Extended H-infinity control - H-infinity control with unstable weights

This paper presents a complete solution to an extended H-infinity control p roblem for a generalized plant comprising a physical system cascaded with w eights containing poles in the closed right half-plane. Necessary and suffi cient conditions for a solution to exist are obtained which guarantee close d-loop stability of the physical system and controller as well as achieving the H-infinity norm constraint on the closed loop of the transfer function matrix of the generalized plant and controller interconnection. The set of all feasible controllers is characterized. Conditions for solvability are a minimal variation on those appearing in the standard H-infinity control p roblem. (C) 2000 Elsevier Science Ltd. All rights reserved.