Georges Dumont

Bio: Georges Dumont is an academic researcher from University of Rennes. The author has contributed to research in topics: Haptic technology & Inverse dynamics. The author has an hindex of 18, co-authored 106 publications receiving 1050 citations. Previous affiliations of Georges Dumont include Centre national de la recherche scientifique & École Normale Supérieure.

Designing and evaluating a workstation in real and virtual environment: toward virtual reality based ergonomic design sessions

Abstract: This paper adresses the issue of properly designing a digital mock-up (DMU) to be used in an experiment comparing simulated assembly tasks in both real and virtual environments. Motivations and specifications relative to the experiment are reported, and the design process of the DMU is described and illustrated. Recommendations are proposed with a particular focus on specificities relative to the use of a DMU as a support for both manufacturing and virtual reality—3D visualisation and interaction. A subjective evaluation of Real (RE), Virtual (VE), and Virtual with Force Feedback (VEF) environments is provided. Results indicate a real sensory and difficulty gap between RE and VEF, whereas a smaller difference was observed between RE and VE. In further improvements of scale-1 (where the objects in VE have the same size as in the real environment), co-localized simulation using haptic devices are warranted to fill in this gap. Results also highlight the impact of cognition and sensory feedback on user’s feeling and presence sensation. Applications of such numerical designs are presented in the last section, especially focusing on collaborative design sessions. Virtual Reality based evaluation of newly designed workstations will be a way in the future to improve design and user learning processes.

Interactive simulation of CAD models assemblies using virtual constraint guidance A new method to assist haptic assembly tasks

Abstract: In the context of virtual reality (VR) and of computed aided design (CAD), haptic simulations are used to perform assembly tasks between 3D objects To ensure the good assembly of those objects, we propose a new method of interactive assembly that uses both kinematic constraints and guiding virtual fixtures Modelling a haptic assembly task as a combination of mechanical joints, we focus on the guidance of objects and on the activation cues of kinematic constraints in physical simulation In this article, we first outline the difficulties related to the haptic-assembly of CAD objects in VR simulation Introducing the virtual constraint guidance (VCG), we present a new method for haptic guidance that decomposes a task in two independent steps: a guiding step which use geometries as virtual fixtures to position objects, and a functional step which use kinematic constraints to perform the assembly task We finally present a complete application of our method on a peg-in-hole insertion task

Assessing the Ability of a VR-Based Assembly Task Simulation to Evaluate PhysicalRisk Factors

Abstract: Nowadays the process of workstation design tends to include assessment steps in a virtual environment (VE) to evaluate the ergonomic features. These approaches are cost-effective and convenient since working directly on the digital mock-up in a VE is preferable to constructing a real physical mock-up in a real environment (RE). This study aimed at understanding the ability of a VR-based assembly tasks simulator to evaluate physical risk factors in ergonomics. Sixteen subjects performed simplified assembly tasks in RE and VE. Motion of the upper body and five muscle electromyographic activities were recorded to compute normalized and averaged objective indicators of discomfort, that is, rapid upper limb assessment score, averaged muscle activations, and total task time. Rated perceived exertion (RPE) and a questionnaire were used as subjective indicators of discomfort. The timing regime and complexity of the assembly tasks were investigated as within-subject factors. The results revealed significant differences between measured indicators in RE and VE. While objective measures indicated lower activity and exposure in VE, the subjects experienced more discomfort than in RE. Fairly good correlation levels were found between RE and VE for six of the objective indicators. This study clearly demonstrates that ergonomic studies of assembly tasks using VR are still challenging. Indeed, objective and subjective measurements of discomfort that are usually used in ergonomics to minimize the risks of work-related musculoskeletal disorders development exhibit opposite trends in RE and VE. Nevertheless, the high level of correlation found during this study indicates that the VR-based simulator can be used for such assessments.

Real-Time Simulation of Brittle Fracture Using Modal Analysis

Abstract: We present a novel physically based approach for simulating realistic brittle fracture of impacting bodies in real time. Our method is mainly composed of two novel parts: 1) a fracture initiation method based on modal analysis, and 2) a fast energy-based fracture propagation algorithm. We propose a way to compute the contact durations and the contact forces between stiff bodies to simulate the damped deformation wave that is responsible for fracture initiation. As a consequence, our method naturally takes into account the damping properties of the bodies as well as the contact properties to simulate the fracture. To obtain a complete fracture pipeline, we present an efficient way to generate the fragments and their geometric surfaces. These surfaces are sampled on the edges of the physical mesh, to visually represent the actual fracture surface computed. As shown in our results, the computation time performances and realism of our method are well suited for physically based interactive applications.

An Active Tubular Polyarticulated Micro-System for Flexible Endoscope

Abstract: This paper describes an original active steering device for endoscopes and boroscopes. Its mechanical structure is based on a tubular hyper-redundant mechanism. Distributed SMA actuators with their own local controller are integrated in this structure for producing bending forces in reaction to the interaction detected between the instrument and its environment.

Principles of Neural Science

Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Biomechanics And Motor Control Of Human Movement

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A reflectance model for computer graphics

Abstract: This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic.

Robotic surgery system including position sensors using fiber bragg gratings

Abstract: A surgical instrument is provided, including: at least one articulatable arm having a distal end, a proximal end, and at least one joint region disposed between the distal and proximal ends; an optical fiber bend sensor provided in the at least one joint region of the at least one articulatable arm; a detection system coupled to the optical fiber bend sensor, said detection system comprising a light source and a light detector for detecting light reflected by or transmitted through the optical fiber bend sensor to determine a position of at least one joint region of the at least one articulatable arm based on the detected light reflected by or transmitted through the optical fiber bend sensor; and a control system comprising a servo controller for effectuating movement of the arm.

Robotically guided catheter

Abstract: Apparatus is provided for use with a steerable catheter that includes a thumb control adapted to control a deflection of a distal tip of the catheter. The apparatus includes a robot, including an end-effector, adapted to be coupled to the thumb control, and a controller, adapted to drive the end-effector to deflect the distal tip by manipulating the thumb control.