A robust high-speed position control scheme based on computed torque method for 2 DOF flexible link robot arms

Abstract

Our group has proposed a high-speed tip position control scheme (Sawada and Itamiya, 2012b) which can be applied to both a flexible link robot arm and a rigid link robot arm. It can be regarded as a natural extension of the computed torque method for a rigid link robot arm. This method can achieve a high-speed position control for 2 DOF flexible link robot arm when the exact model of the controlled object is known. However, this method does not have robustness to modelling errors. In this paper, we propose an adaptive identification method in order to decrease the modelling error from the control system in which a nominal control law is used. Then, we use the closed loop adaptive identification, considering the movable range of the robot arm. As a result, the high-speed position control can be achieved by using parameter estimates. Its validity of the proposed scheme is shown by a stability analysis and is also illustrated by the experimental results on the frequency response of the link angle and that of the deflection angle.