Stable adaptive observers and controllers

The paper deals two basic problems in systems theory-the identification and control of umknown plants-using a model reference approach. In both cases, methods for determining the adaptive laws for adjusting unknown parameters which result in an asymptotically stable overall system are considered. The first part of the paper deals extensively with the identification problem and presents important developments in this area in recent years; the second part describes briefly some of the questions associated with the control problem which is unresolved at the present time.