[Elenco soci]

Gherardini Francesco

Ricercatore TD(B)

Università degli Studi di Modena e Reggio Emilia

Sito istituzionale
SCOPUS ID: 57150736400
Orcid: 0000-0002-9275-4314

Pubblicazioni scientifiche

[1] Bici M., Gherardini F., de Los Angeles Guachi-Guachi L., Guachi R., Campana F., Convolutional Neural Network for Background Removal in Close Range Photogrammetry: Application on Cultural Heritage Artefacts, Lecture Notes in Mechanical Engineering, 780-792, (2023). Abstract

Abstract: Post-processing pipeline for image analysis in reverse engineering modelling, such as photogrammetry applications, still asks for manual interventions mainly for shadows and reflections corrections and, often, for background removal. The usage of Convolutional Neural Network (CNN) may conveniently help in recognition and background removal. This paper presents an approach based on CNN for background removal, assessing its efficiency. Its relevance pertains to a comparison of CNN approaches versus manual assessment, in terms of accuracy versus automation with reference to cultural heritage targets. Through a bronze statue test case, pros and cons are discussed with respect to the final model accuracy. The adopted CNN is based on the U-NetMobilenetV2 architecture, a combination of two deep networks, to converge faster and achieve higher efficiency with small datasets. The used dataset consists of over 700 RGB images used to provide knowledge from which CNNs can extract features and distinguish the pixels of the statue from background ones. To extend CNN capabilities, training sets with and without dataset integration are investigated. Dice coefficient is applied to evaluate the CNN efficiency. Results obtained are used for the photogrammetric reconstruction of the Principe Ellenistico model. This 3D model is compared with a model obtained through a 3D scanner. Moreover, through a comparison with a photogrammetric 3D model obtained without the CNN background removal, performances are evaluated. Although few errors due to bad light conditions, the advantages in terms of process automation are consistent (over 50% in time reduction).

Keywords: Close range photogrammetry | CNN | Cultural heritage preservation | MobilenetV2 | Reverse engineering | U-Net

[2] Galati N., Gherardini F., Guaitoli C., Vergnano A., Simulation-Based Design of Reconfigurable Moulds for Injection Overmoulding, Lecture Notes in Mechanical Engineering, 1159-1171, (2023). Abstract

Abstract: The injection moulding process enables the production of complex shaped parts, thanks to the accurate kinematics and the tight tolerances of the mould. This process is suitable for large batch production, leading to reduced single part costs, but involves high initial investments. The life of a mould can be increased by exploiting reconfigurable cavity inserts. So, a design method has been conceived for reconfigurable injection moulds by integrating Design for Assembly and Computer Aided Engineering techniques. From the early phases of a systematic design approach, the simulation models are configured with the different geometries as requested by design specifications. The mould inserts are designed with standard features in order to be quickly changed. A case study on a reconfigurable mould for the overmoulding of polymer wheels to be produced in different sizes is presented. The simulations with Moldex3D software are finally compared with the experimental data from the actual production.

Keywords: Computer Aided Engineering | Design for Assembly | Injection Moulding | Reconfigurable mould

[3] Gherardini F., Sirocchi S., Systematic integration of 2D and 3D sources for the virtual reconstruction of lost heritage artefacts: the equestrian monument of Francesco III d’Este (1774–1796, Modena, Italy), Heritage Science, 10(1), (2022). Abstract

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

[4] Petruccioli A., Gherardini F., Leali F., Correction to: Assessment of close-range photogrammetry for the low cost development of 3D models of car bodywork components (International Journal on Interactive Design and Manufacturing (IJIDeM), (2022), 16, 2, (703-713), 10.1007/s12008-022-00865-6), International Journal on Interactive Design and Manufacturing, 16(2), 715-716, (2022). Abstract

Abstract: Authorswould like to correct Figure 1 and Image credits with the updated version. The corrected version of Figure 1 and Image credits updated here. The original article has been corrected.

[5] Petruccioli A., Gherardini F., Leali F., Assessment of close-range photogrammetry for the low cost development of 3D models of car bodywork components, International Journal on Interactive Design and Manufacturing, 16(2), 703-713, (2022). Abstract

Abstract: Close-range photogrammetry (C-RP) is a widespread and efficient technology to obtain digital models of physical objects. Typical limitations as sharped geometry, shiny surface finishing and light conditions can be overcome by using high-end equipment, which results in increased costs and requires specific skills in human operators. This paper aims to investigate whether a low-cost and simplified approach to C-RP makes it suitable for the 3D acquisition of bodywork components and similar free-form artefacts, as an affordable alternative to 3D scanning in fields where a lower value of accuracy is required. Hence, two commercial C-RP software were used to 3D capture handcrafted car body panels and compare the C-RP models using a 3D scan as a reference within an inspection software. Two case studies are considered: a 1:5 scale model of the front bonnet of a Ferrari 250 Testa Rossa from 1958 and a head lamp housing of a Ferrari 275 GTB from 1962. Considering the complexity of double curvature surfaces and the reflection due to material and surface treatment, both these artefacts require some pre-processing operations and an adequate set-up to perform image acquisition. These case studies represent a relevant application for the field of classic vehicle restoration, where C-RP could be a promising technique to support panel beaters and craftsmen during rebuilt operations of masks and bodywork spare parts of high-end historic cars.

Keywords: 3D capturing | 3D digital model | car body panel | Classic vehicle restoration | Close-range photogrammetry | Geometric inspection

[6] Garlaschelli G., Gherardini F., Malagola S., Leali F., Investigation of Warpage and Tolerances in Injection Moulding Components Based on Simulation and Experimental Validation, Lecture Notes in Mechanical Engineering, 342-353, (2022). Abstract

Abstract: This paper presents a systematic approach to model and simulate the influence that the variation of process parameters has on the final quality of an injection moulded component. In the first phase, we define a multi-steps procedure to develop a reliable digital model of the injection moulding process by the fine-tuning of the part cavity and the mould elements (e.g. detail simplification, discretization and mesh density, elements modelling, etc.) using real data as validation. In the second phase, we investigate the correlation between selected process parameters and the final tolerances of the moulded component, based on a Design of Experiments. As a case study, we selected the body of a mass airflow sensor for an automotive high performance engines, made of polybutylene terephthalate reinforced with glass-fibre, which presents roundness issues on functional features. The effects of the injection velocity and packing pressure on the deformation of the component are investigated, identifying the best combination of their values that leads to compliance with the roundness tolerances on its functional features. The injection moulding Computer Aided Engineering (CAE) software Moldex3D (CoreTech) is used to run the simulations, and the results are finally validated by comparing the experimental data obtained from the injection moulding machine that produces the component.

Keywords: Design of Experiments | Injection moulding | Simulation-based design approach | Tolerances | Warpage

[7] Tagliazucchi G., Marchi G., Gherardini F., Leali F., The multiple roles of universities in U-I collaborations: The case of Emilia–Romagna motor vehicle industry, Journal of Engineering and Technology Management - JET-M, 62, (2021). Abstract

Abstract: This paper investigates the development of collaboration modes between university and local industry, within a regional system having a diffused innovation process. As a case study, we analyse into an appreciative framework the roles of a medium-sized university as producer of knowledge, intermediary organisation and regional orchestrator over time, ultimately assuming a leading role in two specific university-industry programmes supporting the motor vehicle industry of Emilia–Romagna (IT). The paper contributes to the University-Industry stream of research by identifying the factors and mechanisms underpinning the evolution of university's role in its collaboration with local industry, by the time assuming a leading and central role in spreading innovative technology into the regional system. Our findings provide managerial and policy makers contributions, and could be extended to other similar medium-tech industry for supporting diffusion of knowledge and innovation processes.

Keywords: Academic engagement | Automotive industry | Regional innovation system | Technology transfer

[8] Ghosh M., Obaidullah S.M., Gherardini F., Zdimalova M., Classification of geometric forms in mosaics using deep neural network, Journal of Imaging, 7(8), (2021). Abstract

Abstract: The paper addresses an image processing problem in the field of fine arts. In particular, a deep learning-based technique to classify geometric forms of artworks, such as paintings and mosaics, is presented. We proposed and tested a convolutional neural network (CNN)-based framework that autonomously quantifies the feature map and classifies it. Convolution, pooling and dense layers are three distinct categories of levels that generate attributes from the dataset images by introducing certain specified filters. As a case study, a Roman mosaic is considered, which is digitally reconstructed by close-range photogrammetry based on standard photos. During the digital transformation from a 2D perspective view of the mosaic into an orthophoto, each photo is rectified (i.e., it is an orthogonal projection of the real photo on the plane of the mosaic). Image samples of the geometric forms, e.g., triangles, squares, circles, octagons and leaves, even if they are partially deformed, were extracted from both the original and the rectified photos and originated the dataset for testing the CNN-based approach. The proposed method has proved to be robust enough to analyze the mosaic geometric forms, with an accuracy higher than 97%. Furthermore, the performance of the proposed method was compared with standard deep learning frameworks. Due to the promising results, this method can be applied to many other pattern identification problems related to artworks.

Keywords: Convolutional neural networks | Cultural heritage | Deep learning algorithm | Image-based reconstruction | Pattern classification

[9] Bastai V., Cavani A., Gherardini F., Orsini G., The Struttura Reticolare Acentrata, a Design Strategy for Spatial Organization, Nexus Network Journal, 23(1), 129-147, (2021). Abstract

Abstract: The Non-centred Reticular Structure is a modular pattern developed by Cesare Leonardi (Modena, Italy, 1935) from 1983, the result of research into spatial and urban planning focusing on trees. It is a model of spatial organization seeking a balance between the spaces of people and those of trees, reconciling and promote all living forms. The Structure consists of a primary pattern of 23 irregular polygons defining the areas belonging to each stakeholder in the spatial organisation: humans, plants, animals. The sides of the polygon constitute a network of nodes (vertices) and connecting rods. The pattern may evolve in space and time, combining biomimicry and geometry, and adapts to different contexts through metamorphosis and deformations. The Structure was applied to ‘Bosco Albergati’ Park (Modena, Italy) which, 30 years after planting, represents an example of spatial organisation imitating nature. This paper presents the Structure as a tool supporting the designer in the spatial organisation of the functional design elements, and investigates its relevance in the design of current green projects.

Keywords: Biomimicry | Design method | Modular pattern | Spatial organisation | Struttura reticolare acentrata (non-centred reticular structure) | Tree

[10] Petruccioli A., Gherardini F., Panari D., Leali F., Computer-Aided Tolerancing Analysis of a High-Performance Car Engine Assembly, Lecture Notes in Mechanical Engineering, 121-127, (2021). Abstract

Abstract: This paper proposes the analysis of the tolerances (values, types, datum) and their effects on a mechanical assembly, as a high-performance car engine, by means of a Computer-Aided Tolerancing software. The 3D tolerance stack-ups are investigated to assess the fulfillment of the functional requirements as well as the performance specifications of the assembly. Moreover, after identifying the tolerances that mainly affect the product variability, we finally propose some corrective actions on the tolerances and assess their functional allocation, tightening or relaxing their values, ensuring assemblability and cost reduction.

Keywords: Automotive assembly | Car engine | Computer-Aided Tolerancing | Geometric dimensioning and tolerancing (GD&T) | Tolerance analysis method

[11] Bici M., Gherardini F., Campana F., Leali F., A preliminary approach on point cloud reconstruction of bronze statues through oriented photogrammetry: The “Principe Ellenistico” case, IOP Conference Series: Materials Science and Engineering, 949(1), (2020). Abstract

Abstract: Close-Range Photogrammetry is a widespread and efficient technique in the 3D acquisition of artefacts, particularly in fields like Cultural Heritage. Despite this wide usage, also due to a convenient quality/cost ratio, it shows some limitations due to light conditions as well as the artefact surface finishing. In this paper, we would like to report the assessment of a photogrammetry approach to 3D capture metal reflective surfaces, such as bronze, which is a widely used material in ancient statues. To this aim, we propose a photogrammetry workflow based on systematic steps capable of overcome some of the main issues of reflective surfaces. To validate this approach, the developed 3D model is compared to a more accurate model of the same artefact, obtained with a 3D scanner. As a case study, we selected the Principe Ellenistico, an ancient bronze statue conserved in the Museo Nazionale Romano (Rome, Italy), of which a photogrammetric model is firstly developed and then compared to the scanned one.

Keywords: 3D acquisition | Bronze statue | Close-Range Photogrammetry | Principe Ellenistico | Systematic approach

[12] Dalpadulo E., Gherardini F., Pini F., Leali F., Integration of topology optimisation and design variants selection for additive manufacturing-based systematic product redesign, Applied Sciences (Switzerland), 10(21), 1-13, (2020). Abstract

Abstract: The development of additive manufacturing allows the transformation of technological processes and the redesign of products. Among the most used methods to support additive manufacturing, the design can be optimised through the integration of topology optimisation techniques, allowing for creating complex shapes. However, there are critical issues (i.e., definition of product and process parameters, selection of redesign variants, optimised designs interpretation, file exchange and data management, etc.) in identifying the most appropriate process and set-ups, as well as in selecting the best variant on a functional and morphological level. Therefore, to fully exploit the technological potentials and overcome the drawbacks, this paper proposes a systematic redesign approach based on additive manufacturing technologies that integrate topology optimisation and a tool for selecting design variants based on the optimisation of both product and process features. The method leads to the objective selection of the best redesigned configuration in accordance with the key performance indicators (KPIs) (i.e., functional and production requirements). As a case study, the redesign of a medical assistive device is proposed, previously developed in fused filament fabrication and now optimised for being 3D printed with selective laser melting.

Keywords: Assistive device | Design for additive manufacturing | Design method | Design optimisation | Design variants selection | Redesign | Selective laser melting | Topology optimisation

[13] Rossi F., Pini F., Carlesimo A., Dalpadulo E., Blumetti F., Gherardini F., Leali F., Effective integration of Cobots and additive manufacturing for reconfigurable assembly solutions of biomedical products, International Journal on Interactive Design and Manufacturing, 14(3), 1085-1089, (2020). Abstract

Abstract: Collaborative robotics and additive manufacturing are two enabling technologies of the Industry 4.0 manufacturing paradigm. Their synergic integration requires novel and effective design approaches, aiming to the development of new reconfigurable solutions for customised processes and products. This work presents an integrated approach that exploits the capabilities of Cobots to mimic the repetitive and exhausting operator’s movements as well as the competitive advantages offered by additive manufacturing to realize tailored equipment. In particular, the case study shows the development of a customised device for the manipulation of biomedical components by means of a Cobot, which is introduced in a workstation to replace manual operations. Moreover, the flexibility and the effectiveness of a Cobot can be improved thanks to customised devices for gripping and pick-and-place operations based on a specific application. During the development phase, we simulated the assembly process, and tested different options. The final configuration, with conformal circuits and suction cups, can pick, manipulate and assembly the biomedical components, and thanks to a Fused Filament Fabrication technology is additively manufactured. In conclusion, this developed prototypal solution proves the real capabilities offered by integrating Cobots and additive manufacturing for the lean automation of a biomedical workstation.

Keywords: Additive manufacturing | Biomedical components | Collaborative robot | Design approach | Industry 4.0

[14] Bertoldi A., Gherardini F., Leali F., Implementation of a quality framework on the launch phase of an automated assembly line for top class automotive chassis, IOP Conference Series: Materials Science and Engineering, 836(1), (2020). Abstract

Abstract: Today the assembly lines of cars chassis are highly automated by robotic operations. Even in the top class automotive sector, the production of aluminium chassis involves numerous automated operations, such as TIG and MIG welding, riveting and gluing. This practice allows, on the one hand, to reduce time and costs, improve process repeatability and quality standards. On the other hand, it requires the quality improvement of the whole process (from supplied parts approval to welding reworks minimization). The industrialization phase of a new car chassis and the launch of its automated assembly line are particularly critical, even more if the line has already been designed and only minimally modifiable. Therefore, this paper proposes the implementation of a quality framework to manage the launch of an automated assembly line of a new aluminium chassis of top class cars, selected as a case study. The framework was implemented, aiming at improving the entire process quality, and finally validated by critically comparing the results obtained with those relating to models currently in production. Due to their importance to the final quality, we focused on the welding operations, which require actions both on process parameters and supplied parts approval (e.g. tolerances on parts end cuts). The new line shows a clear improvement compared to the past, with highly significant reduction of welding non-conformances, high quality level and lack of many critical issues of the previous lines thanks to corrective actions taken in the early process stages, during the pilot phase.

[15] Vergnano A., Gherardini F., Leali F., The systematic design of industrial products through design archetypes: An application on mechanical transmissions, Applied Sciences (Switzerland), 10(7), (2020). Abstract

Abstract: Engineering design is a knowledge intensive activity for both new and mature technical systems, such as mechanical transmissions. However, design knowledge is often transferred with conservative and unstructured approaches, although knowledge management would be of the utmost importance for modern industries. In this work, we introduce a design tool, called design archetype, for collecting and managing knowledge in systematic design processes. The design archetype addresses input design requirements for different design concepts, therefore, improving awareness of the design process by interactively modifying the design solution due to different input requirements. Finally, the design archetype updates the parameters of a first embodiment computer-aided design model of the concept. A method for the development of design archetypes is presented and applied to two case studies of mechanical transmission subassemblies. The results demonstrate the effectiveness of a systematic design method based on design archetypes stored in the company database.

Keywords: CAD-based tool | Design archetype | Knowledge-based engineering | Mechanical transmissions | Systematic design method

[16] Angelo L.D., Gherardini F., Stefano P.D., Leali F., Design for visual quality enhancement of artificial infrastructure facilities: An application to electricity pylons, Applied Sciences (Switzerland), 10(3), (2020). Abstract

Abstract: (1) Background: The visual impact of artificial infrastructures on natural landscapes generates a common negative perception in public opinion. However, as in the case of electrical energy, the increasing demand for power supply and its need for capillary distribution require the installation of new lines, commonly overhead lines with tall tower-like pylons. In most countries, this situation is faced with many attempts of solutions, as participatory workshops and design contests. Nevertheless, the solutions are usually not further developed into real structures due to many limitations (e.g., regulatory, safety, lack of feasibility). (2) Methods: This paper presents a systematic method for the design of tower-like pylons (e.g., electric ones) able to improve the visual quality on the landscape areas in which they will be installed. The method identifies a design strategy that advantageously exploits the inevitable visual impact of pylons on the landscape by integrating the symbolic morphology and the topologically optimized pylon structure from the earliest design phases. (3) Results: The resulting structure is designed in three steps. First, a concept is morphologically developed by integrating symbolic references to the landscape, environment, or cultural society. Second, the concept is topologically optimized, by reducing the structural weight and its visual impact, and respecting regulatory requirements. Third, the resulting structure is engineered and embodied into an industrially feasible layout. (4) Conclusions: The method is able to develop an original, brand new tower-like pylon integrating all the types of requirements, such as regulatory, industrial feasibility, and social components' needs. The resulting electricity pylon presents an enhanced visual quality according to the citizens' feedback.

Keywords: Electricity pylon | Integrated design method | Topology optimization | Visual impact improvement

[17] Gherardini F., Petruccioli A., Dalpadulo E., Bettelli V., Mascia M.T., Leali F., A methodological approach for the design of inclusive assistive devices by integrating co-design and additive manufacturing technologies, Advances in Intelligent Systems and Computing, 1131 AISC, 816-822, (2020). Abstract

Abstract: Additive Manufacturing is a widespread technology that may enhance product customization based on specific users’ needs, as in the case of assistive devices. Many chronic physical progressively disabling diseases, but also ageing, may cause severe limitations in daily life, which can be overcome by highly customized aids. Literature shows that the active involvement of the patient in the development of assistive devices through co-design allows for their greater therapeutic effectiveness and acceptance. Therefore, this paper proposes a methodological approach for the development of inclusive assistive devices to support daily activities in persons with disabling diseases of the upper-limb. The approach integrates co-design, standardized tools, and low- and high-tech prototyping techniques and tools, which lead to significant feedbacks from patients. The patients are encouraged to interact with conceptual prototypes through direct 3D CAD modelling and touch screen devices. Assessment tests highlight the suitability of the method to achieve the expected goals.

Keywords: Additive Manufacturing | Assistive device | Co-design | Hand pathologies | Inclusive method | Occupational therapy | Parametric modelling

[18] Vergnano A., Gherardini F., Petruccioli A., Bonazzi E., Leali F., Robust Parameter Analysis of Compliant Part Models for Computer Aided Tolerancing, Lecture Notes in Mechanical Engineering, 241-254, (2020). Abstract

Abstract: Sheet metal parts are widely used in automotive, aerospace, ship and consumer goods industries. The final dimensions of a sheet metal assembly result from the parts deformation, which in turn is affected by many variations in material, thickness and single parts dimensions. The tolerance analysis on sheet metal assemblies improve the knowledge about the process. Advanced simulations enable the optimization of product features, GD&T scheme and assembly process. Moreover, Variational Models of both the product and the assembly system enable to assess the sources of 3D error propagation from the different contributors. However, the simulation results are very affected by the modelling approach of critical components, such as the Fixture Systems. The present paper firstly introduces a strategy to model the Fixture System and the assembly process for compliant parts. Then, a robust analysis of the variations in the model with respect to the modelling factors is performed by a Design of Experiments. A case study on an automotive fender is discussed. The results demonstrate that the modelling strategy of the clamping operation have the main effects, while the modelling of locators scheme, spot joints and FEM meshing are less important.

Keywords: 3D tolerances | Compliant parts | Computer Aided Tolerancing | Design method | Robust analysis

[19] Gherardini F., Santachiara M., Leali F., Enhancing heritage fruition through 3D virtual models and augmented reality: An application to Roman artefacts, Virtual Archaeology Review, 10(21), 67-79, (2019). Abstract

Abstract: The spatial characteristics of museum exhibitions may limit visitors' experience of the artefacts on display. In the case of large artefacts, limited space may affect their whole visualization, or inhibit the visualization of the details farthest from the observer. In other cases, the storage of artefacts in distant sites (museums or archaeological areas) may influence their knowledge process or the possibility for comparative analysis. Moreover, the precarious state of preservation of some artefacts, with damaged or missing parts, makes it difficult to perceive their original appearance. To overcome these limitations, we propose an integrated approach based on 3D virtual models and Augmented Reality (AR) to enhance the fruition of artefacts, improving their visualization, analysis and personal/shared knowledge, also by overcoming space and time constraints. The final AR application is an easily accessible tool for most users from a mobile device, used both inside and outside museums, opening new perspectives for fruition. The framework encourages the use of free and open source software and standard devices, to maximize their dissemination and exploit the potential of such technologies, which is far greater than current use in the cultural heritage field. Selected case studies to test and validate the integrated framework are proposed, dealing with some Roman artefacts found in the area of Modena (Italy). The first is a Roman floor mosaic, found in Savignano sul Panaro (near Modena) in 2011, of which less than half of its original 4.5 x 6.9 m surface is preserved. The others are two Roman funerary lion sculptures: the first is one of two lions flanking the main door of Modena Cathedral, and the second, well-preserved but damaged, is housed in the Museo Lapidario Estense of Modena. Finally, the application was tested by museum experts and visitors both inside and outside the museum, and positively assessed.

Keywords: Augmented reality (AR) | Image-based reconstruction | Real-time visualization | Roman archaeological objects | Virtual modelling | Virtual museum

[20] Gherardini F., Panari D., Leali F., Identification of the main contributors in the 3D tolerances assessment in mechanical transmissions, Lecture Notes in Mechanical Engineering, 152-161, (2019). Abstract

Abstract: The management of spatial dimensional variations and 3D tolerance stacks is a key issue to achieve high performance and robust solutions. The state of the art in 3D tolerance analysis addresses two main difficulties: On the one hand, the issue about the dimensioning and tolerancing methods, and the related annotation transfer from 2D drawings to 3D parts. On the other hand, the lack of integration of design methods for 3D tolerance stacks calculation in the design process and, moreover, the restricted application fields in which tolerance methods are applied, as in aerospace or automotive fields. In this scenario, we propose a Computer-Aided Tolerancing (CAT)-based approach, integrated within the embodiment design of the product development and able to support the analysis and the design of 3D tolerance stacks in mechanical assembly, by simulating the 3D effects of both the dimensional and geometrical tolerances. Focusing on a gearbox assembly, the CAT-based approach aims to identify the main contributors (sources) of variation within the tolerance stacks, by means of a statistical and sensitivity analysis. After defining the design inputs (involved parts, tolerances definition, assembly sequence, and required measurements), we follow a bottom-up approach, starting from the part tolerances as set by the designers, up to the assembly tolerances. The CAT software simulates how the tolerances vary within their ranges. Finally, we are able to identify the main contributors to variation, which may require tightening their tolerance values, in order to improve the performance of the gearbox assembly.

Keywords: 3D tolerance analysis | Computer aided tolerancing | Design method | Gearbox assembly | Geometric dimensioning and tolerancing

[21] Gherardini F., Mascia M.T., Bettelli V., Leali F., A Co-Design Method for the Additive Manufacturing of Customised Assistive Devices for Hand Pathologies, Journal of Integrated Design and Process Science, 22(1), 21-37, (2019). Abstract

Abstract: Additive Manufacturing technologies are particularly suitable for developing highly customised products, even in rehabilitation and occupational therapy fields. Nowadays it is easy and cheap to design and produce such artefacts, although they require systematic approaches and standardized tests to validate their effectiveness. Therefore, this paper proposes a methodological approach for the application of Additive Manufacturing technologies to the co-design of assistive devices, focusing on rheumatoid or scleroderma patients. These patients present hand and finger disorders that limit simple everyday tasks, and need assistive devices to protect the damaged joints. The commercial assistive devices available on the market generally lack of customisation in dimensions and morphology, or their aspect is too stigmatizing. In order to achieve a better correspondence between patients' needs and assistive devices, we propose to involve the patients in a co-design team, in order to directly transfer their desires and creativity in unconventional solutions. The assistive devices are parametrically modelled and virtually prototyped in order to assess their functionality and customisation, and then additively manufactured. Finally, their effectiveness is tested by patients by means of standardized assessment tests that generate useful feedback. The paper proposes a case study about an assistive device for daily living activities.

Keywords: Additive Manufacturing technologies | Assistive device | Co-design | Occupational therapy | Parametric modelling | Rheumatoid arthritis

[22] Santachiara M., Gherardini F., Leali F., An Augmented Reality Application for the Visualization and the Pattern Analysis of a Roman Mosaic, IOP Conference Series: Materials Science and Engineering, 364(1), (2018). Abstract

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

[23] Gherardini F., Santachiara M., Leali F., 3D Virtual Reconstruction and Augmented Reality Visualization of Damaged Stone Sculptures, IOP Conference Series: Materials Science and Engineering, 364(1), (2018). Abstract

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

[24] Zardin B., Borghi M., Gherardini F., Zanasi N., Modelling and simulation of a hydrostatic steering system for agricultural tractors, Energies, 11(1), (2018). Abstract

Abstract: The steering system of a vehicle impacts on the vehicle performance, safety and on the driver's comfort. Moreover, in off-road vehicles using hydrostatic steering systems, the energy dissipation also becomes a critical issue. These aspects push and motivate innovation, research and analysis in the field of agricultural tractors. This paper proposes the modelling and analysis of a hydrostatic steering system for an agricultural tractor to calculate the performance of the system and determine the influence of its main design parameters. The focus here is on the driver's steering feel, which can improve the driver's behavior reducing unnecessary steering corrections during the working conditions. The hydrostatic steering system is quite complex and involves a hydraulic circuit and a mechanical mechanism to transmit the steering to the vehicle tires. The detailed lumped parameters model here proposed allows to simulate the dynamic behavior of the steering system and to both enhance the understanding of the system and to improve the design through parameters sensitivity analysis.

Keywords: Agricultural tractors | Hydrostatic steering system | Rotary valve analysis | Sensitivity analysis | Simulation

[25] Gherardini F., Leali F., Reciprocal Frames in Temporary Structures: An Aesthetical and Parametric Investigation, Nexus Network Journal, 19(3), 741-762, (2017). Abstract

Abstract: This paper deals with the use of reciprocal frames in temporary gridshell structures, such as architectural pavilions in expositions and installations. These architectural examples can benefit from the use of short, easy to handle, generally joint-free, and repeatable “modules” in order to create particular self-supporting structures. The lightweight and interwoven grid obtained by connecting short elements according to the reciprocity principle is structurally efficient and, at the same time, aesthetically pleasing, mainly due to the resulting tessellation. The paper firstly investigates the connection between efficiency and aesthetics. The last part of the paper investigates some temporary architectural pavilions from both an aesthetical and parametric point of view. In order to deepen our understanding of these structures, they are re-modelled according to a bottom-up approach by means of a constraint-based parametric CAD modeller. In this way, a reciprocal frame can be explored and modified by the parametric arrangement of its generative elements, which, like a natural organism, grows in self-generating forms.

Keywords: Aesthetics | Architectural pavilions | Natural form | Parametric modelling | Reciprocal Frame | Shell structure | Tessellation

[26] Gherardini F., Renzi C., Leali F., A systematic user-centred framework for engineering product design in small- and medium-sized enterprises (SMEs), International Journal of Advanced Manufacturing Technology, 91(5-8), 1723-1746, (2017). Abstract

Abstract: The systematic integration of user needs in the product design is a key issue in industry, especially for small- and medium-sized enterprises (SMEs), which suffer a lack of engineering methods and resources. Moreover, most of the approaches described in the literature are not flexible enough to be tailored on the SMEs’ needs, involve users only in the early design phases and are not fully accessible due to the high cost in their implementation. The present paper proposes a user-centred design methodological framework specifically focused on SMEs, which supports the designer from both design and manufacturing aspects along the engineering product design process. The framework integrates engineering methods with Web-based software tools, which enable the communication and the concurrent work of the design team, and supports direct participation of users. Beside state-of-the-art methods, the framework allows the integration of specifically tailored techniques. The framework is successfully validated through an industrial case study developed in collaboration with an Italian SME. As a result, the design of an injection-moulded housing and the related interfaces of a biomedical electronic device are achieved with a reduction of uncertainty and development time, by involving users throughout the design phases and suggesting methods and tools on the basis of the designers’ know-how and SME’s specific resources.

Keywords: Decision theory | Design methodology | Product design | QFD | SMEs | User-centred design

[27] Gherardini F., Zardin B., Leali F., A parametric CAD-based method for modelling and simulation of positive displacement machines, Journal of Mechanical Science and Technology, 30(7), 3253-3263, (2016). Abstract

Abstract: We present an efficient and user-friendly parametric CAD-based design method for the graphical description of positive displacement machines, exploiting commercial parametric CAD software and a tailored interface. An executable module simulates the motion of the machine components, analyzes the machine geometry, and automatically extrapolates the geometrical data from the 3D CAD model, generating data files that can be directly used for following fluid dynamic analyses. The graphical approach supports investigation of the machine performance and exploring optimized design variants. The method has been applied to three industrial test cases: An external gear pump, an axial piston pump, and a gerotor pump. A complete case study focused on the external gear pump is proposed, as well as the results from the other two types are summarized. We validate the CAD-based method by comparing the obtained data with the data coming from the application of state-of-the-art analytical methods.

Keywords: CAD-based method | Engineering design | Graphical approach | Positive displacement machine | Software interface

[28] Gherardini F., Leali F., A Framework for 3D Pattern Analysis and Reconstruction of Persian Architectural Elements, Nexus Network Journal, 18(1), 133-167, (2016). Abstract

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