Sliding Mode Variable Structure Control of a Redundantly Actuated Parallel Robot

Abstract

Redundant actuation has good performance in eliminating singularities and optimizing force distribution, a 2-DOF redundantly actuated parallel robot is taken as the object of study. The dynamic model of the parallel robot is derived. Because the parallel robot is an uncertain nonlinear system, the sliding mode variable structure controller is designed considering its fast response and robustness. Then the stability of the proposed controller is analyzed. The saturation function is used instead of the sign function to eliminate the chattering of the sliding mode control. The simulation results show that the torque of each servo motor changes smoothly when using the quasi-sliding mode control. So the damage of the servo motors and robot arms is decreased. The results of the trajectory tracking demonstrate the effectiveness of the quasi-sliding mode control.