C. Rizzi | Università degli Studi di Bergamo (University of Bergamo) (original) (raw)

Papers by C. Rizzi

In this paper we propose a computer-assisted methodology to improve prosthesis development proces... more In this paper we propose a computer-assisted methodology to improve prosthesis development process. We consider the case of the socket (interface between the residual limb and the mechanical part of the prosthesis) both for transfemoral or trans-tibial amputee since it requires a high level of customisation. The new paradigm forecasts the integration of the following techniques: reverse engineering and medical imaging for the acquisition of patient's morphology and bonymuscular structure, virtual prototyping to model the limb and the socket, physics-based simulation to reproduce the real movement of the patient and the interaction between the socket and stump and, finally, rapid prototyping tools for the physical realization of the product. The paper describes problems related to the implementation of each step within a real socket development process; in particular, first results regarding the reconstruction of the stump virtual model and physics-based simulation will be presented and discussed.

A CAD-oriented system is proposed for the design of complex-shaped functional cloth, provided wit... more A CAD-oriented system is proposed for the design of complex-shaped functional cloth, provided with a physics-based modelling core for simulation and virtual prototyping tasks. Textiles are physically modelled as particle grids in 3D space subjected to Newtonian dynamics, with internal spring, bending and shear forces derived from KES-F data measuring material behaviour. Interactions with the environment are expressed as external forces, collisions against obstacles, self-collisions and constraints. Differently from physics-based animation systems, the proposed system is conceived for real design purposes, and includes functionalities emulating the construction process of actual clothing and structural textiles, e.g., mesh sewing/assembly, insertion of small components, multi-layered fabric composition, mechanical shape deformation, and 2D-to-3D mapping methods. As applications, several cases of textile configurations are considered, with geometric models directly provided by industr...

Computer-Aided Design and Applications, 2016

Today's CAD modelers are very efficient in processing 3D shapes of CAD models by means of B-Rep m... more Today's CAD modelers are very efficient in processing 3D shapes of CAD models by means of B-Rep modeling operators such as pad, pocket, shaft, groove, hole, fillet and so on. At a lower description level, those modeling operators are based on Euler operators acting directly on the faces, edges and vertices of the B-Rep models. Using such a top-down approach, the designers do not have to work on low-level geometric entities, but rather manipulate so-called structural and detail features to shape directly the CAD models. However, there is still a gap between the shapes the designers have in mind and the way they have to decompose them in a succession of modeling steps. This paper proposes a new declarative modeling approach to design industrial shapes allowing the designers to interact with a CAD software at a more conceptual level. The designers enter a high-level description of the expected shapes that is then transformed through scripts into traditional CAD operators successively called to create the shapes. Compared to the traditional feature-based approaches, our declarative modeling approach is closer to the way designers think. It saves time while keeping all the advantages of existing efficient CAD modelers. This new approach aims at quickly creating drafts rather than final shapes. Those drafts can then be modified using classical CAD software in which our new approach is fully embedded. This approach is a first step towards a declarative CAD modeler.

Lecture Notes in Computer Science, 2013

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

Computer-Aided Design and Applications, 2013

This paper presents an environment, named Virtual Testing Lab-VTL, where the orthopedic technicia... more This paper presents an environment, named Virtual Testing Lab-VTL, where the orthopedic technicians can test the prosthesis replicating the traditional procedures. It is part of an innovative design framework centered on digital models of the whole patient or of his/her anatomical districts, which constitute the backbone of the whole prosthesis design process. The virtual lab permits to realize a complete amputee's digital model, an avatar, by which it is possible to execute prosthesis set up and evaluate its functionality simulating postures and movements. First, we describe the state of art of techniques used, i.e., virtual humans and motion capture systems. Then, the application of virtual humans for the prosthesis design and simulation is presented as well as preliminary results.

Computer-Aided Design and Applications, 2014

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

Methods and Tools for Co-operative and Integrated Design, 2004

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Computer-Aided Design and Applications, 2010

A novel approach to determine the undercut free parting direction of a given mold part, in B-rep ... more A novel approach to determine the undercut free parting direction of a given mold part, in B-rep format, by using the accessibility of each of its surface is presented. The proposed system is designed to classify planar, ruled and freeform part surfaces based upon the criteria of their accessibility relative to the specified directions. The orientation of each surface with respect to the considered direction is used as an input for the accessibility analysis module. To analyze the accessibility, the surfaces are swept in the different directions, based on their orientation, to form solid bodies. A number of regularized Boolean operations are performed on the swept bodies. Then, volume and geometry-based constraints are applied to classify the part surfaces based on the accessibility. Using the results of accessibility analysis in a given set of directions, feasible mold parting directions are determined. The method has been successfully implemented and tested on benchmark parts.

The design of custom-fit products, especially those with a tight interface with the human body, c... more The design of custom-fit products, especially those with a tight interface with the human body, cannot be carried out using methods and tools developed for other industrial fields (i.e. mechanical field), for mass production or for modular products, but it is necessary to realize "ad hoc" methodologies, because of the wide variety of morphologic and anatomical situations to deal with. The work presented in this paper refers to the implementation of a design paradigm for a specific custom-fit product, a prosthesis socket (interface between the residual limb and the mechanical part of the prosthesis), through the integration of advanced ICT tools coming from the reverse engineering, the physics-based modelling and simulation, and the rapid prototyping fields. The paper describes problems related to the implementation of each step within a real socket development process.

We present an innovative computer-aided procedure and the IT tools developed to design and valida... more We present an innovative computer-aided procedure and the IT tools developed to design and validate lower limb prosthesis. It uses knowledge acquired from orthopaedic technicians and represented in a KBE tool, and integrates other ICT tools, such as rev.eng., 3D modelling, CAE and virtual humans.

Volume 2: Biomedical and Biotechnology Engineering, 2010

This paper presents a new design framework to configure lower limb prostheses, both transfemoral ... more This paper presents a new design framework to configure lower limb prostheses, both transfemoral and transtibial, where the key elements are the patient digital avatar and the domain knowledge. The technician is supported during the design process by the knowledge acquired from analysis of the traditional process and represented in the framework. The last one integrates virtual prototyping tools and knowledge management techniques. A specific software tool, named Socket Modelling Assistant, has been developed to design the socket, the custom-fit component of the prosthesis. A commercial CAD system is used to model the standard components (e.g., knee, foot and tubes) and to create the final assembly. Patient avatar and his/her data (e.g., anthropometric and physiological parameters) are the backbone of the whole product design process. They guide both the selection of standard components and the modelling of the socket digital model.

ASME 2011 World Conference on Innovative Virtual Reality, 2011

ABSTRACT This paper concerns the usage of virtual humans to validate lower limb prosthesis design... more ABSTRACT This paper concerns the usage of virtual humans to validate lower limb prosthesis design. In particular, we are developing an innovative design framework centered on digital models of the whole patient or of his/her anatomical districts, which constitute the backbone of the design process. The framework integrates a set of virtual “assistants” to guide the technicians during each design task providing specific knowledge and design rules. In this paper, we focus the attention on the last step of the prosthesis deign process, i.e., the final set-up with the patient using a biomechanical model of the amputee. First, we describe the state of art on virtual humans and main features of the new design framework. Then, the application of virtual humans for the prosthesis set-up is presented as well as preliminary results.