外文翻译--仿生物脊柱的人形机器人Robota的设计 英文版.pdf

IEEE/RASEMBSInternationalConferenceonBiomedicalRoboticsandBiomechatronicsPisa,Italy,February2022,2006DesignofaBiomimeticSpinefortheHumanoidRobotRobota⁄LorenzoRoos,FlorentGuenter,AndreGuignardandAudeG.BillardAutonomousSystemsLaboratory3SchoolofEngineeringEPFLEcolePolyt´echniqueF´ed´eraledeLausanneStation9CH1015Lausannefflorent.guenter,aude.billardgepfl.chAbstractThispaperpresentsaprototypeof3degreesoffreedomarticulatedspineforthedollshapedhumanoidrobotRobota.Thisworkfollowsanapproachthatemphasizestheneedforahighhumanlikelinessinboththeexternalfeaturesoftherobotandinthekinematicsofitsmotionstoenhancehumanrobotinteractions.Thedesignofaspinalcordforourhumanoidrobotsatisfiesbothcriteriainprovidingofferingasmoothhumanlikeparallelmeansofbendingforwardandsideways.IndexTermsBiomimeticSpine,HumanoidTorsoI.INTRODUCTIONTheRobotaprojectdesignsaseriesofbiomimetichumanoidrobots12.Since1998,Robotahasbeingusedaspartofstudieswithautisticchildren3,4.Thesestudiescomparetheeffectthathumanlikefeaturesmayhaveontheinterestthatchildrenwithautismshowininteractingwithanotheragent.Thus,expressinghumanlikecharacteristics,bothintherobotsbodyfeaturesandintherobotsbehaviors,hasbeenforlongakeyconstraintinthedesignofRobota.ThecurrentprototypeofRobota,whichwedescribehereseeFigure1,willfindanapplicationinavarietyofworkonhumanrobotinteractions,conductedatourlaboratory,see,e.g.5,6.Inthese,westudythemeansbywhichonemayendowtherobotwithhumanlikemotionsthroughimitationlearning.Ahighresemblancebetweenthehumanbodyandthatofrobotsimplifieslargelythesocalledcorrespondenceproblem7,inwhichthemotionofthehumanmustbelettocorrespondtothatoftherobot.Sofar,ourworkhasconcentratedonteachingtherobotsimplemanipulatorymotionsinvolvingthetwoarms.ThedesignofaflexiblespinefortheRobotarobotwillallowustoextendthisworktoteachingmotionsinvolvingthewholetorso.Byrequiringthatthespineflexesthesamewayasthatofthehumanbodyalongthepanandtiltdirectionsofmotion,weensureagoodcorrespondencebetweenthehumanmotionsandthatoftherobotduringkinesthetic⁄ThisworkissupportedinpartbytheSwissNationalScienceFoundation,throughgrantno620066127oftheSNFProfessorshipsprogramandbytheEuropeanCommissionDivisionISTFutureandEmergingTechnologies,IntegratedProjectROBOTCUB.teachingsuchasthatdoneonourFujitsuHOAP2robot,seeFigure2.In8,wepresentedaprototypeofa7degreesoffreedomarmDOFandofa3DOFspairofeyesforanextendedversionofRobota.Inthispaper,wepresenttherecentdevelopmentofanarticulatedspinetoendowtherobotwithhumanlikemotionsofitstorso.Wereportonthevariousstagesofdesign,takingthetimetodescribesolutionsthat,althoughfeasibleintheory,appearedunpracticalwhenimplemented.Althoughthisisunusual,theliteraturetendingtoreportusuallyonfinalworkingprototypesonly,webelievethat,insomecases,itisalsoinstructivetoreportonunfeasiblesolutions,especiallywhenthosecanbeprovedwrongonlywhencreated.II.STATEOFTHEARTThedesignofhumanoidrobotsformagrowingbodyofroboticsresearch.However,thevastmajorityofthoseworksfollowarelativelyclassicalapproachinthedesignoftheactuatorsoftherobotstorso,bylocatingthoseseriallyatthelevelofthewaist.ExamplesofsuchrobotsincludeHondaASIMO9,SonyQRIO10,FujitsuHOAP12andHRP2P11developedbytheKawadaIndustries.AllofthesehaveeitheroneortwoDOFs,whereasthehumanoidrobotWABIAN12fromWasedauniversity,COG13atMITandARMAR14,ahumanoidrobotdevelopedattheKarlsruheuniversityhavethreeDOFs.Thereexists,however,afewsolutionsthatfollowmoreofabiomimeticdesign.Forinstance,theCLAandKENTA15,16robots,developedatTokyoUniversity,offertwosolutionsofarticulatedspine,thatmimicsthehumanspine.Forrecall,thehumanspineconsistsof24vertebraethatarestackedontopofeachother.Betweeneachvertebraisasoft,gellikecushioncalledadiskwhichplaytheroleofshockabsorberandkeepsthebonesfromrubbingagainsteachother.Eachvertebraisheldtotheothersbygroupsofligaments.Thespinalcolumnalsohasjointscalledfacetjoints.Thefacetjointslinkthevertebraetogetherandgivethemtheflexibilitytomoveagainsteachother.Theaveragerangeofmotionare§30–fortheflexionextension,§40–foradductionabductionand§30–fortherotation.Fig.1.CurrentprototypeofthenewRobota.Itencompassa6DOFsarmwith1DOFgripper,3DOFspairofeyesmountedwith2cameras,3DOFsneckand3DOFsspinalcord.Inalatterstage,theprototypewillbeembeddedinaplasticcoatingsimilartothatofcommercialdoll,,seeFigure3,toensurethatallmechanicalpartsarehidden.ThespineoftherobotKENTAisconstitutedof10jointswith3DOFsperjoint,soastomimictheassemblyofvertebraeinthehumanspine.40actuatorsareusedtocontrolthespineSee15.IntherobotCLA,thespineconsistsoffiveflexiblejoints,separatedbyarubberlayer.Therubbersendowthespinewithanaturalflexibilityandarepreconstraintinaway,suchthattheequilibriumpointliesinaverticalstraightposition.8cableswithactuatorsplaytheroleoftendonsbetweentheclavicleandpelvistomovetheentirespineSee15.Whilethesespinesareinmanywaysthebestexampleofsuchdesign,theyrequiretoomanyactuatorsandwouldnotfitthesmallbodyoftheRobotarobot.Thereexistalsootherhyperredundantrobots,albeitnothumanoids,suchastheroboticelephantstrunkoftheClemsonUniversity17orvarioussnakelikerobotsforexample18,19,whichofferinterestingsolutions.TheelephantstrunkoftheClemsonUniversityiscomposedofdiskslinkedtooneanotherby2DOFjoints.Thesedisksareusedtodrivethecablesystemwhichactuatesthetrunk.Betweentwodisks,therearefourpreconstraintspringstocreateanequilibriumpointwhenthentrunkisinastraightposition.Thesnakelikerobotscitedabovearedrivenbypneumaticpumps.TheSlimeRobot18isconstitutedofdisksactuatedbythreepneumaticactuatorbetweeneachofthem.TheOmniTreadrobot19iscomposedofdifferentsegments,eachofthemactionedbycaterpillars.Betweentwosegments,thereisapneumatic2DOFsjoint.Theserobotsofferinterestingsolution,especiallyintheiractuationsystem.However,theserobotshaveastructurewhichismeanttosupportalowloadhorizontally,and,thus,isnotoptimizedtoworkunderhighcompression,Fig.2.AdemonstratoristeachingamovementwhichrequiresbendingofthetorsotothehumanoidrobotHOAP2asitisthecaseforthespineofatwolegsstandinguphumanoidrobot.III.MECHANICALDESIGNTheRobotaprojectisconcernedwiththedesignandconstructionofaseriesofmultipledegreesoffreedomDOFdollshapedhumanoidrobots,whosephysicalfeaturesresemblethoseofahumanbaby.TheRobotaprojectispartofacurrenttrendofroboticsresearchthatemphasizestheneedfortherobottobearsomehumanlikenessbothinitsbodyfeaturesandinthekinematicsofitsmotionstoenhancehumanrobotinteractions,see,e.g.20,21,22,23.Asmentionedintheintroduction,theuseoftherobotRobotaaspartofstudieswithchildrenwithautism3setsanumberofconstraintsonitsdesign,includingthatitssizeremainsmall,itsweightlight,itscostlowandthatitsfeaturesremainaestheticandfamiliarsimilartothatofothertoysthechildrenwouldencounterintheirdailylife.InordertoensuretheoverallaestheticoftherobotRobota,wetookasreferencetheaveragesizeofa60cmtallcommercialdoll,seeFigure3andamaximalweightof4kg.TheseconstraintswereusedforallprecedentprototypesdesignedforRobotaThe7DOFsarm,the3DOFseyesandthe3DOFsneck8,24.Giventheexistingprototypes,thefollowingconstraintsweregivenforthedesignofthespine1Thespinemustbestrongenoughtosupportaloadof2Kglocatedat80mmupthelastvertebraeseeFig.12.2Thespinemustsmallenoughtofitinacylinderof210mmhighanddiameterof120mm.3Theweightmustnotexceed1.2kg.4Theactuationmustbedonebyamaximumofthreemotors,toremaincheapandeasilycontrollablebyanonboardcontrolleraPocketPC.5Thespinemustbeabletobendwithanangleof40–ineachdirection.Whilethereexistsafewprototypesofspinesforhumanoidrobots,see15,16andtheintroductionforareview,noneofthesesuitedtheconstraintslistedabove.ThespineoftheKENTArobotistoobigandhastoomanyactuators.ThesolutionusedforCLAismorerelevantFig.3.DollusedasreferenceforsettingthesizeofthenewrobotRobota.toourproblem.However,itstillhastoomanyactuatorsforourpurposeanditwouldnotbesuitabletocarrytheload2Kgoftherobotsheadandwouldleadtobucklingproblems.Ensuringthatallcomponentsremainsmalltofitwithinthedollsbodywhilesupportinganimportantloadinproportiontotheoverallsizeofeachlimbisandhasalwaysbeenatremendouschallengeinalltherealizationswehavedeveloped.A.ThefirstdesignTokeepthecontroloftherobotsimple,wedecidedtodecouplethethreeDOFsofthespine.TwoDOFsareusedtobendthespinefromfronttobackandfromlefttorightrespectively,seeFigure11.ThethirdDOFofthetorso,supportedbythespine,drivesthehorizontalrotationoftheshoulders.AclassicalsolutionisusedfortherotationofthethirdDOF.ThepointwastofindafeasiblesolutionforthetwofirstDOFs.Differentsolutionshavebeenexploredduringtheprojectusingdifferenttypesoftransmissionmeansforthemovement.1CablesystemThefirstdesignofthespineconsistedinastackofvertebraeseparatedbyrigidpolymerrings.TheringsintroducedaspacebetweenthevertebraeandlimitedthelateraldisplacementsseeFig4.Thevertebraewerefixedonetoanotherbyaspringpassingthroughtherings.Theshapeoftheringsallowedbendingbymaximum30–betweentwovertebrae.Therewasaflatpartbetweentheringsandthevertebraetoallowabetterstabilityintherestpositionstraightvertical.Holeweredrilledateachextremityofthecrossformedbythevertebraetofitthevariouscablesneededfortheelectronic.Thefirstproblemweencounteredwiththisdesignwasthatthelengthofthespinewouldchangewhenitbended,becausethecablesonbothsideswouldnotchangebythesamelengthwhenthetwocablesarefixedalongoneaxis,onewindsupwhentheotherwindsout.Thesecondproblemwasthat,ifwefixedthecablesonlytotheuppervertebrae,thespinewouldbendeachvertebraeseparatelyandoneaftertheotherone,startingwiththefirstone.Thus,Fig.4.ArubberdiskisplacedbetweeneachvertebraeandaspringisusedtofixonevertebraetoanotherFig.5.Thelinkbetweentwovertebraeisacardanjointandcompressionspringsareplacedoneachbranchtoinsurethestabilitythemovementwouldnothavebeensmoothlydistributedalongthespine.2CardanJointToaddressthefirstproblemmentionedaboveandinspiredbytheelephantstrunksolution17,wereplacedthepolymerringswithacardanjointwithcompressionspringsplacedoneachbranchofthecrossshapevertebraenearthecablesseeFig5.Thecardanjointsolvestheproblemofthedifferenceofdisplacementbetweenantagonistcables.However,thisstillleaveduswithacontrolproblem,whenthecablesarefixedonlytotheuppervertebrae.Here,theproblemisnotthatthevertebraewillmoveoneaftertheothereachjointactasdirectingaxisandthespringsdistributetheforcesacrossallvertebrae.Whenattachingabigloadtothespinehereabout2kg,therewillbesomebucklingproblems,ifthespringsarenotstrongenough.3ScrewsinsteadofcablesTosolvethebucklingproblemoftheprecedentsolution,inathirddesign,thecableswerereplacedbyscrewsandcardanjointsseeFig6.Ateachlevel,wenowfindfourscrewsinsteadofcables.Thescrewshavedifferentstepdependingonthelevelsmallstepatlowerlevelandincreasingforhigherlevel.Thiscreatesadifferenceofdisplacementbetweentwoconsecutivevertebrae.Thedifferentscrewsarelinkedwithcardanjoints.Withthissystem,thedisplacementofeachvertebraisundercontrol.Thedrawback,still,isthattoachievethedesiredbendingofthespine,thestepofthescrewlocatedatthelastlayerbecomesverybigand,thus,requiresalargerintervalbetweentwovertebrae.Thus,thefinalprototypewouldendupbeinglargerthanoriginallyplanned.4HydraulicsystemsAfterthecablesandscrewtransmission,wehavedecidedtoexplorehydraulicsolutions.ThefirstdesignispresentedinFig7.Eachvertebraeislinkedtothenextoneusingasphericalbearing.Thistimeagain,eachvertebraeconsistsofacrossshape.EachFig.6.ThelinkbetweentwovertebraeisacardanjointandcompressionspringsareplacedoneachbranchtoinsurethestabilityFig.7.Thelinkbetweentwovertebraeisacardanjointandcompressionspringsareplacedoneachbranchtoinsurethestabilitybranchacrosstwovertebraeislinkedthroughatwistedtube.Betweentwotubes,thevertebraeisdrilledtoleaveawayfortheliquid.Thuseachstackoftubesformaextensiblecolumn.Ahydraulicpumphasbeendesignedspecificallyforourpurpose.Thepumpislocatedatthebaseofthespine.Twomotorstransmitthemovement,viaasetofreductiongears,totwoparallelendlessscrewsthatmovestwopistonsinsidetubesseeFig8.Thiscreatesapumpin/pumpouttractionsystem,similartousingapairofsyringes,seeFig.9.Prototypesoftwistedtubehavebeenproducedtotesttheresistanceofsuchasystem.Theprototypesweretestedunderapressureof3bartheminimalpressurerequiredtomovealoadof2kgSeeIII.Noneofthetubeswehavetestedweresufficientlyresistanttosuchpressure.Thesensitivepointsarethefoldoftheaccordionshapedtubes.Theseproblemshavedrivenustoamoreclassicalsolutionbyusingpistonsinsteadofcompressibletubes.Thepistonsaremuchmoreresistanttohighpressure,buttheproblemisthedifferenceoffrictionbetweentheFig.8.Cutviewofthetractionsystem.Fig.9.Workingprincipleofthehydraulicactuationofthespine.Fig.10.Dimensionsofthetorso.differentpistons.Weareunabletoguaranteethatallpistonswillhavethesamecomportment.ThatcanresultinthespinalcordforminganSshape.Topreventthisproblem,wehaveplacedfourspringsbetweeneachvertebrae.B.Prototypeofa3DOFsspinalcordThecurrentprototypeofspineisabout200mmhighforadiameterof90mm.Itsweightisabout1Kganditcansupportaloadof2Kglocatedat80mmonthespineseeFig.12.ThehydraulicpumpinlocatedatitsbaseseedescriptioninIIIA.4,and,thus,isnotpartofthesupportingload.Thecompletespineiscomposedoffourvertebrae,linkedthroughsphericalbearing.AteachlevelFig.11.Maximumbendingofthespine