Robust Output Feedback Controller for a Serial Robotic Manipulator with Unknown Nonlinearities and External Disturbances

This paper presents a robust output feedback controller for a n-link serial robotic manipulator with un- known dynamics and external disturbances. First, the robotic manipulator’s model is formulated with unknown dynamics, including joint coupling, nonlinearities, and external distur- bances. Second, an output feedback controller is proposed by combining a backstepping controller and an extended high- gain observer to estimate the unknown dynamic and external disturbances in addition to the system states. Experiments on 4 DOF robotic manipulators verify the proposed control approach. The proposed control approach achieved the end- effector’s desired trajectory under unknown system dynamics and disturbances.