A dynamic control redesign procedure for uncertain nonlinear systems subjected to input unmodeled dynamics

A global dynamic scaling based control redesign procedure is proposed for a general class of uncertain nonlinear systems with both static and dynamic input uncertainties (input unmodeled dynamics). It is shown that if a nominal control law is available that can globally asymptotically stabilize the nominal system (without the input unmodeled dynamics), then a dynamic redesign of the nominal control law can be performed to achieve global asymptotic stabilization of the system with the uncertain input unmodeled dynamics. The proposed control redesign approach is based on adding a singular-perturbation-like dynamic system extension to the nominal control law to address the control input uncertainties. The proposed technique is applicable to a general class of nonlinear systems including both triangular and non-triangular system structures and provides a global robust output-feedback stabilizing controller.