出租车计价器毕业设计方案中英文翻译Word格式文档下载.docx
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出租车计价器毕业设计方案中英文翻译Word格式文档下载.docx
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ispresented.
Systemlocation,outline,blockdiagramsaswellasdetailedcircuitdiagramsfortheexperimentaltaximeterarealsoincluded.
1.INTRODUCTION
Transportingpeopleinthemorningfromtheirhomestotheirworksandbackintheafternoonhasbecomeabigprobleminbigcitiesespeciallyinundevelopedcountries.Asapartialsolutionofthisproblem,theauthoritiesinsomecountrieshad,unofficially,leftthetaxicabdriverstocarrydifferentpassengerstodifferentplacesattheSametime.Forexample,ataxicabwithfourseatsmaycarryfourdifferentpassengerswithoutanyrelationbetweenthemexceptthattheirwayoftravellingisthesame.
Accordingly,ithasbecomeverydifficulttorelyonthepresentconventionalsingle-channeltaximetertodeterminethefarerequiredfromeachpassengerseparately.Accordingly,anunfairfinancialrelationwascreatedbetweenthetaxicabdriver,owner,passengersandthestatetaxationdepartment.
Underthesecircumstances,taxicabdriversforcethepassengerstopaymorethanwhattheyshouldpay.Insomecasespassengershadtopaydoublefaretheyshouldpay.Withthepresentconventionalsingle-channeltaximeter,taxicabownersarenotabletodeterminethedailyincomeoftheirtaxicab.
Insomecases(ataxicabwithfourseats>
theymayonlygetonequarteroftheincomeofthetaxicab(collectedbythetaxicabdriver>
.Fromwhichtheyshouldpaythesalaryofthetaxicabdriveraswellasthecostoffuel,minorandmajorrepairsinadditiontothecardepreciation.Asamatteroffactthepositionofthetaxicabownersisnotsobadasitseems.Ageneralagreementhasbeenreachedbetweenthetaxicabdriversandownerssuchthatthedriversshouldguaranteeafixeddailyincometotheownersaswellasthepayingforthecostoffuelaswellastheminorrepaires.Eventhoughthetaxicabdriversstillsharethelargeportionoftheincomeofthetaxicab.Alsowiththepresenceofthesingle-channeltaximeter,ithasbecomeverydifficultforthestatetaxationdepartmenttoknowtheyearlyincomeofthetaxicabandaccordinglyithasbecomeverydifficulttoestimatethetaxestobepaidbythetaxicabowners.
Inordertofacethisproblem,thestatetaxationdepartmenthadtoimposeafixedestimatedtaxesforeachseatofthetaxicabwhatevertheincomeofthetaxicab.Inthispaper,weintroducedamultichanneltaximeterthatcandealwithmorethanonepassengersimultaneously.Itshouldbepointedoutthatbythetermpassengerwemeanaonepersonoragroupofrelatedpersons.Itshouldalsobepointedoutthatourproposedmulti-channeltaximeterisnot,simply,amultidisplayreadouts.Asamatteroffactitcontainslogiccircuitsthatautomaticallychangesthefareperkillometeroftravellingdistanceorperminutesof'
waitingtimeaccordingtothenumberofpassengershiringthetaxicab.Inthefollowingpartandasanexample,wewillpresentacompletedesignforathree-channeltaximeter.
Blockdiagramsaswellasdetailedcircuitdiagramsoftheexperimentalthree-channeltaximeterarealsoincluded.AprototypehasbeenbuiltundergrantfromtheEgyptianAcademyforScientificandTechnologicalResearch.
2.ANEXPERIMENTALTHREECHANNELTAXIMETER
Theoryofoperationofourexperimentaldevicetoworkasanelectronicdigitaltaximeterisbasedonthefactthathespeedometercablerotatesonerevolutionforeachmeteroftravellingdistance.
Accordingly,ifthespeedometercableiscoupledwithaspeedsensorthatgeneratesasinglepulseforeachmeteroftravellingdistance,thenourtaximetercouldbethreeupcountermodulesassociatedwithaspeedsensorunit.
However,ourexperimentaltaximeterisnotsimplyathreedisplayreadouts.Asamatteroffactitcontainslogiccircuitsthatautomaticallychangesthefareperkilometeroftravellingdistanceorperminutesofwaitingtimeaccordingtothenumberofpassengershiringthetaxicab.Thedevicemaybesplittedintotwomainparts:
Thefirstisthespeedsensorunitwhichmaybelocatedanywhereinthetaxicabsuchthataneasycouplingtothespeedometercablecanbeachieved.Thesecondunitcontainsthemainelectroniccircuit,thedisplayandcontrolpanel.Theunitshouldbelocatedsomewhereinfrontofboththedriverandthepassengers.
ApossiblecomponentslocationsisshowninFigure1.
A.SpeedSensorUnit
Themainfunctionofthisunitistosupplytrainofpulseswhosefrequencyisproportionaltotheangularrotationofthewheels.ApossibleformofaspeedsensorisshowninFigure2.
Ifmayconsistofatj.pica1permanentmagnetsinewavegeneratorwithitsoutputconnectedtoapulseshappingcircuit(twogeneralpurposesilicondiodes,1Kohmsresistorandaschmittriggerinverter>
.
Inordertofindsomewaytodetectthemovementofthetaxicab,theoutputofthesinewavegeneratorisrectifiedthroughageneralpurposesilicondiodeDlthensmoothedbya1000Fcapacitor.TheoutputvoltageatterminalQisthenlimitedtothevalueof4.7voltsbyusingaIkohmsresistoraswellasazenerdiodeZD.ThelevelofthevoltageatterminalQwouldbehighwheneverthetaxicabismovingandwillbezerootherwise.Thisvoltagecanbeusedfortheautomaticswitchingfromdistancefaretotimefare.
B.MainElectronicandDisplayUnitAsuggestedshapeforthemainelectronicand
displayunitisshowninFigure3.Thecontrolanddisplaypanelcontainsall'
controlsnecessaryforoperatingthetaximeteraswellasfourreadoutdisplays.Thefirstchannelwillgivethesumofmoneyrequiredfromthefirstpassenger,whilethesecondandthirdreadoutsareforthesecondandthirdpassengers,respectively.Thefourthreadoutwillgivethetotalincomeofthetaxicab.
Thecontentsofthelastreadoutshouldbenonvolatileandbeabletoberetainedevenduringparkingthetaxicab.Thechannelrotaryselectorswitchs1,2and3havefullyclockwise/anticlockwisepositions.Inthefullyanticlockwiseposition,thecounterofthecorrespondingreadoutisblanckedanddisabled.
Inthefullyclockwiseposition,thecounterisunblanked,clearedtozeroandenabledtobereadyforcountingthesumofmoneyrequiredfromthefirst,secondandthirdpassengers,respectively.
Pushingthetotalsumpushbutton4unblanksthefourthreadoutenablinganypersontoretainthereadoutcorrespondingtothetotalincome.Afterthereleaseofthepushbutton,thefourthreadoutwillbeblankedagain.Thisunitalsocontainsthemainelectroniccircuitwhichwillbefullydescribedinthefollowingsection.
3.DESCRIBTIONOFTHEMAINELECTRONICCIRCUIT
ThegeneralblockdiagramofthemainelectroniccircuitisshowninFigure4.ItconsistsoffivesubcircuitsdesignatedbythesymbolesCTIuptoCT4supportingcircuits,theseare:
ThenumberofpassengerdeticitioncircuitCTI,travellingdistancescalingcircuitCT2,waitingtimescalingcircuitCT3,circuitCT4whichgeneratesclockpulsesforthedisplaycircuit.
A.NumberofPassengersDetectionCircuitCT1Asshownfromthegeneralblockdiagram,thecircuitCTIhasthreeinputsI,2and3aswellasthreeoutputsJ,KandL.ThefunctionofthecircuitistosupplyahighlevelvoltageatterminalsJ,KorLifandonlyifone,twoorthreepassengersarehiringthetaxicab,respectively.Thetermpassenger,here,meansonepersonoragroupofrelatedpersons.Whenapassengerisgettingintothecab,wesimplyturnonafreereadoutdisplaybyturningthecorrespondingrotaryselectorswitchtoafullyclockwisedirection.
ThiswillautomaticallydisconnectthecorrespondingterminalI,2or3fromground.ThelogicalrelationbetweenvariousinputterminalsI,2and3andtheoutputterminalsJ,KandLisshowninTable1.
Asacombinationalcircuitwestartthedesignbyderivingasetofbooleanfunctions.ApossiblesimplifiedbooleanfunctionsthatgivesminimumnumberofinputstogatesmaybeobtainedfromTableI.
ApossiblelogicaldiagramthatisbasedontheabovederivedexpressionsisshowninFigure5.
Itconsistsoftwoinverters,four2-inputAND,to3-inputANDtwo3-inputORgatesB.TavellingDistanceScalingCircuitCT2
AsshownfromtheblockdiagramofFigure4,thecircuitCT2hasfourinputJ,K,LandEandoneoutputM.ThefunctionofthecircuitistosupplyasinglepulseattheoutputMforacertainnumberofpulsesgeneratedattheoutputofthespeedsensor(certainnumberofmeterstravelledbythetaxicab>
accordingtothenumberofpassengershiringthecar.AsuggestedfareperkilometeroftravellingdistanceisshownincolomntwoofTable2.thecircuit,inthiscase,shouldsupplyasinglepulseattheoutputMforevery100,125or143pulsesgeneratedattheinputterminalE
accordingtothelevelofvoltageatinputterminale3,KorL,respectively.
Ourcircuitcouldbe,asshowninFigure5,threedecadecounters,connectedasathreedigitfrequencydividerwhosedividingratios100,125and143areautomaticallyselectedbythevoltagelevelatterminalsJ,KandL,respectively.
ApossiblecircuitdiagramthatmayverifytheabovefunctionisshowninFigure6.Itconsistsofthreedecadecounterstype7490,oneBCD-todecimaldecodertype7445,three4-inputAND,one3-inputANDone2-inputANDtwo3-inputORgates.
C.TimeScalingCircuitCT3
Asshownintheblockdiagram,thetimescalingcircuitwillhavefourinputsJ,K,LandFand
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