An Approach to Loop Transfer Recovery using Eigenstructure Assignment

One method of model-based compensator design for linear multivariable systems consists of state-feedback design and observer design [1]. A key step in recent work in multivariable synthesis involves selecting an observer gain so the final loop-transfer function is the same a the state-feedback loop-transfer function [4], [6]. This is called Loop-Transfer Recovery (LTR). This paper shows how identification of the eigenstructure of the compensators that achieve LTR makes possible a design procedure for observer gain [15]. This procedure is based on the eigenstructure assignment of the observers. The sufficient condition for LTR and the stability of the closed-loop system is that the plant be minimum-phase. The limitation of this method might arise when the plant has multiple transmission zeros.