Design Method of Robust Stable Two-Degrees-of-Freedom Control System Based on Disturbance Observer and Coprime Factorization.

Abstract

In order to get a high performance and a high accuracy for servo system in several industrial applications, a servo motor system requires a realization of robust control for wide speed range. The conventional robust control system based on disturbance observer can easily design a reference response and a disturbance rejection response, but it often does not consider a robust stable condition. In order to overcome this problem, this paper proposes a new two-degrees-of-freedom control system based on disturbance observer and coprime factorization. The proposed two-degrees-of-freedom control system considers a robust stable condition and a disturbance rejection response systematically. If the frequency band of disturbance rejection is narrow, the proposed system satisfies the robust stability conditionIn this paper, the robust speed servo system of DC servo motor is constructed by the proposed two-degrees-of-freedom control system. The experimental results show that the proposed speed servo system well regulates a motor speed robustly for wide speed range, in comparison with the conventional robust speed servo systems.