This paper investigates the output constraint problem for switched uncertain nonlinear systems with unknown dead-zone input. The system output is constrained by a time-varying bound, and the time-varying Barrier Lyapunov Function (BLF) is employed to guarantee that the constraint condition is not violated. The parameter of considered dead-zone is unknown but bounded. In order to remove the effectiveness caused by dead-zone, an adaptive scheme is used to adjust the bound of the unknown

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... In addition, the unknown system dynamic is taken into account, which is modeled by using fuzzy logic systems (FLSs). Combing the backstepping technique, an adaptive controller is constructed such that all the signals in the closed-loop system are bounded under arbitrary switching signal, and the system out can track the reference signal as soon as possible. Moreover, the constraint condition for system output is ensured. Finally, an example is employed to explain the effectiveness of the proposed method. INDEX TERMS Dead-zone, fuzzy logic systems, switched systems, time-varying barrier Lyapunov function. 110928 This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see http://creativecommons.org/licenses/by/4.0/ VOLUME 7, 2019