Adaptive fault tolerant compensation control for unmanned autonomous helicopter with multi-constrained conditions

In this work, the robust anti-saturation fault-tolerant control (FTC) problem is investigated for the unmanned autonomous helicopter (UAH) with multi-constrained conditions. The 6-degree-of-freedom nonlinear dynamic model of the UAH system is established. For dealing with the input saturation constraint, the auxiliary system is constructed based on the actuator saturation error. Meanwhile, the time-varying barrier Lyapunov function (TVBLF) is introduced to handle the negative effects derived from the full-state constraints. Especially, the long-standing singularity issue existing in the traditional barrier Lyapunov function, whose denominator may become zero at some point resulting in the controller divergence, is resolved by the presented TVBLF technique. Finally, combined with the adaptive compensation method, an anti-windup FTC scheme is proposed for the UAH system such that the constrained flight states are not violated and all error signals are bounded convergent. Therewith, the effectiveness of the developed method is verified via simulation results.