Showing papers by "Damien Chablat published in 2005"
TL;DR: It is showed that the proposed strategies yield Pareto-optimal solutions, which differ by the kinematic performances outside the prescribed Cartesian cube (but within the workspace bounded by the actuated joint limits), which are illustrated with numerical examples for the Orthoglide prototype design.
54 citations
05 Dec 2005
TL;DR: In this article, a new control architecture is proposed for virtual humans in interaction with virtual environments by motion capture. But it cannot be used for all tasks, and thus must be used carefully.
Abstract: In 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.
21 citations
TL;DR: In this article, a necessary and sufficient condition for 3R positioning manipulators with orthogonal joint axes to have four distinct inverse kinematic solutions (IKS) was derived, and the resulting condition is explicit and states that the last link length of the manipulator must be greater than a quantity that depends on three of its remaining DH-parameters.
Abstract: Positioning 3R manipulators may have two or four inverse kinematic solutions (IKS). This paper derives a necessary and sufficient condition for 3R positioning manipulators with orthogonal joint axes to have four distinct IKS. We show that the transition between manipulators with 2 and 4 IKS is defined by the set of manipulators with a quadruple root of their inverse kinematics. The resulting condition is explicit and states that the last link length of the manipulator must be greater than a quantity that depends on three of its remaining DH-parameters. This result is of interest for the design of new manipulators.
17 citations
18 Apr 2005
TL;DR: In this paper, a spherical wrist with parallel architecture is designed for inspection of immersed piping, and the design constraints related to the application, such as the compactness of the mechanism, the symmetry of the elements in order to ensure static and dynamic balance and the possibility for the mechanism to fill the elliptic form of the ell sections.
Abstract: The design of a spherical wrist with parallel architecture is the object of this article. This study is part of a larger project, which aims to design and to build an eel robot for inspection of immersed piping. The kinematic analysis of the mechanism is presented first to characterize the singular configurations as well as the isotropic configurations. We add the design constraints related to the application, such as (i) the compactness of the mechanism, (ii) the symmetry of the elements in order to ensure static and dynamic balance and (iii) the possibility of the mechanism to fill the elliptic form of the ell sections.
15 citations
01 Nov 2005
TL;DR: In this article, the authors presented a new six degree-of-freedom haptic device using two parallel mechanisms, called orthoglide and agile eye mechanism, which are decoupled to simplify the direct and inverse kinematics.
Abstract: The aim of this paper is to present a new six degree-of-freedom (dof) haptic device using two parallel mechanisms. The first one, called orthoglide, provides the translation motions and the second one produces the rotational motions. These two motions are decoupled to simplify the direct and inverse kinematics, as it is needed for real-times control. To reduce the inertial load, the motors are fixed on the base and a transmission with two universal joints is used to transmit the rotational motions from the base to the end- effector. The main feature of the orthoglide and of the agile eye mechanism is the existence of an isotropic configuration. The length of the legs and the range limits of the orthoglide are optimized to have homogeneous performance throughout the Cartesian workspace, which has a nearly cubic workspace. These properties permit to have a high stiffness throughout the workspace and workspace limits that are easily understandable by the user.
4 citations
01 Mar 2005
TL;DR: In this paper, a family of 3R orthogonal manipulators without offset on the third body can be divided into exactly nine workspace topologies, defined by the number of points cusps and nodes that appear on these singular curves.
Abstract: RESUME. Une famille de manipulateurs a 3 articulations rotoides et a axes orthogonaux sans decalage sur le troisieme segment se divise en neuf topologies d’espace de travail differentes. Une topologie est definie par le nombre de points cusps et de nœuds qui apparaissent sur les surfaces de singularite. En se basant sur cette classification, on evalue les manipulateurs etudies selon deux indices de performances dont le premier est le conditionnement qui est relatif a l’espace articulaire tandis que le second est la proportion de la region a 4 solutions par rapport a une sphere englobant l’espace de travail a l’espace de travail. On determine la topologie d’espace de travail dans a laquelle se trouve appartiennent les manipulateurs ayant les meilleurs indices de performances. ABSTRACT. A family of 3R orthogonal manipulators without offset on the third body can be divided into exactly nine workspace topologies. The workspace is characterized in a half-cross section by the singular curves. The workspace topology is defined by the number of cusps and nodes that appear on these singular curves. Based on this classification, we evaluate theses manipulators by the condition number related to the joint space and the proportion of the region with four inverse kinematic solutions compared to a sphere containing all the workspace. This second performance number is in relation with the workspace. We determine finally le topology of workspace to which belong manipulators having the best performance number values. MOTS-CLES : manipulateur orthogonal, classification, singularite, cusp, nœud, topologie d’espace de travail, conditionnement. KEYWORDS: orthogonal manipulator, classification, singularity, cusp, node, workspace topology, condition number.