外文翻译--机器人控制和装配计划相结合的精密机械手.doc

徐州工程学院毕业设计外文翻译学生姓名学院名称机电工程学院专业名称机械设计制造及其自动化指导教师2011年5月27日COMBINATIONOFROBOTCONTROLANDASSEMBLYPLANNINGFORAPRECISIONMANIPULATOORAbstractThispaperresearcheshowtorealizetheautomaticassemblyoperationonatwo-fingerprecisionmanipulator.Amulti-layerassemblysupportsystemisproposed.Atthetask-planninglayer,basedonthecomputer-aideddesign(CAD)model,theassemblysequenceisfirstgenerated,andtheinformationnecessaryforskilldecompositionisalsoderived.Then,theassemblysequenceisdecomposedintorobotskillsattheskill-decompositionlayer.Thesegeneratedskillsaremanagedandexecutedattherobotcontrollayer.Experimentalresultsshowthefeasibilityandefficiencyoftheproposedsystem.KeywordsManipulatorAssemblyplanningSkilldecompositionAutomatedassembly1IntroductionOwingtothemicro-electro-mechanicalsystems(MEMS)techniques,manyproductsarebecomingverysmallandcomplex,suchasmicrophones,micro-opticalcomponents,andmicrofluidicbiomedicaldevices,whichcreatesincreasingneedsfortechnologiesandsystemsfortheautomatedprecisionassemblyofminiatureparts.Manyeffortsaimingatsemi-automatedorautomatedassemblyhavebeenfocusedonmicroassemblytechnologies.However,microassemblytechniquesofhighflexibility,efficiency,andreliabilitystillopentofurtherresearch.Thispaperresearcheshowtorealizetheautomaticassemblyoperationonatwo-fingermicromanipulator.Amulti-layerassemblysupportsystemisproposed.Automaticassemblyisacomplexproblemwhichmayinvolvemanydifferentissues,suchastaskplanning,assemblysequencesgeneration,execution,andcontrol,etc.Itcanbesimplydividedintotwophases；theassemblyplanningandtherobotcontrol.Attheassembly-planningphase,theinformationnecessaryforassemblyoperations,suchastheassemblysequence,isgenerated.Attherobotcontrolphase,therobotisdrivenbasedontheinformationgeneratedattheassembly-planningphase,andtheassemblyoperationsareconducted.Skillprimitivescanworkastheinterfaceofassemblyplanningtorobotcontrol.Severalrobotsystemsbasedonskillprimitiveshavebeenreported.Thebasicideabehindthesesystemsistherobotprogramming.Robotmovementsarespecifiedasskillprimitives,basedonwhichtheassemblytaskismanuallycodedintoprograms.Withtheprograms,therobotiscontrolledtofulfillassemblytasksautomatically.Askill-basedmicromanipulationsystemhasbeendevelopedintheauthorslab,anditcanrealizemanymicromanipulationoperations.Inthesystem,theassemblytaskismanuallydiscomposedintoskillsequencesandcompiledintoafile.Afterimportingthefileintothesystem,thesystemcanautomaticallyexecutetheassemblytask.Thispaperattemptstoexploreauser-friendly,andatthesametimeeasy,sequence-generationmethod,torelievetheburdenofmanuallyprogrammingtheskillsequence.Itisaneffectivemethodtodeterminetheassemblysequencefromgeometriccomputer-aideddesign(CAD)models.Manyapproacheshavebeenproposed.Thispaperappliesasimpleapproachtogeneratetheassemblysequence.Itisnotinvolvedwiththelow-leveldatastructureoftheCADmodel,andcanberealizedwiththeapplicationprogramminginterface(API)functionsthatmanycommercialCADsoftwarepackagesprovide.Intheproposedapproach,arelationsgraphamongdifferentcomponentsisfirstconstructedbyanalyzingtheassemblymodel,andthen,possiblesequencesaresearched,basedonthegraph.Accordingtocertaincriterion,theoptimalsequenceisfinallyobtained.Todecomposetheassemblysequenceintorobotskillsequences,someworkshavebeenreported.InNnajietal.swork,theassemblytaskcommandsareexpandedtomoredetailedcommands,whichcanbeseenasrobotskills,accordingtoapredefinedformat.ThedecompositionapproachofMosemannandWahlisbasedontheanalysisofhyperarcsofAND/ORgraphsrepresentingtheautomaticallygeneratedassemblyplans.Thispaperproposesamethodtoguidetheskilldecomposition.Theassemblyprocessesofpartsaregroupedintodifferentphases,andpartsareatdifferentstates.Specificworkflowspushforwardpartsfromonestatetoanotherstate.Eachworkflowisassociatedwithaskillgenerator.Accordingtothedifferentstartstateandtargetstateoftheworkflow,theskillgeneratorcreatesaseriesofskillsthatcanpromotetheparttoitstargetstate.Thehierarchyofthesystemproposedhere,theassemblyinformationonhowtoassembleaproductistransferredtotherobotthroughmultiplelayers.Thetoplayerisfortheassembly-taskplanning.TheinformationneededforthetaskplanningandskillgenerationareextractedfromtheCADmodelandaresavedinthedatabase.BasedontheCADmodel,theassemblytasksequencesaregenerated.Attheskill-decompositionlayer,tasksaredecomposedintoskillsequences.Thegeneratedskillsaremanagedandexecutedattherobotcontrollayer.2TaskplanningSkillsarenotuseddirectlyattheassembly-planningphase.Instead,theconceptofataskisused.Ataskcanfulfillaseriesofassemblyoperations,forexample,fromlocatingapart,throughmovingthepart,tofixingitwithanotherpart.Inotherwords,onetaskincludesmanyfunctionsthatmaybefulfilledbyseveraldifferentskills.Ataskisdefinedas:T=（BasePart；AssemblyPart；Operation）Base_PartandAssembly_Partaretwopartsthatareassembledtogether.Base_Partisfixedontheworktable,whileAssembly_Partishandledbyrobotsend-effectorandassembledontotheBase_Part.OperationdescribeshowtheAssembly_PartisassembledwiththeBase_Part；OperationInsertion_T,screw_T,align_T,.Thestructureofmicropartsisusuallyuncomplicated,andtheycanbemodeledbytheconstructivesolidgeometry(CSG)method.Currently,manycommercialCADsoftwarepackagescansupport3DCSGmodeling.Theassemblymodelisrepresentedasanobjectthatconsistsoftwopartswithcertainassemblyrelationsthatdefinehowthepartsaretobeassembled.IntheCADmodel,therelationsaredefinedbygeometricconstraints.ThegeometricinformationcannotbeuseddirectlytoguidetheassemblyoperationwehavetoderivetheinformationnecessaryforassemblyoperationsfromtheCADmodel.Throughsearchingtheassemblytreeandgeometricrelations(matesrelations)definedintheassemblysCADmodel,wecangeneratearelationgraphamongparts,forexample,Inthegraph,thenodesrepresenttheparts.Ifnodesareconnected,itmeansthatthereareassemblyrelationsamongtheseconnectednodes(parts).2.1MatingdirectionInCSG,therelationsoftwoparts,geometricconstraints,arefinallyrepresentedasrelationsbetweenplanesandlines,suchascollinear,coplanar,tangential,perpendicular,etc.Forexample,ashaftisassembledinahole.Theassemblyrelationsbetweenthetwopartsmayconsistofsuchtwoconstraintsascolli