Output regulation for nonlinear systems: an overview

The problem of controlling the output of a system so as to achieve asymptotic tracking of prescribed trajectories and/or asymptotic rejection of disturbances is one of the most fundamental problems in control theory. In linear system theory, a powerful approach to the solution of this problem is the design of a controller incorporating an internal model of all exogenous inputs. The extension of this approach to nonlinear systems has been thoroughly investigated in the past 10 years. The purpose of this paper is to review the major achievements in this area as well as to outline the major problems on which the research is presently progressing. Copyright (C) 2000 John Wiley & Sons, Ltd.