简介：Lowweightandcompactnessarethemainrequirementsoncomponentsforexoskeletons.Fordrivesthismeansalsohighefficiencytokeepenergystorageandpowertransducingdevicessmall.Thedigitalhydrauliccylinderdriveisanexcellentcandidatetobecomeasuperiortechnologyforexoskeletonactuation.Itrequiresseveralvalvestocontrolpressureinitsmanychambers.Solenoidvalvessufferfromthehighweightandspaceofthesolenoids.Inthispaper,thehydraulicbinarycounterinaconfigurationwithonlypassiveelementsisstudiedmathematically,sinceitcancontroladigitalcylinderwithmuchsmallerspaceandweightthanmagneticallyactuatedvalves.Fromqualitativeconsiderationsofthesystemequationssupplementedbyanumericalstudy,itisshownthatsuchacounterworksproperly.Butitposesrequirementsonthecontrolpressurerangewhicharedifficulttofulfilfordigitalcylinderdriveswithmorethanfivechambers.

简介：Remainingusefullife(RUL)estimationisatopicthathasgainedmoreandmoreattentioninthefieldoffluidpowersystems,thankstothetremendouspotentialsshownforimprovingsafetyandreducedproductionlosses.However,manychallengesrelatedtoRULestimationarenotsolvedyet,mainlyconnectedtothedefinitionofthehealthstatusofeachcomponent.Aprognosticmethodbasedonadata-drivenmethodologyforhydraulicsystemsishereproposedtoestimatethepercentageoflifealreadyspentbythemonitoredcomponents.Thepotentialsofthemethodologyareshownconsideringthecaseofatruck-mountedhydrauliccrane,forwhichasimulationmodelwasavailable.

简介：Thispaperpresentsananalysisofthepotentialforenginespeedreductioninhydraulicequipment,takingintoaccountnotonlytheminimumenginespeedrequiredtomeetthecurrentflowdemand,butalsotheminimumspeedcapableofacceleratingtheenginetomeetincreasedflowdemandinthenearfuture.Thisisapredictivetask,asitrequiresanestimateoftheoperator'sintentiontoincreaseflowdemand.Wepresentananalysisofthepotentialforenginespeedreductionusingaworkcyclefroma40tonexcavatorloadingatruck,whichresultsinapotential33%reductioninthemeanenginespeedwithnoreductioninusefulworkrate.Wealsopresenttwonewenginespeedcontrolalgorithmstoperformthispredictivetask.

简介：Tortuosityisoneofthekeyparameterstocharacterizethetransportpropertiesofporousmedia.Therearemanymodelsfortortuosityestimationbasedonsomedefinitions:geometric,hydraulic,electric,anddiffusivedefinitions.However,relationshipsamongthosetortuositiesremainunclearduetothelackofdirectcomparisononthesameporousmedia.HerewefocusonhydraulicandelectrictortuositiesandhaveconductedaseriesoffiniteelementsimulationswiththeNavier–Stokesequationandtheequationforelectriccurrenttodirectlycomparetortuosities.Theresultsrevealedthat:(1)onaverage,hydraulictortuosityis15%greaterthanthatoftheelectricone;(2)theproposedmodelbasedonthevanGenuchten-typefunctionsuccessfullyapproximatesbothhydraulicandelectrictortuosities;(3)tortuositiesobtainedfromtheporousmediapackedwithcircularparticlesandsquareparticlesshowquantitativelysimilartrends.

简介：Hardwareintheloopsimulation(HILS)hasbeeninvestigatedinthefieldofthemultibodydynamics(MBD),whichcombinedtheMBDsimulationwiththeactualmechanicalsystem.ThefastsimulationisnecessaryfortheHILSsysteminordertorequiretherealtimesimulation.Thispaperpresentsafastsimulationtechniqueusingthedomaindecompositionmethodwiththeiterationintheflexiblemultibodysysteminwhichflexiblelinkagesystemandelectro-hydraulicdrivesystemarecoupledwitheachother.

简介：Electro-hydraulicservovalveisatypicalcomplicatedmulti-domainsystemconstitutedbymechanical,electric,hydraulicandmagneticcomponents,whichiswidelyusedinelectro-hydraulicservosystemssuchasconstructionmachinery,heavyequipment,weaponandsoforth.Thetraditionalmethodofmodelingandsimulationofservovalveisbasedonblockdiagramorsignalflow,whichcannotdescribetheservovalvesystemfromcomponentslevelnorbeusedinmodelingandsimulationofoverallservosystems.Intheprocedureoftraditionalmethod,computationalcausalitymustbeinvolvedinmodelingofservovalve,whichisinconvenienttoexecutemodificationoncomponentsorparameters.Modelicaisanobject-orientedmodelinglanguagewhichissuitedforlarge,complex,heterogeneousandmulti-domainsystems.ThekeyfeaturesofModelicaaremulti-domain,object-orientedandnon-causal,whicharesuitableformodelingofservovalveandmakethemodelreadable,reusable,andeasytomodify.Thesimulationresultsshowsimilarcurveswithtraditionalmethod.Thisnewservovalvemodelingandsimulationmethodcanprovidetheengineersamoreefficientwaytodesignandoptimizeaservovalveandanoverallservosystem.