Robust output regulation for a class of uncertain nonlinear systems

This note deals with the robust output regulation problem for a class of nonlinear systems with dynamic uncertainties. The design procedure is mainly divided into two parts. Firstly, the internal model part is proposed to extend system equations and convert the robust output regulation to robust stabilization problem. Then, the combined backstepping and small-gain approach is introduced to tackle with the corresponding unknown nonlinearities and dynamic uncertainties. It has been demonstrated that the proposed controller regulates the error signal to zero while maintaining overall signals uniform boundness.