Multiobjective H/sub /spl infin// problems: linear and nonlinear control

In this note, we compare the value of nonlinear and linear control for a multiobjective H/sub /spl infin// control problem with a linear time-invariant (LTI) plant. We show that if the H/sub /spl infin// performance of a nonlinear feedback controller is measured by the maximum incremental gain, the optimal achievable performance with nonlinear, time-varying control is identical to that achievable by LTI control.