毕业设计机械手外文翻译.docx

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1、外文翻译译文题目一种与移动机械臂的局部零件所受载荷相协调的运动结构(2)原稿题目AkinematicallyCOmPatibleframeworkforCOoPeratiVePaylOadtransportbySonholonomicmobilemanipulators(2)原稿出处AUtOnRobot(2006)21:227-242Akinematicallycompatibleframeworkforcooperativepayloadtransportbynonholonomicmobilemanipulators(2)M.Abou-Samah1,C.P.Tang2,R.M.Bhatt2

2、andV.Krovi2(1) MSCSoftwareCorporation,AnnArbor,Ml48105,USA(2) MechanicalandAerospaceEngineering,StateUniversityofNewYorkatBuffalo,Buffalo,NY14260,USAReceived:5August2005Revised:25May2006Accepted:30May2006Publishedonline:5September2006AbstractInthispaper,weexaminethedevelopmentofakinematicallycompati

3、blecontrolframeworkforamodularsystemofwheeledmobilemanipulatorsthatcanteamuptocooperativelytransportacommonpayload.Eachindividuallyautonomousmobilemanipulatorconsistsofadifferentially-drivenWheeledMobileRobot(WMR)withamountedtwodegree-of-freedom(d.o.f)revolute-jointed,planarandpassivemanipulatorarm.

4、Thecompositewheeledvehicle,formedbyplacingapayloadattheend-effectorsoftwo(ormore)suchmobilemanipulators,hasthecapabilitytoaccommodate,detectandcorrectbothinstantaneousandfiniterelativeconfigurationerrors.Thekinematica11y-compatib1emotion-planning/controlframeworkdevelopedhereisintendedtofacilitatema

5、intenanceofallkinematic(holonomicandnonholonomic)constraintswithinsuchsystems.Givenanarbitraryend-effectortrajectory,eachindividualmobi1e-manipu1ator,sbi-levelhierarchicalcontrollerfirstgeneratesakinematically-feasibledesiredtrajectoryfortheWMRbase,whichisthentrackedbyasuitablelower-levelposturestab

6、ilizingcontroller.Twovariantsofsystem-levelcooperativecontrolschemesleader-followeranddecentralizedcontrolarethencreatedbasedontheindividualmobi1e-manipuIatorcontrolscheme.Bothmethodsareevaluatedwithinanimplementationframeworkthatemphasizesbothvirtualprototyping(VP)andhardware-in-the-loop(HIL)experi

7、mentation.Simulationandexperimentalresultsofanexampleofatwo-modulesystemareusedtohighlightthecapabilitiesofareal-timelocalsensor-basedcontrollerforaccommodation,detectionandcorectionofrelativeformationerrors.KeywordsCompositesystem-Hardware-in-the-loop-MobilemanipuIator-Physicalcooperation-Redundanc

8、yresolution-VirtualprototypingKinematiccollaborationoftwomobilemanipulatorsWenowexaminetwovariantsofsystem-levelcooperativecontrolschemes-leader-followeranddecentralizedcontrol-thatcanbecreatedbasedontheindividualmobi1e-manipu1atorcontrolscheme.1.eader-followerapproachThefirstmethodofmodelingsuchasy

9、stemconsidersthemidpointofthemobilebase(MPB)ofthemobi1e-manipuIatorBtoberigidlyattachedtotheend-effectorofmobilemanipulatorA,asdepictedinFig.4.Figure4(b)depictshowtheend-effectorframe用ofMPAisrigidlyattachedtotheframeatMPB(separatedbyaconstantrotationangle).co0anj3Xg0Yt(15)Fig.4Schematicdiagramsofthe

10、leader-followerscheme:(a)the3-linkmobilemanipulatorunderanalysis,and(b)thetwo-modulecompositesystem(*),玦),g(2),MPBnowtakesontheroleoftheleaderandcanbecontrolledtofollowanytrajectorythatisfeasibleforaWMR.Hence,givenatrajectoryoftheleaderMPBand the preferred manipulator configuration of( M(e)(5) can b

11、e rewritten as:X，_co8XYi=sin/5cob0Y；三inco-rfcc4-in,rfLj+LcosLjco空1.ISm%+三nC0Sinyc07-smqi323-Lsin11.11三)Ljc03Ljcott0|彳(16)andcorrespondinglyEqs.(6)-(8)as:(17)(部三(2)+M)xi-jx(%7rco也Thus,thetrajectoryofthevirtual(reference)robotforthefollowerMPA(Xf,F,CIvf).u4C),andthederivedvelocitiescannowbedetermined.

12、Thisformstheleader-followerschemeusedforthecontrolofthecollaborativesystemcarryingacommonpayload.DecentralizedapproachThesecondapproachconsiderstheframeattachedtoapointofinterestonthecommonpayloadastheend-effectorframeofboththeflankingmobilemanipulatorsystems,asdepictedinFig.5.Thus,adesiredtrajector

13、yspecifiedforthispayloadframecanthenprovidethedesiredreferencetrajectoriesforthetwomobileplatformsusingthesimilarframeworkdevelopedintheprevioussectionbytaking人工3=and0*),wherek=A,B.ThispermitsEq.(5)toberewrittenas:气4AilkYieo4-4coV一mVsin/cosFig. 5 Decentralizedcontrolschemeimplementationpermitsthe(a)

14、compositesystem;tobetreatedas(b)twoindependent2-linkmobilemanipulatorsS=慧)，=(), (tvi),kd v 上 W * Yd(kiVandcorrespondinglyEq.(6)-(8)as:(19)Eachtwo-linkmobilemanipulatornowcontrolsitsconfigurationwithreferencetothiscommonend-effectorframemountedonthepayload.However,thelocationsoftheattachmentsofthephy

15、sicalmanipulatorswithrespecttothepayloadreferenceframemustbeknownapriori.ImplementationframeworkWeexaminethedesignanddevelopmentofatwo-stageimplementationframework,showninFig.6,thatemphasizesbothvirtualprototyping(VP)basedrefinementandhardware-in-1he-1oop(HIL)experimentation.Fig. 6 Paradigmforrapidd

16、evelopmentandtestingofthecontrolschemeonvirtualandphysicalprototypesVirtualprototypingbasedrefinementInthefirststage,weemployvirtualprototyping(VP)toolstorapidlycreate,evaluateandrefineparametricmodelsoftheoverallsystemandtestvariousalgorithmsinsimulationwithinavirtualenvironment.3Dsolidmodelsofthem

17、obileplatformsandthemanipulatorsofinterestarecreatedinaCADpackage,andexportedwiththeircorrespondinggeometricandmaterialpropertiesintoadynamicsimulationenvironment.Figure7(a)showsanexampleoftheapplicationofsuchframeworkforsimulatingthemotionofamobileplatformcontrolledbyanalgorithmimplementedinSimulin

18、k.However,itisimportanttonotethattheutilityofsuchvirtualtestingislimitedby:(a)theabilitytocorrectlymodelandsimulatethevariousphenomenawithinthevirtualenvironment;(b)thefidelityoftheavailablesimulationtools;and(c)ultimately,theabilityofthedesignertocorrectlymodelthedesiredsystemandsuitablyinterpretth

19、eresults.Fig. 7 AsingleWMRbaseundergoingtestingwithinthe(a)virtualprototypingframework;and(b)hardware-in-the-loop(HIL)testingframeworkHardware-in-the-loopexperimentationWeemployahardware-in-the-loop(HIL)methodologyforrapidexperimentalverificationofthereal-timecontrollersontheelectromechanicalmobilem

20、anipulatorprototypes.EachindividualWMRisconstructedusingtwopoweredwheelsandtwounactuatedcasters.Conventionaldisc-typerearwheels,poweredbygear-motors,arechosenbecauseofrobustphysicalconstructionandeaseofoperationinthepresenceofterrainirregularities.Passiveballcastersarepreferredoverwheelcasterstosimp

21、lifytheconstraintsonmaneuverabilityintroducedbythecasters.Themountedmanipulatorarmhastwopassiverevolutejointswithaxesofrotationparalleltoeachotherandperpendiculartothebaseofthemobileplatform.Thefirstjointisplacedappropriatelyatthegeometriccenterontopframeoftheplatform.Thelocationofthesecondjointcanb

22、eadjustedtoanypositionalongtheslottedfirstlink.Thesecondlinkitselfisreducedtoaflatplatesupportedbythesecondjoint.Eachjointisinstrumentedwithopticalencoderthatcanmeasurethejointrotations.Thecompletelyassembledtwo-linkmobilemanipulatorisshowninFig.1.(c).Thesecondmobilemanipulator(seeleftmoduleofFig.1(

23、b)and(d)employsthesameoveralldesignbutpossessesamotoratthebasejointofthemountedtwo-linkarm.Themotormaybeusedtocontrolthejointmotionalongapredeterminedtrajectory(whichcanincludebraking/holdingthejointatapredeterminedposition).Whenthemotorisswitchedoffthejointnowrevertstoapassivejoint(withmuchgreaterd

24、amping).Themotorisincludedforpermittingfutureforce-redistributionstudies.Inthispaper,however,themotorisusedsolelytolockthejointpreventself-motionsofthearticulatedlinkageforcertainpathologicalcases(Bhattetal.,2005;TangandKrovi,2004).PWrM-OUtputmotordrivercardsareusedtodrivethegearmotors;andencodercar

25、dsmonitortheencodersinstrumentingthevariousarticulatedarms.ThisembeddedcontrollercommunicateswithadesignatedhostcomputerusingTCP/IPforprogramdownloadanddatalogging.ThehostcomputerwithMATLAB/Simulink/RealTimeWorkshopprovidesaconvenientgraphicaluserinterfaceenvironmentforsystem-levelsoftwaredevelopmen

26、tusingablock-diagrammaticlanguage.Thecompiledexecutableisdownloadedoverthenetworkandexecutesinreal-timeontheembeddedcontrollerwhileaccessinglocallyinstalledhardwarecomponents.Inparticular,theabilitytoselectivelytestcomponents/systemsatvariouslevels(e.g.individualmotors,individualWMRsorentiresystems)

27、withoutwearingoutcomponentsduringdesigniterationswasveryuseful.Figure7(b)illustratestheimplementationofsuchasystemononeoftheWMRs.Numerouscalibration,simulationandexperimentalstudiescarriedoutwiththisframework,attheindividual-levelandsystem-level,arereportedinAbou-Scimah(2001).ExperimentalresultsFort

28、hesubsequentexperiments,2weprescribetheinitialconfigurationofthetwo-modulecompositesystem,asshowninFig.8.Specifically,wepositionthetwoWMRSsuchthatMPAislocatedatarelativepositionof工一O.OOjdjOin.)y=0.61m124in.,ancjwt1arelativeorientationdifferenceof=0.00owithrespecttoMPB.Forfixedlink-lengthsthisinheren

29、tlyspecifiesthevaluesofthevariousconfigurationanglesasshowninTable1.Table1Parametersfortheinitialconfigurationofthetwo-modulecompositewheeledsystem(seeFig.8fordetails)LinklengthsofthearticulationL10.28m(11in)L20.28m(11in)RelativeanglesoftheconfigurationofthearticulationL30.28m(11in)1333.982280.07o33

30、37.36oOffsetbetweenthewheeledmobilebases1128.59o0.00oObOax0.00m(0in)0.61m(24in)Fig.8Initialconfigurationofthetwo-modulecompositewheeledsystem1.eader-followerapproachAstraightlinetrajectoryatavelocityof0.0254m/sisprescribedfortheleader,MPB.Givenadesiredconfigurationofthemanipulatorarm,thealgorithmdes

31、cribedinSection4.1isusedtoobtainadesiredtrajectoryforMPA.AlargedisruptionisintentionallyintroducedbycausingoneofthewheelsofMPAtorunoverabump,toevaluatetheeffectivenessofthedisturbanceaccommodation,detectionandcompensation.Theresultsareexaminedintwocasescenarios-CaseA:MPAemploysodometricestimationfor

32、localizationasseeninFig.9,andCaseB:MPAemployssensedarticulationsforIocalizationasseeninFig.10.Ineachofthesefigures,(a)presentstheoveral1(Xu,u)-trajectoryofMofMPAwithrespecttotheend-effectorframe(thatisrigidlyattachedtothe.ofMPB)while(b),(c)and(d)presenttherelativeorientationdifference,differenceandd

33、ifferenceasfunctionsoftime.Furtherinbothsetsoffigures,theDesired(-line)isthedesiredtrajectorytypicallycomputedoffline;and*Actual,(-o-line)thesystem,asdeterminedbypost-processingthearticulations.is the actual trajectory followed by measurements of the instrumentedHowever,inFig.9,the(-x-line)represent

34、stheodometricestimatewhileinFig.10itFig.9 Ca se A: Odom etric Estim ation ofFrame M, used in the controI of MP A followi(which therefore coincides with the Actualstands for the articulation based estimate后恐Iused for control of MPA J with respect to MP B in a leader-follower approach is able to detec

35、t and correct non-systematic errors suchFig. 10ArticulationEstimation ofCase B: based Frame M,g MPBin a leader -follow(d)erapproach,isunabletodetectnon-systematicerrorssuchaswheel-slip,(a)XYtrajectoryofFrameM;(b)OrientationversusTime;(c)XpositionofFrameMversusTime;and(d)YpositionofFrameMversusTimeas

36、wheel-slip,(a)XYtrajectoryofFrameM;(b)OrientationversusTime;(c)XpositionofFrameMversustime;and(d)YpositionofFrameMversustimeInCaseA,theintroductionofthedisruptioncausesadriftintherelativeconfigurationofthesystemwhichremainsundetectedbytheodometricestimation.Further,asseeninFig.9,thisdrifthasatendenc

37、ytogrowifleftuncorrected.However,asseeninFig.i0,thesystemcanusethearticulation-basedestimation(CaseB)tonotonlydetectdisturbancestotherelativeconfigurationbutalsotosuccessfullyrestoretheoriginalsystemconfiguration.DecentralizedcontrolapproachInthisdecentralizedcontrolscenario,astraightlinetrajectoryw

38、ithavelocityof0.0254m/sispresentedforthepayloadframe.Asintheleader-followerscenario,alargedisruptionisintroducedbycausingoneofthewheelsofMPAtorunoverabump.ThealgorithmistestedusingtwofurthercasescenariosCaseC:BothmobiIeplatformsemployodometricestimationforlocalizationasshowninFig.1_1,andCaseD:Bothmo

39、bileplatformsemploysensedarticulationsforlocalizationasshowninFig.2.化、小Fig.11CaseC:OdometricestimationofframesMofMPAandMPB,usedinthecontrolofMPAwithrespecttoMPBinthedecentralizedapproach,isagainunabletodetectnon-systematicerrorssuchaswheel-slip.(a)XYtrajectoryofframeMofMPA;(b)XYtrajectoryofframeMofM

40、PB;(c)Relativeorientation,betweenMPAandMPB,versustime;(d)Xdistance,betweenMPAandMPB,versustime;and(e)Ydistance,betweenMPAandMPB,versustime.(f)Sequentialphotographsofthecorrespondingcompositesystemmotion(astimeprogressesfromlefttorightalongeachrow)Fig.of MP A and MP B with respect to a payload-fixed

41、frame is able to detect and correct non-systematic errors such as wheel-slip, (a) XY trajectory of frame M of MP A; (b) XY trajectory of frame M of MP B; (c) Relative orientation, between MP A and MP B, versus time; (d) X distance, between MP A and MP B, versus time; and (e) Y distance, between MP A

42、 and MP B, versus time. (f) Sequential photographs of the corresponding composite system motion (as time progresses from left to right along each row)12CaseD:ArticulationbasedestimaIneachofthesefigures,subplots(a)and(b)presentstheoverall(viVtrajectoriesofframesMofMPAandMPBrespectivelywithrespecttoth

43、eirinitialposes.Subplots(c),(d)and(e)presenttherelativeorientationdifference,differenceanddifferenceofframes册ofMPAandMPBrespectivelyasfunctionsoftime.Furtherinbothsetsoffigures,theDesired(-line)isthedesiredtrajectorytypicallycomputedoffline;and4Actual,(-o-line)istheactualtrajectoryfollowedbythesyste

44、m,asdeterminedbypost-processingthemeasurementsoftheinstrumentedarticulations.However,inFig.LI,the(-x-line)representstheodometricestimatewhileinFig.12itstandsforthearticulationbasedestimate.InCaseC,bothmobileplatformsusetheodometricestimationforlocalization-henceasexpected,Fig.reflectsthefactthatthes

45、ystemisunabletodetectorcorrectforchangesintherelativesystemconfiguration.HoweverthedataobtainedfromthearticulationsaccuratelycapturestheexistenceoferrorsbetweentheframesofreferenceofMPBandMPA.Thus,usingthearticulation-basedestimationofrelativeconfigurationforcontrolasinCaseDallowsthedetectionofdistu

46、rbancesandsuccessfulrestorationoftheoriginalsystemconfigurationasshowninFig.12.Note,however,whiletherelativesystemconfigurationismaintained,errorsrelativetoaglobalreferenceframecannotbedetectedifbothWMRSundergoidenticalsimultaneousdisturbances.Detectionofsuchabsoluteerrorswouldrequireanexternalrefer

47、enceandisbeyondthescopeoftheexistingframework.ConclusionInthispaper,weexaminedthedesign,developmentandvalidationofakinematicallycompatibleframeworkforcooperativetransportofacommonpayloadbyateamofnonholonomicmobilemanipulators.Eachindividualmobilemanipulatormoduleconsistsofadifferentiallydrivenwheele

48、dWMRretrofittedwithapassivetworevolutejointedplanarmanipulatorarm.Acompositemultidegree-Of-freedomvehiclesystemcouldthenbemodularIycreatedbyattachingacommonpayloadontheend-effectoroftwoormoresuchmodules.Thecompositesystemallowedpayloadtrajectorytrackingerrors,arisingfromsubsystemcontrollererrorsorenvironmentaldisturbances,tobereadilyaccommodatedwithinthecomplianceofferedbythearticulatedlinkage.TheindividualmobilemanipulatorscompensatedbymodifyingtheirWMRbases,