Multi-DomainSimulation:MechanicsandHydraulicsHHHofanExcavatorHirokazuAraya,MasyukiKagoShimaMechanilEngineeringRerchLbortoryKobestl,Ltd,Nishi-KvobeHyogo6512271,JapanAbstracItidemonstraedhowtomodelandsimulatenexcavatorwithModelicandDymolabyusingModelicalibrriesformti-bodyndfhydraulicsystem.Thehydrulicsystemisontrolldbya“loadsensing”controlle.Uualy,modelscontaining3-dimnsionalmechanilndhydrauliomponentsaredificultosimulte.AthandofthexcavatoritshownthaModelicawluitdorsuchkindsofsystemsimulations.1.IntroducionThedesignofanewproductrequirsanumberofdecisonsintheinitalphasethaseverlyafecthesuccesofthefinihedmchine.Today,digitlsimultionistheforusdinarlytagetolookatdiferntoncepts.heviewofthipaperithaanewexcvatoristbedesignedndsveralcndidatshydraulicontolsystemhavetobeeluated.Stmstconsistof3-dimnsionalmechanialndofhydraulicomponentslikeexcavatorsareficultosimulat.Usualy,twodiferntsimulationnvironmnthavetobeoupled.Thiiofteninconvenient,ladstounnecesrynumeicalproblemsandhasfragilinterfacs.IthisarticlitsdemonstrdathandofthemodelofnxcvatortModeliweluitedfortheetypesofystems.T3-dimensionalcomponentsofthexcavatorarmodeldwithhenew,freModelicaultiBodylibrary.Thialowsepecilytouseannalyticsolutionofthekinemtiloopathebucketndtokethemasofthehydruliylinder,i.e.,t“forcelmnts”,directlyintacount.Thydraulicpartismodeledinadetiledway,utilzngpump,valvesndylindersfomHyLib,ahydraulicslibrryforModelica.Forthecontrolpartageneic“loadsensing”controlystemisused,mledbysetofsimplequations.Thisapprchgivestheequirdultandkeepstheimenededforanalyzingtheproblemonaresonablelvel.2.ModlingChoicesThereasveralpproacheswnsimulatingasystem.Dependingonthetaskitmaybenecytobuildaveryprecimodel,continingverydetailoftystemndedingalotofinformtion,.g.,mlparametrs.Thiskindmodelsiexpensivetobuildupbutontheotrhandveryusfulipaametrofaweldefinedsystmhatbemodified.Atypicalexamplistheoptimztionparmtrsofacounterbalancevalveinaxcvator(Krft1996).Theotrkindofmodelisneededairstudyofasystem.Inthiscaesompropertiesofthepump,cylinderandloadsepecifed.Rquirdinformtionabouttheperformanceofthasystem,.g.,thesdofthepistonsorthenecesaryinputpowethepumpsft,omakeadecionwtrthideigncanbeusdinprincplfortaskthand.Thismodelhastherefortobe“chep”,i.e.,itmbepossibletobuilditnahortimeithoutdetaildknowledgeofparticularcomponents.Theauthorintendedtobuildupamodelofthesecondtype,runitandhavefirstresultwithminimumamountoftimespent.ToahivethisgoalthemodelinglanguageModelica(odelic2002),theModelicsimultionenvironmentDymola(Dymol2003),thenewMlicalibrryfor3-dimensionalmchanialsystem“ultiBody”(Otertal.2003)ndtheodelicalibrryofhydrulicomponentHyLib(eatr2000)sused.Tmodelonsistofthe3-dimensionalmehanicalconstructionoftheexcavator,adetileddecriptontpowrhydraulisndgeneic“loadsnsing”controlle.ThismodelwilbeavailbleasdemointhenextversionofHyLib.3.CtrucionofExcavatorsInashematidrawingofatypicalexcavatorunderconsiderationishown.Itconsitofchaintrckndthehydrulipropeldrivewhihisusedtomanoeuvrethemahinebutusualynotduringaworkcycle.Ontopofthaiacrigewhertopertoristing.Itcanrotteroundvertialxisithrespetothehaintack.ItalsoholdstheDieslngine,thehydraulicpumpsndcontolystem.Furthermore,thereiaboom,anrmandtendbucketwhihisatchedviaplanarkinematiclooptohearm.Boom,armndbucketcanberotatedbytheappropriatecylinders.Figureshowthatherequirdpresurinthecylindersdependonthepositon.orthe“trecd”situaiontheeitboomcylinderis60%higherthanittapositon.Notonlythepositonbutalsothemovementhavetobetakeintocount.Figure3showasituaiwheretrmhangsdown.Ifthecrigedoesnotrotateheriapullingforcerquidinthecylinder.Whenrotatingexcavatorcntypiclyottewithupto12volutionsperminutetforceinthermylinderhangesitignandnowapushingforceisneded.Thishangeisveysignificantbecausenowthe“ctive”chamberoftheylinderswitcheandtmustbetkenioountbytontrolsystem.Bothfiguresdemonstaethasimulationmodelmustakeintoacountthecouplingsbetwnthefourgrsoffredomthisexcavatorhas.Asimplermodelthausesaconstantloadoreachcylindeandthewiveldrileadstooneousresult4.LoadSensigSystemExcavatorhavetypicalyoneDieslngine,twohydraulicmotorsandthrecylinders.Therexistdifernthydraulicruitsprovidetheonsumerwithherequidhydraulicnergy.AtypicldesigniaLoadSensingciruithatisenergyficntnduserfindly.Theiaitohaveflowratcontolsystemforthepumpsuchthaitdelivesxactlyneededflowrate.Asensortheprurdropacrossanorifceisused.Therefncvalueistheitancoftorifce.Ashemtidrwingihownigur4,agoodintroductiontohatopiisgiveni(anon.1992).Thepumpcontrolvalvemaintnsapresurathepumpporthatistypicaly15barhigherthanthepresurintheLSline(=LoadSensingline).Ifthediretionalvalveisclosedtpumphatreforastnd-byprsurof15bar.itsopenthepumpdeliversaflowratetladstopreurdropracossthadirectionalvalve.Note:Thedictionalvaveisnotusdtohrottlehepumpflowbutasflowmetr(prsurdropthaisfedback)andsarfnc(rsitance).Theciruitisnegyeficntbecausethepumpdeliveronlytheneededflowrt,throttlinglossarsmlompardtootrciuits.Ifmorethanonecylinderisusedtheciruitbecomesmorecompliated,sefigure5.E.g.iftheboomrequiaprurof100barandthebucketprsurof300barthepumppresurmustbebove300barwhichouldcausenunwantedmovementoftboomcylinder.Thereforcompensatorsareusthathrottlheoilfowandthusachieveapresurdropof15barcostheparticulardiectionalvalve.Thesecompenstorscnbeinstaledupsteamordownstemofthertill.Anadditionalvavereducsthenominalprsuredifrntialftmaximumpumpflowrteorthemaximumprureisrached(.g.Nikolus1994).5.ModlofechanialPartInFigur6,aModelicashematicofthemechanialpartishown.Thechaintrackisnotmodeled,i.e.,itumedthatintrckdoenotmove.Components“rev1”,.,“rv4”arethe4rvolutjointstomovethepartselativetoeachother.Theiconswithhelongblacklineare“virtual”rodsthaausdtmrkspeifcpointsonapart,especilythemountingpointsofthehydrulicylinde.Thelightbluepheres(b2,b3,b4,b5)arebodiesthavemasndaninertiaensorandreusedtomodelthecorrespondingpropertioftheexcvatorparts.Thethreomponent“cyl1f”,“cyl2f”,and“cyl3f”arelineforceomponentsthadescribeaforcierationalongalinebetwentotchmntpoints.Themalgrenquaresthescomponentsreprsnt1-dimnsionaltransltionalconnetorsfromtheModelica.Mehani.Tanslt