Recursive scaling design for robust global nonlinear stabilization via output feedback

This paper proposes a novel approach to robust backstepping for global stab ilization of uncertain nonlinear systems via output feedback. The design pr ocedure developed in this paper is based on the concept of state-dependent scaling, which handles output-feedback stabilization problems of strict-fee dback systems with various structures of uncertainties in a unified way. Th e proposed method is suitable for numerical computation. The theory of the method employs the Schur complements formula instead of Young's inequality and completing the squares. This paper shows a condition of allowable uncer tainty size under which an uncertain system is globally stabilized by outpu t feedback. A class of systems is shown to be always globally stabilizable for arbitrarily large nonlinear size of uncertainties. A recursive procedur e of robust observer design for such a class of uncertain systems is presen ted. Copyright (C) 2000 John Wiley & Sons, Ltd.