A Design Method of Servo System using High Order Disturbance Observer

Optimization of Robust Stability based on Quadratically Stabilized Control

Abstract

A high order disturbance observer can realize a fast and precise servo system with simple structure, which has low-sensitivity to parameter variation and disturbance. However, the conventional design methods for the disturbance observer can hardly satisfy specifications for the robust stability and the relative stability for parameter variations. On the other hand, a quadratically stabilized control design method based on LQ design theory satisfies those specifications. The weight matrices design in LQ design theory, however, is not systematic. In this paper, we propose a simple design method for the quadratically stabilized servo system using high order disturbance observer, which satisfies the robust stability and realizes the optimal relative stability for parameter variations. We then apply this strategy to the design of a position servo system, such as a linear drive table with inertia variation, and realize the robust stability optimized servo system.