A Relay-Based Approach for Robot Motion Control With Joint Friction and Gravity Compensation

Abstract

This paper introduces a relay-based approach to control the motion of robot joints with friction and gravity load. This approach uses relay feedback tests to estimate the disturbances including Coulomb friction, viscous friction, and the gravity load. The relay feedback tests take the robot joint angular as the feedback signal and identify the friction value and the gravity load at the same time. A control scheme is then presented including a feedforward friction compensator and a feedforward gravity compensator based on the estimated results. With the disturbances properly compensated, the proposed approach improves the tracking performance of a robotic system. Simulation and experimental results are presented to verify the effectiveness of the proposed method.