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

Human Arm simulation for interactive constrained environment design

During the conceptual and prototype design stage of an industrial product, it is crucial to take assembly/disassembly and maintenance operations in advance. A well-designed system should enable relatively easy access of operating manipulators in the constrained environment and reduce musculoskeletal disorder risks for those manual handling operations. Trajectory planning comes up as an important issue for those assembly and maintenance operations under a constrained environment, since it determines the accessibility and the other ergonomics issues, such as muscle effort and its related fatigue. In this paper, a customer-oriented interactive approach is proposed to partially solve ergonomic related issues encountered during the design stage under a constrained system for the operator's convenience. Based on a single objective optimization method, trajectory planning for different operators could be generated automatically. Meanwhile, a motion capture based method assists the operator to guide the trajectory planning interactively when either a local minimum is encountered within the single objective optimization or the operator prefers guiding the virtual human manually. Besides that, a physical engine is integrated into this approach to provide physically realistic simulation in real time manner, so that collision free path and related dynamic information could be computed to determine further muscle fatigue and accessibility of a product designComment: International Journal on Interactive Design and Manufacturing (IJIDeM) (2012) 1-12. arXiv admin note: substantial text overlap with arXiv:1012.432