毕业论文外文翻译基于ARM与线性CCD的高速数据采集系统.docx

毕业论文外文翻译基于ARM与线性CCD的高速数据采集系统.docx

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毕业论文外文翻译基于ARM与线性CCD的高速数据采集系统

毕业设计

中英文翻译

机电工程学院

学生姓名：

学号：

探测制导与控制技术

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专业：

指导教师：

2012年6月

High–SpeedDataAcquisitionSystemBasedonARM&Linear-CCD

DongJianjunZhaoXiaojin

Dept.Four,TheFirstAeronauticalTechnicalCollegeoftheAirForceXinyang464000.China.

Abstract:

Thispaperpresentsahighspeedacquisitionsystemoflinear-CCDbasedonARM,high-speedlinear-CCDandhigh-speedADCareselected.AsthesamplingspeedofA/DisslowerthantheworkingclockfrequencyofARM,CPLDandFIFOareusedasI/ObetweenA/DandARM.Itmakesthecircuitworksharmonious,simpleandeasycontrolling,andalsoincreasestheefficiencyofARM.Inordertoincreasethecommunicationspeed,theUniversalSerialBus（USB）technologyisadoptedtocommunicatewiththePC.ARMisthekeyprocessorutilizedtocontrolthedatasampling,datacomputeanddatatransfer.Asaresult,thewholesystemworkseffective.Thesystemcanbeappliedtothehighspeeddataacquisitionandoperationsituationsfrommulti-channelanalogsignals.

KeyWords:

ARM;LinearCCD;Contact-line;Pantograph;Stagger–value

I.Introduction

Inelectrificationrailways,inordertoextendthelifeofthepantographonelectriclocomotives,sothatthesliderofpantographwearevenly,thecontact-line（electrifiedrailwaypowerfeedline）instraight-linesegmentsisarrangedaszigzagroute（curvesectionarrangedintheformofpolyline）.Thedistancebetweenthecontact-lineofpositioningpointandthepantographcenterlinetrackiscalledoutstagger-value,whichisakeyindicatorofcontact-line.

Stagger-valuecannotbeignored,thevaluetoosmallwillaffectthesliderofpantographwearevenlyandthepurposeofextendingusinglife;otherwise,insomecases（suchascaughtinastiffwinds）,causealargerangeoflateralmovementoftheroof（andthehigherthespeed,thegreaterpantographswingaround）,somepartsofcontact-linewillbeinexcessoftheeffectiveworklengthofpantograph,sothatthestagger-valueofcontact-linebeyondthestandardrange,leadingtodeteriorationofthecurrentcollection,andevencauseincorrectrunningofthepantographaccident.Pantograph-catenarymalfunctionwillresultininterruptionoftrainoperation,whichimpactonrailtransportseriously.Inordertoavoidthesephenomena,thestagger-valueanditschangesshouldbetestedregularly.Therefore,alocomotivecontact-linemonitoringsystemanditsmatingdataacquisitionsystemweredeveloped,whichcalculatetheinstantstagger-valuequickly.

II.SystemComponents

Systemhardwarecomponentsareshowninfigure1.

Thesystemconsistsofthefollowingcomponents:

（1）usingTOSHIBACompany’shigh-speedlineararrayCCDtoachievethedigitizationofcontact-lineimages（CCDoutputthesignalofcorrespondingtimesequenceofposition）;

（2）usingAtmelCompany’sAT91RM9200processorofARM9seriestorealizedigitalsignalacquisitionandprocessing;（3）usingPDIUSBD12USBinterfacedevicetocompletethedatacommunicationsbetweenmeasurementsystemandthePC.

DuetothecharacteristicsofitsimprovedHarvardstructure,specialinstructionsandquicktorealizeavarietyofsignalprocessing,ARMprocessoriswidelyusedinimageprocessing,communications,radar,sonar,precisionmachineryfields,etc.ARMprocessorisadoptedforitsarithmeticspeedandbuswidth.Asthereal-timesignalanalysisandcalculationrequireahighspeedofcomputing,AtmelCompany’sARMchip—AT91RM9200isselected.ThechipisARM920Tbased,high-performance,lowpowerconsumption16/32-bitRISC（reducedinstructionsetcomputer）microcontroller,whichincorporatesarichsetofapplicationperipheralsandprovideasingle-chipsolutionforindustrialcontrolapplicationsthatrequireawiderangeofperipheralsatlowpowerconsumptionandstrictlystableworking.

Fig1Systemblockdiagram

.Real-timeprocessingandtransmissionofCCDdigitalimage

Inordertoachievereal-timedigitalimage

transmission,severalmajorfactorswhichaffectreal-timetransmissionshouldbenecessarytosolve:

First,thespeedoflineararrayCCDdataacquisition;Second,thetransmissionspeedbetweenlineararrayCCDandARMprocessor;thethirdisthedatatransmissionspeedbetweenARMprocessorandcomputer.Thefollowingwillbedescribedindetail.

A.LineararrayCCDacquisitionspeed

Acquisitionspeedisacriticalperformanceindicatorforimagesensor,TOSHIBACompany’sTCD1209DlineararrayCCDisusedtomeetthetargets.Itsclockpulsefrequencycanoperateashighas20MHz,especiallysuitableforhigh-speedconditionsofsizemeasurementanddynamicanalysis.

Fig2LinearCCDTCD1209Danditstimesequencediagram

LineararrayCCDTCD1209Danditstimesequencediagramareshowninfigure2.

B.TransmissionspeedbetweenCCDandARMprocessor

InordertoimprovethespeedofCCDdataacquisitionandreduceconversiontime,adoptinghighspeedA/DconvertercanmakeitexchangedatawithARMprocessorathigh-speed.ADC08200,AnalogCompany'snanosecondconversiondeviceisadopted.It’sasingle-channel,8-bitA/Dconverter,whichoperatesoverawiderangeoftemperature,convertsfast,operatesatconversionratesupto230MSPS,thusachievingentiresignalacquisitionoflineararrayCCD.ADC08200isshowninfigure3.

Fig3High-speedA/DconverterADC080200

FIFOisusedasadatabuffertoco-ordinatetherateofARMprocessorandADC.Itisatwo-port（inputandoutputport）memoryfortemporarystorageoffirstinfirstoutdata.DuetothetimetowritedatatoFIFOisfarlessthantheA/Dconversiontime,therefore,theacquisitionspeeddependsontheA/Dconversionspeed.

Inordertoimprovethespeedoftheentiremeasurementsystem,thetimesequenceofentirecircuitispreciselycontrolledbytheCPLDtomakethecircuitworksharmonious.CCDdrivingsignal,integrationtimecontrol,addressdecoding,A/Dconversioncontrol,databufferanddataacquisitionlogicfunctionsintegrateintheCPLD,sothattheentirecircuitstructureissimpleandreliable.

Inordertofurtherenhancethesystemspeed,whenthesystemstarts,systemprogramsaretransferredtohigh-speedSRAMforrunningandSDRAMfordatastorage;SRAM,SDRAMshouldbeplacedascloseaspossibletoARMprocessors,andthesignallinestheshortestpossible.

ARMprocessor（AT91RM9200）,thesignalprocessingcoreoftheentirehardwaresystem,readtheCCDlightintensitysignalfromFIFO,calculatethedistributionofcontact-lineimageintheCCDwithcorrespondingalgorithm,andtransfertheresulttotheslavecomputerthroughUSB.

C.TransmissionspeedbetweenARMprocessorandcomputer

Inordertoincreasethespeedofdatatransmissionandreducetransmissiondelay,USBinterfaceisusedfordatatransmission.USB1.1interfacesupportlow-speedandfull-speedtransmission,datatransferrateshasreached1.5Mbpsinlow-speedmode,thetransmissionspeedupto12Mbpsinfullspeedmode.PhilipsCompany’sPDIUSBD12isadopted.

WhenaUSBdeviceinsertedintothePC,PCenumeratesUSBdeviceautomatically.Whendetectingequipmenttoinsert,PCsendqueryrequest.USBdevicesrespondtotherequestandsendequipmentVendorIDandProductID;PCloadsthecorrespondingdevicedriverwiththesetwoIDtocompletetheenumerationprocess.

PC-sideUSBdevicedriveriscompletedbyWinDriver.DatacommunicationbetweenPCandUSBequipmentmainlyincludestwoaspects:

first,readthesampledata;second,sendcontrolcommandstotheacquisitionsystem.

IV.CCDimagerecognitionalgorithm

ARMprocessorismainlyresponsibleforthesolutionofstagger-value;it’stheprocessofimageidentification,includingbackgroundseparationandfeatureextractionoftheimagedata.Identificationoftheimageisforimagegrayonly;thestandarddeviationthresholdtrackingmethodisadopted.Theimageiscomposedofblack-and-whitetexture,andgray-scalevariesgreatly,withalargerstandarddeviation;andbackgroundgraydistributionisrelativelyflat,withsmallstandarddeviation.Therefore,thestandarddeviationofeachpointasthecenterofagroupofpixelsiscalculated,thevaluegreaterthanacertainthresholddeterminethepointintheforeground,orasthebackground.

Thissystemnotonlymeasuresthecontact-lineinstantposition,butalsocalculatestheabrasionstateofthecontact-linetoevaluateitslifespan.SystemsupportbyassociatedPCsoftware,throughsubsequentplaybackofthedatacollected,tocheckthesituationofstagger-value,aswellastheabrasionofcontact-line,anddecidewhethertoadjustandreplaceornot

V.Measuresofimprovingsystemreliability

High-speeddataacquisitionsystemisinevitablyaffectedbyinterferencefromtheexternalenvironment.Asthecomplexenvironmentaroundthemeasurementsystem,manyfactorsinterferewiththesystem.Electromagneticinterferencearound27.5KVhigh-voltagecatenaryaffectsgreat;thepantographdetachingwillbeaccompaniedbytheemergenceofarcsparks,thisphenomenoninterferewithcommunicationlinealongthelines,accompaniedbyhigh-frequencyelectromagneticwaves,therefore,necessaryanti-interferencemeasuresshouldbetaken.Inordertoimprovetheabilityofanti-interference,anti-jammingmeasurestakenareasfollows:

takeanti-interferencedesignofPCBcircuittoreducetheexternalinterferenceonsystem;allcablesadoptshieldedcablewithwave-proofsleeve;equipmentshelladoptsshieldingmaterialanddetectionwindowoftheshellusegauzetoisolatetheinterference.

VI.Results

Wehaveusedthishigh–speeddataacquisitionsysteminWuhansouthlocomotive-depottomeasurethecontact-lineinstantposition,andthetestresultshowsthatthewhole