On non-central H/sub /spl infin// controllers

It is demonstrated that non-central H/sub /spl infin// controllers can have advantages over the usual central H/sub /spl infin// controller. In particular, it is shown that non-central controllers can improve the quadratic performance of the closed loop. It is further shown how to characterize non-central controllers with lower order than the central controller. The analysis is made possible by a state-space representation of the free contraction based on the bounded real Riccati equation.<>