Nonlinear output regulation: A unified design philosophy

Abstract

In this paper, we extend to the case of higher relative degree and uncertain high-frequency gain a recently proposed method for the solution of problems of output regulation for nonlinear systems. The method is applicable to systems with possibly unstable zero dynamics, in which case the problem at issue is addressed by rendering an appropriate auxiliary system stable, with a constrain on the gain. The dynamics of this auxiliary system only depend on the zero dynamics of the controlled plant, while the constraint on the gain only depends on some parameters of the exogenous input which have to be tracked. © 2010 Springer-Verlag Berlin Heidelberg.