Research On Aeroengine Signal Reconstruction Method Based On Sliding Mode Observer

Currently,the aerospace engine's Full Authority Digital Electronic Control requires a large number of sensors to monitor engine status and conduct health management to ensure good performance and safe operation of the aero-engine.Some sensors need to be installed in the high temperature and high pressure inside the aero-engine,making the sensor prone to failure,directly affecting the safety and reliability of the engine control system and even the engine body.When the sensor fails,the reconstruction of aero-engine signal can make FADEC still obtain the true value of the engine parameters,which is of great significance for improving the safety and reliability of the engine.This paper takes DGEN380 engine as the research object,and uses the sliding mode observer to reconstruct the signal of the aero-engine speed sensor.The research contents are as follows:Firstly,a sliding mode observer for a general linear system was designed.In order to verify the robustness of the sliding mode observer,different types of interference are injected into the system.The simulation results show that the sliding mode observer is robust to various types of interference,and the equivalent of output error injection can better“track”the actuator fault value of the system in limited time,which lays a foundation for the subsequent reconstruction of the aero-engine signal based on the sliding mode observer.Secondly,aiming at the problem of poor robustness of traditional aero-engine signal reconstruction methods,a method of aero-engine signal reconstruction based on sliding mode observer is proposed.Firstly,the sensor failure is equivalent to the virtual actuator failure through system dimension enhancement.Secondly,the stability of the sliding mode observer is proved by Lyapunov equation,and the gain of the observer is solved by linear matrix inequality.Finally,the equivalent of output error injection is processed to achieve aero-engine signal reconstruction.The simulation results show that the designed sliding mode observer can realize the signal reconstruction of a single sensor fault of aero-engine and multiple sensor faults.The method is robust and the accuracy of reconstructed signal is better than the traditional Kalman filter.The reconstruction method has higher precision and wider application range.Thirdly,the signal reconstruction method based on sliding mode observer can better realize the aero-engine signal reconstruction and is more accurate than the Kalman filter method.However,when the output estimation error is less than zero,the reconstructed signal is always smaller than the actual value.To solve this problem,an aero-engine signal reconstruction method based on adaptive sliding mode observer is proposed.The adaptive rate is added to the gain of the general sliding mode observer,so that the system automatically adjusts the gain according to the size of e_y:when e_y is less than zero,the gain of the adaptive sliding mode observer is positive;when e_y is greater than zero,the gain is negative.The simulation results show that compared with the signal reconstruction method based on sliding mode observer,the method can improve the accuracy of aero-engine signal reconstruction,and the scope of application is broader than the former.