ABS外文文献及翻译

The6thIEEEInternationalConferenceonIntelligentDataAcquisitionandAdvancedComputingSystems:TechnologyandApplications15-17September2011,Prague,CzechRepublicAnti-LockBrakingSystemBasedonFlexRayProtocolMilosOkrouhly,DenisWarausCzechTechnicalUniversityinPrague,FacultyofElectricalEngineering,Dept.ofMeasurement,Technicka2,16627Prague,@fel.cvut.cz,[e-mail]–Theanti-lockbrakingsystemisnowadaysapartofalmosteveryvehicle.Thissystemincreasessafetyofthepeoplesittinginthevehicleatthemomentofstoppingonaslipperyorunstableroadsurface.Thepointistoassureagoodcontrollabilityofthevehicleevenifthewheelsareinslip.Inordertoworkproperly,theanti-lockbrakingsystemneedstohaveactualinformationabouttherotationofeverysinglewheel.Andtheup-to-datenessandcertaintyofanaccurateinformationistheprimarycriterionofanappropriateperformance.Currently,theinformationaboutthefrequencyofwheelrotationisbeingtransmittedviathecurrentloop.Thissolutionneedsalotofwiring,whichmeansincreasedpurchasecosts.Thispaperdescribesamethod,wheretheinformationfromtherotationsensorsofthewheelsaretransmittedintothecontrolunitthroughtheFlexRaybus.AdditionalwirelessaccelerationsensorslocatedonthewheelareusedtoimprovetheABSperformance.Keywords–Automotiveelectronics;Communicationnet-works;VehiclesafetyI.INTRODUCTIONCurrentvehiclesareequippedwithmanyelectroniccontroldevicesassistingthedriverindailyaswellasemergencysituations.ThedevicesarepartiallyconnectedtoeachotherbyCANnetwork.Complexityandamountofsuchcontroldeviceshassignificantlyrisenduringthelastdecade.Nowadays,theluxurycarscontainmorethanseventyelectroniccontrolunits(ECU)interchangingmorethantwothousandsignals.Upcomingx-by-wiresystemslikeasteer-by-wireorbrake-by-wirethusrequireareliablehigh-speedcommunicationprotocol.ForthispurposeFlexrayprotocolwasdevelopedbytheFlexRayconsorciumwhichincludesleadersoftheautomotiveindustrylikeBMW,GeneralMotoretc.TheFlexRaybuswillbeusedasabackbonenetworkforfuturevehicles.Byusingthebus,theamountofwiring-andsothecosts-canbeessentiallydecreased.ThisresearchissupportedbythetheCzechMinistryofEduca-tion,projectnameJosefBozekResearchCenterofEngineandAu-tomotiveEngineering,grantNo.1M0568,CzechScienceFoundation(GACR),projectnameSensorsandintelligentsensorsystems,grantNo.GD102/09/H082andGrantAgencyoftheCzechTechnicalUniversityinPrague,grantNo.SGS10/207/OHK3/2T/13.Theautomotiveanti-lockbrakingsystem(ABS)isanactivesafetechnologywhichiscurrentlythemostpopularandeffectiveone.AutomotiveABScansignificantlyimprovethedirectionstabilityandsteeringcontrolabilitywhilebrakingandalsoreducethebrakingdistance.Duetoitsgreatcontributiontotheautomotivesafety,furtherresearchofthistechnologyisdesirable.Themaindisadvantageofthecurrentlyusedanti-lockbrakingsystemsappearsduringbrakingonadisruptedroadway.Whenthevehicleisbrakingonthisroadwaytype,thewheelsoftenlosecontactwiththeroadsurface.InthiscasethewheelisblockedduetopressureinthehydraulicsystemandthesituationisclassifiedbytheABSsystemasaslip,sotheABSsystemisactivated.Now,theactivatedanti-lockbrakingsystemopenstheoutputvalve,sothatthepressureinthehydraulicsystemdecreasesandthewheelisthusunblocked.Duetowheelunblocking,thebrakedistanceissignificantlyincreased.Incaseofknowninformationfromtheaccelerationsensorlocatedonthewheelitcanbeassumedthatthewheeldoesnotrotateduetodecreasedclampingforceandcanbelockedbeforeittouchestheroadsurfaceagain.Herebythebrakedistanceisdecreased.TheaimofthispaperistoapplyanewcommunicationprotocoltocurrentABSbyreplacingtheexistingcon-nectionbetweenthesensorsandimproveABScontrolalgorithmbasedonaccelerationobtainedfromwirelessaccelerationsensor.ThenthealgorithmisevaluatedonadevelopedABSplatform.II.FLEXRAYOVERVIEWTheFlexRaycommunicationprotocolisatime-triggeredprotocolwherethedatatransmissionisbasedonrecurringcommunicationcyclewhichiscomposedofstaticsegment,dynamicsegment,symbolwindowandnetworkidletime.Thestaticsegmentcomprisesafixednumberofequallysizedtimedivisionmultipleaccess(TDMA)staticslots.Thesegmentisdesignedforframeswherepredictableframedelayisdefined.Ineachstaticslotaframe(withauniqueidentifierframeID)canbetransmittedbyanode.Onceastaticslotwithauniqueidentifierisallocatedtoa978-1-4577-1425-2/11/$26.00©2011IEEE283specificnode,onlythisnodeisallowedtotransmitduringthisslotandsoprotocolensurescollisionavoidance.Inordertoensureproperslottiming,eachsinglenodeprovidessynchronizationbysynchronizationframes-framewheresynchronizationbitisset.Synchronizationisembeddedinthestandardandisbasedondifferencesbetweenrealandpredictedframereceptions.ThedynamicsegmentemploystheflexibleTDMAapproachandisintendedforthenon-criticalandsporadicmessageswithvaryinglength.ThesymbolwindowisdesignedfortransmissionofCAS(CollisionAvoidanceSymbol),MTS(MediaAccessTestSymbol)orWUS(WakeUpSymbol).TheWUSservesonlyforwakeupofthecluster.TheCASisusedbyacoldstartnode(thenode,whichisconfiguredforsetupofthecluster)toinitializethestart-upprocedure.Duringthelastpartofthecommunicationcycle(i.e.networkidletime),eachnodecancorrecttheoffsetofitsowntimebas