外文翻译--机器人控制和装配计划相结合的精密机械手.doc -- 5 元

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COMBINATIONOFROBOTCONTROLANDASSEMBLYPLANNINGFORAPRECISIONMANIPULATOORAbstractThispaperresearcheshowtorealizetheautomaticassemblyoperationonatwofingerprecisionmanipulator.Amultilayerassemblysupportsystemisproposed.Atthetaskplanninglayer,basedonthecomputeraideddesignCADmodel,theassemblysequenceisfirstgenerated,andtheinformationnecessaryforskilldecompositionisalsoderived.Then,theassemblysequenceisdecomposedintorobotskillsattheskilldecompositionlayer.Thesegeneratedskillsaremanagedandexecutedattherobotcontrollayer.Experimentalresultsshowthefeasibilityandefficiencyoftheproposedsystem.KeywordsManipulatorAssemblyplanningSkilldecompositionAutomatedassembly1IntroductionOwingtothemicroelectromechanicalsystemsMEMStechniques,manyproductsarebecomingverysmallandcomplex,suchasmicrophones,microopticalcomponents,andmicrofluidicbiomedicaldevices,whichcreatesincreasingneedsfortechnologiesandsystemsfortheautomatedprecisionassemblyofminiatureparts.Manyeffortsaimingatsemiautomatedorautomatedassemblyhavebeenfocusedonmicroassemblytechnologies.However,microassemblytechniquesofhighflexibility,efficiency,andreliabilitystillopentofurtherresearch.Thispaperresearcheshowtorealizetheautomaticassemblyoperationonatwofingermicromanipulator.Amultilayerassemblysupportsystemisproposed.Automaticassemblyisacomplexproblemwhichmayinvolvemanydifferentissues,suchastaskplanning,assemblysequencesgeneration,execution,andcontrol,etc.Itcanbesimplydividedintotwophasestheassemblyplanningandtherobotcontrol.Attheassemblyplanningphase,theinformationnecessaryforassemblyoperations,suchastheassemblysequence,isgenerated.Attherobotcontrolphase,therobotisdrivenbasedontheinformationgeneratedattheassemblyplanningphase,andtheassemblyoperationsareconducted.Skillprimitivescanworkastheinterfaceofassemblyplanningtorobotcontrol.Severalrobotsystemsbasedonskillprimitiveshavebeenreported.Thebasicideabehindthesesystemsistherobotprogramming.Robotmovementsarespecifiedasskillprimitives,basedonwhichtheassemblytaskismanuallycodedintoprograms.Withtheprograms,therobotiscontrolledtofulfillassemblytasksautomatically.Askillbasedmicromanipulationsystemhasbeendevelopedintheauthorslab,anditcanrealizemanymicromanipulationoperations.Inthesystem,theassemblytaskismanuallydiscomposedintoskillsequencesandcompiledintoafile.Afterimportingthefileintothesystem,thesystemcanautomaticallyexecutetheassemblytask.Thispaperattemptstoexploreauserfriendly,andatthesametimeeasy,sequencegenerationmethod,torelievetheburdenofmanuallyprogrammingtheskillsequence.ItisaneffectivemethodtodeterminetheassemblysequencefromgeometriccomputeraideddesignCADmodels.Manyapproacheshavebeenproposed.Thispaperappliesasimpleapproachtogeneratetheassemblysequence.ItisnotinvolvedwiththelowleveldatastructureoftheCADmodel,andcanberealizedwiththeapplicationprogramminginterfaceAPIfunctionsthatmanycommercialCADsoftwarepackagesprovide.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.Thetoplayerisfortheassemblytaskplanning.TheinformationneededforthetaskplanningandskillgenerationareextractedfromtheCADmodelandaresavedinthedatabase.BasedontheCADmodel,theassemblytasksequencesaregenerated.Attheskilldecompositionlayer,tasksaredecomposedintoskillsequences.Thegeneratedskillsaremanagedandexecutedattherobotcontrollayer.2TaskplanningSkillsarenotuseddirectlyattheassemblyplanningphase.Instead,theconceptofataskisused.Ataskcanfulfillaseriesofassemblyoperations,forexample,fromlocatingapart,throughmovingthepart,tofixingitwithanotherpart.Inotherwords,onetaskincludesmanyfunctionsthatmaybefulfilledbyseveraldifferentskills.AtaskisdefinedasT（BasePartAssemblyPartOperation）Base_PartandAssembly_Partaretwopartsthatareassembledtogether.Base_Partisfixedontheworktable,whileAssembly_PartishandledbyrobotsendeffectorandassembledontotheBase_Part.OperationdescribeshowtheAssembly_PartisassembledwiththeBase_PartOperation∈{Insertion_T,screw_T,align_T,...}.Thestructureofmicropartsisusuallyuncomplicated,andtheycanbemodeledbytheconstructivesolidgeometryCSGmethod.Currently,manycommercialCADsoftwarepackagescansupport3DCSGmodeling.Theassemblymodelisrepresentedasanobjectthatconsistsoftwopartswithcertainassemblyrelationsthatdefinehowthepartsaretobeassembled.IntheCADmodel,therelationsaredefinedbygeometricconstraints.ThegeometricinformationcannotbeuseddirectlytoguidetheassemblyoperationwehavetoderivetheinformationnecessaryforassemblyoperationsfromtheCADmodel.ThroughsearchingtheassemblytreeandgeometricrelationsmatesrelationsdefinedintheassemblysCADmodel,wecangeneratearelationgraphamongparts,forexample,Inthegraph,thenodesrepresenttheparts.Ifnodesareconnected,itmeansthatthereareassemblyrelationsamongtheseconnectednodesparts.2.1MatingdirectionInCSG,therelationsoftwoparts,geometricconstraints,arefinallyrepresentedasrelationsbetweenplanesandlines,suchascollinear,coplanar,tangential,perpendicular,etc.Forexample,ashaftisassembledinahole.TheassemblyrelationsbetweenthetwopartsmayconsistofsuchtwoconstraintsascollinearbetweenthecenterlineofshaftLc_shaftandthecenterlineofholeLc_holeandcoplanarbetweentheplaneP_ShaftandtheplaneP_Hole.Thematingdirectionisakeyissueforanassemblyoperation.ThispaperappliesthefollowingapproachtocomputethepossiblematingdirectionbasedonthegeometricconstraintstheshaftinholeoperationofFig.3istakenasanexample1.Forapartintherelationgraph,calculateitsremainingdegreesoffreedom,alsocalleddegreesofseparation,ofeachgeometricconstraint.Forthecoplanarconstraint,theremainingdegreesoffreedomarezRotyxR,,1.Forthecollinearconstraint,theremainingdegreesoffreedomarezRotzR,2.1Rand2Rcanalsoberepresentedas1,0,0,0,1,11Rand1,0,0,1,0,02R.Here,1meansthatthereisadegreeof