Limit sets, zero dynamics, and internal models in the problem of nonlinear output regulation

In this paper, we lay the foundations for a nonequilibrium theory of nonlinear output regulation, giving a more general (nonequilibrium) definition of the problem, deriving necessary conditions, and, using these necessary conditions, we present a set of sufficient conditions and a design methodology for the solution of the problem in question. Our analysis leads to a nonequilibrium enhancement of the internal model principle.