Eigenstructure Conditions for Loop Transfer Recovery

Conditions for loop transfer recovery based on eigenstructure assignment are derived. These conditions imply constraints on the eigenvalues and certain parameter vectors of the controller. Three cases emerge - depending on the geometric stucture of the plant. For all cases explicit design rules are derived. The eigenstructure-LTR approach provides - beyond insight into mechanisms of LTR - improved flexibility in selecting the controller gains and faster recovery convergence as compared with the LQG-based LTR method. These issues are illustrated in an example.