Design of an adaptive tracker for n-link rigid robotic manipulators based on super-twisting global nonlinear sliding mode control

This paper develops an adaptive super-twisting global nonlinear sliding mode control technique for n-link rigid robotic manipulators. A novel control law is designed to guarantee elimination of the reaching phase and existence of the sliding mode around the surface right from the initial time. Furthermore, the adaptive tuning law eliminates requirement of the knowledge about the upper bounds of external disturbances. By using the proposed method, a robust controller is designed so that the tracking error of rigid manipulator is convergent to the global nonlinear sliding surface in a finite time, and strong robustness with respect to large uncertainties and disturbances is guaranteed. Illustrative simulations on a two-link elbow robot manipulator and a three degree of freedom rigid manipulator are presented to show the robustness and effectiveness of the suggested design compared to other method. Moreover, a simulation as well as experimental study of a rotary inverted pendulum system demonstrates the applicability of the proposed method.