Semiglobal robust output regulation of minimum-phase nonlinear systems

In this paper, we address the problem of semiglobal robust output regulatio n for a general class of single-input, single-output nonlinear systems. The proposed solution does not require the assumption of input-to-state stabil ity of the zero-dynamics of the plant. The design method is based on a clas sical decomposition of the control law into a stabilizing feedback and a fe edforward control, where the latter is asymptotically reconstructed by an i nternal model. The scheme exploits the passivity properties of the internal model, and combines small-gain and high-gain feedback. Simulation results for an illustrative example are included. Copyright (C) 2000 John Wiley & S ons, Ltd.