H-INFINITY OPTIMIZATION OF THE RECOVERY MATRIX

The emphasis of this paper is on an alternative ap roach to the Loop T ransfer Recovery (LTR) design problem based on an H(infinity) optimiza tion of a certain matrix, the Recovery Matrix. The proposed H(infinity )/LTR method handles both minimum phase systems as well as non-minimum phase systems in a common framework. In both cases, the H(infinity)/L TR design problem is transformed into an almost disturbance decoupling problem. The resulting controllers are all of the same dynamic order as the plant. As an application, robust control-objectives are studied , and sufficient conditions for the robust H(infinity) problem are giv en in a form supported by the design method presented in this paper. F urthermore, necessary and sufficient conditions for solvability of the asymptotic recovery problem is given.