with the wireframe model. In particular, this work allows to use shading, represented either in a rendered 3D model or sketched by a designer, for retrieving consistent geometrical information related to the 3D object. The procedure is accompanied by some selected case studies, to highlight its strengths and weaknesses.

Keywords: 3D reconstruction | CAD | Hand-drawn sketches | Surfacing | Wireframe model

Abstract: Cardiovascular diagnosis, surgical planning and intervention are among the most interested in recent developments in the field of 3D acquisition, modelling and rapid prototyping techniques. In case of complex heart disease, to provide an accurate planning of the intervention and to support surgical planning and intervention, an increasing number of Hospitals make use of physical 3D models of the cardiac structure, including heart, obtained using additive manufacturing starting from the 3D model retrieved with medical imagery. The present work aims in providing an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific heart and cardiac structures, with particular reference to most critical phases such as segmentation and aspects concerning converting digital models into physical replicas through rapid prototyping techniques. First, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of semi-automatic image segmentation. Then, most suitable techniques for prototyping the retrieved 3D model are investigated so as to draft some hints for creating prototypes useful for planning the medical intervention.

Keywords: 3D modelling | 3D printing | Cardiovascular diseases | Heart | Medical imagery | Rapid prototyping | Surgical planning

Abstract: This work presents Reverse Engineering and Computer Aided technologies to improve the inspection of injection moulded electro-mechanical parts. Through a strong integration and automation of these methods, tolerance analysis, acquisition tool-path optimization and data management are performed. The core of the procedure concerns the automation of the data measure originally developed through voxel-based segmentation. This paper discusses the overall framework and its integration made according to Smart Manufacturing requirements. The experimental set-up, now in operative conditions at ABB SACE, is composed of a laser scanner installed on a CMM machine able to measure components with lengths in the range of 5÷250 mm, (b) a tool path optimization procedure and (c) a data management both developed as CAD-based applications.

Keywords: Computer Aided Tolerancing &amp; Inspection | Feature Recognition | Injection Moulding | Path Planning | Product Data Management | Quality Inspection | Reverse Engineering | Segmentation

Abstract: Nowadays, the most updated CAE systems include structural optimization toolbox. This demonstrates that topological optimization is a mature technique, although it is not a well-established design practice. It can be applied to increase performance in lightweight design, but also to explore new topological arrangements. It is done through a proper definition of the problem domain, which means defining functional surfaces (interface surfaces with specific contact conditions), preliminary external lengths and geometrical conditions related to possible manufacturing constraints. In this sense, its applicability is possible for all kind of manufacturing, although, in Additive Manufacturing, its extreme solutions can be obtained. In this paper, we aim to present the general applicability of topological optimization in the design workflow together with a case study, exploited according to two design intents: the lightweight criterion and the conceptual definition of an enhanced topology. It demonstrates that this method may help to decrease the design efforts, which, especially in the case of additive manufacturing, can be reallocated for other kind of product optimization.

Keywords: Additive Manufacturing | Conceptual Design | Design Intent | Lightweight Design | Topological Optimization

Abstract: This work describes a simple, fast, and robust method for identifying, checking and managing the overlapping image keypoints for 3D reconstruction of large objects with numerous geometric singularities and multiple features at different lighting levels. In particular a precision 3D reconstruction of an extensive architecture captured by aerial digital photogrammetry using Unmanned Aerial Vehicles (UAV) is developed. The method was experimentally applied to survey and reconstruct the 'Saraceni' Bridge' at Adrano (Sicily), a valuable example of Roman architecture in brick of historical/cultural interest. The variety of features and different lighting levels required robust self-correlation techniques which would recognise features sometimes even smaller than a pixel in the digital images so as to automatically identify the keypoints necessary for image overlapping and 3D reconstruction. Feature Based Matching (FBM) was used for the low lighting areas like the intrados and the inner arch surfaces, and Area Based Matching (ABM) was used in conjunction to capture the sides and upper surfaces of the bridge. Applying SIFT (Scale Invariant Feature Transform) algorithm during capture helped find distinct features invariant to position, scale and rotation as well as robust for the affinity transformations (changes in scale, rotation, size and position) and lighting variations which are particularly effective in image overlapping. Errors were compared with surveys by total station theodolites, GPS and laser systems. The method can facilitate reconstruction of the most difficult to access parts like the arch intrados and the bridge cavities with high correlation indices.

Keywords: Architectural reconstruction | Area Based Matching | Feature Based Matching | Photogrammetry | SIFT algorithm

Abstract: The participation of blind people (BP) in cultural life can be improved by enhancing methodologies and tools for facilitating the 3D reproduction of artworks and, at the same time, to facilitate their exploration. The creation of integrated systems including not only tactile media such as, for instance, sculptures or bas-reliefs but even a set of tools capable of providing the users with an experience cognitively comparable to the one originally envisioned by the artist, may undoubtedly enhance artworks exploration. The present work aims to design a conceptual system to aid BP in the tactile exploration of bas-reliefs. This conceptual system comprises both a hand-tracking system and an audio device, together with a number of methodologies, algorithms and information related to physical design. The designed layout, preliminarily tested to understand its potential and limits, proved to be a promising first attempt in enhancing the BP exploration experience.

Keywords: 3D reconstruction | Blind people | Hand-tracking system | Tactile bas-relief | Tactile exploration

Abstract: This paper describes the features of AMCOMP, a CAD environment conceived to manage the computation of the Added Masses of bodies moving in an infinite fluid. A methodology already published in literature has been implemented in a CAD environment and its features are exploited to perform the evaluation of the Added Masses. These include the importing of the model in STL file format and the computation of the complete Added Mass matrix and non-dimensional terms. The CAD has been validated by computing the Added Masses values of bodies whose exact formulation was found in literature. The validated tool has been applied to more complex case studies where the Added Masses values were guessed using empirical laws or the equivalent ellipsoid approximation. Significant differences have been found between approximated methods and computations on real shapes. It is shown that the precision in the Added Masses computation and the computational time depend on the meshing quality of the model and power of the PC on which the software runs. Several tools have been merged to obtain a model useful for the Added Masses computation and to assess the errors arising from using approximated formulas instead of the real shape of the body.

Keywords: Added Masses | Computer Aided Design | Conceptual design | User interface

Abstract: The mounting attention to environmental issues requires adopting better disassembly procedures at the product's End of Life. Planning and reckoning different disassembly strategies in the early stage of the design process can improve the development of sustainable products with an easy dismissing and recycling oriented approach. Nowadays many Computer Aided Process Planning software packages provide optimized assembly or disassembly sequences, but they are mainly based on a time and cost compression approach, neglecting the human factor. The environment we developed is based upon the integration of a CAD, an Augmented Reality tool, a Leap Motion Controller device, see-through glasses and an algorithm for disassembly strategies evaluation: this approach guarantees a more effective interaction with the 3D real and virtual assembly than an approach relying only on a CAD based disassembly sequence planning. In such a way, the operator may not test in a more natural and intuitive way automatic disassembly sequences, but he/she can also propose different strategies to improve the ergonomics. The methodology has been tested in a real case study to evaluate the strength points and criticalities of this approach.

Keywords: Augmented Reality | CAD | Design for Disassembly | Disassembly Sequence Optimization

Abstract: This paper presents the development of a CAD conceived to support the modelling of lightweight and lattice structures just from the initial stages of the design process. A new environment, called LWSM (acronym of LightWeight Structures Modelling), has been implemented in Python programming language in an open-source CAD software to allow the fast modelling of several sandwich structures or the filling of solid parts with cubic and tetrahedral lattice structures which can be produced by Additive Manufacturing (AM) techniques. Several tests have been carried out to validate the tool, one of which is included in the paper. The design of a bracket component inside LWSM using a traditional dense geometry and a lattice structure is described. The use of Design for Additive Manufacturing (DfAM) functions helps the user in the design of innovative structures which can produced only with AM technologies. A significant change in the shape of the part respect to traditional solutions is noticed after the use of DfAM functions by experimenters: FEM analysis confirms a strong weight reduction.

Keywords: Additive manufacturing | CAD | FEM analysis | Lattice structure | Lightweight structures

Abstract: Sintering shrinkage of uniaxially cold compacted axi-symmetrical parts is anisotropic. Not only is the shrinkage of height (parallel to the compaction direction) different from that of the diameters (in the compaction plane), but even the dimensional changes of the inner and of the outer diameters differ significantly. This behaviour has been investigated on iron rings with different geometry and green density. In the compaction plane radial and tangential shrinkages are different, and tangential shrinkage significantly changes along the wall thickness. This is due to the distribution of radial and tangential stresses during cold compaction that in turn depends on the axial stress. The stress field and its dependence on both green density and geometry were hypothesized to propose a working direction to interpret the anisotropy of sintering shrinkage in real parts.

Keywords: Geometry | Green density | Sintering shrinkage

Abstract: A feasibility study was performed in order to demonstrate the benefits of designing and manufacturing a customized foot orthosis by means of digital technologies, such as Reverse Engineering (RE), Generative Design (GD) and Additive Manufacturing (AM). The aim of this work was to define the complete design-manufacturing process, starting from the 3D scanning of the human foot anatomy to the direct fabricating of the customized foot orthosis. Moreover, this first methodological study tries to combine a user-friendly semi-automatic modelling approach with the use of low-cost devices for the 3D laser scanning and the 3D printing processes. Finally, the result of this approach, based on digital technologies, was also compared with that achieved by means of conventional manual techniques.

Keywords: Additive manufacturing | Computer aided design | Foot orthosis | Generative design | Reverse engineering

Abstract: We present the stress analysis of a pouring concrete device. In order to test the prototype of a pouring concrete equipment composed of fivearms with hollow rectangular cross sections, an extensive study about equipment for pouring concrete has been undertaken. An upgrade of a four-arms device already existing and actually working would be developed. Tests have been performed both on the prototype of the equipment and on a virtual model of the device, performed by a 3D CAD modeler and analyzed through FEM numerical programs. During experimental tests, a laser device has measured deflections at the end of the fifth arm, corresponding to applied loads. For measuring strains in the critical points highlighted by the numerical simulation strain rosette have been employed. In both the static and the dynamic conditions, Mohr's circles have been drawn from the 3D strain state and the 2D plane stress experimental records and they have been compared with those predicted through the finite element analysis. From the comparison between numerical and experimental results, a very good correlation has been obtained for static loading to assess the soundness of the virtual model.

Keywords: Articulated device | CAD | FEM | Mohr's circle | Strain analysis

Abstract: Hybrid Manufacturing (HM) is oriented to combine the advantages of additive manufacturing, such as few limits in shape reproduction, good customization of parts, distributive production, minimization of production costs and minimization of waste materials, with the advantages of subtractive manufacturing, in terms of finishing properties and accuracy of dimensional tolerances. In this context, our research group presents a design technique that aims to data processing that switches between additive and subtractive procedures, to the costs and time of product-manufacturing optimization. The component prototyping may be performed combining different stages (addiction, gross milling, fine milling, deposition…) with different parameters and head/nozzles and is able to work with different materials either in addictive, either in milling. The present paper is dedicated to introduce different strategies, or in other terms, different combinations of machining features (addictive or deductive) and different materials to complete a prototype model or mold. The optimization/analys ispiece of software is fully integrated in classic CAD/CAM environment for better supporting the design and engineering processes.

Keywords: CAD | CAM | Hybrid manufacturing | Multimaterial manufacturing | Process design

Abstract: During manufacturing, porcelain whiteware changes its shape due to the sintering process. For this reason, leader companies in the field of ceramics apply strict controls on final products in order to reach high quality standards. Typically, three quality parameters are considered: drop of the bottom, bending of the rim and roundness. To date, the assessment of such parameters is still based on visual inspections and manual measurements. In the present paper, authors propose a new quality assessment procedure based on reverse engineering (RE), able to measure the most relevant quality parameters in an effective, reliable and repeatable way.

Keywords: 3D model | 3D reconstruction | 3D scanning | measurement | porcelain | porcelain tableware | quality control | quality parameters | reverse engineering | whiteware

Abstract: Body scanning presents unique value in delivering the first digital asset of a human body thus resulting a fundamental device for a range of applications dealing with health, fashion and fitness. Despite several body scanners are in the market, recently depth cameras such as Microsoft Kinect® have attracted the 3D community; compared with conventional 3D scanning systems, these sensors are able to capture depth and RGB data at video rate and even if quality and depth resolution are not optimal for this kind of applications, the major benefit comes from the overall acquisition speed and from the IR pattern that allows poor lighting conditions optimal acquisition. When dealing with non-rigid bodies, unfortunately, the use of a single depth camera may lead to inconsistent results mainly caused by wrong surfaces registration. With the aim of improving existing systems based on low-resolution depth cameras, the present paper describes a novel scanning system for capturing 3D full human body models by using multiple Kinect® devices in a compact setup. The system consists of an instantaneous scanning system using eight depth cameras, appropriately arranged in a compact wireframe. To validate the effectiveness of the proposed architecture, a comparison of the obtained 3D body model with the one obtained using a professional Konica Minolta Range Seven 3D scanner is also presented and possible drawbacks are hinted at.

Keywords: 3D modelling | Body scanning | Custom Avatar | Depth Camera | Model Fitting

Abstract: Modular product design is an efficient strategy to let manufacturing companies meet the customers' requirements by offering a wide variety and customization of products and significantly saving time and cost during engineering and production (Fei et al., 2011). Despite numerous approaches for function modeling and modular product design (Srinivasan et al., 2012; Eckert, 2013; Vermaas, 2013) that have been developed in the last decades, carrying out an efficient product variants' design process is still an open issue for many manufacturing companies. The proposed approaches offer numerous ways to model information about product functionality, but each approach is useful and particularly well suited for different applications and domains (Summers et al., 2013). The present research compares the existing approaches for product variants design and defines a function-based model to support product design and redesign according to a modular framework, merging qualitative technical issues with business-oriented evaluation. Such a framework has been used to develop a multiuser IT platform, composed of a knowledge-based engine and four different tools to support designers and engineers in product variants creation, management, and configuration, from product functional modeling to cost estimation and life cycle assessment. The proposed model has been tested on industrial cases in the context of household appliances. Experimental results demonstrates that, after a preliminary context analysis and a proper knowledge base creation, such a model supports a more conscious decision-making and promote collaboration within an interdisciplinary design team. Finally, the case study shows the necessity, but in the meanwhile the insufficiency, of a functional decomposition as the only representation viewpoint.

Keywords: Computer-Aided Design | Design Methods | Function Modeling | Product Family and Platform | Product Modeling

Abstract: Cost estimation is a critical issue for many companies concerning both offers generation and company strategic evaluations. In this paper, a framework for early cost estimation has been proposed to some firms for an assessment of its main features. The aim of the industrial survey is to promote a discussion on the needs and the expectations regarding cost estimation in order to obtain feedbacks to be addresses in the implementation of a software tool. Gather data has led to a ranking of the main characteristics the tool should have.

Keywords: CAD | Design to Cost | Early cost estimation | Knowledge-based engineering | PLM | Product configuration

Abstract: Shape from shading (SFS) denotes the problem of reconstructing a 3D surface, starting from a single shaded image which represents the surface itself. Minimization techniques are commonly used for solving the SFS problem, where the objective function is a weighted combination of the brightness error, plus one or more terms aiming to obtain a valid solution. We present a regularized quadratic penalty method where quadratic penalization is used to adaptively adjust the smoothing weights, and regularization improves the robustness and reliability of the procedure. A nonmonotone Barzilai–Borwein method is employed to efficiently solve the arising subproblems. Numerical results are provided showing the reliability of the proposed approach.

Keywords: Barzilai–Borwein method | quadratic penalty methods | quadratic regularization | Shape from shading

Abstract: An engineering design process consists of a sequence of creative, innovative and routine design tasks. Routine tasks address well-known procedures and add limited value to the technical improvement of a product, even if they may require a lot of work. In order to focus designers work on added value tasks, the present work aims at supporting a routine task with a Design Archetype (DA). A DA captures, stores and reuses the design knowledge with a tool embedded in a CAD software. The DA algorithms drive the designer in selecting the most effective design concept to deliver the project requirements and then embody the concept through configuring a CAD model. Finally, a case study on the definition of a DA tool for gear design demonstrates the effectiveness of the DA tool.

Keywords: Computer Aided Design | Design Archetype | Design automation | Design knowledge | Engineering design

Abstract: Sustainability is becoming one of the main drivers of the modern product and system design. However, sustainability assessments are usually carried out at the end of the design process to check the validity of the decisions already taken. As a consequence, when targets are not achieved, numerous time-consuming iteration loops are necessary to optimize the initial solution. The paper merges functional-based and design-to-cost approaches to propose a CAD-based platform able to assess product lifecycle costs and impacts from the earliest design stages by configuring and assessing feasible design solutions. It considers both economic expenses and environmental impacts during all phases of product lifecycle on the basis of the company knowledge.

Keywords: CAD | Design-to-cost | functional design | lifecycle approach | sustainability

Abstract: 3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies of Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 105 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms, and by applying standard functions such as sine, cosine, and logarithm to them. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that some newly generated descriptors were sounder than the primary ones, meaning that their local behaviours in correspondence to a landmark position is thoroughly specific and can be registered with high similarity on every face of our dataset.

Keywords: 3D face | Face analysis | Face expression recognition | Face recognition | Geometry | Landmarks

Abstract: 3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies in Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 54 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that the newly generated descriptors are suitable to 3D face description and to support landmark localization procedures.

Keywords: 3D Face | Face Analysis | Face Recognition | Geometry | Landmarks

Abstract: Material behavior depends on average peak temperature, stress magnitude and stress gradient. This assumption is valid since temperatures varies slowly when compared to pressure (stress). In this paper, a RR Merlin head is simulated with a few mathematical models used in Formula 1 racing. These extremely simplified models make it possible to evaluate temperatures and pressures starting from very few data. The method is described in detail, along with the many experimental coefficients available from several years of design activity. A step by step approach is used to allow the comprehension of this method that was developed by the Authors. The choice of the RR Merlin was dictated by the public availability of experimental data on temperatures. In fact, in the case of the RR Merlin XX, very reliable experimental results are available in NACA TN 2069. A reverse engineering process was applied on a rescued RR Merlin XX head. An accurate redesign was performed to obtain a 3D model. Assembly instructions and tolerances were found on original Rolls Royce overhaul manuals. In this way assembly and working loads were calculated and simulated. Nonlinear FEA analysis was performed on this CAD model with extremely satisfactory results for the thermal loads. Well known criticalities of the original design were found. The results were compared with NACA results both for heat rejection and temperatures. However, the mechanical stresses proved to be more critical for simulation and evaluation. Therefore, they will be discussed in another, dedicated paper.

Keywords: CAD | FEA | Geometry | Optimization | Piston engine | Simulation | Thermal analysis

Abstract: An innovative method of tool wear assessment, based on the digitization of the cutting tool performed by a piezoelectric 3D scanner and on the analysis of the surfaces of a 3D model generated using the Reverse Engineering technique, has been developed. To this purpose, face milling experiments were carried out under dry cutting condition on AISI 420 B stainless steel using inserts in cemented carbide, with a two-layers coating (TiN and TiAlN). The time dependence of the insert wear was analysed by interrupting milling at predetermined time values. The proposed approach has been validated by comparing the output provided by the reverse engineering method to that measured experimentally by analysing the worn insert images obtained using a stereo microscope. An excellent agreement between the results given by the two different methodologies has been found. The worn tools have also been analysed using the scanning electron microscopy technique in order to understand the wear mechanisms operating during dry milling.

Keywords: CAD | dry cutting | FEG-SEM | milling process | Reverse engineering | tool wear

Abstract: Aim of this paper is to analyse and compare the characteristics of Feature Based and Direct Modeling techniques to determine their pros and cons for typical design processes. The first is one of the most common approach to create CAD models to be used for the machining phase of mechanical parts and assemblies. The second is a new method, alternative to the first one, based on a user-friendly approach, without rigid rules and constraints, that could represent the future of the CAD methodologies. Moreover, the Surface Modeling approach is analyzed and compared to the others, due to its common use in automotive and aeronautics fields. Considering the Feature Based Modeling as benchmark, three case studies were analysed to examine the peculiarities of these techniques, and to determine and highlight their advantages and their drawbacks. Several aspects were contemplated to perform the tests: the execution time for the realization of each operation, the easiness to create features and geometries, the possibility to adequately modify and upgrade the models and the number of operations needed to get the complete virtual prototype. In the end, the results were analysed and discussed focusing the attention on the possibility to adopt the Direct Modeling as substitute of the Feature Based and/or Surface Modeling and of the current CAD techniques.

Keywords: CAD | Direct modeling | Feature based modeling | Fuselage | Main landing fear | Surface modeling | Top-down approach | Virtual prototyping | Wing

Abstract: In this work we present a preliminary study on a system able to design automatically sockets for lower-limb prosthesis. The socket is the most important part of the whole prosthesis and requires a custom design specific for the patient’s characteristics and her/his residuum morphology. The system takes in input the weight and the lifestyle of the patient, the tonicity level and the geometry file of the residuum, and creates a new model applying the correct geometric deformations needed to create a functional socket. In fact, in order to provide the right fit and prevent pain, we need to create on the socket load and off-load zones in correspondence of the critical anatomical areas. To identify the position of such critical areas, several neural networks have been trained using a dataset generated from real residuum models.

Keywords: CAD | Lower limb prosthesis | Neural network | Prosthetic socket

Abstract: Nowadays, the creation of methodologies and tools for facilitating the 3D reproduction of artworks and, contextually, to make their exploration possible and more meaningful for blind users is becoming increasingly relevant in society. Accordingly, the creation of integrated systems including both tactile media (e.g., bas-reliefs) and interfaces capable of providing the users with an experience cognitively comparable to the one originally envisioned by the artist, may be considered the next step for enhancing artworks exploration. In light of this, the present work provides a description of a first-attempt system designed to aid blind people (BP) in the tactile exploration of bas-reliefs. In detail, consistent hardware layout, comprising a hand-tracking system based on Kinect® sensor and an audio device, together with a number of methodologies, algorithms and information related to physical design are proposed. Moreover, according to experimental test on the developed system related to the device position, some design alternatives are suggested so as to discuss pros and cons.

Keywords: 3D reconstruction | Blind people | Hand-tracking system | Kinect sensor

Abstract: The stylistic design of new industrial products often starts from shaded handmade sketches which, usually, need to be converted into 3D digital models by using CAD software packages for the subsequent design phases. This conversion often represents the bottleneck of the whole development process. Shape from Shading (SFS), which attempts to recover the 3D geometry of an object starting from a single shaded representation, is potentially capable of speeding-up the 3D conversion. However, existing approaches prove to be extremely unstable and error prone mainly due to the under-determination of the SFS problem. In order to increase the performance of shading based reconstruction authors propose a step-by-step variational-based approach. In particular, the problem is solved into multiple steps, each one providing the initialization for the following, so that the solution gradually converges towards the final surface. Tested against a set of case studies, the method proved its effectiveness.

Keywords: 3D design | Computer aided design | Numerical optimization | Shape from shading | Stylistic content | Variational approach

Abstract: Minimization techniques are widely used for retrieving a 3D surface starting from a single shaded image i.e., for solving the shape from shading problem. Such techniques are based on the assumption that expected surface to be retrieved coincides with the one that minimize a properly developed functional, consisting of several contributions. Among the possible contributes defining the functional, the so called "smoothness constraint" is always used since it guides the convergence of the minimization process towards a more accurate solution. Unfortunately, in areas where actually brightness changes rapidly, it also introduces an undesired over-smoothing effect. The present work proposes two simple yet effective strategies for avoiding the typical over-smoothing effect, with regards to the image regions in which this effect is particularly undesired (e.g., areas where surface details are to be preserved in the reconstruction). Tested against a set of case studies the strategies prove to outperform traditional SFS-based methods.

Keywords: 3D model | Minimization | Shape from shading | Smoothing | Smoothness constraint | Variational approach

Abstract: The development of the Theory of Inventive Problem Solving (TRIZ) has not followed the usual patterns of scientific validation required by engineering methods. Consequently, its outreach within engineering design is interpreted differently in the scholarly community. At the same time, the claimed powerful support in tackling technical problems of any degree of difficulty conflicts with TRIZ diffusion in industrial settings, which is relatively low according to insights into product development practices. The mismatch between ambitious goals and moderate spill-over benefits in the industry ranges among the various open issues concerning TRIZ, its way of thinking, its effectiveness, the usability of its tools. In order to provide a general overview of TRIZ in science, the authors have attempted to analyse reliable and influential sources from the literature. The performed survey includes the top 100 indexed publications concerning TRIZ, according to the number of received citations. Variegated and poorly interconnected research directions emerge in the abundant literature that tackles TRIZ-related topics. The outcomes of the investigation highlight the successful implementation of TRIZ within, among the others, biomimetics and information processing. The traditional borders of mechanical and industrial engineering have been frequently crossed, as the use of TRIZ is also witnessed in the domain of business and services. At the same time, computer-aided platforms represent diffused attempts to boost TRIZ diffusion and applicability.

Keywords: Computer-Aided Innovation | Conceptual design | Industrial practice | Information processing | TRIZ

Abstract: The work described in the paper is motivated by the lack of computer-aided tools to support Product Planning and, more specifically ideation processes of New Product Development (NPD) initiatives. The domain is populated by software applications aimed at managing and organizing Product Planning activities, which thus poorly contribute to the definition of new product characteristics, and models to stimulate novel ideas. The latter face limitations in terms of overlooked implementation with CAD tools supporting the following NPD phases and poor exploration of the design space. The authors propose an original method and software prototype capable to provide a wide range of stimuli, whose testing demonstrated much better results than traditional approaches in terms of quantity and variety of generated ideas.

Keywords: CAD | idea generation | New Product Development | product attributes | Product Planning | Value Dimensions

Abstract: The manuscript illustrates a method, implemented in a computer application, which supports the identification of new product features in the early phases of engineering design cycles. In the practice, such a task is commonly carried out through cognitive techniques that generate random and unstructured stimuli. These approaches and the computer-aided tools that implement them suffer from a scarce exploration of the design space. This criticality is faced by introducing an original classification of value drivers, thus organizing a large set of concepts consisting of stimuli for generating new product ideas. The proposed method combines the concepts belonging to different categories of the classification in order to identify scenarios in which the product can provide unprecedented benefits for customers and other stakeholders. Experiments in academia and industry show the capability of the developed method and prototype software to increase the number and the novelty of ideas, reveal previously overlooked drivers for customer satisfaction and enhance the definition of stimulated design requirements.

Keywords: Computer-Aided Design | Idea stimulation | New Product Development | Product attributes | Product Planning | Value dimensions

Abstract: Despite of the widespread of annotated 3D virtual models, it is still important to produce engineering drawings for a correct communication among the people of the design and manufacturing chain. Automatic drafting through meta drawing definitions, called Drafting Schemes, is proposed in this paper to save time when drawing becomes a repetitive task. The approach produces drafts with a predetermined content in terms of views arrangement and dimensioning strategy, and guarantees robust results to the variations of the input geometry. In fact, the geometrical entities referenced by the generated dimensions are retrieved through dedicated search algorithms based on recognition of geometric features of the input model. The approach has been implemented and tested on a family of gear motors showing feasibility and good results in terms of drafting time savings.

Keywords: Design Automation | Drafting | Feature Recognition | Knowledge Based Systems

Abstract: Technical knowledge and experience are intangible assets crucial for competitiveness. Knowledge is particularly important when it comes to complex design activities such as the configuration of manufacturing systems. The preliminary design of manufacturing systems is subject to a huge variability of inputs and outputs and involves decisions which must satisfy many competing requirements. This early engineering phase relies mostly on experience of designers and engineers and is associated with long lead times and high probability of mistakes. Knowledge-Based Engineering (KBE) and knowledge representation techniques are considered to be a successful way to tackle this design problem at an industrial level. This paper presents a methodology to support the configuration of powertrain assembly lines, reducing design times by introducing a best practice for production systems provider companies. The methodology is developed in a real industrial environment, introducing the role of a knowledge engineer. The approach includes extraction of existing technical knowledge and implementation in a knowledge-based software framework. The framework is then integrated with other software tools allowing the first phase design of the line including the line technical description and a 2D and 3D CAD line layout. The KBE application is developed and tested on a specific powertrain assembly case study for which existing knowledge is collected, formalised, implemented in the application and integrated with existing tools. Finally, the paper presents a first validation among design engineers, comparing traditional and new approaches and estimating a cost-benefit analysis useful for future possible KBE implementations.

Keywords: Design automation | Knowledge acquisition | Knowledge-based engineering | Powertrain assembly lines

Abstract: Persian architecture is characterised by shapes and patterns, which can be analysed through mathematical models. Beside 2D patterns, many of the traditional geometric ornaments are realised on 3D surfaces such as domes or vaults. Literature mainly addresses the 3D problem by means of a 2D scheme, which is an important and synthetic representation but is not exhaustive and lacks of clarity. This paper proposes a framework based on the integration of 2D drawings, as in the traditional approach, and a photogrammetric 3D model based on a sample of standard resolution images (tourist pictures). The framework is tested on a muqarnas, a characteristic Persian ornament, in order to study and analyse its modular design and hierarchy of elements. As a case study, the entrance iwan of the Shah Mosque in Isfahan, Iran, is considered. The result is a link between the 3D patterns and the geometry of architectural elements, which completes and overcomes their schematic 2D representation.

Keywords: CAD modelling | Geometric analysis | Iwan | Modules | Muqarnas | Persian ornament | Representation of architecture

Abstract: A 3D automatic facial expression recognition procedure is presented in this work. The method is based on point-by-point mapping of seventeen Differential Geometry descriptors onto the probe facial depth map, which is then partitioned into seventy-nine regions. Then, features such as mean, median, mode, volumes, histograms are computed for each region and for each descriptor, to reach a varied large set of parameters representing the query face. Each set of parameters, given by a geometrical descriptor, a region, and a feature, form a trio, whose featuring numerical values are compared with appropriate thresholds, set via experimentation in a previous phase by processing a limited portion of the public facial Bosphorus database. This allows the identification of the emotion-based expression of the query 3D face among the six basic ones (anger, disgust, fear, joy, sadness, surprise). The algorithm was tested on the Bosphorus database and is suitable for applications in security, marketing, medical. The three-dimensional context has been preferred due to its invariance to different lightening/make-up/camouflage conditions.

Keywords: 3D face | Differential geometry | Emotions | Face expression recognition (FER) | Facial expression recognition | Shape index

Abstract: This study proposes a novel approach to automatically localise 11 landmarks from facial RGB images. The novelty of this method relies on the application, i.e., point-by-point mapping, of 11 differential geometry descriptors such as curvatures to the three individual RGB image components. Thus, three-dimensional features are applied to bidimensional facial image representations and used, via thresholding techniques, to extract the landmark positions. The method was tested on the Bosphorus database and showed global average errors lower than five millimetres. The idea behind this approach is to embed this methodology in state-of-the-art 3D landmark detection methods to accomplish a full automatic landmarking by exploiting the advantages of both 2D and 3D data. Some landmarks such as pupils are arduous to be automatically extracted only via three-dimensional techniques. Thus, this method is intended as a bridging-the-gap preliminary technique that takes advantages of 2D imaging only for integrating advanced landmark localisation methodologies.

Keywords: Differential geometry | Face analysis | Facial landmarks | Landmark localisation | RGB images

Abstract: Having environmental indications such as those provided by Life Cycle Assessment (LCA), while designing a product would reduce the time required by the trial-and-error approach resulting from environmental checks only at the end of the process, directing the development towards more sustainable solutions from the beginning. To achieve this, the design and environmental analysis should be more integrated, as well as the respective tools. The project idea discussed in this paper aims to overcome this barrier by defining an XML (eXtensible Markup Language) structure designed to carry Life Cycle Inventory data from Computer Aided Design (CAD) tools to Life Cycle Assessment tool. The idea is to exploit overlapping data between the CAD system and LCA instruments, which are currently not being considered. This process will contribute to the reduction of time required for data input and the amount of mistakes.

Keywords: CAD | Eco-design | LCA | LCI

Abstract: Digital documentation and high-quality 3D representation are always more requested in many disciplines and areas due to the large amount of technologies and data available for fast, detailed and quick documentation. This work aims to investigate the area of medium and small sized artefacts and presents a fast and low cost acquisition system that guarantees the creation of 3D models with an high level of detail, making the digitalization of cultural heritage a simply and fast procedure. The 3D models of the artefacts are created with the photogrammetric technique Structure From Motion that makes it possible to obtain, in addition to three-dimensional models, high-definition images for a deepened study and understanding of the artefacts. For the survey of small objects (only few centimetres) it is used a macro lens and the focus stacking, a photographic technique that consists in capturing a stack of images at different focus planes for each camera pose so that is possible to obtain a final image with a higher depth of field. The acquisition with focus stacking technique has been finally validated with an acquisition with laser triangulation scanner Minolta that demonstrates the validity compatible with the allowable error in relation to the expected precision.

Keywords: Cultural heritage | Focus stacking | Photogrammetry | Small artefacts | Structure from motion

Abstract: The present work aims at the development of an advanced control system implemented through Adams/View-Matlab/ Simulink co-simulation for a high-performance motorcycle dynamics study. In particular, the purpose of this study is to create a model able to consider several aspects of the rider-motorbike dynamic simulation and its control system, generally treated separately in the literature, making also use of an original and accurate modelling of the rider. From a previous multi-body model of motorcycle/virtual rider, developed by the authors, a flexible tool is created to simulate system dynamics to follow any trajectory at a prescribed velocity profile. Considering high-performance motorcycle dynamics are greatly influenced by the rider's weight, his movements have been accurately replicated to obtain the most realistic results. To simulate the passive impedance of rider's arms, a torque was applied to the steering as per the literature. The aerodynamic force was modelled as a function of kinematics variables and rider's posture. The control system is very flexible and adaptable to different manoeuvres realistically reproducing engine and braking performance, steering torque and rider movements. Numerical results show that the control system can accurately direct the motorcycle/ rider system along an entire lap of the Monza circuit, following a desired path at a given velocity profile. The model developed allows a complete view of the motorbike-rider dynamic behaviour thus being useful during both design phase and set-up, with a considerable saving in terms of both cost and time; it can also evaluate the influence on the system dynamics of riders with different anatomical characteristics and driving styles.

Keywords: Co-simulation | Control | Multibody | Path tracking | Rider/motorcycle

Abstract: The geometric segmentation of a discrete geometric model obtained by the scanning of real objects is affected by various problems that make the segmentation difficult to perform without uncertainties. Certain factors, such as point location noise (coming from the acquisition process) and the coarse representation of continuous surfaces due to triangular approximations, introduce ambiguity into the recognition process of the geometric shape. To overcome these problems, a new method for geometric point identification and surface segmentation is proposed. The point classification is based on a fuzzy parameterization using three shape indexes: the smoothness indicator, shape index and flatness index. A total of 11 fuzzy domain intervals have been identified and comprise sharp edges, defective zones and 10 different types of regular points. For each point of the discrete surface, the related membership functions are dynamically evaluated to be adapted to consider, point by point, those properties of the geometric model that affects uncertainty in point type attribution. The methodology has been verified in many test cases designed to represent critical conditions for any method in geometric recognition and has been compared with one of the most robust methods described in the related literature.

Keywords: Discrete differential geometry | Discrete surfaces | Geometric segmentation

Abstract: The present paper proposes a new method for axis identification in discrete axially symmetrical geometric models. This method is based on-a-never-used-before property of the axially symmetrical surfaces for which the symmetry line of any section curve of the surface (or of a portion of it in the case of an incomplete axially symmetrical surface) always intersects the axis of symmetry of the surface. Thus the working principle of the method makes it very robust to local defectiveness, measurement noise and outliers. In order to compare it with the most cited methods presented in literature, several types of tests have been designed and performed. The robustness of those methods, on the one hand, has been evaluated by defining the Statistical Confidence Boundary at 1σ confidence level. The trueness of the method, on the other hand, has been evaluated on geometric models obtained by measuring real objects. The high robustness, which characterizes the proposed method, makes it particularly suitable for product geometric inspection where high accuracy is required.

Keywords: Axis identification | Geometric inspection

Abstract: The research work presented in this paper is part of an innovative framework that deals with the design process of lower limb prostheses. The quality of the whole prosthesis depends on the comfort of the socket, which realizes the interface between the patient body and the mechanical parts. We developed a CAD system, named Socket Modelling Assistant that guides the user during the design of the socket, exploiting domain knowledge and design rules. In this work we present a preliminary study that describes the implementation of a software module able to automatically identify the critical areas of the residuum to adequately modify the socket model and reach the optimal shape. Once the critical areas have been identified, the Socket Modelling Assistant can apply proper geometry modifications, in order to create the load and off-load zones for a good pressure distribution over the residual limb.

Keywords: CAD | Lower limb prosthesis | Neural network | Prostheses socket

Abstract: The paper concerns the use of integrated methodologies and tools to perform innovative human centered development of products. Digital simulation of ergonomics by means of DHM is shown together with advanced tools for design, taking into account Knowledge-based systems, Design Automation and design of highly customized goods. Two different applications of the proposed approach are described, the first refers to an industrial product, the second to the medical domain. Both applications, even if belonging to completely different fields benefit from putting the human at the center of the developing paradigm from the very first step of product development. Some results and discussion highlight benefits and limitation of the approach and of the adopted tools.

Keywords: Design Automation | Digital human modelling | Ergonomics | Human centered design | Knowledge-based systems | Lower limb prosthesis

Abstract: This paper explores a possible integration of some ancillary systems of helium-cooled lithium lead (HCLL) and helium-cooled pebble-bed (HCPB) test blanket modules in ITER CVCS area. Computer-aided design and ergonomics simulation tools have been fundamental not only to define suitable routes for pipes, but also to quickly check for maintainability of equipment and in-line components. In particular, accessibility of equipment and systems has been investigated from the very first stages of the design using digital human models. In some cases, the digital simulations have resulted in changes in the initial space reservations.

Keywords: CAD | Design for maintainability | Digital human modeling | Piping layout design

Abstract: Seagrass meadows are complex ecosystems representing an important source of biodiversity for coastal marine systems, but are subjected to numerous threats from natural and human-based influences. Due to their susceptibility to changing environmental conditions, seagrasses are habitually used in monitoring programmes as biological indicators to assess the ecological status of coastal environments. In this paper we used a non-destructive photo mosaicing technology to quantify seagrass distribution and abundance, and explore benefits of micro-cartographic analysis. Furthermore, the use of photogrammetric tools enhanced the method, which proved to be efficient due to its use of low-cost instruments and its simplicity of implementation. This paper describes the steps required to use this method in meadows of Posidonia oceanica, including: i) camera calibration procedures, ii) programming of video survey, iii) criteria to perform sampling activities, iv) data processing and micro-georeferenced maps restitution, and v) possible study applications.

Keywords: Mapping | Photo mosaicing | Photogrammetry | Posidonia oceanica | Seagrass | Underwater photography

Abstract: Seagrass communities are considered one of the most productive and complex marine ecosystems. Seagrasses belong to a small group of 66 species that can form extensive meadows in all coastal areas of our planet. Posidonia oceanica beds are the most characteristic ecosystem of the Mediterranean Sea, and should be constantly monitored, preserved and maintained, as specified by EU Habitats Directive for priority habitats. Underwater 3D imaging by means of still or video cameras can allow a detailed analysis of the temporal evolution of these meadows, but also of the seafloor morphology and integrity. Video-photographic devices and open source software for acquiring and managing 3D optical data rapidly became more and more effective and economically viable, making underwater 3D mapping an easier task to carry out. 3D reconstruction of the underwater scene can be obtained with photogrammetric techniques that require just one or more digital cameras, also in stereo configuration. In this work we present the preliminary results of a pilot 3D mapping project applied to the P. oceanica meadow in the Marine Protected Area of Capo Rizzuto (KR, Calabria Region-Italy).

Keywords: 3D mapping | 3D reconstruction | Optical instruments | Posidonia oceanica | Quality status

Abstract: This paper presents some experimentations, which have been conducted in the submerged archeological Park of Baiae, aimed to identify the problems related to the underwater 3D documentation process. The first test has been addressed to verify if a dense stereo mapping technique, usually employed in terrestrial and aerial applications, might be employed in critical underwater conditions by assessing the influence of different factors on the results. In the second test, the accuracy of the 3D model obtained through this technique has been evaluated. The third test deals with the geo-localization of the 3D models, conducted by merging the optical and acoustic data, through a multi-resolution bathymetric map of the site as a reference.

Keywords: 3D documentation | 3D model accuracy | 3D reconstruction | Baiae archeological park | Optical and acoustic data merging

Abstract: The dynamics of a high-performance motorcycle are greatly influenced by the rider's weight and movements especially when the power-to-weight ratio is very high. Generally in motor vehicles, the driver's/rider's weight is a significant fraction of the entire system. This work is about ADAMS/View multibody modelling of a motorcycle and virtual rider who simulates handlebar interaction and saddle sliding. In the literature, the rider's influence is unrealistic being limited to considering him as a concentrated mass or in other cases as a fixed passive system. Even vehicle modelling is often inaccurate, referring at best to simplified models of rigid bodies. In this work, the vehicle and rider have been accurately modelled to most realistically reproduce the dynamic behaviour of the system. The motorcycle was modelled with 12 bodies incorporating concentrated flexibility for the two suspension units and considering the chassis as a flexible body using modal synthesis. The virtual rider is made up of 15 rigid bodies and has 28 degrees of freedom. To study the effects on the motorcycle of the rider's movements as well as the motorcycle's dynamics and performance, a monitoring system similar to that in the literature was used to read handlebar torque and engine and braking torque. Furthermore, in the literature there are simulations of standard manoeuvres whereas in this work an entire lap of Monza was simulated. There were simulations of a fixed and mobile rider validating the model in advance and thereafter monitoring the most significant dynamic parameters. The multibody model provides useful results at the design phase and insights into the whole vehicle/rider dynamic to setup all the reference parameters for immediately evaluating system effects.

Keywords: Multibody | Path tracking | Rider's effects | Rider-motorcycle system | Steering torque

Abstract: Although 3D models are useful to preserve the information about historical artefacts, the potential of these digital contents are not fully accomplished until they are not used to interactively communicate their significance to non-specialists. Starting from this consideration, a new way to provide museum visitors with more information was investigated. The research is aimed at valorising and making more accessible the Egyptian funeral objects exhibited in the Sforza Castle in Milan. The results of the research will be used for the renewal of the current exhibition, at the Archaeological Museum in Milan, by making it more attractive. A 3D virtual interactive scenario regarding the "path of the dead", an important ritual in ancient Egypt, was realized to augment the experience and the comprehension of the public through interactivity. Four important artefacts were considered for this scope: Two ushabty, a wooden sarcophagus and a heart scarab. The scenario was realized by integrating low-cost Virtual Reality technologies, as the Oculus Rift DK2 and the Leap Motion controller, and implementing a specific software by using Unity. The 3D models were implemented by adding responsive points of interest in relation to important symbols or features of the artefact. This allows highlighting single parts of the artefact in order to better identify the hieroglyphs and provide their translation. The paper describes the process for optimizing the 3D models, the implementation of the interactive scenario and the results of some test that have been carried out in the lab.

Keywords: 3D modelling | Cultural Heritage | Leap Motion | Oculus Rift | Unity | Virtual Reality | Visualisation

Abstract: Press and sinter is a near net-shape technology, and its cost effectiveness is strictly related to the geometrical and dimensional precision of the component itself. In this work an analytical model to describe the dimensional variations due to the sintering process of iron components has been proposed and discussed. This model has been developed using experimental data coming from a well designed sampling. The sampling is a set of axisymmetric geometries, rings and cylinders, having different diameters and heights. The different features (diameters and heights) have then been compared with the dimensional variations to study the influence of the geometry on the dimensional variations. Every sample has been measured both in the green state and after the sintering process. The dimensional variations concerning the diameters and the heights have been evaluated. The measuring procedure has been implemented using a coordinate measuring machine. The sintering process has been carried at three different temperatures under the same operating conditions. The anisotropy of the dimensional variations has been studied and described within the proposed model, introducing the anisotropy parameter (K). Basically the parameter K identifies the difference between the dimensional variations occurring in an ideal isotropic volumetric change and the actual anisotropic volumetric variation. The model can describe the difference between the dimensional variations occurring on the compaction plane (diameters) and the dimensional variations occurring along the compaction axis (height). The effect of the geometry and the sintering temperature on the anisotropy of the dimensional variations has been evaluated.

Keywords: Anisotropy | Dimensional control | Modeling | Process capability | Sintering

Abstract: Purpose-High pressure die casting is a widely used industrial process to manufacture complex-shaped products in light alloys. Virtual prototyping techniques, especially numeric-based simulations of the casting process, allow the die filling process to be evaluated and help faster optimization of the gating system, which is the most critical element of the mould. The purpose of this paper is to present a four step approach to design optimal moulds taking advantage of the simulation tools. Design/methodology/approach-No formalized method to design an optimal gating system is available yet and the majority of the studies aim to optimize existing geometries or to choose from alternative solutions. Rather than optimizing the geometries of predefined designs by running attempt trials, the proposed approach defines a procedure to position cavities, gating systems and, finally, to determine the whole mould geometry. Findings-The approach is demonstrated through three different industrial applications. The design of a six-cavity mould for gas cooking burners is reported at first. Then, two test cases, a cup and a radiator, are reported for showing different arrangements of the gating system. The reached quality of the mould design has been assessed using metallographic analyses of the casts. Originality/value-The design of a mould is strictly correlated to its product and mainly based on a trial-and-error approach. Numerical simulations offer a powerful and not expensive way to study the effectiveness of different die designs and filling processes. The paper proposes a structured approach for the definition of the gating system. It ultimately leads to improvements in both product quality and process productivity, including more effective control of the die filling and die thermal performance.

Keywords: Gating system | High pressure die casting | Numerical simulation | Paper type Research paper | Shape optimization

Abstract: The present work had as its main aim to carry out a study of the high lift of an unconventional aircraft of the '40s, the Vought V-173 Flying Pancake. To obtain this result the Authors used the Computational Fluid Dynamics (CFD) software SolidWorks Flow Simulation. In particular, the CL-αand CD-αcurves have been interpolated from the points obtained from the simulations for different configurations of the V173 aircraft CAD model. In a first phase the aerodynamics of the aircraft was evaluated 'clean' without the presence of the propellers was analysed. In a second phase, the influence of the two large propellers was taken into account. The effect of the propeller was clearly shown especially at high AOA. These results were obtained from the direct comparison of the Lift-AOA and Drag-AOA curves for the unpowered and the powered condition. The CFD results confirmed the impression of high controllability of the powered aircraft up to AOA of 50°. This behavior with the extremely smooth stall gave the impression of an aircraft impossible to stall or to spin.

Keywords: CAD | CFD | Flying pancake | STOL | V173

Abstract: This paper introduces a method to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by 2 orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid since temperatures vary slowly when compared to pressure (load). In fact pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approach.

Keywords: CAD | FEA | Geometry | Optimization | Simulation

Abstract: Recreational vehicles (camper, vans and motorhomes) are equipped with service doors to access to specific areas such as water tank or luggage zone. As the state-of-the-art technology stands at present, two different typologies of service doors are manufactured: doors with plastic frames, obtained by injection molding, and doors with aluminum frames realized by extruded bars. Plastic frame-based doors are characterized by concealed hinges (i.e. hinges integrated in the frame), therefore resulting aesthetically pleasant to the final user. Unfortunately, they are basically produced in standard dimensions due to the complexity and costs of injection molding process; as a consequence the number of available measures in the market is really limited. Quite the reverse, aluminum frame-based doors can be produced in customizable formats by adjusting the bars length. The main drawbacks of this second typology of doors are that the cutting and bending machines, used to produce them, need to be periodically tuned in order to take into account possible environmental thermal variations and, moreover, in order to achieve 180° opening, the hinges are required to stick out the wall. Moving from these considerations, this work proposes a CAD/CAE-based design of an innovative service door based on a modular design where frames consist of extruded plastic bars, cut in required length, which are capable to comprise concealed hinges. Accordingly, the new door designed in the present work brings together the advantages offered by the standard solutions pushing forward the RV door technological state of the art.

Keywords: CAD | CAE | Service doors | Slam test

Abstract: Web-enabling technologies represent the next generation of design environments to design and manufacture complex systems, such as them characterizing contract furniture. In the context of web applications to facilitate and support teamwork in collaborative product development, the paper presents a CAD-based infrastructure for the 3D visualization of co-designed solutions, the on-line customization of furniture items and the creation of a shared relational database of products, architectural scenes and knowledge-based rules guiding configuration. A double-level geometry is presented to manage 3D web representation and product structure. A use case is adopted to show main platform functionalities and possible advantages for the extensible contract furniture cluster.

Keywords: CAD | Collaborative product development | Web-enabling technologies | WebGL

Abstract: Main target of this paper is to analyse the advantages in the use of the Direct Modeling in the Virtual Prototyping processes and in the multiphysics analyses with the help of Reverse Engineering procedures. It is a recent CAD technique that allows the creation and/or modification of models that don’t need parameters and constraints, as on the contrary happens in the Feature Based Modeling. So, it is possible to change the shapes and the dimensions of the original prototypes very easily. Hence, in this paper a methodology devised to acquire and modify a “reconstructed” (non-parametric) model to improve and then to submit it to FEM analysis is presented. Furthermore, it is realized and doesn’t even need the Feature Recognition phase of a typical Reverse Engineering process. In particular, this methodology was applied to a frame of a bicycle used as case study. Its shape was acquired by means of a laser scanner and its virtual prototype was “reconstructed”. In addition, starting from it, two alternative frames were obtained and then easily modified by means of the Direct Modeling techniques. Then, they were submitted to FEM analyses to get different solutions with less weight but similar mechanical performances. Afterwards, the ergonomics of the modified configurations was tested by means of different percentile virtual manikins to plan the physical prototyping of a new improved bicycle.

Keywords: Bicycle | CATIA manikin | DELMIA simulations | Direct modeling | Feature based modeling | Feature recognition | FEM analysis | Reverse engineering

Abstract: First target of this paper is to describe the design the behaviour of the final prototype before its manufacturing of an automotive semi-active differential based on the use of a and to predict its good performances and possible Magnetorheological Fluid (MRF). The MRF allows to control weaknesses. So the costs and the time to market of the new the locking torque and, consequently, to improve the vehicle handling. Second target is to propose a method grounded on a Close-Range Photogrammetry approach for the CAD modeling phase of the device ideated, alternative to the use of the typical Reverse Engineering (RE) techniques. In fact, although a Reverse Engineering process allows the complete 3D reconstruction of the external surfaces and features of a real object, it could often take a lot of time and, in some cases, could be affected by some approximations or errors. Furthermore, a model “reconstructed” could not be the best solution for multiphysics analyses, where the parametric geometry is needed for the modifications of all its features and dimensions for the optimization process in a very short time. For these reasons, in the case studied, the complete CAD prototype, created step by step, is needed and the photogrammetry can represent an interesting solution to enhance the virtual prototyping phase without repercussions on the quality of the results. Starting from the acquisition of particular “key points”, with an acceptable tolerance, the definition of the references (datum axes, curves, planes, centres of holes) needed for the CAD modeling, according to the Top-Down procedure, was possible. Once obtained the preliminary prototype, the final CAD model was created optimizing its dimensions and choosing the adequate materials. To evaluate the goodness of the procedure adopted, the MRF LSD geometry was reconstructed also by means of the Reverse Engineering techniques applied to the physical prototype of the new device ad hoc created. In particular, laser system acquisition and RE dedicated software were used. In this way the comparison between the photogrammetric and Reverse Engineering procedures (in terms of time spent and quality of the results) was allowed and so conducted. Lastly, the results of the FEM analyses carried out to validate the design process and the methodology ideated and adopted were showed.

Keywords: 3D CAD parametric modeling | Automotive differential | Direct modeling | FEM analysis | Magnetorheological fluid | Photogrammetry | Reverse engineering

Abstract: In this work a commercial reverse shoulder prosthesis has been redesigned to improve performances in terms of range of movements of the implant and stability to dislocation. A kinematic and mechanic study has been performed using a realistic solid model of the prothesised shoulder: in particular, all the components of the prosthesis have been acquired via a 3D laser scanner and inserted in a virtual humerus-glenoid system by reproducing the common surgical procedure. The final model has been used to measure the maximum angles of abduction and rotation of the arm and the shear forces that cause dislocation. Modifications proposed to the commercial prosthesis are: a different orientation of the cutting plane of the glenoid component and the interposition of a spacer to move the center of rotation of the arm.

Keywords: CAD modelling | Digital shape acquisition | Reverse shoulder prosthesis

Abstract: This paper proposes a design approach to support the designer during the environmentally sustainable redesign of any product that can be modeled in CAD environment. It is a systematic computer-aided design procedure based on the integration of (1) virtual prototyping tools (e.g., 3D CAD, FEA, structural optimization), (2) function modeling techniques, and (3) Life Cycle Assessment-LCA tools. The core of the approach is the configuration of structural optimization strategies specifically conceived to obtain lighter and more compact products, and therefore, more eco-sustainable. The objective of the proposed methodology is to support the designer in choosing the best triad shape-material-production in order to determine the minimum environmental impact and ensure the structural and functional requirements of the product. A case study is described to show the potential of the proposed methodology as well as a discussion of the results. © 2014 CAD Solutions, LLC.

Keywords: CAD | eco design | LCA | structural optimization

Abstract: Commonly used to produce the visual effect of full 3D scene on reduced depth supports, bas relief can be successfully employed to help blind people to access inherently bi-dimensional works of art. Despite a number of methods have been proposed dealing with the issue of recovering 3D or 2.5D surfaces from single images, only a few of them explicitly address the recovery problem from paintings and, more specifically, the needs of visually impaired and blind people. The main aim of the present paper is to provide a systematic method for the semi-automatic generation of 2.5D models from paintings. Consequently, a number of ad hoc procedures are used to solve most of the typical problems arising when dealing with artistic representation of a scene. Feedbacks provided by a panel of end-users demonstrated the effectiveness of the method in providing models reproducing, using a tactile language, works of art otherwise completely inaccessible.

Keywords: 2.5D model | Minimization techniques | Shape From Shading | Tactile model

Abstract: Design of products characterized by high stylistic content and organic shapes in the form of bas-relief (e.g. fashion accessories, commemorative plaques and coins) is traditionally performed starting from handmade drawings or photographs that are manually reproduced by highly skilled craftsmen such as sculptors and engravers and finally digitized by means of 3D scanning. Several Computer-based procedures have been devised with the aim of speeding up this process, which is considerably time consuming, subjective and costly; these are mainly based on image processing techniques such as embossing, enhancement, histogram equalization or dynamic range, also implemented in CAD-based commercial software. However, these approaches are characterized by several limitations preventing them from providing a "correct" final geometry. In view of that, the present work describes a novel method for the creation of digital bas-reliefs from a single image using a Shape From Shading (SFS) based approach with interactive initialization. Image processing-based techniques and minimization SFS methods are first used in order to retrieve a rough version of the objective surface; successively, this is used as initialization for the final reconstruction algorithm. Tested on a set of case studies, the method proved to be effective in providing satisfactory digital bas-relief from single images. © 2013 © 2013 CAD Solutions, LLC.

Keywords: digital bas-relief | image processing | shape from shading | shape retrieval

Abstract: In the aerospace sector, tolerance allocation and inspection of many components must provide not only for ease of manufacturing and cost reduction but also for reliability and safety requirements. Computer Aided Tolerancing and Inspection (CAT&I) methods based on Reverse Engineering techniques may enhance production quality assessment with significant reduction of the time-to-market. This paper presents an original reverse engineering methodology that is being developed to achieve the complete automation of the inspection process starting from the design requirements (dimensional and geometrical tolerances) as they generally appear in the component's official drawings. After a brief presentation of the proposed methodology and its possible implementation oriented to non-planar surface recognition, an aeronautical component made by beta-forging of Ti6Al4V Titanium Alloy powders is presented as test case. The discussion of the procedure allows to point out its benefits in terms of (a) more efficient management of the inspection process and data consolidation; (b) more thorough comprehension of the real component; and (c) a better understanding of possible feedbacks to be applied in design or manufacturing. Finally some remarks about the limits of the proposed methodology are shown and possible enhancements, that have been already planned to be applied, will be described. © 2014 IEEE.

Keywords: beta-forging | Computer Aided Tolerancing and Inspection | Reverse Engineering | Segmentation | Ti6Al4V Titanium Alloy powders

Abstract: ABSTRACT: This paper presents a point cloud segmentation based on a spatial multiresolution discretisation that is derived from hierarchical space partitioning. Through part type recognition it aims to simplify Computer Aided Tolerance Inspection of electromechanical components avoiding cloud-CAD model registration. A voxel structure subdivides the point cloud. Then, through a suitable surface partitioning, it is linked to component volumes by means of the morphological components of the binary image that is derived from voxel attributes (‘true state’ if points are included in a specific cluster or ‘false state’ if they are not). The proposed approach is then applied on a din-rail clip of a breaker, made by injection moulding. This case study points out the suitability of the approach on box-shaped components or with normal protrusions, and its limits concerning the assumptions of the implementation.

Keywords: computer aided tolerance inspection | reverse engineering | segmentation

Abstract: Our goal is to allow the creators to focus on their creative activity, developing their ideas for physical products in an intuitive way. We propose a new CAD system allows users to draw virtual lines on the surface of the physical object using see-through AR, and also allows users to import 3D data and make its real object through 3D printing.

Keywords: 3D printing | AR/MR | CAD | Collaboration

Abstract: 3D reconstructions of small objects are more and more frequently employed in several disciplines such as medicine, archaeology, restoration of cultural heritage, forensics, etc. The capability of performing accurate analyses directly on a three-dimensional surface allows for a significant improvement in the accuracy of the measurements, which are otherwise performed on 2D images acquired through a microscope. In this work we present a new methodology for the 3D reconstruction of small sized objects based on a multi-view passive stereo technique applied on a sequence of macro images. The resolving power of macro lenses makes them ideal for photogrammetric applications, but the very small depth of field is their biggest limit. Our approach solves this issue by using an image fusion algorithm to extend the depth of field of the images used in the photogrammetric process. The paper aims to overcome the problems related to the use of macro lenses in photogrammetry, showing how it is possible to retrieve the camera calibration parameters of the sharp images by using an open source Structure from Motion software. Our approach has been tested on two case studies, on objects with a bounding box diagonal ranging from 13.5. mm to 41. mm. The accuracy analysis, performed on certified gauge blocks, demonstrates that the experimental setup returns a 3D model with an accuracy that can reach the 0.05% of the bounding box diagonal. © 2013 Elsevier Masson SAS.

Keywords: 3D reconstruction | Cultural heritage | Digital documentation | Image fusion | Macro lens | Small objects

Abstract: The aim of this work is the realisation of an automatic generalised procedure for creating a parametric easily manageable and fully automatic FEM model to predict the mechanical properties of composites having cylinder-shaped reinforcing fibres characterised by a complex morphology. A three-dimensional finite element RVE (Representative Volume Element) has been realised by means of an original modified RSA algorithm (Random Sequential Adsorption algorithm) which allows to reproduce, with high degree of approximation, the intrinsic geometrical and statistic characteristics of the examined composite, directly influenced by the particular real forming process and, therefore, the phenomena which characterise the mechanical response of the materials constituting the therein coexisting phases. The implemented procedure is completely automatic, because it requires an external operator barely for the insertion of a minimum number of geometrical information in Input. This insertion pertains to the geometrical information concerning the composite to simulate and to the information about the mechanical properties of the coexisting phases. In Output the procedure provides directly, through a single run, the whole stiffness matrix calculated with two different numerical homogenisation tools, using periodic boundary conditions. The procedure allows a minimisation of the RVE dimensions which give acceptable scatters, thanks to an original "isotropic criterion" based on the minimisation of a particular function. It was also introduced a method of calibration of those Input data which may be affected by geometrical constraints, introduced to face the basic assumptions of the algorithm. The first release of this algorithm has been already implemented, in a previous published work, see Cricrì et al. (2012). Such a procedure results potentially much more versatile than most of the existing models; it is facilely adaptable to investigations beyond the mechanical characterisation and covers other areas of interest related to composites. © 2013 Elsevier B.V. All rights reserved.

Keywords: Fibres | Finite element analysis (FEA) | Modelling | Nanocomposites

Abstract: Class-A curves show very appreciable features in terms of smoothness and curvature trend that is commonly perceived as high quality profiles. These curves are commonly sketched by experienced operators, but at the present day no tools are available to transform a B-spline into a Class-A curve. The k-neigh-fast is an improved version of k-neighbours algorithm, described in Amati et al. (Comput Graph 30(3):345-352, 2006), aiming to transform a B-spline non-Class-A slope into a B-spline Class-A curve by manipulating a group of k geometric coefficients. Once the level of detail (LOD) representation of a curve has been computed, the k-neigh-fast algorithm, detects those control points representing non-Class-A imperfections. At each LOD, the algorithm individuates the detail coefficient maximizing the internal functional. Then k-neighbours has been modified applying filtering criteria. A control step starts to verify the transformation from a non-Class-A curve into a Class-A shape. This process is repeated until the chosen stopping condition is satisfied. The final shape with improved smoothness and monotonic curvature is achieved through manual procedure. This paper reports results dealing on an improved and faster wavelet-based LOD filtering implementation used to generate very smooth set of profiles that own to Class-A set. The LODs representation allows to divide curves into their coarser least-square approximations and details coefficients. The extraction and manipulation of details with multi-level filtering, allows to determine geometric imperfections. This method has been tested to the smoothing of the hull profile of ships: results are good since the non-A-curve are well converted in smoother lines. A more efficient implementation, based on a flexible LOD representation led to prove many benefits of this techniques; the tests performed exploiting a computer program implementation have demonstrated very good results in most of simulations considered. © 2012 Springer-Verlag France.

Keywords: CAD | Class-A curves | Design | Smoothing optimization | Wavelets

Abstract: In a scenario of small and customized production of electric vehicle, it is important to set methods and tools to evaluate the Li-Ion cells heat source in EV battery. The main problem of the new lithium batteries is represented by the need to keep the battery packs at uniform and constant temperatures and avoid peaks of temperatures which cause degradation of performance and safety problem. The main issue concerns the characterization of a thermal model to calculate the heat generated by electrochemical reactions in a single battery cell. In order to achieve this objective, electrical tests have been conducted to obtain the parameters such as voltage curves, open circuit voltage, and capacity for different type of Li-Ion cells and different rate of current in charge and discharge. During experiments, the use of an IR camera allows to acquire real temperature data under working conditions. These tests concern one cell per time, analyzed in natural convection condition at constant external temperature. The heat generation is evaluated solving the analytical thermal formula which depends on the current rate. The approach has been validated comparing the calculated temperature values with experimental data. The proposed methodology allows to determine the heat generated and temperature for different working condition.

Keywords: heat exchange | lithium battery | modeling

Abstract: Generally a part of electric vehicle diffusion is still based on marketing of cars and vans suitable for specific use like work vehicles. A flexible design methodology is required to support rapid prototyping and product customization in the market of tailored EV/PHEV. The research focuses the cooling simulation for a PHEV Li-Ion battery. The thermal analysis is based on the physical parameters of the single cell and on the experimental data. The proposed methodology concerns firstly an analytical approach which evaluates the average heat generated by a single cell during working condition. Then the proposed virtual prototyping analysis has been divided into two levels: the thermal simulation of one cell, and the CFD analysis of a battery module. This workflow has been applied to support the design of a battery pack for a prototypal ecological hybrid vehicle. That test case vehicle is a small van, used for the curbside collection, which has in parallel an internal combustion engine and an electric motor supplied by a LFP battery with small cylindrical cells. The analysis concerns one of the four module which constitutes the whole battery pack. The virtual model has been parameterized and the behavior of air cooling system has been evaluated through virtual tools.

Keywords: cooling | lithium battery | modeling | PHEV | simulation

Abstract: Design of assembly lines is a knowledge intensive process relying significantly on experience of designers and engineers, lessons learned and complex sets of rules. This complicated design process is associated with high costs, long lead times and high probability of risks and reworks. Knowledge Based Engineering (KBE) and knowledge representation techniques are considered to be a successful way to tackle this design problem. This paper presents a methodology to support the configuration of assembly lines, mitigating risks and costs by introducing a best practice for global production systems provider companies. A set of system engineering rules is extracted from interviews and domain best practices and knowledge about product domain and design process is formalized. These rules will be implemented in a user-friendly platform allowing the design of first phase line layout by taking the defined system requirements (e.g. cycle time) as input. Then, the KBE approach is extended to a specific case study taken from the powertrain sector. Here, the collected knowledge on an assembly line and its design process is presented.

Keywords: Assembly Line | Design Automation | Knowledge Based Engineering | Powertrain Systems

Abstract: This paper introduces a method to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by two orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid since temperatures varies slowly when compared to pressure (load). In fact pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approach [1-4].

Keywords: CAD | FEA | Geometry | Optimization | Simulation

Abstract: Design of new industrial objects characterized by high stylistic content often starts from sketches or images of the product to be, subsequently, represented in a 3D digital form by using CAD software. To speed up this phase, a number of methods for automatic or semi-automatic translation of sketches or images into a 3D model have been devised all over the world also for reverse engineering purposes. When the image shading is a crucial information for recovering the final 3D shape, Fast Marching is recognized to be among the best method to date, especially for frontally illuminated scenes. Unfortunately, such a method cannot be directly applied when object illumination in the considered image is oblique. The present work is aimed to propose a simple, but effective, approach for recovering 3D shape of objects starting from single side illuminated scenes i.e. for solving non-eikonal SFS problems. Tested against a set of case studies, the method proved its effectiveness. © (2014) Trans Tech Publications, Switzerland.

Keywords: Digital design | Fast marching | Intelligent manufacturing | Oblique illumination | Shape from shading

Abstract: In the last years the development of interactive Computer-based methods for building virtual and physical 2.5D models from single shaded images faced with an exponential growth. In particular, a wide range of methods based on image processing-based procedures and on Shape From Shading (SFS) can be documented. On the basis of the most favorable techniques devised in literature, the present work describes an improved interactive method capable of retrieving 2.5D models using image shading information. The pro-posed method performs a SFS-based reconstruction where (1) the overall geometry of the expected surface is first recovered and (2) the final 2.5D reconstruction is obtained by minimizing a suitable functional using the rough surface as an initialization function. The method improves previous interactive works by introducing a novel two-step rough surface recovery and a new definition of a functional to be minimized for solving the SFS problem. Tested against a set of case studies the proposed method proves to be effective in providing 2.5D models. © 2014 Science Publications.

Keywords: 2.5D model | Image processing | Interactive reconstruction | Minimization | Shape from shading

Abstract: Current CAD systems have dedicated functionalities to model weld beads, but it is often cumbersome to use these systems. This study presents a method to analyze the geometry of assemblies of B-Rep models to automatically identify possible welds among the parts using prediction rules. Adjacent faces are detected, and Boolean operators on planar loops are used to identify bead paths. Beads are then split in homogeneous portions based on the topology of the connected parts. The main goals of this study are to increase the speed of the welding definition process and to benefit applications such as the cost estimation of steelwork products. Cost estimates are based on the shape, the length and the dimension of each weld bead. Some industrial examples are presented to show the benefits in terms of time savings and accuracy to the estimation process. © 2013 © 2013 CAD Solutions, LLC.

Keywords: feature recognition | virtual prototyping of welds | weld beads identification

Abstract: The application of three-dimensional (3D) facial analysis and landmarking algorithms in the field of maxillofacial surgery and other medical applications, such as diagnosis of diseases by facial anomalies and dysmorphism, has gained a lot of attention. In a previous work, we used a geometric approach to automatically extract some 3D facial key points, called landmarks, working in the differential geometry domain, through the coefficients of fundamental forms, principal curvatures, mean and Gaussian curvatures, derivatives, shape and curvedness indexes, and tangent map. In this article we describe the extension of our previous landmarking algorithm, which is now able to extract eyebrows and mouth landmarks using both old and new meshes. The algorithm has been tested on our face database and on the public Bosphorus 3D database. We chose to work on the mouth and eyebrows as a separate study because of the role that these parts play in facial expressions. In fact, since the mouth is the part of the face that moves the most and affects mainly facial expressions, extracting mouth landmarks from various facial poses means that the newly developed algorithm is pose-independent.

Keywords: 3D face | 3D scanner | Differential geometry | Face morphology | Medical diagnosis | Soft-tissue landmarks

Abstract: In the last decades, several three-dimensional face recognition algorithms have been thought, designed, and assessed. What they have in common can be hardly said, as they differ in theoretical background, tools, and method. Here we propose a new 3D face recognition algorithm, entirely developed in Matlab ® ,whose framework totally comes from differential geometry. First, 17 soft-tissue landmarks are automatically extracted relying on geometrical properties of facial shape. We made use of derivatives, coefficients of the fundamental forms, principal, mean, and Gaussian curvatures, and shape and curvedness indexes. Then, a set of geodesic and Euclidean distances, together with nose volume and ratios between geodesic and Euclidean distances, has been computed and summed in a final score, used to compare faces. The highest contribution of this work, we believe, is that its theoretical substratum is differential geometry with its various descriptors, which is something totally new in the field.

Keywords: 3D face | Face recognition | Geodesic distance | Geometry | Landmark | Shape index

Abstract: In a recent project the authors proposed the adoption of Optimization Systems [1] as a bridging element between Computer-Aided Innovation (CAI) and PLM to identify geometrical contradictions [2], a particular case of the TRIZ physical contradiction [3]. A further development of the research has revealed that the solutions obtained from several topological optimizations can be considered as elementary customized modeling features for a specific design task. The topology overcoming the arising geometrical contradiction can be obtained through a manipulation of the density distributions constituting the conflicting pair. Already two strategies of density combination have been identified as capable to solve geometrical contradictions.

Keywords: Computer-aided conceptual design | Computer-aided innovation | Embodiment design | TRIZ

Abstract: The challenge of reducing designing time for new mechanical assemblies, especially in the context of large companies, encourages the use of methods and tools aimed to support designing activities and to re-use the company know-how. Furthermore, the design choices must be rapidly check to avoid errors that could cause delay or expensive re-designing. In such a context, the graph theory and related algorithms could be used to define a transfer function, easily to implement, that governs a software tool able to support the designing activities. Therefore, the paper presents a designing approach, based on the graph theory, aimed to generate the geometric modeling of mechanical assemblies. The approach and the software tool are useful both for designer and companies that want to customize and improve such activities. Finally, the paper shows the case study related to the design of a transversal manual gearbox and the generation of a GUI, developed in Mat LAB® environment, to validate the approach.

Keywords: CAD modeling | Digital pattern | Graph theory | Graphical user interfaces | Mechanical design

Abstract: This work is part a new design platform for lower limb prosthesis centered on the patient's digital model and based on the integrated use of virtual prototyping tools. In particular, 3D detailed model of residual limb, that includes not only the external skin but also bones and soft tissues, is needed for socket design and finite element analysis to study the socket-residual limb interaction. In this paper, we present a procedure for 3D automatic reconstruction of the residual starting from MRI images. The output is a 3D geometric model, in a neutral format (IGES), which permits CAD information exchange among the modules composing the design platform. The reconstruction procedure consists of three different phases: image pre-processing, voxel segmentation, 3D models generation. Results have been considered promising and future activities to enhance the algorithm performance have been planned. © 2013 Springer-Verlag.

Keywords: 3D automatic reconstruction | Lower limb prosthesis design | MRI | segmentation

Abstract: This paper concerns a research project that aims at developing an innovative platform to design lower limb prosthesis. The platform is centered on the virtual model of the amputee and is based on a computer-aided and knowledge-guided approach. In particular, the paper focuses on the module, named Socket Modeling Assistant-SMA, conceived to design the socket, the most critical component of the whole prosthesis. The underlining idea is to experiment low-cost devices, such the Leap Motion, to manipulate the 3D virtual model of the socket using hands as traditional done by the prosthetist. The goal is to make available a modeling tool that permits to replicate/emulate manual operations usually performed by the prosthetist during the traditional development process. First, we first describe the traditional socket development process; then the SMA software architecture and the guidelines used to develop the interaction algorithms (integrated within SMA) that exploit the Leap Motion and Falcon devices. Finally preliminary tests and results will be illustrated. © 2013 ACM.

Keywords: 3D modeling | hand tracking | haptic interaction | lower limb prosthesis

Abstract: The paper aims at exploring the opportunities for improving the Human Computer Interaction (HCI) of Computer-Aided systems for supporting designers in carrying out the early stages of the Product Development Process (PDP). In details, the authors stem from the analysis of the latest advancements and issues in the field of Question and Answer techniques, which they have already implemented in algorithms for supporting the analysis of inventive problems. According to the analysis, they identify two basic directions to improve the HCI in such systems. Literature evidences concerning the different approach of designers according to their experience point out the need of producing more flexible systems, tailored for both skilled individuals and novices. Moreover, the need emerges to both foster creativity with meaningful stimuli and introducing pictorial communication within a dialogue flow, so as to follow the common cognitive path emerged by the analysis of design protocols. The discussion shows that the combination of textual and graphical interactions is crucial to support the cognitive processes in design. Such blend allows to introduce stimuli viable to reduce design fixation and psychological inertia, that affect negatively the outcome of the idea generation stage. © 2013 CAD Solutions, LLC.

Keywords: Cognition | Computer-aided innovation | Emotion | Engineering design | HCI

Abstract: Today, the tests of a new product in its conceptual and design stage can be performed by using digital models owning various levels of complexity. The level of complexity depends on the nature and on the accuracy of the tests that have to be performed. Besides, the tests can involve or not the interaction with humans. Particularly, this second aspect must be taken into account when developing the simulation model. In fact, this introduces a different kind of complexity with respect to simulations where humans are not involved. Simulation models used for numerical analyses of the behavior of the product (such as Finite Element Analysis, multi- body analysis, etc.) are typically named Digital Mock- Ups. Instead, simulations that are interactive in their nature, requiring humans- in- the- loop, are named interactive Virtual Prototypes. They cannot be intended as a simple upgrade of a CAD model of a product, but they are instead a combination of functional models, mapped into sensorial terms and then accessed through multisensory and multimodal interfaces. In this paper, the validity of this concept is demonstrated through some case studies where interactive Virtual Prototypes are used to substitute the corresponding physical ones during activities concerning the product conceptualization and design. © 2013 CAD Solutions, LLC.

Keywords: CAD modeling | Mixed prototyping | Simulations | Virtual prototyping

Abstract: The CoMAS project aims to develop new methodologies and tools for the restoration and conservation of submerged archaeological artefacts. One of the project goals is to study the cleaning operations that are intended to remove the living organisms (algae, sponges, molluscs, etc.). These organisms cause severe deteriorations of the artefacts and their removal is crucial for the subsequent phases of consolidation and protection. In particular, the Unit of Underwater Archaeology of the Istituto Superiore per la Conservazione ed il Restauro is experimenting and comparing different cleaning techniques and tools developed in the context of the CoMAS project. This comparison requires also a precise documentation of the test cases and a quantitative measurement of the effectiveness of the cleaning procedures. This paper describes the process that has been defined in order to document and monitor the results obtained through different cleaning experiments, conducted with different tools and utensils over various types of surfaces (marble, bricks, mortar, etc.) affected by several types of biological colonization. The process includes: 1) the 3D mapping of the experimental site; 2) the planning of the tests and the choice of the areas to be cleaned; 3) the 3D reconstruction of the selected areas; 4) the execution of cleaning operations; 5) the 3D acquisition of the cleaned areas; 6) the comparison of the 3D model of the areas before and after the cleaning; 7) the analysis of the data about the cleaning effectiveness. This process has been implemented during an experimentation carried out in the "Villa dei Pisoni", located within the underwater archaeological site of Baia near Naples. © 2013 IEEE.

Keywords: 3D Reconstruction | Archaeology | Restoration | Underwater

Abstract: In some application fields, such as underwater archaeology or marine biology, there is the need to collect three-dimensional, close-range data from objects that cannot be removed from their site. In particular, 3D imaging techniques are widely employed for close-range acquisitions in underwater environment. In this work we have compared in water two 3D imaging techniques based on active and passive approaches, respectively, and whole-field acquisition. The comparison is performed under poor visibility conditions, produced in the laboratory by suspending different quantities of clay in a water tank. For a fair comparison, a stereo configuration has been adopted for both the techniques, using the same setup, working distance, calibration, and objects. At the moment, the proposed setup is not suitable for real world applications, but it allowed us to conduct a preliminary analysis on the performances of the two techniques and to understand their capability to acquire 3D points in presence of turbidity. The performances have been evaluated in terms of accuracy and density of the acquired 3D points. Our results can be used as a reference for further comparisons in the analysis of other 3D techniques and algorithms. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Keywords: 3D reconstruction | Active and passive 3D techniques | Underwater imaging

Abstract: Generally a part of electric vehicle diffusion is still based on marketing of cars and vans suitable for specific use like work vehicles. A flexible design methodology is required to support rapid prototyping and product customization in the market of tailored EV/PHEV. The research focuses the cooling simulation for a PHEV Li-Ion battery. The thermal analysis is based on the physical parameters of the single cell and on the experimental data. The proposed methodology concerns firstly an analytical approach which evaluates the average heat generated by a single cell during working condition. Then the proposed virtual prototyping analysis has been divided into two levels: the thermal simulation of one cell, and the CFD analysis of a battery module. This workflow has been applied to support the design of a battery pack for a prototypal ecological hybrid vehicle. That test case vehicle is a small van, used for the curbside collection, which has in parallel an internal combustion engine and an electric motor supplied by a LFP battery with small cylindrical cells. The analysis concerns one of the four module which constitutes the whole battery pack. The virtual model has been parameterized and the behavior of air cooling system has been evaluated through virtual tools.

Keywords: Cooling | Lithium battery | Modeling | PHEV | Simulation

Abstract: A niche of the electric vehicle market is the electric retrofit of existing vehicles. These updates replace internal combustion engines with high efficiency electric motors and high capacity Li-ion batteries. This market is dominated by mostly small and medium size enterprises that provide tailored solutions to customers. These companies seek to reduce their costs and lead times by using virtual prototyping tools and methods in the main design processes. In this context, our work defines a design methodology to support designers in the definition of cooling systems. As a test case, we analyzed the electric retrofit of a small electric car with a lead-acid battery that was updated to Li-ion technology. We focused on a simulation of the cooling of the battery using a thermal analysis based on the physical parameters of the cell and test bench results. The issue is the evaluation of the heat generated by the electrochemical reactions of lithium ion battery cells. A representative battery module was simulated following the methodological approach. The virtual prototyping analysis was divided into two levels: the thermal simulation of a single cell, and the computational fluid dynamics (CFD) analysis of a battery module composed of LiFePO4 prismatic cells. The geometric and fluid dynamic parameters were investigated with a CFD solver to study the cooling performance. A cooling system configuration was proposed and analyzed using the virtual prototyping tools. © 2013 IEEE.

Keywords: FEV | Lithium-ion battery | Modeling | Simulation

Abstract: A method for computing lines of curvature and umbilical points is proposed. These properties, derived for NURBS surfaces, are useful in shape modeling for both aesthetic and functional characteristics evaluation. Moreover, the application to the ship-hull design and to the progressive additional lens design, of umbilics and lines of curvature are investigated. © (2013) Trans Tech Publications, Switzerland.

Keywords: Computer aided design | Curvature | Differential geometry | Freeform surfaces | Lines of curvature | Principal direction | Progressive addition lens | Sculptured surfaces | Shape interrogation | Shipbuilding | Umbilical points

Abstract: In this paper we report the application of CAD/CAM based technologies for the innovative development of customized surgical devices to assist the mandibular rehabilitation in both primary surgery (resection and reconstruction) and secondary surgery (only reconstruction). Design and manufacturing of such customized surgical device are conducted according to the virtual pre-operative planning of the surgeon and with the aim to transferring this planning into the operating theatre. In the case of primary surgery, a cutting guide is developed to assist the resection step while a bone plate is developed to assist the reconstruction step. Instead, in the case of secondary surgery, in addition to the bone plate to support the reconstruction, also a repositioning guide is designed to bring back to the original position the resected stumps according to the original shape of the mandible. Finally, the components of the surgical devices are manufactured by DMLS in alloys suitable for biomedical applications. © 2012 Springer-Verlag France.

Keywords: 3D Reconstruction | Computed tomography | Computer aided design | Direct metal laser sintering | Rapid prototyping

Abstract: Purpose - The aim of this work is the development of a procedure able to model the highly irregular cellular structure of metallic foams on the basis of information obtained by X-ray tomographic analysis. Design/methodology/approach - The geometric modelling is based on the feature "pore" characterized by an ellipsoidal shape. The data for the geometric parameters of the instances are obtained with a methodology which is driven by the pore volume distribution curve. This curve shows how much the cells, whose diameter belongs to a given dimensional range, contribute to the reduction of the total volume. Findings - The presented methodology has been implemented into a CAD tool consisting of a Matlab routine identifying the instances of the feature "pore" and a CATIA's macro modelling the closed cells foam. Originality/value - The presented methodology allows to obtain in an automatic way the CAD model of the complex structure of closed cell aluminium foam approximating by considerable accuracy both the density and the volume distribution of the real foams. Copyright © 2013 Emerald Group Publishing Limited. All rights reserved.

Keywords: Aluminium foam | CAD modelling | Computer aided design | Foams | Microstructural model | OBB overlapping | X-ray tomography

Abstract: The contribution regards the surveying of two statues of famous contemporary sculptors that have been placed in the central zone of Cosenza, which has been transformed in an open air museum. To realize a 3-D representation of the museum, different methodologies have been used, based on classical surveying (total stations and GNSS), image data and range data. The increasing performances of the new models of Time Of Flight (T.O.F.) laser scanners allow to build accurate models also for medium-size objects; on the other hand, the recent techniques of 3D modeling enable the processing of large amount of data and the effective removal of noises. Thus, if an extreme accuracy is not required, one can think to use the T.O.F. laser scanner, also for the surveying of statues. For the acquisition of the surfaces of the statues, two different types of laser scanning have been used: the Leica Scan StationC10, based on Time Of Flight, and the Minolta VIVID 300 triangulation scanner. In the paper, the comparison between the results obtained by using the different techniques is described.

Keywords: 3D modelling | Augmented reality | City model | Cultural heritage | Laser scanning | Multiresolution | Representation

Abstract: The interaction metaphor, based on mouse, monitor and keyboard, presents evident limits in the engineering design review activities, when real and virtual models must be explored and compared, and also in "outside-the-office" environments, where the desk is not available. The presented research aims to explore a new generation of gesture-based interfaces, called "natural interfaces", which promise an intuitive control using free hands and without the desk support. We present a novel natural design review workspace which acquires user motion using a combination of video and depth cameras and visualizes the CAD models using monitor-based augmented reality. We implemented a bimanual egocentric pointer paradigm by a virtual active surface in front of the user. We used a XML configurable approach to explore bimanual gesture commands to browse, select, dis/assembly and explode 3D complex models imported in standard STEP format. Our experiments demonstrated that the virtual active surface is able to effectively trigger a set of CAD specific commands and to improve technical navigation in non-desktop environments: e.g. shop floor maintenance, on site quality control, etc. We evaluated the feasibility and robustness of the interface and reported a high degree of acceptance from the users who preferred the presented interface to a unconstrained 3D manipulation. © 2012 Springer-Verlag France.

Keywords: 3D manipulation | Augmented reality | CAD | Depth camera | Human computer interfaces | Natural interfaces

Abstract: This paper is an integration of a method which intends to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by two orders of magnitude. It is then possible to further optimize the geometry of the components even without supercomputers. In this paper, the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume, a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid, since temperatures vary slowly when compared to pressure (load). In fact, pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the costeffectiveness of this approach. © 2013 Pushpa Publishing House, Allahabad, India.

Keywords: CAD | FEA.Communicated by Hung-Wei Wu | Geometry | Optimization | Simulation

Abstract: Minimisation techniques are commonly adopted methodologies for retrieving a 3D surface starting from its shaded representation (image), i.e., for solving the widely known shape from shading (SFS) problem. Unfortunately, depending on the imaged object to be reconstructed, retrieved surfaces often results to be completely different from the expected ones. In recent years, a number of interactive methods have been explored with the aim of improving surface reconstruction; however, since most of these methods require user interaction performed on a tentative reconstructed surface which often is significantly different from the desired one, it is advisable to increase the quality of the surface, to be further processed, as much as possible. Inspired by such techniques, the present work describes a new method for interactive retrieving of shaded object surface. The proposed approach is meant to recover the expected surface by using easy-to-set boundary conditions, so that the human-computer interaction primarily takes place prior to the surface retrieval. The method, tested on a set of case studies, proves to be effective in achieving sufficiently accurate reconstruction of scenes with both front and side illumination. © 2013 Inderscience Enterprises Ltd.

Keywords: Boundary conditions | Computational vision | Human-computer interaction | Minimisation techniques | SFS | Shape from shading

Abstract: Industrial esthetic designers typically produce hand-drawn sketches in the form of orthographic projections. A subsequent translation from 2D-drawings to 3D-models is usually necessary. This involves a considerably time consuming process, so that some automation is advisable. Common approaches to this "reconstruction problem" start directly from "exact" 2D vector representations or try to vectorize 2D raster images prior to the reconstruction phase. These approaches, however, typically fail to deal with free form geometries like the ones commonly found in esthetic industrial design. This work presents a new methodology suitable for free form geometries, comprising the generation and processing of a 3D voxel image obtained from a hand drawing, the creation of a set of 3D curves fitting the voxel image and the automatic generation of surface patches on the resulting curve network. Several case studies are also presented in order to emphasize and discuss strengths and weaknesses of the proposed method. © 2013 Elsevier B.V. All rights reserved.

Keywords: 3D geometry fitting | 3D reconstruction | Industrial design | Orthographic views | Voxel imaging

Abstract: Face study and description through landmarks is a key activity in many fields, in particular the medical one for both corrective and esthetic surgery purposes. In a previous work, we used a geometric approach to automatically extract landmarks working in the Differential Geometry domain, through the coefficients of the Fundamental Forms, the Principal Curvatures, Mean and Gaussian Curvatures, derivatives, and Shape and Curvedness Indexes. In this paper we describe the improvements made to our previously developed algorithm by using a new parameterization of the mesh, new geometrical descriptors, and new conditions. © 2013 Elsevier B.V. All rights reserved.

Keywords: 3D face | 3D scanner | Differential Geometry | Face morphology | Soft-tissue landmark extraction

Abstract: In this work it is proposed an integrated methodology for the functional design and simulation of removable complete dentures. This methodology develops in four phases: virtual and physical prototyping, contact forces and areas analysis and functional optimization of teeth and arches geometry. A virtual environment for the modeling of the prosthesis (NM-Tooth) was developed: it includes a database of 3D CAD models of artificial teeth and allows to simulate the fabrication techniques used in dentistry. In particular, it is possible to create a full denture virtual model by a semi-automatic procedure, where a preliminary occlusal configuration is set up. By using rapid-prototyping techniques, a physical model of the prosthesis is manufactured which is utilized for the experimental, in vitro, analysis. The analysis phase includes the study of the occlusion forces in relation to the identification of contact areas; a multi-axial force measuring system allows the detection of forces acting on the physical model. Simultaneously, with a reverse engineering procedure, the relevant contact areas in the virtual model are related with the load configuration. According to the experimental output, it is possible to modify the preliminary geometry both of the arches and of the individual tooth. This integrated methodology is an original instrument to study the dental prosthesis and acquire information for its functional improvement. © 2012 Springer-Verlag France.

Keywords: Bite force | CAD modeling | Complete dentures | Contact analysis | Occlusion simulation | Virtual dentistry

Abstract: In a recent project the authors have developed an approach to assist the identification of the optimal topology of a technical system, capable of overcoming geometrical contradictions that arise from conflicting design requirements. The method is based on the hybridization of partial solutions obtained from mono-objective topology optimization tasks. In order to investigate efficiency, effectiveness and potentialities of the developed hybridization algorithm, a comparison among the proposed approach and traditional topology optimization techniques such as Genetic Algorithms (GAs) and gradient-based methods is presented here. The benchmark has been performed by applying the hybridization algorithm to several case studies of multi-objective optimization problems available in literature. The obtained results demonstrate that the proposed approach is definitely less expensive in terms of computational requirements, than the conventional application of GAs to topology optimization tasks, still keeping the same effectiveness in terms of searching the global optimum solution. Moreover, the comparison among the hybridized solutions and the solutions obtained through GAs and gradient-based optimization methods, shows that the proposed algorithm often leads to very different topologies having better performances. © 2012 Springer-Verlag London Limited.

Keywords: Computer-aided conceptual design | Computer-aided innovation | Embodiment design | Genetic algorithms | Topological optimization

Abstract: Design and manufacturing of socket are difficult activities due to the requirements that this component has to fulfill. Digital models and virtual prototyping techniques have been integrated in the socket development process trying to attain radical improvements of outcomes. However, although these tools allow to decrease the use of physical prototypes and experimental tests on patient, socket shape optimization results still insufficiently supported. In this regard, the adoption of design optimization techniques represents an opportunity to address the recalled problem. Design Optimization is rather common in several engineering fields and Shape Optimization has been widely adopted as useful tool to assist designers in searching for optimal solutions dedicated to prosthetic systems. Starting from these premises, the paper describes an approach to design socket prosthesis, which is based on Shape Optimization. The functional and ergonomic requirements of socket are analyzed and subsequently translated into optimization drivers. Moreover, implementation and integration issues of the proposed approach within the socket development process are investigated. Eventually, an application to a case study is presented aimed at preliminarily verifying potentialities and applicability. The outcomes obtained from this experience are encouraging and suggest to deepen the investigation. © 2013 CAD Solutions, LLC.

Keywords: CAD | CAE | Design | Prosthesis socket | Shape optimization

Abstract: A diagnostic engine for supporting physicians in analyzing symptoms and anamnesis of patients is proposed. The system uses fuzzy logic as the picklock to overcome difficulties typically encountered when dealing with a computer aided model for medical diagnosis, since the large number of parameters to be taken into account. The model in its current formulation allows physicians to have immediate diagnostic hypotheses considering patient's anamnesis, symptoms, drug administered and previously formulated diagnoses, simultaneously accessing available databases and suggesting new diagnostic examinations. An auto-adaptative fuzzy logic approach can be easily implemented, that could allow the model to progressively learn from each formulated diagnosis. © 2013 IFMBE.

Keywords: computerized diagnosis | fuzzy logic | Medical diagnosis | modeling

Abstract: The creation of three-dimensional virtual models by optical technologies typically involve uncontrolled metric errors, in particular, when small high-resolution 3-D imaging systems are used to reconstruct a large object. Within Cultural Heritage, the problem of metric accuracy is a major issue and no methods are currently available for controlling and enhancing it. This paper presents a methodology based on the integration of a 3D range camera system with an optical tracking technique. The basic idea is the generation of a global coordinate system determined by the optical tracker, which controls the rigid motions of the 3D range camera system during multi-scan processes. The tracking process is based on measuring the spatial coordinates of reference markers located onto the range camera. The metric reliability of the 3D model reconstruction is guaranteed to a known acceptable level. Experimental results on a Statue of Hope located at the English Cemetery in Florence, are also reported. © 2012 IEEE.

Keywords: 3D reconstruction | Cultural Heritage | optical tecquiques

Abstract: Recent advances in 3D imaging techniques have provided flexible tools for clinical assessments within many medical fields. In the field of orthodontic and orthognathic surgery, the reliable creation of 3D anatomical models can assist clinicians for both diagnosis and treatment planning. In particular, the accurate integration between facial soft tissue, facial skeleton and dentition (maxillofacial triad) provides clinicians with a complete model for virtual 3D treatment planning. However, none of the existing imaging technologies is able to simultaneously capture the complete triad with the optimal resolution and accuracy. For this reason, a "model fusion" process must be carried out in order to integrate 3D models obtained using different imaging techniques. This paper aims at introducing a procedure to create accurate maxillofacial triad models by guiding the fusion of multi-modal 3D imaging techniques. The methodology is based on integrating a structured light optical scanner with Cone-Beam Computed Tomography (CBCT) data processing in order to capture the different tissue groups composing the maxillofacial triad. The generated models represent an all-embracing virtual workbench for orthodontists in the treatment planning of malocclusion problems and for surgeons in the preoperative prediction of surgical outcomes. © 2012 IEEE.

Keywords: 3D image fusion processes | 3D reconstruction | maxillofacial model

Abstract: The paper presents the research activity developed by the authors in the field of computer-aided inventive problem solving: an original model and a dialogue-based software application have been developed by integrating the logic of ARIZ (Algorithm for the Inventive Problem Solving) with some OTSM-TRIZ (General Theory of Powerful Thinking) models in order to guide a user also with no TRIZ education to the analysis of inventive problems. The paper demonstrates that through a dialogue-based interaction it is possible to guide the user towards a proper formulation of the problem statement, which is an essential step of any conceptual design activity. The proposed software system, although still at a prototype stage, has been tested with students at Politecnico di Milano and at the University of Florence. The paper details the structure of the algorithm and the results of the first validation activity; then, it discusses about the possibility to integrate the proposed approach into a new generation of CAD systems. © 2011 Elsevier Ltd. All rights reserved.

Keywords: Computer-Aided Innovation | Conceptual design | Dialogue-based system | OTSM-TRIZ | Problem solving

Abstract: The diagnostic analysis of decay processes on small specimens is gaining importance in the restoration and maintenance of archeological finds. In this context, the 3D reconstruction is very useful for the study and identification of the different types of decay. In this paper we present the analysis conducted on two small specimens taken from an ancient underwater pavement, using a new technique for the 3D reconstruction of small sized objects based on a multi-view passive stereo technique applied on a sequence of macro images. In order to overcome the problems related to the use of macro lenses, such as the very small depth of field and the loss of sharpness due to diffraction, each image of the sequence is obtained by merging a stack of images acquired at different focus planes by the means of an image fusion algorithm. The experimentation involves a series of preliminary laboratory tests in which we validate the system accuracy and the 3D reconstruction of specimens taken from a marble pavement located in the underwater archeological site park of Baiae (Naples, Italy). The results show that with our approach it is possible to obtain high quality textured 3D models of objects with dimensions ranging from few millimeters to few centimeters, which can be usable both for interactive measurements and virtual presentations. © 2012 IEEE.

Keywords: 3D reconstruction | Cultural Heritage | Image Fusion | Macro Lens | Small Objects

Abstract: This paper introduces a method to simplify a non linear problem in order to use linear finite element analysis. This approach improves calculation time by two orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, stress magnitude and stress gradient. This assumption is valid since temperatures varies slowly when compared to pressure (load & stress). In fact pressure propagates with the speed of sound. The method is validated by direct comparison with non linear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approach.

Keywords: CAD | FEA | Geometry | Optimization | Simulation

Abstract: Recently, 3D landmark extraction has been widely researched and experimented in medical field, for both corrective and aesthetic purposes. Automation of these procedures on three-dimensional face renderings is something desirable for the specialists who work in this field. In this work we propose a new method for accurate landmark localization on facial scans. The method relies on geometrical descriptors, such as curvatures and Shape Index, for computing candidate and initial points, and on a statistical model based on Procrustes Analysis and Principal Component Analysis, which is fitted to candidate points, for extracting the final landmarks. The elaborated method is independent on face pose. © 2012 Elsevier Ireland Ltd.

Keywords: 3D face | Differential Geometry | Landmark extraction | PCA | Procrustes Analysis

Abstract: The face is one of the most important parts of the human anatomy, and its study is very important, especially for developing automatic public security recognition strategies. In order to support this field, it is necessary to find a formal way of converting what the human eyes normally do in recognizing one person from another by extracting implicitly some morphological features. Since human recognition happens through an automatic "authentication" of facial shape and features, this study should be undertaken in the geometrical domain. The technical literature shows many parameters that could be adopted for finding a solution to this problem, but at present there is no evidence of a reliable solution. For this reason, this work, analysing strengths and constraints of what is available in the geometrical domain, provides the first guideline for supporting the development of an automatic face recognition approach. Starting from differential geometry, such as the coefficients of the fundamental forms, the principal curvatures, mean and Gaussian curvatures, the derivatives and the shape and curvedness indices introduced by Koenderink and VanDoorn, this paper, working on a consistent set of case studies, analyses the geometrical descriptors' performances in the three-dimensional facial study by the use of a set of indicators (similarity between different faces, sensitivity to noise, etc.). This is a preliminary study for analysing the behaviours of these descriptors on faces. It may be used as a guideline or a theoretical framework for researchers studying face shape or for face recognition applications. © 2012 Elsevier B.V. All rights reserved.

Keywords: 3D scanners | Differential geometry | Face morphometry | Geometrical descriptors | Geometrical human modelling

Abstract: Purpose - The purpose of this paper is to define an approach to extract the liaison graph from a 3D CAD model and analyze a method to find at least a feasible assembly sequence for the product. The method could be useful to search the optimal sequence of assembling for a product, by comparing different sequences extracted in automatic mode from a 3D CAD model. Design/methodology/ approach - The method proposed analyzes the liaison graph extracted, in order to obtain the possible assembly sequences for the product under study. The extraction of the sequences is based on some attributes and parameters of the graph. Findings - By means of the method proposed it is possible to obtain in automatic mode the liaison graph of an assembly 3D CAD model. Moreover, the study of the graph obtained allows the definition of all the assembly sequences for the product. Finally, it is possible to analyse the sequences found to select the optimal sequence. Research limitations/implications - The major limitation of the approach is, actually, the great number of impossible sequences that are extracted. For this, a little intervention by the user is required. Practical implications - The application of the method allows the manufacturer to analyze and study the optimal assembly sequence without the direct use of a CAD system. The approach could be used at the early stage of the design process and by means of the database of the PDM/PLM systems. Originality/value - The approach proposed in the paper is an original method to extract a liaison graph from a 3D CAD model. The approach to extract the assembly sequences was compared with other methods and good results have been obtained. © Emerald Group Publishing Limited.

Keywords: Assembly | Assembly modelling | Assembly sequences planning | Modelling | Process planning

Abstract: This paper deals with the investigation of the stability and the accuracy of the most important methods to estimate the parameters that are involved in the shape recognition process of tessellated surfaces. For this purpose, four approaches to estimate the differential geometric properties of tessellated surfaces are systematically examined (namely, simple and extended quadric fitting methods, Rusinkiewicz's method and Meyer discrete method). A set of test cases has been designed in order to investigate the sensitivity of those methods to factors such as noise in point location, surface typology (chosen between those types that usually define the boundary of mechanical parts such as: planes, cylinders, spheres, cones and tori), mesh resolution and mesh regularity. Based on the results obtained, some criticism of the analyzed methods is made and some guidelines are provided in order to choose the most robust and reliable method in relation to the surface typology, quality of the mesh and noise in point location. © 2011 CAD Solutions, LLC.

Keywords: Curvature estimation | Shape recognition | Triangular meshes

Abstract: Current research on underwater 3D imaging methods is mainly addressing long range applications like seafloor mapping or surveys of archeological sites and shipwrecks. Recently, there is an increasing need for more accessible and precise close-range 3D acquisition technologies in some application fields like, for example, monitoring the growth of coral reefs or reconstructing underwater archaeological pieces that in most cases cannot be recovered from the seabed. This paper presents the first results of a research project that aims to investigate the possibility of using active optical techniques for the whole-field 3D reconstructions in an underwater environment. In this work we have tested an optical technique, frequently used for in air acquisition, based on the projection of structured lighting patterns acquired by a stereo vision system. We describe the experimental setup used for the underwater tests, which were conducted in a water tank with different turbidity conditions. The tests have evidenced that the quality of 3D reconstruction is acceptable even with high turbidity values, despite the heavy presence of scattering and absorption effects. © 2011 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

Keywords: 3D reconstruction | Imaging in turbid medium | Photogrammetry | Structured light | Underwater imaging

Abstract: 3D CAD techniques represent today a crucial tool in almost all the design fields. Nevertheless, due to a number of well known reasons, multi orthographic view drawings are still widely used; accordingly, the conversion of 2D drawings into 3D CAD models (known in the scientific literature as the "reconstruction problem") is still a key issue. During the last decades a number of works, dealing with the reconstruction problem, have been proposed. On the basis of these works, the authors have developed and implemented an automatic procedure that allows the reconstruction of 3D polyhedral models. The reconstruction procedure involves a number of software routines; by means of them, an initial 2D DXF file is processed and a set of 3D solutions, consistent with the initial drawing, is extracted. The obtained 3D models are subsequently output according to the most common 3D exchange formats (e.g. IGES, STEP, Parasolid, etc.). The proposed procedure and its implementation have been developed in order to achieve two main goals: to introduce researchers into the "reconstruction problem" and to create a common basis in order to methodologically compare different procedures dealing with the "reconstruction problem" itself.

Keywords: 3D reconstruction | CAD | Computational geometry | Engineering drawings | Orthographic projections | Pseudo-wireframe

Abstract: The paper illustrates an original model and a dialogue-based software application that have been developed by integrating the logic of ARIZ with some OTSM-TRIZ models, in order to guide a user, also with no TRIZ background, to the analysis of inventive problems. The dialogue-based procedure brings to the construction of a model of the inventive problem, which is used both to trigger new solutions by highlighting different solving perspectives and to start an automatic knowledge search within technical and scientific information. The prototype system has been tested with students at Politecnico di Milano and at the University of Florence. The paper details the structure of the algorithm and the results of the first validation activity. © 2011 IFIP International Federation for Information Processing.

Keywords: Computer-Aided Innovation | conceptual design | dialogue-based system | OTSM-TRIZ | problem solving

Abstract: Among the different aims and scopes of Computer-Aided Innovation (CAI) systems a relevant topic is the support of inventive problem solving tasks. The paper presents the research activity developed by the authors in this domain, encompassing the review of the distinctive features of problems encountered by designers and the common approaches employed to overcome them. A further thread of the investigation carried out in this paper concerns the limitations of computer-based approaches exploiting acknowledged models for problem solving. Downstream of the performed analysis the authors highlight the requirements that a novel CAI application should fulfil, supporting the opportunities for building a dialogue-based system. © 2011 IFIP International Federation for Information Processing.

Keywords: Computer-Aided Innovation | conceptual design | dialogue-based system | inventive problem solving

Abstract: This paper aims at improving the efficiency of an inventive problem solving process for complex systems, by reducing the iterations due to the emergence of new problems caused by the implementation of the identified solution. The proposed algorithm guides the problem solver in choosing the most important contradiction to be faced with ARIZ85-C and provides further instructions about the best approach to be followed. Such purpose is achieved by organizing the characteristic parameters of a Technical System according to a specific metric, which allows both the construction of a Network of Contradictions and the definition of criteria for identifying priorities. An exemplary application of the proposed method has been carried out in the field of exhaust noise in 4-stroke engines. © 2011 Published by Elsevier Ltd.

Keywords: ARIZ | Computer-aided innovation | Network of contradictions | Problem complexity

Abstract: CAD-integrated LCA tools are developed in order to support SLCA (Simplified Life Cycle Assessment) method and they could be used as eco-design tools in the design phase. Nevertheless they are still a long way from being accurate and properly usable. The present work aims at demonstrating this assumption in concrete terms by focusing the attention on the mechanical field. A comparison analysis between CAD-integrated LCA tools and dedicated LCA tools has been proposed in order to determine the main causes of error and to propose guidelines for improvement. An approach based on these guidelines is presented and preliminarily evaluated.

Keywords: CAD | Eco-design | Life Cycle Assessment

Abstract: Nowadays three-dimensional Computer Aided modeling is of out-standing importance in the mechanical design process since it impacts on several issues like visualization, simulation, machining, etc. Anyway, multi orthographic view engineering drawings have been widely used up to latest decade and still are, so they play an essential role in traditional engineering. The conversion from 2D drawings to 3D CAD models is still a key task in a wide range of applications. In order to cope with this issue a number of works have been proposed in the last decades, providing a series of methodologies for solving the reconstruction prob-lem. On the basis of such methodologies the main aim of the present paper is to suggest a comprehensive, orderly, unambiguous and automatic procedure meant to help researchers and practitioners who want to deal with the reconstruction problem. The procedure, by using an appropriate formal mathematic language, systematize and integrates some of the methods proposed so far. © 2011 Heldermann Verlag.

Keywords: 3D reconstruction | Computational geometry | Computer aided design | Engineering drawings | Or-thographic projections | Pseudo-wireframe

Abstract: Computer Aided Engineering (CAE) techniques provide effective solutions for automating the whole product development chain process. Designers, engineers, manufacturing professionals and researchers can now leverage solid modeling data and multi-physics analysis in ways that were inconceivable just few years ago. Among CAE techniques, Computer Aided Design (CAD) has been the most effective in providing methodologies capable of compressing product design and manufacturing cycles, assuring faster turnaround time between design and simulation and improving product quality. Designers and manufacture companies reap the rewards of 3D CAD modelling; as a consequence, research is unceasingly stimulated to look forward. On one hand, research aims to improve capabilities of existing CAD methods and tools; on the other hand novel approaches are extensively investigated with the ambition of carrying out innovative CAD techniques capable of lighting sparking design innovation and creativity. This is particularly true for mechanical design: fast and robust 3D retrieval from 2D drawings that was considered future trend few years ago, is now a key target for commercial software houses like Dassault Systems® and Autodesk® as well as a vigorous focus from an academic outlook. Unfortunately, even if a number of works have been carried out during the last decades, these are mainly described by a conceptual point of view. To derive an orderly procedure covering the necessary steps for retrieving 3D models from mechanical drawings could provide a dramatic boost to researchers and practitioners that introduce this issue on their research. Therefore, the main aim of the present work is to carry out a systematic clear and concise step-by-step procedure for 3D retrieval starting from wireframe models. Since the intent is to afford an as clear as possible, guided, procedure for 3D reconstruction, mathematical description is limited to the simplest case of polyhedral objects. The proposed procedures, inspired by state of the art works, can be effectively contribute to speed-up the possible implementation of methodologies confronting the 3D reconstruction problem.

Keywords: 3D Retrieval | Computational geometry | Computer aided design | Mechanical drawings | Pseudo-wireframe

Abstract: Diabetes is one of the main causes that generate foot health related diseases. It impacts on a large percentage of world population and is expected to grow in next 20 years. Good footwear is fundamental for influencing foot health status in particular when foot can be subjected to many serious problems as in case of diabetic patients. This research work faces this problem by defining an approach and related computeraided echnologies in order to properly design customized shoes for people suffering from diabetes. Design rules have been fixed by formalizing knowledge that expert podiatrists use to prevent foot diseases. Studied and implemented technologiesinterest the whole footwear design process: foot scanning, foot dynamic pressure measurement, design of last, insole and outsole. This paper is focused on the description of design software system structure and related tools, and, then, it reports preliminary experimental results on 20 case studies. © 2011 CAD Solutions, LLC.

Keywords: Cad modeling | Diabetes | Footwear customization

Abstract: In the footwear industry there is growing methodological research linking advanced computer-based technologies to the traditional manufacturing process. This paper deals with the automation of shoe design phases and describes a computer aided design system that brings together theories and tools from geometric modeling, image processing, and reverse engineering. At first, the paper reviews the current technologies used for creating new shoe models. Then the paper presents an approach based on shoe 3D virtual modeling in order to overcome the traditional time-consuming manual operations. The approach is concretized into dedicated tools able to automatically perform design of the last shape model and flattening of the shoe styling curves represented in the virtual prototype. The modeling tool uses 3D geometric rules derived from the analysis of strategies adopted by skilled manual operators, while the styling curves recognition and flattening are based on specific image processing algorithms and geometrical deformation rules. Experimental results show a good compromise between quality results and modeling time. © 2011 Springer-Verlag.

Keywords: Design automation | Footwear industry | Reverse engineering | Time compression technologies

Abstract: Diabetes is one of the main causes that generate foot health related diseases. It impacts on a large percentage of world population and is expected to grow in next 20 years. Good footwear is fundamental for influencing foot health status in particular when foot can be subjected to many serious problems as in case of diabetic patients. This research work faces this problem by defining an approach and related computer-aided technologies in order to properly design customized shoes for people suffering from diabetes. Design rules have been fixed by formalizing knowledge that expert podiatrists use to prevent foot diseases. Studied and implemented technologies interest the whole footwear design process: foot scanning, foot dynamic pressure measurement, design of last, insole and outsole. This paper is focused on the description of design software system structure and related tools, and, then, it reports preliminary experimental results on 20 case studies. © 2011 CAD Solutions, LLC.

Keywords: CAD modeling | Diabetes | Footwear customization

Abstract: In this chapter the authors discuss several approaches in order to integrate computeraided engineering instruments into Augmented Reality environment. Engineers and designers often develop their creative ideas in front of a computer monitor using mouse and keyboard. Although the integration between numerical computation and graphics leads to the generation of very realistic digital mock-ups, they are still far from the real context and the user has limited interaction with them. The purpose is to illustrate how recent development in computer graphics and image processing can improve the realism and interactivity with digital mock-ups. Starting from the interactive modeling of 3d shapes, the chapter presents some examples about the integration of real-time mechanism motion simulation, structural and fluid dynamics analysis post-processing. © 2010 by Nova Science Publishers, Inc. All rights reserved.

Keywords: Augmented reality | Computer-aided design | Simulation | Virtual engineering

Abstract: Many design approaches have been developed to support the tasks involved in the Conceptual and Embodiment design phases, but their nature has led to very different paradigms. The translation of the system concept into its structure still represents a critical task, since the models adopted for conceptual design are not directly compatible with those involved in the embodiment stage. Enhancing the interoperability of these models is therefore a key issue to improve the overall efficiency of the Product Design Cycle. According to this objective, in this paper an investigation is presented, aimed at testing the integration between OTSM-TRIZ approach to concept development and DAeMON, which is an original technique for multi-objective optimization developed by the authors. The functionality of the proposed model has been verified through its application to a case study concerning the redesign of a dot printer component. The results demonstrate the potential of the integrated paradigm in guiding the designer from the identification of the right problem to solve, to the embodiment of the solution. Furthermore, such experience allowed a preliminary investigation of a set of rules for developing a new framework for innovative embodiment tasks.

Keywords: Embodiment design | Hybridization | OTSM-TRIZ | Topological optimization

Abstract: Current product lifecycle management (PLM) systems properly support the development of a product from the embodiment design stage to detail design and manufacturing phases; on the contrary, marginal support is provided to the earliest stages of conceptual design. Besides, the front end of product development is supported by an emerging technology, namely computer-aided innovation systems (CAI), which nevertheless are still poorly integrated with the following phases of the design process. The paper presents an original computer-based approach aimed at supporting embodiment design phases, which results very efficient for improving the interoperability of CAI and PLM systems and thus at extending the domain of application of these tools. The potential of the approach proposed by the authors is clarified through three exemplary case studies. © 2010 Elsevier B.V. All rights reserved.

Keywords: Computer-aided innovation | Embodiment design | Optimization systems | PLM | TRIZ

Abstract: Within the framework of the Research Project PROSIT [1] aimed at the development of an integrated product design platform capable to link Computer-Aided Innovation (CAI) with PLM/EKM systems, the authors have approached the analysis of the contradictions emerging during the design embodiment phase. In this case, since the functional architecture of the product is already fixed, design conflicts arise due to contradictory geometrical requirements. Design Optimization systems can play a relevant role for the identification of these "geometrical contradictions", even if with modified criteria of usage. The present paper first describes how Design Optimization can be adopted as a means to link CAI and PLM/EKM systems; then a detailed analysis of geometrical contradictions is reported together with the criteria proposed for their categorization. Finally, the discussion is focused on the adoption of the proposed classification of geometrical contradictions as a pointer to the most suitable inventive principles and geometrical effects to overcome the design conflicts. © 2011 Published by Elsevier Ltd.

Keywords: Computer-Aided innovation | Shape optimization | Systematic design | Topological optimization | TRIZ

Abstract: Marketing strategies are focusing on innovation as the key for being competitive; as a consequence, product development processes must be improved in order to have a link as close as possible between conceptual design and detailed design activities. Within this context, TRIZ and TRIZ-based methodologies and tools are still poorly integrated with product embodiment means: CAD/CAE systems are not suited for supporting the designer in the conceptual design phase and at the same time inventive/separation principles, standard solutions etc. can hardly be translated into a modification of a CAD model and the only opportunity is to restart the modeling process. A small consortium of Italian Universities is analyzing the opportunity to use Design Optimization tools as a means for linking Computer-Aided Innovation (CAI) tools with Product Lifecycle Management (PLM) systems: www.kaemart.it/prosit. Among the specific objectives of the project, this paper describes how to analyze TRIZ technical contradictions by means of Design Optimization tools, with the aim of translating them into physical contradictions. The suggestions provided by inventive/separation principles are therefore converted into a new Design Optimization problem for the development of a novel solution. © 2011 Published by Elsevier Ltd.

Keywords: Computer-aided innovation | Shape optimization | Systematic design | Topological optimization | TRIZ

Abstract: Model-based definition (MBD) is a new strategy of product lifecycle management (PLM) based on computer-aided design (CAD) models transition from simple gatherers of geometrical data to comprehensive sources of information for the overall product lifecycle. With MBD, most of the data related to a product are structured inside native CAD models, instead of being scattered in different forms through the PLM database. MBD aims are suppression of redundant documents and drawings, better data consistency, better product/process virtualization, and better support for all computer-aided technologies tasks under engineering and manufacturing disciplines. Developing MBD today, for a medium- to large-sized company in the automotive and aerospace sectors, deals primarily with its fundamentals: data structures. Companies need a common approach to structure data in reusable, unified forms inside native three-dimensional CAD models. For this reason, this research work has been developed by focusing the attention on a method for supporting the MBD implementation by the use of the quality function deployment approach. In order to analyze the efficacy of the proposed approach, it has been validated in the aerospace and defense domain where companies deal with complex products, characterized by a large amount of data exchange, and where collaborative design is a fundamental practice. © 2010 Springer-Verlag London Limited.

Keywords: Computer-aided design | Model-based definition | Paperless engineering | Product lifecycle management | Product virtualization

Abstract: This paper presents a methodology in which CAD, a multi-body simulator and a topological optimization tool are synergically employed in order to support the design of a suspension component. In particular, the methodology defines some guidelines and introduces two Knowledge Based interfaces able to facilitate the integration of topological optimization of the component within a standard design process. In order to illustrate this capability, the process is applied to the conceptual design of the Upright for a Formula SAE prototype. The results show that the integrated design approach can efficiently support the selection of the optimum conceptual design of a mechanical component with complex dynamic behaviour, in particular when very little previous experience on the system is available. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Integrated approach | Knowledge based engineering | Multi-body | Topological optimization

Abstract: One of the open issues in Augmented Reality (AR) applications is certainly related to interaction techniques. In these years many different solutions have been proposed with the intent of providing user interfaces that allow users to interact with the AR environment in a natural and intuitive way. Most of them have addressed the issue of representing users' hands in the AR environment. We propose the use of a commercial and low-cost wireless device to use as input device for AR. This paper describes the integration of this device into an AR application, and some preliminary tests aiming at evaluating the tracking accuracy and precision. In addition, we demonstrate the usability of our system through a preliminary testing session with users. ©2010 IEEE.

Keywords: Multimedia Information Systems|Artificial, augmented, and virtual realities|User Interfaces|Ergonomics|Input devices and strategies|Computer-Aided Engineering|CAD

Abstract: The offer of tailored products is a key factor to satisfy specific customer needs in the current competitive market. Modular products can easily support customization in a short time. Design process, in this case, can be regarded as a configuration task where solution is achieved through the combination of modules in overall product architecture. In this scenario efficient configuration design tools are evermore important. Although many tools have been already proposed in literature, they need further investigation to be applicable in real industrial practice, because of the high efforts required to implement system and the lack of flexibility in products updating. This work describes an approach to overcome drawbacks and to introduce a product independent configuration system which can be useful in designing recurrent product modules. To manage configuration from the designer perspective, the approach is based on Configurable Virtual Prototypes (CVP). In particular, the definition of geometrical models is analyzed providing a tool for eliciting and reusing knowledge introduced by parametric template CAD models. Semantic rules are used to recognize parts parameterization and assembly mating constraints. The approach is exemplified through a case study. © 2010 by ASME.

Keywords: Design automation | Modularity | Product configuration

Abstract: An efficient mechanical product design process implies the evaluation of many alternatives in a short time and rapid product changes on the basis of emerging needs. Product cost is one of the main factors in order to choose the most promising solution. Hence its accurate estimation in the design phases is fundamental. The main problem is the vast amount of knowledge that has to be managed in order to make robust evaluations. Features based 3D CAD models implicitly contain part of needed information. But such information has to be elaborated by adopting suitable rules based on manufacturing knowledge. In this context, the paper presents an approach and the related knowledge-based system able to automatically make reliable cost estimation starting from the 3D CAD model. The approach is based on the manufacturing knowledge formalization, on the geometrical and non-geometrical feature automatic recognition and, finally, on the mapping between manufacturing operations and modelling features. In order to validate the system performance case studies are reported. © 2010 Springer-Verlag London Limited.

Keywords: Cost estimation | Feature recognition | Knowledge-based systems

Abstract: A new protocol for making an immediate provisional eyeglasses-supported nasal prosthesis is presented that uses laser scanning, computer-aided design/computer-aided manufacturing procedures, and rapid prototyping techniques, reducing time and costs while increasing the quality of the final product. With this protocol, the eyeglasses were digitized, and the relative position of the nasal prosthesis was planned and evaluated in a virtual environment without any try-in appointment. This innovative method saves time, reduces costs, and restores the patient's aesthetic appearance after a disfiguration caused by ablation of the nasal pyramid better than conventional restoration methods. Moreover, the digital model of the designed nasal epithesis can be used to develop a definitive prosthesis anchored to osseointegrated craniofacial implants.

Keywords: CAD/CAM | Computer-aided design | Facial disfigurement | Facial rehabilitation | Immediate temporary prosthesis | Maxillofacial rehabilitation | Nasal prosthesis rapid prototyping | Reverse engineering | Silicone prosthesis | Virtual molding

Abstract: Ear defects in patients affected by Treacher Collins syndrome necessitate the replacement of the existing anatomic residuals of the ears with custom-made prostheses. This paper describes a multidisciplinary protocol involving both medicine and computer-aided design/computer-aided manufacturing for manufacturing ear prostheses. Using innovative prototyping technologies together with conventional silicone processing procedures, a step-by-step procedure is presented. The complete workflow includes laser scanning of the defective regions of a patient's face, the use of 3D anatomic models from an ear digital library and rapid prototyping of both substructures for bar anchoring and moulds for silicone processing. © 2010 Taylor & Francis.

Keywords: Computer-aided design | Ear prostheses | Maxillofacial rehabilitation | Rapid prototyping | Reverse engineering | Treacher Collins syndrome

Abstract: Restoration of a nasal defect after ablative surgery for squamous cell carcinoma necessitates replacing the missing volume and anchoring a prosthesis to the patient’s face. This report describes the failure of plastic reconstructive surgery after ablation of a squamous cell cancer of the nose and the esthetic and functional restoration of the patient with a nasal prosthesis. The process of making an implant-supported prosthesis using digital technology, including digitized anatomic models from a "nose library," and the rapid prototyping of the mesiostructure for bar anchorage and of the mold for silicone processing are presented. © 2010 by Quintessence Publishing Co Inc.

Keywords: Computer-aided design | Computer-assisted manufacture | Maxillofacial prosthesis | Nasal prosthesis | Rapid prototyping

Abstract: Companies applying mass customization paradigm regard the design process as a configuration task where the solution is achieved through the extraction of a new instance from a modular product structure. In this context product configuration management tools are evermore important. Although tools have been already proposed, they fail in real industrial contexts. Main causes are recognizable in high efforts in systems implementation and lack of flexibility in products updating. This research aims to develop an approach to overcome drawbacks and simplify the implementation and the use of product configuration systems also in redesign activities. The paper initially reviews existing systems in terms of design knowledge representation methods and product structure formalization techniques. Then, an approach based on Configuration Virtual Prototypes which store and manage different levels of knowledge, is presented. In particular, a framework is outlined in order to represent design data and its formalization in configuration tools. Three different domains are managed and connected via Configuration Virtual Prototypes: Product Specifications, Geometrical Data and Product Knowledge. Specifically, geometrical data aspects are analyzed in detail providing approaches for eliciting knowledge introduced by parametric template CAD models. The approach will be exemplified through a real application example where an original tool has been developed on the based of the described method. Benefits of the system will be shown and briefly discussed, in particular in terms of reachable flexibility in solutions. Copyright © by ASME.

Keywords: Design automation | Modularity | Product configuration

Abstract: A new method of reverse engineering for fast, simple and interactive acquisition and reconstruction of a virtual three-dimensional (3D) model is presented. We propose an active stereo acquisition system, which makes use of two infrared cameras and a wireless active-pen device, supported by a reconstruction method based on subdivision surfaces. In the 3D interactive hand sketching process the user draws and refines the 3D style-curves, which characterize the shape to be constructed, by simply dragging the active-pen device; then the system automatically produces a low-resolution mesh that is naturally refined through subdivision surfaces. Several examples demonstrate the ability of the proposed advanced design methodology to produce complex 3D geometric models by the interactive and iterative process that provides the user with a real-time visual feedback on the ongoing work. © 2010 Elsevier Ltd. All rights reserved.

Keywords: Computer-aided design | Interactive 3D input device | Subdivision surfaces

Abstract: In this paper, the authors discuss a methodology to enhance multibody systems simulations using Augmented Reality (AR) implementation. The AR deals with the use of live video imagery which is digitally processed and augmented by the addition of computer generated graphics. The purpose is to illustrate how recent developments in computer-aided design and augmented reality can improve the realism and interactivity when simulating the movement of digital mock-ups. The paper discusses hardware and software implementations and an overview of several illustrative examples. The basic idea is described starting from a simple simulation of a falling body subjected to gravity with the initial conditions set interactively by the user. Then, a more complex interactive simulation of the kinematics of a robot whose end-effector can be grabbed and moved by the user is presented. Finally, the real time dynamic simulation of a slider crank mechanism is discussed. The integration between AR and multibody simulation has revealed to be very useful for didactical purposes and collaborative design.

Keywords: Augmented Reality | Interactive simulation | Multibody

Abstract: In a recent project [8] the authors have developed an approach to assist the identification of the optimal topology of a technical system capable to overcome geometrical contradictions that arise from conflicting design requirements. The suggested method is based on the hybridization of partial solutions obtained from mono-objective topology optimization tasks. In order to investigate efficiency, robustness and potentialities of hybridization, a comparison among the proposed approach and the traditional Topology Optimization methods is here presented. The application of the proposed hybridization approach to several case studies of multi-objective optimization problems available in literature has been performed with the aim to evaluate the robustness of the method, through a direct benchmark between the hybridized topology and the traditional methods. The obtained results demonstrate that the proposed method is computationally definitely less expensive than the conventional application of Genetic Algorithms to topological optimization, still keeping the same robustness in terms of searching the global optimum solution. Moreover, the comparison among the hybridized solutions and the solutions obtained through traditional topology optimization methods, shows that the proposed approach often leads to very different topologies having better performance. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Computer-aided conceptual design | Computer-aided innovation | Embodiment design | Genetic algorithms | Topological optimization | TRIZ

Abstract: The paper presents a methodology aimed at the improvement of the product development cycle through the integration of Computer-Aided Innovation (CAI) with Optimization and PLM systems. The interoperability of these tools is obtained through the adoption of Optimization systems as a bridging element between CAI and PLM systems. This methodology was developed within the PROSIT project (http://www.kaemart.it/prosit). The paper describes the main issues related to the integration of these complementary instruments and the solutions proposed by the authors. More specifically, the main idea of the PROSIT project to link CAI and Optimization systems is the adoption of the latter tools not just to generate optimized solutions, but also as a design analysis tool, capable to outline critical aspects of a mechanical component in terms of conflicting design requirements or parameters. CAI systems are then applied to overcome the contradictory requirements. The second step, i.e. the integration between Optimization and PLM systems, has been obtained through the development of Knowledge-Based (KB) tools to support designer's activities. More in details, they provide means to analyze and extrapolate useful geometrical information from the results provided by the optimizer, as well as semi-automatic modelling features for some specific geometries. A detailed example related to the design of a plastic wheel for light moto-scooters clarifies the whole procedure. The paper integrates, extends and updates topics presented in Cugini et al., Barbieri et al. and Cascini et al. [U. Cugini, G. Cascini, M. Ugolotti, Enhancing interoperability in the design process-the PROSIT approach, in: Proceedings of the 2nd IFIP Working Conference on Computer-Aided Innovation, Brighton (MI), USA, October 8-9, 2007, published on Trends in Computer-Aided Innovation, Springer, ISBN 978-0-387-75455-0, pp. 189-200; L. Barbieri, F. Bruno, M. Muzzupappa, U. Cugini, Design automation tools as a support for knowledge management in topology optimization, in: Proceedings of the ASME 2008 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE 2008), Brooklyn, New York, USA, August 3-6, 2008; L. Barbieri, F. Bruno, M. Muzzupappa, U. Cugini, Guidelines for an efficient integration of topological optimization tools in the product development process, in: Third International Conference on Design Computing and Cognition, Atlanta, USA, June 23-25, 2008; G. Cascini, P. Rissone, F. Rotini, From design optimization systems to geometrical contradictions, in: Proceedings of the 7th ETRIA TRIZ Future Conference, Frankfurt, Germany, November 6-8, 2007]. © 2009 Elsevier B.V. All rights reserved.

Keywords: Computer-Aided Innovation | Knowledge-Based Engineering | Optimization systems | Product Lifecycle Management

Abstract: Virtual reality (VR), even if it does not represent any more a novel technology, is one of the most powerful tool to help designers during the development of new projects. This is proved by very numerous research activities related to this field. In this research, we have studied a new way to approach the development of a product. We present the ongoing development of a system, called VirDe, acronym of virtual design, which can allow the designers to perform the whole design process, from the modelling phase to the finite element method (FEM) simulation analysis, in a virtual reality environment. This new method allows remarkable time and money saving in the overall product design process, but the most important contribution of VirDe is that, as far as we concerned, there is no known similar approach which has been studying the simultaneous combination of CAD, FEM and virtual environment (VE). © Springer Verlag France 2008.

Keywords: 3Dinput device | CAD modelling | FEM analyses | Simulation | Virtual reality

Abstract: Simulation and other computer aided tools are often used in automotive design, since the design process is strictly oriented to the optimization of the performances through an iterative synthesis and analysis cycle aimed to understand the effects of changes in the geometry and layout of the various components. The search for the optimal performances is at the moment carried out empirically by the "trial and error" approach because parameters and constraints are too many for a global optimization of the vehicle dynamics to be performed. Nevertheless it is possible to introduce in the current design process some optimization algorithms or tools that can guide the designer in the decision process. This paper presents a methodology, applied to the conceptual design of the upright for a Formula SAE prototype, in which a multi-body simulator, CAD and a topological optimization tool are sinergically employed in order to support the suspension design.

Keywords: Integrated approach | Multi-body | Topological optimization

Abstract: Measuring cylinders' out-of-roundness is still a big issue when high accuracy, high velocities or large cylinders are needed. The performance of the methods for roundness detection based on multi-probe scanning are strictly related to both the 3-D motion of the cylinders and the probes mounting configuration. Those effects are currently taken into account only in its 2D simplified form. Due to the lack of methods able to simulate 3D effects, a combined mathematical numerical method was developed. The cylinder is modelled making use of a mathematical description via Discrete Fourier Transform (DFT) of both its cross section and axis deviation. Efficient numerical simulation is employed to estimate the sensors' output taking also into account the cylinder shape effect interaction with unilateral constraints as a function of the cylinder rotation. Some simulations are carried out with the purpose of demonstrating the importance of modelling the entire 3D effects. Simulations show that an inaccuracy on 1° inclination of the probes support can result in an error of 1mm on the sensors output even considering a max amplitude of harmonics of 0.1 mm. Finally a reconstruction using the three point method based on FFT is applied to simulated measures showing that the 3D effects can increase the fluctuating part of the radius reconstruction error by 100 times.

Keywords: Cylinder | Measurement | Milling | Modelling | Roundness | Simulation

Abstract: In a recent project the authors have proposed the adoption of Optimization Systems [1] as a bridging element between Computer-Aided Innovation (CAI) and PLM to identify geometrical contradictions [2], a particular case of the TRIZ physical contradiction [3]. A further development of the research [4] has revealed that the solutions obtained from several topological optimizations can be considered as elementary customized modeling features for a specific design task. The topology overcoming the arising geometrical contradiction can be obtained through a manipulation of the density distributions constituting the conflicting pair. Already two strategies of density combination have been identified as capable to solve geometrical contradictions and several others are under extended testing. The paper illustrates the most recent results of the ongoing research mainly related to the extension of the algorithms from 2D to 3D design spaces. The whole approach is clarified by means of two detailed examples, where the proposed technique is compared with classical multi-goal optimization.

Keywords: Computer-Aided Conceptual Design | Computer-Aided Innovation | Embodiment Design | Topological optimization | TRIZ

Abstract: This paper discusses aspects related to the implementation of Design Automation applications within Small Medium Enterprises (SMEs) industrial context. It focuses the attention on some characteristics of the design process in SME context, and highlights issues of DA in relation to the characteristics previously evidenced. On this basis, it has been defined a methodology, named MEDEA (Methodology per Design Automation), to develop DA applications; it proposes a step by step roadmap and suggests methods and tools finalized to developers more skilled on products and design process than on IT technologies. Two industrial applications realized to evaluate the methodology are then presented. They are based on two different approaches: the first suitable to represent product structure and derived from Object Oriented programming and the second based on design process representation. © 2008 International Federation for Information Processing.

Keywords: Design automation | Knowledge representation | Knowledge-based engineering | PDM/PLM | SMEs

Abstract: The efficacy of virtual reality (VR) as a design support technique is widely recognised by industries. However, the efficiency of the routine employment of VR into the product development process (PDP) still finds an obstacle in the poor integration of the tools employed. The use of VR still needs long and quite hard procedures to work effectively; the models have to be converted into a format that is compatible with VR systems and each task requires an effort to prepare the virtual environment or to post-process the results that depend on the complexity of the task. This work analyses some VR applications into the PDP and describes some ideas to effectively support the operator that prepares the virtual environment. These ideas have been tested by developing four software interfaces, able to create an easy data exchange link between VR and other design tools like CAD, CAE and computer aided control engineering (CACE). © 2007 Springer-Verlag London Limited.

Keywords: CACE | CAD | CAD-VR integration | CAE | Virtual prototyping | Virtual reality

Abstract: In this study, a methodology based on co-simulation was developed for the multibody parametric modelling of a motorcycle with an anthropomorphic model of the rider. This co-simulation uses two different software programs, integrated to ensure a complete exchange of information between them in real time. The paper reports the effects induced by the movement of the rider's body on the dynamics and performance of a motorcycle. The legs of an anthropomorphic model were used as kinematics to control transverse movements of the motorcycle. The control system inputs are the geometric characteristics of the road (length, width and radius of curvature) and the speed of the vehicle along the track. For the dynamic behaviour of the motorcycle, the only channels currently operated by the control system are steering angle and engine torque, which are determined in accordance with the input parameters.

Keywords: Control | Dynamic | Motorcycle | Multibody | Rider

Abstract: Purpose - The purpose of this paper is to describe the method of virtually and physically reconstructing the missing part of a badly damaged medieval skull by means of reverse engineering, computer-aided design (CAD) and rapid prototyping (RP) techniques. Design/methodology/approach - Laser scanning data were used to create the 3D model of the damaged skull. Starting from this digital model, a virtual reconstruction of the missing part of the skull, based on the ideal symmetry with respect to the mid-sagittal plane, was achieved in a CAD environment. Finally, the custom-designed model was directly fabricated by means of the RP process. Findings - The result shows that the designed missing part of the skull fits very well with the existing skeletal remains. The final physical assembly of the prototyped element on the damaged skull was tested, restoring it to its whole original shape. Research limitations/implications - The entire process was time-consuming and may be applied just to the most representative skeletal remains. Practical implications - The method allows accurate fabrication of the missing part of the skull to be joined with the original skeletal remains. The advantage of using this technique is that the joining operation can be carried out without any need of supplementary connecting material, such as glue or plaster, to fix together the two parts. Originality/value - The reversible and non-invasive method improves the restoration process, reduces the risk of damage to the skeletal structure and allows reversion to the original repair as it was before. © Emerald Group Publishing Limited.

Keywords: Bones | Computer aided design | Rapid prototyping

Abstract: Background: At present the interest in medical field about the generation of three-dimensional digital models of anatomical structures increases due to the widespread diffusion of CAS - computer assisted surgery - systems. Most of them are based on CT - computer tomography - or MR - magnetic resonance - data volumes but sometimes this information is not available; there are only few X-ray, ultrasound or fluoroscopic images. Methods: This paper describes the study and the development of a script for a commercial software package (3ds Max) able to reconfigure the template model of a femur starting from two orthogonal images representing the specific patient's anatomy. Results: The script was used in several tests as summarized in this paper and the results appear to be interesting and acceptable, even for the medical experts that evaluated them. Conclusions: The script developed in this work allows the generation of the 3D model of a femur in a very simple way (the user interface has been developed obeying to the main usability guidelines) and using a widespread commercial package. The quality of the results can be compared to the quality of more expensive and specialized systems. © 2007 Elsevier Ireland Ltd. All rights reserved.

Keywords: Bone modelling | Computer aided design | Free form deformation | Image-based reconfiguration

Abstract: In this paper an integration between a computer aided 3D modeller and an augmented reality environment is presented. The system is based on an high resolution web cam to acquire video stream from the real world and an electromagnetic tracking system (Flock of Bird by Ascension) which allows the user to interact with real and virtual objects in the augmented scene. The software to manage user interaction and data flow is implemented in Visual C++ and it makes use of the Artoolkit libraries, the OpenGL libraries and the Flock of Birds libraries. The purpose of the system is to speed up reverse engineering and prototyping processes, because the user can relate real object features in the scene to model its virtual entities or acquire geometrical features of existing parts. Moreover, the user can export the virtual models into CAD system or import external models to see how they fit in their real environment.

Keywords: Augmented reality | CAD | Motion tracking

Abstract: This article is focused on the integration between KBE (Knowledge Based Engineering) applications for Design Automation (DA) and companies' data repositories managed by PLM (Product Lifecycle Management), and PDM (Product Data Management) systems. In particular, the authors conducted their research proposing a method to retrieve data or documents of pre-existing components from a document repository, before proceeding to design products. As result of that, designers save time spent in design, verifying loops and documents producing, thanks to the reuse of existing components or product. In order to illustrate their approach, the authors developed an application where the KBE system checks the availability of existing components or products before let the designer proceed to design. New produced documents are stored into the data repository for next design activities. The paper is organized as following: first, it starts with the description of some relevant aspects in engineering design: product and process representation, knowledge reuse and sharing, PDM and KBE functionalities; then, the paper continues analyzing the functionalities of KBE and PDM system in order to introduce the issue of the integration; third, it goes on describing the approach followed by the authors; next, it describes the application above mentioned and performed by the authors on these topics; finally, the results of the work are reported.

Keywords: Design Automation | KBE | PLM

Abstract: In the paper the design process, from the idea to the manufacturing aspects, with all the technical and technological problems, to develop a new competitive hard antitheft is described. The integrated use of the CAD/CAE and RP techniques made possible to analyse three different solutions in a very short time. The new model has completely designed, developed and patented (patent n. NA2005A000037) at the University of Naples and Cassino, Italy. It has weight and size very limited and some important features such as easiness to handle, high strength and high versatility; all this makes it an exclusive product of its type. The final product, made in AISI 1040 steel, is going to be manufactured and distributed in Europe by BULLOCK® in 2006.

Keywords: Antitheft | CAD | CAE | Lock system | Patent | PhD Researcher | RP Massimo Martorelli

Abstract: The author presents an original algorithm aimed at automatically generating the hull shape of a sailing yacht starting from an initial set of parameters. The procedure consists of two steps. First one keel line and a Designed Water Line (DWL in the following) are faired according to a set of parameters, say length of water line, canoe body draft, stem angle and some adimensional coefficients. This information is then used to fair the hull surface, which must in turn fulfil more prerequisites (parameters like displaty cement, floatation area and related coefficients). The hull is defined by means of a B-spline surface, the fairing of which is ensured by allowing for all the imposed objectives and constraints. An optimisation technique based upon the gradient method ensures that a reliable solution is obtained in a very short time. © 2005 Elsevier Ltd. All rights reserved.

Keywords: CAD | Optimisation | Surface fairing | Yacht design

Abstract: This paper presents a plug-in, named Cloth Assembler, implemented in the framework of the Italian PRIN Project (Research Project of National Interest) VI-CLOTH (Virtual CLOTHing). The base idea is to allow the designer to interactively define/the necessary information to assemble 2D panels on a virtual mannequin and to generate the 3D physical model in its initial configuration, initial step for the garment simulation process. Starting from 2D single pieces, ClothAssembler allows a user, as a virtual tailor, to specify assembly rules among cloth panels (e.g., cut lines, dart, and buttons), insert accessories, such as zips and hooks, and, finally specify finishings on single pieces and the presence of different textile multilayer, pockets, reinforcement lines, etc. The plug-in can be easily integrated with any commercial 2D CAD system and represents the connection element between 2D cloth world and 3D physics-based modelling and simulation systems. It has been validated with three real test-cases, a T-shirt, a denim skirt, and a pair of trousers.

Keywords: Apparel design | Assembly process | CAD | Cloth models | Virtual prototyping

Abstract: The aim of this work is an efficient methodology development for a real-time control of human assembling sequences of mechanical components. The method involves a CAD environment, an hardware system, referred to as a PAA (Personal Active Assistant), and a set of Mixed Reality features. The whole scheme is targeted to positively influence the connection between CAD and Mixed Reality in order to proficiently reduce the gap between engineers and manual operators. The system is based on a CAD assembly module and on an Mixed Reality wearable equipment. It can be used to improve several activities in the industrial field, such as operator professional training, optimal assembly sequence seeking or on-field teleconferencing (suitable for remote collaboration or for full exploitation of Concurrent Engineering suggestions during design and set up stages). The main characteristic of PAA is a real-time wireless linkage to a remote server or designer workstation, where project geometric database is stored. The Mixed Reality wearable equipment consists of an optical see-through display device and a PAA head-mounted camera. The user can freely operate in the mixed environment, while the camera can record the human driven assembly sequence and check the efficiency and correctness via object recognition: an incrementally sub-assembly detection algorithm has been developed in order to achieve complex dataset monitoring. Conversely, designer or assembly planner can exploit the peculiarities of Mixed Reality-based assembly: a straightforward interaction with the assembly operator can be obtained by sending vocal advices or by displaying superimposed visual information on the real scene. In the paper a new method for CAD models and Mixed Reality environment integration will be presented and discussed in order to improve and simplify personnel training or warehouse part seeking. © 2006 - IOS Press and the auther(s). All rights reserved.

Keywords: Assembly | CAD | Concurrent engineering | Mixed reality

Abstract: This work presents a CAD prototype, named ClothAssembler, targeted at complex-shaped apparel design for real manufacturing. The intent is to fill a gap in the current CAD technology for garment design as it is mainly conceived for 2D/3D geometric modelling of cloth shapes, but generally does not provide high level operators that allow interactive and easy design of aesthetic/functional features that characterize the garment pieces, and relations/connections between parts. Though still an academic prototype, ClothAssembler allows to define/choose in an interactive way all the necessary geometric and functional information for the design and finishing of 2D pieces, such as insertion of textile layers, reinforcement lines, pockets, cut lines and pleats, as well as topological information about how pieces are pair-wise connected and assembled, by definition of seams, darts, zips, constraints such as buttons and hooks, etc. A taxonomy and parametrization of cloth tailoring features is discussed, and system functionalities are presented, with applications to garment models of real production. © 2005 by CAD Solutions Company Limited.

Keywords: CAD | Garment design | Tailoring features

Abstract: The purpose of this research -based on CFD- is the evaluation of the aerodynamic performance of the geometry of a scooter. The analysis is mainly directed to investigate stability, safety and comfort aspects rather than aerodynamic fairness. A parametric simplified model was created and investigated. The model is composed of few plane panels which outline a commercial scooter. Pitching moment, velocity and turbulence fields are evaluated for different configurations and compared. The results are validated through a wind tunnel test campaign and are presented in the form of carpet plots which can drive the designer in his choices.

Keywords: Modelling | Motorcycles | Simulation

Abstract: We have developed a pen device for CAD applications in virtual reality which provides novel features compared to existing systems. The SenStylus consists of a wireless pen designed to be ergonomically handled by the user for spatial interaction using a six degree of freedom optical tracking. In addition to the c