Linearly combined suboptimal mixed H/sub 2//H/sub /spl infin// controllers

In this paper we consider the problem of minimizing the H/sub 2/ norm of a closed-loop map over all static state feedback controllers while satisfying an H/sub /spl infin// constraint on another closed-loop map. We propose a readily computable suboptimal solution to the pure mixed H/sub 2//H/sub /spl infin// problem by restricting the search to a class of linearly combined controllers. Such mixed linearly combined controllers yield smaller closed-loop H/sub 2/ norms than those obtained by using the central solutions of the H/sub /spl infin// problem. Moreover, the mixed controllers achieve the optimal H/sub 2/ performance whenever the optimal H/sub 2/ controller satisfies the H/sub /spl infin// bound.