H-INFINITY CONTROL SYNTHESIS VIA REDUCED-ORDER LMIS

Linear matrix inequality-based approaches for H-infinity control synth esis for systems with weighting functions possibly face numerical ill- conditioning and heavy computation. In this paper, by exploiting the p otential pole/zero cancellation (mostly modes of weighting functions) in the closed-loop system, a new formulation is presented to find a fu ll-order controller via reduced-order LMIs (linear matrix inequalities ) and fewer decision variables. As a result, both numerical conditioni ng and numerical efficiency are improved. In addition, the new formula tion is directly applicable to servomechanism problems where unstable disturbance dynamics are appended for robust regulation.