Robust adaptive control for non-linear systems in generalized output-feedback canonical form

Design of global robust adaptive output-feedback dynamic compensators for stabilization and tracking of a class of systems that are globally diffeomorphic into systems in generalized output-feedback canonical form is investigated. This form includes as special cases the standard output-feedback canonical form and various other forms considered previously in the literature. Output-dependent non-linearities are allowed to enter both additively and multiplicatively. The system is allowed to contain unknown parameters multiplying output-dependent non-linearities and, also, unknown non-linearities satisfying certain bounds. Under the assumption that a constant matrix can be found to achieve a certain property, it is shown that a reduced-order observer and a backstepping controller can be designed to achieve practical stabilization of the tracking error. If this assumption is not satisfied, it is shown that the control objective can be achieved by introducing additional dynamics in the observer. Sufficient conditions under which asymptotic tracking and stabilization can be achieved are also given. This represents the first robust adaptive output-feedback tracking results for this class of systems. Copyright (C) 2003 John Wiley Sons, Ltd.