Semi-global robust stabilization of MIMO nonlinear systems by partial state and dynamic output feedback

We study the problem of semi-global robust stabilization for a class of mul ti-input multi-output (MIMO) uncertain nonlinear systems which cannot be tr ansformed, via a change of coordinates and a state feedback, into a lower d imensional zero dynamics driven by a set of chains of integrators, but more complicated interconnected structures. The systems considered here, which distinguish from those studied early in the literature, possess a new featu re that they are non-affine in the control inputs. Sufficient conditions ar e presented for the existence of a linear high-gain partial state controlle r and/or a nonlinear dynamic output compensator, achieving robust semi-glob al asymptotic stability. Both the partial state and output dynamic controll ers are also explicitly constructed. (C) 2001 Elsevier Science Ltd. All rig hts reserved.