Barbara Motyl

Analysis of existing methods for 3D modelling of femurs starting from two orthogonal images and development of a script for a commercial software package

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

Compensation of geometrical errors of CAM/CNC machined parts by means of 3D workpiece model adaptation

In modern industry conditions, it is very important to develop methodologies for reducing costs and achieving the maximum quality of machined parts, especially considering the dimensional accuracy of workpieces. Geometrical and dimensional inaccuracies are due to several factors, such as workpiece and tool deformation during machining, thermal distortions, tool wear, and machine tool inaccuracy. There are two main approaches used to improve the accuracy of workpieces: mapping the tool-workpiece displacement and altering the finishing tool path or the interpolated tool position to compensate the dimensional errors. The aim of this paper is to propose a new compensation approach, based on adaptation of the geometrical 3D CAD model used to generate trajectories by CAM software. The concept is to produce a first workpiece using a CAM-generated tool path. Then, the workpiece is measured using optical methods and the displacements between the ideal workpiece model and the measured point-cloud are calculated. Eventually, the displacement vectors are applied to calculate a compensated workpiece model. Such model is then used as a reference by CAM software to calculate the compensated tool path, which is applied for production of subsequent workpieces. The mathematical background and implementation details are given together with an example of application to a benchmark workpiece purposely machined with inaccurate tools. As the results show, the new approach was able to compensate the geometrical inaccuracies of the benchmark workpiece.

Comparing parametric solid modelling/reconfiguration, global shape modelling and free-form deformation for the generation of 3D digital models of femurs from X-ray images

At present, computer assisted surgery systems help orthopaedic surgeons both plan and perform surgical procedures. To enable these systems to function, it is crucial to have at ones disposal 3D models of anatomical structures, surgical tools and prostheses (if required). This paper analyses and compares three methods for generating 3D digital models of anatomical structures starting from X-ray images: parametric solid modelling/reconfiguration, global shape modelling and free-form deformation. Seven experiences involving the generation of a femur model were conducted by software developers and different skilled users. These experiences are described in detail and compared at different stages and from different points of view.

Validating CSCW strategies and applications for rapid product development in the investment casting process

The aim of this study is to apply and validate a general-purpose working methodology, derived from the analysis of processes which come from two different domains (the field of medicine and the preservation of cultural heritage), in the investment casting process. CSCW methods and tools have proven to be the best ‘gluing tool’ to bond the different activities, and thus heavily exploited during the customization of the general-purpose working methodology. This paper describes a case study performed in an industrial sector and related to the investment casting application field. It was chosen to test methodology and to demonstrate its wide applicability. The case study involved the realization of a centrifugal pump impeller, where the application of this CSCW-based methodology has delivered important results such as the reduction of product development time and the drastic reduction of production costs.

Best practices in teaching technical drawing: experiences of collaboration in three Italian Universities

This work present some best practice cases in teaching technical drawing done by three Italian Universities: Brescia, Udine, and Cassino and Southern Lazio. The intention to innovate and improve the basic technical drawing courses offered by these three Universities started in 2014. The objective of this collaboration was the development of some tools to help the students in understanding the fundamental concepts of technical drawing. The first tool developed, in order of time, was the Technical Drawing Evaluation Grid – TDEG. Starting from this tool, other learning aids were developed for the undergraduate engineering students. Some of them are: an online test for students’ self-assessment of technical drawing knowledge; a questionnaire to collect students’ opinions on different technical drawing and engineering design topics; a method for the improvement of students’ motivation to study; and a self-learning tool for teaching manufacturing dimensioning. The preliminary results of these different practices are presented and discussed in the following, posing the basis of the definition of some best practice methods that can be used for the improvement of the teaching and learning of technical drawing basic concepts for engineering students.

Additive Manufacturing Techniques for the Reconstruction of 3D Fetal Faces

This paper deals with additive manufacturing techniques for the creation of 3D fetal face models starting from routine 3D ultrasound data. In particular, two distinct themes are addressed. First, a method for processing and building 3D models based on the use of medical image processing techniques is proposed. Second, the preliminary results of a questionnaire distributed to future parents consider the use of these reconstructions both from an emotional and an affective point of view. In particular, the study focuses on the enhancement of the perception of maternity or paternity and the improvement in the relationship between parents and physicians in case of fetal malformations, in particular facial or cleft lip diseases.

Gölem project: Concept and design of a trekking/hiking wheelchair

This work concerns the growing interest in accessible tourism and describes the early stages of development of Gölem project. In particular, it takes into account accompanying activities of disabled people in mountain areas. Although literature and market analysis highlight the presence of different technical solutions used for the movement of disabled persons on rough terrains, there are only a couple of solutions based on the help of guides: Joëlette© and TrailRider©. Even if the use of these devices is generally satisfactory, our analysis has highlighted the presence of some limitations such as the difficulty of maintaining the lateral balance of the devices (which involves a considerable physical effort for the guides) and their reduced comfort for the passenger. This article describes the activities developed within the Gölem project. Its main goals are to design and to test an improved model of trekking/hiking wheelchair taking into account passengers comfort and better functionality of the device. At this moment, the design and modeling phases with the definition of dynamic parameters and of the suspension system of the device have been completed. The prototype implementation phase is in progress. Future activities will provide validation and field testing of the new solution with users.

Survey on Virtual Prototyping Technologies for Orthopedic Implants and Prosthesis Design

Nowadays, Virtual Prototyping (VP) methods are widely used for product design and development purposes. In particular, VP methods are now used also for the orthopedic products development process, to better understand the functional performance of prostheses or implants within the musculoskeletal system. In fact, developing validated virtual models of joints or of other anatomical structures may reduce design and prototyping costs and compress development cycles. The purpose of this paper is to point out first the state of art of both the VP technologies and the kinds of virtual models used in the medical field, with particular attention to those used for the design and development of orthopedic products. Then, it focuses on a qualitative analysis of some biomechanical simulation software packages (LifeMOD, AnyBody, and OpenSim) as tools for the improvement of the product design and development processes.© 2011 ASME

Reverse Engineering of a Turbine Blade: Comparison Between two Different Acquisition Techniques

Reverse Engineering is a rapidly evolving discipline. Nowadays shape acquisition systems have reached enough capabilities to reproduce complex free form objects. This paper presents a comparison between two different acquisition systems to evaluate their performances and their easy to use capabilities and to evaluate quality and accuracy of the 3D reconstructed models. To achieve this task, a complex free form object, a steam turbine blade, was acquired. After shape acquisition and data elaboration of this particular object an evaluation of the two systems characteristics and of the 3D CAD reconstructed models were done and results are illustrated here.