54883《機(jī)械原理（英語）（第2版）》基本課件Chapter 10 Spatial Mechanisms and Robotic Mechanisms

Chapter10SpatialMechanismsandRoboticMechanisms1.SpatialKinematicalPairs(1)ClassⅠkinematicpairsAsphereisplacedonanevenplaneshowninFig10-1a.

(2)ClassⅡkinematicpairsEachclassⅡkinematicpairofferstwoconstraintsandhasfourdegreesoffreedom.Fig.10-1bshowsacylinderplanepairwhichconstrainsthetranslationalmotionalongthezaxisandtherotationalmotionaboutthexaxis.

10.1IntroductionofSpatialMechanismsFig.10-1Spatialkinematicpairs1(空間運(yùn)動副1)(3)ClassⅢkinematicpairsEachclassⅢkinematicpairoffersthreeconstraintsandthreedegreesoffreedom.Fig.10-2ashowsasphericalpairwhichconstrainstranslationalmotionsalongthex,yandzaxeswhileoffersthreerotationalmotionsabouttheseaxes,denotedasS.Fig.10-2bshowsthesketchdiagramofthesphericalpair.Thispairiswidelyusedinspatialmechanisms.

Fig.10-2Spatialkinematicpairs2(空間運(yùn)動副2)(4)ClassⅣkinematicpairsEveryclassⅣkinematicpairoffersfourconstraintsandtwodegreesoffreedom.Fig.10-3ashowsaspherepinpairwhichhasonlytworotationaldegreesoffreedombecauseoftheconstraintofthepin.ThespherepinpairisdenotedasS′.Fig.10-3bisitssketchdiagram.Fig10-cshowsacylinderpairwhichpermitsthetranslationalmotionalongitsaxesandtherotationalmotionaboutthesameaxis.Fig10-dshowsitssketchdiagramanddenotedasC.

Fig.10-3Spatialkinematicpairs3(空間運(yùn)動副3)(5)ClassⅤkinematicpairsAclassⅤkinematicpairoffersfiveconstraintsandonedegreeoffreedom.Fig10-4ashowsarevolutepairwhichhasonlyonerotationaldegreeoffreedom.Fig10-4bisitssketch,denotedasR.Fig10-4cshowsaprismaticpairwhichhasonlyonedegreeoffreedomthatpermitsittoexecutetranslationalmotionalongtheaxes,denotedasP.Fig.10-4dshowsitssketch.Fig10-4eshowsahelicalpairwhichpermitsthetranslationalmotionalongitsaxisandtherotationalmotionaboutthesameaxis.Fig.10-4Spacialkinematicpairs4(空間運(yùn)動副4)2.DegreesofFreedomofSpatialMechanismsWeassumethatthereareclassⅠkinematicpairsofp1,sotheycanofferconstraintsof1p1.Similarly,classⅡkinematicpairsofp2canofferconstraintsof2p2,classⅢkinematicpairsofp3canofferconstraintsof3p3,classⅣkinematicpairsofp4canofferconstraintsof4p4,andclassⅤkinematicpairsofp5canofferconstraintsof5p5.Therefore,thedegreeoffreedomofspatialmechanismscanbewrittenasfollows:Fig.10-5Aircraftundercarriage(飛機(jī)起落架)3.ClassificationofSpatialMechanism(1)ExpressionofspatialmechanismTheplanarmechanismsarenamedbytheirkinematicalcharacters,suchascrankrockermechanism,slidercrankmechanism,doublecrankmechanismandsoon.Generally,wenamethespatialmechanismsbythenamesoftheirkinematicpairs.Thefirstalphabetisthesymbolofthekinematicpairwhichconnectsthedrivinglinkandframe,thenwecanarrangethesymbolsofotherkinematicpairsorderly.Fig.10-5showsanaircraftundercarriagewhichcanbenamedasthespatialmechanismofSPSR.

(2)ClassificationofspatialmechanismsThespatialmechanismsareclassifiedasclosedchainmechanismsandopenchainmechanisms,accordingtothekinematicalchainisclosedoropen.Theopenchainmechanismsarewidelyappliedtotherobotfield.Fig.10-6ashowsaRSSRmechanism,inwhichlinks1,2,3andthefixedlink4areconnectedbyrevolutepairsandsphericalpairs.Itisaclosedspatialmechanism.Fig.10-6bshowsa4Ropenchainmechanisminwhichthefixedlink1andlinks2,3,4,5areconnectedbyfourrevolutepairs,anditisanunclosedspatialmechanism.Fig.10-6Classificationofspatialmechanisms(空間機(jī)構(gòu)分類)Example10-1Fig.10-7ashowsaR3Cmechanism.Calculatethedegreesoffreedomofthemechanism.Fig.10-7D.O.Fofspatialmechanisms(空間機(jī)構(gòu)的自由度)4.DegreesofFreedomofSpatialMechanismsExample10-2Fig.10-7bshowsaRSSRmechanism.Calculatethedegreesoffreedomofthismechanism.Example10-3Fig.10-8showsaopenlinkrobotmechanism.Calculatethedegreesoffreedomofthismechanism.Fig.10-8Openlinkrobotmechanism

(開鏈機(jī)器人機(jī)構(gòu))1.TandemRobotMechanismsFig.10-9Tandemrobotmechanism(串聯(lián)機(jī)器人機(jī)構(gòu))

1—Wristjoint(腕關(guān)節(jié))2—Elbowjoint(肘關(guān)節(jié))3—Shoulderjoint(肩關(guān)節(jié))

4—Waistjoint(腰關(guān)節(jié))5—Base(底座)10.2IntroductionofRoboticMechanisms

Fig.10-9ashowsa3Rrobot,whichconsistsofthreerevolutepairsandthreelinks.Atandemrobotusuallyhasfiveparts;theyarebase,waist,shoulder,elbowandwrist.Accordingly,therearefourkinematicpairswhichcontainwaist,shoulder,elbowandwristjoint.Fig.10-9bisthesketchdiagram.2.ParallelRobotMechanismsFig.10-10Parallelrobotmechanisms(并聯(lián)機(jī)器人機(jī)構(gòu))Fig.10-10ashowsaplanarparallelmechanisminwhichthreeinputlinksdrivethemovingplatform1toperformdesiredmotion.Thisiscalled3RRRplanarparallelmechanism,andithasawidelyuseinmicromechanisms.Fig.10-10bshowsaspatialparallelrobotmechanism.Itiscalled3RPSparallelrobotmechanism.Thereisonedegreeoffreedomineverybranch.Comparedwiththetandemrobot,thisparallelrobothasabetterrigiditybutitsworkspaceissmaller.3.ApplicationsofRobotictMechanisms

Robotsaretypicalelectromechanicalproductswhichhaveaver