Advantages and dynamics of parallel manipulators with redundant actuation

Abstract

Parallel manipulators with redundant actuation present both problems and advantages. We analyze some major advantages of redundancy to demonstrate its usefulness. The dynamics of closed-chain mechanisms has been studied by many researchers. However, they often only consider the case of normal actuation. Few methods are suitable for closed-chain mechanisms with redundant actuation. In the article, the dynamic model of redundantly actuated closed-chain mechanisms is presented explicitly by applying Lagrange-D'Alembert formulations. As an illustrative example, the dynamic model of a 2-DOF planar parallel redundant manipulator is presented. A PID control algorithm in the joint space is experimentally implemented on this parallel manipulator to perform trajectory tracking. The experimental results show the validity of PID control.