INTERNAL FORCES ANALYSIS OF THE ACTIVE OVERCONSTRAINED PARALLEL MANIPULATORS

Yundou Xu, Jiantao Yao, and Yongsheng Zhao

Keywords

Internal forces, active over constrained PM, pseudoinverse, limb stiffness

Abstract

Internal forces of the active overconstrained parallel manipulator (PM) are defined. It is the same as that of multiple manipulators handling a common payload, which would compress or extend the moving platform under the condition that only actuation forces are exerted to the moving platform. As the pseudo-inverse solution for the active overconstrained PM includes internal forces in this situation, a method to obtain the solution of actuation forces without internal forces for the active overconstrained PM is then proposed. For this method, the actuation forces on any contact points are firstly transferred to orthogonal actuation forces with the same number, and then the equivalent orthogonal actuation forces are obtained by using pseudo-inverse solution, the actuation forces are finally derived by inversing transformation matrix mapping the actuation forces to the equivalent ones. What is more, the effect of the limb stiffness on the force analysis results is also discussed for the active overconstrained PM, and some regular features are obtained, which partly reveals internal mechanism of force analysis of such PM.

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