[Elenco soci]

Cappetti Nicola

Professore Ordinario

Università degli Studi di Salerno

Sito istituzionale
SCOPUS ID: 6508129131
Orcid: 0000-0002-5843-2805

Pubblicazioni scientifiche

[1] Cappetti N., Pierri S., Fontana C., Skeleton and Medial Axis Functions Evaluation of Voxel Discretized Geometries, Lecture Notes in Mechanical Engineering, 204-216, (2023). Abstract

Abstract: In the field of medical image processing, the resolution capacity exhibited by the initial diagnostic investigations is becoming increasingly important. With respect to them, in fact, the row image set is subjected to three-dimensional reconstruction analysis, by partitioning the regions of interest, as well as to local investigations, aimed, for example, at the extrapolation of topological information, relating to the morphology of the object that needs to be investigated. The accuracy of these functions is, however, difficult to quantify, due to the lack of three-dimensional models that act as a reference Gold Standard. The reproduction of CT-type diagnostic acquisitions, starting from a virtual scanning procedure of a starting known three-dimensional geometry is used. To do this, triangular tessellated three-dimensional models of various geometries were examined. These were broken down into cubic elements, equal in size to those of a common voxel, thus resulting in a volume scan simulation of the original region considered. The structure thus obtained was then subjected to skeletonization and medial axis algorithms to evaluate the effectiveness of some of the most commonly used functions in medical processing. A virtual scanning model of this type can be an extremely effective evaluation analysis tool in discriminating the resolutive quality of the medical image processing functions. From a qualitative comparison of this type, it is possible to optimize automated anatomical investigation algorithms, making a significant contribution in the refinement of the techniques, now more and more demanding, of image processing in the biomedical field.

Keywords: Medical image acquisition | Thinning and Medial Axis | Voxelization

[2] Salvati L., Cappetti N., d’Amore M., Fiorentino A., Pellegrino A., Sena P., Villecco F., HRV Analysis Through the Sphygmic Wave Pulsation of the Femoral Artery, Lecture Notes in Mechanical Engineering, 1495-1504, (2023). Abstract

Abstract: The need, due to road safety reasons, to constantly monitor the physiological conditions of a driver (stress, concentration, fatigue) as well as the alterations to the comfort state of the driving position in long-haul journey, has led many car manufacturers to focus attention on the development of innovative technologies and methods that include the monitoring of biosignals that can be acquired by the driver himself. The possibility of detecting and processing such a signal in real time was the object of this research, which allowed to produce a technology that exploited the analysis of Heart Rate Variability (HRV), a method widely used in clinical field for the analysis of the autonomic nervous system (ANS) with respect to daily biological rhythm stress, comfort or vigilance. While the conventional cardiac signal acquisition system uses clinical instruments such as the electrocardiograph (ECG), in this study a technique is developed that allows the detection and processing of the pulsation signal at the level of the femoral artery through a sensor placed on the driver's seat. The main advantage consists in having a control in real time by avoiding the application of sensors on the skin. In fact, three fundamental parameters: the heart rate (HR), the interval between beats (RRI) and the typical HRV indices are determined, by using a suitable signal analysis algorithm. The comparison with equivalent values obtained by a conventional ECG device shows a Pearson correlation between 0.35 to and 0.94. This may be of a great help in evaluating thesympathovagal balance.

Keywords: HCD | HRV | RRI

[3] di Filippo A., Gujski L.M., Cappetti N., Villecco F., Traceability of Uncertainty in Building Information Modelling Processes for Existing Structures, Lecture Notes in Mechanical Engineering, 895-902, (2023). Abstract

Abstract: The reusability of informative content throughout the building life cycle is a current issue in the AEC sector. One of the cornerstones of BIM is to guarantee the availability and portability of data which, against a greater initial investment for the construction of the model, will offer a multidisciplinary and integrated tool to support all possible operations on the building. The issue becomes even more complicated in the case of cultural heritage or existing structures where the information process starts directly from the operation stage (management and maintenance phases) and provides, through reverse engineering methodology, an Asset Information Model. It is therefore essential to keep track of the levels of accuracy of this content, in relation to the geometric and informative attributes of all the objects that make up the model. Starting from a careful analysis of the state of the art related to these issues, this paper proposes a possible approach to the statistical treatment of uncertainties related to geometric attributes in case of Historic or Existing BIM, differentiating between the products of the survey and those of the subsequent parametric modelling.

Keywords: Detected accuracy | Modelled accuracy | Scan-to-BIM

[4] Iaquinandi M., Fontana C., Fiorillo I., Naddeo A., Cappetti N., Performance Evaluation of an Immersive Measurement Instrument for Automotive Field Applications, Lecture Notes in Mechanical Engineering, 1426-1435, (2023). Abstract

Abstract: The development of cutting-edge technologies in the industrial sector has led to the demand for increasingly specific tools in the optimization of efficiency problems. The automotive sector is the one that makes the most use of these technologies, such as, among all, Virtual Reality (VR) and Augmented Reality (AR). A virtual reality tool is inserted as a guide tool for the user in drawing as quickly as possible the key information for optimizing the process. This research work fits into this context, the goal of which was the implementation of an immersive platform for carrying out accurate measurements within an entirely virtual automotive environment. A VR system of this type allows to check the dimensional and shape tolerances of car components, performing measurement, with high precision and in real time, in a custom-made virtual environment, in which it is possible to simulate the presence of a myriad of components and test their mutual interaction. A comparative test was carried out, obtained by varying the graphical and geometrical model in the VR settings, in order to evaluate the level of usability and the degree of efficiency of a tool for measuring distances between objects in a virtual reality environment, depending on the system parameters. The validation of a measurement instrument in VR is part of an increasingly current technological context in which the need to optimize the time-cost curve embraces the need for increasingly accurate results.

Keywords: Assembly training | Tolerance measurements | Virtual reality

[5] Di Brigida L., Naddeo A., Cappetti N., Borri A., Cortese A., Computer Aided Orthognathic Surgery: A General Method for Designing and Manufacturing Personalized Cutting/Repositioning Templates, Applied Sciences (Switzerland), 12(7), (2022). Abstract

Abstract: Orthognathic surgery allows broad-spectrum deformity correction involving both aesthetic and functional aspects on the TMJ (temporo-mandibular joint) and on the facial skull district. The combination of Reverse Engineering (RE), Virtual Surgery Planning (VSP), Computer Aided Design (CAD), Additive Manufacturing (AM), and 3D visualization allows surgeons to plan, virtually, manipulations and the translation of the human parts in the operating room. This work’s aim was to define a methodology, in the form of a workflow, for surgery planning and for designing and manufacturing templates for orthognathic surgery. Along the workflow, the error chain was checked and the maximum error in virtual planning was evaluated. The three-dimensional reconstruction of the mandibular shape and bone fragment movements after segmentation allow complete planning of the surgery and, following the proposed method, the introduction of both the innovative evaluation of the transversal intercondylar distance variation after mandibular arch advancement/set and the possibility of use of standard plates to plan and realize a customized surgery. The procedure was adopted in one clinical case on a patient affected by a class III malocclusion with an associated open bite and right deviation of the mandible with expected good results. Compared with the methods from most recent literature, the presented method introduces two elements of novelty and improves surgery results by optimizing costs and operating time. A new era of collaboration among surgeons and engineer has begun and is now bringing several benefits in personalized surgery.

Keywords: 3D-modelling | computer-aided surgery | methodology | orthognathic surgery | rapid manufacturing | surgical template

[6] Salvati L., Cappetti N., d’Amore M., Fiorentino A., Pellegrino A., Sena P., Villecco F., Heart Sound Processing Model for a Mat-Shaped Device, Lecture Notes in Mechanical Engineering, 809-817, (2022). Abstract

Abstract: The development and spread of human-centered products that are increasingly simple and affordable has seen their application areas increase over the years, as well as their effectiveness and reliability. The study of a model based on the interpretation of biosignals is able to provide real-time monitoring of physiological conditions and to offer useful support in both clinical and driving safety fields. Heart rate variability (HRV) analysis is useful in assessing the dynamics of the autonomic nervous system (ANS) and detecting the effects of numerous systemic diseases as well as changes related to the normal daily biological rhythm or to accidental situations of stress or fatigue, as well as comfort or vigilance. The conventional system for the acquisition of the electrocardiographic (ECG) signal uses a methodology that provides for the contact of electrodes with the human skin. This research proposes a detection platform without direct contact with the skin capable of acquiring cardiac signals in real time: through a digital signal processing algorithm able of filtering noise and identifying peaks, heart rate (HR), the interval between beats (RRI) and the characteristic indices of HRV in the time and frequency domain are determined. The parameters were compared with those of a conventional ECG using the Pearson correlation coefficient which produced an index ranging from 0.30 to 0.78 for the tachogram, managing to provide, in the cases less affected by noise, a correspondence in the results of the spectral analysis useful for the evaluation of sympatho-vagal balance.

Keywords: HRV | Human-centered-design | Non-invasive | RRI

[7] di Filippo A., Villecco F., Cappetti N., Barba S., A Methodological Proposal for the Comparison of 3D Photogrammetric Models, Lecture Notes in Mechanical Engineering, 930-937, (2022). Abstract

Abstract: The field of simplification of geometric surfaces still lacks a formal and universally recognized definition of the error, which should involve both the approximation of the shape and the conservation of the other attributes of the mesh (starting from the colour). In order to solve this problem, we propose a hypothesis of methodological comparison that allow the evaluation of differences between two homologous surfaces, quantified employing the Hausdorff distance. The main advantage of this method is the independence from sampling techniques used to produce the mesh, without losing its characteristics of objectivity and generality. The Hausdorff distance geometrically represents the distance between two sets A and B in a suitable metric space, and it is defined as the maximum between the excess of A over B and the excess of B over A. This value is then compared with the average length of the diagonals of the “bounding boxes” of the homologous models, i.e. the parallelepipeds corresponding to the minimum volume that completely envelops each set; this results in an effective representation of error in relative terms.

Keywords: Accuracy assessment | Cultural Heritage | Hausdorff distance | Mesh

[8] Quatrano A., Fontana C., Rubino F., Cappetti N., Carlone P., Analysis of the influence of inner morphology on blood flow in 3D-printed bone scaffolds, Procedia CIRP, 110(C), 226-231, (2022). Abstract

Abstract: In recent years, 3D printed scaffolds have been proposed as promising alternative to the conventional cell culture techniques. Scaffolds, indeed, allow the development of a higher number of cellular connections along the three dimensions favoring the cell regeneration, which make them particularly suitable in case of implants for deteriorate bones in old age patients. Besides the characteristics of biocompatibility and biodegradability fundamental for the integration of the scaffolds with the human body, the inner morphology, the permeability as well as the porosity are parameters of paramount relevance in the design of 3D-printed scaffolds influencing the flow of the blood through the cells and, thus, their metabolic functions. In the present work the influence of the internal geometry of 3D-printed scaffolds on the blood flow was investigated. Five cylindrical scaffolds having different internal geometry and different porosity were fabricated using parametric design technique. Numerical analysis of the blood flow within the designed structures was conducted by using CFD tool.

Keywords: additive manufacturing | blood flow simulation | bone scaffolds | parametric design | porous metal

[9] Russo A., Licciardo G.D., Benedetto L.D., Rubino A., Liguori R., Naddeo A., Cappetti N., Quantized Fully Convolution Neural Network for HW Implementation of Human Posture Recognition, 2021 IEEE 3rd International Conference on Artificial Intelligence Circuits and Systems, AICAS 2021, (2021). Abstract

Abstract: In this paper, a very tiny HW design of a Quantized Fully Convolutional Neural Network is proposed which demonstrates that accurate Human Posture Recognition can be designed by exploiting only pressure sensors and keeping the computation close to the data sources, according to the edge computing paradigm. The custom design of the QFCN exploits a base-2 quantization scheme to achieve state-of-The-Art performances in terms of classification accuracy, together with a very reduced number of mapped physical resources and power consumption. Trained and validated on a public dataset for in-bed posture classification, the QFCN exhibits an accuracy up to 96.77% in recognizing 17 different postures. When prototyped on a Xilinx Artix 7 FPGA the design achieves less than 7 mW dynamic power dissipation and a maximum operation frequency of 26.6 MHz, compatible with an Output Data Rate (ODR) of the sensors of 9.13 kHz.

Keywords: Convolutional neural network | FPGA custom design | low-power digital design | Quantization scheme

[10] Licciardo G.D., Russo A., Naddeo A., Cappetti N., Di Benedetto L., Rubino A., Liguori R., A resource constrained neural network for the design of embedded human posture recognition systems, Applied Sciences (Switzerland), 11(11), (2021). Abstract

Abstract: A custom HW design of a Fully Convolutional Neural Network (FCN) is presented in this paper to implement an embeddable Human Posture Recognition (HPR) system capable of very high accuracy both for laying and sitting posture recognition. The FCN exploits a new base-2 quantization scheme for weight and binarized activations to meet the optimal trade-off between low power dissipation, a very reduced set of instantiated physical resources and state-of-the-art accuracy to classify human postures. By using a limited number of pressure sensors only, the optimized HW implementation allows keeping the computation close to the data sources according to the edge computing paradigm and enables the design of embedded HP systems. The FCN can be simply reconfigured to be used for laying and sitting posture recognition. Tested on a public dataset for in-bed posture classification, the proposed FCN obtains a mean accuracy value of 96.77% to recognize 17 different postures, while a small custom dataset has been used for training and testing for sitting posture recognition, where the FCN achieves 98.88% accuracy to recognize eight positions. The FCN has been prototyped on a Xilinx Artix 7 FPGA where it exhibits a dynamic power dissipation lower than 11 mW and 7 mW for laying and sitting posture recognition, respectively, and a maximum operation frequency of 47.64 MHz and 26.6 MHz, corresponding to an Output Data Rate (ODR) of the sensors of 16.50 kHz and 9.13 kHz, respectively. Furthermore, synthesis results with a CMOS 130 nm technology have been reported, to give an estimation about the possibility of an in-sensor circuital implementation.

Keywords: Convolutional Neural Network | Human behavior | Low-power digital design | Posture recognition

[11] Cappetti N., Brancaccio C., De Sio F., Fontana C., A Novel Procedure to Design a Positionable and Stable Drilling Template for Spine Surgery, Lecture Notes in Mechanical Engineering, 200-205, (2021). Abstract

Abstract: Spine surgery is based, nowadays, on the use of cutting-edge instruments that optimize the intervention processes in the operating room, with advantages that affect the patient himself. Among these, rapid prototyping is configured as a first-rate tool, thanks to its ability to detail the diagnostic treatment according to the specific pathological case under examination. An example of this technology is represented by the generation of a drilling template, to assist the surgeon in identifying the optimal direction of insertion of the pedicle screws, capable of significantly reduce intervention times, in addition to the inevitable exposure of the patient to ionizing radiation, to which he is subjected during a normal arthrodesis intervention procedure. The design of a drilling guide requires, however, a particular attention in identifying the undercuts present on the vertebral surface, those areas of the spinous process which, reported inside the cavity of the template, involve complications at the time of extraction. In parallel, it is vitally important to carry out an evaluation of its stability during its use. In this article, starting from the analysis of the interferences present during the insertion of the template, a semi-automatic correction model is proposed for the generation of a new profile of the same, which facilitates its extraction without causing injury to the vertebral regions involved from the contact with the mask.

Keywords: Computer‐assisted surgery | Pedicle screw fixation | Spine | Surgical template insertion optimization | Undercuts

[12] Cappetti N., Manso E.D., Study of the relationships between articular moments, comfort and human posture on a chair, Work, 68(s1), S59-S68, (2021). Abstract

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

[13] Naddeo A., Cappetti N., Comfort driven design of innovative products: A personalized mattress case study, Work, 68(s1), S139-S150, (2021). Abstract

Abstract: BACKGROUND: Human-centred design asks for wellbeing and comfort of the customer/worker when interacting with a product. Having a good perception-model and an objective method to evaluate the experienced (dis)comfort by the product user is needed for performing a preventive comfort evaluation as early as possible in the product development plan. The mattress of a bed is a typical product whose relevance in everyday life of people is under-evaluated. Fortunately, this behaviour is quickly changing, and the customer wants to understand the product he/she buys and asks for more comfortable and for scientifically assessed products. No guidelines for designing a personalized mattress are available in the literature. OBJECTIVES: This study deals with the experience of designing an innovative product whose product-development-plan is focused on the customer perceived comfort: a personalized mattress. The research question is: which method can be used to innovate or create a comfort-driven human-centred product? METHODS: Virtual prototyping was used to develop a correlated numerical model of the mattress. A comfort model for preventively assessing the perceived comfort was proposed and experimentally tested. Mattress testing sessions with subjects were organized, and collected data were compared with already tested mattresses. Brainstorming and multi-expert methods were used to propose, realize, and test an archetype of a new mattress for final comfort assessment. RESULTS: A new reconfigurable mattress was developed, resulting in two patents. The mattress design shows that personalized products can be tuned according to the anthropometric data of the customer in order to improve the comfort experience during sleep. CONCLUSIONS: A 'comfort-driven design guideline' was proposed; this method has been based on the use of virtual prototyping, virtual optimization and physical prototyping and testing. It allowed to improve an existing product in a better way and to bring innovation in it.

Keywords: Comfort | design | innovation | mattress | personalized product

[14] Naddeo F., Cataldo E., Narciso N., Naddeo A., Cappetti N., "In vivo" validation of 3d-printed innovative surgical template for lumbar spinal arthrodesis, Applied Sciences (Switzerland), 10(17), (2020). Abstract

Abstract: The most common type of spine instrumentation is the pedicle screw fixation. The recent literature shows how customized drilling templates help surgeons to perform the surgery better. This work aims to validate the design of a customized template for inserting lumbar pedicle screw via a procedure based on rapid prototyping and reverse engineering techniques and to show the benefits. The novelties of this template are its low-invasive sizes, its design based on a patented algorithm, which calculates the sizes of the screws and the optimal insertion direction, the engage/disengage system, and the adaptability to every kind of surgeon's kit. Accuracy of pedicle screw location, surgery duration, and X-ray exposition have been used to evaluate the performances of the template. Mono-centric in vivo trial was performed. Twenty patients (8 women and 12 men) were enrolled randomly corresponding to sixty vertebrae treated with spinal arthrodesis (30 with and 30 without templates). Accuracy of the screw positioning and reduction in both surgery duration and patients' exposure to X-rays achieved excellent results because the time spent on the insertion of pedicle screws via the surgical template was cut down by about 63%, while the number of X-ray shots was reduced by about 92%. The proposed template performed better than the standard approach and could be helpful both for skilled and novice surgeons.

Keywords: Lumbar spinal arthrodesis | Screw location optimisation | Spine surgery | Surgical template | X-ray minimisation

[15] Cappetti N., Naddeo A., Soldovieri V.M., Vitillo I., Fiorillo I., Perceived Comfort and Muscular Activity: A Virtual Assessment of Possible Correlations, Lecture Notes in Mechanical Engineering, 59-70, (2020). Abstract

Abstract: Generally, comfort may be defined as the “level of well-being” perceived by humans in a working environment. The state-of-the-art about the evaluation of comfort/discomfort shows the need for an objective method to evaluate the “effect in the internal body” and “perceived effects” in main systems of comfort perception. Some medical studies show that each human joint has its own natural Rest Posture in which human muscles are completely relaxed or at the minimum strain level. Basing on this assumption, in other studies postural comfort curves for each Degree of Freedom of human upper and lower-limbs joints have been studied and CaMAN software has been developed to have a direct interface with these curves. In this paper, the upper limbs’ postural comfort curves have been compared with the results gained by the biomechanics virtual simulation built on ANYBODY Software. A detailed study has been conducted on the upper body muscular activation during upper limbs movement with and without load. Postures have been analysed both by ANYBODY and CaMAN in order to correlate the postural (dis)comfort perception with the calculated muscular activity.

Keywords: ANYBODY software | Human Man Interface simulation | Postural comfort

[16] Rodríguez-Montaño Ó.L., Cortés-Rodríguez C.J., Naddeo F., Uva A.E., Fiorentino M., Naddeo A., Cappetti N., Gattullo M., Monno G., Boccaccio A., Irregular Load Adapted Scaffold Optimization: A Computational Framework Based on Mechanobiological Criteria, ACS Biomaterials Science and Engineering, 5(10), 5392-5411, (2019). Abstract

Abstract: By combining load adaptive algorithms with mechanobiological algorithms, a computational framework was developed to design and optimize the microarchitecture of irregular load adapted scaffolds for bone tissue engineering. Skeletonized cancellous bone-inspired lattice structures were built including linear fibers oriented along the internal flux of forces induced by the hypothesized boundary conditions. These structures were then converted into solid finite element models, which were optimized with mechanobiology-based optimization algorithms. The design variable was the diameter of the beams included in the scaffold, while the design objective was the maximization of the fraction of the scaffold volume predicted to be occupied by neo-formed bony tissue. The performance of the designed irregular scaffolds, intended as the capability to favor the formation of bone, was compared with that of the regular ones based on different unit cell geometries. Three different boundary and loading conditions were hypothesized, and for all of them, it was found that the irregular load adapted scaffolds perform better than the regular ones. Interestingly, the numerical predictions of the proposed framework are consistent with the results of experimental studies reported in the literature. The proposed framework appears to be a powerful tool that can be utilized to design high-performance irregular load adapted scaffolds capable of bearing complex load distributions.

Keywords: finite element method | irregular and regular scaffolds | load adaptive algorithms | mechanobiological algorithms | robustness of optimized structures | structural optimization algorithms

[17] Smulders M., Naddeo A., Cappetti N., van Grondelle E.D., Schultheis U., Vink P., Neck posture and muscle activity in a reclined business class aircraft seat watching IFE with and without head support, Applied Ergonomics, 79, 25-37, (2019). Abstract

Abstract: The purpose of this study is to research if a headrest benefits the comfort of the passenger and lowers muscle activity in the neck when sitting in a reclined (slouched)posture while watching in flight entertainment (IFE)in an aircraft business class seat. No significant differences in muscle activity in the musculus sternocleidomastoid and musculus trapezius pars descendant were found between the conditions with headrest and without headrest. A significant difference in expected comfort rating was found. Subjects indicated they expect to experience more comfort with a headrest when watching IFE for a duration of two movies during a long-haul flight. This study also found a significant difference in posture. In the condition without headrest the head was more upright compared to the condition with headrest. The lack of significant difference in muscle activity and the significant difference in posture may indicate that humans tend to look for a head position that is neutral, in the sense of minimal muscle effort. This study shows that the use of a headrest may benefit the comfort experience of the passenger during flight. However, further research is necessary on the design of the headrest and the long-term effects of head support on comfort, discomfort, muscle activity and fatigue for watching IFE in a slouched posture.

Keywords: Aircraft seat | Comfort | EMG | Headrest | Neck angle | Posture | TV

[18] Naddeo F., Fontana C., Naddeo A., Cataldo E., Cappetti N., Narciso N., Novel design for a customized, 3D-printed surgical template for thoracic spinal arthrodesis, International Journal of Medical Robotics and Computer Assisted Surgery, 15(4), (2019). Abstract

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

[19] Naddeo A., Cappetti N., Vallone M., Assessment of ranges of rest postures of human lower limbs, Work, 63(2), 219-229, (2019). Abstract

Abstract: BACKGROUND: Several comfort perception models have proposed an objective method to evaluate 'effects in the internal body' and 'perceived comfort'. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. OBJECTIVE: The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for lower limbs. METHODS: The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. Data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. RESULTS: RRPs for lower limbs of men and women have been identified and can be used for virtual comfort assessment. CONCLUSIONS: This paper shows a method to evaluate in a more objective way the subjective postural comfort perception and results allow researchers to improve models for the virtual preventive comfort assessment.

Keywords: Comfort evaluation | lower limbs joints | range of motion | rest posture

[20] Fasulo L., Naddeo A., Cappetti N., A study of classroom seat (dis)comfort: Relationships between body movements, center of pressure on the seat, and lower limbs' sensations, Applied Ergonomics, 74, 233-240, (2019). Abstract

Abstract: The aim of this work is to define a new method that helps researchers to analyze perceptions of (dis)comfort in dynamic conditions. Recent studies pay considerable attention to body movements, mobility, and stability to measure comfort or discomfort when seated. Most of these discuss the relations between subjective comfort/discomfort and objective measurements (e.g. body pressure distribution, body movement and EMG) for short- and medium-term sitting. The present analysis took place in a classroom of the Industrial Engineering Department at the University of Salerno. The participants included 25 students (12 females and 13 males), who were observed during classroom hours. The students were invited to sit at a combo-desk and were free to perform different combinations of movements while writing and listening. These activities required that they adapt their body movements, as the combo-desk was fixed to the floor. A pressure pad was used to detect pressure at interface and center of pressure's changes, allowing for the bodies' motion data to be recorded. The aim was to identify the correct threshold to be used for movement detection and to investigate correlations between the number of movements and the perceived (dis)comfort. The study also identifies those body parts that have the greatest effect on (dis)comfort perception.

Keywords: Body movements | Center of pressure | Classroom seat | Comfort | Discomfort | Pressure map | School furniture

[21] Naddeo A., Cappetti N., Vallone M., Range of rest posture of human lower limbs, Advances in Intelligent Systems and Computing, 824, 33-46, (2019). Abstract

Abstract: The most advocated schemes of comfort perception have proposed an objective method to evaluate “effects in the internal body” and “perceived effects”—the state of the art for comfort/discomfort evaluation. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. [1], useful for comfort evaluation. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for these human joints in the lower limbs: hip, knee, and ankle. The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. The experimental data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. These positions were among the most important information in the comfort evaluation analyses.

[22] Cappetti N., Naddeo A., On methods to identify the symmetry line of human back, International Journal on Interactive Design and Manufacturing, 12(4), 1265-1271, (2018). Abstract

Abstract: This paper analyse and compare the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical discussion of the state of the art in order to highlight real potentialities and limitations of the most important methodologies proposed for human symmetry line detection.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

[23] Coppola B., Cappetti N., Maio L.D., Scarfato P., Incarnato L., 3D printing of PLA/clay nanocomposites: Influence of printing temperature on printed samples properties, Materials, 11(10), (2018). Abstract

Abstract: Abstract: In this study, the possibility of using a layered silicate-reinforced polylactic acid (PLA) in additive manufacturing applications was investigated. In particular, the aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, two PLA grades (4032D and 2003D, D-isomer content 1.5 and 4, respectively) were melt-compounded by a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt %. Then, PLA and PLA/clay feedstock filaments (diameter 1.75 mm) were produced using a single screw extruder. Dog-bone and prismatic specimens were 3D printed using the FDM technique at three different temperatures, which were progressively increased from melting temperature (185-200-215 °C for PLA 4032D and 165-180-195 °C for PLA 2003D). PLA and PLA/clay specimens were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile tests. Moreover, the morphology of the 3D printed specimens was investigated using optical microscopy and contact angle measurements. The different polymer matrix and the resulting nanocomposite morphology strongly influenced 3D printed specimen properties. DMA on PLA/clay filaments reported an increase in storage modulus both at ambient temperature and above the glass transition temperature in comparison to neat PLA filaments. Furthermore, the presence of nanoclay increased thermal stability, as demonstrated by TGA, and acted as a nucleating agent, as observed from the DSC measurements. Finally, for 3D printed samples, when increasing printing temperature, a different behavior was observed for the two PLA grades and their nanocomposites. In particular, 3D printed nanocomposite samples exhibited higher elastic modulus than neat PLA specimens, but for PLA 4032D+C30B, elastic modulus increased at increasing printing temperature while for PLA 2003D+C30B slightly decreased. Such different behavior can be explained considering the different polymer macromolecular structure and the different nanocomposite morphology (exfoliated in PLA 4032D matrix and intercalated in PLA 2003D matrix).

Keywords: 3D printing | Clay | FDM | Nanocomposites | PLA

[24] Naddeo F., Naddeo A., Cappetti N., Cataldo E., Militio R., Novel procedure for designing and 3D printing a customized surgical template for arthrodesis surgery on the sacrum, Symmetry, 10(8), (2018). Abstract

Abstract: In this article, the authors propose a novel procedure for designing a customized 3D-printed surgical template to guide surgeons in inserting screws into the sacral zone during arthrodesis surgeries. The template is characterized by two cylindrical guides defined by means of trajectories identified, based on standard procedure, via an appropriate Computer-Aided-Design (CAD)-based procedure. The procedure is based on the definition of the insertion direction by means of anatomical landmarks that enable the screws to take advantage of the maximum available bone path. After 3D printing, the template adheres perfectly to the bone surface, showing univocal positioning by exploiting the foramina of the sacrum, great maneuverability due to the presence of an ergonomic handle, as well as a break system for the two independent guides. These features make the product innovative. Thanks to its small size and the easy anchoring, the surgeon can simply position the template on the insertion area and directly insert the screws, without alterations to standard surgical procedures. This has the effect of reducing the overall duration of the surgery and the patient's exposure to X-rays, and increasing both the safety of the intervention and the quality of the results.

Keywords: Computer-aided surgery | Orthopaedic device | Patient-specific guide | Rapid prototyping | X-ray minimization

[25] Coppola B., Cappetti N., Di Maio L., Scarfato P., Incarnato L., Influence of 3D printing parameters on the properties of PLA/clay nanocomposites, AIP Conference Proceedings, 1981, (2018). Abstract

Abstract: The aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, PLA 4032D was melt compounded in a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt%. Then, using a single screw extruder, PLA and PLA/clay filaments were produced so as to obtain the required diameter (1.75 mm). Finally, dog-bone specimens were 3D printed via FDM technique using three different temperatures (185, 200 and 215°C) and such specimens were mechanically tested in tensile mode. Dynamic mechanical analysis (DMA) on PLA/clay filaments reported an increase of storage modulus both at 35°C and 70°C (8 and 40 %, respectively) in comparison to the PLA filament. Differential scanning calorimetry (DSC) demonstrated the ability of nanoclay to act as nucleating agent because cold crystallization temperature decreased of about 10°C. Finally, nanocomposite 3D printed samples exhibited always higher elastic modulus than PLA specimens and it increases at increasing printing temperature.

Keywords: 3D printing | FDM | nanocomposites | PLA

[26] Naddeo A., Cappetti N., Additive manufacturing for industrial benchmarking: An application to vehicle's under-hood design, ARPN Journal of Engineering and Applied Sciences, 13(14), 4292-4299, (2018). Abstract

Abstract: All over the world, and mainly in United States, since 1977 to 1991 the research centers of automotive companies have processed several statistical data on real accidents between vehicles and pedestrians taking care, obviously, to pedestrians' injury. In latest years, a research group of EEVC (European Enhanced Vehicle-Safety Committee) had realized some documents about "pedestrian test" procedures. In reference papers of period 1977 - 1997 and in EEVC documents, the scientists describe a proposed homologating test for child-head impact; it is represented by the impact of some standardized impactors on car bonnet, in order to evaluate the child-head injury as deceleration of its gravity center. Injury evaluation criteria is an energy criterion and is quantified by the HPC index (see below) calculated by acceleration resultant vector, measured by an accelerometer mounted in the head- impactor. Our research wants to propose a new potential-injury evaluation method based on virtual reconstruction of the surface that envelope all the deformation surfaces in internal part of the bonnet and on its rapid prototyping. This surface is so processed and rapid prototyped as a puzzle of shells with their support. This prototyped surface is super-imposed on the real under-bonnet layout of a car and allows to evaluate easily where and how much our deformed bonnet could hit the hard-parts of the engine layout. This paper shows the results of this research project.

Keywords: Additive manufacturing | Industrial benchmarking | Rapid prototyping | Vehicle design

[27] Cappetti N., Naddeo A., Salerno G., Influence of control parameters on consumer FDM 3D printing, Advances in Transdisciplinary Engineering, 7, 165-177, (2018). Abstract

Abstract: Rapid prototyping (RP) is a set of technologies that permits building a physical model directly from its design by implementing a single automatic process using a 3D model of the object to be printed. RP systems can be based on different Additive Manufacturing (AM) technologies, such as a Fused Deposition Modeling (FDM) machine that works by extruding and melting together fused plastic filaments, drawing the boundaries and filling the model thin layer by thin layer. Low-cost FDM 3d printers do not work well automatically but require of a calibration phase because the best configuration settings in the slicing software are unknown, and the number of parameters values that needs to be manually defined is very large. The scientific literature reports many interesting articles on this topic, describing how the process can be improved by choosing the correct values of various parameters. Internet websites such RepRap.org discuss 3D printers and ppost detailed FAQ sections where users described improvements in 3D printing with simple methods but with great effort in terms of costs and time. Yet not all questions are answered. This paper would introduces: a) a new method for the analysis of the slicing software parameters that can be done with easy models; b) a second method for improving the effects of the parameters that shows a higher influence in the signal-to-noise ratio analysis.

Keywords: Digital fabrication | FDM | NIST artifact | Rapid prototyping | RepRap

[28] Coppola B., Cappetti N., Di Maio L., Scarfato P., Incarnato L., Layered silicate reinforced polylactic acid filaments for 3D printing of polymer nanocomposites, RTSI 2017 - IEEE 3rd International Forum on Research and Technologies for Society and Industry, Conference Proceedings, (2017). Abstract

Abstract: In this study, the possibility to use a layered silicate reinforced polylactic acid (PLA) in additive manufacturing applications was investigated. In particular, after melt compounding in a twin-screw extruder a filament for 3D printing applications was produced using a single-screw extruder. The influence of nanoclay on mechanical, thermal and viscoelastic properties of the produced filaments was investigated. Differential scanning calorimetry (DSC) results reveal an increase in crystallinity for the nanocomposites and the presence of two crystalline forms (α and α'). Dynamic mechanical thermal analysis (DMA) results show that storage modulus increased for the nanocomposites when compared with neat PLA. Finally, the extruded PLA/clay filaments were successfully 3D printed using fused deposition modelling (FDM) technique. The printed nanocomposites showed a higher elastic modulus (15%) compared to printed samples of neat PLA. Moreover, PLA/clay printed samples present also a better shape stability, showing sharper edges.

Keywords: 3D printing | FDM | nanocomposites | PLA

[29] Naddeo F., Cataldo E., Naddeo A., Cappetti N., Narciso N., An automatic and patient-specific algorithm to design the optimal insertion direction of pedicle screws for spine surgery templates, Medical and Biological Engineering and Computing, 55(9), 1549-1562, (2017). Abstract

Abstract: Many diseases of the spine require surgical treatments that are currently performed based on the experience of the surgeon. For pedicle arthrodesis surgery, two critical factors must be addressed: Screws must be applied correctly and exposure to harmful radiation must be avoided. The incorrect positioning of the screws may cause operating failures that lead to subsequent reoperations, an increase in the overall duration of surgery and, therefore, more harmful, real-time X-ray checks. In this paper, the authors solve these problems by developing a method to realize a customized surgical template that acts as a drilling template. The template has two cylindrical guides that follow a correct trajectory previously calculated by means of an automatic algorithm generated on the basis of a vertebra CAD model for a specific patient. The surgeon sets the template (drilling guides) on the patient’s vertebra and safely applies the screws. Three surgical interventions for spinal stabilization have been performed using the template. These have had excellent results with regard to the accuracy of the screw positioning, reduction of the overall duration of the intervention, and reduction of the number of times the patient was exposed to X-rays.

Keywords: Pedicle arthrodesis | Screw direction optimization | Spine surgery | Surgical template | X-ray minimization

[30] Naddeo F., Cappetti N., Naddeo A., Novel “load adaptive algorithm based” procedure for 3D printing of cancellous bone-inspired structures, Composites Part B: Engineering, 115, 60-69, (2017). Abstract

Abstract: This work shows the practical application and the experimental validation of a procedure based on an algorithm, running in a finite element environment, able to operate inside a convex three-dimensional solid by replacing the continuous mass with an appropriate cancellous bone-inspired space frame sharing, with the solid, the border and organized for having the fibres oriented according to the boundary conditions. The purpose is to reach the maximum mechanical efficiency realizing a load adaptive space frame optimized in terms of weight. Young's moduli of a cubic virtual specimen were numerically estimated. Fifteen specimens were printed by a 3D printer using a titanium alloy. Numerical results were compared with experimental ones obtained by tensile tests. The simulation results confirmed the validity of the FEM “beam element-based” space frame.

Keywords: 3-Dimensional printing | Directional orientation | Fibres | Finite element analysis (FEA) | Mechanical testing

[31] Naddeo F., Naddeo A., Cappetti N., Novel “load adaptive algorithm based” procedure for 3D printing of lattice-based components showing parametric curved micro-beams, Composites Part B: Engineering, 115, 51-59, (2017). Abstract

Abstract: This work deals with the development, the application and the experimental validation of a procedure based on an algorithm, running in a finite element environment replacing the continuous mass of convex solids with a cancellous bone-inspired lattice structure showing curved beams oriented on the basis of the external forces, sharing with it border and boundary conditions. For the validation of the new lattice structure a cubic representative volume element, showing curved micro-beams, was chosen, implementing periodic boundary conditions. At the end, the algorithm created a. stl file to be printed by a 3D printer using an appropriate polymer. The numerical results were compared with experimental results obtained by compression tests. The experimental/numerical correlation confirmed the validity of the FEM “beam element – based” lattice structure that could be applied to different solid shapes.

Keywords: 3D printing | Directional orientation | Finite element analysis (FEA) | Mechanical testing | Microstructure

[32] Cappetti N., Naddeo A., A survey of methods to detect and represent the human symmetry line from 3D scanned human back, Lecture Notes in Mechanical Engineering, 0, 799-809, (2017). Abstract

Abstract: Abstract This paper proposes a review of the methods to detect and represent the human symmetry line. In the last years, the development of 3D scanners has allowed to replace the traditional techniques (marking based methods) with modern methodologies that, starting from a 3D valid discrete geometric model of the back, perform the posture and vertebral column detection based on a complex processing of the acquired data. The purpose of the paper is a critical d iscussion of the state of the art in order to highlight the real potentialit ies and the limitations still present of the most important methodologies proposed for human symmetry line detection.

Keywords: Anatomical landmarks | Back shape analysis | Posture prediction | Rasterstereography | Symmetry line

[33] Naddeo A., Vallone M., Cappetti N., Califano R., Di Napoli F., Ergonomic-driven redesign of existing work cells: The “Oerlikon Friction System” case, Lecture Notes in Mechanical Engineering, 0, 1197-1207, (2017). Abstract

Abstract: The application of ergonomic principles to the design of processes, workplaces and organizations is not only a way to respond to legal requirements but also an indispensable premise for any company seeking to pursue a business logic. This paper shows a cheap and effective method to perform the ergonomic analysis of worker postures in order to optimize productivity and obtain the highest ergonomic ratings. Evaluations were performed for the 5°, 50° and 95° percentiles according to OCRA and NIOSH methods of biomechanical risk assessment. The results highlighted the need for improvements. A virtual simulation using DELMIA® software and the use of workers’ checklists drew attention to problems causing significant physical stress, as identified by ergonomic tools. An ergonomic/ comfort-driven redesign of the work cell was carried out, and CaMAN® software was used to conduct a final comfort-based analysis of the worst workstation in the work cell.

Keywords: Comfort rating | Ergonomic evaluation | NIOSH analysis | OCRA Index | Redesign

[34] Cappetti N., Naddeo A., Califano R., Vallone M., Using axiomatic design to identify the elements that affect the evaluation of comfort/discomfort perception, Advances in Intelligent Systems and Computing, 487, 235-248, (2017). Abstract

Abstract: Knowledge about the effects of primary factors on comfort level is useful in Human-Machine-Interface (HMI) design. The study and the mathematical modeling of these effects strongly depends on cross relations between the different kinds of comfort, the primary factors’ effects, and the modifiers’ actions. Starting from a sizeable bibliographic analysis, this paper describes a study, based on the axiomatic design approach, of the interactions between the results, factors, and modifiers in comfort/discomfort evaluation. The modifiers’ influence was determined by measuring the changes in information content. This study allowed us to validate and optimize our equation for the perceived “level of well-being” in order to better study the perception of comfort/discomfort in HMI.

Keywords: Axiomatic design | Comfort rating | Discomfort | Evaluation criteria | Perception

[35] Cappetti N., Naddeo A., Villecco F., Fuzzy approach to measures correction on Coordinate Measuring Machines: The case of hole-diameter verification, Measurement: Journal of the International Measurement Confederation, 93, 41-47, (2016). Abstract

Abstract: In this paper we analyze the capabilities of a routine, based on Fuzzy logic, for elaborating a data set coming from a CMM (Coordinate Measuring Machine). We will show how to obtain, during holes measuring, the best measure, so that the approximation error is minimized. Moreover the CMM on-board software can elaborate these data and select the mathematical representation of the stored data, by identifying quotes, measures, axes, diameters, tolerances and so on. Information on measured parts is usually elaborated by an algorithm based on the least square squared error method, in order to evaluate the good shape of the hole; our purpose is to propose a new kind of approach, based on the Inferential Fuzzy system method, both to reduce the number of measured points, and to obtain the same accuracy. Our approach enables to measure the holes with a number of points lower than those usually needed for the CMM software. Thus time spent for obtaining a good measure is significantly reduced.

Keywords: Accuracy | Coordinate Measuring Machine | Fuzzy inference | Holes measurement | Precision

[36] Cappetti N., Naddeo A., Naddeo F., Solitro G.F., Finite elements/Taguchi method based procedure for the identification of the geometrical parameters significantly affecting the biomechanical behavior of a lumbar disc, Computer Methods in Biomechanics and Biomedical Engineering, 19(12), 1278-1285, (2016). Abstract

Abstract: Abstract: The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the ‘Taguchi orthogonal array’ to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model.

Keywords: geometrical parameters | intervertebral disc | Spine | subject-specific finite element models | Taguchi method

[37] Trapanese S., Naddeo A., Cappetti N., A Preventive Evaluation of Perceived Postural Comfort in Car-Cockpit Design: Differences between the Postural Approach and the Accurate Muscular Simulation under Different Load Conditions in the Case of Steering-Wheel Usage, SAE Technical Papers, 2016-April(April), (2016). Abstract

Abstract: The evaluation of perceived comfort inside a car during the early stages of the design process is still an open issue. Modern technologies like CAE (Computer Aided Engineering) and DHM (Digital Human Modeling) already offer several tools for a preventive evaluation of ergonomic parameters for car drivers using detailed CAD (Computer Aided Design) models of car interiors and by a MBS (multi-body-system) solver for evaluating movements and interactions. Such evaluations are, nonetheless, not sufficient because the subjectivity of comfort perception is due to factors that are very difficult to evaluate in the early stage of design. Physical prototypes are needed and these are often too expensive to be realized. In the last 30 years, several researchers have tried to develop methods to objectivize comfort performance but most of these methods are based on questionnaires, market research, or physiological and biomechanical analyses, and need devices or interactions that modify perceived comfort. Recently, the authors of this study developed a software tool named CaMAN® for postural comfort evaluations of upper limbs. The software employs a static analysis of human joints in a working environment (the car cockpit is assumed to be a working environment). Some software, like AnyBody™, allows evaluations of the muscular efforts made during body actions. In the literature, it is possible to find several papers such as Na et al. [26] and Telfer et al. [40] that demonstrate a correlation between muscular effort and perceived comfort. Empirical evidence suggests that better comfort is related to lower muscular activity. This paper shows the results obtained from numerical and experimental analyses using AnyBody™ and CaMAN®. Simulations of the static and dynamic behaviors of a car driver using a steering wheel are performed. The results show the differences between preventive analyses of perceived comfort that are made with and without an applied load for a subject in the fiftieth percentile. This paper shows the results obtained from numerical and experimental analyses using AnyBody™ and CaMAN®. Simulations of the static and dynamic behaviors of a car driver using a steering wheel are performed. The results show the differences between preventive analyses of perceived comfort that are made with and without an applied load for a subject in the fiftieth percentile.

[38] Vallone M., Naddeo A., Cappetti N., Califano R., Comfort driven redesign methods: An application to mattresses production systems, Open Mechanical Engineering Journal, 9(1), 492-507, (2015). Abstract

Abstract: The definitions of methods and tools used to evaluate how workers perceive the comfort during their activities remains an “open” problem at this time. Many researchers have dealt with that problem in the last twenty years, focusing their efforts primarily on the automotive sector and on VDT workstation comfort. This paper analyzes how workers position themselves at workstations used in industrial processes that sew together the edges of mattresses. The aim of the analysis is to determine whether workers can position themselves in ways that allow them to carry out activities in simple and economical ways. The Strain Index was used to identify the most critical and risky work phases in order to evaluate workers' risk of biomechanical overload. The OCRA checklist was used to evaluate the overall risk level associated with repeated completions of the total cycle of work and to develop a virtual-postural analysis to evaluate workers' perceived levels of discomfort. For the virtual-postural analysis, DELMIA® software was used to virtually model a workstation, and records of activities and the postures associated with various repetitive actions were gathered in a non-invasive manner with cameras and video cameras. CaMAN® software developed by the researchers from the Department of Industrial Engineering in Salerno (Italy) was used to calculate comfort indexes. An analysis of the comfort indexes was used to make as the basis for suggestions to correct workers' postures and for plans to redesign the workstations in order to improve ergonomics and allow workers to perceive them as more comfortable.

Keywords: Comfort evaluation criteria | Digital human modeling | Ergonomics | Non-invasive postural analysis | Redesign

[39] Naddeo A., Cappetti N., D'Oria C., Proposal of a new quantitative method for postural comfort evaluation, International Journal of Industrial Ergonomics, 48, 25-35, (2015). Abstract

Abstract: In Human-Machine Interface (HMI) design, several parameters have to be correctly evaluated in order to guarantee a good level of safety and well-being of users (humans) and to avoid health problems like muscular-skeletal disease. ISO Standards give us a good reference on Ergonomics and Comfort: ISO 11228 regulation; it deals with qualitative/quantitative parameters for evaluating Postural Ergonomics, using a "Postural Load Index", in push/pull, in manual loads' lifting and carrying and in repetitive actions; those parameters can represent the Ergonomics level of examined posture. While bibliographic references suggest different methods to make ergonomic evaluation like RULA, LUBA and REBA, the state of the art about comfort/discomfort evaluation shows the need of an objective method to evaluate "effect in the internal body" and "perceived effects" in several schemes of comfort perception like Moes', Vink & Hallback's and Naddeo & Cappetti's ones; postural comfort is one of the aspect of comfort/discomfort perception and this paper proposes a new quantitative method for evaluating this aspect of comfort, based on anthropometric parameters and upper limbs posture. The target of this paper is to present and test a "general purpose" method of comfort-measurement that can be applied to different industrial cases: in workspace environments, in automotive passenger compartments, in aeronautic cockpit or in industrial assembly lines. Relevance to industry: The method presented in this paper may allow industrial designers to provide an assessment of products' perceived comfort in the early stage of the product development process by making a posture-based quantitative evaluation; it also allows designers to make a comfort driven redesign of existing products' configuration for improving and innovating them.

Keywords: Comfort evaluation | Ergonomics | Industrial design | Postural analysis

[40] Naddeo A., Cappetti N., Califano R., Vallone M., The Role of Expectation in Comfort Perception: The Mattresses’ Evaluation Experience, Procedia Manufacturing, 3, 4784-4791, (2015). Abstract

Abstract: What are the new trends in research for comfort evaluation and the objective and predictive techniques for quantifying and qualifying comfort perception by humans? This paper has attempted to answer this question in a wide literature review, whereby it is possible to highlight many partial aspects that have been studied successfully. Just a few researchers [1–3] have studied the problem of comfort perception and evaluation under a wider point of view. Nevertheless, some aspects seem not to have yet been taken into account. In a previous paper, the authors extended the Vink–Hallbeck model to build a comfort perception/evaluation matrix in which four kinds of comfort related to different humans’ perception were studied and linked to the whole environment's characteristics. In the resultant perception-scheme and in the proposed “fusion rule” (for different kinds of perceived comfort/discomfort), one aspect that played a fundamental role in the final comfort/discomfort perception/evaluation was expectation. Expectation due to preconceived data (acquired or formed in the users’ minds) and the influence of the working environment, can act in terms of additive or subtractive factor in the comfort experience by altering the final comfort/discomfort perception and changing the subjective comfort/discomfort evaluation. This paper presents the results of expectation influence analysis on comfort evaluation. Using the placebo effect, authors conducted a wide experimental test with a wide sample of users, asking them to use and evaluate two identical mattresses that were dressed and described as two different products (the first one as a very cheap mattress and the second one as a high-level and expensive mattress). Differences between subjective evaluations have been statistically processed and correlated to anthropometric parameters to individuate and understand the role of expectation.

Keywords: Cognitive | Comfort evaluation | Expectations | Mattress | Physiological and environmental comfort | Postural

[41] Cappetti N., Perrella M., Salvati A.G., About confusion among products and manufacturers, International Journal of Applied Engineering Research, 10(20), 41294-41302, (2015). Abstract

Abstract: The boundary between a product copied and a new product, with the same functions of the existing ones, is difficult to establish, since both are based on previous common technical knowledge and the need to satisfy the consumer perception of the product. Starting from the analysis of a case study in the matter of legal challenges concerning alleged patent infringement, some considerations on this topic and patterns of new products development in established markets are presented. It emerges that technical knowledge combined with market and managers requirements and constraints induce similar products design. This is why companies developing new products based on existing concepts often face a lawsuit, moved from that competitor whose market is unjustly threatened.

Keywords: Case based reasoning | Innovation | Perception | Products confusion | Similarity judgments

[42] Apostolico A., Cappetti N., D'Oria C., Naddeo A., Sestri M., Postural comfort evaluation: Experimental identification of Range of Rest Posture for human articular joints, International Journal on Interactive Design and Manufacturing, 8(2), 109-120, (2014). Abstract

Abstract: In this paper we introduce and describe a new concept in human-measurements operation that seems to be very useful for comfort evaluation: the Range of Rest Posture (RRP). Our study is focused on the identification of RRP -inside the comfort range of motion (CROM)-for the following human joints: neck, shoulder, elbow, wrist and ankle. Method used is based on a wide experimental work on 85 healthy individuals (43 males and 42 females) ranging in age from 20 to 30 year. The main target of this work is the experimental definition of CROM and identification of RRP; Experimental data has been processed by statistical methods for identifying the best statistical distribution in order to fit experimental data. Main result is the identification of RRP in CROM of main human joints involved in upper and lower limbs movements. In RRP weve found several maximum level of comfort positions in human postures: those position seems to be one of the most important information in comfort evaluation analysis. The state of the art about comfort/discomfort evaluation shows the need of an objective method to evaluate effect in the internal body and perceived effects in Moes (Contemporary ergonomics. Taylor & Francis, London, 2005) and Vink and Hallback (Appl Ergon 43:271-276, 2012) scheme of comfort perception; postural comfort is one of the aspect of comfort/discomfort perception and this paper helps to put a piece in the puzzle of posture evaluation. On the basis of papers results, a comfort evaluation method can be developed using RRP, CROM and building a composition rule that takes into account also lumbar comfort and H-point. Our work does not use ROM and CROM values coming from literature because each of these values has been experimentally identified. © 2013 Springer-Verlag France.

Keywords: Comfort evaluation | Human joints | Range of motion | Rest Posture

[43] Naddeo A., Cappetti N., Ippolito O., Dashboard reachability and usability tests: A cheap and effective method for drivers' comfort rating, SAE Technical Papers, 1, (2014). Abstract

Abstract: General comfort may be defined as the "level of well-being" perceived by humans in a working environment. The state-of-the-art about evaluation of comfort/discomfort shows the need for an objective method to evaluate the "effect in the internal body" and "perceived effects" in main systems of comfort perception. In the early phases of automotive design, the seating and dashboard command can be virtually prototyped, and, using Digital Human Modeling (DHM) software, several kinds of interactions can me modeled to evaluate the ergonomics and comfort of designed solutions. Several studies demonstrated that DHM approaches are favorable in virtual reachability and usability tests as well as in macro-ergonomics evaluations, but they appear insufficient in terms of evaluating comfort. Comfort level is extremely difficult to detect and measure; in fact, it is affected by individual perceptions and always depends on the biomechanical, physiological, and psychological state of the tester during task execution. These parameters cannot be modeled using software and instead have to be tested on physical models. A seating buck is often used to prototype a driver's seat, and virtual, mixed, and augmented reality devices help designers to improve ergonomics and comfort of a human-machine interface (HMI). In such environments, both postural and cognitive comfort can be evaluated, but often, testers' opinions are affected by devices, their interaction with designers, and especially, posture analysis systems. One solution to this kind of perception alteration can be found in non-invasive acquisition methods, such as acoustic, magnetic, or optical methods. Each has its own advantages and disadvantages, but all share the same characteristics: they are expensive and difficult to calibrate and use. This paper presents a new method for objectifying and evaluating postural and cognitive comfort levels based on human posture analysis and a questionnaire to evaluate cognitive performance. The posture acquisition method employs commercial low-cost cameras on tripods. The comfort evaluation methods, previously developed at the University of Salerno, are based on several experimental test campaigns, statistical processing, and biomedical studies. The method was tested in terms of reachability and usability for automotive drivers and was performed in a B-segment car (FIAT Grande Punto). A sensitivity analysis was performed to correlate the low resolution of the photographic acquisition with the consequent errors in the comfort evaluation. Posture acquisition errors were analyzed using DHM (DELMIA) software. Copyright © 2014 SAE International.

[44] Naddeo F., Cappetti N., Naddeo A., Automatic versatile parametric procedure for a complete FEM structural analysis of composites having cylinder-shaped reinforcing fibres, Computational Materials Science, 81, 239-245, (2014). Abstract

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

[45] Naddeo A., Cappetti N., Califano R., Vallone M., Manual assembly workstation redesign based on a new quantitative method for postural comfort evaluation, Applied Mechanics and Materials, 459, 368-379, (2013). Abstract

Abstract: Main purpose of this work is to show how easy and economics an ergonomic/comfort based approach, in re-design a manual assembly workplace, can be; authors, using a new comfort/ergonomic evaluation criterion, analyzed a workstation and identified the critical issues under ergonomic/comfort point of view and finally gave several guidelines to re-design the workplace, implementing minor modification, and improve work-safety, work-quality and productivity. The postural analysis was performed by non-invasive and especially inexpensive methods, based on cameras and video-recorder use and by photogrammetric analysis; DELMIA® DHM software has been used to perform all simulations; comfort analysis was performed by the software developed by researchers of Departments of Industrial Engineering of Salerno: CaMAN®. The test case is an automatic assembly machine that has been modeled and used for virtual postural analysis. Main results of this work can be found in a very good numerical/experimental correlation between acquired/simulated postures and real ones, and on the powerful use of an objective comfort evaluation method, based on biomechanics and posture analysis, for giving to designers the guidelines to re-design a workplace and a work-cycle. This kind of approach seemed to be very powerful in re-designing the work-place and in re-scheduling the work time-sheet because it allowed to improve an ergonomic corrective action with minor costs for company. Obtained results demonstrated the validity of re-design hypotheses through the increase of all comfort indexes and the improvement of workstation/operator productivity. © (2014) Trans Tech Publications, Switzerland.

Keywords: Comfort evaluation criteria | Digital human modeling | Ergonomics | Not-invasive postural analysis | Re-design

[46] D'Agostino V., Cappetti N., Pisaturo M., Senatore A., Improving the engagement smoothness through multi-variable frictional map in automated dry clutch control, ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 11, 9-19, (2012). Abstract

Abstract: An Automated Manual Transmission (AMT) is directly derived from a manual one through the integration of actuators; then, development and production costs are generally lower than other automatic transmissions, while the reliability and durability are at highest level. For high class sport cars, vehicle dynamic performances and driving quality can be strongly improved with respect to automatic transmissions [1]. AMTs systems are generally constituted by a dry or wet clutch assembly and a multi-speed gearbox, both equipped with electro-mechanical or electro-hydraulic actuators, which are driven by a control unit, the transmission control unit (TCU). The operating modes of AMTs are usually two: semiautomatic or fully automatic. In both cases, after the gear shift command, the TCU manages the shifting steps according to current engine regime, driving conditions and selected program. In this transmission type the quality of the vehicle propulsion as perceived by the driver is largely dependent on the quality of the control strategies. Furthermore, sensitivity analyses on control schemes for AMTs have shown that uncertainties in clutch torque characteristic can severely affect the performance of the clutch engagement: modeling in detail the torque transmitted by the specific clutch architecture is a crucial issue in order to design robust engagement control strategies [2, 3 and 4]. This paper aims at investigating the engagement performance of an actuated dry clutch by taking into account the inference of the pressure on the facing materials and the sliding speed. In fact, according to literature outcomes [5], the friction coefficient after a first rising behavior with the sliding speed shows an asymptotic value for a typical clutch facing; the same material exhibits a nearly linear dependence of the friction coefficient on the pressure. The simulations consider: reduced-order dynamic system for simulation of passenger car driveline, control algorithm, experimental maps of the n-D clutch transmission characteristic, and gear shift maneuvers in different operating conditions. The outcome of this analysis could provide valuable issues for designers of automated clutches and control engineers to overcome the well known poor engagement performances of open loop motion strategy of the throwout bearing where cost reason and complexity don't permit the use of displacement sensor. Copyright © 2012 by ASME.

Keywords: Automated manual transmissions | Dry clutch transmissibility | Frictional coefficient map | Sliding speed | Temperature effect

[47] Cappetti N., Pisaturo M., Senatore A., Modelling the cushion spring characteristic to enhance the automated dry-clutch performance: The temperature effect, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 226(11), 1472-1482, (2012). Abstract

Abstract: The cushion spring plays an important role in an automotive dry-clutch system. It strongly influences the clutch torque transmission from the engine to the driveline through its non-linear load-deflection curve. Therefore, knowledge of the cushion spring compression behaviour is crucial to improve the gearshift performance in an automated manual transmission. Furthermore, the cushion spring compression behaviour is influenced by the temperature because of the frictional heat generation of the clutch facings with the flywheel and the pressure plate surfaces during the engagement phase. In this paper an analysis of the load-deflection curve, taking into account the thermal load to which it is subjected, of a typical passenger car cushion spring is proposed. Six temperatures, in addition to room temperature, were analysed to investigate how the cushion spring load-deflection curve depends on the temperature. © 2012 IMechE.

Keywords: automated manual transmissions | Cushion spring | dry clutch | thermal effects

[48] Cappetti N., Pisaturo M., Senatore A., Load-deflection curve sensitivity to main shape parameters in a dry clutch cushion spring, Proceedings of the 7th International Conference on Engineering Computational Technology, (2010). Abstract

Abstract: The cushion spring is an important component of an automotive dry clutch system. In fact, it influences strongly the clutch torque transmission from engine to driveline. Therefore a study on the cushion spring compression behaviour is crucial to improve the gearshift performance in automated manual transmission. In this paper a sensitivity analysis on the load-deflection curve of a typical passenger car cushion spring is proposed. Four geometrical parameters of the main shape of the cushion spring have been analyzed and for each one the influence on the static characteristic has been shown. © 2010 Civil-Comp Press.

Keywords: Cushion spring | Dry clutch | Sensitivity analysis

[49] Cappetti N., Donnarumma A., Naddeo A., Russo L., Design of experiment about foam CF45 for pedestrian safety in car design, Journal of Materials Processing Technology, 175(1-3), 77-82, (2006). Abstract

Abstract: A statistical approach based on the variance analysis allows to appraise the influence of the foam that covers leg impactors on results of the tests required by European New Car Assessment Program [EuroNCAP, Pedestrian Testing Protocol, Rel. 3.1.1, Gennaio, 2002] and ACEA (European Automobile Manufacturers Association) for the safety of the pedestrians in case of accident. Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the human femur: it has a very complicated system to simulate the whole bone-flesh-skin apparatus and, in particular, has two layers of special Confor™ Foam CF45 Blue that has the same mechanical behaviour of human flesh; we have made a dynamic characterization of that foam at medium and high impact velocity; in order to simulate the whole leg impactor, in PamCrash environment, using the ESI formulation of the skin and using the results of characterization of all other elements with experimental tests. Experimental data coming from tests on foam have a medium value and dispersion around the mean; that dispersion can affect significantly the results of final simulation. So we have applied several statistical methods in order to optimize the final simulation results. This analysis is a part of a more complex design of experiment that analyse the difficulties when we simulate, using finite element method (FEM) simulation, the impact pedestrian-car. In problematic that is complex and not linearly influenced by many factors even a numerical simulation could be improved and optimised by statistic techniques. © 2005 Elsevier B.V. All rights reserved.

Keywords: Confor Foam | Design of experiment | Pedestrian safety

[50] Naddeo A., Cappetti N., Pappalardo M., Donnarumma A., Fuzzy-logic application in the structural optimisation of a support plate for electrical accumulator in a motor vehicle, Journal of Materials Processing Technology, 120(1-3), 303-309, (2002). Abstract

Abstract: In this paper, we analyse the design of a support plate for the accumulator of an electric motor vehicle. The support is an integral part of motor vehicle chassis. Therefore, geometrical configuration and boundary conditions require careful optimisation research of both function and structural behaviour, since lightness and dimension problems in the presence of dynamic stresses due to external factors have to be considered. Since these factors are complex and not homogeneous, the problem requires multi-criteria analysis. The presence of factors that are not precisely computable calls for fuzzy-logic application to optimisation problems, because fuzzy-logic is non-standard logic, particularly suitable for making choices in structural design. In plate optimisation, in fact, not numerically quantifiable characteristics such as a part's workability, numerically determinable structural values such as stresses and strains, and analytically calculable properties such as weight come into play. These four parameters become the domain of fuzzy membership functions, by which we will extract membership grade values (co-domain). Design variables (domain) are plate thickness, ashlar's number on the plate and stiffening ashlar's depth. In our research, we characterise fuzzy correlation between parameters and required characteristics in order to determine, according to non-standard logics, the best topological configuration which corresponds to the optimisation of individualised characteristics in conformity with design constraints. Results show value improvement in stress and strain in comparison with the not yet optimised plate and small reduction in workability, whereas the mass is almost the same. © 2002 Published by Elsevier Science B.V.

Keywords: Decision making | Fuzzy logic | Structural optimisation

[51] Donnarumma A., Cappetti N., Pappalardo M., Santoro E., A fuzzy design evaluation based on taguchi quality approach, Proceedings of the 2nd International Conference on Intelligent Processing and Manufacturing of Materials, IPMM 1999, 1, 185-189, (1999). Abstract

Abstract: A fuzzy method to handle vagueness and imprecision in the description of requirements for multi-attribute decision making (MADM) problem is presented. This method is applied to design of an apron conveyors to collect and transfer scraps. The aggregation function for the overall evaluation is obtained utilising the Taguchi loss functions.

[52] Cappetti N., Santoro E., Application of computer visualization for solving a mechanical design by fuzzy set, Proceedings of the IEEE Symposium on Information Visualization, 69-75, (1998). Abstract

Abstract: A computer visualization application has been presented for fuzzy evaluation of windscreen wiper systems which must satisfy several requirements. Some requirements are modelled by fuzzy sets and a compensating arithmetic mean is utilized for computing an overall performance. A computer animation of wiper mechanism motion and rainfall is shown, which enables to experts, drivers and passengers to evaluate the degree of satisfaction and correctness of judgements. This fuzzy evaluation approach is illustrated by considering five `subjective' requirements (driver and passenger visibility, wiped surface, visibility and trouble sensations), and for three design alternatives (traditional single and double wiped systems and variable course system) the results are shown.