A sliding mode control of robot manipulator with variable payload

A sliding mode control based on motor angular speed control has been presented for a robot manipulator grasping a payload with mass variation. In order to guarantee the continuity of the control signals applied to the actuators of the robot manipulator, a sliding mode control with integral compensation is adopted. Improvement of robustness of the control system against payload mass variation is obtained by introducing a sliding mode feedforward signal. The control scheme is applied to a three joint robot manipulator, control performance both with payload torque compensation and without payload torque compensation are investigated. Simulation results show that the control scheme presented, is robust against payload mass variation and has satisfactory control performance.