SEMIGLOBAL STABILIZATION OF A CLASS OF NONLINEAR-SYSTEMS USING OUTPUT-FEEDBACK

We consider the stabilization of a class of multivariable nonlinear sy stems, about an equilibrium point at the origin, using output feedback . In particular, we deal with a class of systems which can be transfor med into a global normal form with no zero dynamics. By semiglobal sta bilization we mean that for every compact set of initial conditions, w e can design an output feedback controller that stabilizes the origin and includes the given compact set in the region of attraction. The sy stem equations are allowed to depend on constant unknown parameters wh ich do not change the vector relative degree of the system, and the co ntroller is robust with respect to these parameters. We do not require global Lipschitz conditions.