Recent advances in output regulation of nonlinear systems

This paper presents some of our recent results in output regulation theory for nonlinear systems. We show how some of the difficulties inherent to the problem of nonlinear output regulation have been tackled and solved. In particular, we have proposed a methodology for internal model design, based on passivity theory, which enables to enlarge the class of nonlinear systems for which semiglobal robust regulation is possible. The same technique is also instrumental in solving the global output regulation problem for a restricted class of nonlinear systems. Furthermore, endowing the internal model with an adaptation mechanism, we give a solution to the longstanding problem of output regulation in presence of parametric uncertainties in the model of the exosystem. An interesting application of the proposed methodology to the design of an autopilot for a VTOL aircraft is introduced and briefly discussed.