Characteristic Analysis of High Order Disturbance Observer

The disturbance observer (DOB) has been widely utilized in high-precision and high-speed motion control applications. It has been reported that a fast and precise servo system, which has low-sensitivity to disturbance and parameter variations, can be realized with a simple structure by using a high order disturbance observer. The disturbance observer uses a nominal model of the plant to create an estimate of the disturbance. This estimate is then used to compensate for the disturbance effects. In this paper, analysis of the servo system realized by disturbance observer in low-frequency region is presented. Simulation and experimental results show the effectiveness of the proposed design method.