Ability of a Robot to Travel Through its Free Work Space in an Environment with Obstacles

International audienceThis article presents a new geometric analysis of the free work space of a robot among obstacles. The free work space (FW) is defined as the set of positions and orientations that the robot's end effector can reach, according to the joint limits and the various obstacles lying in the environment. The aim is to give global descriptions of the robot's ability to move in the operational space (which coincides with Carte-sian space when only position coordinates are specified). The main contribution of this work is the characterization of the effects of obstacles on the work space geometry, as well as on its topology. The ability of a robot to move freely in its work space (called the "moveability") is difficult to describe and needs stringent formalizations. The concept of move-ability is introduced through various properties and their corresponding necessary and sufficient conditions. Using a Constructive Solid Geometry (CSG) Computer-Aided Design (CAD) description of robots and obstacles and an octree model of the FW, these properties permit characterization of selected moveability areas in the FW, where, for instance, any n points can be linked together or where any continuous trajectory can be achieved without changing configuration. This new global description is of great interest for the user of CAD systems when designing robotic cells

Designing a Virtual Manikin Animation Framework Aimed at Virtual Prototyping

International audienceIn the industry, numerous commercial packages provide tools to introduce, and analyse human behaviour in the product's environment (for maintenance, ergonomics...), thanks to Virtual Humans. We will focus on control. Thanks to algorithms newly introduced in recent research papers, we think we can provide an implementation, which even widens, and simplifies the animation capacities of virtual manikins. In order to do so, we are going to express the industrial expectations as for Virtual Humans, without considering feasibility (not to bias the issue). The second part will show that no commercial application provides the tools that perfectly meet the needs. Thus we propose a new animation framework that better answers the problem. Our contribution is the integration - driven by need ~ of available new scientific techniques to animate Virtual Humans, in a new control scheme that better answers industrial expectations

Passive Control Architecture for Virtual Humans

International audienceIn the present paper, we introduce a new control architecture aimed at driving virtual humans in interaction with virtual environments, by motion capture. It brings decoupling of functionalities, and also of stability thanks to passivity. We show projections can break passivity, and thus must be used carefully. Our control scheme enables task space and internal control, contact, and joint limits management. Thanks to passivity, it can be easily extended. Besides, we introduce a new tool as for manikin's control, which makes it able to build passive projections, so as to guide the virtual manikin when sharp movements are needed

Integration of a Balanced Virtual Manikin in a Virtual Reality Platform aimed at Virtual Prototyping

International audienceThe work presented here is aimed at introducing a virtual human controller in a virtual prototyping framework. After a brief introduction describing the problem solved in the paper, we describe the interest as for digital humans in the context of concurrent engineering. This leads us to draw a control architecture enabling to drive virtual humans in a real-time immersed way, and to interact with the product, through motion capture. Unfortunately, we show this control scheme can lead to unfeasible movements because of the lack of balance control. Introducing such a controller is a problem that was never addressed in the context of real-time. We propose an implementation of a balance controller, that we insert into the previously described control scheme. Next section is dedicated to show the results we obtained. Finally, we propose a virtual reality platform into which the digital character controller is integrated

CONCEPTION INTEGREE (PREDIMENSIONNEMENT EN ENVIRONNEMENT IMPRECIS)

LA CONCEPTION MECANIQUE EST UN PROCESSUS COMPLEXE ET INTERACTIF. LA RECHERCHE D'UNE SOLUTION OPTIMALE DE PROBLEME MULTIOBJECTIF ET MULTIVARIABLE EST SOUVENT DIFFICILE ET DES FOIS IMPOSSIBLE A TROUVER. DE PLUS, LES PROBLEMES DE CONCEPTION SONT MULTIDISCIPLINAIRE ET REQUIERE UN GRAND NOMBRE DE VARIABLES. TROUVER UN COMPROMIS EST GENERALEMENT UNE TACHE DIFFICILE. DANS UN CONTEXTE D'INGENIERIE INTEGREE ET D'ENVIRONNEMENT IMPRECIS, NOUS PROPOSONS UNE METHODE D'AIDE A LA DECISION QUI PERMET AUX INGENIEURS D'ESTIMER LA PERTINENCE DES SOLUTIONS ENVISAGEES AU REGARD DE CHAQUE POINT DE VUE METIER. NOTRE METHODE S'AVERE PARALLELE, FLEXIBLE ET MODULAIRE. NOUS EMPLOYONS LA LOGIQUE FLOUE POUR PRENDRE EN COMPTE LES IMPRECISIONS ISSUES DU CAHIER DES CHARGES. AINSI CHAQUE SYSTEME MECANIQUE EST ASSOCIE A UN POINT DE VUE METIER. NOUS POUVONS TROUVER UN ENSEMBLE DE CANDIDATS SATISFAISANT L'ENSEMBLE DES POINTS DE VUE EN AGREGEANT LES FONCTIONS DE SATISFACTION. NOUS APPLIQUONS CETTE METHODE AU CAS DU DIMENSIONNEMENT D'UNE TRAPPE D'AVION. LES RESULTATS S'AVERENT APPRECIABLES. ENSUITE, DES RESEAUX DE NEURONES SONT EMPLOYES POUR APPRENDRE ET REPRESENTER LES FONCTIONS DE SATISFACTION DE CHAQUE POINT DE VUE METIER. IL S'AGIT D'UNE ENCAPSULATION ET D'UNE CAPITALISATION DE MACRO-POINTS DE VUE. UN DIMENSIONNEMENT D'UN REDUCTEUR EST PROPOSE COMME APPLICATION INDUSTRIELLE DE SYNTHESE.NANTES-Ecole Centrale (441092306) / SudocNANTES-BU Sciences (441092104) / SudocSudocFranceF