Robert Iacob

Contact identification for assembly–disassembly simulation with a haptic device

Assembly/Disassembly (A/D) simulations using haptic devices are facing difficulties while simulating insertion/extraction operations, such as removing cylinders from holes. In order to address this configuration as well as others, an approach based on contact identification between components is presented in this paper. This approach can efficiently contribute either to a new A/D simulation preparation process relying on two types of shape representations (mesh and CAD NURBS models), or directly to the real time simulation process when it is performed with 6D haptic devices. The model processing pipeline is described and illustrated to show how information can be propagated and used for contact detection. Then, the contact identification process is introduced and illustrated through an example.

Implementation and evaluation of a model processing pipeline for assembly simulation

Purpose The paper aims to present the processing pipeline of an assembly immersive simulation application which can manage the interaction between the virtual scene and user using stereoscopic display and haptic devices. A new set of elements are integrated in a Collaborative Virtual Environment (CVE) and validated using an approach based on subjective and objective users’ performance criteria. The developed application is intended for Assembly/Disassembly (A/D) analysis, planning and training. Design/methodology/approach A mobility module based on contact information is used to handle the assembly components’ movements through real-time management of collision detection and kinematically constraint guidance. Information on CVE architecture, modules and application configuration process are presented. Impact of device type (3 degrees of freedom (DoFs) vs 6 DoFs) over user’s experience is evaluated. Parameters (number of assembled components and components assembly time) are measured for each user and each haptic device, and results are compared and discussed. Findings Test results proved the efficiency of using a mobility module based on predefined kinematic constraints for reducing the complexity of collision detection algorithms in real-time assembly haptic simulations. Also, experiments showed that, generally, users performed better with 3 DoFs haptic device compared to 6 DoFs haptic equipment. Originality/value The proposed immersive application automates the kinematical joints inference from 3D computer-aided design (CAD) assembly models and integrates it within a haptic-based virtual environment, for increasing the efficiency of A/D process simulations.

Virtual Reality in Orthopedic Surgeons Training

Nowadays the use of Virtual Reality (VR) based surgical simulators or training environments is becoming more and more spread in the medical world. These are usually dedicated to the development and improvement of novice trainees’ skills by helping them to learn different surgical techniques, to use proper instrumentation or to practice surgical protocols, but also in the training of expert surgeons for conserving their skills, for planning or rehearsing new, complicated or rare procedures. In this general context of interest, our paper aims at answering the following questions: What are the main requirements for a haptic device in order to be successfully used in the virtual training of orthopedic surgeons What requirements are mandatory to be included in an orthopedic surgery haptic-based training application for providing a realistic user’s experience These are legitimate questions considering that surgical education can really benefit the advantages offered by such virtual simulators only if they can satisfy a list of requirements among which high level of immersion and interactivity, realistic 3D virtual models and constraints of anatomical structures, good correspondence between real and simulated cases (i.e. a natural ‘behavior’ and ‘feeling’ of simulated anatomy). The focus of the literature review presented in this paper will be on orthopedic VR simulators for drilling, sawing and fixing implants screws, pins and plates, with an emphasize on devices’ characteristics and applications features. This study enrolls in the trend of improving user’s immersion experience at a cost as low as possible, representing the basis on which an innovative and affordable haptic device and an application for training basic orthopedic surgical skills are proposed for development in further research.

Method and Software for Analyzing the Assembly/Disassembly Operations of Mechanical Products

Enrolling in the current trends of using collaborative virtual environments and virtual reality techniques for engineering applications, the current paper presents the synthetic results of a research in which an innovative method and software application were developed for analyzing and simulating the Assembly/Disassembly (A/D) operations of mechanical products. Starting from the 3D CAD model of an assembly and using connection interface and mobility operator concepts, the application supports the designers in generating valid A/D plans by determining the interfaces between components, calculating the components mobility and identifying the functional role of components in an assembly. Thus, the developed software provides designers an automated tool for analyzing A/D operations, obtaining and simulating A/D sequences, useful in the design phase of a mechanical product, for training the operators, as well as for improving the productivity of activities such as recycling, maintenance and reusing. Moreover, the application was conceived so that, in a further step, to be integrated in an immersive environment, offering a realistic simulation in two modes of interaction: free mode and kinematically guided. Finally, in order to validate the proposed methods and concepts, the application was tested for evaluating users’ satisfaction degree.

Robotic Welding Cells Configuration

This paper deals with electric arc robotic welding, the main objective being the optimal structure configuration of the flexible Robotic Welding Cells (RWC). To this purpose, the authors propose a new algorithm for the configuration of the cell structure based on a set of optimization criteria. Thus, to determine the optimum RWC structure, the working cycle of the technological welding process and some process parameters influencing the welded ensemble are improved as well.