Adaptive quantized control for nonlinear uncertain systems

A direct adaptive control framework for nonlinear uncertain systems with input quantizers is developed. The proposed framework is Lyapunov-based and guarantees global ultimate boundedness (practical stability) of the closed-loop system. Specifically, the input quantizers are logarithmic and characterized by sector-bound conditions with the conic sector adjusted at each time instant by the adaptive controller in conjunction with the system response. Furthermore, for practical reasons we assume that the input logarithmic quantizers have deadzone around zero control input and we consider quantizer switching. Finally, a numerical example is provided to demonstrate the efficacy of the proposed approach. (C) 2009 Elsevier B.V. All rights reserved.