中英文文献翻译一个机器人结构设计及运动学Word格式.docx

中英文文献翻译一个机器人结构设计及运动学Word格式.docx

《中英文文献翻译一个机器人结构设计及运动学Word格式.docx》由会员分享，可在线阅读，更多相关《中英文文献翻译一个机器人结构设计及运动学Word格式.docx（24页珍藏版）》请在冰豆网上搜索。

thearmwiththefirstthreejointsformajorpositioningandthewristwiththelastthreejointsformajororienting.Ifweconsidertheconsecutivelinkstobeparallelorperpendicular,only12armandtwowristconfigurationsarepotentiallyusefulanddifferentforrobotmanipulatormechanicaldesign.Thiskindofsimplificationcanleadtoageneralalgorithmofinversekinematicsforthecorrespondingconfigurationofdifferentcombinationsofarmandwrist.Theapproachesforcalculatingtheinversekinematicsofarobotmanipulatorareveryefficientandeasy.Theapproachesforcalculatingtheinversekinematicsofarobotmanipulatorareveryefficientandeasy.

1.INTROUCTION

Arobotmanipulatorconsistsofanumberoflinksconnectedtogetherbyjoints.Inrobotmanipulatordesign,theselectionofthekinematicchainoftherobotmanipulatorisoneofthemostimportantdecisionsinthemechanicalandcontrollerdesignprocess.

Inordertopositionandorienttheendeffectoroftherobotmanipulatorarbitrarily,sixdegreesoffreedomarerequired:

threedegreesoffreedomforpositionandthreedegreesoffreedomfororient-ation.Eachmanipulatorjointcanprovideonedegreeoffreedom,andthusamanipulatormusthaveaminimumofsixjointsifitistoprovidesixorthogonaldegreesoffreedominpositionandorientation.

Theconstructionofmanipulatorsdependsonthedifferentcombinationofjoints.Thenumberofposs-iblevariationsofanindustrialrobotstructurecanbedeterminedasfollows:

V=6

where

V=numberofvariations.

DF=numberofdegreesoffreedom

Theseconsiderationsshowthataverylargenumberofdifferentchainscanbebuilt,forexamplesixaxis46,656chainsarepossible.6However,alargenumberisnotappropriateforkinematicreasons.

Wemaydividethesixdegreesoffreedomofarobotmanipulatorintotwoparts:

thearmwhichconsistsofthefirstthreejointsandrelatedlinks;

andthewristwhichconsistsofthelastthreejointsandrelatedlinks.Thenthevariationsofkinematicchainswillbetremendouslyreduced.Lienhasdevelopedtheconstructionsofarmandwrist,i.e.20differentconstructionsforthearmandeightforthewrist.2

Inthispaper,weabbreviatethe20differentarmsinto12kindsofarmswhichareusefulanddifferent.Weconcludethatfivekindsofarmsandtwokindsofwristsarebasicconstructionsforcommercialindus-trialrobotmanipulators.Thiskindofsimplificationmayleadtoageneralalgorithmofinversekinema-ticsforthecorrespondingconfigurationofdifferentcombinationsofarmandwrist.

2.STRUCTUREDESIGNOFROBOTMANIPULATORS

Inthispaper,foroptimumworkspaceandsim-plicity,weassumethat:

（a）Arobotwithsixdegreesoffreedommaybeseparatedintotwoparts:

thelinkageconsistingofthefirstthreejointsandrelatedlinksiscalledthearm;

thelinkageoftheremainingjointsandrelatedlinksiscalledthewrist.

（b）Twolinksareconnectedbyalowerpairjoint.Onlyrevoluteandlinearjointsareusedinrobotmanipulators.

（c）Theaxesofjointsareeitherperpendicularor

Accordingtotheauthors'

knowledge,thisassumptionissuitableformostcommerciallyusedindustrialrobotmanipulators.Wecanconsiderthestructureofarmandwristseparately.

2.1.Thestructureofthearmofrobotmanipulator

（a）Graphicalrepresentation.Todrawarobotinsidevieworinperspectiveiscomplicatedanddoesnotgiveaclearpictureofhowthevarioussegmentsmoveinrelationtoeachother.Todrawarobotinaplanesketcheddiagramistoosimpleanddoesnotgiveaclearconstructionpicture.Wecompromisethisprobleminasimplethree-dimensionaldiagramtoexpresstheconstructionandmovementsofarobotmanipulator.AtypicalformofrepresentationfordifferentarticulationsisshowninTable1.

（b）Combinationofjoints.WeuseRtorepresentarevolutejointandLtorepresentalinearjoint.Differentcombinationsofjointscanbeobtainedasfollows:

Accordingtothedifferentcombinationswiththeparallelorperpendicularaxes,eachpreviouscombin-ationhasfourkindsofsub-combination.Thus,32combinationscanbearrivedat:

Ifthesecondjointisalinearjointandboththeotherjointsareperpendiculartoit,twochoicesinrelationtothefirstandthethirdjointsareconsideredparal-lelorperpendicular.

Inall,thereare36possiblecombinationsofasimplethree-jointarm.

Nineof36possiblecombinationsdegenerateintooneortwodegreesoffreedom.

Sevenoftheremainderareplanarmechanisms.Thus,thereare20possiblespatialsimplearms.

LetusconsiderR1[1L2IL3inwhichthefirstjointpermitsrotationabouttheverticalaxis,thesecondjointisaverticallinearjoint（i.e.paralleltothefirst）,andthethirdjointisahorizontallinearjoint（i.e.perpendiculartothesecond）.Thisarmdefinesatypicalcylindricalrobot.Changingthesequentialorderofthejointssothateither（a）theverticallinearjointprecedestherotaryjoint,or（b）theverticallinearjointfollowsthehorizontalone,willresultinnochangeinthemotionofthearm.Inthiscasetherearetwolinkageswhichareboth"

equivalent"

tothestandardcylindricallinkage.Inallsuchcaseswheretwoormoreequivalentlinkagesexist,therepresentativeofthegroupwillbetheoneinwhichthelinearjointthatisparalleltoarotaryjointisinthemiddle（jointNo.2）.Countingonlyonelinkagetorepresentthegroupofequivalentswilleliminateeightofthe20combinations.Theremaining12categoriesoflinksareusefulanddif-ferentshowninFig.1.WegetthesameresultsasinRef.4.

（c）Fivebasictypesofmanipulatorarm.Althoughthereare12usefulanddifferentarm-configurationswhichcanbeusedinthedesignofarobotman-ipulatorarm,inpracticeonlysomeofthemarepracticalandcommonlyused.Wefindthatmostcommerciallyavailableindustrialrobotscanbebrokendownintoonlyfivegroupsaccordingtothe.

characteristicsoftheirarmmotionandgeometricalappearance.ThefivegroupscanbedefinedasfollowsandareshowninFig.6.

1.Cartesian（LILIL）

2.Cylindrical（RIIL1L）

3.Spherical（RIRIL）

4.Revolute（RIRIIR）

5.Doublecylindrical（LIIRIIR）.

2.2.Thestructureofamanipulatorwrist

（a）Jointtype.Wehaveusedthefirstthreejoints,i.e.thearmoftherobotmanipulator,tocompletethemajortaskofpositioning.Thenweusethelastthreejointstoprovidethethreedegreesoffreedomoforientationandrefertotherelatedlinkagesasthewrist.

Thewristofacompletemanipulatormustcontainthreerevolutejoints,sincetheorientationofarigidbodyhasthreedegreesoffreedom,forexamplefirstrotationabouttheXaxis,thenrotationabouttheyaxis,andfinallyrotationaboutthezaxis.

（b）Combinationorjointsandlinks.Becausetheorientationofawristwhichonlyhasthreerotationaljointsissimplest,itscombinationismuchsimpFromthecombinationRRR,weknowthatonlyoneofthefourconfigurationscanbeusedforcom-pletingtheorientationofrobotwrist.RIIRIIRisaplanarmechanism.R1RIIRandRIIR1Rcannotexpressthreedegreesoffreedomintheorientationoftherobotwrist.SoonlytheR1R1Rconstruc-tioncanbeusedtocompletetheorientationtask.

Ifwehaveadifferentsequenceofx,y,zaxes,ofcoursewecangetmanykindsofwristconfiguration.Butmanyofthemare"

.Weonlycon-sidertherelationshipbetweenthefirstandthethirdjoint:

parallelandperpendicular.Twodifferentcombinationscanbearrivedat,i.e.theEulerangleandroll-pitch-yawangleexpressionsthatareshowninFig.2.Thesequenceofx,y,zaxesdoes,however,haveaninfluenceonthecomplexityoftheinversekinematicsolution.

2.3.Typicalrobotmanipulatorstructure

Wecanusefivecategoriesofarmconfigurationandtwokindsofwristconfigurationtocombine10differentkindsofrobotmanipulatorswiththesixdegreesoffreedomwhichexistinindustrialpractice.Ofcourse,wecanalsoconsidertheothersevenoutof12armcategorieswithoneoutoftwowristcategoriestobuildanewrobotmanipulator.Butmostofthemhavenotappearedinindustrialprac-ticeyet.

3.SOLUTIONFORINVERSEKINEMATICSOFROBOTMANIPULATOR

3.1.GeneralprinciplesTofindtheinversekinematicequationsofarobotmanipulatoratfirstappearstobeadifficulttask.Butwhenthemanipulatorisseparatedintotwoparts,itbecomesrelativelysimple.Therelationshipbetweenthepositionandorien-tationofmanipulatorlinksconnectedtogetherbyrotationaljointsshowninFig.3,canbedescribedby

Where

0iistheithjointvariable;

diistheithjointoffset;

aiistheithlinklength;

and

aiistheithlinktwistangle.

Thepositionandorientationoftheendeffectoroftherobotmanipulator°

Tisthematricesproduct.3,

T=AIA2A3A4AsA6.

（2）

Bytheassociativelawtheproductofmatricescanberegroupedintotwosubsetswhichrepresentthearmandwristrespectively

And

Thesuperscriptsdesignatethereferenceframe;

arepresentsthetipofthearm;

andwrepresentsthetipofwrist,i.e.thecenteroftheendeffectorofthemanipulator.°

Tgivenfortheendeffectorcanbewrittenasa4x4homogeneousmatrixcomposedofaorienta-tionsubmatrixRandapositionvectorp5.6

WecanobtainthevectorOaPdirectlyusingavectoranalysismethod.Thedetailwillbementionedinthenextsection.

fromEq.（4）,

Wecanget01,02,03,thefirstthreejointvariablesfromthesolutionofthefollowingequation: