Enhancing the trajectory tracking performance capabilities of position-controlled manipulators

This paper addresses the problem of enhancing the performance capabilities of position-controlled robot manipulators. The proposed strategy aims at adaptively generating the position set-points for the standard position controller of the robot, so that the desired behavior is obtained even in the presence of system uncertainty. This algorithm is computationally simple, does not require knowledge of both manipulator payload model parameters and dynamics, and is implemented in decentralized form. It can be shown that this control strategy is globally stable and that the ultimate size of the controller errors can be made arbitrarily small. The performance of the proposed control scheme is illustrated through actual hardware experiments with a COMAU Smart S2 anthropomorphic manipulator. The results show that the additional controller provides a way to enhance the performance of a standard PID regulator often in use for industrial robot manipulators, while still keeping it in operation.