Global adaptive output feedback tracking for nonlinear systems linear in unmeasured states

A global adaptive output feedback dynamic compensator is proposed for stabilization and tracking of a class of systems that are globally diffeomorphic into systems in generalized output-feedback canonical form. This form includes as special cases the standard output-feedback canonical form and various other forms considered previously in the literature. Output-dependent nonlinearities are allowed to enter both additively and multiplicatively. The system is allowed to contain unknown parameters multiplying output-dependent nonlinearities. 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 asymptotic tracking. It is also shown that this assumption can be removed by introducing extra dynamics. This represents the first adaptive output-feedback tracking results for this class of systems.