High gain observers applied to problems in disturbance attenuation, H∞-infinity optimization and the stabilization of uncertain linear systems

In recent years, a number of approaches have been developed for solving the following problem in linear systems theory: Design a state feedback control so that the norm of a specified transfer function is less than a given bound over all frequencies. This paper deals with the case in which not all system states can be measured. It shows that if a certain minimum phase condition is satisfied then the transfer function bound achievable using state feedback can be asymptotically recovered using a high gain observer.