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