A stable motion control system for manipulators via fuzzy self-tuning

In this paper we present a motion control scheme based on a gain scheduling fuzzy self-tuning structure for robot manipulators. We demonstrate, by taking into account the fall non-linear and multivariable nature of the robot dynamics, that the overall closed-loop system is uniformly asymptotically stable. Besides the theoretical result, the proposed control scheme shows two practical characteristics. First, the actuators torque capabilities can be taken into account to avoid torque saturation, and second, undesirable effects due to Coulomb friction in the robot joints can be attenuated. Experimental results on a two degrees-of-freedom direct-drive arm show the usefulness of the proposed control approach. (C) 2001 Elsevier Science B.V. All rights reserved.