Fault Detection Of Aircraft Engine Sensor Based On Sliding Mode Observers

Sensor failure is a major failure in an aeroengine control system and can lead to serious consequences.And airworthiness Regulation 33.28（d）has clear safety requirements for faults in aeroengine control systems.Fault detection techniques can identify faults in the sensor and help improve the safety of the aero engine control system.Therefore,based on the sliding mode observer,the aeroengine sensor fault detection research which takes the DGEN380 aeroengine as the object is carried out.And the main tasks are as follows:Firstly,aiming at the problem of performance index evaluation in aero-engine sensor fault detection,a fault detection evaluation method is proposed based on Monte Carlo idea,and the residual fault detection problem based on sliding mode observer is studied which is compared with the classic Kalman filter fault detection.The simulation results show that the proposed method is effective,and the fault detection based on sliding mode observer has better effect than the fault detection method based on Kalman filter.Secondly,aiming at the shortcomings that it is difficult to detect the slow change fault of the residual fault detection method based on sliding mode observer,a fault detection method based on adaptive sliding mode observer is proposed.On the basis of the common adaptive sliding mode observer,the adaptive parameters are improved.So that the observer does not appear to be out of the sliding mode surface due to the observer gain being too smal,thus ensuring the correctness of the fault detection.However,this method does not consider the influence of model uncertainty on fault detection.Therefore,based on the adaptive sliding mode observer,the matrix gain method based on L₂ gain is used to change the observer gain matrix.The robust fault detection based on sliding mode observer is studied.The simulation results show that the fault detection method based on adaptive sliding mode observer is more effective in reducing the false alarm situation than the residual fault detection method based on sliding mode observer.And the fault detection method based on sliding mode observer can meet the requirements within certain limits,and can solve the multisensor fault detection problem,while the robust fault detection based on sliding mode observer can meet the requirements in a larger range,it can only study single sensor faults due to the limitation of the selected mathemat ic a l model.Thirdly,aiming at the problem of missed detection and false detection in the general sliding mode observer used in aero-engine nonlinear mode,the problem of fault detection for aero-engine nonlinear model based on high-order terminal sliding mode observer is studied.The model is dimension-reduced by two linear transformations.The high-order terminal sliding mode observer is designed according to the dimensionality reduction model to obtain the fault reconstruction signal,and the fault detection decision-making system determines the fault occurrence.The simulation results show that the high-order terminal sliding mode observer for nonlinear systems can perform effectively in fault detection,and the fault detection performance index can meet the requirements within certain limits.