Method Of Adaptive Fault Diagnosis And Selfhealing Control For Hypersonic Flight Vehicles

Hypersonic flight vehicles have broad military and civil application prospects,and the harsh flight environment in which they are located makes faults more likely to occur.This situation places higher requirements on the stability,safety and reliability of the flight control system.Therefore,it is of greatly practical significance to design a self-healing control scheme for the faulty system.This paper takes hypersonic flight vehicles as research objects,and considers sensor/actuator faults and external disturbances in order to study fault diagnosis and self-healing control schemes.The main research contents of this paper are shown as follows:For the cruise system of hypersonic flight vehicles with multi-sensor faults,a fault diagnosis and self-healing control scheme based on an adaptive augmented observer is proposed.In order to facilitate the modeling of multi-sensor faults,the nonlinear longitudinal dynamic model is transformed into a T-S fuzzy model.In order to detect and isolate the faults quickly and accurately,a Luenberger observer is introduced to generate output residuals,and the convergence of the observer and the amplitude of external disturbance are considered in the design of the threshold.An improved augmented observer is used to estimate multiple sensor faults simultaneously.The disturbance estimation is performed by using an adaptive law with proportional and differential parts.This method is not limited by the amplitude of the disturbance.Finally,considering faults and disturbances,an adaptive fuzzy feedback fault-tolerant controller is designed to ensure that the system output can track the given commands stably.For the cruise system of hypersonic flight vehicles with elevator fault,a fault diagnosis and self-healing control scheme based on an adaptive high-order state observer is proposed.In order to simplify the design of the observer and controller,the complex nonlinear model of the aircraft is transformed into an affine nonlinear model by feedback linearization technique,and an elevator bias fault model is then established.In order to establish a fault detection mechanism and improve the accuracy of the detection,a high-order state observer is designed for the altitude and velocity subsystems,respectively,considering the observer output and disturbances to determine a reasonable detection threshold.By introducing the disturbance rejection level and designing an adaptive high-order state observer for fault estimation,the algorithm is robust to disturbance.On this basis,a nonlinear disturbance observer is proposed for estimation.Finally,an adaptive nonlinear feedback fault-tolerant controller is designed to ensure that the flight altitude and velocity of the aircraft can track the given commands stably.For the attitude system of hypersonic flight vehicles with surface fault,a fault estimation and self-healing control scheme based on the adaptive back-stepping method is proposed.Based on the affine nonlinear model of the attitude system,a surface bias fault model is established.In order to obtain the output residual required by the detection mechanism,a nonlinear fault detection observer is designed to estimate the attitude angle,thereby determining the time when the fault occurs.In order to accurately estimate the fault and reduce the impact of external disturbances,an adaptive robust observer is designed based on the augmented system,so that the estimation error can satisfy the L₂-gain disturbance rejection level.Finally,an adaptive back-stepping fault-tolerant controller is designed to ensure that the system output can track the given commands stably.Based on the MATLAB platform,the above-mentioned fault diagnosis and self-healing control schemes are compared and simulated.The simulation results show that the proposed schemes in this paper can quickly and accurately estimate faults and effectively compensate for them,thereby ensuring the closed-loop stability and accurate tracking of the system.