In this article, a genetic algorithm–based proportional integral differential–type fuzzy logic controller for speed control of brushless direct current motors is presented to improve the performance of a conventional proportional integral differential controller and a fuzzy proportional integral differential controller, which consists of a genetic algorithm–based fuzzy gain tuner and a conventional proportional integral differential controller. The tuner is used to adjust the gain parameters of the conventional proportional integral differential controller by a new fuzzy logic controller. Different from the conventional fuzzy logic controller based on expert experience, the proposed fuzzy logic controller adaptively tunes the membership functions and control rules by using an improved genetic algorithm. Moreover, the genetic algorithm utilizes a novel reproduction operator combined with the fitness value and the Euclidean distance of individuals to optimize the shape of the membership functions and the contents of the rule base. The performance of the genetic algorithm–based proportional integral differential–type fuzzy logic controller is evaluated through extensive simulations under different operating conditions such as varying set speed, constant load, and varying load conditions in terms of overshoot, undershoot, settling time, recovery time, and steady-state error. The results show that the genetic algorithm–based proportional integral differential–type fuzzy logic controller has superior performance than the conventional proportional integral differential controller, gain tuned proportional integral differential controller, conventional fuzzy proportional integral differential controller, and scaling factor tuned fuzzy proportional integral differential controller.

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This paper proposes a novel prescribed performance fault tolerant control for hypersonic flight vehicle nonaffine models with actuator failures. First, the hypersonic flight vehicle longitudinal model is decomposed into two subsystems: the altitude subsystem and the velocity subsystem, which are expressed in non-affine forms to design the controller. Second, a novel performance function is used to design the backstepping controller, considering the actuator failures of the altitude subsystem. Different from previous studies, the backstepping controller designed in this paper reduces the steps and computational load. For the velocity subsystem, a prescribed performance fault-tolerant control law is also designed for the nonaffine velocity subsystem with actuator failures. The novel performance function not only guarantees the transient performance and steady-state accuracy of the system but also greatly reduces the overshoot of tracking error. Finally, the Lyapunov functional is used to prove the stability of the designed control system, and the effectiveness and superiority of the method are verified by simulation. INDEX TERMS Hypersonic flight vehicles, prescribed performance, actuator failures, nonaffine model, backstepping control.

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