Tracking control of an uncertain heavy load robot based on super twisting sliding mode control and fuzzy compensator

This paper presents a new combined strategy to control an uncertain heavy load robot with position disturbance caused by flexible foot, and the control strategy is realized only by position feedback. Firstly, deformation during motion is analyzed, and the position transformation generated by this deformation is treated as periodic position disturbance and non-periodic position disturbance. Then, a control method combined by computed torque controller (CTC), super twisting sliding mode (STSM) controller, and fuzzy compensator is designed for the robot dynamic system to track ideal trajectory. Meanwhile, a proportional-integral-derivative (PID) controller based on CTC is designed as a comparison to verify the trajectory tracking performance and robustness of the combined strategy under external disturbances. Finally, simulation results show that CTC-STSM is clearly found to converge faster and to show stronger ability to suppress interference than CTC-PID. The addition of fuzzy compensator (CTC-STSM-Fuzzy) can further reduce the sliding mode chattering effect and improve the performance.