外文翻译原文-基于标准化的数字信息处理的PLC软件的自动生成

AutomatedPLCSoftwareGenerationBasedonStandardizedDigitalProcessInformationMartinBergert,ChristianDiedrichMagdeburgUniversityInstituteofAutomationTechnology(IFAT)Magdeburg/GJensKiefer,ThomasBrDaimlerChryslerResearch&TechnologyFunctionandProductionModeling(GR/EPF)Ulm/GAbstractInordertomeetthevariouschallengesintheautomotiveindustry,newandintegratedmethodologiesforproductionplanningandramp-upprocessesarerequired.Thus,aconceptforautomatedPLCsoftwaregenerationbasedonstandardizeddigitalprocessinformationisintroducedwiththespecialfocusontheneedsofthebodyshopintheautomotiveindustry.ThefoundationforPLCsoftwaregenerationisadigitalprocessplanthatdescribestheproductionstepsinagraphicalway.ForthespecialneedsofPLCsoftwaregenerationnewprocesselementsandattributesareintroduced.SotheprocessplancontainsthestepwisespecializationofallnecessaryinformationforaPLCprogram.Thispaperadditionallypresentsaspecificationextendingthedigitalprocessinformationwithresource-specificPLCfunctionblocks.1.IntroductionDuetotheincreasingcompetitionforkeymarketshares,carmanufacturersareengagedinaninnovationracecharacterizedbyasoaringnumberofproductvariants.Inparallel,theinnovationandmodelcyclesareconstantlydecreased.Theseintensifiedcompetitiveconditionsinevitablyleadtohighercomplexitybothinoverallproductionplanningandinramp-upprocesses.Moreover,thetimeforthefutureaccomplishmentofproductionengineeringprojectshasbeencuttothebone.Today,theactivitiesintheproductionplanningpro-cess(mechanicaldesign,electricaldesign,controlengineering)areaccomplishedinamostsequentialway.Especiallythetasksofthecontrolengineeringdonotbeginbeforethemechanicaldesignisnearlycom-pleted.Inadditiontothatthereisadeepgapbetweenmechanicaldesignandcontrolengineering.Thisphenomenonisshownespeciallyindifferentworkingmethodologies,tools,andintheuseofdifferent,department-specificterms.Theresultsofthesedepart-ment-specificdifferencesinevitablyleadtolossofinformation,repeatedmanualinputs,additionallyiterationloopsaswellashightimepressureforthePLCproject(PLC:ProgrammableLogicController).Inordertocopewiththesechallengesnewplanningmethodologiesarenecessarytoencouragesimul-taneousengineering.Asoneimportantcontribution,anewmethodologyforautomatedPLCsoftwaregenerationisintroducedinthispaper.Togiveanover-view,thepaperstartswithashortdescriptionofimpor-tantandrepresentativeapproachesregardingthistopic.Basedontheidentifiedadvantagesanddisadvantagesoftheexistingapproaches,requirementstowardsanewandintegratedmethodologyforautomatedPLCsoft-waregenerationaredescribed.Afterashortintroductionoftheconceptofdigitalfactory,thenewmethodologyfulfillingthementionedrequirementsispresented.TheseveralstepsfromthedigitalprocessplantoanIEC61131-3conformPLCprogramaredescribed.Finally,thepracticalapplica-bilityofthenewmethodologyisshownusingadaptedandenhancedcommercialsoftwaretools.2.ExistingapproachesforautomatedPLCsoftwaregenerationInthefollowingsectionsdifferentrepresentativeapproachesforautomatedPLCsoftwaregenerationarepresented.Moreover,theconcept-specificadvantagesanddisadvantagesareworkedout.2.1.DFGprojectDisPa(DistributedProcessAutomation)WithintheresearchprojectDisPaanobject-orientedmethodologywasdevelopedthatallowsthegenerationofexecutablePLCsoftwarecodebasedonanabstract,system-neutralmodel1.ThismodelisdevelopedwithanextensionoftheformaldescriptionlanguageUML(UML:UnifiedModelingLanguage)thatwasadaptedtothespecialrequirementsofcontrolengi-neering.BytheuseofUMLamodularandstructuredmodeldevelopingisguaranteed.Tosupportaccele-ratedandtransparentengineeringprocessesstandardizedandreusablesoftwarecomponentsare1-4244-0826-1/07/$20.002007IEEE352used.TheconceptofUML-basedPLCsoftwaregenerationwasimplementedusinganelementaryexampleofscreeningplantwith28sensorsand19actors.WithaspecialdevelopedsoftwaretranslatortheUMLmodelistranslatedtoIEC61131-3conformPLCsoftwarecode.AfterwardsthiscodeisimportedasStructuredText(ST)inthePLCprogrammingtoolCoDeSys1.2.2.AutomatedPLCsoftwaregenerationbasedonPetriNetsIn2and3aconceptforautomatedPLCsoftwaregenerationbasedonSignalInterpretedPetriNets(SIPN)ispresented.ThebasicideaissimilartotheUML-approachfromtheresearchprojectDisPa.AnalogtotheformaldescriptionlanguageUML,SIPNallowsatransparentgraphicaldescriptionofprocess-orientedcontrolalgorithms.WithspecialsoftwaretranslatorstheseSIPNcanbetranslatedinexecutableILcode(IL:InstructionList).Forprototypicalapplica-bilityademonstratorwasdevelopedthatcreatesILcodefromSIPNrelatedtoPLCopenstandardbasedontheprogramMathematica.Thus,SIPNnotonlyarespecificationtoolsbutalsotheycanbeusedasadequatePLCprogramminglanguage2.Oneimpor-tantadvantageofSIPNtowardstheprogramminglanguagesdefinedinIEC61131-3areSIPN-specificalgorithmsthatanalysisautomaticallythetransparencyandcorrectnessoftheprograms3.2.3.VRbasedPLCsoftwaregenerationrelatedtoOsmersThedissertationfromOsmers4focusestheimprovementofPLCprojectingwiththeaidoftechniquesfromVirtualReality(VR).Duringtheplanningprocessthemanufacturingcellisconfiguredinavirtualenvironment.ThePLCprogrammingtakesplacethesamemodel.Thisisdoneinagraphical,interactiveway.BasefortheautomatedgenerationofPLCcodearetheelectricalresources(sensors,actuators).Theseobjectsareembeddedas3D-graphicsinthecellmodel.InanextstepthesesingleobjectsarelogicalconnectedwithBooleanoperatorsbytheuseofpreconfiguredinteractionswithuser(visualprogramming).Withtheaidofaspecialdeveloped,proprietaryIL-compilertheseinformationareconvertedfromthevirtualrealitytoolinmachine-readableform.ThenthegeneratedPLCcodeisdownloadedinaPLCprogrammingtool.Thesoftware-specifictransferoftheconceptdevelopedbyOsmerswasaccomplishedwiththevirtualrealitytoolVRT(SuperscapeLTD)andthePLCprogrammingtoolSTEP7(Siemens).2.4.BMBFprojectMODALEFocusoftheBMBF-projectMODALE(MODALE:ModellbasiertesAnlagenengineering)isthecompany-widedataexchangebetweendifferentdepartmentsthatareinvolvedintheplanningprocessofanautomatedmanufacturingcell5.Forthis,anontology-basedreferencemodelisdevelopedthatembeddedinatechnicalinfrastructureactsascentraldatadial.Basedonthesetechnicalconditionsdatafromdigitalplanningtoolsareexportedandtransferredtotheontology-basedreferencemodelwiththehelpofsemanticbridges.Thereadatatransformationtakesplaceandthegenerateddataareimportedintherespectivetargetapplication6.Soitispossibletoex-changedigitalplanninginformationbetweendifferentITtoolswithoutloosingimportantinformation.TheprototypictransferofthisITinfrastructureandtheverificationoftheprincipallyoperabilitywasdemonstratedusingelementaryexamples.Oneprac-ticalscenariofocusestheautomatedgenerationofaPLCSequentialFunctionChartrelatedtoIEC61131-3.BasemodelisadigitalprocessplanthatisdevelopedintheproductionplanningandenhancedwithPLC-specificinformation(e.g.transitions)7.ThismodelisexportedwithaspecialdevelopedRDF-interface(RDF:ResourceDescriptionFramework),transformedwiththeaidofthereferencemodelandfinallyimportedinthetargetsysteminformofaSFC.ThedevelopingofthedigitalprocessplanisdonewiththedigitalprocessplanningtoolDELMIAProcessEngineer(DPE)fromthecompanyDELMIA.TheusedPLCprogrammingtoolisOpenPCS,developedanddistributedbythecompanyinfoteam.2.5.PLCsoftwaregenerationwithProcessSimulateCommissioningIncontrasttothepresentedapproachesinprecededsectionstheITtoolProcessSimulateCommissioningrepresentsacommercialsoftwaretoolthatwasdeve-lopedin2002byacooperationofTecnomaticsandSiemens.BasefortheautomatedPLCsoftwaregenera-tionisadigital3Dcellmodelandthedigitalprocessdescriptionofthiscell.AnalogtothedevelopedapproachintheprojectMODALE,thedigitalprocessdescriptionisenhancedwithcontroltechnicalinfor-mation,e.g.I/O-signals.Theenhancementtakesplaceeitherbymanualaddingofnecessaryparametersorbyconnectingofresources(clamps,valves,robotsetc.)withthecorrespondingoperationsinthedigitalprocessmodel8.WiththisenhancedprocessmodelandasoftwaretranslatordevelopedbySiemensanexe-cutablePLCprogramforthePLCprogrammingtoolSTEP7canbegenerated.SothegeneratedprogramcontainsallrelevantI/O-signalsinthesymboltableaswellasaSFCthatdescribestheprocessflowinS7Graph.3532.6.EvaluationIntheprevioussectionsdifferentapproachesfortheautomatedPLCsoftwaregenerationwerepresented.Theseapproachesbaseondifferentassumptions,methodologiesandITtools.Regardingapotentialuseintheplanningprocessofmanufacturingcells,alltheseapproacheshavetheirspecificadvantagesanddisadvantageswhicharecomparedintable1.ConceptAdvantagesDisadvantagesDisPA(UML)Object-orientedmodelingbyuseofUMLGenerationofST-andSFC-codeNointegrationinplanningprocessAdditionaldevelopmentoftheUML-modelandsoft-ware-translatorNobidirectionaldataexchangepossiblePetriNet(SIPN)FormalandflexibledescriptionlanguageAutomatedverificationofthe“PLC-model”possibleSupportofPLCexchangeformatrelatedtoPLCopenNointegrationinplanningprocessAdditionaldevelopmentoftheSIPNLimitedPLCsoftwaregenerationGenerationofILcodeonlyOsmersIntegrationinplanningprocessGraphical(visual)PLCprogrammingAdditionalITtoolandsoftwaretranslatornecessaryGenerationofILcodeonlyNobidirectionaldataexchangepossibleMODALEIntegrationinplanningprocess(Useofexistingdigitalplanninginformation)Basedoncommercialsoftwaretools(DPE)GenerationofSFC-codeOnlygenerationofsimplifiedandlimitedSequentialFunctionChartsBasedonnon-standardizedexchangeformat(RDF)HugemanualeffortforreworkingProcessSimulateCommis-sioningIntegrationinplanningprocess(Useofexistingdigitalplanninginformation)BasedoncommercialsoftwaretoolsGenerationofSFCcodeOnlygenerationofsimplifiedandlimitedSequentialFunctionChartsNoopensysteminterfaces,onlyconnectiontoSTEP7(Siemens)NobidirectionaldataexchangepossibleTable1.Existingapproaches.Comparingthedifferentconceptsitisnotablethattheacademicapproachesallhavewellstructuredandflexiblebasisconceptsbytheuseofformaldescriptionlanguages(UML,SIPN).Butforpracticalusetheyarenotsuitablebecauseofthedemonstrateddisadvantages(additionalmodels,specificsoftwaretranslatorsetc.).Areversedviewisgivenbythepracticalconcepts.TheseapproachesbaseoncommercialITplanningtools,buttheyhaveproblemswithtool-specificinflexi-bility,openprogramminginterfacesaremissing.ThisleadstosimplifiedandfunctionallimitedPLCpro-gramsaswellastohugemanualreworkingeffortforthesesoftwareprograms.Untilnowapracticableandeconomicalsolutiondoesnotexist.3.RequirementsforPLCsoftwaregenerationBasedonthedescribeddisadvantagesinthepre-vioussection,afewrequirementsresulttowardsanewconceptforautomatedPLCsoftwaregeneration.TheserequirementsrefertothemethodologyaswellastotheusedITtools.Indetail,theserequirementsare:No(little)additionalaffordForeconomyandgeneraluseracceptanceitisessentialthatanewmethodologycausesaslessaspossibleadditionaleffortduringtheplanningpro-cess.UsingexistingplanningresultsToavoidrepeatedmanualdatainputsandlossofinformationduringthetransferofplanningresultsfromoneplanningtooltoanotherone,standardizedinterfacesbetweenthetoolsanddataexchangeformatsarenecessary.UpdatefunctionforprocesschangesDuringramp-upandproductionprocesses,processchangesareoftennecessary,e.g.fortheintegrationofnewproductvariants.SoitisessentialthatthesechangescanbeintegratedinthePLCprogramsduringtherunningproductionprocess.GenerationofPLCsoftwareaccordingtoIEC61131-3TheautomaticallygeneratedPLCcodehastofulfillallrestrictionsfromtheIEC61131-3tobeportableinthedifferentcommercialPLCprogrammingtools.MaintainablePLCprogramcodeItisnecessarytogeneratePLCcodeinareadableandunderstandableformatsothatlaterchangesinthesoftwarecodearepossible.ThereforethegraphicallanguagesSFCorFBD(FBD:FunctionBlockDiagram)aremuchmoresuitablethanthecrypticlanguageIL.BidirectionaldataexchangeForpracticalapplicabilityofautomatedPLCsoft-waregenerationitisnecessarytore-transferchangesinthePLCprogramsduringtheramp-upandproductionprocessesintheplanningtools.Onlythus,theconsistencyofdataisguaranteed.3544.ConceptInthischapterthenewconceptforautomatedPLCsoftwaregenerationispresented.AfterashortdescriptionofthegoalsandmethodologiesofthedigitalfactorythestepstowardsaPLCprogrambasedondigitalplanninginformationareillustrated.4.1.DigitalFactoryThedigitalproductanddigitalfactoryaretwomainconceptsforacceleratingtheoverallproductcreationprocess.Whereasdigitalproductmeansacompletemachine-processablerepresentationofaproducttooptimizetheproductpropertiesduringtheproductdevelopmentphase,digitalfactoryrepresentsasetofinterlinkedproduct,process,andresourcemodelsthatallowallmanufacturingprocessestobecontrolledandoptimizedintermsoftimesandcosts.Thedigitalfactoryis:TheextensionoranalogyofthedigitalproductfortheproductionfacilityThebridgebetweenproductdevelopmentandproductionThedigitalrepresentationoftherealfactory9In10thedigitalfactoryisdefinedas“generaltermforanoverallnetworkofdigitalmodels,metho-dologiesandtoolsthatareintegratedbyaseamlessdatamanagement.Itsaimistheholisticplanning,eva-luation,andcontinuousimprovementofallrelevantstructures,processes,andresourcesoftherealfactoryincloseinteractionwiththeproduct.”4.2.ProcessplananditsusinginthedigitalplanningprocessThecell-specificprocessplanningtakesplaceincloseinteractionwiththeresourceplanning.Atpresent,eachprocess-planningdepartment(forexample,ProductionPlanning,MechanicalDesign,andRobotics)usesitsownprocessdescriptionlanguagenormallygeneratedinstandardspreadsheetprogramsorinotherofficeapplications.So,auniform,clear,andintegratedprocessdescriptionformatsimplydoesnotexist.Error-causingmisunderstandingsespeciallyregardingthelaterPLCsoftwaregenerationarethelogicalconsequencesoftheseindividualandoftenambiguousprocessdescriptions.Toremedythis,aclearanduniversallyapplicableprocessplanwasdeveloped.Thisintegratedprocessplanisrefinedstepbystepintheplanningsuccession.Finally,itcontainsallprocessinformationfromtheproductionplanning,mechanicaldesign,roboticsandcontrolengineering.Thus,thedigitalprocessplanisasimpleworkingmediumcombiningthetaskresultsoftheinvolveddepartmentswhichaddtheirspecificcontributiontotheprocessdesign.Furthermore,theprocessplanhasthefunctionasclearandoveralldocumentationmediumaswellascentralcommunicationplatformbetweenthedifferentdepartments.Tosumup,Figure1portraysthemostimportantgoalsoftheuseofanintegratedprocessplan.today:individual,ambiguous,andinconsistentprocessdescriptionsganttchartgoal:useofaclearandintegratedprocessplanbasedonstandardizedandconfiguredprocesselementsdocumentationmediumoftheoverallcellprocessescommunicationplatformbetweenthedifferentdepartmentsbasisfortheaccomplishmentofsimulationstudiesbasisforautomatedPLCsoftwaregenerationprocessplanlibraryoflogicelementslibraryoftechnicalprocessesactivitydiagramspreadsheetFigure1.Goalsoftheuseofanintegratedprocessplan11.Theintegratedprocessplandescribestheproductionprocessflowwithsequentialandparallelprocessesinagraphicalway.So,thereareanalogiestoSequentialFunctionChartsregardingtoIEC61131-3.ButtogenerateadequatePLCprogramsautomaticallyfromtheintegratedprocessplan,additionalprocesselementsandattributesareneeded.4.3.ProcesselementsandrequirementsfromIEC61131-3ASFCaccordingtoIEC61131-3consistsofsteps,transitionsaswellasparallelandalternativelogics.Sotheprocessplanwithsequentialandparallelprocesseshastoberefinedwithlogicalelementsdonebythecontrolengineer.Furthermore,aclassificationinmanualandauto-matedprocessesisnecessarybecausenotallprocessesinthecell-specificproductionflowarerelevantforthelaterPLCprogram.Automatedprocessesagainhavetobedividedintorobot-controlledandPLC-drivenactivities.Additionaltothesegeneralpropertiesforallprocesselements,element-specificattributesareneces-sary.355Soforexampleforalternativeandparallellogicsthenumberofbranchesisrequiredaswellastheidentificationwhethertheyarestartorendnodes.Figure2showsanoverviewoftherequiredprocesselements.TechnicalelementsechnicalelementsActivitiesctivitiesTransitionsTransitionsProcesselementsrocselementsLogicaloperationLogicaloperationParallellogicParallellogicAlternativelogiclternativelogicStartnodetartnodeEndnodendnodeFigure2.ProcesselementsforautomatedPLCsoftwaregeneration.MoreovercombinationofdifferentelementsintheprocessplanhastofollowtherulesoftheIEC61131-3,especiallythestandardforSFC.ThatmeansPLC-relevantactivitiesandtransitionshavetoalternateintheprocessplan.Analternativelogicstartsafteranactivity,followedbytransitions.Contraryafterastartofaparallellogicactivitieshavetofollow.Thedetailedcombiningrulescanbefoundin12orinIEC61131-3.4.4.ConnectionbetweenprocessesandresourcesParalleltotheprocessplanning,theresourcedesigntakesplace.Standardizedresourceelementsforthebodyshoplikeclamps,sensors,andvalvesarestoredinlibraries.In13anapproachisdescribedtoenhancethesemechanicalresourceelementswithelectricalandlogicalinformation.Amongotherthingsresource-specificPLCfunctionblocksbelongtotheselogicalinformation.ThefunctionblocksdescribetheresourcebehaviorinthePLCprogram.FurthermoretheycontainallnecessaryI/O-signalsfromtheresource.DuringtheresourcedesigntheseinternalstandardizedI/O-signalsaremappedtocell-specific,non-ambiguoussignalssothatallsignalnamesappearonlyonetimeinthewholeresourcemodel.IntheintegratedprocessplantheseveralresourceswiththeirPLCfunctionblocksarelinkedtothecorrespondingprocesselements.Thuseveryprocess“knows”onwhichresourceitiscarriedout.Forex-ample,foraclampingprocessonevalveandatleastoneclamparerequired.Todaytheconnectionbetweenprocessesandresourcesisusedforprocess-drivensimulationstudies;withthenewmethodologyitisalsonecessaryforautomatedPLCsoftwaregeneration.Hence,theprocessresourceconnectionhastobeaccomplishedforallactivitiesandtransitionsintheprocessplantotransfertheseinformationinthelaterPLCprogram.4.5.PLCsoftwaregenerationThecell-specificprocessplanisdevelopedinatop-downprocessbycooperationofthedifferentdepartmentsthatareinvolvedintheproductionplanningprocess.Sotheprocessplancontainsallprocessrelevantplanningresultsofthesedepartments.ButforgenerationofPLCprograms,forexamplemanualandrobot-controlledactivitiesarenotrelevant.ThatmeansasthefirststepthepreviouslydevelopedprocessplanhastobefilteredforonlythePLC-relevantinformation.Attheexportoftheseinformationfromtheprocessplanningtool,theprocesssequen