MIXED L-INFINITY H-INFINITY SUBOPTIMAL CONTROLLERS FOR SISO CONTINUOUS-TIME SYSTEMS/

A successful controller design paradigm must take into account both mo del uncertainty and performance specifications. Model uncertainty can be addressed using the H-infinity robust control framework, This frame work, however, cannot accommodate the realistic case where, in additio n to robustness considerations, the system is subject to time-domain p erformance specifications. In this paper we present a design procedure for suboptimal L(infinity)/H-infinity, controllers, These controllers allow for minimizing the maximum amplitude of the time response due t o a specified input, while, at the same time, addressing model uncerta inty through bounds on the H-infinity norm of a relevant transfer func tion. The main result of the paper shows that suboptimal rational cont rollers can be obtained by solving a finite dimensional convex constra ined optimization problem and a standard unconstrained H-infinity, pro blem.