某轿车动力装置参数的匹配设计英文翻译毕业论文.docx
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某轿车动力装置参数的匹配设计英文翻译毕业论文.docx
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某轿车动力装置参数的匹配设计英文翻译毕业论文
某轿车动力装置参数的匹配设计英文翻译毕业论文
Abstract
Theavailabilityofpressureinformationofahydraulicactuatormakesitpossibletoimprovethequalityofvehiclepowertransmissionviaprecisefeedbackcontrolandtorealizeon-boardfaultdiagnosis.However,thehighcostofapressuresensorhasnotalloweditswidespreaddeploymentdespitesuchapparentadvantages.Thispaperpresentsanobserver-basedalgorithmtoestimatethepressureoutputofahydraulicactuatorinavehiclepowertransmissioncontrolsystem.Theproposedalgorithmbuildsonmorereadilyavailableslipvelocityandthemodelsofahydraulicactuatorandamechanicalsubsystem.Theformerisobtainedempiricallyviasystemidentificationduetothecomplexityofthehydraulicactuator,whilethelatterisderivedphysically.Theresultingrobustobserverisguaranteedtobestableagainstpossibleparametricvariationsandtorqueestimationerrors.Thehardwarein-the-loopstudiesdemonstratetheviabilityoftheproposedalgorithminthefieldofadvancedvehiclepowertransmissioncontrolandfaultdiagnosis.C2002ElsevierScienceLtd.Allrightsreserved.Received1March2001;accepted27August2001
Keywords:
Robustobserver;Systemidentification;Hydraulicactuator;Vehiclepowertransmissioncontrolsystem;Hardware-in-the-loopsimulation
1.Introduction
Automaticandcontinuouslyvariabletransmissionsystemshavebeenexpandingtheirpresenceinpassengervehiclesinrecentyears,whichhasnaturallypromptedactiveresearchonvehiclepowertransmissioncontrolsystems.Themaintopicsincludeshiftcontrolalgorithm(Shin,Hahn,Yi,&Lee,2000a;Zheng,Srinivasan,&Rizzoni,1999;Shin,Hahn,&Lee,2000b),feedbackcontroloftorqueconverterclutchslipsystems(Jauch,1999;Hibino,Osawa,Yamada,Kono,&Tanaka,1996;Hahn&Lee,2000),newhydrauliccircuitsforcontrolperformanceenhancement(Jung,Cho,&Lee,2000),etc.Despitetheextensiveresearcheffortoncontrolalgorithms,itappearsthatthepressureinformationofahydraulicactuatorhasnotbeenfullyutilizedinvehiclepowertransmissioncontrol,largelyduetothehighcostofapressuresensor.Asaresult,mostpracticalcontrollershavebeenlargelybuiltuponthemechanicalsubsystemonly,whileneglectingthedynamicsofahydraulicactuator.
Insteadofdirectlymeasuringthepressureoutputofahydraulicactuator,thispaperproposesanindirectalternativetoestimatethepressureoutput:
anobserver-basedapproach.Themainthrustofthispaperisthatthepressureoutputofahydraulicactuatoris‘observable’withtheslipvelocitymeasurementofthemechanicalsubsysteminavehiclepowertransmissioncontrolsystem.Inadditiontothereadilyavailableslipvelocitymeasurement,theobserverdesignrequiresthemodelsofhydraulicandmechanicalsubsystemswhoseaccuracydirectlyimpactstheobserverperformance.Themechanicalsubsystemisphysicallymodeledwithrelativeease.Thecomplexityofthehydraulicactuatordynamicsdoesnotallowaphysicalmodelamenabletoobserverdesign.Instead,systemidentificationyieldsasimplifiedempiricalmodelofthehydraulicactuator.Actualobserverdesignfocusesonguaranteeingrobuststabilityagainstparametricvariationsandtorqueestimationerrorsthatareboundtooccurinamechanicalpowertransmissioncontrolsystem.Hardware-in-the-loopsimulationstudiesareconductedtoexaminetheperformanceoftherobustobserver-basedestimatorforthehydraulicactuatorpressure,whichshowstheviabilityoftheproposedapproach.Theoutcomeisarobustpressureestimatorthatreliesonthereadilyavailableslipvelocitymeasurementonlyandthushasapotentialtobewidelyemployedinvehiclepowertransmissioncontrolandfaultdiagnosis.
Thispaperisorganizedasfollows.Section2derivesaphysicalmodelforthemechanicalsubsystem.SimplifiedempiricalmodelsaredevelopedforahydraulicactuatorinSection3.Section4dealswiththeobserverdesign.TheperformanceofthedesignedobserverisexaminedinSection5.
2.Overviewofavehiclepowertransmissioncontrolsystem
Avehiclepowertransmissioncontrolsystemtypicallyconsistsoftwosubsystems,amechanicalsubsystemandahydraulicactuator.Theinputandoutputofthesystemunderconsiderationarethevoltagesignaltothehydraulicactuatorandtheslipvelocitybetweenthefrictionelementsinthemechanicalsubsystem,respectively.Thehydraulicactuatordrivesthefrictionelementsandgeneratestheslipvelocityofthemechanicalsubsystemaccordingtoitspressureoutput.Fig.1showsavehiclepowertransmissioncontrolsystemconsideredinthispaper,atorqueconverterclutchslipcontrolsystem.Themechanicalsubsystemconsistsofanengine,atorqueconverter,anautomatictransmissionwithplanetarygearsets,andwheelswithafinalreductiongear.Thetorqueconverterclutchgeneratesfrictiontorqueactingupontheengineaccordingtothehydraulicactuatorpressure,whichinturndeterminestheslipvelocitybetweentheengineandtheturbineofthetorqueconverteratadesiredtargetvalue.
Inordertoderiveaphysicalmodelofthemechanicalsubsystem,thepowertransmissionateachstageisexamined.Attheveryfirststage,theenginetorqueistransmittedtotheimpellerandisbalancedbythereactiontorqueoftheimpellerandthefrictiontorquefromthetorqueconverterclutch.Thetorqueconverteramplifiesandtransmitstheimpellertorquetotheturbine.Theturbinetorquedrivestheautomatictransmissionsystemtogetherwiththefrictiontorqueofthetorqueconverterclutch,whilethedrivingloadtorqueofthevehicleprovidesadditionalresistiveforce.Denotingtheslipvelocitybetweentheengineandtheturbineastheoutputofinterest(y)resultsinHahn&Lee(2000)
whereIeistheequivalentrotationalinertiaoftheengine,Ivtheequivalentrotationalinertiaofthevehicle,Wetheangularvelocityoftheengine,Wttheangularvelocitytheturbine,Tetheenginetorque,Tptheimpellertorque,Tttheturbinetorque,Tcthefrictiontorqueofthetorqueconverterclutch,Tlthedrivingloadtorque,ctheequivalentdampingconstantofthetorqueconverterclutch,rtthegearratiooftheautomatictransmission,rfthegearratioofthefinalreduction,mthefrictioncoefficientofthetorqueconverterclutch,Rotheouterradiusofthetorqueconverterclutch,RitheinnerradiusofthetorqueconverterclutchandPcthepressureoutputofthehydraulicactuator,Itisworthnotingthatthequantitiesin
Eq.
(1)aresubjecttoerrors;thedampingconstantisnotexactlyknown;absenceoftorquesensorsinacommercialvehicleentailstorqueestimationerrors;theequivalentrotationalinertiaofthevehiclevariesasthenumberofpassengerschanges,andonlyaroughboundonthefrictioncoefficientisavailable.
3.Identificationofahydraulicactuator
3.1.Motivationforempiricalmodeling
Fig.2showsthehydraulicactuatorconsideredinthispaper.Itbasicallyconsistsofthreeelements:
aPWMtypesolenoidvalve,apressuremodulatorvalveandapressurecontrolvalve.Thefirstandsecondregulatingvalves,notshowninFig.2,regulatesthemainpressureoftheentirehydrauliccircuit.Thepressuremodulatorvalvefurtherdecreasestheoutputpressureofthefirstregulatingvalve(channel#7)toalowerpressurelevel.
Theoutputpressureofthepressuremodulatorvalveatchannel#9isalwaysregulatedaround4.0barinthesteady-statebymeansofthefeedbackchamber#10(Hahn,1999).Thevoltagesignalfromthetransmissioncontrolunit(TCU)drivesthePWM-typesolenoidvalvesothatthepressureatchannel#11assumesvaluesbetween0barand4bar.Thepressureatchannel#11actsonthespoolofthepressurecontrolvalve,whichinturngeneratesengage/disengagepressuresforthefrictionelementinthemechanicalsubsystem.Sincetheengage/disengagepressuresareappliedtothesamefrictionelementfromtheoppositesides,thedifferencebetweenengageanddisengagepressuresmayberegardedastheoutputofthehydraulicactuator.
AnonlinearmathematicalmodelofthehydraulicactuatorhasbeenobtainedinHahn(1999)usingtheNewton’ssecondlawofmotion.AlthoughthenonlinearmodelinHahn(1999)matchestheexperimentalresultstoacertainextent,ithassomedrawbackswhenappliedtotheobserverdesignproblemconsideredinthispaper:
1.Themodelorderistoohigh(E10).
2.Thegoverningdifferentialequationsaretoostifftonumericallysolveinreal-time.
3.Thereexistnumerousunknownparametersthatneedtobeestimatedortunedinordertoobtainreasonablematchbetweenexperimentalresultsandmodelpredictions.
Apossiblealternativeistocapturethedynamicsessentialtothedesignofanonlinearobserverandtoobtainalower-ordercontrol-orientedempiricalmodel.Inthispaper,twoempiricalmodelsareproposedbasedonthesystemidentification(Ljung,1999).
1.Nonlinear.
2.Mostlysmooth,althoughitsbehaviorisqualitativelydifferentatacoupleofpoints,i.e.nearlydiscontinuous.
3.Notone-to-onewhenthedutycycleisaround60%.
4.Notevensymmetricwithrespecttoorigin;60%dutycycleapproximatelycorrespondsto0barpressureoutput.
Theseobservationsraiseanimmediateconcernthatthebrute-forceapplicationofsystemidentification(Ljung,1999)mayutterlyfailtogiveahigh-fidelitymodelifaconventionalmodelstructure,e.g.,ARX(auto-regressivewithexogenousinput)isadopted.Inthesteady-state,anARXmodelapproximatesthenonlinearmappinginFig.3byastraightlinepassingthroughtheorigin,byvirtueofitslinearity.Abetterapproachwouldbetoshifttheorigintoapointaroundwhichtheinput–outputmappingisapproximatelysy
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- 轿车 动力装置 参数 匹配 设计 英文翻译 毕业论文