A robust position controller synthesis for compliant mechanical systems via Disturbance Observer in state space

Abstract

This paper proposes a robust position controller for compliant mechanical systems by combining a state feedback controller and Disturbance Observer (DOb) in state space. The vibration of a compliant mechanical system is simply suppressed by placing all poles of the closed loop system on the real axis via a state feedback controller. The robustness of the controller is improved by feeding back the estimations of disturbances and their successive time derivatives so that not only matched but also mismatched disturbances are eliminated. The robust state and control input references are generated by using the Brunovsky canonical form of the controllable system and the estimations of disturbances and their successive time derivatives. It is shown that the link of a compliant mechanical system can precisely follow its reference trajectory by suppressing the vibration and disturbances when the proposed robust controller is implemented. The validity of the proposal is verified by giving simulation results of a two-mass-spring-damper system.