Study on Higher Order Disturbance Observer and Robust Stability

Abstract

In earlier papers, it has been reported that a fast and precise servo system, which has a low-sensitivity for parameter variation and disturbance, can be realized with simple structure by using a high order disturbance observer. However, a clear and simple design method satisfying specifications for the robust stability, the influence of the measurement noise, and the relative stability (damping characteristics) for large parameter variation has hardly been proposed. In this paper, we clarify the class of the robust servo system realized by adjusting the order of the disturbance observer and the control parameters. We apply this strategy to the design of a second delay system, such as position servo system, and realize high performance robust servo system using high order disturbance observer.