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This paper investigates the issue of adaptive fuzzy control for a category of non-strictfeedback stochastic uncertain non-linear systems. Based on event-triggered mechanism, an adaptive fuzzy controller with a simple form is designed by combining backstepping technique with fuzzy logic system. The devised controller not only ensures the output signal tracking reference signal and all signals of the closed-loop system are bounded in probability but also reduces the communication load between controller and actuator. In addition, the feasibility of the considered event-triggered mechanism is guaranteed by eliminating Zeno behaviour. Finally, the validity of the proposed result is proved by an example. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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This article is devoted to the output feedback control of nonlinear system subject to unknown control directions, unknown Bouc-Wen hysteresis and unknown disturbances. During the control design process, the design obstacles caused by unknown control directions and Bouc-Wen hysteresis are eliminated by introducing linear state transformation and a new coordinate transformation, which avoids using the Nussbaum function with high-frequency oscillation to deal with the issue. Besides, to settle the issue caused by the unknown disturbances, a novel nonlinear disturbance observer is designed, which has the characteristics of simple structure, low coupling, and easy implementation. Especially, a compensation item is constructed to offset the redundant items generated in the backstepping design process. Simultaneously, using the neural network and backstepping technology, an output feedback controller is devised. The controller ensures that all closed-loop signals are bounded, and the system output, state observation error, and disturbance observation error converge to a small neighborhood of the origin. Finally, to illustrate the effectiveness of the proposed scheme, simulation verification is carried out based on a numerical example and a Nomoto ship model.

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