A framework for nonlinear output regulation for time-varying uncertain systems

Recently, the global robust output regulation problem for nonlinear time-varying systems is considered under the assumption that the exosystem is exactly known. This paper further considers the the case where the time-varying exosystem is unknown. Conditions are given under which the problem can be converted into an adaptive stabilization problem of an augmented time-varying nonlinear system. The problem is solved for a class of time-varying output feedback systems with a time-varying uncertain exosystem.