Global output-feedback control of systems with dynamic nonlinear input uncertainties through singular perturbation-based dynamic scaling

A general class of uncertain nonlinear systems with dynamic input nonlinearities is considered. The system structure includes a core nominal subsystem of triangular structure with additive uncertain nonlinear functions, coupled uncertain nonlinear appended dynamics, and uncertain nonlinear input unmodeled dynamics. The control design is based on dual controller/observer dynamic high-gain scaling with an additional dynamic scaling based on a singular perturbation-like redesign to address the non-affine and uncertain nature of the input appearance in the system dynamics. The proposed approach yields a constructive global robust adaptive output-feedback control design that is robust to the dynamic input uncertainties and to uncertain nonlinear functions allowed throughout the system structure.