-1-*OUFHSBUFBOE$POUSPM%FTJHOGPS$POGJHVSBCMF.BDIJOF5PPMTD.M.TilburyandS.KotaEngineeringResearchCenterforConfigurableMachiningSystemsDepartmentofMechanicalEngineeringandAppliedMechanicsTheUniversityofMichiganAnnArbor,MI48109-2125tilbury,CTUSBDUInthispaper,wedescribeasystematicdesignprocedureforconfigurablemachinetoolsandtheirassociatedcontrolsystems.Thestartingpointforthedesignisasetofoperationsthatmustbeperformedonagivenpartorpartfamily.Theseoperationsaredecomposedintoasetoffunctionsthatthemachinemustperform,andthefunctionsaremappedtomachinemodules,eachofwhichhasanassociatedmachinecontrolmodule.Oncethemachineisconstructedfromasetofmodules,themachinecontrolmodulesareconnected.Anoperationsequencecontrolmodule,userinterfacecontrolmodule,andmode-switchinglogiccompletethecontroldesign.Theintegrationofthemachineandcontroldesignandtheconfigurabilityoftheresultingmachinetoolaredescribedindetail.,FZXPSEmachinetools,.BDIJOF%FTJHO.PEVMFTFMFDUJPO$POUSPM%FTJHO*OUSPEVDUJPOIntodayscompetitivemarkets,manufacturingsystemsmustquicklyrespondtochangingcustomerdemandsanddiminishingproductlifecycles.Traditionaltransferlinesaredesignedforhighvolumeproduction,operateinafixedautomationparadigm,andthereforecannotreadilyaccommodatechangesintheproductdesign.Ontheotherhand,conventionalCNC-basedflexiblemanufacturingsystemoffergeneralizedflexibilitybutaregenerallyslowandexpensivesincetheyarenotoptimizedforanyparticularproductorafamilyofproducts.AneffortattheUniversityofMichiganaimstodevelopthetheoryandenablingtechnologyformachiningsystems3,4.Insteadofbuildingamachiningsystemfromscratcheachtimeanewpartisneeded,anexistingsystemcanberecontoproducethenew-2-part.Inthispaper,wedescribehowanintegratedmachineandcontroldesignstrategycanresultinmachinetoolswhichcanbequicklyandeasilyconandrecon.Inordertoprovideexactlythefunctionalityandcapacityneededtoprocessafamilyofparts,CMTsaredesignedaroundagivenfamilyofparts.Givenasetofoperationstobeperformed,CMTscanbeconfiguredbyassemblingappropriatemachinemodules.Eachactivemoduleinthelibraryhasacontrolmoduleassociatedwithit.Asthemechanicalmodulesareassembled,thecontrolmoduleswillbeconnectedandthemachinewillbereadytooperate.Extensiveandtime-consumingspecializedcontrolsystemdesignwillnotberequired.SectionIIdescribeshowthemachineisdesignedfromasetofbasicmachinemodules,connectedinawell-definedfashion,andSectionIIIdescribeshowthecontrolissimilarlyassembledfromalibraryofcontrolmodules.ThepaperconcludeswithadescriptionoffutureworkinSectionIV.*.BDIJOF%FTJHOOngoingworkonmanufacturingsystemconfigurationattheUniversityofMichiganaddressestheproblemofstartingfromapart(orpartfamily)descriptionandextractingthemachiningoperationsnecessarytoproducethepart(s)6.Theoperationsaregroupedaccordingtotolerance,orderofexecution,anddesiredcycletimeofthesystem,withtheintentionthateachoperationclustercanbeproducedonasinglemachinetool.TheoperationclusterconsideredhereistodrillasetofholesforthecamtowercapsonV6andV8cylinderheadsshowninFigure1.Theinputtothereconfigurablemachinetooldesignprocedureisthecutterlocationdatageneratedbyaprocessplannerforthisoperationcluster.TheCMTdesignprocedureconsistsofthreemainstages:taskclarification,moduleselection,andevaluation11.Afterabriefliteraturereview,thesethreestageswillbeoutlinedinthissection.3FMBUFESFTFBSDISinceconfigurabilityisarelativelynewconceptinmachiningsystems,thereislittle,ifany,publishedliteratureonthedesignofreconfigurablemachinetools.However,modularmachinetoolshavebeenonthemarketforseveralyears,andsomeofthe-3-publishedarticlesonmodularrobots,modularmachinesandassemblydohavesomerelevancetothedesignofreconfigurablemachinetools.Forexample,ShinnoandIto14,15,16,17proposedamethodologyforgeneratingthestructuralconfigurationofmachinetools.Theydecomposedthemachinetoolstructuresintosimplegeometricforms:e.g.boxes,cylinders,etc.YanandChen18,1extendedthisworktothemachiningcenterstructuraldesign.Ouyangetal.9adaptedItosmethodformodularmachinetoolsynthesisanddevelopedamethodforenumeratingmachinetoolmodules.ParadisandKhosla12determinedthemodularassemblyconfigurationwhichisoptimallysuitedtoperformaspecifictask.Chen2addressedtheproblemoffindinganoptimalassemblyconfigurationforspecifiedtasks；hisprocedurewasbasedontheassemblyincidencematrixandemployedageneticalgorithmtosolvetheoptimizationproblem.Onthesystemsfront,RogersandBottaci13discussedthesignificanceofreconfigurablemanufacturingsystems,andOwenetal.10developedamodularreconfigurablemanufacturingsystemsynthesisprogramforeducationalpurposes.Fig.1Inourwork,traditionalmethodsofmotionrepresentationandtopology(i.e.screwtheory,graphtheory,etc.)areemployedtocapturethecharacteristicsofCMTs.Thesemathematicalschemesareusedfortopologicalsynthesis,functiondecomposition,andmappingprocedures；detailscanbefoundin7.2.TaskclarificationThedesignofanCMTbeginswithtaskclarification,whichentailsanalyzingthecutterlocationdatatodeterminethesetoffunctionswhicharenecessarytoaccomplishthedesiredkinematicmotions.Therearethreesteps.First,graphsare-4-Fig.2generatedwhichabstractlyrepresentationthemotions.Thesegraphsarethendecomposedintofunctions,andfinallythefunctionsaremappedontomachinemoduleswhichexistinthelibrary.Thebasicfunctionalityofamachinetoolisdescribedbythekinematicmotionbetweenthetoolandtheworkpiece.Thesekinematicfunctionswillberepresentedbyahomogeneoustransformationmatrix8；thedesiredfunctionalityofthemachinetoolwillbeencodedinthematrixT.Themotionsnecessarytocarryoutagivenmachiningtaskarederivedfromthesequenceofope