外文翻译新创造的轮式督导机制移动机器人.doc
外文文献翻译(2008届)NewSteeringMechanismforWheeledMobileRobots新创造的轮式督导机制移动机器人学生姓名郑正锐学号04081133院系工学院机电系专业机械设计制造及其自动化指导教师完成日期NewSteeringMechanismforWheeledMobileRobotsSiaibeMarieBernard,FUYi-li,XUHe,MAYu-lin(SchoolofMechanicalandElectricalEngineering,CenterofAdvancedManufacturingTechnology,HarbinInstituteofTechnologyHarbin150001,China,Email:sidibebernardyaho.Fr)Abstract:AnewcastorwheelmechanismforOmni-directionalmobileplatformispresented.Amotionoftranslationistransformedintoarotationtosteerthewheelwiththehelpofahelicalpathfitsintoatranslationjointandthreerollerswhoseaxesareconnectedtothedrivingshaftofthewheel.Whenthepathmovesintranslationitactsontherollersforsteering.Thepath-rollerfrictiontransmission.Thewheelkinematicsandthemaneuverabilityhavebeenanalyzed.Keywords:castorwheel;helicalpath;friction;roller;maneuverability;mobilityCLCnumber:TP24Documentcode:AArticleID:l0o5-9l13(2007)02-0184-05Mobileplatformhasattractedvariousresearchesinroboticapplicationssuchaswheelchair,car-like-robotetc.DifferentcategoriesofOmni-directionalmobileplatformshavebeenpresentedsignificantlyoverthelast20years.Theirmechanicalstructuresaremainlydifferentiatedandcharacterizedbythewheelechanisms.whichdeterminetheirmobility【1】.Ithasbeenshownthatonlyrobotsequippedwiththreecastorwheelsorthreeuniversalwheelshavefu儿mobility(homonymicandmni-directional)【5】.Theuniversalwheelspresentseveraldrawbackssuchaslowloadcapacity-Periodicalbumpleadingtoavibration【8】.Theirmechanismisusuallycomplex,withmanypartsincreasingtheweightofthemobileplatform.Thethreecastor-Wheeledmobilerobotmaindrawbacksisthatitneedsatleastfouractuators(threeforsteeringandatleastonefordrive).Someexamplesexistwithsixactuators,threedrivingandthreesteeringactuators.Thisphenomenonleadstosomesingularitiesincontrol.Butithastheadvantageofcarryingimportantload9.Uptonownewresearchesaregoingoncastorwheeledmobilerobot【2.3】,andmostofmobilerobotsformanipulationhaveonlyconventionalwheel9,Theinterestofourresearchconsistsofadesignofnewtypeofcastorwheelmechanismwithaconnectionofelementaryjoints(spin,linearandscrewjoints).Theinterestofourworkistheimprovementofthemaneuverability.ForthatwehaveshowninSection4thatanelementarylineardisplacementofthejointcanproduceanimportantsteeringangleofthewheelbecausethesteeringangleofourmechanismdependsonthelineardisplacementofajoint.ThekinematicsisgiveninSection2.1WheelArchitecture1.1DescriptionThecomputermodelisrepresentedinFigs.13representthekinematicalchainofthewheelmechanism.Ithas3rollers(Fig.2)abletorotatefreelyabouttheiraxis.Eachofthemhasafreerevolutejointwithashaft.Thethreeshaftsarebuiltintoeachotherandfittothewheelshaftandtherevolutejoint4(Figs.1and3)Sotheensembleofthisconnectionconstitutesthewheellink(wheelsuspension)whichcanturnabouttheverticalaxepassingtroughthecentersofjoints1,3and4(Fig.3).Theshaftdividedintotwodifferentforms:cylindricalformatonesideandprismaticatanotherone(Fig.1).Atthedownsideisacylinderformingwiththewheellinkarevolutejoint(joint4)andtheuppersideisprismaticbuiltintheplatformandformingwiththecylinderofthehelicalpathatranslationjoint1.Theaimofthelatestcitedistoprovideatranslationmotiontothehelicalpathrea1izedaroundacylinder(Fig.1,partwithgoldcolor)。1.2KinematicsDescriptionThekinematicsrepresentationofthemechanismisinFig.3.Infact.thehelicalpathandrollersconnectioncanbeconsideredasascrewjoint.Thepathisascrewconstrainedinrotationaboutverticalaxisbyjointlandtherollersconsistofanutconstrainedintranslationaboutthesameaxlebyjoint4.Joint1isactuatedintranslation.Whenitmovesthepathactsontherollers.Attheirturn,animatingbyarotationabouttheverticalaxe.Theyreactonthewheellinkandfinallyonthewheel.Theeccentricityeandtheheighthremainconstantwhateverthepostureoftheplatform.Theuseofrollersrollingwithoutslippinginsidethepathisimportanttoavoidcoulombfrictioneveniftheymakethemechanismlittlebulky.2Path-rollerFrictionLetusconsideracylinderinacoordinatesystem(oX,Y,z)andfreeofrotationaboutitsaxle(Fig.4(a).ThecylinderanditsaxlealefreetorotateaboutandaverticalaxledistantofRfromthewheel.Aninclinedplanwithangle6isincontactwiththecylinder.Whentheplantranslateswithrespecttoaxis.Thecontactline(cylinderplan)moveswithrespecttoaxisYandthecylinderrotatesofangleabouttheverticalaxle.Thisanglecorrespondstotherotationangleofthecontactline.