Multiple Observer Based Fault Diagnosis And Isolation For Aero-engine

For aircraft,aero-engine is the heart of the whole aircraft,whether the health of its work condition directly affects the safety and reliability of the aircraft and the safety of human life and property.Aero-engine has a complex mechanical structure,and the working environment is very poor,so it is a system with a high failure incidence of failure.How to diagnose,prevent or eliminate timely and correctly the various abnormal states of aero-engine before failures occur or at the early stage of failures occur and provide guidance to the operation of the system are very important to improve the reliability,security and effectiveness of the system and minimize the loss of faults,and has important scientific significance and high social value.In this thesis,the fault diagnosis and isolation method of actuator based on the linear model and nonlinear model of aero-engine is designed,and the main work is as follows:Firstly,the nonlinear model of each component is established on the basis of the whole structure of the aero-engine.At the stable operating point of aero-engine,the nonlinear model is linearized by the reasonable linearization method,so as to get the engine linearized mathematical model of stable point.Secondly,based on the structural decomposition method of linear system,the linear model of aero-engine is transformed to the special coordinate form,and the adaptive robust observer is designed to ensure the robustness of the residual signal under the external disturbance.The structure of the traditional adaptive observer is improved,and a fault diagnosis observer is designed to speed up the fault estimation of the actuator.The adaptive robust observer is transformed to the normal coordinate system and the simulation is carried out.Thirdly,based on the multi-model method,a fault observer group is established and a reasonable fault judgment mechanism is obtained by using Lyapunov analysis method to solve the fault isolation of aero-engine.Base on the appropriate fault model set,the validity of the designed fault diagnosis and isolation method is verified by simulation.Finally,a novel adaptive observer structure is proposed for a MIMO system with two or more actuator failures,and the designed fault observer is applied to fault diagnosis and isolation for aero-engine actuators.The advantage of this approach is that the residual signal can be guaranteed to respond only to the monitored fault and not to the unmonitored fault.