机械外文文献及翻译.docx

机械外文文献及翻译.docx

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机械外文文献及翻译

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MultidisciplinaryDesignOptimization

ofModularIndustrialRobotsby

UtilizingHighLevelCADTemplates

1、Introduction

Inthedesignofcomplexandtightlyintegratedengineeringproducts,itisessentialtobeabletohandleinteractionsbetweendifferentsubsystemsofmultidisciplinarynature[1].Toachieveanoptimaldesign,aproductmustbetreatedasacompletesysteminsteadofdevelopingsubsystemsindependently[2].MDOhasbeenestablishedasaconvincingconcurrentdesignoptimizationtechniqueindevelopmentofsuchcomplexproducts[3,4].

Furthermore,ithasbeenpointedoutthat,regardlessofdiscipline,basicallyallanalysesrequireinformationthathastobeextractedfromageometrymodel[5].Hence,accordingtoBow-cutt[1],inordertoenableintegrateddesignanalysisandoptimizationitisofvitalimportancetobeabletointegrateanautomatedparametricgeometrygenerationsystemintothedesignframework.Theautomatedgeometrygenerationisakeyenablerforso-calledgeometry-in-the-loop[6]multidisciplinarydesignframeworks,wheretheCADgeometriescanserveasframeworkintegratorsforotherengineeringtools.

Toeliminatenoncreativework,methodsforcreationandautomaticgenerationofHLCthavebeensuggestedbyTarkian[7].TheprincipleofhighHLCtsissimilartohighlevelprimitives（HLP）suggestedbyLaRoccaandvanTooren[8],withtheexceptionthatHLCtsarecreatedandutilizedinaCADenvironment.Otherwise,thebasicsofbothHLPandHLCtcan,assuggestedbyLaRocca,becomparedtoparametricLEGOVRblockscontainingasetofdesignandanalysisparameters.Theseareproducedandstoredinlibraries,givingengineersoracomputeragentthepossibilitytofirsttopologicallyselectthetemplatesandthenmodifythemorphology,meaningthe

shape,ofeachtemplateparametrically.

2、MultidisciplinaryDesignFramework

MDOisa“systematicapproachtodesignspaceexploration”[17],theimplementationofwhichallowsthedesignertomaptheinterdisciplinaryrelationsthatexistinasystem.Inthiswork,theMDOframeworkconsistsofageometrymodel,afiniteelement（FE）model,adynamicmodelandabasiccostmodel.Thegeometrymodelprovidestheanalysistoolswithgeometricinput.Thedynamicmodelrequiresmasspropertiessuchasmass,centerofgravity,andinertia.TheFEmodelneedsthemeshedgeometryoftherobotaswellastheforceandtorqueinteractionsbasedonresultsofdynamicsimulations.

Highfidelitymodelsrequireanextensiveevaluationtimewhichhasbetakenintoaccount.ThisshortcomingisaddressedbyapplyingsurrogatemodelsfortheFEandtheCADmodels.Themodelsarebrieflypresentedbelow.

2.1HighLevelCADTemplate—GeometryModel

Traditionally,parametricCADismainlyfocusedonmorphologicalmodificationsofthegeometry.However,thereisalimittomorphologicalparameterizationasfollows:

•Thegeometriescannotberadicallymodified.

•Increasedgeometriccomplexitygreatlyincreasesparameterizationcomplexity.

ThegeometrymodeloftherobotisgeneratedwithpresavedHLCts,createdinCATIAV5.Thesearetopologicallyinstantiatedwithuniqueinternaldesignvariables.Topologicalparameterizationallowsdeletion,modification,andadditionofgeometricelementswhichleadstoamuchgreaterdesignspacecaptured.ThreetypesofHLCtsareusedtodefinetheindustrialrobottopologically;DatumHLCtwhichincludeswireframereferencesrequiredforplacementfortheActuatorHLCTsandStructureHLCts,asseenFig.2.

Fig.2Anindustrialrobot（left）andamodularindustrialrobot（right）

ThenamesofthereferencesthatmustbeprovidedforeachHLCtinstantiationarestoredintheknowledgebase（seeAppen-dixA.4）,whichissearchedthroughbytheinferenceengine.InAppendixA,pseudocodeexamplesdescribeshowthereferencesareretrievedandhowtheyarestoredintheknowledgebase.

Theprocessstartsbytheuserdefiningthenumberofdegreesoffreedom（DOF）oftherobot（seeFig.3）andisrepeateduntilthenumberofaxis（i）isequaltotheuserdefinedDOF.InordertoinstantiatethefirstStructureHLCt,twoDatumandtwoactuatorinstancesareneeded.ReferencesfromthetwoDatuminstanceshelporientingthestructureinspace,whilethegeometriesoftheactuatorinstances,atbothendsofthelink,areusedtoconstructtheactuatorattachments,asseeninFigs.2and3.Fortheremaininglinks,onlyonenewinstanceofbothdatumandactuatorHLCtsarerequired,sincethedatumandactuatorinstancesfromadjacentlinksarealreadyavailable.AppendixA.2showsapseudocodeexampleofaninstantiationfunction.ThefirstinstantiateddatumHLCtisdefinedwithreferencetotheabsolutecoordinatesystem.TheremainingdatumHLCtinstancesareplacedinasequentialorder,wherethecoordinatesystemofpreviousinstancesisusedasreferencefordefiningthe