Redundant Parallel Manipulator Research Articles

Intelligent Motion Task Planning of Redundant Parallel Manipulator.

In this study, a robot that utilizes a parallel mechanism at parts of its body is proposed.The robot combines locomotion and manipulation, and consists mainly of four units of three degree of freedom (hereafter called DOF) parallel mechanism with linear actuators and two grippers attached to both sides of its body.The robot has high redundancy with 14-DOF without grippers.The purpose of this study is to realize the"intelligent motion"in the redundant parallel manipulator that performs the basic motion of the proposed robot.The robot determines its motion while considering its redundancy and improves it using actuator information derived from the motion.First, we analyze the kinematics and statics about the parallel manipulator, and show a method to optimize the solution of inverse kinematics that includes the redundancy problem.Next, we discuss the intelligent motion task planning of the parallel manipulator using actuator information.Two methods are proposed based on the optimization of inverse kinematics.One optimizes the motion by iteration.The other optimizes the motion successively in continuous motion tasks.Finally, the effectiveness of the proposed methods is verified experimentally.

Intelligent Motion Task Planning of Redundant Parallel Manipulator.

In this study, a robot using a parallel mechanism as parts of the body is proposed. robot integrates locomotion and manipulation, and mainly consists of four 3 DOF parallel mechanism with linear actuators and two grippers attached to both sides of the body. The robot has high redundancy with 14-DOF without grippers. purpose of this study is to realize Intelligent Motion of the redundant parallel manipulator that performs basic motion of the proposed robot. robot determines the motion with considering its redundancy and improves it by using actuator informations that are taken in through the motion. First, this paper treats the analysis of kinematics and statics about the parallel manipulator, and shows the method to optimize the solution of inverse kinematics that includes redundancy problem. Next, the intelligent motion task planning of the parallel manipulator using actuator informations is mentioned. Two methods are proposed based on optimization of inverse kinematics. One optimizes the motion by iterative exercise. other optimizes the motion successively in continuous motion tasks. Finally, the effectiveness of the proposed methods were verified through the experiment.

Redundant parallel manipulators

Parallel manipulators are closed-loop mechanisms that feature high nominal load and high positioning ability. Usually, they have the same number of actuators than their degree of freedom, but in some cases, it may be interesting to have more actuators than needed, i.e., to consider redundant parallel manipulators. We will show that redundancy is interesting for solving the forward kinematics, for singularities and obstacle avoidance, for improvement in force control, and for kinematic calibration. Another aspect of redundant parallel manipulators is their use for building variable geometry trusses, i.e., highly redundant spatial structures that may be of interest for spatial applications or for applications where obstacle avoidance is critical. © 1996 John Wiley & Sons, Inc.

Kinematic Inversion of Parallel Manipulators in the Presence of Incompletely Specified Tasks

In this paper, the kinematic inversion of redundant parallel manipulators in the presence of incompletely specified tasks is formulated as an optimization problem. The performance index used is the condition number of the Jacobian matrix of the manipulator which is a measure of Jacobian invertibility. In order to optimize this index along a partially prescribed Cartesian trajectory, the concept of trajectory map is introduced. It is also shown that the optimum value of the free parameter that minimizes the condition number is not a continuous function of the prescribed Cartesian coordinates. An on-line algorithm producing continuous joint histories is then discussed. This method has been implemented and tested, as illustrated with the results presented here.