Robustness issues for kinematically redundant manipulator control

Kinematic redundancy of robotic manipulators has been known to be useful in accomplishing additional performance on top of the main task of tracking desired end effector trajectories. Robustness has been a major concern in manipulator control where exact physical properties of manipulators are unobtainable. In this paper, we review a method of analyzing robustness of joint space controllers for manipulators, and extend the analysis to end effector space control for the first time. We then generalize the approach to the case of kinematically redundant manipulators by introducing the redundancy as part of the manipulator states, and show that kinematic redundancy is useful in making manipulator controllers more robust. The final result of this paper is an optimization problem whose solution determines the self-motion which optimizes the system robustness