6,597 research outputs found
An Algorithm for Computing Cusp Points in the Joint Space of 3-RPR Parallel Manipulators
This paper presents an algorithm for detecting and computing the cusp points
in the joint space of 3-RPR planar parallel manipulators. In manipulator
kinematics, cusp points are special points, which appear on the singular curves
of the manipulators. The nonsingular change of assembly mode of 3-RPR parallel
manipulators was shown to be associated with the existence of cusp points. At
each of these points, three direct kinematic solutions coincide. In the
literature, a condition for the existence of three coincident direct kinematic
solutions was established, but has never been exploited, because the algebra
involved was too complicated to be solved. The algorithm presented in this
paper solves this equation and detects all the cusp points in the joint space
of these manipulators
A novel design for a hybrid space manipulator
Described are the structural design, kinematics, and characteristics of a robot manipulator for space applications and use as an articulate and powerful space shuttle manipulator. Hybrid manipulators are parallel-serial connection robots that give rise to a multitude of highly precise robot manipulators. These manipulators are modular and can be extended by additional modules over large distances. Every module has a hemispherical work space and collective modules give rise to highly dexterous symmetrical work space. Some basic designs and kinematic structures of these robot manipulators are discussed, the associated direct and inverse kinematics formulations are presented, and solutions to the inverse kinematic problem are obtained explicitly and elaborated upon. These robot manipulators are shown to have a strength-to-weight ratio that is many times larger than the value that is currently available with industrial or research manipulators. This is due to the fact that these hybrid manipulators are stress-compensated and have an ultralight weight, yet, they are extremely stiff due to the fact that force distribution in their structure is mostly axial. Actuation is prismatic and can be provided by ball screws for maximum precision
The Isoconditioning Loci of Planar Three-DOF Parallel Manipulators
The subject of this paper is a special class of parallel manipulators. First,
we analyze a family of three-degree-of-freedom manipulators. Two Jacobian
matrices appear in the kinematic relations between the joint-rate and the
Cartesian-velocity vectors, which are called the "inverse kinematics" and the
"direct kinematics" matrices. The singular configurations of these matrices are
studied. The isotropic configurations are then studied based on the
characteristic length of this manipulator. The isoconditioning loci of all
Jacobian matrices are computed to define a global performance index to compare
the different working modes
Séparation des Solutions aux Modèles Géométriques Direct et Inverse pour les Manipulateurs Pleinement Parallèles
International audienceThis article provides a formalism making it possible to manage the solutions of the direct and inverse kinematic models of the fully parallel manipulators. We introduce the concept of working modes to separate the solutions from the opposite geometrical model. Then, we define, for each working mode, the aspects of these manipulators. To separate the solutions from the direct kinematics model, we introduce the concept of characteristic surfaces. Then, we define the uniqueness domains, as being the greatest domains of the workspace in which there is unicity of solutions. The principal applications of this work are the design, the trajectory planning
Kinematics and Workspace Analysis of a Three-Axis Parallel Manipulator: the Orthoglide
The paper addresses kinematic and geometrical aspects of the Orthoglide, a
three-DOF parallel mechanism. This machine consists of three fixed linear
joints, which are mounted orthogonally, three identical legs and a mobile
platform, which moves in the Cartesian x-y-z space with fixed orientation. New
solutions to solve inverse/direct kinematics are proposed and we perform a
detailed workspace and singularity analysis, taking into account specific joint
limit constraints
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