Fault Diagnosis And Fault-tolerant Control Of Unmanned Ducted Fan Vehicle

In this thesis,a series of methods are independently proposed to guarantee the reliability of a novel tandem ducted fan unmanned vehicle.Aiming at the minor faults,a robust fault-tolerant control based onH_?synthesis is put forward.Further,an active fault tolerant control system is constructed,combining online fault detection and isolation system with reconfigurable control allocation,to solve the problems caused by actuator faults.The main contents can be summarized as follows:1)The robust fault-tolerant control based onH_?synthesis is investigated,and such a scheme for both inner-loop and out-loop flight is designed to tolerate the minor faults of both the body and actuators.Regarding the minor faults as the uncertainty on the vehicle,structured singular value and mixed sensitivity method are utilized to synthesize a structured controller under various constraints,such as rapidity,accuracy,robustness,disturbances rejection and actuators anti-windup.Subsequently,the parameters of controller are tuned via nonsmooth optimization algorithm which provides smooth transition between flight conditions without post-processing or interpolation.Supported by the results of numerical simulations and flight tests,the scheme is verified that it can guarantee a reliable flight performance in both time and frequency domain.2)An active fault tolerant system is completely design,consisting of a n online fault detection and isolation(FDI)module and reconfigurable control allocation.In order to cover wider flight envelope,an unscented multiple model adaptive estimation method(UMMAE)is proposed for the FDI,as an extension of traditional method,aiming at monitoring the health of each actuator without any extra sensors.The simulation results demonstrated that the actuator faults can be handled with minor ambiguity,rapid response and low computational load,indicating a more efficient operation than traditional methods.3)A control allocation module with explicit laws is designed in order to handle all the potential controllable faults.Given the appropriate fault detection results,there is no need to redesign the controller when such faults occur,since the control allocator can compensate for the fault.Typical fault modes were simulated by Matlab/Simulink,the results demonstrated that the negative influence caused by actuator faults can be eliminated by designed controller rapidly and efficiently,and the flight reliability is guaranteed in severe fault modes.