Robust control of robot manipulators in the task space using the observer and voltage control strategy

In this paper, an observer-based robust control scheme is presented for robotic systems in the presence of unknown structure of nonlinearities. An adaptive observer is proposed to estimate the system state variables using the Fourier series expansion. The control law is designed using voltage control strategy (VCS). In VCS, on the contrary of torque control strategy (TCS), actuator dynamics have not been excluded. In other words, instead of the applied torques to the robot joints, motor voltages are computed by the control law. Using Lyapunov stability theorem, it is guaranteed that the controller tracking error and also the observer estimation error converge to zero. The case study is a SCARA robot manipulator driven by permanent magnet DC motors. Simulation results reveal the effectiveness of the proposed method