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THISPAPERTOBEPUBLISHEDINTHEPROCEEDINGSOFTHE1996IEEEINTERNATIONALCONFERENCEONROBOTICSANDAUTOMATIONFORMOREINFORMATION,CONTACTROGERQUINN,ASSOCIATEPROFESSORMECHANICALENGINEERINGCASEWESTERNRESERVEUNIVERSITY,2163683222DESIGNOFANAGILEMANUFACTURINGWORKCELLFORLIGHTMECHANICALAPPLICATIONSROGERDQUINN,GREGCCAUSEYDEPARTMENTOFMECHANICALANDAEROSPACEENGINEERINGFRANKLMERAT,DAVIDMSARGENT,NICHOLASABARENDTWYATTSNEWMAN,VIRGILIOBVELASCOJRDEPARTMENTOFELECTRICALENGINEERINGANDAPPLIEDPHYSICSANDYPODGURSKI,JUYEONJOLEONSSTERLING,YOOHWANKIMDEPARTMENTOFCOMPUTERENGINEERINGANDSCIENCECASEWESTERNRESERVEUNIVERSITYCWRUCLEVELANDOHIO,44106ABSTRACTTHISPAPERINTRODUCESADESIGNFORAGILEMANUFACTURINGWORKCELLSINTENDEDFORLIGHTMECHANICALASSEMBLYOFPRODUCTSMADEFROMSIMILARCOMPONENTSIEPARTSFAMILIESWEDEFINEAGILEMANUFACTURINGASTHEABILITYTOACCOMPLISHRAPIDCHANGEOVERFROMTHEASSEMBLYOFONEPRODUCTTOTHEASSEMBLYOFANOTHERPRODUCTRAPIDHARDWARECHANGEOVERISMADEPOSSIBLETHROUGHTHEUSEOFROBOTS,FLEXIBLEPARTFEEDERS,MODULARGRIPPERSANDMODULARASSEMBLYHARDWARETHEFLEXIBLEFEEDERSRELYONBELTFEEDINGANDBINARYCOMPUTERVISIONFORPOSEESTIMATIONTHISHASADISTINCTADVANTAGEOVERNONFLEXIBLEFEEDINGSCHEMESSUCHASBOWLFEEDERSWHICHREQUIRECONSIDERABLEADJUSTMENTTOCHANGEOVERFROMONEPARTTOANOTHERRAPIDSOFTWARECHANGEOVERISBEINGFACILITATEDBYTHEUSEOFAREALTIME,OBJECTORIENTEDSOFTWAREENVIRONMENT,MODULARSOFTWARE,GRAPHICALSIMULATIONSFOROFFLINESOFTWAREDEVELOPMENT,ANDANINNOVATIVEDUALVMEBUSCONTROLLERARCHITECTURETHESEAGILEFEATURESPERMITNEWPRODUCTSTOBEINTRODUCEDWITHMINIMALDOWNTIMEANDSYSTEMRECONFIGURATION1INTRODUCTION11WHATISAGILEMANUFACTURINGAGILEMANUFACTURINGISATERMTHATHASSEENINCREASEDUSEININDUSTRYOVERTHEPASTSEVERALYEARSTHEDEFINITIONOF“AGILE”,HOWEVER,ISNOTCLEAR,NORISITCONSISTENT“AGILITYTHEMEASUREOFAMANUFACTURER’SABILITYTOREACTTOSUDDEN,UNPREDICTABLECHANGEINCUSTOMERDEMANDFORITSPRODUCTSANDSERVICESANDMAKEAPROFIT”1“TODAYFACTORIESARECOMINGONLINETHATAREAGILEATTAILORINGGOODSTOACUSTOMERSREQUIREMENTS,WITHOUTHALTINGPRODUCTION”2“AGILEMANUFACTURINGASSIMILATESTHEFULLRANGEOFFLEXIBLEPRODUCTIONTECHNOLOGIES,ALONGWITHTHELESSONSLEARNEDFROMTOTALQUALITYMANAGEMENT,‘JUSTINTIME’PRODUCTIONAND‘LEAN’PRODUCTION”3THEONLYCOMMONTHREADAMONGTHEVARIOUSDEFINITIONSISTHEABILITYTOMANUFACTUREAVARIETYOFSIMILARPRODUCTSBASEDONWHATMAYBERAPIDLYCHANGINGCUSTOMERNEEDSINTHEPAST,PRODUCTIONWASGEAREDTOWARDHIGHVOLUMEPRODUCTIONOFASINGLEPRODUCTINTODAY’SMARKET,HOWEVER,THEEMPHASISISMOVINGTOWARDSMALLLOTSIZESFROMANEVERCHANGING,CUSTOMERDRIVENPRODUCTLINEFIGURE1AGILEWORKCELLADEFINITIONOF“AGILE”MANUFACTURINGHASBEENADOPTEDWHICHAPPLIESTOLIGHTMECHANICALASSEMBLYOFPRODUCTSAGILEMANUFACTURINGISTHEABILITYTOACCOMPLISHRAPIDCHANGEOVERBETWEENTHEMANUFACTUREOFDIFFERENTASSEMBLIESUTILIZINGESSENTIALLYTHESAMEWORKCELLRAPIDCHANGEOVERMEASUREDINHOURS,FURTHER,ISDEFINEDASTHEABILITYTOMOVEFROMTHEASSEMBLYOFONEPRODUCTTOTHETHISPAPERTOBEPUBLISHEDINTHEPROCEEDINGSOFTHE1996IEEEINTERNATIONALCONFERENCEONROBOTICSANDAUTOMATIONFORMOREINFORMATION,CONTACTROGERQUINN,ASSOCIATEPROFESSORMECHANICALENGINEERINGCASEWESTERNRESERVEUNIVERSITY,2163683222ASSEMBLYOFANOTHERPRODUCTWITHAMINIMUMOFCHANGEINTOOLINGANDSOFTWARERAPIDCHANGEOVERENABLESTHEPRODUCTIONOFSMALLLOTSIZES,ALLOWINGFOR‘JUSTINTIME’PRODUCTIONACENTRALTHEMEOFOURDEFINITIONOF“AGILE”MANUFACTURINGISTHEABILITYTORAPIDLYINTRODUCEMEASUREDINWEEKSNEWASSEMBLIESANDCOMPONENTSINTOTHESYSTEMINTHISSYSTEM,RAPIDCHANGEOVERISACCOMPLISHEDTHROUGHTHEUSEOFREUSABLESOFTWARE,QUICKCHANGEGRIPPERSFORTHEROBOTICMANIPULATORS,MODULARWORKTABLES,ANDPARTSFEEDERSWHICHAREFLEXIBLEENOUGHTOHANDLESEVERALTYPESOFPARTSWITHOUTNEEDINGMECHANICALADJUSTMENTTHESEFEEDERSUSEVISION,INPLACEOFHARDFIXTURING,TODETERMINETHEPOSITIONANDORIENTATIONOFPARTSGENERIC,REUSABLEVISIONROUTINESPERMITNEWPARTSTOBEADDEDTOTHESYSTEMWITHAMINIMUMOFEFFORTATESTBEDIMPLEMENTATIONOFANAGILEMANUFACTURINGWORKCELLHASBEENDEVELOPEDFIGURE1THISINCLUDESMECHANICALMANIPULATORS,FLEXIBLEPARTFEEDERS,AVISIONSYSTEMCAMERAS,FRAMEGRABBER,ANDALIBRARYOFIMAGEPROCESSINGROUTINES,ASWELLASALIMITEDNUMBEROFDEDICATEDSENSORSANDACTUATORSNEEDEDTOCOMPLETEAGIVENASSEMBLYTHECENTRALFEATUREOFSUCHAWORKCELLISACONTROLLERCAPABLEOFCONTROLLINGEACHOFTHEAFOREMENTIONEDCOMPONENTS12RELEVANCEOFCWRUWORKSEVERALCOMPANIESHAVEIMPLEMENTEDWHATMAYBECONSIDERED“AGILE”MANUFACTURINGMOTOROLAHASDEVELOPEDANAUTOMATEDFACTORYWITHTHEABILITYTOPRODUCEPHYSICALLYDIFFERENTPAGERSONTHESAMEPRODUCTIONLINE4ATPANASONIC,ACOMBINATIONOFFLEXIBLEMANUFACTURINGANDJUSTINTIMEPROCESSINGISBEINGUSEDTOMANUFACTUREBICYCLESFROMCOMBINATIONSOFAGROUPOFCOREPARTS5AGAINSTTHEBACKDROPOFSUCHWORK,THECWRUWORKCELLISINNOVATIVEINSEVERALWAYSTHEUSEOFVISIONGUIDED,FLEXIBLEPARTSFEEDERSISONEEXAMPLEANOTHERISTHEDEVELOPMENTOFSOFTWAREDESIGNPATTERNSFORAGILEMANUFACTURINGTHEOVERARCHINGDESIGNPHILOSOPHYOFQUICKCHANGEOVER,HOWEVER,ISWHATMAKESTHISWORKCELLPARTICULARLYNOVELTHECWRUWORKCELLHASBEENDESIGNEDTOBEAVERSATILEPRODUCTIONFACILITY,AMENABLETOAWIDERANGEOFAPPLICATIONSANDANENABLINGTECHNOLOGYFORFACTORYWIDEAGILEMANUFACTURING2WORKCELLHARDWARETHEAGILEWORKCELLDEVELOPEDATCWRUCONSISTSOFABOSCHFLEXIBLEAUTOMATIONSYSTEM,MULTIPLEADEPTSCARAROBOTS,ASMANYASFOURFLEXIBLEPARTSFEEDERSPERROBOT,ANDANADEPTMVCONTROLLERANIMPORTANTFEATUREOFTHEWORKCELLISTHECENTRALCONVEYORSYSTEM,WHICHWASIMPLEMENTEDUSINGSTANDARDBOSCHHARDWAREITISRESPONSIBLEFORTRANSFERRINGPARTIALLYCOMPLETEDASSEMBLIESBETWEENTHEROBOTSANDFORCARRYINGFINISHEDUNITSTOANUNLOADINGROBOTTHEROBOTSAREMOUNTEDONPEDESTALSNEARTHECONVEYORSYSTEMPALLETSWITHSPECIALIZEDPARTSFIXTURESAREUSEDTOCARRYASSEMBLIESTHROUGHOUTTHESYSTEM,AFTERWHICHTHEFINISHEDASSEMBLIESAREREMOVEDFROMTHEPALLETBYTHEUNLOADINGROBOTFINALLY,ASAFETYCAGEENCLOSESTHEENTIREWORKCELL,SERVINGTOPROTECTTHEOPERATORASWELLASPROVIDINGASTRUCTUREFORMOUNTINGOVERHEADCAMERAS21CONVEYORSYSTEMTHECONVEYORSYSTEMUSEDINTHECWRUWORKCELLISAMODELT2MANUFACTUREDBYBOSCHPALLETSARECIRCULATEDONTWOMAINCONVEYORLINESTHESELINESAREPARALLELTOEACHOTHERANDOPERATEINOPPOSITEDIRECTIONSPALLETSARETRANSFERREDBETWEENTHESETWOSECTIONSBYMEANSOFLIFTTRANSFERUNITSLTU’STHESEALLOWFORTHECIRCULATIONOFPALLETSAROUNDTHECONVEYORSYSTEMANDTHECAPABILITYTOREORDERTHEPALLETSEACHOFTHEPALLETSINTHESYSTEMISGIVENAUNIQUEIDENTIFICATIONNUMBER,ALLOWINGTHESYSTEMTOTRACKANDDIRECTITSPROGRESSSTOPSAREMOUNTEDATCRITICALPOINTSONTHECONVEYORTOCONTROLTHEFLOWOFTHEPALLETSANINNOVATIVEUSEOFTHISCONVEYORSYSTEMISTHEUSEOFSHORT“SPURLINES”ASPURFIGURE2ISSIMPLYANEXTENSIONOFTHECONVEYOR,PERPENDICULARTOTHEMAINLINEANALOGOUSTOARAILROADSPURTHISALLOWSTHEFLOWOFTHEMAINCONVEYORLINETOBEMAINTAINEDWHILEAROBOTPERFORMSANASSEMBLYATTHESPURPALLETSENTERINGASPURAREREGISTEREDINTHEROBOT’SWORLDCOORDINATEFRAMEBYANARMMOUNTEDCAMERA,ALLOWINGTHEROBOTTOPLACEORREMOVEPARTSONTHEPALLETANDAVOIDINGTHEEXPENSEOFMECHANICALREGISTRATION22ASSEMBLYSTATIONSSEVERALASSEMBLYSTATIONLAYOUTSWEREANALYZEDINCHOOSINGTHEFINALLAYOUTAFTEREVALUATINGSEVERALFEATURESOFEACHLAYOUT,INCLUDINGPLACEMENTOFTHEROBOTSRELATIVETOTHECONVEYOR,IMPACTOFFEEDERPLACEMENTRELATIVETOTHEROBOTWORKENVELOPE,ANDTHEROBOTMOTIONSNECESSARYFORAGENERICASSEMBLY,ITWASDETERMINEDTHATTHELAYOUTINFIGURE2WOULDBESTSUITTHENEEDSOFTHEWORKCELLEACHASSEMBLYROBOTISSURROUNDEDBYTWOMODULAR,REMOVABLEWORKTABLESANDTWOFIXEDFEEDINGTABLESFIGURE2THEMODULARTABLESAREEASILYEXCHANGEABLE,ALLOWINGFORSPECIALIZEDASSEMBLYHARDWARETOBEPLACEDWITHINTHEROBOT’SWORKENVELOPETHEMODULARTABLESCONTAINPNEUMATICACTUATORSANDTHISPAPERTOBEPUBLISHEDINTHEPROCEEDINGSOFTHE1996IEEEINTERNATIONALCONFERENCEONROBOTICSANDAUTOMATIONFORMOREINFORMATION,CONTACTROGERQUINN,ASSOCIATEPROFESSORMECHANICALENGINEERINGCASEWESTERNRESERVEUNIVERSITY,2163683222ELECTRICALSENSORSWHICHCANBECONNECTEDQUICKLY,ALLOWINGTHERAPIDCHANGEOFANYSPECIALIZEDTOOLINGREQUIREDFORAGIVENASSEMBLYBYDESIGNINGTHESETABLESTOBEMODULARANDEASILYEXCHANGED,DIFFERENTASSEMBLYHARDWARECANBEQUICKLYACCOMMODATEDTOACHIEVERAPIDCHANGEOVER,THEMODULARWORKTABLESAREREGISTEREDINTHEROBOT’SWORLDCOORDINATESYSTEMINTHESAMEMANNERASTHEPALLETSIEUSINGANARMMOUNTEDCAMERATHEFEEDINGTABLESAREFIXED,ANDTHEHORIZONTAL,PARTSFEEDINGCONVEYORSAREMOUNTEDTOTHEMFIGURE2WORKSTATIONLAYOUTONEDRAWBACKOFTHECONVEYOR/SPURSYSTEM,ASOUTLINEDABOVE,ISTHETIMEREQUIREDTOEXCHANGEAFULLPALLETFORANEMPTYONEDURINGTHISTIMEAPPROXIMATELY15SECONDSTHEROBOTWOULDCONCEIVABLYBEINACTIVEASIMPLESOLUTIONTOTHISPROBLEMISAMINIWAREHOUSEAFIXTUREISLOCATEDONTHEEXCHANGEABLEPORTIONOFTHEWORKTABLETOHOLDAFEWCOMPLETEDASSEMBLIESDURINGAPALLETSWAP,THEROBOTCANCONTINUETHEASSEMBLYOPERATIONWORKINGWHILETHEINCOMINGPALLETARRIVES,PLACINGTHECOMPLETEDASSEMBLIESINTHEMINIWAREHOUSEAFTERTHEINCOMINGPALLETISTRANSFERREDTOTHESPUR,THEVISIONSYSTEMREGISTERSTHEPALLETTHEROBOTPLACESTHECURRENTASSEMBLYSTILLINITSGRIPPERONTHEPALLETANDTHENPROCEEDSTOMOVETHECOMPLETEDASSEMBLIESFROMTHEMINIWAREHOUSETOTHEPALLET23FLEXIBLEPARTSFEEDERSEACHFEEDERCONSISTSOFTHREECONVEYORSFIGURE3THEFIRSTCONVEYORISINCLINEDANDLIFTSPARTSFROMABULKHOPPERTHESECONDCONVEYORISHORIZONTAL,WITHATRANSLUCENTBELTITTRANSPORTSTHEPARTSTOTHEROBOT,PRESENTINGTHEMATANUNDERLITSECTIONNEARTHEROBOTTHETHIRDCONVEYORRETURNSUNUSEDORUNFAVORABLYORIENTEDPARTSTOTHEBULKHOPPERPROPERFUNCTIONINGOFTHEFEEDERSDEPENDSONTHEPARTSBEINGLIFTEDFROMTHEBULKHOPPERINAQUASISINGULATEDMANNERMANYFACTORSINFLUENCETHEEFFECTIVENESSOFTHEINCLINEDCONVEYORTHEANGLEOFTHECONVEYORWITHRESPECTTOTHEHORIZONTAL,THEBELTPROPERTIESEGCOEFFICIENTOFFRICTION,THETYPEOFBELTCLEATED,MAGNETIC,VACUUM,ANDTHELINEARSPEEDOFTHEBELT,FOREXAMPLEFIGURE3FLEXIBLEFEEDINGSYSTEMSCHEMATICWHENDIFFERENTPARTSARETOBEFED,THEBULKHOPPERISEMPTIEDANDFILLEDWITHTHENEWPARTSIFTHEPARTSAREOFASIMILARGEOMETRY,NOCHANGESTOTHEFEEDINGSYSTEMARETYPICALLYNEEDEDSOMEPARTS,SUCHASCIRCULARORCYLINDRICALONESIEONESTHATWOULDROLLBACKDOWNTHEINCLINEMAYNEEDADIFFERENTBELTSURFACE,SUCHASACLEATEDONE,ORADIFFERENTANGLEOFINCLINATIONOVERHEADCAMERASAREUSEDTOLOCATEPARTSONTHEHORIZONTALCONVEYORSANARRAYOFCOMPACTFLUORESCENTLIGHTSISINSTALLEDWITHINEACHOFTHEHORIZONTALCONVEYORSTHESELIGHTSTOGETHERWITHATRANSLUCENTCONVEYORBELTPROVIDEANUNDERLITAREAINWHICHPARTSCANBEPRESENTEDTOTHEVISIONSYSTEMUSINGBINARYVISIONTOOLSCURRENTLYPROVIDEDBYANADEPTVISIONSYSTEMPARTSONTHEFEEDERBELTSAREEXAMINEDFIRST,THEVISIONSYSTEMLOOKSTOSEEIFAPARTISGRASPABLEIETHEPARTISINARECOGNIZED,STABLEPOSEPOSITIONANDORIENTATIONANDENOUGHCLEARANCEEXISTSBETWEENTHEPARTANDIT’SNEIGHBORSTOGRASPITWITHAGRIPPERSECOND,THEPOSEOFTHEPARTINTHEROBOT’SWORLDCOORDINATESISDETERMINEDTHISPOSE
