Singularity-free fixed-time adaptive event-triggered fault-tolerant control for a QUAV with user-defined tracking performance

In this paper, a singularity-free fixed-time adaptive interval type-2 fuzzy fault-tolerant control scheme with user-defined tracking performance is developed for a quadrotor unmanned aerial vehicle (QUAV) with unknown actuator failures under the command-filtered backstepping control (CFBC) framework. At first, the hyperbolic tangent function and interval type-2 fuzzy logic systems (IT2FLSs) are integrated to deal with unknown nonlinear expressions, where the potential singularity problem exposed in some existing fixed-time control schemes can be effectively prevented. Using a modified CFBC technique, the matter of “explosion of complexity” exposed in the classical recursive design procedure and the negative effects caused by filter error existing in dynamic surface control are overcome. Furthermore, the fixed time adaptive resilient controllers are designed for position subsystem and attitude subsystem, separately, where the event-triggered mechanism is incorporated into controller design to relax communication bandwidth constraints. Moreover, the rigorous analysis demonstrated that the designed control scheme can ensure that all closed-loop signals are fixed-time bounded, and the tracking errors can be regulated into a residual set satisfying a user-defined tracking performance. Ultimately, the effectiveness of the proposed control strategy is validated through the simulation results.