On saturated-proportional derivative feedback with adaptive gravity compensation of robot manipulators

Abstract

In this paper we propose a new adaptive controller for the global regulation of robot manipulators. This controller incorporates adaptation of the gravitational torque vector to overcome parametric uncertainties in the robot and payload such as masses and inertia. Also, instead of a linear proportional feedback, the controller has a saturated-proportional-type feedback. It has been recognized that this kind of non-linear position error feedback presents practical features such as attenuation of friction effects and avoids unacceptably high torque for large position errors. By using Lyapunov's direct method, we conclude closed loop stability and global regulation. The proposed controller has been tested on a direct drive single-link arm.