Robust regulation for a class of parameters uncertain nonlinear systems with minimum-phase

In this paper we consider the robust regulation problems of minimum-phase nonlinear systems with the time-varying parameter uncertainties which enter linearly. It is shown that if the undisturbed system has the minimum-phase, parameters or disturbances are in a (unknown) compact set, and the generalised triangularity condition holds, then there exists a "softer" state feedback controller with observer, motivated by Freeman and Kobotovic (1993), than backstepping design used by Marino and Tomei (1993), which regulates each uncertain system in the family.