Variable structure control with feedforward compensator for robot manipulators subject to load uncertainties

A robust control method based on equivalent control of Variable Structure Control (VSC) with feedforward compensator for robotic manipulators subject to load uncertainties is presented. The feedforward compensator is used to improve tracking precision, and the feed-sequence compensator with the Proportional Integral (PI) regulator to the sliding-mode function is used for improving the dynamical performance of sliding mode state in VSC and attenuating the chattering phenomena in conventional sliding-mode state. The experimental results in GR-2 robot manipulators with two degrees of freedom verify the effectiveness of the presented controller.