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国际自动化与计算杂志 2011
Adaptive fuzzy backstepping output feedback control of nonlinear time-delay systems with unknown high-frequency gain sign
Keywords: Nonlinear systems,adaptive fuzzy control,time-delay,high-frequency gain sign,backstepping, K-filters" target="_blank">K-filters')"> K-filters&searchField=keyword">K-filters&prev_q=K-filters')"> K-filters" target="_blank">K-filters')"> K-filters,stability Abstract: In this paper, an adaptive fuzzy robust feedback control approach is proposed for a class of single-input and single-output (SISO) strict-feedback nonlinear systems with unknown nonlinear functions, time delays, unknown high-frequency gain sign, and without the measurements of the states. In the backstepping recursive design, fuzzy logic systems are employed to approximate the unknown smooth nonlinear functions, K-filters is designed to estimate the unmeasured states, and Nussbaum gain functions are introduced to solve the problem of unknown sign of high-frequency gain. By combining adaptive fuzzy control theory and adaptive backstepping design, a stable adaptive fuzzy output feedback control scheme is developed. It has been proven that the proposed adaptive fuzzy robust control approach can guarantee that all the signals of the closed-loop system are uniformly ultimately bounded and the tracking error can converge to a small neighborhood of the origin by appropriately choosing design parameters. Simulation results have shown the effectiveness of the proposed method.
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