DesignofFaultDiagnosisMonitorSystemfortheLocomotiveBearingsBasedonDSPTechnologyAbstractTherollingbearingisoneofthekeypartsofthelocomotiverunningcomponents,becauseitconditionisdirectlyrelatedtotheperformanceandsafetyoflocomotive.Inthispaper,themonitorsystemforthelocomotivebearingsbasedonDSPTMS320LF2407Aisdesigned.Thissystemdiagnosestherollingbearingfaultusingvibrationanalysismethod.ItisbasedoncomprehensiveresonancedemodulationandfastFouriertransformtechnique,anditadoptsrelatedmethodstohandletheresultoftheFFT.Iteffectivelyimprovestheresponsecharacteristics,sensitivity,differentiateandmeasurementaccuracyofthebearingfailuremonitorsystem,anditcanfulfillthemonitorandpredictionofthetransientfaultinthecourseofthelocomotiverunning.Keywords:resonancedemodulationtechnology；digitalsignalprocessor；relatedmethodsI.IntroductionThehighersafetyisrequiredtothetrainsbecauseitsspeedisraisedconstantly.Bearingfaultisoneofthemajorfactorscausingeventfultrafficaccidentsandaffectingrailsafety.Currentlytherailwaysystemusuallyusesthebearingtemperaturedetectortomonitorthelocomotivebearingcondition.Theoreticalanalysisandalotofpracticeshowthatthebearingtemperaturedetectorcanpreventaccidentsfromoccurringtosomeextent,butmostofthebearingfaultisnotsensitivetotemperature.Whenthetemperatureofthebearingisbeyondtherangeandthesystemgivesanalarm,theworsedamageofthebearinghasoccurred,andeventheincidenthadhappened.Therefore,tofindthefaultmoreearlyandaccurately,themoreadvancedmonitoringmeansmustbeadopted.Mostofthebearingfaultisverysensitivetovibrationsignal.Thefaultcancausevibrationofthebearingincreased.Comparedwithmonitoringthetemperatureofbearing,theanalysisandprocessingresultstothevibrationsignalhasmoreadvantagethanthetemperaturemeans.II.SystemcomposingandworkprocessBasedontheneed,themonitorofthebearingfaultmonitoringsystemtothelocomotivebearingsetstwodetections:itinerationdetectionsandfixeddetections.Theitinerationdetectionisusedinthenormalconditions,andthefixeddetectionisusedforthecontinuousmonitoringofthefaultbearing.Thesystemadoptsspecialcompositesensortocollectthevibrationofthebearingandthetemperaturesignalatthesametime.Afterthedataprocessing,thecorrespondingfaultlevelsandriseintemperaturearegot.Thedataacquisitionunitisdesignedinthissystem.Alarminformationwillbetransmittedtoallcarriagesthroughinterfacessothatthestaffcanhandledintime,andthesametime,thefaultdataandtherelatedinformationofthetrainsuchasthecurrentlocationandspeedwillbetransmittedtothedispatchcenterthroughGPS,whichisconvenienttoadoptcorrespondingmeasures.ThesystemblockdiagramisinFig.1.III.ThekeytechnologyofthedesignforthemonitoringsystemA.ThespectrumanalysismeansfordiagnosingbearingfaultUndernormalcircumstances,allpartsoftherollingbearing(innercircle,outercircle,roller,holdingframe)willretainthestablerelativemovementstate.Ifthesurfaceofsomeelement(exceptforholdingframe)hascrack,andthiscrackisinthesurfaceoftherollingadjacentcomponent,theinstantaneousvibrationimpulsemustbeproduced.AssumedthatthenumberoftherollerinthebearingisZ；thediameteroftherollerisd；theaveragediameterofthebearinginnercircleandthebearingoutercircle(thediameteroftherollerrevolutionpath)isD；thefrequencyofthebearingrotationisf0.Assumedthattheinnercircleisfixedandtheoutercircleiscircumvolved,thevibrationfrequencybroughtbythesurfacedefectsDispatchCenterGSMsystemIndustrycomputerInstrumentfordataInstrumentforfaultdiagnosisInstrumentforfaultdiagnosisInstrumentforfaultdiagnosisFig.1Systemblockdiagramofdifferentbearingcomponentscanbederived.Thesefrequenciescanbecalledthefaultcharacteristicsfrequencyoftheinnercircle,outercircleandtheroller.circle)(inner2101fDdZfcircle)(outer2101fDdZf(roller)1021fDddDfB.ResonancedemodulationtechnologyWecancollectvibrationsignalusingtheresonanceofthebearingcomponents,anddetecttheenvelopeofthefaultsignalusingenvelopdetector,whichcanfulfilltheanalysistothefaultcharacter.Thisiscalled“resonancedemodulationtechnology”.Thecomponentsurfacessuchastheinnercircle,theoutercircleandtherolleroftherollingbearingareeasilydamagedinlocalplaceinthecourseofoperation(suchaspittingandpeelingoff,cracking,scratchingetc.).Ifthesurfaceofsomebearingcomponentshavelocaldamageandtherollingobjectpressesthefaultdotinthecourseofcarriedoperation,itmustbringimpact.Buttheimpactlastsashorttime,andthefrequencyrangeoftheenergydivergenceiswide,sotheenergywithinthescopeofvibrationfrequencyissmall.Duetothewidebandwidthoftheimpulse,itiscertainlythatitincludeshighfrequencyintrinsicvibrationinspiringbyintrinsicfrequencyoftheinnercircle,outercircle,roller,holdingframeonrollingbearings.Theresonancedemodulatesignalisseparatedbyband-passfilterofcenterfrequencyequaltoitsintrinsicfrequency.Thentheenvelopedemodulationiscarriedthroughtothereattenuationoscillatorywaveusingsoftwareorcircuit,thefrequencycomponentofthehighfrequencyattenuationvibrationiswipedoff.Weonlyobtainlow-frequencyenvelopesignalwiththeinformationofthefaultcharacter.ThespectrumanalysisoftheenvelopesignaliscarriedthroughCompoundsensorTemperaturesignalFaultvibrationsignalDSPdigitsignalprocessorEnvelopdetectionEnvelopsignalFrequencybandpassfilterTemperaturesignalprocessingFig.2Signalpretreatmentbydigitalsignalprocessor,wecanobtainveryhighfrequencyresolutionratioandcaneasilyfindthefrequencyofthecorrespondingfaultimpact,therebywecanfulfilltodiagnosetothebearingfault.Withresonancedemodulationtechnology,theelectricresonatorwhichresonantfrequencyismuchhigherthannormalvibrationfrequencyandlimitedhigh-harmonicfrequencyisdesigned.Therefore,itcaneffectivelyrestrainthelow-frequencysignalincludingnormalvibrationsignal.Theresonanceresponsemagnifiesthesignalamplitudeoftheimpulsesignalandthetimeofitsoscillationislonger,thusthefaultsignalisbroadenedinthetimedomainsignal.Aftertheenvelopedetectionandlow-passfilter,thelow-frequencyresonancedemodulationsignalwithhighsignal-to-noiseratioisexported.Inthesignalprocessingsystemshowninfigure2,thebearingcomponentbringsresonanceundertheimpact,formthecontinuousattenuationoscillation.Toresearcheachattenuationoscillation,wecanseethatitsfrequencyisthenaturalfrequencyofbearingcomponents,theamplitudeofattenuationoscillationisrelatetointensityoffaultimpact.Theamplitudeofenvelopesignaloftheattenuationoscillationreflectsthesizeofthefault,andtherepeatfrequencyoftheenvelopedependsonthefaultlocation.Systemhastheperformanceofanti-jammingofthelowfrequencyvibration,highsignal-to-noiseratio.C.EnvelopedetectionAbearingwithfaultinthecourseofrollingwillbringregularvibration.Differentfaulthasdiffer