PRACTICAL STABILIZATION OF A CLASS OF NONLINEAR-SYSTEMS WITH PARTIALLY KNOWN UNCERTAINTIES

In this paper we deal with robust control of a class of nonlinear syst ems which contain uncertainties. It can be viewed as an extension of t he work in Corless and Leitmann [IEEE Trans. Autom. Control, AC-26, 11 39-1144 (1981)] for the cases where the vector of uncertainties is onl y partially known. To cope with the uncertainties, an adaptive control ler using a dead-zone and a hysteresis function is proposed, and both the uniform boundedness of all the closed-loop signals and uniform ult imate boundedness of the system state are guaranteed. In contrast with some previous attempts to relax the a priori knowledge on the uncerta inties bounds by using a discontinuous control law, we propose continu ous control laws in this paper. Hence, chattering problems (which have practical importance) can be avoided.