Robust Control of Nonlinear Uncertain Systems Under Generalized Matching Conditions

This paper consider the problem of stabilizing nonlinear uncertain systems. First, we define for nonlinear uncertain systems the generalized matching conditions which encompass a larger class of uncertain systems than the existing matching conditions. Then, a systematic procedure of robust control design is developed for the class of systems satisfying the generalized matching conditions. The procedure is recursive and straightforward, and makes the stability results be easily established. The proposed control is a continuous and bounded function of the system state and requires only nonlinear bounding functions on the size of uncertainties. Global stability in terms of either asymptotic, exponential, or uniform ultimate bounded stability is guaranteed under the proposed control. Extension to tracking problem is shown to be trivial.