机械手相关的外文文献.docx

机械手相关的外文文献.docx

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机械手相关的外文文献

附件一:

ARapidlyDeployableManipulatorSystem

Author:

ChristiaanJ。

J。

Paredis,H.BenjaminBrown，PradeepK.Khosla

Abstract：

Arapidlydeployablemanipulatorsystemcombinestheflexibilityofreconfigurablemodularhardwarewithmodularprogrammingtools,allowingtheusertorapidlycreateamanipulatorwhichiscustom-tailoredforagiventask.Thisarticledescribestwomainaspectsofsuchasystem,namely，theReconfigurableModularManipulatorSystem（RMMS）hardwareandthecorrespondingcontrolsoftware。

1Introduction

Robotmanipulatorscanbeeasilyreprogrammedtoperformdifferenttasks,yettherangeoftasksthatcanbeperformedbyamanipulatorislimitedbymechanicalstructure。

Forexample,amanipulatorwell—suitedforprecisemovementacrossthetopofatablewouldprobablynobecapableofliftingheavyobjectsintheverticaldirection.Therefore，toperformagiventask,oneneedstochooseamanipulatorwithanappropriatemechanicalstructure。

Weproposetheconceptofarapidlydeployablemanipulatorsystemtoaddresstheabovementionedshortcomingsoffixedconfigurationmanipulators.AsisillustratedinFigure1,arapidlydeployablemanipulatorsystemconsistsofsoftwareandhardwarethatallowtheusertorapidlybuildandprogramamanipulatorwhichiscustomtailoredforagiventask.

ThecentralbuildingblockofarapidlydeployablesystemisaReconfigurableModularManipulatorSystem（RMMS）。

TheRMMSutilizesastockofinterchangeablelinkandjointmodulesofvarioussizesandperformancespecifications.OnesuchmoduleisshowninFigure2。

Bycombiningthesegeneralpurposemodules，awiderangeofspecialpurposemanipulatorscanbeassembled。

Recently，therehasbeenconsiderableinterestintheideaofmodularmanipulators，forresearchapplicationsaswellasforindustrialapplications。

However,mostofthesesystemslackthepropertyofreconfigurability，whichiskeytotheconceptofrapidlydeployablesystems.TheRMMSisparticularlyeasytoreconfigurethankstoitsintegratedquick-couplingconnectorsdescribedinSection3。

EffectiveuseoftheRMMSrequires，TaskBasedDesignsoftware。

Thissoftwaretakesasinputdescriptionsofthetaskandoftheavailablemanipulatormodules；itgeneratesasoutputamodularassemblyconfigurationoptimallysuitedtoperformthegiventask。

Severaldifferentapproacheshavebeenusedsuccessfullytosolvesimpli—fiedinstancesofthis

Athirdimportantbuildingblockofarapidlydeployablemanipulatorsystemisaframeworkforthegenerationofcontrolsoftware。

Toreducethecomplexityofsoftwaregenerationforreal—timesensor-basedcontrolsystems,asoftwareparadigmcalledsoftwareassemblyhasbeenproposedintheAdvancedManipulatorsLaboratoryatCMU.Thisparadigmcombinestheconceptofreusableandreconfigurablesoftwarecomponents，asissupportedbytheChimerareal-timeoperatingsystem，withagraphicaluserinterfaceandavisualprogramminglanguage,inplementedinOnika.

Althoughthesoftwareassemblyparadigmprovidesthesoftwareinfrastructureforrapidlyprogrammingmanipulatorsystems，itdoesnotsolvetheprogrammingproblemitself.Explicitprogrammingofsensor—basedmanipulatorsystemsiscumbersomeduetotheextensiveamountofdetailwhichmustbespecifiedfortherobottoperformthetask。

Thesoftwaresynthesisproblemforsensor-basedrobotscanbesimplifieddramatically,byprovidingrobustroboticskills，thatis，encapsulatedstrategiesforaccomplishingcommontasksintherobotstaskdomain。

Suchroboticskillscanthenbeusedatthetasklevelplanningstagewithouthavingtoconsideranyofthelow—leveldetails

Asanexampleoftheuseofarapidlydeployablesystem，consideramanipulatorinanuclearenvironmentwhereitmustinspectmaterialandspaceforradioactivecontamination,orassembleandrepairequipment。

Insuchanenvironment，widelyvariedkinematic（e.g。

workspace）anddynamic（e。

g。

speed，payload）performanceisrequired，andtheserequirementsmaynotbeknownapriori。

Insteadofpreparingalargesetofdifferentmanipulatorstoaccomplishthesetasks—anexpensivesolution—onecanusearapidlydeployablemanipulatorsystem.Considerthefollowingscenario:

assoonasaspecifictaskisidentified,thetaskbaseddesignsoftwaredeterminesthetask.ThisoptimalconfigurationisthenassembledfromtheRMMSmodulesbyahumanor，inmanipulator。

Theresultingmanipulatorisrapidlyprogrammedbyusingthesoftwareassemblyparadigmandourlibraryofroboticskills.Finally,themanipulatorisdeployedtoperformitstask。

Althoughsuchascenarioisstillfuturistic,thedevelopmentofthereconfigurablemodularmanipulatorsystem,describedinthispaper,isamajorstepforwardtowardsourgoalofarapidlydeployablemanipulatorsystem。

Ourapproachcouldformthebasisforthenextgenerationofautonomousmanipulators，inwhichthetraditionalnotionofsensor—basedautonomyisextendedtoconfiguration—basedautonomy。

Indeed，althoughadeployedsystemcanhaveallthesensoryandplanninginformationitneeds，itmaystillnotbeabletoaccomplishitstaskbecausethetaskisbeyondthesystem'sphysicalcapabilities.Arapidlydeployablesystem，ontheotherhand,couldadaptitsphysicalcapabilitiesbasedontaskspecificationsand,withadvancedsensing,control，andplanningstrategies,accomplishthetaskautonomously。

2Designofself-containedhardwaremodules

Inmostindustrialmanipulators,thecontrollerisaseparateunithousingthesensorinterfaces，poweramplifiers,andcontrolprocessorsforallthejointsofthemanipulator.Alargenumberofwiresisnecessarytoconnectthiscontrolunitwiththesensors,actuatorsandbrakeslocatedineachofthejointsofthemanipulator。

Thelargenumberofelectricalconnectionsandthenon-extensiblenatureofsuchasystemlayoutmakeitinfeasibleformodularmanipulators.Thesolutionweproposeistodistributethecontrolhardwaretoeachindividualmoduleofthemanipulator。

Thesemodulesthenbecomeself-containedunitswhichincludesensors,anactuator，abrake，atransmission，asensorinterface,amotoramplifier,andacommunicationinterface,asisillustratedinFigure3。

Asaresult，onlysixwiresarerequiredforpowerdistributionanddatacommunication。

2.1Mechanicaldesign

ThegoaloftheRMMSprojectistohaveawidevarietyofhardwaremodulesavailable.Sofar,wehavebuiltfourkindsofmodules：

themanipulatorbase，alinkmodule,threepivotjointmodules（oneofwhichisshowninFigure2），andonerotatejointmodule.Thebasemoduleandthelinkmodulehavenodegrees—of-freedom;thejointmoduleshavedegree—of-freedomeach.ThemechanicaldesignofthejointmodulescompactlyfitsaDC—motor,afail-safebrake,atachometer,aharmonicdriveandaresolver

Thepivotandrotatejointmodulesusedifferentoutsidehousingstoprovidetheright—angleorin—lineconfigurationrespectively，butareidenticalinternally。

Figure4showsincross-sectiontheinternalstructureofapivotjoint.EachjointmoduleincludesaDCtorquemotorand100：

1harmonic-drivespeedreducer，andisratedatamaximumspeedof1。

5rad/sandmaximumtorqueof270Nm.Eachmodulehasamassofapproximately10.7kg.Asingle,compact,X-typebearingconnectsthetwojointhalvesandprovidestheneededoverturningrigidity。

Ahollowmotorshaftpassesthroughalltherotarycomponents,andprovidesachannelforpassageofcablingwithminimalflexing.

2。

2Electronicdesign

Thecustom-designedon-boardelectronicsarealsodesignedaccordingtotheprincipleofmodularity。

EachRMMSmodulecontainsamotherboardwhichprovidesthebasicfunctionalityandontowhichdaughtercardscanbestackedtoaddmodulespecificfunctionality。

ThemotherboardconsistsofaSiemens80C166microcontroller,64KofROM,64KofRAM,anSMCCOM20020universallocalareanetworkcontrollerwithanRS-485driver,andanRS—232driver。

ThefunctionofthemotherboardistoestablishcommunicationwiththehostinterfaceviaanRS—485busandtoperformthelowlevelcontrolofthemodule，asisexplainedinmoredetailinSection4.TheRS—232serialbusdriverallowsforsimplediagnosticsandsoftwareprototyping。

Astackingconnectorpermitstheadditionofanindefinitenumberofdaughtercardswithvariousfunctions,suchassensorinterfaces，motorcontrollers,RAMexpansionetc。

Inourcurrentimplementation,onlymoduleswithactuatorsincludeadaughtercard.Thiscardcontainsa16bitresolvertodigitalconverter，a12bitA/Dconvertertointerfacewiththetachometer，anda12bitD/Aconvertertocontrolthemotoramplifier；wehaveusedanofthe-shelfmotoramplifier（GalilMotionControlmodelSSA—8/80）todrivetheDC—motor。

Formoduleswithmorethanonedegree-of-freedom,forinstanceawristmodule,morethanonesuchdaughtercardcanbestackedonto由es创nemotherboard.

3Integratedquick-couplingconnectors

Tomakeamodularmanipulatorbereconfigurable,itisnecessarythatthemodulescanbeeasilyconnectedwitheachother.Wehavedevelopedaquick—couplingmechanismwithwhichasecuremechanicalconnectionbetweenmodulescanbeachievedbysimplyturningaringhandtight;notoolsarerequired。

AsshowninFigure5，keyedflangesprovidepreciseregistrationofthetwomodules。

Turningofthelockingcollaronthemaleendproducestwodistinctmotions:

firstthefingersofthelockingringrotate（withthecollar）about22。

5degreesandcapturethefingersontheflanges;second，thecollarrotatesrelativetothelockingring，whileacammechanismforcesthefingersinwardtosecurelygripthematingflanges.Aball—transfermechanismbetweenthecollarandlockingringautomaticallyproducesthissequenceofmotions。

Atthesametimethemechanicalconnectionismade,pneumaticandelectronicconnectionsarealsoestablished.Insidethelockingringisamodularconnectorthathas30male