Nonlinear robust H/sub /spl infin// control

Provides a sufficient condition for the existence of robustly asymptotically stabilizing control via state feedback and output feedback, based on nonlinear H/sub /spl infin//-control theory. It is shown that the internal asymptotic stability of the closed loop system can be achieved without the observability condition. It is also shown that positive semidefinite solutions to the Hamilton-Jacobi inequalities can be used in the construction of robustly stabilizing control. To achieve these results, the paper requires some additional conditions that an auxiliary system is internally stable and has finite induced L/sub 2/-gain.