H∞ vs. classical methods in the design of feedback control systems

A few reasons for the continued popularity enjoyed by H _∞ theory in the control community are discussed. The mixed sensitivity H_∞ robust control design problem based upon the Glover-Doyle 2-Riccati state-space approach (Doyle, Glover, Khargonekar and Francis, 1989) is considered. Particular emphasis is placed on the choice of suitable weighting functions, design parameters selected to reflect the relative importance of different design goals, upon which often hinges the successful computation of a satisfactory H_∞ optimal controller. The Glover-Doyle algorithm was used to design a H_∞ robust controller for a single-input-single-output system