Study On Model Based Fault Diagnosis For Electric Power Steering System

Accompanying the high speed development of vehicle industry,the importance of automobile steering system has been increasing day by day.This system is closely related to the safety,comfort and handling stability of the vehicle.In the situation that people pursue the energy conservation,environmental protection and efficiency more intensely,electric assisted power steering system has become more and more popular,probably substitute the traditional hydraulic power steering system.At the same time,as the safety and reliability of the electric assisted power steering system has become more and more perfect,the theory of fault diagnosis and separation attracts great deal of attention.The primary object of this technology is to report an emergency and identify the property of the signal when a fault occurs.In the traditional decision,the most general method is to use the difference between observer output and measuring value to form the residual signal,then judge the existence of the fault and the location of the signal.In recent years,the theory of fault reconstruction has replaced the traditional method step by step.This theory can effectively deal with the fault signal and provide the proper estimation.This paper study the method of fault diagnosis based on the EPS system,the main content is that:Firstly,this paper combine the dynamic characteristic of the EPS system and the related scheme,build the model of the system.In the next step this paper uses the Pacejka magic formula to construct the tire model and analysis the property of the four wheel vehicle model,so the comprehensive simulation system can be achieved and the common faults of the EPS system are stated.Then this paper introduce the sliding observer to diagnosis and reconstruct the fault signal.During the whole process of the fault reconstruction,the sliding motion will exist all the time,which is different from the methods in the past.Besides that,this paper use a new method to obtain the observer gain to minimize the L2 gain between the uncertainty and the fault signal to suppress the influence of disturbance.Subsequently this paper deal with the output of the system by filtering processing and extend the application of this theory to the reconstruction of the sensor.In the end,the paper states the designing method of fault simulation bedstand.We choose MB96600 single chip as the core of MCU circuit,and then complete the hardware design of fault simulation controllers,such as the fault simulation circuit,etc.Realize the HMI of simulator and implement the PC operation software by CANoe.