Recent developments in passive interconnected vehi

REVIEWARTICLEWadeA.SMITH,NongZHANGRecentdevelopmentsinpassiveinterconnectedvehiclesuspension©HigherEducationPressandSpringer-Verlag2009AbstractThispaperpresentsanoverallreviewonthehistoricalconceptdevelopmentandresearchadvancementofpassivehydraulicallyinterconnectedsuspension(HIS)systems.ItstartswithanintroductiontopassiveHISsystemsandtheirvariousincarnationsdevelopedovermanydecades.Next,adescriptionisprovidedofarecentlyproposedmultidisciplinaryapproachforthefrequency-domainanalysisofvehiclesfittedwithanHIS.Theexperimentalvalidationandapplicationsofthemethodtobothfreeandforcedvibrationanalysisarediscussedbasedonasimplified,roll-planehalf-carmodel.Afinite-element-method-basedapproddachformodellingthetransientdynamicsofanHISvehicleisalsobrieflyoutlined.Inaddition,recentworkontheinvestigationofNVHassociatedwithHIS-equippedvehiclesismentioned.DiscussionisthenprovidedonfutureworktothefurtherunderstandingofHISanditsapplications.Thepaperconcludesthatinterconnectedsuspensionschemescanprovidemuchgreaterflexibilitytoindependentlyspecifymodalstiffnessanddampingparameters–acharacteristicuniqueamongpassivesuspensions.Itpointsoutthatthereisaneedforsystemoptimisation,andtherearetrouble-someNVHissuesthatrequiresolutions.ItsuggeststhatfurtherresearchattentionandeffortbepaidtoNVHissuesandsystemleveloptimisationtogainagreaterunder-standingofHISandtobroadenitsapplications.Keywordsinterconnectedsuspensions,rolloverpreven-tion,vehicledynamics,ridecomfort,multibodysystemdynamics,hydraulicsystemdynamics1IntroductionFatalcrashesduetovehiclerollovershavebeenfrequentlyreportedinrecentyearsaroundtheworld.Sportsutilityvehicles(SUVs),typicallyhavinghighermasscentres,areparticularlyvulnerabletothistypeofaccident[1].Theeventsleadingtovehiclerolloversarecomplex,withmanyfactorsinfluencingthevehiclemotion.Althoughsomeofthesefactors–e.g.,roadroughness,unexpectedbadconditions,andhumanerrorsmadeinsteeringinput–areunpredictable,itiscommonlyagreedamongautomotiveengineersthatavehiclecouldbedesignedtominimisethechancesofrolloveroccurring.Apartfromtheimplementa-tionofantilockbrakingsystem(ABS)andelectronicstabilityprogram(ESP)technologiestoimprovevehicles’safety,itisclearthatadvancedsuspensionsystemsplayakeyroleinreducingvehicularrolloverpropensity.Thissectionintendstoprovidethereaderwiththebackgroundinformationnecessarytocontextualisetheworkpresentedinsubsequentsections.Tothisend,itbeginswithabriefbackgroundonvehiclesuspensionsingeneralandadetailedreviewofpastworkoninter-connectedsuspensionsinparticular.Thisisfollowedbyanintroductiontothehydraulicallyinterconnected(‘kinetic’)suspensionsystemsdevelopedbyTenneco1).1.1Background-structureandroleofvehiclesuspensionsystemsAutomotivesuspensionsystemsprovideaconnectionbetweenthevehicle’sroadwheelsandthevehiclebody.Intheirmostbasicform,modernsuspensionsystemsconsistofacombinationofrestoringanddampingmedia.Thisistypicallyrealisedintheformofsprings,whichactagainstanyrelativedisplacementbetweenthevehiclebodyandroadwheelsfromsomeneutralposition,andshockabsorbers,whichprovideenergydissipationthatisgenerallyafunctionoftherelativevelocitybetweenthevehiclebodyandtheroadwheels.ReceivedOctober9,2009;acceptedOctober19,2009WadeA.SMITH,NongZHANG(✉)MechatronicsandIntelligentSystems,FacultyofEngineering,Uni-versityofTechnology,Sydney,P.O.Box123,Broadway,NSW2007,AustraliaE-mail:[e-mail]1)TennecoInc.CompanyWebsite–ProductsandTechnologies.TennecoInc,[Online]Available:[Accessed:2September,2009].Front.Mech.Eng.ChinaDOI10.1007/s11465-009-0092-zManyexpectationsareplacedonmodernvehiclesuspensions.Gillespie[2]statesthatasuspensionsystem’sprimaryfunctionsareto:1)isolatethechassisfromroadroughnessandallowthewheelstofollowtheroad;2)maintainrequiredwheelorientationrelativetotheroad,suchassteerandcamberangles;3)transmittothevehicletheforcesandmomentsproducedbythetyresandresistchassisroll;and4)maintaintyre-roadcontactandminimisenormalloadvariations.Sharpetal.[3]gofurther,statingthat,inadditiontothetypicalperformancerequirementsforridecomfortandhandling,the“total[suspension]designprobleminvolvesconsiderationofcapitalcost,spacerequirements,compo-nentweight,energyconsumption,maintainability,relia-bilityandfailuremodes,noisetransmissionandgenerationandadvertisingpotential”,and“extremeeventperfor-manceproperties”.Thecomplexitiesinvolvedinachievingbalancebetweentheseobjectiveshaveledtoincreasinginvestmentinvehicledynamicsandsuspensionresearchinrecentdecades.Mostearlyvehicledynamicsstudies[4,5]focusedontheroleofsuspensionsystemsinprovidingadequaterideperformance,i.e.,theisolationofthevehiclebodyfromexcitationsources.Bythe1950s,withagrowingemphasisondynamicperformanceandsafety,handlingandstabilitybecamemajortopicsofinvestigation[6,7].Ingeneral,avehiclewitharelativelystiffsuspensionislikelytopossessgoodhandlingstabilitybutpoorridecomfort,andviceversa.Morerecently,researcheffortshavebeenfocusedonadvancedsuspensionsystems,withaviewtoovercomingthecompromisebetween