Research On Fault Diagnosis Of Actuator Of Vehicle Electronically Controlled Air Suspension System

With the continuous development of technology and market,electronically controlled air suspension(ECAS)systems have been widely used in passenger cars and commercial vehicles in the past decade.The electronically controlled air suspension used compressed air to act as a spring,and the spring stiffness and vehicle height could be adjusted in real time according to the actual driving conditions of the car.Due to the complex and changeable road conditions and the harsh working environment,the actuator(solenoid valve)in the electronically controlled air suspension system was prone to failure.When the actuator failed,the air suspension system could not obtain a satisfactory control effect.Therefore,it was necessary to diagnose the actuator fault of the electronically controlled air suspension system,and deal with the fault in time when the fault occured,so as to ensure the driving performance requirements of the vehicle.This topic focused on the fault diagnosis and fault-tolerant control problems of electronically controlled air suspension system actuators.The main content of this article included:(1)Briefly introduced the structure and working principle of the electronically controlled air suspension system,and summarized the research status and development trend of air suspension vehicle height adjustment,attitude control,fault diagnosis and fault-tolerant control at home and abroad.(2)Electronically controlled air suspension system modeling and actuator failure analysis.According to the theory of vehicle dynamics and air thermodynamics,a mathematical model of electronically controlled air suspension system vehicle height adjustment was established;the failure mode and cause of the actuator(solenoid valve)were analyzed,and the mathematical model of actuator failure was established.(3)Electronically controlled air suspension system for vehicle height adjustment and attitude control.In order to solve the "overcharge" and "overdischarge" problems caused by the nonlinearity and hysteresis of the electronically controlled air suspension height adjustment system,a PID/PWM controller was designed to realize the vehicle height adjustment,in order to improve the influence of road excitation and vehicle height adjustment on body posture,a fuzzy controller was designed to control the body attitude,and the vehicle height adjustment and attitude control simulation verification was carried out in the MATLAB/Simulink environment.The results showed that the vehicle height adjustment and attitude control performance were effectively improved.(4)Fault diagnosis of the actuator of the electronically controlled air suspension system.Aiming at the actuator failure of the electronic control air suspension system,the extended Kalman method was used to estimate the system state,and the residual error between the state estimation value and the measured value of the sensor was used as the fault detection index to design the fault detection and isolation method;the analysis of the electronic control air suspension system was System status under different faults,using the corresponding geometric relationship under the fault to design fault detection and isolation indicators for fault diagnosis.Different faults were set,and the two fault detection and isolation methods were simulated and verified respectively.The results showed that both methods can achieve actuator fault detection and isolation.(5)The actuator fault-tolerant control of the electronically controlled air suspension system.Use the results of fault diagnosis to estimate the fault value,determine the type of fault,and design different fault-tolerant control strategies for different faults.Take measures to stop the height control to prevent the body’s attitude from instability in response to the jam failure;use the method of online adjustment of the controller parameters for the constant gain failure,so that the system could achieve the control effect as soon as possible.Different faults were set,and the actuator fault-tolerant control strategy of the electronically controlled air suspension system was simulated and verified.The results showed that the fault-tolerant control strategy improved the vehicle height adjustment and body attitude performance.