Controllers that minimize a closed-loop entropy criterion provide a me
ans of trading off the robustness of H-x control with the performance
of H-2 optimal controllers. A complete solution to the problem of find
ing a controller which minimizes the entropy of the closed-loop input-
output operator for discrete-time time-varying systems is given. The a
pproach is based on a series of simpler problems. A separation princip
le is also provided. (C) 1997 Elsevier Science Ltd.