外文翻译平行数字控制机床的制造业工序的运动仿真英文版.pdf

Front.Mech.Eng.China(2006)2:173176DOI10.1007/s11465-006-0020-4ZHANGJian-min,FANYu,JIADong-yun,ZOUQiu-ling,WUYingKinematicsimulationofaparallelNCmachinetoolinthemanufacturingprocessHigherEducationPressandSpringer-Verlag2006AbstractAimedatenhancingtheresearchstatusofparallelmachinetools,thispaperintroducesthestructureofa6-SPSparallelmachinetoolandexplainstheapplicationsignificanceofthekinematicsimulationofthemanufacturingprocess.ThesimulationsoftwarewasdevelopedinMicrosoftVisualC+6.0usingOpenGLAPIfunctions.Thedataflowsarepresented.Finally,asimulationapplicationofoddleafhyperboloidisperformedbeforethemanufacturingprocess；thekinematicsimulationdemonstratestherationaleoftraceplanningandthefeasibilityofmanufacturinginstruction.Keywordskinematicsimulation,parallelNCmachinetool,manufacturingprocess,traceplanning1IntroductionParallelNCmachinetool,alsoknownasvaried-axisNCmachinetool,virtualspindlemachinetool,andparallelrobot,isanovelnonlineartoolbasedonnonlinearStewartmechanismsanddiffersfromtraditionallineartools.Inthepastdecades,thetoolhasreceivedagreatdealofattentionfrommanyresearchers,anditsdevelopmentandapplicationshaveachievedmanyimprovements1,2.Duringthisperiod,thekinematicsimulationsystemofparallelNCmachinetoolshasalsobeendevelopedasapracticaltoolandplaysagreatroleinparallelmachinetooldesignandresearch.Kinematicsimulationhasnowbeenappliedinmanyaspectsoftooldesign；forexample,itcanexplorethedimensionaltargetandsearchtheterminaledge；itcanalsocheckthevalidityoftraceplanning.Furthermore,thesafetyofthewhollyproducedunitcanbeensuredbyreal-timecheckingofthecollisionandinterferenceoftheNCmachinetool3.Therearemanyarticlesonthedevelopmentofasimulationsystem.Mostoftheseareconstructedonanexistingsimulationsystem,whichmakestheapplicationquickly,butalsobringssomeproblems:hugedevelopmentinvestmentandinfeasibleapplicationinfreefromfeatureobjecttraceplanningsimulation.InallusiontoparallelNCmachinetoolapplication,thispaperintroducesadevelopmentmethodofkinematicsimulationusingOpenGLAPIfunctionswithMSVisualC+4.2Thestructureofa6-SPSparallelNCmachinetoolAsshowninFig.1,OXYZisastaticcoordinateofthebaseplatformandPXYZisamobilecoordinateofthemobileplatform.Accordingtothereversekinematicmodel:jjjIPPAB=+(1)wherejIisthevectoroflegdirection,Pisthevectorfromtheoriginpointofthemobilecoordinatetotheoriginpointofthestaticcoordinate.jPisthevectorfromthecenterpointofthemobileplatformspherejointtotheoriginpointofthemobilecoordinate.jBisthevectorfromtheoriginpointofthestaticplatformtothecenterpointoftheuniversejoint.Aisthetransformationmatrix,alsocalleddirectioncosinematrix.Inthepastdecades,Stewartplatformresearchhasreceivedagreatdealofattentionandhasbeenappliedinawidevarietyofequipment,suchasflightsimulators,parallelrobotmanipulators,machinetools,six-degrees-of-freedomcoordinatemeasuringdevices.Inpracticalterms,the6-SPSparallelNCmachinetoolisbasedontheStewartplatformandhassomepotentiallyadvantageouspoints,suchassimplerstructure,higherRESEARCHARTICLEZHANGjian-min(),FANYu,JIADong-yun,ZOUQiu-ling,WUYingSchoolofMechanicalEngineeringandAutomation,BeijingInstituteofTechnology,Beijing100081,ChinaE-mail:174stiffness,heavierloadingability,morestablekinematicproperties.Fig.1Six-SPSstructureandvectorsketch.a6-SPSparallelNCtoolsketchb1.Staticpiatform2.Universaljoint3.leg4.spherejoint5.mainspindle6.mobileplatform7.baseplatformFig.2Themaininterfaceofthesimulationsystem3ThesignificanceofmanufacturingsimulationThemovementofthe6-SPSparallelNCmachinetoolisconfinedbyitsownstructuralcharacteristics:Thelengthofeachlegconfinestheposeandposition.Theswinganglelimitofthespheresubsidiaryream.TheinterferencebetweenthelegsTherefore,thecuttingtoolofparallelmachinetoolsmustbeplacedinsideacertainworkingspace.However,whenmanufacturingacomplicatedfreefromsurfacepart,itisdifficulttodeterminewhetherthecuttingtoolissafelyplacedinsidetheworkingspaceandwhetherthemanufacturingcodeisinaccurate,incomplete,orunreasonable.Codevalidation,includingformatchecks,completenesschecks,reasonablenesschecks,andlimitchecks,mustbeperformedbyasimulationsystembeforethemanufacturingprocessbegins.ThemanufacturingprocessissimulatedtoensurethattheNCprogramiserror-freeandcapableofperformingitsintendedtrace.Obviously,alloftheseprocesseshavepracticalsignificancetothemanufactureofparallelmachinetools.4ThedesignofthesimulationsoftwarePrincipleThesimulationsoftwarewasdevelopedinMSVisualC+usingOpenGLAPIfunctionsrunningunderWindows2000.Accordingtotheprincipleofmodulardesign,thesystemdevelopmentusesobject-orientedprogrammingtechniquestoensuresystemstructuremodularizationanddiscreteness.Toensuretherobustnessandreproducibilityofthesystem,allcoremodulesusetheComponentObjectModelanddatacommunicationbetweensystemmodulesisbasedontheCommunicationComponentInterface.Theinputsourceoftraceplanningsimulationisthecuttingtoolposefile,whichincludestheCartesiancoordinatesofthecuttingtoolpointandthenormalvectorofthecuttingtoolbar.Thesimulationisperformedaccordingtoalinearpatternandtimelinearity.Underthecircumstancesthatthesimulationprocessdoesnotgobeyondanyconfinedcondition,thetraceplanfilewillproducethefileoftheextensionquantityofthoselegsthatisrequiredbythepracticaluses.ThemaininterfaceofthesimulationsystemisshowninFig.2.Somemainfunctionoptionsarelisted,suchastrackprogramming,simulation,andelongationoftheextensionlegs,etc.Themainviewframeisathree-dimensional(3D)substantialmodeloftheparallelmachinetool.Ontherightareaofthemainviewframe,threesubframesareplacedfromtoptobottom,whichareusedrespectivelytocontrolthevisualangleforobservationandtoshowtheparameteroftheknifesposepositionandtheextensionquantityofthoselegs.ThemoduleofthemanufacturingprocesssimulationsystemisshowninFig.3.TwocoremodulesaretheTracePlanProgrammingmoduleandtheManufacturingProcessSimulationmodule.Theformerusesthetraceplanfiletoproducethecorrespondingcuttingtoolpositionfile；thelatterinputsthecuttingtoolpositionfiletosimulatethemanufacturingprocess.175Fig.3Thestructureof6-SPSparallelNCmachinetoolmanufacturingprocesssimulationsystemWhenthekinematicsimulationperformstheinitialization,theFileFormatmoduleopensthetraceplanfileandchecksthefiledata,thenconfiguresthesystemdata；aftercheckingthevalidityofthetooltracedata,thesystembeginstoperformthemanufacturingprocesskinematicsimulationaccordingtothecuttingtooltracefile.Duringthisprocess,thesystemonlychecksthesafetyoftheworkingspace.Assoonastheconfinedconditionexists,thecorrespondingjudgmentfunctionandactionareactivated.Soawarningisgivenautomaticallytoinformtheuserwhathappenedandwhaterroroccurred.Inordertosimulatethepracticalmanufacturingprocess,theparameterofavirtual3Dobjectmustbeidenticalwiththeparameterofthepracticalparallelmachinetool.AllofthesedataarequeriedbythesystemandareconfiguredintheParameterConfigurationmodule.Thesedatarepresentthepracticalsizeof6-SPS,suchastheabsolutecoordinatevalueofsixuniversaljointcentersonthestaticplatform,thecoordinatevalueofthesixspherejointcentersonthemobileplatforminthemobilereferenceframe,theinitiallengthoftheleg,thediameterandthelengthofthecuttingtoolbar,andthespherereamradius,etc.ThefunctionofthePoseandVectorCheckmoduleistocheckthevalidityofthetracedataanddeterminewhetherthecuttingtoolposeisinsidetheworkingspace.TherelationshipbetweenthecoordinatesofthecuttingtoolpointandthedirectioncosineofthenormalvectorisgovernedbyEq.1.Accordingtothislaw,theparametersofthemobileplatform,includingthecoordinatesofthesixsphericaljointcenters,arecalculated.Thenthelengthsofthesixlegsarecalculated.ThedataflowchartisshowninFig.4.TheinputsourceoftheManufacturingProcessSimulationmoduleisthecuttingtooltracefile；thisfileincludesinformationabouttheposition(X,Y,Z)andpose(a,b,c)ofthecuttingtool,whereX,Y,Zarethepositioncoordinatesofthecuttingtoolpointanda,b,ctheposewhichcanbewrittenintheformofthreedirectioncosines.Thesystemloadsthesedataintoadatabufferandthenexchangesthedoubledisplaybuffer,sothemanufacturingprocesscanbedisplayeddynamically.ThedataflowchartisshowninFig.5.Fig.4DataflowoftheposeandvectorcheckmoduleFig.5TheflowofkinematicsimulationThecontrolfile,alsocalledthepracticalmanufacturingcontrol(PMC)file,istheNCcodedriverfile.Ingeneral,thetracefileisatemporarymiddlefilethatcontainsinformationabouttraceplanning.Aftercheckingtheposeandvectorofthetracefile,thevalidityandcorrectnesscanbeensured.Afterthekinematicsimulationisperformed,therationalityoftraceplanningcanbeconfirmed.However,practicalmanufacturingrequiresthePMCfile.Accordingtothecontrolrequirementsoftheparallelmachinetool,theFileFormatI/OCheckmoduleproducestheconsistent176PMCfilewiththetracefile.ThedataflowoftheresultingPMCfileisshowninFig.6,whererfileisthestateparameter.Fig.6DataflowoftheproducedPMCfileTheTracePlanmoduleisthecoremoduleinthemanufacturingprocesskinematicsimulation.Whenthesurfaceofpracticalpartsisselected,thismoduleproducesthecuttingtooltraceplanfile.Thestepsintheconfigurationareasfollows:choosethetracetype；inputtheparameter.Setthetraceorder,suchasparallellinemode,borderlinemode,andsoon.Afteralltherequiredparametervaluesareconfigured,theTracePlanmodulefiguresoutthediscretepointscoordinatevalueofthespecialsurfaceaccordingtotherequirementsofinterpolationprecisionandEq.1.ThesedataarewrittenintothetracefileusingaparticulardataformatshowninFig.7.Fig.7Cuttingtooltracefile5simulationofoddleafhyperboloidOddleafhyperboloidisakindoftypicalcomplicatedsurface；itsequationis:2222221xyzabc+=(2)wherea=10,b=6,c=8.Thestepsinthesimulationareasfollows:configurethetracetypeandinputtheneededparameters,suchasvelocity,interpolationperiods,andlengthofthecuttingtoolbar.ThenclickonthemenuofTrace/Createfiletoproducethetracefile,asshowninFig.9.Aftercheckingthefilevalidity,clickthebuttontobeginthemanufacturingprocesssimulation.Thesystemgetsthedatafromthebufferatthesametimeanddisplaystheposition,pose,andlengthofthelegs.Ifthetracefilehasanerror,thesystemchecksitanddisplaysamessagetoindicatetheerrortypeandposition.6ConclusionsIngeneral,thekinematiccontroloftheparallelmachinetoolismorecomp