Robust Adaptive Control of Uncertain Input-Perturbed Systems via a Singular Perturbation Redesign through Dynamic High-Gain Scaling

P. Krishnamurthy and F. Khorrami (USA)


Adaptive control, robustness, high gain, dynamic scaling, singular perturbation, uncertainty.


A general class of uncertain nonlinear systems with both state and input delays is considered. The considered sys tem structure includes a core nominal system of triangular structure along with uncertain appended dynamics driven by the entire state of the system. The control input is al lowed to enter nonaffinely into the system dynamics as well as to have uncertainties coupled with it. Both state and in put delays are allowed to be time-varying and uncertain. The control design is based on our dual controller/observer dynamic high-gain scaling approach with an additional dynamic scaling based on a singular-perturbation-like re design to address the nonaffine and uncertain nature of the input appearance into the system dynamics. The pro posed approach yields a delay-independent robust adaptive output-feedback control design. The control implementa tion does not require knowledge of the time delays or any magnitude bounds thereof; the only information about the time delays that is required is a bound on the rate of varia tion of time delays.

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