Robust H∞ Control of an Uncertain System via a Strict Bounded Real Output Feedback Controller

The paper presents a new approach to the robust H^∞ control of an uncertain system via an output feedback controller which is both stable and has a H^∞ norm strictly less than a specified value. The uncertain systems under consideration contain structured uncertainty described by integral quadratic constraints. The controller is designed to achieve absolute stabilization with a specified level of disturbance attenuation. The main result involves solving a state feedback version of the problem by solving an algebraic Riccati equation dependent on a set of scaling parameters. Then two further algebraic Riccati equations are solved which depend on a further set of scaling parameters. The required controller is constructed from the Riccati solutions