Necessary and sufficient conditions for H-∞ static output-feedback control

Necessary and sufficient conditions are presented for static output-feedback control of linear time-invariant systems using the H-infinity approach. Simplified conditions are derived which only require the solution of two coupled matrix design equations. It is shown that the static output-feedback H-infinity solution does not generally yield a well-defined saddle point for the zero-sum differential game; conditions are given under which it does. This paper also proposes a numerically efficient solution algorithm for the coupled design equations to determine the output-feedback gain. A major contribution is that an initial stabilizing gain is not needed. An F-16 normal acceleration design example is solved to illustrate the power of the proposed approach.