Reduced order H2 and Hinfinity compensation via gradient techniques

H₂ and H_infinity compensation techniques required compensators of order equal to that of the plant, which may be quite large when appended with dynamic weightings. Of practical interest is how close it is feasible to get to the full order solutions with reduced order controllers. The authors introduce a technique for solving the reduced order H₂ and H_infinity problems using gradient information. First, the problem is set up in a Lagrange formulation with the necessary assumptions made. The stationary conditions are derived. Next, algorithms are presented for solving the reduced order H₂ and H_infinity problems. Finally, some examples are given to highlight the features of this method.