Global output feedback control with disturbance attenuation for minimum-phase nonlinear systems

This paper deals with the problem of disturbance attenuation with stability for a Glass of minimum-phase nonlinear uncertain systems by output feedbac k. In contrast to the state-feedback case, a nonlinear, not necessarily lin ear L-2, gain is employed to characterize the disturbance rejection level. A constructive output feedback design is described to achieve global asympt otic stability while the effect of the disturbance on the output is diminis hed to an arbitrary degree of accuracy. Sufficient conditions are additiona lly provided to yield a nonlinear output feedback solving the standard L-2- gain disturbance attenuation problem with internal stability. (C) 2000 Else vier Science B.V. All rights reserved.