外文翻譯--基于知識的機械設計獨立研究 英文版.pdf

_ReceivedDate:September29,2010Biography:PHYOWaiLin(1978-),male,borninShwebo,Myanmar.Ph.Dcandidate,1IntroductionProductdesignproceduredependsondesignersexperienceseriously.Byusingdesignersknowledgeandexperience,productmanufacturerscanreduceproductcostandproducehighqualityproducts.Designermust,however,drawuponexperientialengineeringknowledgesuchaspastexperiences,specificdesignrulesandprocedures.Mostdesignersneedtogetthecorrectgeometricinformation,parametersandfindnon-geometricfeatureinformationfromthemechanicaldesignhandbookmanuallywhichareprettytime-consuming.ParametricmodelingCADsystemsarebasedonthegeometricalrelationshipsbetweenparts.Partscanbetransformedbyvaryingdimensionseasily.However,non-geometricalknowledgeabouttheproductdesigncannotbemanagedeasily1.SomecommercialCADsystemsignorethisissue.ThereforeKnowledge-basedengineering(KBE)hasbeenpresentedtomeetthedemandsofengineeringdesignmethodssincethelastof1980s.KBEisasubsetofknowledgeBaseSystem(KBS)whichisaspin-offfromartificialintelligence(AI).KBEisthemethodologyforTheResearchofIndependentKnowledgeBasedMechanicalDesignPHYOWaiLin,XIPing,ZHANGBao-yuan,CHENRui-zhi(SchoolofMechanicalEngineeringandAutomation,BeijingUniversityofAeronauticsandAstronautics,Beijing100191,China)Abstract:MostofKBEsystemsappliedbypreviousresearchersaredependentonsomeCADsoftware,whichmakesknowledgehardtobereusedtootherCADsoftware.IndependentknowledgebasedsystemisindependentofCADsoftware；thereforeknowledgecanbereusedfreely.Thispaperdescribesindependentknowledgebasedsystemformechanicaldesign.Adetaileddiscussionabouttypicaldesignisputforwardincludingdesignprocessimplementationbasedonknowledgeengineering,independentknowledgebaseddesignarchitecture.Themainprincipalofknowledgedrivenengineeringisexplained.TheimplementationofKBEonthedesignofwormreducerisstudiedasacase.Independentknowledgebasedreducerdesignsystemisrealized.TheusageofindependentknowledgebasedsystemmakesKBEsystemworkindependentofCADsoftware,whichenhancestheirportabilityandfertilizesthecollaborativeworkofheterogeneousCADsystems.Keywords:knowledge-basedengineering；independentknowledgebase；reducer；KnowledgeInterpreter(KI)CLCNumber:TP391DocumentCode:AArticleID:1003-4951(2010)02-0001-07Vol.20No.2CADDMDecember2010capturingandstructuringknowledgewhichisusedtodefineengineeringmethodsandprocedures2.Typicalknowledge-basedsystemisbasedonobject-orientedprogramminglanguageandistightlyintegratedwithageometricmodelingtool,AI,designersexperience,databaseandsoon.Fig.1isthetypicalKBEdesignarchitecture.Fig.1KBEdesignarchitectureInrecentyears,theapplicationofCAx,AIandKBEtechnologieshavebeendevelopingfordesignandmanufacturingsystems.RichardCurran,WimJ.C.Verhagen,TonH.vanderLaanandMJTvanTorrenincorporatedtheKnowledgeOptimizedManufactureanddesign(KNOMAD)methodologywithinKBE3fortheanalyticalutilizationofmanufacturingknowledge.C.B.Chapman,MartynPinfolddescribesaknowledgebasedengineeringsystem(KBES)toextendthecurrentcapabilitiesofautomotivebody-in-white(BIW)engineer4.PabloBermell-GarciaandIp-ShingFanappliedKBEsystemforthedesignandmanufacturingofawindtunneltestingmodelofaircraftnacellesbyadoptionandcombinationoftheproductionrulesandtheobject-orientedknowledgerepresentation5.MostoftheKBEsystemsappliedbypreviousresearchersaredependentonsomeCADsoftware,whichmakesthemquiteinconvenientfortheknowledgetobereusedtootherCADsoftware.IndependentknowledgebasedsystemisindependentofCADsoftware；thereforeknowledgecanbereusedfreelyinvariousCADsoftwaresuchasUG,CATIA,Solidworksetc.2GoalofKnowledgeModelingGoalofthisresearchistogetknowledgedrivenparametricmodelbyusingindependentknowledgebasedsystem.Thereforetherelationshipbetweengeometricalandnon-geometricalattributeisbasicconceptfortheframeworkofknowledgemodel.TheGeometricdescriptionisonlyonepieceofinformationaboutthetotalproductmodel6.Fig.2istherelationofgeometricandnon-geometricattribute.Intheparametricmodelingoftheproduct,entitiesareassociatedwithgeometricparametersuchasabooleanprimitive,alineorarcinawireframe,orafilletingoperation.Theseparameterscontrolandplaythevariousgeometricattributessuchasheight,width,length,volumeandareaofthemodel.Theyalsocontrolthelocationsoftheseentitieswithinthemodel.Knowledge-modelDesignparameterNon-geometricGeometricparameterGeometricKnowledgedrivenParameterdrivenFig.2Geometricandnon-geometricattributesPower,weight,material,life,speedratio,loadandmanufacturabilityareincludedinthenon-geometricattributesthatmeantheyaredesignparameter.Geometricandnon-geometricattributesareinterrelated.Forexample,thepitch-linevelocityofthewormisVw=dwnw/12.Geometricpropertiesdw(pitchdiameter)andnon-geometricpropertiesVw(pitch-linevelocity)aredependenttoeachother.TheinputstotheKBEmodelcontaingeometricandnon-geometricattributeswhichcanincludedesignspecifications,designpractices,engineerexpertise,materialpropertiesandstructuralanalysis.Thekey2PHYOWaiLin,XIPing,ZHANGBao-yuan,CHENRui-zhiCADDMresearchcontentofKBEistogetgeometricparametersoutfromnon-geometricparameters.Theoutputisknowledgemodelwhichmeetscustomersdemands.3KnowledgeAcquisitionandRepresentationKnowledgeAcquisitionKAisthetransformationofknowledgefromtheforminwhichitexists(betacitorexplicit)intoformsthatcanbeusedinaknowledge-basedsystem.Theprocessofcollectingdomainknowledgeandtransformingtheknowledgeintoacomputerizedrepresentation:KAincludestheelicitation,collection,analysis,modelingandvalidationofknowledgeforknowledgeengineeringandknowledgemanagementprojects3andinvolvesbreakingdown,grouping,structuring,chainingupandcontrollingtheknowledge.Animportantproblemishowtoextractknowledgefromanexpertandhowtorepresenttheelicitedknowledgeinaknowledge-basedsystem.KAcansolvethatproblembyconsideringthepurposeandfunctionofthedesiredinformation.KBEsystemsuseacombinationofthe“productionrules”and“theobject-orientedknowledgerepresentation”astherepresentationparadigms.Fig.3istheknowledgerepresentationchartofresearchworktocontrolandmodifyknowledgethatneedsacollectionofvariousformsofknowledge,includingMathematicalformulas,Rules,experience,parametricmodel,formandchartformechanicaldesignparametricmodel.Knowledgeimplementationfortypicaldesignmodel,designknowledgecanbecategorizedasfollows:(1)Mathematicalformula:Inthemechanicaldesign,therearemanyareasofmathematicalformsofknowledge.Manydesignpartssuchassize,material,strengthandsoonneedthecomplexmathematicalcalculationsandderivationtogettheirappropriatevalues.Mathematicalformulasincludingexpressions(arithmeticexpressions,logicalexpression,etc.),differentialequationsandintegralequationandsoonthatisusedforthedesignMathematicalCalculationChartTableParametricModelExpertiseRule(IF-THEN)Fig.3Knowledgerepresentationofthetransmissionpartstogetacertainconstraintrelations.Forexample:themathematicalformulaofwormallowablecontactstressissHPHPvNZZ=andstresscyclesequationis160LhNnt=.(2)Classrules:Theknowledge-drivenmodelbehindknowledge-basedengineering(KBE)isbasedonalanguagetailoredforcapturingengineeringrules.Ifthewormheadisequalto1,theestimatedrangeofefficiencyis0.65to0.75；whenthewormheadisequalto2,theefficiencyoftherangeof0.75085；whenthewormheadisgreaterthan2,theeffectiverange0.85.Iftheconditionpartissatisfied,thentheconclusionpartDecember2010TheResearchofIndependentKnowledgeBasedMechanicalDesign3isexecuted.Thesampleofwormgearclassruleexpressionisasfollows:If(worm_z=1)Efficiency=“0.650.75”；If(worm_z=2)Efficiency=“0.750.85”；If(worm_z2)Efficiency=“0.85”；(3)Designtables:Therearemanyengineeringknowledgeofstandardpartsoftenexistsintableform,Fig.4isatableoftherelationshipofmodule,wormdiameterandwormdiameterfactorwhichisusedtodeterminedimensionalfamiliesofproduct.Fig.4TherelationshipofmoduleanddiameterTabledataarediscretebinarymappingthatcanbestoreinarelationaldatabaseaccordingtocertainrulesusingascriptinglanguage.Thisscriptinglanguagerelatedtosyntaxandlanguageinterpretertoexplainthemappingtable,representtousetheform.(4)Expertise:Expertiseplaystheroletofilltheknowledgegapbetweenthedetailstageandtheconceptualstage,assistthedesignerstomakedecision.Forexample,expertisetellswhichworkingtemperaturerangeshouldbemoreeligible,higherthan95orlessthan95.(5)Parametricmodel:Parametricmodelfiles(suchasUG.Prtfile)storethehistoryofproductmodeling,modelingprocesscontainthecarrierofexpertiseandknowledge.Parametricmodelprovidestheknowledgemodelingprocess.Thereforegeometricmodelcanbechangequickly,canbeviewedasaninstanceofaclassofgeometricmodels；Object-orientedmethodcanbeusedtoorganizeandexpressthisknowledge.Forexample,thedesignofthewormgeometricmodelhasseveralgeometricparametersasshowninTable1.Table1WormmodelinggeometryModulemPitchcirclediameterdAddendumcirclediameterd1Toothrootdiameterd2PressureangleaLengthL(6)Chart:Chartisacommonengineeringknowledgeexpresswithtwo-dimensionalcoordinatedsysteminwhichthedataisrepresentedbysymbo