A zero-dynamics re-design approach to problems of nonlinear output regulation

In this paper we deal with the problem of output regulation for possibly non-minimum-phase nonlinear systems. The main goal is to provide a unifying framework for a number of recently proposed results. The underlying idea is to use a design paradigm based on zero-dynamics re-design which reduces the problem to a problem of set stabilization using high-gain feedback. In this unified setting, we are also able to show that uncertainties on the value of the so-called "high-frequency gain" coefficient of the system can be effectively handled by means of periodically varying controllers. This extends, to a nonlinear setting, robust zero-assignment techniques known for linear systems as "vibrational feedback". Copyright © 2010 Watam Press.