Performance Comparison of Position Controlled Robotic Stage When Force- and Position-Based Disturbance Observers are Implemented

Position control of the robotic stage when position-based and force-based disturbance observers (DOB) are implemented and their performances compared is presented in this paper. Implementation of the DOBs is aimed at improving the quality of force control by suppressing the disturbances within and into the robot mechanical system. This is because the accuracy of position control is of paramount importance since bad position control affects the reproducibility of the position perturbation which in-turn affects the production of reliable force readings for balance assessment function with the robotic stage. The overall control and disturbance suppression performance is analyzed and compared for all the control strategies. Simulations and experiments are conducted to evaluate the position control strategies. Moreover, the obtained reaction force recorded when the DOB-based position control strategies are utilized is also analyzed to point out their differences which are caused by the designed controllers.