Typical Fault Diagnosis Method For Actuator Of A Pressure Regulating System

The electro-hydraulic servo actuator of the intake pressure control system is an important component of the high-altitude simulation test bench(referred to as the high-altitude bench).The electro-hydraulic servo system of high altitude platform is a complex nonlinear system integrating machinery,hydraulic and electricity.The fault mechanism is relatively complex,and it is difficult to determine the location and cause of the fault.At the same time,the fault diagnosis of the electro-hydraulic servo actuator directly determines the experimental efficiency of the intake pressure control system.Therefore,designing an effective fault diagnosis method is of great significance.This thesis focuses on the degradation of the performance of the electro-hydraulic actuator,which leads to a decrease in the control quality of the intake system or poses a serious threat to the safe operation of the intake system.A joint simulation based adaptive robust sliding mode observer fault diagnosis method is studied.The main research content is as follows:(1)Construction of system execution mechanism model and analysis of typical faults.Firstly,by analyzing the structure and working principle of the jet tube servo valve,mathematical modeling of the torque motor,armature feedback rod component,and jet tube amplifier was completed.Then,further utilizing the AMESim secondary development software AMESet combined with mathematical models,the submodel design of the jet tube amplifier and armature feedback rod component was completed.The establishment and simulation analysis of the jet tube servo valve and hydraulic cylinder models were also completed in AMESim.Finally,in terms of fault analysis,the complexity of the faults was explained by analyzing the types,mechanisms,and manifestations of faults in the jet pipe servo valve and hydraulic cylinder components.Injecting typical faults into the AMESim whole valve model and reproducing faults further validated the effectiveness of the model.(2)Research on the fault diagnosis method for the electro-hydraulic servo actuator of a certain intake control system.A fault diagnosis method for electro-hydraulic servo actuators using adaptive robust sliding mode observer is proposed to address system model uncertainty and external disturbances.Firstly,a robust sliding mode observer was designed based on the mechanism model of the electro-hydraulic servo actuator.The output estimation of the observer was compared with the actual output of the system model to generate residuals,and fault diagnosis was carried out through the changes in residuals.Then,adaptive thresholds are used to reduce the false alarm rate and missed alarm rate of fault detection.Finally,a fault decision design is carried out,using a set of sliding mode observers to diagnose typical faults of the actuator.(3)Simulation verification of adaptive robust sliding mode observer fault diagnosis based on joint simulation.Firstly,a joint simulation fault diagnosis platform is established by combining the AMESim model and the MATLAB diagnostic model.Then,three typical faults of the electro-hydraulic servo system of the high-altitude platform,including stuck slide valve,hydraulic cylinder leakage,and electrical open circuit,were set up for simulation verification of the adaptive robust sliding mode observer diagnosis algorithm.Finally,the output of the sliding mode observers,including spool displacement,piston rod speed,and left chamber pressure of the hydraulic cylinder,is compared with the actual output of the actuator model to generate residuals,and fault diagnosis is completed through the changes in residuals.