Robust stabilization of MIMO nonlinear systems by backstepping

The problem of global robust stabilization is investigated for a class of m ulti-input, minimum-phase nonlinear systems with unknown time-varying param eters or disturbances belonging to a given compact set. It is assumed that the systems admit a special structure, which is much more general than stri ct feedback form. It is shown that such a structure makes it possible to co nstruct both Lyapunov functions and robust stabilizing controllers by the b ackstepping method. (C) 1999 Elsevier Science Ltd. All rights reserved.