A robust asymptotic regulating control scheme is proposed for a class of ti
me-varying uncertain nonlinear systems with both additive nonlinear uncerta
inties and unknown multiplicative terms. The signs of these multiplicative
terms, so-called control directions, are unknown. The class of systems can
be of arbitrary dynamic order, and except for the unknown multiplicative te
rms, they satisfy the strict feedback condition. (C) 1999 Elsevier Science
Ltd. All rights reserved.