远程诊断和汽车维修系统概述.docx

远程诊断和汽车维修系统概述.docx

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远程诊断和汽车维修系统概述

英文资料

OverviewofRemoteDiagnosisandMaintenanceforAutomotiveSystems

1.INTRODUCTION

1.1.Currentvehiclediagnosis

AllcarsandlighttrucksbuiltandsoldintheUnitedStatesafterJanuary1,1996arerequiredtobeequippedwithOn-BoardDiagnosticsII（OBD-II）.WhiletheprimaryimpetusforOBD-IIwasdiagnosticsforemissionsystems,therangeofvehiclesub-systemsaddressedbythisstandardisquitebroad.TheOBD-IIDiagnosticTroubleCodes（DTCs）aremadeupof5digits[1].Whilethesecodesareusefultoidentifyfaultysubsystems,theyaretypicallynotsufficienttoidentifyspecificfaultycomponents.

ThetroublecodesaretypicallyaccessedthroughascantoolthatispluggedintoaspecialOBD-IIvehicleconnector.Thisconnectorislocatedinthepassengercompartmentandcanbeaccessedfromthedriver'sseat.

Hand-heldscantoolsareusuallylimitedtovehiclesfromoneormoremanufacturer.Ingeneral,Chryslerproducts,allEuropeanandmostAsianimportsusetheISO9141standardforin-vehicleOBD-IIcommunications.GMcarsandlighttrucksuseSAE

J1850VPWM（VariablePulseWidthModulation）,andFordsuseSAEJ1850PWM（PulseWidthModulation）

1.2.Problemswithcurrentvehiclediagnosis

Approaches

Fromabovedescriptionwecansee,thereareseveralproblemsinthecurrentapproachtovehiclediagnosis.

1.Thediagnosisisnotstandardizedamongvehiclemanufacturers.Thisleadstohighercostswhenvehiclesfromdifferentmanufacturersaretobediagnosedbyagivenfacility.

2.Thediagnosisrequiresdrivingtoarepairfacility.Thisisaninconveniencetothedriverandasourceofuncertaintyinschedulingvehiclediagnosisandrepair.Thedrivermaybetoldtoleavethevehicleforthedaywhentheproblemcanbesolvedinanhour.

3.Acompletediagnosismayneedspecialequipmentandtrainedtechnicianhelp.Thiscanmakethediagnosisveryexpensive.

4.TheDTCinformationistypicallynotaccurateenoughtopinpointthesourceoftheproblem.Bettervehiclediagnosticalgorithmsandstrategiescouldreducethetimeneededtodiagnoseproblems.

5.Withtheincreasedsophisticationofelectroniccontrolsystemsinvehicles,thereisaconcomitantincreaseinthedifficultyofidentifyingcomponentmalfunctions.Onesymptomofthisisthediagnosisofreplacedpartsas“notroublefound”.

1.3.Currentvehiclemaintenancestrategies

Currentvehiclemaintenancestrategiesgenerallyconsistofcorrectiveandpreventivemaintenanceapproachesoracombinationofthese.Inthecorrectivemaintenanceapproach,thevehicleismaintainedonan“as-needed”basis,i.e.afterafaulthasoccurred.Thiscanbeariskyapproachasitmay,overtime,leadtounexpectedbreakdownsandmorecostlyrepairsduetohigherlevelsofdamage.Attheotherextreme,preventivemaintenancereliesonreplacingcomponentsandfluids

basedonaconservativescheduleto“prevent”possiblefailures.Althoughpreventivemaintenanceprogramsmayincreasesystemavailability,theyleadtoincreasedcostofvehicleownershipduetothereplacementofpartsandfluidswellbeforetheendoftheirusefullife.Ingeneral,preventivemaintenanceschedulesaretypicallytimeormileage-basedstrategyanddonotaccountforactualvehicleoperatingconditionsor

subsystemhealth.Asaneverydayexample,drivershavelittleideaofhowtotradeoffthemanyfactorsinoillifeandareadmonishedbytheoil-changeindustrytochangetheiroilevery3,000miles;manyvehiclemanufacturers,however,recommendmuchlongerintervalsfor“normal”drivingconditions.Studieshaverevealedthatmosttheequipmentfailuresarenotrelatedtothenumberofhoursofoperation.Manydriversuseamixofcorrectiveandpreventativestrategies,dependingonthesubsysteminvolved.

1.4.Problemswithcurrentvehiclemaintenancepractices

Correctiveandpreventativevehiclemaintenancepracticesaresub-optimalstrategiesintermsofthecostofvehicleownershipanddriverconvenience.Neither

strategyaccountsforactualvehicledrivingconditionsorcurrentcomponent/fluidhealth.Inaddition,vehicleoperatorsoftendonotreadthemaintenanceschedulesin

theirowner’smanualor,iftheydo,havedifficultyindecidingbetweenmoderateorsevereoperatingconditions.AccordingtoaSeptember15,2003reportpublishedby

theCommissionoftheEuropeanCommunity,repairandmaintenanceaccountsfor40%ofthetotallifetimecostsofvehicleownership[5].Thus,theaffordabilityofvehiclesdependsnotonlyoninitialvehiclecostbutthecostofrepairandmaintenance.

2.SIGNIFICANCEOFREMOTEDIAGNOSIS&MAINTENANCE

Recentadvancesinremotecommunications,humanmachineinterfaces,model-baseddiagnostics,electronicsandembeddedsystemtechnologiesareleadingtoadramaticshiftinthewaythevehiclesisdiagnosedandmaintained.Theseadvancesequiptheautomobileswiththecapabilitysharein-vehiclesensoranddiagnosticinformationwithremotecomputers,enablingvehiclediagnosisandmaintenancebeperformedremotelywhilethevehicleisbeingdriven.Inaddition,vehicleparametersmcanbemonitoredwhilethevehicleisbeingdrivento

determinewhenmaintenanceisnecessary.ThesecapabilitiescoupledwithincreasedconsumerinterestarethereasonswhyvehicleRD&Misdrawingincreasingattentionintheautomotiveindustry.

2.1.RemoteDiagnosis&MaintenanceBackground

RD&Misamultidisciplinarysubjectthatembodiesmanyvehiclesubsystemsandtheirassociateddiagnosticandmaintenanceneeds,aremoteanalysiscenter,and

wirelesscommunication.Anumberofrecentpatentsandarticleshaveaddressedavarietyofapplication-specificissuesrelatedtoRD&M.Examplesincludeavehiclecommunicationsystemtoestablishatwo-waycommunicationslinkbetweenthevehicleandaremotecomputer,andanautomatedvoiceresponsesystemtoprovideamethodforremotelydiagnosingavehicle.AlsoNASAhasdevelopedaremotediagnosisservertomonitorthehealthofthespaceshuttle.

Severalcompanies,includingGM’sOnStar;NEXIQTechnologiesInc.,ATXTechnologiesInc.,Toyota,VetronixInc.,JentroAG,BMW,Volkswagen,IBW,

andDearbornGroup,eitheralreadyhaveorareactivelydevelopingRD&Mapplications.GM’sOnStarsystemhasevolvedfrombeinganoptiononCadillacstostandardequipmentonnearlyallGMvehicles.OnStarintegratescellphoneservice,roadsideassistance,emergencyservice,andsimpleremotediagnosticsbasedonDiagnosticTroubleCodes（DTCs）.GMprojectsthatOnStarsystemwillbeinstalledin4millionvehiclesby2005.Afewothercarmanufacturers,including

Toyota,VolkswagenandBMW,areworkingonsimilartelematicssystemsandarerollingoutmodelswithintegratedearly-generationremotediagnostics

technologyaswell.

2.2AdvantagesofRD&M

Asdescribedinthescenariosatthebeginningofthisreport,RD&Mshouldhavetheabilitytounobtrusivelydiagnosevehiclehealthwithouttheneedtodrivetoaspecialrepairfacility.RD&Msystemscanexamineautomotivefaultcodesand

internalsensorvaluesnomatterifthecarisrunningontheroadorparkedinthegarage,withouttheinvolvementofavehicleservicetechnician.ThesereadingscanbewirelesslytransmittedtoaremoteRD&Mserver,wherevehicleinformation,suchasrecordsofvehicleserviceandpreviousrepairarestored.ARD&Mservercanusepowerfulprocessingcapabilitytoassessvehiclehealthandremindownersifmaintenanceisrecommended.Ifaproblemisdetected,thedrivercanbewarnedofthemalfunction,cangethelpfromanadvisortoassesstheseverityofproblemandtoschedulemaintenanceorrepair.Ifneeded,advanceddiagnosticalgorithmscouldberemotelydownloadedtothevehicleforperformingcomplexdiagnostictasks,andrecoveryandrescueservicescouldbeactivatedtodealwithfaultyconditionsand,possibly,savelives.

Remotemaintenanceprogramcanaidinreducingoperatingcostsandincreasesafetyby,forexample,earlydetectionoflowtirepressure,determiningwhenanoilchangeisneeded,orwhenbrakeliningsareinneedofreplacement.Earlywarningsofproblemsmaypreventsomeon-the-roadbreakdownsand,insomecases,mayavertaccidents.RD&Mshouldgivedriverspeaceofmindbytakingmuchoftheambiguityoutofthecurrentapproachestodiagnosticsandmaintenance.VehiclemanufacturerscanalsouseRD&Masanearlywarningsystemtodetectvehiclewarrantyproblemsearlyinthemodelyear.TheauthorsbelievethatasthenumberofautomobilesequippedwithRD&Mincreases,consumerswillincreasinglyrecognizethelong-termcost-to-benefitratioofthesesystems.

2.3PotentialConsumerInterestinRD&M

AutomotivetelematicsisgrowingrapidlyandRD&Misgenerallyregardedasoneofthemostimportanttelematicsservices.AccordingtoarecentsurveybyInfoMove,aSeattleproviderofpersonalized,locationbasedapplicationsandwirelessservicesforautomobiles,73percentofconsumerswouldlikeautomakersanddealerstobeabletodiagnosecarproblemsremotely.ProjectionsbyAlliedBusinessIntelligence,anOysterBay,NY-basedresearchfirm,indicatethattelematicsproductsandservicesareexpectedtogrowfromanaggregate$2.2billionglobalmarketin2001tomorethan$12.3billionby2007.AgoodindicationofthestrengthofconsumerinterestinautomotivetelematicsservicesisthegrowthofOnStarsubscribers,andtheemulationofOnStartypeservicesbyotherOEMs.

2.4RD&MforX-By-Wiresystems

X-By-Wiresystemswereintroducedinaircraftwelloveradecadeago,firstinmilitaryandthenincommercialaircraft.Thesesystemsreplacehydraulicandmechanicalsystemswithelectronicallycontrolledsystems.Ina"true"X-By-Wiresystem,thereisnohydraulicbackuptotheelectronicsystem.X-By-Wiresystemsar