Second order sliding mode with time delay control for uncertain robot manipulators

This paper proposes a second order sliding mode combined with time delay controller to track a desired trajectory for robot manipulators with unknown dynamics and external disturbances. The motivation for using second order sliding mode (SOSM) mainly relies on its appreciable features, such as high precision and elimination of chattering in addition that it ensures robustness. However, the SOSM problem is that the unknown dynamics and the disturbances may be amplified, which makes the system unstable. Then, using the time delay allows to benefit from the robustness of the second order sliding mode while reducing its major drawback. The stability and the robustness of the proposed controller is verified by using the classical Lyapunov criterion. The proposed controller is implemented in real time on the seven-degrees-of-freedom (7-DOF) ANAT robot arm and compared with the sliding mode with time delay control (SMTDC) to prove its superiority.