外文翻译--基于充气橡胶袋的一个灵活机械手的设计和可行性测试 英文版.pdf

InternationalJournalofMachineTools&ManufacEngineerinaccepted5Decembeinflationwasdesigned,analyzed,builtandtested.ParametricFEanalyseswereconductedtoinvestigatetheeffectsofprocessanddesignparameters,suchasrubbermaterial,pressure,initialjawdisplacementandfriction.BasedontheFEAresults,asimple,singlerubber-materialswhenevertheyarenotprocessed.Humanhandshavebeenthemostcommon,versatile,effectiveandthecostofgrippersmaybeashighas20%ofarobotscost,dependingontheapplicationandpartcomplexity1.Formanufacturingsystemswhereflexibilityisdesired,themanufacturingcompaniesarerequiredtomeetcontinu-ouslychangingdemandsintermsofproductvolume,mostgrippersweredesignedfordedicatedtasks,andcouldnotberevisedforothershape,sizeandweightconditions.Lateron,avarietyofflexiblegripperdesignswereARTICLEINPRESSsuggestedtoovercomesuchdrawbacks.Buttheirhighcostwasabarrierinadditiontomaintenanceissuesandlimitationstofewmaterialsandapplications.Despitesuch0890-6955/$-seefrontmatterr2005ElsevierLtd.Allrightsreserved.doi:10.1016/j.ijmachtools.2005.10.009C3Correspondingauthor.Tel.:+7347637119；fax:+6465147590.E-mailaddress:(M.Koc-).delicateformofmaterialhandling.But,forrepetitivecycles,heavyloadsandunderextremeenvironments,grippershadtobedevelopedtosubstituteforhumanhands.Inthe1960s,aftertheemergenceofmodernrobots,grippersreplacedhumanhandsonnumerousoccasions.Robot-grippersystemsarefoundtobeeffectiveforrepetitivematerialhandlingfunctionsinspiteoftheirinitialcapitalandongoingmaintenanceexpensesbecauseoftheirreliability,enduranceandproductivity.However,varietyandrapidresponse.flexibleandreconfigurablemanufacturingsystems(FMSandRMS)haveemergedasascienceandindustrialpracticetobringaboutsolutionsforunpredictableandfrequentlychangingmarketcondi-tions2.InordertofullyrealizethebenefitsofRMSandFMS,thegrippers,beingoneofthefewdirectcontactswiththeproductattheverybottomofthemanufacturingchain,mustalsobedesignedforflexibility.Intheearlydaysofrobotictechnologyapplications,understandingaboutthecapabilityandlimitationsofthegripper.Itwasfoundthatobjectswithdifferentshapes(cylindrical,prismaticandcomplex),weight(50g20kg.),andtypes(egg,steelhemi-spheres,waxcylinders,etc.)couldbepickedandplacedwithoutanylossofcontroloftheobject.Therangeofpositioningerrorfortwodifferentpartshapes(i.e.,prismaticorcylindrical)wasfoundtobe2090mm(translational)and0.030.91(rotational).r2005ElsevierLtd.Allrightsreserved.Keywords:Gripperdesign；Strategies；Flexible；Selection；Robotic；Rubber1.IntroductionAgripperisanend-of-armtoolingusedonrobotsforgrasping,holding,lifting,movingandcontrollingofcostofasuitablegrippermayevengohighersincetheyrequireadditionalcontrols,sensorsanddesignneedswithregardstobeingabletohandledifferentparts.Inthe21stcentury,undertheinfluencesofglobalization,pocketedflexiblegripperwasdesignedandbuilt.FeasibilityexperimentswereperformedtodemonstrateandobtainanoverallDesignandfeasibilitytestsofinflatablerubberHoChoi,MuammerNSFERConReconfigurableManufacturingSystems,CollegeofReceived30January2005；AvailableonlineAbstractInthispaper,wepresentfeasibilitytestresultsofaflexiblegrippercontrolstrategiesoftheexistinggrippers.Aflexiblegripperbasedture46(2006)13501361aflexiblegripperbasedonpocketsKoc-C3g,UniversityofMichigan,AnnArbor,MI48109,USA19October2005r2005designfollowingaliteraturesurveyonvarioustypes,designandontheuseofcompliantmaterials(i.e.,rubber)/locate/ijmactoolARTICLEINPRESSdrawbacks,costeffectiveflexiblegripperdesignshavebeenalwayssoughtasaviablesolutionforagilematerialhandlingsystemsasanimportantelementoftheenvisionedFMSandRMS.Forexample,assemblyoperationsinmanyindustriesmakeextensiveuseofdedicatedgrippersandfixtures.Thesearepart-specific,andtherefore,mustbemodifiedorreplacedwhenmodelchangesareintroduced.Thecostofredesigning,manufacturing,andinstallingthesegrippersandfixturesissubstantial(ontheorderof$100millionperplantperyearforautomotivemanufac-turers)andwouldbesignificantlyreducedifamoreflexiblealternativewasdeveloped.Inthispaper,followinganextensivereviewanddiscussionondifferentgrippertypesanddesignissuesinthefirstsection,aflexiblegripperdesignbasedontheuseofcompliantmaterialsandinternalpressure(i.e.,inflatablerubberpockets)approachisintroducedinthesecondpart.Thistypeofgrippersconformstotheshapeofanobjectbymeansofelasticgrippingelementsandpressurizationwithactivedegreesoffreedom.Inthethirdsection,theresultsofaparametricFEAstudyarepresentedtocharacterizetheperformanceoftheselectedconfigurationsoftheflexiblegripperunderdifferentloadingandpartconditionstodeterminetheproperparameterssettingandthematerial.Finally,inthefourthsection,followingtheprototyping,feasibilitytestsconductedtocharacterizethelimitsandcapabilitiesoftheflexiblegripperareexplained.2.Literaturesurveyongripperdesignandtypes2.1.DesignmethodologyofgrippersWrightetal.3comparedthegripperstothehumangraspingsystem,andcategorizedthedesignrequirementsofgrippersinto(a)compatibilitywiththerobotarmandcontroller,(b)securegraspingandholdingoftheobjects,and(c)accuratecompletionofthehandlingtask.Manyindustrialexamplesofgripperswerealsodescribed,andtheguidelinesforgripperdesignwerepresented.Phametal.1summarizedthestrategiesfordesignandselectionofgrippersindifferentapplicationcases.Intheirstudy,thevariablesaffectingtheselectionofagripperwerelistedas:(a)component,(b)task,(c)environment,(d)robotarmandcontrolconditions.Thecomponentvariablesincludegeometry,shape,size,weight,surfacequalityandtempera-tureofobjectstobehandled.Forreconfigurablesystems,theydividedthesecomponentsintopartfamiliesaccordingtotheirshapeandsize.Forthetaskvariables,typeofgripper,numberofdifferentparts,accuracy,andcyclewereconsideredinadditiontomajorhandlingoperationssuchaspick,hold,moveandplace.Fortherightgripperdesignattherightplace,allaspectsshouldbeconsidered,andmultiplevalidationtestsshouldbeconducted.Toreducethisexhaustiveeffort,Phametal.4developedanexpertsystemforselectingrobotgrippers.TheybuiltaH.Choi,M.Koc-/InternationalJournalofMachinehybridexpertsystemthatemploysbothrule-basedandobject-orientedprogrammingapproaches.2.2.GrippertypesandclassificationbydrivingforceGripperscouldbealsoclassifiedwithrespecttotheirpurpose,size,load,anddrivingforce.Typically,grippermechanismsandmajorfeaturesaredefinedbytheirdrivingforces.Thedrivingforcesforrobotgrippersareusuallyelectric,pneumatic,hydraulic；orinsomecases,vacuum,magneto-rheologicalfluidandshapememory,etc.Gripperswithelectricmotorshavebeenusedsince1960,abreastwithrobottechnology.Manyothergrippersadoptedmotordrivenmechanisms.Basically,thistypeofsystemsincludedstepmotors,ballscrews,encoders,sensorsandcontrollers.Asthearmsapproachtheobject,distance,force,weightandsliparedetectedbysensors.Atthesametime,acontrollerregulatestheforce,speed,positionandmotion.Friedrichetal.5developedsensorygrippingsystemforvariableproducts.Theyusedmultiplesensorstomeasurethegraspingforce,weightandslip.Masonetal.6andKerretal.7presentedthefundamentalsofgraspingwithmulti-fingeredhands.Leeetal.8comprehensivelyreviewedthefieldoftactilesensing.Forcontactandslip,Tremblayetal.9consideredslipdetection,andHowlegetal.10dividedslipintofourstages；pre-sliptension,slip-start,post-movement,andstoptobetteranalyzegraspingofparts.Anotherwayofactuatingtherobotgripperisthroughpneumatic(orhydraulic)systems.Pneumaticsystemshavebeendevelopedbecauseoftheirsimplicity,cleanlinessandcost-effectiveness.Warneckeetal.11andWrightetal.3developedasoftpneumaticgripperwhichcanhandlesoftmaterialssuchaseggs.Ottavianoetal.12developedgrasp-forcecontrolintwo-fingergripperswithpneumaticactuation.Theyproposedforcecontrolinatwo-fingergripperwithasensingsystemusingcommercialforcesensors.Asuitablemodelofthecontrolschemehasbeendesignedtocontrolthegraspingforce.Experimentsshowedthepracticalfeasibilityoftwo-fingergripperswithforcecontrolledpneumaticactuation12.Laneetal.13usedhydraulicforceforasub-searobothand.Theyofferednaturalpassivecompliancetocorrectforinevitablepositioninginaccuracywithsimpledesignandminimummovingparts.Thegripperfingerreliedontheelasticdeformationofcylindricalmetalbellowswiththincon-volutedwalls.Theconvolutionensuredthattheassemblywassignificantlystifferintheradialdirectionthanthelongitudinalone.Thereforelongitudinalextensionwasmuchgreaterthanradialexpansionwhensubjectedtointernalhydraulicpressure.Themodularfingertipcontainedavarietyofsensorsandinterfaces.Thefingertipcontactzonecontainsbothastraingageandapiezoelectricvibrationsensor.Closed-looppositioncontrolwasused.Itwasdrivenbyhydraulicpressuremeasuredfromsensorswithineachtube13.Grippersbasedonvacuumforcesaredesignedandusedmainlyfordeformableandlightweightparthandling.Tools&Manufacture46(2006)135013611351Kolluruetal.1417,forexample,usedsuction-basedcontrolforhandlinglimpmaterialwithoutdistortion,deformationordamage.Theydevelopedafixed-sizedgripperandalsoareconfigurablegrippersystemwithsuctionunits.Asensor-basedcontrolsystembasedonthehierarchicalcontrolarchitecturecontrolledtheoperationoftheroboticgrippersystem.Fixeddimensiongrippersweredevelopedforstackingdissimilar-sizedpanelsofclothes.Afuzzycontrollercomputestheneededsuctionandcontroldependingonmaterialporosity,weight,robotspeed,andtraveldistance.Rongetal.18presentedflexiblefixturesbasedontheuseofphase-changingmaterialsthatchangethephasefromliquidtosoliduponapplicationofelectricityorelectromagnetism(knownasmagneto-rheologicalMRfluid).Bertettoetal.19madeatwo-degreeoffreedompassiveclosureandactiveclosure.Passiveclosurewasdividedintopassiveformclosureandpassiveforceclosure.Theystudiedconditionsfortheseclosurestoholdanobjectsecurely21.Wallacketal.22developedanalgorithmforplanningplanargraspconfigurationforthemodularvise.Brownetal.23expandedthatworktoproducea3-Dfixtureandgripperdesigntool.Theydescribedseveralanalyses,andaddeda2-Dalgorithm,3-Dgraspqualityandgeometricloadinganalyses.Theyshowedsomeapplicationsandpotentialusesoftheircodeinanagileassemblyline23.Qianetal.24presentedanefficientalgorithmforcomputingobjectposesinamodularfixturegripper.Theyintroducedefficientalgorithmsforcom-putingposesofgivenobjects.ThecomputerprogramARTICLEINPRESSmovableH.Choi,M.Koc-/InternationalJournalofMachineTools&Manufacture46(2006)135013611352gripperactuatedbyshapememoryalloy(SMA)withaflexurehingeinmicroscale.TheydesignedNiTiSMAgripperandthetestshowedtobeabletoreachdesignperformance.TheSMAhassomedrawbackwhenitisappliedtohighworkingbandwidth,becauseofitsthermalresponse19.2.3.ControlalgorithmdevelopmentforgrippersAbasicroleofthegripperisgraspinganobjectsecurely.Forthispurpose,manyresearchershaveinvestigatedonconstrainingalgorithms.Asadaetal.20presentedformclosuregraspingbyareconfigurableuniversalgripper.Theyappliedtheformclosureconcepttograspingawork-piece.Theyanalyzedkinematicconditionsfortotallyconstraininganobjectwhichisassumedtobepiece-wisesmooth.Anefficientalgorithmforexaminingthetotalconstraintwasalsodevised.Thegripperhadreconfigurablefingersconsistingofamulti-degreeoffreedomlinkmechanism.Ithadthecapabilityofchangingtheconfig-urationofindividualfingerssothatthefingertipcouldbelocatedatanappropriatepositiondependingontheshapeofthework-piece20.Yoshikawaetal.21providedaunifiedtheoreticalframeworkforgraspingandmanipula-tionbyroboticgrippersandhandsaswellasforfixingworksbyfixturesandvises.TheyintroducedtheconceptofFig.1.Conceptualmodelsofflexiblegripperdesignswithrubberpockets,verticalrubberpockets,(b)hemisphericalrubberpockets,and(c)singlerubberplate.showeduniversalapplication,runningfastandaccurateresults24.Aftergripping,alignmentofapartforassemblyormachiningpurposeisneeded.Kanetoetal.25showedapracticalprocedureforachievinganenvelopinggrasp.Itconsistsofseveralphasesincludingapproach,lifting,graspingandcoordinatephases.Theexperimentalsoshowedtheeffectivenessoftheproposedgraspingproce-dure.Zhangetal.26showedanalignmentofpartsduringgraspingusingastandardparallel-jawgripper.Theyusedfourgripperpointcontactsthatwillalignthepartintheverticalplaneasthejawsclose.Thealgorithmforpartalignmentincludestoppling,accessibility,andform-closureanalysis26.Asmentionedinthegripperdesignsection,grippersshouldbecompatiblewiththerobotandcontroller.Thecontrolsystemcouldvaryaccordingtoitspurpose,constrainingalgorithm,environment,andcondition.Itcouldbeanindependentandsubordinatesystembasedonthepurpose.Thecontrolsystemcouldalsovarybasedonthesensorsandactuatorsthatareadopted.Forexample,Kolluruetal.15usedvisionandopticalsensorsforagrippersystem.Intheircase,thegrippingprocessiscomposedoftwosteps.First,thegripperiscoarselypositionedbymeansofavisionsensor.Second,finealignmentismeasuredandcontrolledusinganoptical/adjustablejawsandadditionalpinlocators,etc；(a)threerowsofpocketdesign.Inallcases,notethemultipleholesandpinsontheuppersensorarray.Foranintegratedroboticgrippersystem,theyalsosuggestedhierarchicalcontrolarchitectureandfuzzylogicformulation.Formanipulatingpayloadswithmultiplerobots,Sunetal.27describedanapproachtonon-modelbasedcontrolsofmulti-robotsystems.2.4.FlexiblegrippingstrategiesIntermsofaccomplishingflexiblegrippingtasks,fivedifferentstrategiesweresuggestedbyPhamandYeo1toachievetheflexibilityinacost-effectivemanner.Thefirstkindofgrippergainsitsflexibilityfromanumberofnotchesonthegrippingsurfacessothatobjectswithvariousshapescanbehandled.Obviously,notchingofgripperfingersisonlysuitableforthepartsofsimilarsizeandweight.Anotherflexiblegripperconceptisbasedoninterchangeablegripperfingers.Thismethodismoreflexibleandreliablethannotchingmethodwhenthegripperisequippedwithafingerchangingapparatusandastandardsetoffingers.Anotherstrategyistochangethegripperitself.Thismethodcanbeusedwhenasinglegrippercannothandleawholesetofpartswithdifferentsizes,geometriesandweights.Thesegrippersneed