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1、黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)摘要近年來,我國的汽車數(shù)量正逐年增加。在公路、街道、停車場、車庫等擁擠、狹窄的地方倒車時,駕駛員既要前瞻,又要后顧,稍微不小心就會發(fā)生追尾事故。因此,增加汽車的后視能力,研制汽車后部探測障礙物的倒車?yán)走_(dá)便成為近些年來的研究熱點(diǎn)。為此,設(shè)計(jì)了以單片機(jī)為核心,利用超聲波實(shí)現(xiàn)無接觸測距的倒車?yán)走_(dá)系統(tǒng)。工作時,超聲波發(fā)射器不斷發(fā)射出一系列連續(xù)脈沖,給測量邏輯電路提供一個短脈沖。最后由信號處理裝置對接收的信號依據(jù)時間差進(jìn)行處理,自動計(jì)算出車與障礙物之間的距離。目前,國內(nèi)外一般的超聲波測距儀,其理想的測量距離為1m~5m,因此大都用于汽車倒車?yán)走_(dá)等近距離測距中。本文根據(jù)聲
2、波在空氣中傳播反射原理,以超聲波換能器為接口部件,介紹了基于STC89C51單片機(jī)的超聲波倒車?yán)走_(dá)。該設(shè)計(jì)由超聲波發(fā)射模塊、信號接收模塊、單片機(jī)處理模塊、數(shù)碼顯示以及聲光告警顯示模塊等部分組成,文中詳細(xì)介紹了倒車?yán)走_(dá)的硬件組成、檢測原理、方法以及軟件結(jié)構(gòu)。超聲波接收電路使用SONY公司的CX20106A紅外檢測專用芯片,該芯片常用于38kHz的檢波電路,文中通過對芯片內(nèi)部電路的仔細(xì)分析,設(shè)計(jì)出能夠成功對40kHz超聲波檢波的硬件電路,倒車?yán)走_(dá)使用數(shù)碼管顯示目標(biāo)物的距離。關(guān)鍵詞:STC89C51;倒車?yán)走_(dá);超聲波傳感器;測距Ⅱ黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)ABSTRACTInrecentye
3、ars,China'snumberofcarsisincreasingeveryyear.Highways,streets,parking,garageandothercrowdedplacesnarrowreverse,thedrivershouldnotonlyforwardbutalsolookingback,alittlerear-endcarelessaccidentscanoccur.Soaftertheincreaseofmotorvehiclesastheabilitytodetectobstaclesonthedevelopmentoftherearofthecarre
4、versingradarhasbecometheresearchhotspotinrecentyears.theultrasonictransmittercontinuouslyemitsaseriesofconsecutivepulsestothemeasurementoflogiccircuitstoprovideashortpulse.Finally,signalprocessingdevicesbasedonthereceivedsignalforprocessingthetimedifference,automaticcalculationofturnoutandthedist
5、ancebetweenobstacles.UltrasonicRangingsimple,lowcost,easyproduction,butthetransmissionspeedbyalargerweathercannotbepreciserange;Inaddition,theultrasonicenergyandtheattenuationisdirectlyproportionaltothesquareofthedistance,thefartherthedistance,thelowersensitivityandthusUltrasonicRangingwaysothato
6、nlyapplytoashorterdistance.Atpresent,ultrasonicrangefinderathomeandabroadingeneral,theidealdistanceofthemeasurement1~5m,basedonSTC89C51ultrasonicrange-finder.ReceivingcircuitusingtheSONYcompanydedicatedCX20106Ainfrareddetectingchip,thechipusedinthedetectorcircuit38KHz,thetextofthechipthroughtheca
7、refulanalysisoftheinternalcircuitdesigncansuccessfully40kHzultrasonicdetectionofhardwarecircuitryandadjustablegain,Theuseofdigitalrangefinderdisplaythedistancebetweenobjects.KEYWORDS:STC89C51;Wave;Measure;DistanceRever