外文翻譯--組合機(jī)床與控制設(shè)計(jì).doc

英語(yǔ)原文：IntegratedMachineandControlDesignAbstractInthispaper,wedescribeasystematicdesignprocedureforreconfigurablemachinetoolsandtheirassociatedcontrolsystems.Thestartingpointforthedesignisasetofoperationsthatmustbeperformedonagivenpartorpartfamily.Theseoperationsaredecomposedintoasetoffunctionsthatthemachinemustperformandthefunctionsaremappedtomachinemodules,eachofwhichhasanassociatedmachinecontrolmodule.Oncethemachineisconstructedfromasetofmodules,themachinecontrolmodulesareconnected.Anoperationsequencecontrolmodule,userinterfacecontrolmodule,andmode-switchinglogiccompletethecontroldesign.Theintegrationofthemachineandcontroldesignandthereconfigurabilityoftheresultingmachinetoolaredescribedindetail.I.IntroductionIntodayscompetitivemarkets,manufacturingsystemsmustquicklyrespondtochangingcustomerdemandsanddiminishingproductlifecycles.Traditionaltransferlinesaredesignedforhighvolumeproduction,operateinafixedautomationparadigm,andthereforecannotreadilyaccommodatechangesintheproductdesign.Ontheotherhand,conventionalCNC-based“flexible”manufacturingsystemoffergeneralizedflexibilitybutaregenerallyslowandexpensivesincetheyarenotoptimizedforanyparticularproductorafamilyofproducts.AneffortattheUniversityofMichiganaimstodevelopthetheoryandenablingtechnologyforreconfigurablemachiningsystems.Insteadofbuildingamachiningsystemfromscratcheachtimeanewpartisneeded,anexistingsystemcanbereconfiguredtoproducethenewpart.Inthispaper,wedescribehowanintegratedmachineandcontroldesignstrategycanresultinmachinetoolswhichcanbequicklyandeasilyconfiguredandreconfigured.Inordertoprovideexactlythefunctionalityandcapacityneededtoprocessafamilyofparts,RMTsaredesignedaroundagivenfamilyofparts.Givenasetofoperationstobeperformed,RMTscanbeconfiguredbyassemblingappropriatemachinemodules.Eachactivemoduleinthelibraryhasacontrolmoduleassociatedwithit.Asthemechanicalmodulesareassembled,thecontrolmoduleswillbeconnectedandthemachinewillbereadytooperate.Extensiveandtime-consumingspecializedcontrolsystemdesignwillnotberequired.SectionIIdescribeshowthemachineisdesignedfromasetofbasicmachinemodules,ThisresearchwassupportedinpartbytheNSF-ERCconnectedinawell-definedfashion,andSectionIIIdescribeshowthecontrolissimilarlyassembledfromalibraryofcontrolmodules.ThismodularconstructionofthemachineandcontrolallowsformanylevelsofreconfigurabilityasdescribedinSectionIV.ThepaperconcludeswithadescriptionoffutureworkinSectionV.II.MachineDesignOngoingworkonmanufacturingsystemconfigurationattheUniversityofMichiganaddressestheproblemofstartingfromapart(orpartfamily)descriptionandextractingthemachiningoperationsnecessarytoproducethepart(s).Theoperationsaregroupedaccordingtotolerance,orderofexecution,anddesiredcycletimeofthesystem,withtheintentionthateachoperation“cluster”canbeproducedonasinglemachinetool.TheoperationclusterconsideredhereistodrillasetofholesforthecamtowercapsonV6andV8cylinderheadsshowninFigure1.Theinputtothereconfigurablemachinetooldesignprocedureisthecutterlocationdatageneratedbyaprocessplannerforthisoperationcluster.dataincludespositioninganddrillinginformation.TheRMTdesignprocedureconsistsofthreemainstages:taskclarification,moduleselection,andevaluation.Afterabriefliteraturereview,thesethreestageswillbeoutlinedinthissection.A.RelatedresearchSincereconfigurabilityisarelativelynewconceptinmachiningsystems,thereislittle,ifany,publishedliteratureonthedesignofreconfigurablemachinetools.However,modularmachinetoolshavebeenonthemarketforseveralyears,andsomeofthepublishedarticlesonmodularrobots,modularmachinesandassemblydohavesomerelevancetothedesignofreconfigurablemachinetools.Forexample,ShinnoandItoproposedamethodologyforgeneratingthestructuralconfigurationofmachinetools.Theydecomposedthemachinetoolstructuresintosimplegeometricforms:e.g.boxes,cylinders,etc.YanandChen21,1extendedthisworktothemachiningcenterstructuraldesign.12adaptedItosmethodformodularmachinetoolsynthesisandde-velopedamethodforenumeratingmachinetoolmodules.ParadisandKhosla15determinedthemodularassemblyconfigurationwhichisoptimallysuitedtoperformaspecifictask.Onthesystemsfront,RogersandBottaci16discussedthesignificanceofreconfigurablemanufacturingsystems,andOwenetal.13developedamodularreconfigurablemanufacturingsystemsynthesisprogramforeducationalpurposes.Inourwork,traditionalmethodsofmotionrepresentationandtopology(i.e.screwtheory,graphtheory,etc.)areemployedtocapturethecharacteristicsofRMTs.Thesemathematicalschemesareusedfortopologicalsynthesis,function-decomposition,andmappingprocedures；detailscanbefoundin9.Figure1B.TaskclarificationThedesignofanRMTbeginswithtaskclarification,whichentailsanalyzingthecutterlocationdatatodeterminethesetoffunctionswhicharenecessarytoaccomplishthedesiredkinematicmotions.Therearethreesteps.First,graphsaregeneratedwhichabstractlyrepresentationPositionFeedSpindleCoolantt1t2t3t4t5t6t7t8Fig.3.High-leveloperationsequence,showingcausaldependenciesandconcurrencies.ThisabstractrepresentationofthesequenceofoperationsisderivedfromtheCLdata,andwillbeusedtodesignthesequencingcontrolthemotions.Thesegraphsarethendecomposedintofunctions,andfinallythefunctionsaremappedontomachinemoduleswhichexistinthelibrary.Agraphrepresentationofthemachinetoolstructureallowsforsystematicenumerationofalternateconfigurationsandalsoprovidesamethodofidentificationofnonisomorphicgraphs.Thegraphrepresentationisalsousedforbookkeepingtoassignmachinemodulestothegraphelements.Agraphconsistsofasetofverticesconnectedtogetherbyedges.Inusingagraphasanabstractrepresentationofamachinetoolstructure,wedefinetwodifferenttypesofvertices:type0andtype1.Avertexrepresentsaphysicalobjectwithtwoports；eachportrepresentsthelocationontheobjectwhereitcanbeattachedtoaneighboringobject.Atype0vertexhasinputandoutputportsthatarein-linewithrespecttoeachother,whereasatype1vertexhasinputandoutputportsthatareperpendiculartoeachother.Machiningtasksarealsoclassifiedastype0ortype1,dependingonwhetherthetoolisparallelorperpendiculartotheworkpiece.C.ModuleselectionCommerciallyavailablemodulesareselectedfromthemodulelibraryforeachofthefunctions(structuralaswellaskinematic)thatweremappedtothegraphinthetaskclarificationstage.Thedatastoredforeachmoduleinthelibraryincludesthehomogenoustransformationmatrixrepresentingitskinematicorstructuralfunction,thetwistvectorsupplementedbyrangeofmotioninformation,acompliancematrixrepresentingthemodulestiffness,moduleconnectivityinformation,andpowerrequirements(foractivemodulessuchasspindlesandslides).Thefirststepinmoduleselectionistocomparethehomogeneoustransformationmatricesofthemoduleswiththetaskrequirementmatrixsuchthatwhenappropriatemodulesareselectedtomeetthetaskrequirements,theproductofallmodulematricesshouldbeequaltothedesiredtaskmatrix:T=T1T2Tn.Again,theremaybemanypossiblechoicesofmodulesforagivenstructuralconfiguration.Figure6showshowdi