双臂机器人的开发（原文）.pdf

SICE-ICASEInternationalJointConference2006 Oct.18-21,2006inBexco,Busan,Korea DevelopmentofIndustrialDualArmRobot forPrecisionAssemblyofMechanicalPartsforAutomobiles Chan-HunPark,Kyoung-TaikParkandDae-GabGweon2 IntelligentMachineSystemResearchCenter,KIMM,Taejeon,Korea (Tel:+82-42-868-7127;E-mail:chparkgkimm.re.kr) 2DepartmentofMechanicalEngineering,KAIST,Taejeon,Korea (Tel:+82-42-869-3225;E-mail:dggweongkaist.ac.kr) Abstract:Generalindustrialrobotshavedefinitelimitsofapplicationbecausemostofthemhasonlyonearm.Some specialindustrialrobotshavetwoarms,buteacharmdoesthejobsseparately,thatis,eacharmiscontrolledtoperform itsreferencetrajectorywithoutdeepconsiderationsofthecooperativejob,sotheydoverysimplecooperativejobsin positionlevelasaresult.RecentlysomeJapaneseautomobilecompaniesareinterestedinusingdualarmrobotsfor assemblyofmechanicalpartsofautomobilesofwhichrobotshavetohavetwoarmsandhavetheabilityofcooperation usingpositioncontrolandforcecontrol.Wearedevelopinganindustrialdualarmrobotforprecisionassemblyof mechanicalpartsforautomobilesofwhichdegreeoffreedomis6DOFperarmand3DOFintorso.Thepayloadwillbe 10kg/armandtheout-reachbe1.5m.ThisspecificationwasdeterminedforspecialassemblyprocessesforWIACo.Ltd andRobotValleyCo.Ltd.Thedesignconceptisintroduced. Keywords:DualArmRobot,Assembly,RealTimeOS,MotionController. 1.INTRODUCTION Industrialrobotshavealreadyhadgoodrolesin variousindustrialfieldsforscoresofyearssincethey haveappeared.Thetechnologyofrobotapplicationsfor automobileindustrieshasalreadyreachedveryhigh level,sowecantconsidertheautomobileindustryand thecompanieswithoutrobots.But,untilnow,industrial robotscanthavetheirrolesinthemanyfieldsinwhich anoperatordoesthejobwithhis/hertwoarms.General industrialrobotshavedefinitelimitsofapplication becausemostofthemhaveonlyonearm.Somespecial industrialrobotshavetwoarms,buteacharmdoesthe jobsseparately,thatis,eacharmiscontrolledto performitsreferencetrajectorywithoutdeep considerationsofthecooperativejobs,sotheydovery simplecooperativejobsinpositionlevelasaresult. RecentlysomeJapaneseautomobilecompaniesare interestedinusingdualarmrobotsforassemblyof mechanicalpartofautomobilesinwhichrobotshaveto havetwoarmsandhavetheabilityofcooperationusing positioncontrolandforcecontrol5. Wearedevelopinganindustrialdualarmrobotfor precisionassemblyof mechanicalpartsforautomobiles ofwhichdegreeoffreedomis6DOFperarmand3DOF intorso.Thepayloadwillbe10kg/armandthe out-reachbe1.5m.Thisspecificationwasdetermined forspecialassemblyprocessesforWIACo.Ltdand RobotValleyCo.Ltd.Thedesignconceptisintroduced. Inthecaseofgeneralindustrialrobots,theposition referenceteachingwithateachingpendantisenough becausearobotcontrollercontrolsasinglearmwith justpositionreference.Butinthecaseofdualarmrobot, positionreachingisnotenoughbecausetwoarmshave todocooperativejobsforpartsassembly,thecontroller hastoconsidertheinteractionforcebetweentwoarms andmechanicalpartsforassembly.Off-line Program(OLP)canbeusedforthispurposebutweneed 89-950038-5-598560/06/$10C2006ICASE moreintuitiveteachingmethods.So,themaster-slave conceptisadopted.Weusetwocommercialmaster devices,eachofthemhas6DOFinput(position)and 6DOFoutput(force).Inthisconcept,thecontroller needstocomputeinverse/forwardkinematicsfor 15DOFslaverobotand12DOFmasterrobotin0.005- 0.01secondinrealtime.Soverypowerful computationalpowerisneeded.Thatisthereasonwe adoptakindofPC-basedcontroller.Wewilluse PentiumDprocessors,windowsXPprofessional,a commercialmotionboardofMotionEngineeringCo. Ltd.andRealTimeExtensionSoftwareofArdenceCo. Ltd.Controllerconceptandstructureisintroduced. 2.JOBDEFINITIONFORTHEDUALARM ROBOT Ourinterestistheautomation oftheprocessof assemblyofmechanicalpartsofanautomobile companyusingadualarmrobotsystem.Theassembly linesofgeartransmissionandconstantvelocityjoints areourtargets.Thesetwoassemblyprocessesdefinitely needso-called“cooperativetask“oftwoarmsofa worker,sosinglearmrobotscantbeappliedtothese kindsofprocesses.Thisisoneofthereasonsthatthe majorautomobilecompanieskeeptheseprocesses not-automated. Wearenotshowingthedetailsfortheassemblyof thetargetprocesses,butjustshowingthebriefpictures ofthem.Figure1showsthetransmissionassemblyline whichiscomposedofsomanygearsandshaftsand Figure2showstheconstantvelocityjoints(CVJoint) whichiscomposedoftwouniversaljointsandshafts.In thecaseofWIACo.Ltd.whichisfinancingthisproject withthegovernment,mostofproductionlinesof automobilepartshavealreadybeenautomatedwithout somespecialassemblylineswhichincludethesetwo processes.Thedualrobotisbeingdesignedforthese 3059 linestobeautomated. Thedualarmrobothastobereachedto1.5m,to handlethepayload1Okgf,toovercomethetorque 1ON-mandtomovewiththerotationalvelocityofthe 150deg/s.Therequiredrepeatabilityis0.1mm.Table 1summarizesthespecificationwhichthedualarm robotssatisfiesforthetargetprocesses. Fig.IlransmissionAssemblyLine Fig.2ConstantVelocityJointAssemblyLine kinematicstructureisverysimilartothepuma-like robots,anditsactionisexpecteddifferentfrom humanoidrobot. Ourdualarmrobothastobeappliedtotransmission assemblylinesandconstantvelocityjointassembly lines.Thesetaskneedstheend-effectersofarmshave theabilityofrotationof360degreescontinuously.Ifthe dualarmrobothasthekinematicstructureoftheleft handsideofthefigure3,thentheeacharmhastohave therotationgripperadditionally.Thus,thepayload wouldbereducedorthestrongermotorsystemwould beneeded.Thereforethekinematicstructureoftheright handsideofthefigure3isselected,andthelastjoint canbeusedtodothescrewmotionofanendeffecter, rotating360degrees,fortheassemblylines.Thesecond benifitoftheproposedkinematicstructureisso-called “kinematicdecoupling“,theinversekinematicsisvery simplyexpressedwithclosedformsolutions12. Thesearethereasonstheproposedkinematicstructure isselected. _ 0w Jv HumanoidRobotsThedualarmrobots underdevelopment Fig.3Thedifferencebetweenhumanoidrobots and thedualarmrobotunderdevelopmentinthisresearch. Figure4showsthesimpledrawingtherightarmandits designedtosatisfythespec.oftable1. Table1Thespecificationofthedualarmrobots. Out-reach Payload MaxTorque Maxspeed Repeatability 1.5m 1Okgf/arm 5ONm 150deg/s 0.1mm 3.ROBOTDESIGN Therearesomanykindofdualarmrobots,theyhave differentkinematicstructures,butmostofhumanoid robotshave3DOF-torsoand6DOF-arms.Thedualarm robotunderdevelopmentinthisresearchhasdifferent kinematicstructurefromthatofmostofhumanoid robotseventhoughtheyhavethesamedegreeof freedom.Figure3showthedifferencebetweenthem. Mostofhumanoidrobotshavethekinematicstructure similartohuman,butthekinematicstructureofourdual armisdifferentfromthem.Theleftandrightarms Fig.4Thedesignoftherightarm Fortheworkspaceanalysis,thedevelopmentof kinematicsolutionsandthevisualevaluation,thesimple dualarmanalysistoolisdeveloped.Thisprogramis underconstruction,itwillhavetheabilityofkinematic evaluationandtheverificationofcontrolalgorithms, 3060 IT7 etc. rig.3iiesigntoololaclUdlartEllrULot 4.CONTROLLERDESIGN Figure6showstheoverallstructureofthecontroller underdevelopmentwhichiscomposedofthemainhost, thevisioncontroller,thetele-operationcontrollerand therobotcontoller.AllthecontrollersarePC-based,and controllersareconnectedtoeachotherwithCANbusto communicatetoeachotherwithrealtime.Offline program,visionsystemandtele-operationisbeyondthe scopeofthispaper.Here,onlytherobotcontrolleris introduced. Lmiste CAMERA- i“,Shn,+U OnuireSystemln(HardRealtiIa _.N lrwbir Vano t1X I3 Therearetwowaysforthedevelopmentofthe robotcontrollerfordualarmrobot,thatis,the developmentofthespecialcontrolboardfordualarm robotortheuseofthecommercialmotionboards.In thisproject,akind ofPC-basedrobotcontrollerwith ZMP-syncNetmotionboardofMotionEngineeringCo. Ltd.andIndustrialPCisdeveloped.Microsoft WindosXPasOSandRTXofArdenceCo.Ltdforreal timecontolareselected.ZMP-syncNetmotionboardis ageneralmotionboard,itusesthecentralized computationtechnique,itscontrolfrequencyisreduced whenthemoreaxedarecontrolledatthesametime.It controlthe4axeswith48khzatthesametime,andit cancontrol32axesatthesametime,with2khz.The oneofthespecialfeatureisthatitusesthedigital communicationtomotordrivers(AMPs)withthe protocolSyncNetofMotionEngineering.Thesecond specialfeatureisthatMotionEngineeringsupportsthe driversoftwareforRealTimeOS,RTLinux,RTX,etc. ThegeneralmotionboardwithoutthedriversforReal TimeOScantbeusedtocomposethePC-Basedrobot controller. RTXisakindofRealTimeExtensionfor windowsXP,itsinterruptlatencyisverysmall(10us). RTLinuxisknownasoneofthebestrealtimeOS,butit isverydifficulttodevelopsoftwareintheLinux environmentforgeneralusers.ThisiswhyRTLinuxis notselected.MostofPCusersusewindowXP,andso manyusefulsoftwaredevelopmentkitshavebeen developed.Therefore,windowXPwouldbeoneofthe bestOSwiththeconsiderationofthemarket.But windowsXPdoesntsupportrealtimecomputationand itsnotperfectlystablesystem.SoRTXwith windowsXPisselected.RTXaddstheabilityofreal timecomputationtothewindowXP.Figure7showsthe functionofRTX4. Fig.6TheControllerstructure Generalrobotcontrollersareveryusefulinthe developmentofrobotsystem.Theyhaveveryuseful frameforrobotkinematicparametersandcontrol parameters.Inthecaseofsimpleserialrobot,mostof generalrobotcontrollersareavailable.Butinthecaseof thedevelopmentofveryspecialrobots,almostgeneral robotcontrollerisnotavailable.Becausetheydont haveso-called“openarchitecture“.Userscantaccess thesourcecodeforthekinematicequations,sospecial caseofrobotkinematicscantbeappliedtothegeneral robotcontrollers.Inthemarket,thereisntany commercialrobotcontrollerfordualarmrobots,the specialrobotcontrollerforthedualarmunder developmenthastobedeveloped. Fig.7RTXandwindows ArdenceCo.LtdsaysRTXsupportstheabilityofthe interruptlatencyoflOusinthesingleCPUsystem.But theresultofourtestisdifferentfromtheiropinion.So thePentiumDprocessorwithdualcoreisselected. BecauseiftheCPUhasmorethandualcoreordual CPU,thenRTXcanuseonecoreoroneCPUfully withouttheinterferencewithwindowsXP.Inthiscase, RTXguaranteestheinterruptlatencylessthan2usas theexperimentaltesteventhoughwindowsXPis shutdownwithbluescreen4. 3061 Tj61 HostProesgirie 1Tme Fig.8RTXandmultipleCPU Whenthemotionboardwhichhastheitsowncontrol algorithmandtheabilityofaxisinterpolationisusedto composedofPC-basedrobotcontroller,the synchronizationbetweenthehostandthemotion controllerismostimportant.RTXusesitsownclock, andmotionboarduseditsownclock,too.Thus,the functionofthe“snyqinterrupt“ofZMP-syncnetboard isused3. ZMPmotioncontrollersofMotionEngineeringhave theabilitytointerruptthehostataspecifiedfrequency, wherethefrequencyisamultipleofthecontrollers samplerate.Thisboard-to-hostinterruptisreferredtoas theSyncInterrupt.Forsystemsthatneedtosynchronize withthecontrollerandcalculatedatathatneedstobe senteverysample,the thefirmwareofZMPhasaflag. ThisflagiscalledtheHostProcessFlag.The HostProcessFlagcanbeusedtotellthefirmwarethat thehostisprocessingdatathatisexpectedtobe transmittedtoZMP.TheHostProcessFlagissetbythe hostafteritiswokenupbyaSyncInterruptandbefore theprocessingofitsdataandtasks.The HostProcessFlagisclearedbythehostwhenall processingisdoneandbeforegoingbacktosleepand waitingforthenextSyncInterrupt.Thefirmwareof ZMPcheckstheHostProcessFlageveryfor