The Study Of The Fault Diagnose System Based On The Electric Power Assisted Steering

With the flying development of the automobile industry and theelectronic technology, the two technologies integrate and change with eachpassing day, as this reason, the application of the electron in the automobileindustry has become far-ranging more and more. From the mechanicalsteering system, the hydraulic steering system, the electronic hydraulicsteering system, the automobile steering system has run to the ElectronicAided Power Steering (EPAS) utilizing the modern control and electronictechnology by now. EPAS consumedly improves the momentumperformance, the economy performance and the security of the automobile.At the same time the electronical processing of the automobile controlfetches a lot of difficulties about the diagnosis and the servicing of theautomotive fault, thereby, every big automobile company all over the worldcommence to study and design the fault diagnosis system (FDS). Thefunction of the fault diagnosis system is to watch the going of every part inthe control system using the electronic control unit (ECU). When FDS detectfaults it will display the fault information and execute relevant operation toensure the safety of the driver. The development of EPAS needs the rapidadvancement, development of the EPAS fault diagnosis technology.People put forward higher demand to the software design and thehardware design of the EPAS fault diagnosis system.Studies and designs in this paper rightly aiming at the EPAS faultdiagnosis system. Because of the status quo that the EPAS technologyprogress rapidly and the demands to the fault diagnosis technology of EPASis heightened increasingly, the paper lives up to suit the remedy to the casein the course of the study and design to the problem.Based on the analysis to the problem, preparing and referring to a massof information, The paper puts forward the collectivity design scheme thaton-line fault diagnosis and out-line fault diagnosis combine to complete thewhole design. According to the essential design scheme the essentialdesign method that software design and hardware design combine isaccordingly confirmed. The paper completes the design of the on-line faultdiagnosis system using the FPGA hardware design method and completesthe design of the out-line fault diagnosis system using the softwaremodularization design method that VC++ associates with MATLAB.The paper finishes the design of the EPAS on-line fault diagnosissystem and the EPAS on-line fault diagnosis system after a mass ofstudying, designing and emulating. The paper achieves functions of signalfiltering, signal fault diagnosis and fault code displaying in the on-line faultdiagnosis system and the out-line fault diagnosis system separately.In the material course of designing of the EPAS on-line fault diagnosissystem and out-line fault diagnosis system, the paper mainly finishes thestudy and design of matters below:(1) Data communications based on CAN bus technologyData communications between ECU and the on-line fault diagnosis boxIn the course of the hardware designing of data communicationsbetween ECU and the on-line fault diagnosis box, the paper uses the CANbus technology. 89C51 is node microprocessor. In the CAN buscommunications interface, the communications controller is SJA1000, andthe CAN bus drivers is 82C250. At the same time the paper specifies thehardware circuit diagram and the assembler of the data communications.Studying to the scheme data communications between ECU and PCBecause the data in the out-line fault diagnosis system root in the datacollection card, the paper briefly introduces the blue print of the design ofdata communications between ECU and PC. There are mostly two means toimplement data communications between ECU and PC. One is using theupper PC's serial interface and CAN bus to finish data communications. Theother means is using the upper PC's parallel interface and CAN bus to finishdata communications. The paper also briefly introduces the implement ofdata communications by the two means.(2) The design of the EPAS on-line fault diagnosis system based on FPGAIn the course of the material FPAG hardware design to the EPASon-line fault diagnosis system the paper expatiates on the process ofdesigning each functional module (including signal processing module,series to parallel transition module and signal analyzing module) in detailbased on the essential modularization design thinking, and fetches out therelevant simulation results.The paper finishes the modularization design of every functionalmodule by programming in the HDS2004 environment with Verilog languageas the rock-bottom hardware descriptive language, emulating eachfunctional module in the ModelSim SE environment and synthesizing in theSynplify environment.(3) The design of the EPAS out-line fault diagnosis systemThe paper finishes designing to the EPAS out-line fault diagnosissystem by means of software design method. In the same way, the papercompartmentalizes the whole EPAS fault diagnosis system to signalprocessing module, signal analyzing module and the code display module inthe process of the software design based on the essential modularizationdesign thinking. Each module is programmed with MATLAB language,debugged and emulated in the MATLAB environment. Ultimately the threemodules are tied in. The whole design process of the EPAS out-line faultdiagnosis system is completed.In this design process, the paper finishes data communicationsbetween MATLAB and PC's serial interface, and finishes designing signalfiltering module based on the Mallat arithmetic, the numerical value range ofthe signal detecting module and the code display module. The user interfaceof the EPAS out-line fault diagnosis system is designed in the VC++environment. The united programming between MATLAB and VC++ isimplemented in the paper.After all the studying and design, the paper finally completes the designof the EPAS fault diagnosis including the on-line fault diagnosis system andthe out-line fault diagnosis system.Here we impersonally analyze the design thinking and the methodsused in the process of the design. We can find that there are severalinnovative aspects of content in the paper.(1) In the aspect of selecting the whole design schemeThe paper puts forward and confirms the united programming betweenMATLAB and VC++ as the whole design scheme through in-depth compareand analysis to the capability and the characteristic of the on-line faultdiagnosis system and the out-line fault diagnosis system. The paperenables the amalgamation between the on-line fault diagnosis technologyand the out-line fault diagnosis technology come true. The two learn fromother's strong points to offset one's weakness in the EPAS fault diagnosissystem. The paper achieves the fault diagnosis results that on-line is realtime and out-line is precise.(2) In the aspect of selecting the method of the signal filteringThe paper filters the EPAS signal with the Mallat arithmetic in the signalprocessing module after studying and referring to plentiful information. Inthis part the paper compares the filtering effect between the filtering basedon hardware method and the filtering based on Mallat arithmetic andadequately explains the advantage of the filtering EPAS signal based on theMallat arithmetic.(3) In the aspect of FPGA hardware designThe EPAS fault diagnosis hardware design in the paper is differentfrom the usual fault diagnosis hardware designs, it designs the EPAS on-linefault diagnosis system with the FPGA hardware method, and that the usualfault diagnosis hardware designs often use the Single Chip Micyoco (SCM).The FPGA design method can make the hardware functional design morevivid, and make the restriction to the hardware resource depressedconsumedly. The FPGA application in the EPAS fault diagnosis hardwaredesign is an adventurous attempt, and it affords a brand-new and effectualdesign means for the fault diagnosis hardware design for the future.