Redesign of backstepping for robustness against unmodelled dynamics

We present a redesign method to robustify backstepping control laws against linear unmodelled dynamics at the input of the plant. The admissible unmodelled dynamics are relative degree zero and minimum phase. We prove that the redesign ensures global boundedness and convergence of the closed-loop solutions to an arbitrarily small compact set around the origin. Copyright (C) 2001 John Wiley & Sons, Ltd.