外文翻译控制移动液压起重机.docx

外文翻译控制移动液压起重机.docx

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外文翻译控制移动液压起重机

翻译部分

英文原文

CONTROLOFMOBILE

HYDRAULICCRANES

MarcE.

MÜNZER

AalborgUniversity

InstituteofEnergyTechnology,

Pontoppidanstræde101

DK-9220Aalborg,Denmark

Thegoalofthethesisdescribedinthispaperistoimprovethecontrolofmobilehydrauliccranes.Thethesisissplitintofiveparts:

arequirementsanalysis,ananalysisofthecurrentsystemsandtheirproblems,ananalysisofdifferentpossibilitiesforsystemtopologies,developmentofanewcontrolsystemforthenearfuturebasedonelectro-hydraulicseparatemeterin/separatemeteroutvalves,andfinallyananalysisofmoreadvancedandcomplexsolutionswhichcanbeappliedinthemoredistantfuture.Theworkofthethesiswillbedoneincoop-erationwithindustrysothethesiswillhavemoreofanindustrialfocusthanapurelytheoreticalfocus.

Keywords:

MobileHydraulicCranes,ControlStrategies,SeparateMeter-in/SeparateMeter-out.

1INTRODUCTION

Thegoalofthethesisdescribedinthispaperistoimprovethecontrolofmobilehydrauliccranes.Amobilehydrauliccranecanbethoughtofasalargeflexiblemechanicalstructurewhichismovedbysomesortofcontrolsystem.Thecontrolsystemtakesitsinputfromahumanoperatorandtranslatesthiscommandintothemotionofactuatorswhichmovethemechanicalstructure.

Thedefinitionofthiscontrolsystemispurposelyleftvagueinordernottoimposeanycon-straintsonitsdesign.Thecontrolsystemconsistsofactuatorswhichmovethemechanicalstructure,ameansofcontrollingtheactuators,ameansofsupplyingpowertotheactuators,andawayofacceptinginputsfromtheoperator.Itisthiscontrolsystemwhichisthetargetofthisthesis.Thegoalistoanalyzetherequirementsmadeonthecontrolsystemandpresentguidelinesforthedesignofnewcontrolsystems.

Thethesiswillbesplitintofiveparts:

1.Analysisoftherequirementsofthecontrolsystem,fromtheperspectiveoftheopera-tor,themechanicalsystem,efficiency,stability,andsafetyrequirements.

2.Analysisofcurrentcontrolsystemsandwhattheirproblemsare.

3.Analysisofthedifferentoptionsforthecontrolsystem:

differenttypesofactuators,differenttypesofcontrolstrategies,anddifferentwaysoforganizingcomponents.

4.Presentationofanewtypeofcontrolsystem,whichiscommerciallyimplementable.Asystemthatwillmeettheneedsofindustryinthenearfuture.

5.Analysisofmoreoptimizedsystems,withhigherperformance,betterefficiency,moreflexiblecontrol,etc.Thiswillbelesscommerciallyapplicablebutwillbeastartingpointformoreresearch.

2SECTIONSOFTHETHESIS

2.1RequirementsAnalysisoftheControlSystemBeforestartingdetailedworkondevelopingnewcontrolsystems,itisimportanttoanalyzewhattheexactdemandsareonthecontrolsystem.Thecontrolsystemisinfluencedbymanyfactors.Forexample:

themechanicalstructureitiscontrolling,thehumanoperator,effi-ciency,stability,andindustryregulations.

Industryregulationsarethefirstrequirementsthathavetobeaddressed.Thingslikehoseruptureprotectionandrunawayloadprotectionmakealotofdemandsonthecontrolsystem.Afterregulations,stabilityisthenextmostimportantrequirement;withoutstabilitythecon-trolsystemcan’tbeused.Oncestabilityhasbeenassured,theperformancerequirementsofthecontrolsystemhavetobeset.Theyaredeterminedbythemechanicalstructureofthecraneandthehumanoperator.Themechanicalstructureofamobilehydrauliccraneisaverylargeflexiblestructurewhichhasverylownaturalfrequencies.Topreventoscillationsitisnecessarytokeepthespeedofthecontrolsystembelowthisnaturalfrequencyortodevelopacontrolsystemwhichcanincreasethisfrequency.Thehumanoperatoralsoimposeslimitsonthecontrolsystem.Ifthecontrolsystemistooslowortoofastthenitisimpossibleforahumanoperatortogiveitproperinputs.Andfinally,oncetheregulationshavebeenmet,sta-bilityisassured,andtheperformanceisattherightlevel,thepowerefficiencyofthecontrolsystemhastobeoptimized.

2.2AnalysisofCurrentControlSystems

Beforedesigninganewcontrolsystemitisgoodtoanalyzethecurrentcontrolsystemstofindoutwhattheirproblemsare.Currentcontrolsystemsaremainlyhydraulicandcansufferfromthreemainproblems:

1.Instability

2.Highcost

3.Inefficiency

2.2.1Instability

Instabilityisaseriousproblemasitcancauseinjurytohumanoperatorsordamagetoequip-ment.Whenasystembecomesunstableitusuallystartstooscillateviolently.Toavoidinsta-bilityincurrentsystems,thedesignerseithersacrificecertainfunctionswhicharedesirable,oraddcomplexityandcost.Forexample,inthecraneshowninFigure1,itwouldbedesir-abletohavecontroloverthespeed.Butduetothesafetysystemthatcranesarerequiredtohave,standardspeedcontrolisnotstable.Toaddspeedcontrolrequiresamorecomplexandmoreexpensivemechanicalsystem.

Theparametersofahydraulicsystem,suchastemperatureorloadforce,alsoaffectstability.Asystemthatisstablewithonesetofparametersmightbeunstablewithanotherset.Toensurestabilityovertheentireoperatingrangeofthesystem,performancemustsometimesbesacrificedatoneendoftheparameterrange.

2.2.2Highcost

Currentsystemsarepurelyhydraulic-mechanical,soiftheuserwantsacertainfunction,theuserbuysacertainhydraulic-mechanicalcomponent.Becausemostusershavedifferentrequirements,therearemanydifferentvariationsofthesamebasiccomponent.Thismeansthatmanyspecializedcomponentsmustbemanufacturedratherthanonestandardproduct.Thisdrivesupthecostofcomponents.

2.2.3Inefficiency

Oneformofinefficiencyincurrentsystemsisduetothelinkbetweentheflowsofthetwoportsofthecylinder.Thisisbecausemostvalvesuseasinglespooltocontroltheflowinbothports.Becauseofthislink,itisimpossibletosetthepressurelevelsinthetwosidesofthecylinderindependently.Therefore,theoutletsidewilldevelopabackpressurewhichactsinoppositiontothedirectionoftravel,whichincreasesthepressurerequiredontheinletsidetomaintainmotion.Sincetheforcegeneratedbytheactuatorisproportionaltothepressuredif-ferencebetweenthetwosides,theactualpressuresinthecylinderdon'taffecttheactionofthecylinder.Forexample,theactionofthecylinderfor0psi/600psiwouldbethesameas1000psi/1600psi.However,inthesecondcase,thepowersupplywouldhavetosupplymuchmorepower.Thisextrapoweriswasted.

2.3DifferentOptionsforControlSystems

Currentcontrolsystemsusehydraulicactuatorswithdirectional/proportionalvalvestocontrolthemovement.Howevertherearemanydifferentoptionsforcontrollingacylinder.Optionsrangefromnewhighperformanceelectro-hydraulicvalves,toseparatemeterin/separatemeterout（SMISMO）valves,tohydraulicbussystems,tointelligentactuatorswithbuiltinpowersupplies,topumpbasedcontrolstrategies.Thesesystemsallhaveadvantagesanddis-advantageswhichneedtobeanalyzedifthemostoptimumsolutionistobechosen.

2.4NearFutureSolution

Itisexpectedthatevenifitisproventhatacompletelynewsystemtopologyistheoptimumconfiguration,thecranemanufacturersandcomponentmanufacturerswillnotacceptthenewtechnologyovernight.Thiswillmostlikelytaketime,soaninterimsolutionwillbedevel-oped.

ThissolutionwillbemadeupofmicrocomputercontrolledSeparateMeterIn/SeparateMeterOut（SMISMO）valves（Elfving,Palmberg1997;Jansson,Palmberg,1990;

Mattila,Virvalo1997）.SMISMOvalveswillmakeitpossibletoimplementnewcontrolstrategieswhicharemoreefficientandstable.Themicrocomputerwillmakeitpossibletointroduceflexibilitytovalves.Variantscanbeprogrammedinsoftware.Thiseliminatestheneedtomanufacturehundredsofdifferentvariants.Thecranemanufacturerwillbeabletochoosetheexactfunctionshewantsinhisvalve,whilethecomponentmanufacturerwillhavetomanu-factureonlyonevalve.Thiswilllowerthecost,eventhoughtheperformancewillhaveincreased.

2.5AnalysisofHigherPerformanceSolutions

Thisanalysiswilldependontheresultsoftheanalysisofdifferenttopologies.Ifitisshownthatpumpbasedcontrolistobethewayofthefutureforexample,thenanalysiswillbeper-formedinthisarea.Anotherareawhichwillalsobeexplored,istoolpositioncontrol.

3LABORATORYFACILITIES

Asthefocusofthisthesisisondevelopingcontrolstrategiesthatcanbeimplementedoncommercialmachinery,muchemphasiswillbeplacedonexperimentalresults.Experimentalresultswillbeobtainedfromtwosystems.Thefirst,asimpleonedegreeoffreedomcrane,wasdesignedasanexperimentalplatform.ThesecondisarealcranewhichwasdonatedtotheUniversitybyHøjbjergMaskinfabrik（HMF）aDanishcranemanufacturer.RefertoFigure1.

Figure1ExperimentalSystemsinLaboratory.

Left:

OneDOFcranemodel.Right:

RealMobileHydraulicCrane

Astherearecurrentlynocommerciallyavailableseparatemeter-in/separatemeter-outvalves,twoseparatevalveswillbeusedinstead.AsamplecircuitofonecylinderisshowninFigure

2.Thecontrolalgorithmswhichcontrolthevalves,willbeprogrammedonaDigitalSignalProcessor（DSP）/Pentiumdualprocessorsystem.TheDSPwillrunthecontrolcodeandthePentiumwilldodiagnosticsandprovideagraphicaluserinterface.

Figure2SeparateMeterIn/SeparateMeterOutSetup

4CURRENTWORK

4.1FlowControlbyDirectActuationoftheSpool

Mostflowcontrolvalvesonthemarkettodayworkwithapressurecompensator（Andersen;Ayres1997）.Thepressur