外文翻译--工业机械手夹具的运动合成一种创造性的设计方法 英文版.pdf

257EndEffectsKinematicSynthesisofIndustrialRobotHand/GripperACreativeDesignApproachJayLeeUnitedStatesPostalService,OfficeofAdvancedTechnology,475LEnfantPlazaS.W.,Rm2140,WashingtonDC20260-8120,U.S.A.Thepurposeofthisresearchistosynthesizeindustrialrobothandmechanisms.InvestigationsonDOF(F),complexityandthestructure(Graph)willbepresented.Therefore,akinematicstructuretableofrobothandmechanismscanbegenerated.Theadvantagesofusingthisreferencetableareasfollows:*Identificationofthekinematicstructureofrobothandmechanismsforrobothandstandardization.*Theatlasofgraph(structure)canbeusedtoenumeratenewrobothandmechanisms.*Leadstocreationorinventionofnewrobothandmecha-nismsaccordingtotheseparationofstructureandfunc-tion.Thispaperwillpresentacreativedesignapproachindesigningindustrialrobothand/grippermechanisms.ThisresearchworkwasconductedwhiletheauthorwasatColumbiaUniversity.Keywords:Kinematics,Grippers,Handmechanisms.1.IntroductionRobotichand/gripperistheintegralpartinmostoftheroboticapplications.Marketstudypredictedthattherewillbeover60%roboticap-plicationsinassemblyandmaterialhandling1.Designoftheroboticgrippingmechanismalwaysbecomesthekeyelementfortheentitledproject.Often,verylittletimeisspentinoptimalkine-maticstructure(topology)designintheearlystagesofadesignprocess.Timepressuressometimesforceengineerstorepeattopologiesthathaveworkedinsimilarapplicationsinthepast,ratherthantrytocreatebetterdesigns2.Chen3presentedacompletesurveyofmechanismsusedforgrippersforindustrialrobots.Erdmanetal.2suggestedtechniquesoftypesynthesisbasedongraphtheoryandexpertsystems.Someextensiveworkincreatingdatabaseforrobotichand(grippers)mechanismhasbeendonebytheauthor8.Thispaperwillpresentacreativedesignap-Mr.JayLeeisprogramdirectorinmaterialhandlingresearchfortheOfficeofAdvancedTechnologyofUnitedStatesPostalService.Here-ceivedhisB.S.fromTaiwanandholdsanM.S.degreeinMechanicalEn-gineeringfromtheUniversityofWisconsin-MadisonandanM.S.inIndustrialManagementfromStateUniversityofNewYorkatStonyBrook.HeiscurrentlyadoctoralcandidateinMechanicalEngineeringatUniversityofMaryland.Hehasservedasapart-timelecturerfortheStateUniversityofNewYorkatStonyBrook,forthePolytechnicsUniversityandasadjunctassistantprofessorfortheNewYorkInstituteofTechnology.HeformerlyservedasaprogrammanagerindevelopinghighprecisionandhighspeedrobotictechnologiesforAnoradCorp.(Hauppauge,NY).BeforeAnorad,hewasaNorth-Hollandseniormechanicalengineerandgroupleaderindevelopingvision-guidedrobotictechnologiesforRoboticVisionSystems,Robotics4(1988)257-263Inc.alsoinHauppauge,NewYork.0921-8830/88/$3.50©1988,ElsevierSciencePublishersB.V.(North-Holland)258J.Lee/KinematicSynthesisofIndustrialRobotHandGripperproachindesigningindustrialrobothand/grippermechanism.Thedevelopmentofthekinematicstructureofrobothand/grippermechanismswillalsobepresented.2.OverviewoflnduslrialRobotHand(Gripper)Mechanism131(2)Vacuumandmagnetictype:thisclassin-cludesthreefittedwithsuctioncuporelec-tromagnets.(3)Specialhandandgripper:thisclassconsistsofinflatablefinger,paperpickinggripper.Inthispaper,wewillinvestigatemechanicalfingertypebecausemostindustrialrobothand/grippermechanismsfallintothiscategory.Ingeneral,gripperscanbeclassifiedaccordingtothefollowing:(1)Mechanicalfingertype:Accordingtothenumberoffingersinagripper,wehave(i)2fingertype(ii)3fingertype(iii)multifingertype.Accordingtothenumberofhandsmountedonthewristoftherobotarmwehave(i)singlegripper(ii)dualgripper(iii)multiplegripper(indextype).Accordingtothepartconfiguration,wehave(i)linearmotiongripper(paraller)(ii)angularmotiongripper.Accordingtothekinematicstructure,wehave(i)linkagetype(ii)gearandracktype(iii)camtype(iv)screwtype(v)ropeandpulleytype(MIT/UXAnhand,Hitachihand).2.1.KinematicSynthesisofRobotHand(Gripper)MechanismMechanismcreationbasedontheseparationofstructurefromfunctionwasproposedbyFreuden-stein4-7.Kinematicstructurecanbeenu-meratedinanessentiallysystematic,unbiasedfashionasafunctionofthedegreeoffreedomofthemechanism,thenaturalofthedesiredmotionandaparameterrepresentinganindicationofthecomplexityofthemechanism.Eachstructureob-tainedinthiswaycanthenbesketchedandevaluatedwithrespecttothefunctionalrequire-mentsofthemechanism.Potentiallyacceptablemechanismscanthenbeevaluatedindepthuntilafinaldesignisachieved.Mostmechanismsobeythefollowinggeneral-degree-of-freedomequation:F=)(L-j-1)+EL(1)whereF=degreeoffreedomofmechanismDegreeofKinematicFreedom(f)ElementCommentsHelicalPair(H)12GearPair(G)1_TurningPair(R)ISlidingPair(P)4BallinCylinderFig.1.Commonusedkinematicelementsinrobothand/grippermechanism.J.Lee/KinematicSynthesisofIndustrialRobotHand/GripperTable1Correspondencebetweengraphandmechanism259MechanismLinks(£)Joints(j)JoinedLinksDifferentJointsGroundedElementSameMechanismsDifferentMechanismsIndependentLoopsGraphVertices(v)Edges(e)Edge-connectedverticesLabeledEdgesR=PinJointP=SlidingJointG=GearJointH=HelicalJointFixedLinkIsomorphicGraphsNoniscmorphicGraphsIndependentLoopsSymbolR-pGH®LINDh=mobilitynumber(degreeoffreedominwhichmechanismoperates:),=3forplaneandsphericalmotions；h=6forgeneralthree-dimensionalmotions),L=numberoflinks,j=numberofjoints,andf,=degreeoffreedomofrelativemotionatithjoint.Intermsofthegraphofthemechanism,Equation(1)maybewrittenasr=x(0-e-1)+(2)wherev=numberofverticesofgraph(v=L)ande-numberofedgesofgraph(e=j).LIND=j-L+1(3)LIND=Numberofindependentloopsinthemechanismcombining(1)and(3)El/=r+LIND(4)Forgeartrainsitcanbeshown7thattheseequationsspecializetothefollowing:L=F+1+LINDj=F+2LINDJc=LINDJR-F+LINDwhereJc,JRdenotethenumberofgearpairsandpinjoints.Mostrobothands(grippers)areopen-loopmechanismswhosestructuresaregenerallysimplerthanthoseofclose-loopmechanisms.The166RRRI4pR,R-3R4bcFig.2,Typicalrobothandmechanismandgraph.260J.Lee/KinematicSynthesisofIndustrialRobotHand/GripperNOVe1R#./I5P2P3IR4245oGc"x,G23345R231456KINEMATICROBOTHANDSTRUCTUREMECHANISMRR3R41.iC2i14NOVe556667767KINEMATICSTRUCTURERRR.R413R4R34ROBOTHAND,MECHANISM4Fig.3.Kinematicstructureofrobothandmechanisms.mostcommonjointsinrobothands(grippers)mechanismsaretheturningpairsorpinjoints(R),theslidingpair(P),gearpairs(G),helicalpairsorscrew-and-nut(H)(seeFig.1).Table1showsthecorrespondencebetweengraphsandmechanisms.ThegraphrepresentationofatypicalrobothandmechanismisshowninFig.2.Thedegreeoffreedom(F)andcomplexity(LIND)canbeillustratedbyuseofexamplefromFig.2.Numberoflinks(L)=6Numberofjoints(j)=7Ef=RReRRRR=7X=3(planemechanism)ThereforeF=3(L-j+1)+EL=3(6-7-1)+7=1Thenumberofclosedloopsinthismechanismis(a)LIND=j-L+1=7-6+1=2Thisshouldbeequaltotheresultfromthegraph(b).FromTable1weknowthatthenumberofedges(e)inthegraphisequaltothenumberoflinksinthemechanism.Thenumberofvertices(o)inthegraphisequaltothenumberofjoints(j)inthemechanism.