大学毕业设计（外文翻译）Electro-hydraulicproportionalcontroloftwin-cylinderhydraulicelevatorsAbstractThelargesizeofthecabofanelectro-hydraulicelevatornecessitatesthearrangementoftwocylinderslocatedsymmetricallyonbothsidesofthecab.Thispaperreportsthedesignofanelectrohydraulicsystemwhichconsistsofthreeflow-controlproportionalvalves.Speedregulationofthecabandsynchronizationcontrolofthetwocylindersarealsopresented.Apseudo-derivativefeedback(PDF)controllerisappliedtoobtainavelocitypatternofthecabthatprovestobeclosetothegivenone.Thenon-synchronouserrorofthetwocylindersiskeptwithin±2mmwithaconstrainedstepproportional-derivative(PD)controller.Asolenoidactuatednon-returnvalve,i.e.ahydrauliclock,isalsodevelopedtopreventcabsinkingandalloweasyinverse-fluidflow.Keywords:Hydraulicelevator;Velocitytracking;Synchronization;Hydrauliclock1.IntroductionThemodernhydraulicelevatoriscurrentlyanexcellentandlow-costsolutiontotheproblemofverticaltransportationinlowormid-risebuildings,andinthoseapplicationsrequiringverylargecapacities,slowspeedsandshorttraveldistances.Theseincludescenicelevatorsinsuperstoresorhistoricalbuildings,stageelevators,shipelevatorsandelevatorsforthedisabled,etc.Inmostcases,hydraulicelevatorscanbeadaptedtoarchitecturaldesignrequirementswithoutcompromisingenergysavingandefficiencyrequirements.Inaddition,theuseoffire-resistantfluidmakesthehydraulicelevatorasuitablechoicewhenelevatorshavetooperatenearhazardssuchasfurnacesoropenfires.Hydraulicdrivesareusedpreferablyinelevatorswherelargepayloadsneedtobecarried,suchasforcarelevatorsormarineelevators.Inheavyloadcases,anelevatorcabusuallyhasdirectlyactingorside-actinghydrauliccylinders.Thedirect-actingarrangementinvolvesadeeppit,substantialriskofcorrosionofthe大学毕业设计（外文翻译）buriedcylindersandthedifficultyofreplacingfailedcylinderparts.Thus,inmanysituationstheside-actinghydrauliccylinderispreferred,despitethefactthatitprobablyincreasesrailwearduetoinsufficientcabstiffness.Intheextremeconditions,i.e.whenlargecabsizesandunevenpayloadsareinvolved,thecab'sflexibilitymayevencausetheguideshoestosticktotherails,whichisverydangerous.Therefore,insuchcases,afeasiblesolutionistoarrangetwodirectlyactingcylinderssymmetricallyoneachsideofthecab,asshowninFig.1.Itshouldbenotedthatsmoothrunningcannotbeignoredbecausepeoplemaybepartofthepayloadsthataccompanythefreight.Themajorissuewhendesigningacontrolsystemistoensurethesynchronousmotionofthetwocylinders.Theerrorduetothenon-synchronousmotionofthetwocylinderscaused,byanunevenloadunderequalpressure-control,whichisgenerallyusedforelevatorcontrolwithmultiplehydrauliccylinders,isschematicallyshowninFig.2.ItisobviousfromFig.2thatequalpressure-controlisnotsuitableforasynchronizedhydraulicelevator.Whenthepayloadislocatedontherightsideofthecab,theleftcylinder,withalighterload,willmoveupwardfasterthantherightone.Thespeeddisparitybetweenthetwocylinderswillnotceaseuntilthereactionforcesactuatedbytherailsonboththelowerleftandupperrightguideshoesattachedonthecabarebalancedbythehydraulicforcedifference.Thenon-synchronisationofthetwocylinderscanonlybereducedbyflowcontrol,i.e.byensuringthatthefluidflowsintothetwocylindersperunittimearethesame.大学毕业设计（外文翻译）Thispaperpresentsanelectro-hydraulicsystemforthecontrolofanelevatorwithtwincylindersthatarelocatedoneachsideoftheelevatorcab.Thedesignedsyste...
