SAE J1574-2-2000 Measurement of Vehicle and Suspen

SAETechnicalStandardsBoardRulesprovidethat:“ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser.”SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmaybereaffirmed,revised,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.TOPLACEADOCUMENTORDER:[phone]FAX:[phone]SAEWEBADDRESS—RationaleForeword—WhilethetheoreticalfundamentalsofprimaryridehadbeenestablishedbyRowell[1]1in1922,thefirstguidelinesforstaticdeflectionsanddynamicindexwereprovidedin1934byOlley[2].Olleyalsoprovidedthefirstmeasurementsofdirectionalcontrolperformancethroughhisconceptofundersteerandoversteer.Meanwhile,Lutz[3]wasusingone-tenthscalemodelstostudydirectionalcontrol.Earlytheoreticalstudiesofdirectionalcontrolweregenerallysimplified,suchasthoseofHuber[4]andRiekertandSchunk[5]in1940.ThefirstdynamictransitiontestwasreportedbyStonex[6]in1941,usinganopticalmethodtodeterminethepathofthevehicle.In1953,Fonda[7]developedamorecompletelinearmodelbyusingstabilityderivativenotationfromaircraftpractice,andSchilling[8]calculatedtransientresponse.Earlymeasurementofvehicleandsuspensioncharacteristicswastypicallystraightforward,sometimescrude;Olleyusedpairsofjacksandscalestomeasurerideandrollratesandacabledrivenrotaryscaletomeasureaxlesteer,forexample.A1938workbyKammandSchmid[9]includesillustrationsofthetestequipmentusedtomeasurespringrates,Coulombfriction,shockabsorbercharacteristics,steeringsystemcompliance,centerofgravitylocation,andpitchmomentofinertia.Theseearlymeasurements,evenifsufficientlyaccurate,appeartohavebeenquitelaborintensiveandtimeconsuming.Facilitiesforconvenient,systematicmeasurementofvehicleandsuspensionparametersareapparentlyrelativelyrecent,suchasthosedescribedbyNedleyandWilson[10],EllisandSharp[11],Basso[12],Winkler[13],andBell,et.al.[14,15].Otherresearchers[16,17,18]haveaddressedotheraspectsofvehicleandsuspensionparametermeasurementandcharacterization.1.Scope—ThisSAEInformationReportpresentsthebackgroundandrationaleforSAEJ1574-1.Themotorvehicleindustryisworkingtowardamorecompleteunderstandingofthefactorsaffectingthemotionsofvehiclesontheroadway,byusingavarietyoftechniquesthatpredictresponsestoroadandoperatorinputs.Thecapabilitytopredictresponsesisdesirablesothatvehiclescanbedesignedforoptimumsafetyandutility.Inadditiontotheforceandmomentpropertiesofthepneumatictires,anumberofvehicleandsuspensionparametersaffecttheresponseofthevehicle;theseincludeweight,center-of-gravitylocation,momentsofinertia,suspensionrideandrollrates,suspensionkinematicandcomplianceproperties,andshockabsorbercharacteristics.Theseparametersmustbequantifiedinordertopredictvehicleresponses.1.NumbersinparenthesisdesignatereferencesinSection2.SAEJ1574-2RevisedMAR2000-2-Measurementofmostoftheseparameterswillbelimitedtodeterminingtheirvaluesinthelinearrangeforuseindirectionalcontrolsimulations.Thelimitationtolinearrangecharacteristicsprimarilyreflectscurrentmeasurementpractice,towhichSAEJ1574-1isdirected.Inthecaseofmassandinertiaproperties,thislimitationclearlydoesnotapply.Forthosetowhichitdoesapply,itisnotfelttobeaseriouslimitationsincemostofthemeasurementtechniquescanbeextendedbeyondthelinearrangethroughappropriateincreasesinsteeringorsuspensiondisplacementorloading.Useofthemeasuredparametersinsimulationsisassumedasthemostfrequentuse.However,thisdoesnotseemtolimittheirusetosimulations.Vehicleandsuspensioncharacteristicsappropriateforsimulationcanequallywellbeusedforvehicleandsuspensioncharacterizationandcomparison,suspensiondevelopmentandoptimization,andprocessingofroadtestdata.AsnotedinSAEJ1574-1,vehiclesaddressedwillbelimitedtopassengercars,lighttrucks,andon-highwayrecreationalandcommercialvehicleswithtwoormoreaxlesofapproximatelythesamewheeltrack.Thisexcludesbicycles,motorcycles,tricycles,andvehiclesintendedprimarilyforoff-highwayuse.Thislimitationislargelyarecognitionofthetypesofvehicleshistoricallymeasuredforrideanddirectionalcontrolsimulation,sinceSAEJ1574-1hasbeenwrittentodocumentthecurrentstate-of-the-artratherthantoexpandit.Additionally,inclusionoftheseothervehiclesmightwellrequiremeasurementofotherchassischaracteristicstoproperlysimulatetheirdynamiccharacteristics.Themeasurementoftheseadditionalcharacteristicsmaynotbesupportedbywidespreadexperimentalpractice.1.1AssumptionsandLimitations—ThefocusofSAEJ1574-1isconsolidationanddocumentionofthebestexistingtechnology.Theintentistoavoidintroducingunprovenandunestablishedpractices.Theassumptionsrelatedtothemethodsofsuspensioncharacteriza