ROBUST-CONTROL OF NONLINEAR-SYSTEMS WITH INPUT UNMODELED DYNAMICS

In the rich repertoire of design methodologies for uncertain nonlinear systems, the problem of unmodeled dynamics has thus far received litt le attention, We initiate the investigation of nonlinear systems with input unmodeled dynamics, First we show that even in their simplest fo rms, they can result in dramatic shrinking of the region of attraction and in finite escape time, In this paper we introduce a dynamic nonli near damping design which guarantees global boundedness in the presenc e of input unmodeled dynamics, With this design we achieve global asym ptotic stability for strict-feedback systems and output-feedback syste ms.