Minimal-Order Observer with a Function of Estimating Unmeasurable Inputs by High-Gain Feedback Control

Abstract

A controller with a function of estimating unmeasurable inputs based on a minimal-order observer has been proposed previously. However, it seems very difficult to synthesize the disturbance attenuation controller based on the observer, because the synthesis method of the controller gain, which can simultaneously perform disturbance attenuation and internal stability of a closed-loop system, has not been investigated. In this paper, a novel synthesis method of the controller with a minimal-order observer, which can remove mismatched disturbances (i.e., disturbances do not meet the matching condition), is investigated. The basic concept is based on two considerations: 1) the system matrix of the measurement output estimator can be arbitrarily given and 2) synthesis of the compensator gain can be formulated as a synthesis problem of the high-gain feedback control system. Consequently, systematic synthesis of a controller that can simultaneously perform disturbance attenuation and provide internal stability can be achieved.