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AdvancesinProductionEngineering&Management ISSN1854‐6250

Volume14|Number2|June2019|pp153–165 Journalhome:apem‐journal.org

https://doi.org/10.14743/apem2019.2.318 Originalscientificpaper

  

A new architecture model for smart manufacturing: A performance analysis and comparison with the RAMI 4.0 reference model 

Resman, M.a,*, Pipan, M.a, Šimic, M.a, Herakovič, N.a aDepartment of Manufacturing Technologies and Systems, Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia 

  

A B S T R A C T   A R T I C L E   I N F O

Inthispaperweproposedanewarchitecturalmodelofthesmartfactorytoallow production experts to make easier and more exact planning of new,smartfactoriesbyusingallthekeytechnologiesofIndustry4.0.Theexistingcomplex reference architectural model of Industry 4.0 (RAMI 4.0) offers agoodoverviewof thesmart‐factoryarchitecture,but it leadstosomelimita‐tions and a lack of clarity for the users. To overcome these limitations,wehavedevelopedasimplemodelwiththeentireandverysimplearchitectureof thesmart factory,basedontheconceptofdistributedsystemswithexactinformation and the data flows between them. The proposed architecturalmodelenablesmorereliableandsimplemodellingofthesmart factorythantheexistingRAMI4.0model.Ourapproachimprovestheexistingmethodolo‐gyforplanningthesmartfactoryandmakesallthenecessarystepsclearer.AttheendofthepaperacomparisonoftheproposedarchitecturalmodelLASFA(LASIMSmartFactory)withtheexistingRAMI4.0modelwasmade.Thede‐velopedLASFAmodelwasalreadysuccessfullyimplementedinthelaboratoryenvironmentforbuildingthedemocentreofasmartfactory. ©2019CPE,UniversityofMaribor.Allrightsreserved.

  Keywords:Industry4.0;Smartmanufacturing;Smartfactory;Architecturalmodel;Referencearchitecturalmodel;RAMI4.0

*Correspondingauthor:matevz.resman@fs.uni‐lj.si(Resman,M.)

Articlehistory:Received20December2018Revised24April2019Accepted7May2019 

  

1. Introduction 

TheintroductionofIndustry4.0andwithitfactoriesofthefuturehasbecomeanimportantfo‐cus of theworld’s industry over the past fewyears. The key technologies of Industry 4.0 canhaveamajorimpactonanincreaseinefficiencyandtheavailabilityofproductionassets,raisingtheefficiencyofequipmentandproduction,andincreasingthevalueperemployee.Atthesametime, thegoalof introducing smart factories is to reducecosts, lead times,delivery times, etc.TheintroductionofthetechnologiesofIndustry4.0intothefactoriesofthefutureisessentialifwewantthesefactoriestobecomeflexibleandagile.Wefoundthatthebiggestchallengeishowtostartplanningthefactoryofthefutureorhowandwheretostartintroducingthenewtech‐nologiesofIndustry4.0intothesefactories.

Thefourthindustrialrevolutioncombinesvarioustechnologies,suchasthedigitalisationofproduction processes and systems (digital twins of production processes and systems), cloudcomputing in combination with new mathematical algorithms, artificial intelligence, digitalagents,theInternetofThings(IoT),bigdatatocreatecyber‐physicalsystems(CPS)andsmartfactories. Industry 4.0 also includes various automated systems that allow the automatic ex‐changeofdata[1].

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WecanassessIndustry4.0’sintegrationintoacompanyusingdifferentmaturitymodelsthatshow thematurity level of a company in terms of the integrated technology of Industry 4.0.Somemodels areweb‐based, self‐assessment tools, others are published in scientific journals[2].Thegroupofweb‐based,self‐assessmenttoolscoversthematuritymodelsofPwC(Pricewa‐terhouseCoopers) [3], Impuls [4], IHK (Industrie‐ undHandelskammern) [5] andVDMA (Ver‐bandDeutscherMaschinen‐undAnlagenbau)[6].Eachofthesetoolsusesdifferentapproachestounderstand Industry4.0.We foundavarietyofmodels in scientificpublications.ApopularandfrequentlymentionedarchitecturalmodelisTheReferenceArchitecturalModelIndustry4.0(subsequentlyreferredtoasRAMI4.0)[7].OthermodelsincludeTheIndustrialInternetRefer‐enceArchitecture(IIRA)[8],developedbytheIndustrialInternetConsortium,andTheStuttgartIT‐ArchitectureforManufacturing(SITAM)[2,9],developedwithinseveralresearchprojectsattheGraduateSchoolofAdvancedManufacturingEngineering.SmallerinitiativeslikeVirtualFortKnoxandFIWAREalsoprovidedata‐drivenconcepts[10,11].

Manyotherresearchershavelookedatarchitecturalmodelsofsmartfactoriesandthecon‐nectionsbetweenthesystemstheycontain.ImportantcontributionshavebeenmadebyMonos‐torietal.[12,13],Kemenyetal.[14,15],Valckenaersetal.[16]Bagherietal.[17],Leitaoetal.[18],andothers[19].Hussainetal.[20]presentedaframeworkforsustainablemanufacturingwith itsassociatedarchitecture.Vieiraetal. [21]presenteda literaturereviewof theareasofsimulation.In[22],Zhengetal.wereresearchingtheconceptualframework,thescenarios,andthefutureperspectivesofsmartmanufacturingsystemsforIndustry4.0.Zhangetal. [23]pre‐sented concepts to achieve real‐timemanufacturing, capturing and integrating three differentlayers. InLiuetal. [24] theauthorsdiscussedandcompared theconceptsof Industry4.0andcloudmanufacturing.

ThefirstpartofthispaperpresentsadetaileddescriptionofRAMI4.0,whichistakenasthebasisandreferencetoperformacomparisonwiththenewlyproposedarchitecturalmodelcon‐cept.Thesecondsectionexplainstheproposedconceptofthearchitecturalmodel(LASIMSmartFactory,referredtoasLASFA) indetail,showingall thekeyelementsofasmart factorytakenfromdifferentverticallayersofRAMI4.0andplacingthemintoatwo‐dimensionalplatform.TheacronymLASIMstandsfortheoriginalnameofthelaboratorythatproposedthenewarchitec‐turalmodel.ThemaindifferencebetweenthenewlyproposedmodelandRAMI4.0isthegraph‐icalpresentationof theelements inatwo‐dimensionalplatform.Subsequently, thenewmodelshowstheexactlocationsoftheelementsaswellastheinterconnectionsandthedirectionsofthematerial/informationflowsbetweentheelements.ThelastpartincludesacomparisonoftheLASFAmodelwiththeRAMI4.0architecturalmodelandexplainswhyourmodelismoreusefulandeasytounderstand.Thepaperconcludeswithadescriptionofourfindings.Alltheabbrevia‐tionsusedinthepaperareexplainedintheAppendixA.

2. Reference Architectural Model Industry 4.0 (RAMI 4.0) 

2.1 Brief overview 

TheorganisationsBITKOM,VDMAandZWEIdecidedtodevelopanewarchitecturemodel fortheneedsofIndustry4.0.Forthis,theytooktheSmartGridArchitectureModelasabasis[25,26].RAMI4.0isathree‐dimensionalmodelthatdescribesIndustry4.0’sspace.Onthehorizon‐talaxis,thelayersincludedifferentviews,suchasassets,functionaldescriptions,datamaps,etc.ThiscorrespondswiththeITapproachofgroupingcomplexprojectsintosubsystems.Theotherkey criteria are the lifecycle (type) and service life (instance) of the products andproductionsystemswith thevalue streamtheycontain.Theverticalaxis represents the third typeofkeyaspect, i.e., the allocation of functions and responsibilitieswithin the factories or plants. ThecombinationofalifecycleandavaluestreamwithahierarchicallystructuredapproachforthedefinitionofIndustry4.0componentsisaspecialfeatureofRAMI4.0.Themodelallowsforthelogicalgroupingoffunctionsandthemappingofinterfacesandstandards[27].

TheRAMI4.0modelisbasedontheestablishedstandardsforautomation,suchasIEC62890,IEC62264,IEC61512/ISA95,asshowninFig.1.Itcombinesthekeyelementsandtechnologiesof

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Industry4.0,integratedintoa3Dlayeredmodel.Inthisway,acomplexsystemwithinternalcon‐nectionscanbedividedintosmallerand,forabetterunderstanding,simplersubsystems[2,9].

OntherighthorizontalaxistherearetheHierarchyLayers,whichare listed inthe interna‐tional standard IEC 62264. This axis represents the various functionalities in companies andfactories.InordertopresentIndustry4.0,theaxishasbeendividedintosmallersubsets[2,9].Thelefthorizontalaxisrepresentsasustainablecycleofproductionandproduct,basedonIEC62890.Thisaxis is furtherdivided into typesand instances.The typepasses into the instancewhenthedevelopmentandtheprototypearecompleted,andtheproductisinproduction.Thesixlayersintowhichtheverticalaxisisdividedservetodescribethesplittingofthedevice,layerbylayer[2,7,9].

Fig.1ReferenceArchitecturalModelIndustry4.0(RAMI4.0)[2]

2.2 RAMI 4.0 in more detail 

TheRAMI4.0modelhassixlayersontheverticalaxisandtwoonthehorizontalaxis.Beginningwiththeverticalaxis,thefirstlayeristhe‘Assetlayer’,whichshowsthephysicalobjects,suchasmetal parts, documents, archives, diagrams, humans, etc. One layer higher is the ‘IntegrationLayer’,wheretransformationsandconnectionsofthephysicalobjectsintoadigitalworldtakesplace.Thecomponentsofthe‘Assetlayer’areconnectedwiththedigitalworldbythe‘Integra‐tionLayer’,whichdealswiththeeasyprocessingofinformationandcanbeconsideredasalinkbetween thephysical anddigitalworlds. This layer involves computer control of the process,system drivers, human‐machine interface devices, humans, bridgewires, switches, hubs, sen‐sors, RFID (Radio‐Frequency Identification), etc. The next layer is the ‘Communication layer’,which provides standardized communications between the ‘Integration layer’ and the Infor‐mationlayer.Thestandardizationisachievedwithauniformdataformat,whichisusedintheInformationlayer,whichprovidesthecontrolofthe ‘Integrationlayer’.The‘Informationlayer’holdsdatainanorganizedway.Thebasicpurposeofthislayeristoprovideinformationaboutthetotalnumberofsales,purchaseorders,suppliers,andlocations.Itholdsinformationaboutall theproductsandmaterials thataremanufactured in the industry. Italsogives informationaboutthemachinesandcomponentsthatareusedtobuildtheproducts.Itgivesinformationtocustomersandsavestheirfeedback.The‘Informationlayer’issoftwarebased,i.e.,itmightbeinthe formofapplications,data, figures,or files. In this layer the transformationof thereceivedevents indata suitable forhigher layers takesplace.Thenext layeron thevertical axis is the‘Functional layer’, which is responsible for production rules, actions, processing, and systemcontrol.Italsofacilitatesusersasperproductfeatures,likecloudservices(restore/backupfunc‐tionality). Moreover, it involves various other activities, like the coordination of components,systempoweron/off, testingelements,deliverychannels,userinputs,andfunctionsincluding,

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butnotlimitedto,alertlights,snapshots,touchscreenandfingerprintauthentication.The‘Func‐tional layer’ includes remote access andhorizontal integration. The last layer is the ‘Businesslayer’,which is composedof thebusiness strategy,business environment, andbusiness goals.Moreover, it deals with promotions and offers, target locations, advertisements, customer‐relationshipmanagement,budgetsandthepricingmodel[25,27].

Thehorizontalaxisontheleft‐handsideofFig1showsthelifecycleandvaluestreamoftheindustrialproductionprocess(Fig.2).Ithastwophases:TypeandInstance.Whentheproductisunderdevelopmentthenit is intheTypephase.Whentheproduct is inproductionit is intheInstancephase.WheneverthesameproductisunderdevelopmentagainitisintheTypephaseagain.Whencustomersbuyproducts,theproductsareintheTypephaseagain.Whentheprod‐uctsareinstalledinasystem,theyareintheInstancephaseagain.Changingthephasefromtypetoinstancecanberepeatedmultipletimes[7,25].

Thesecondhorizontalaxisrepresents theHierarchyLayer,which isshowninFig.1ontheright‐handside.TheHierarchyLayerisbasedontheinternationalstandardsforenterprisecon‐trolsystemintegration(IEC62264andIEC61512).Inadditiontothefourlayersnamed‘Enter‐prise’,‘WorkCenters’,‘Station’,and‘ControlDevice’,thelasttwolayersatthebottomareadded(butarenot includedinstandards)andarecalled ‘FieldDevice’and ‘Product’.Thelayer ‘FieldDevices’makesitpossibletocontrolthemachinesorsystemsinanintelligentandsmartway,e.g.,smartsensors.Thelayer‘Product’takesintoaccounttheproducthomogeneityandthepro‐ductioncapacitywiththeirinterdependencies.Thelayernamed‘ConnectedWorld’isatthetop.In this layer the factory can reach external partners through service networks. These layersshowthe fundamentalviews for Industry4.0organization [28‐30].TheRAMI4.0model takesintoaccountflexiblesystemsandmachines[7].

BasedonadetailedanalysisofthereferencemodelRAMI4.0thatincludesalltheelementsoftheverticalandhorizontalaxes,thereisnoexactdefinitionwithregardstohowtheindividualelementsinsideeachlayerareinterconnectedwiththeelements.Inouropinion,thoseintercon‐nectionsarecrucialandhavetobedefinedwhenplanninganewsmartfactoryorupgradinganexistingfactorytocreateasmartfactory.Oneoftheotherimportantaspectsistheintegrationofdigital twins and digital agents into distributed systems, and not as decentralised systems ineachverticallayer.ThispartisstillmissingfromRAMI4.0.

TYPE INSTANCE

DEVELOPMENTMAINTENANCE 

USAGEPRODUCTION

MAINTENANCE USAGE

CONSTRUCTION PLAN:DevelopmentConstructionComputer SimulationPrototypeetc.

CONSTRUCTION PLAN:Software UpdatesInstruction ManualMaintenance Cyclesetc.

PRODUCTION:ProductDataSerial Numberetc.

FACILITY MANAGEMENT:UsageServiceMaintenanceRecyclingScrappingetc.  

Fig.2Productlifecycle:Fromthefirstideatothescrapyard[7]

3. Proposed architectural model LASFA – LASIM smart factory 

3.1 Global description 

The LASFA architecturalmodel (LAsim Smart FActory) is a concept for how to approach theplanningandimplementationofsmartfactories.ThemodelwasbuiltbasedonRAMI4.0,fromwherewetookthehierarchyofthelayers.Wefocusedononeofthemostimportantfeaturesofsmart factories–thecommunicationsbetweensystemsinthesmart factories’distributedsys‐tems.Usingthismodel,userswillbeabletounderstandtheprincipleoperatingsmartfactories.

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Fig.3LASFAmodelwithallsystemsandprocesses

Thearchitecturalmodel isbasedon theresultsand insightsofresearchprojectsand infor‐

mation from various European industrialmanufacturers. The LASFAmodel is focused on themainaspectsofIndustry4.0,suchashorizontal integration,vertical integration,consistenten‐gineeringandsystemsthatfollowpeople’sneeds[7].

Thedevelopmentoftheproposedarchitecturalmodelisbasedonthereferencearchitecturalmodel RAMI 4.0. Unlike RAMI 4.0, the proposedmodel is two‐dimensional, whichmakes theconceptofasmartfactoryeasiertounderstand.TheRAMI4.0referencemodelisanabstractionforplanningsmartfactoriesandisthereforenotsoeasytounderstandandisnotsousefulforindustryusers.

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The LASFA architectural model, shown in Fig. 3, presents the individual systems that arecombinedintoasmartfactory.Itincludesseverallayers,aswellasabusinessprocess,thatre‐sultinaproductintheproductionlayer.Thebusinesslayerincludesthecompany'sstrategyanditsleadershipinthefutureaswellasthemonitoringandthedeliveryoforders.

Everymanufacturer has one ormore production lines (more production lines, productioncells,warehouses,manualworkplaces,etc).Theproductionlineconsistsofseverallocalproduc‐tionsystemsthatare,inthiscase,treatedasdistributedsystems.Eachlocalproductionsystemrequires its inputandoutputdata. In the followingsectionwewillpresentall theelements inFig.3inmoredetail.

3.2 Detailed description of the model 

Inthismodelwearefocusedondigitaltwinsindifferentlayers,whichmeansavirtualcopyoftherealworld.Themodelconsistsofdigitaltwinsforlogistics,productionlines,andlocalpro‐ductionprocesses.

Severalproductionlines/productioncells/warehouses/manualworkplaces,togetherformaproductionhall.Aswementionedbefore,theproposedmodelofthesmartfactoryincludesitsowndigitaltwinfortheproductionhall.Digitaltwinsplacedatdifferentlevelspresentavirtualcopyofthesystemsintherealworld.Oneoftheimportantfactsisthatthedigitaltwinswithoutdigital agentsdonotplay an important role in a smart factory, as it only represents a virtualmodelofarealproductionsystem.Withthehelpofvariousdigitalagents(eachdigitaltwinalsohasadigitalagent– localorglobal)wegetadigital twin that continually sends feedbackandnew production plans to the real world in real time. The LASFA model includes a decision‐making digital agent, despite the fact that all the digital agents are connected. At the currentstageofdevelopment,thedecision‐makingagentisstillhuman(i.e.,aworker).Inthefuture,wecanexpectthatinthecasesofproductionprocesses,wheredecisionsaboutimprovementstoasingleproductionprocessorproductionplanwillhavetobetakeninrealtime,theexpertwillbereplacedbyacomputerandadvancedsmartalgorithmsorartificial intelligence.Buttheabso‐lutedecision‐makershouldstillbetheexpert.Withsuchanapproachwewillbeable tomaketheproductionprocessmore flexibleandagile,but thesecurityandother “real‐life”decisionswillbetakenbytheexperttoensurethestablefunctioningoftheproductionprocesses.Other‐wise, if theabsolute‐decisionmakerwastobeasmartalgorithm,thiscould leadtotheuncer‐tainty,instabilityandinsecurityoftheproductionprocesses.

Fig.3showsthelinksforinformationexchangebetweenindividualsystemsinasmartfacto‐ryanddifferentlocalclouds.Themodelofasmartfactoryisbuiltinsuchawaythateachsystemis an independentunitwith its ownPlugAndProduce local control unit – distributed systems.Thisalsoallowsustoaddorremoveanindividualsystemwithoutmajorchangestotheglobalsystem.Allthesystemsinsidethemodelareinterconnected.Asitiswithothermodelsofsmartfactories,oursalsodoesnothavetheclassicpyramidshape[13].Forthesmoothoperationofasmart factory, it is alsonecessary to recordandcollect thedata fromsensorsandsave it in alocalcloud.

TheLASFAmodelincludestheconceptofremoteaccesstothesmartfactory’sdata.Thecon‐ceptprovidesaccesstosomedataviatheInternet.Userscanaccessspecificdatawithinadata‐base(Globalcloud)oversecureInternetconnections.TheGlobalcloudcanbeinsideoroutsidethe Industry4.0 factory.Usersorcustomersof theproductcanperformconditionmonitoringandchecktheprogressoftheproductbeingmanufactured.Theuserwillbeabletochangetheproduct’s configuration during itsmanufacturing or production process (changing the colour,components,andaccessories,ifitisstillpossible).Alltheexchangeofdataisperformedinrealtime,socustomersoftheproductcanmonitortheproductionandassemblyoftheproduct.

TheproductionlineinFig.4showsseveraldifferentlocalproductionprocesseswithdifferentpropertiesandrequirements.Eachlocalproductionprocesshasitsownsingle‐boardcomputer(SBC).SBCsarepowerfulenoughtorunstandardoperatingsystemsandmainstreamworkloads[31].Informationanddataexchangewithalocalcloudisprovidedthroughawirelessnetworkor an optical cable for large amounts of data and information. The data and information ex‐changeisbidirectionalduetothefeedbackcontrolperformedbylocaldigitalagents.Eachagent

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usestheinputdataandexecutestheoptimizationprocesstocalculatethenewparametersthataresentback to thereal local system.Thedigitalagentwith itsowndatabasecanmakedeci‐sionsindependently.

Fig.6showsadetailedoverviewof theproductionprocess.All theprocessparametersarerecordedandsavedintothelocalclouds.Duetothebi‐directionalcommunicationsallthesepa‐rametersareexchangedthroughthelocalclouds.Thisenablesallthedigitalagentstohaveac‐cesstothisdataandtosendnewdata,aswellastoexchangedatawithother localandglobalclouds. Each local production process involves a local digital agent that receives informationfromalocalcloud(database).Alocalagentisamathematicalmodeloranadvancedintelligentalgorithm that can also include artificial intelligence (AI). In today’s factories, this segment iscoveredbyahumanbeing.Thelocaldigitalagentsusereferenceparametersandtabulationliststochangetheparametervalues. Inthecaseofanunusualdeviation, the localdigitalagentde‐tectsanerror,reportsitandcanevenreact.Thetrendofchangingparametersmakesitpossibleto findoutwhen itwill benecessary toperformmaintenancework (changing a cuttingknife,matrix,changingoilandfilters,etc.).

An importantpartof theLASFAmodel is theclearandconcisevisualisation.Thisvisualisa‐tionenablesinternalandexternaluserstoaccessinformationabouttheconditionoftheirmanu‐facturedproductusingasecurelocalorglobalInternetaccesspoint.Users,aswellasworkersontheassembly line,canmonitoreventswithpersonalcomputers,smartphonesortablets,asproposedandshowninFig5.

Sensorsinstalledintherealsystemsareusedtocapturetheprocessparametersandvisual‐ize them(forexample, the totalproduction in theenterprise,whichmeanstheamountofrawmaterial stock, the number of piecesmanufactured, the defects of the production system, theidentityofa line, thenumberofworkersona line, thenumberofshiftsonaparticular line,aproductdesignplan,etc.)andalsoindigitalform,anotherdigitaltwin.Thedatacapturedfromthe production line and the data from the digital twin are collected in local clouds. The localcloudsaresynchronizedwiththeglobalcloud.Thelocalcloudsalsoincludetheconceptofdigi‐talagentsthatdecidewhichdataisimportantenoughtocaptureandwhichisnotrequiredforsubsequentoperations.

Fig.4Detailedviewofaproductionline/productioncell/warehouse/manualworkplace

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(a) (b)

Fig.5Visualisationoftheproductionprocesses(a),theproductionlogistics(b)andthelocalproductionprocessThemaingoalofdigitaltwinsistoprovidecontinuouscontroloftheproductionoperations,

systemsandprocesses.Intheeventofanunexpectedchangeorshutdown,thedigitaltwinsimu‐latesdifferentscenariosandprovidesthebestsolutionatagivenmoment inreal time. Inthisway,wehaveconstantimprovementstotherealsystemthroughafeedbackloop.Usingcommu‐nication protocols, the local clouds exchange datawith the global cloud. Usually, factories in‐cludeseveralproductionlines,manualassemblyworkplaces,warehouses,productioncellsandotherproductionsystems.Likewiththeentireproductionhallwherethedigitaltwinforlogis‐ticscooperateswithlocalclouds,thislayeralsoincludesadigitaltwinoftheproductionlinethatworkstogetherwithitsownlocalcloud.Eachsystemorprocesshasitsownlocalcloud;there‐fore,weattainacompletelydistributedsystem. In thecasewhenasystemoraprocessstopsoperating,onlyonepartoftheproductionisdisabledandnottheentireproduction,aswasthecaseinfactorieswithacentraliseddatabasesystem.Thedatacapturedintheproductionlineisstoredinthelocalcloud.

The production line has several local production processes (e.g., a deep‐drawing process,product‐assemblyprocess,awire‐bendingprocess,aplastic‐injectionprocess,etc.).Fig.6showstheconnectionsbetweenthesystemsandtheprocessesinthelocalproductionprocesses.Eachlocalproductionprocesshasitsowndigitaltwin,whichconstantlyimprovesandoptimizestherealsystemandgeneratesafeedbackloop.Ifwelookdeeperintothelocalproductionprocessitself,wecanrecognisemanylinksandlocationsfordataexchange.Eachlocalproductionpro‐cessperformsaprocess(inourcaseadeep‐drawingprocess).Thelocalproductionprocesscon‐sistsofseveralsub‐processes,inourcaseitconsistsofmeasuringsystems,ahydraulicprocess,acontrol process, and others. The sensors ensure that various data is captured on each sub‐system.Thedataiscollectedinalocalcloud.Withthisdata,itispossibletosetupadigitaltwinofthelocalproductionprocess.Theconceptisillustratedusingvariouslocaldigitalagentsandintelligentalgorithms.Theconceptalsoincludespredictivemaintenancealgorithms,whichcanbefoundintheliterature[12].Whentheparametervalueschangeoutsidetheacceptablerange,thealgorithmrecognizestheerrorandthesystemreceivestheinformationthatthepartmustbereplaced(cuttingknife,matrix,etc.).Thegoalof thedigital twin isalsotoreverse influence. Itcanchangetheparametersinthesub‐processes.Thisgivesusthebestsolutionatagivenmo‐ment.Thedatainthelocalcloudenablesustouseartificialintelligenceandmachinelearning.Atthemoment,ahumanisstillthemaindecision‐maker,butinthefuture,thecontrolwillbetakenoverbyanagentandacomputerinthebackground.Theresultofthelocalproductionprocessisaproductor a semi‐finishedproduct. In the smart factory, theproductwill alsohave itsowndigital twin (seeFig.4).For this reason, it isnecessary tocaptureall the information thatde‐scribes theproductaswell aspossible (dimensions, roughness,manufacturing tolerance, geo‐metrictolerances,etc.).Asisthecasewithalltheotherdata,theconceptalsoincludesstoringthisinformationinalocalcloud.

Fielddevicesarealsoaveryimportantpartofsmartfactories.Thedatacapturedinthefielddevices(sensors)arecollected ina localcloud,andthisdata issharedwithotherclouds.This

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systemrepresentsthedatacapturedusingRFID,temperaturesensors,humiditysensors,pres‐encesensors,differentcontrolpoints,etc.Fielddevicesusedformanufacturingprocesscontrol(valves,breakers,etc.)arecontrolledviaalocalagent.

4. Comparison of the LASFA model with RAMI 4.0 

WhendiscussingtheLASFAandRAMI4.0models,andcomparingthem,wemustbecareful,be‐causetheyaredifferenttypesofmodels.Nevertheless,wecanstillmakesomecomparisonsbe‐tween theRAMI andLASFAmodels in termsof theusefulness and clarityof thedata and theinformationflowbetweenthebuildingblocksofthesmartfactoryfortheenduser.RAMI4.0isbasedonstandardsforautomationandisverygeneric.Itoffersagoodoverviewofallthekeytechnologiesof Industry4.0andoffersvarious layersandverticalaxesas thebackboneof thesmartfactory.AsexplainedattheendoftheSection2,itleadstosomelimitationsregardinganunderstanding of the exact positioning of different technologies and functions as well as theconnectivitybetweenthem.Thismeansthattheplannersofthesmartfactorydonotknowex‐actlywheretoplaceandhowtointerconnectsomeoftheveryimportanttechnologies,likedif‐ferentkindsofdigitaltwinsanddigitalagents,whichisthemainchallengeforalltheplannersofsmartfactories.

Ontheotherhand,theLASFAarchitecturalmodelismuchmorespecificandofferstheend‐userasimplevisualizationoftheentirearchitectureofthesmartfactory,withthedefinitionoftheexactlocationsandfunctionsofthedigitaltwinsandagents,withexactinformationandthedataflowbetweenthem.Themodelshowsaverycleardistributionandtheautonomyofeverysingle building block of the smart factory, from the product to the management. The LASFAmodelis,therefore,incomparisontotheRAMI4.0model,readyfordirectimplementationintheindustrialenvironmentandguidesthesmart‐factoryplannerstepbystepfromthesmallestde‐tailofthesmartfactorytothebigpicture.Itisdevelopedspecificallyforsmart‐factoryplanninganddesign.

The linksbetween thebuildingblocksof the smart factory in theLASFAmodel are shownveryclearly;theyalsoincludethedirectionofthecommunication.Connectionscanalsobeadd‐edandgraphicallypresentedintheRAMI4.0modelbyusingtheSparxRAMI4.0Toolbox[26]

Fig.6Detailedviewofthelocalproductionprocess

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software. In this case the connections are made manually by experts, who need a lot ofknowledgetoplanallthelinksinalltheverticallayers.TheRAMI4.0modeldoesnotcomeclosetothedetailandclarityofthelinksthatareimportantforthedesign/planningofsmartfactories.

AveryimportantareacoveredbytheLASFAmodelisthatthefunctionalityofthewell‐knownERP(EnterpriseResourcePlanning),MES(Manufacturingexecutionsystem)andPLM(ProductLifecycleManagement)subsystemsarereplacedwithnewdigitaltwins,whichhaveintegrateddigitalagentssupportedbyartificialintelligence.Inthemodel,thelocationandcommunicationlinksforexchangingtheinformationanddatabetweenthedifferentdigitaltwinsinasmartfac‐toryareclearlyshown.ThesefeaturesarenotincorporatedintoRAMI4.0insuchaclearman‐ner.RAMI4.0doesnotshowthelocationwhereERP,MESandPLMareintegratedintothesys‐temandmodulesinsmartfactories,norinwhichlayerstheyareneeded,anditdoesnotshowwhichdataandinformationareneededforoperation,etc.

Table1FeaturecomparisonbetweentheproposedLASFAmodelandRAMI4.0

LASFAmodel RAMI4.0modelCommunicationconnectionsbetweensystemsandprocessesinsideasmartfactory

Allthenecessarycommunicationlinksbetweenindividualsystemsarede‐scribedindetailaswellasthedirec‐tionofcommunication(theinfor‐mationflow).

Administrationshellincludescom‐municationprotocolinaverygeneralform.Thestandarddoesnotshowtheexactconnectionbetweendifferentsystemsinsideeachlayerorverticallybetweenlayers.

ERP Includedinthemodel,thelocationandinterconnectionstoothersubsystemsareclearlydefined.

Maybeincluded,butitslocationisnotdefined.

MES DigitaltwinswithintegrateddigitalagentsareusedtocoverthefunctionoftheMESsystem.

Maybeincluded,butitslocationisnotdefined.

PLM Integratedintothearchitecturemodel,thelocation,connectionwithothersystemsandmainfunctionarede‐fined.

Itisnotincluded,butmaybeadded.Hardtodefinetheexactlocation,interconnectionswithothersysteminsidethelayeraswellasbetweendifferentlayers.

Digitalagents,artificialintelligenceLASFArepresentsdifferentlocalandglobaldigitalagents,whicharebasedonmathematicalalgorithms/models.

Nolocationsforintegrationofdigitalagentsinthemodel.

Visualisationofproductionprocessandsystems

TheLASFAmodelincorporatesvisual‐isationindifferentlayers.Visualisa‐tioninsmartfactoriesisavailableintheproductionhalllayer,productionlinelayerandinthelocalproductionprocesslayer.

Notclearlydefined.

Digitaltwin Thedigitaltwinisthemainfeatureofoursmartfactorymodel.Thedigitaltwinisnecessaryforvisualisationindifferentlayers,systemsoperation,anddecisionmaking.Thedataforthedigitaltwin’soperationiscollectedinseverallocaldatabases.

Themodel doesnotshowtheexactlocationofthedigitaltwinsanditsfunctionwithinthestructure.

Visualisationofadecentralisedanddistributedsystem

Everylocalproductionprocesshasitsownlocalcloud,whichisconnectedwithotherlocalcloudsoverawirelessnetwork.Alocalcloudandamicro‐computerformadecentralisedsys‐tem.

Mainlythevisualizationofdecentral‐isedsystems.Distributedsystemsarebrieflyvisualized.

Definesallthesmartfactorysystemsandcomponentswiththeirbi‐directionallinks

Mostofthekeyelementsareincluded. Notclearlydefined

Captureandexchangeofdatabetweenprocessesandlocalclouds

Detaildescriptionofthelocalandglobalcloudsandthedirectionofthedataexchange.

Notclearlydefined–sensors,smartdata,connections

Includedstandardsforautomation Somestandardsareincludedandmorecanbeimplemented.

Somestandardsareincluded,othersareinprogress,indevelopment

A new architecture model for smart manufacturing: A performance analysis and comparison with the RAMI 4.0 … 

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Anotheradvantageofourmodel,incomparisontoRAMI4.0,isthatitincludesdifferentdigi‐talagents,whicharebasedonmathematicalalgorithms/modelsaswellasartificialintelligence,wherenecessary.Inourmodelweproposetwotypesofdigitaltwinsandagents:localandglobal.

Inouropinion,thevisualisationofthesystemsandprocessesisveryimportantinsmartfac‐tories.BycomparingtheLASFAandRAMI4.0architecturalmodels,wecanseethattheLASFAmodel includes visualisation,which is presented in the various layers of smart factories. It isnecessarytovisualisetheproductionhall,theproductionlineandthelocalproductionprocess‐es.Theproposedmodelincludesdifferentvisualisations,suchasavisualisationofthedecentral‐isedanddistributedsystem, thevisualisationof all the importantandnecessarymodulesandsystemsofsmartfactories,andthelocationsforcapturingandexchangingdataandinformationbetweenlocalprocessesandlocal/globalclouds.

Thedigitaltwinisthemainfeatureofourmodel.Thedigitaltwinisnecessaryforthevisuali‐sationofdifferentlayers,fortheoptimisationofsystemsandprocessesandfordecisionmaking.Thedataforthedigitaltwiniscollectedfromeverylocalproductionprocessaswellasthepro‐ductionlineandisstoredindifferentlocalclouds(databases).RAMI4.0doesnotclearlyindicatehowthesystemsandprocessesofsmartfactoriescooperatewitheachother.

Theproposedarchitecturalmodelofthesmartfactoryenablesmorereliable,simpleandeasymodellingofasmartfactorythantheexistingRAMI4.0oneveryscale,fromthesmallandsim‐pletothebigandcomplexproductionsystems.Itenablesprofessionalsintheproductionenvi‐ronment to see clearly all thedetailsof thedistributed conceptof the smart factory; they seeveryclearlywhereintheprocessandinthesystemtheyhavetopositiontheglobaldigitalagentandallthelocaldigitalagentsaswellaswheretopositionthedifferenttypesofdigitaltwinsoftheprocesses,systemsandproducts.Themodelalsogivestheend‐userveryclearinformationabout how to establish all the connections for data and information flow among the digitalagents,digitaltwinsandalltheotherbuildingblocksofthesmartfactory.Therefore,itisaverysuitableandhelpfultoolforprofessionalsintheproductionenvironment.AcomparisonofthemainfeaturesofbothmodelsispresentedinTable1.

5. Conclusion 

In thispaperweproposed a newarchitecturalmodel calledLASFAand compared itwith theRAMI 4.0 model. The LASFA model combines different layers and shows a clear graphicalpresentationofallthekeyelementsaswellastheirinterconnectionsinatwo‐dimensionalplat‐form,whichareimportantfortheplanninganddesignofsmartfactories.Ourconceptualmodelisconstructedinaverylogicalmannerandcanhelpindustrialcompaniestransformtheirmanu‐facturingprocessesandsystemsintothefactoriesofIndustry4.0.

WeexplainedwhytheLASFAmodelisbetterforplanningsmartfactoriesthantheRAMI4.0model,which isanarchitecturalreference for Industry4.0.Wefoundmanyadvantagesofourmodel,especially thevisualisationofdigital twins, the integrationofdifferentdigitalagentsatdifferent locations and levels, an accurate inventory of the local production processwith thelocationofdatacapture, linksbetweensystems,theconceptof integratingERP,MES,andPLMintosmartfactories,etc.

On the other hand, RAMI 4.0 integrates different standards for automation, such as IEC62890,IEC62264,IEC61512.TheRAMI4.0architecturalmodelshowsaglobalviewofIndustry4.0 fromdifferent vertical layers (Asset, Integration, Communication, Information, Functional,andBusiness).Thisgivesusa complexandnot so transparent three‐dimensionalview,whichgreatlyenhancesthecomplexityofunderstanding.Inthiscaseeachlayerontheverticalaxisistreatedseparatelyandthereforewegetatwo‐dimensionalviewofeachlayer.

Theresearchdiscussedinthispapercontributesaninnovativearchitecturalmodelandkeydesignprinciples of the future factories at our laboratory. The LASFAmodel enables users toeasilyplansmartfactorieswithallthenecessarysystemsandtostudythecommunicationlinksbetween them.The architecturalmodel showsvery clearlyhow the communicationsbetweensystemstakeplace,whereitisnecessarytocapturethedatafortheplanningofdigitaltwinsindifferentlayersofasmartfactory,anditshowsthevisualizationandwhichlayertheuserscan

Resman, Pipan, Šimic, Herakovič

access, etc. The digital twin represents the main feature of a smart factory in the newly proposed model.

In our future research work we plan to constantly improve the architectural model according to the newest scientific and industrial demands. Our main focus will be the area of big data and smart data collection, which are needed as the inputs for the development of different digital twins in different layers.

Acknowledgement The work was carried out in the framework of the GOSTOP programme (OP20.00361), which is partially financed by the Republic of Slovenia – Ministry of Education, Science and Sport, and the European Union – European Regional Development Fund.

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Appendix A The list of the abbreviations in the paper:

AI Artificial intelligence BITKOM The name of German’s digital association CPS Cyber-physical system ERP Enterprise resource planning IHK Industrie- und Handelskammern IIoT Industrial internet of things IIRA The industrial internet reference architecture IoT Internet of things I/O unit Input/output unit IT Information technology LASFA LASIM smart factory LASIM Laboratory for handling, assembly and pneumatics MES Manufacturing execution system PC Personal computer PLM Product lifecycle management RAMI 4.0 Reference architectural model Industry 4.0 RFID Radio-frequency identification SBC Single board computer SITAM The Stuttgart IT-architecture for manufacturing VDMA Verband Deutscher Maschinen- und Anlagenbau

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