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MoredetailsandexamplesonrobotarmsandkinematicsDenavit-HartenbergNotationINTRODUCTIONForwardKinematics:todetermin
ewheretherobot’shandis?(Ifalljointvariablesareknown)InverseKinematics:tocalculatewhateachjointvariableis?(Ifwedesirethatthehan
dbelocatedataparticularpoint)DirectKinematicsDirectKinematicswithnomatricesWhereismyhand?DirectKinematics:HERE!DirectKinematics
•Positionoftipin(x,y)coordinatesDirectKinematicsAlgorithm1)Drawsketch2)Numberlinks.Base=0,Lastlink=n3)Identifyandnumberrobotjoints4)Drawax
isZiforjointi5)Determinejointlengthai-1betweenZi-1andZi6)DrawaxisXi-17)Determinejointtwisti-1measuredaroun
dXi-18)Determinethejointoffsetdi9)DeterminejointangleiaroundZi10+11)WritelinktransformationandconcatenateOftens
ufficientfor2DKinematicProblemsforManipulation•Reliablypositionthetip-gofromonepositiontoanotherposition•D
on’thitanything,avoidobstacles•Makesmoothmotions–atreasonablespeedsand–atreasonableaccelerations•Adjusttochangingconditions-–i.
e.whensomethingispickeduprespondtothechangeinweightROBOTSASMECHANISMsRobotKinematics:ROBOTSASMECHANISMFig.2.1Aone-
degree-of-freedomclosed-loopfour-barmechanismMultipletyperobothavemultipleDOF.(3Dimensional,openloop,chainmechanisms)Fig.2.2
(a)Closed-loopversus(b)open-loopmechanismChapter2RobotKinematics:PositionAnalysisFig.2.3Representationofapointinspa
ceApointPinspace:3coordinatesrelativetoareferenceframe^^^kcjbiaPzyxRepresentationofaPointinSpaceC
hapter2RobotKinematics:PositionAnalysisFig.2.4RepresentationofavectorinspaceAVectorPinspace:3coordinatesofitstailandofitshe
ad^^^__kcjbiaPzyxwzyxP__RepresentationofaVectorinSpaceChapter2RobotKinematics:PositionAnalysisFig.2.5Representationofaframeattheori
ginofthereferenceframeEachUnitVectorismutuallyperpendicular.:normal,orientation,approachvectorzzzyyy
xxxaonaonaonFRepresentationofaFrameattheOriginofaFixed-ReferenceFrameChapter2RobotKinematics:PositionAnalysisFig.2.6
RepresentationofaframeinaframeEachUnitVectorismutuallyperpendicular.:normal,orientation,approachvector
1000zzzzyyyyxxxxPaonPaonPaonFRepresentationofaFrameinaFixedReferenceFrameThesameaslastslideChapter2RobotKinematics:PositionAnalysisFig.2.8Rep
resentationofanobjectinspaceAnobjectcanberepresentedinspacebyattachingaframetoitandrepresentingtheframeinspace.100
0zzzzyyyyxxxxobjectPaonPaonPaonFRepresentationofaRigidBodyChapter2RobotKinematics:PositionAnalysisAtransformationmatricesmust
beinsquareform.•Itismucheasiertocalculatetheinverseofsquarematrices.•Tomultiplytwomatrices,theirdimensionsmustmatch.1000zzzzy
yyyxxxxPaonPaonPaonFHOMOGENEOUSTRANSFORMATIONMATRICESRepresentationofTransformationsofrigidobjectsin3D
spaceChapter2RobotKinematics:PositionAnalysisFig.2.9RepresentationofanpuretranslationinspaceAtransformationisdefinedasmakingamovementinspac
e.•Apuretranslation.•Apurerotationaboutanaxis.•Acombinationoftranslationorrotations.1000100010001zyxdddTRepresentationofaPureTransl
ationidentitySamevalueaChapter2RobotKinematics:PositionAnalysisFig.2.10Coordinatesofapointinarotatingframebeforeandafterrotationaroundaxisx.Ass
umption:Theframeisattheoriginofthereferenceframeandparalleltoit.Fig.2.11Coordinatesofapointrelativetothereferenceframeandrotatingframeasview
edfromthex-axis.RepresentationofaPureRotationaboutanAxisProjectionsasseenfromxaxisx,y,zn,o,aFig.2.13
EffectsofthreesuccessivetransformationsAnumberofsuccessivetranslationsandrotations….RepresentationofCombin
edTransformationsOrderisimportantx,y,zn,o,anioiaiT1T2T3Fig.2.14Changingtheorderoftransformationswillchangethefinal
resultOrderofTransformationsisimportantx,y,zn,o,atranslationChapter2RobotKinematics:PositionAnalysisFig.
2.15Transformationsrelativetothecurrentframes.Example2.8TransformationsRelativetotheRotatingFrametranslationrotationMATRICESFORFORWARD
ANDINVERSEKINEMATICSOFROBOTS•Forposition•FororientationChapter2RobotKinematics:PositionAnalysisFig.2.17Theh
andframeoftherobotrelativetothereferenceframe.ForwardKinematicsAnalysis:•Calculatingthepositionandorientationoft
hehandoftherobot.Ifallrobotjointvariablesareknown,onecancalculatewheretherobotisatanyinstant..FORWAR
DANDINVERSEKINEMATICSOFROBOTSChapter2RobotKinematics:PositionAnalysisForwardKinematicsandInverseKinematicsequationforpositionanalysis:(a)Cartes
ian(gantry,rectangular)coordinates.(b)Cylindricalcoordinates.(c)Sphericalcoordinates.(d)Articulated(anthropomor
phic,orall-revolute)coordinates.ForwardandInverseKinematicsEquationsforPositionChapter2RobotKinematics:PositionAnalys
isIBM7565robot•Allactuatorislinear.•AgantryrobotisaCartesianrobot.Fig.2.18CartesianCoordinates.1000100010001
zyxcartPRPPPTTForwardandInverseKinematicsEquationsforPosition(a)Cartesian(Gantry,Rectangular)CoordinatesChapt
er2RobotKinematics:PositionAnalysis2Lineartranslationsand1rotation•translationofralongthex-axis•rotationofaboutthez-axis•translationoflalongthe
z-axisFig.2.19CylindricalCoordinates.100010000lrSCSrCSCTTcylPR,0,0))Trans(,)Rot(Trans(0,0,),,(rzllrTTcylPRForwa
rdandInverseKinematicsEquationsforPosition:CylindricalCoordinatescosinesineChapter2RobotKinematics:Po
sitionAnalysis2Lineartranslationsand1rotation•translationofralongthez-axis•rotationofaboutthey-axis•rotationofalongthez-axisFig.2.20SphericalC
oordinates.10000rCCSSrSSSCSCCrSCSSCCTTsphPR))Trans()Rot(Rot()(0,0,,,,,yzlrsphPRTTForwa
rdandInverseKinematicsEquationsforPosition(c)SphericalCoordinatesChapter2RobotKinematics:PositionAnalysis3rotations->D
enavit-HartenbergrepresentationFig.2.21ArticulatedCoordinates.ForwardandInverseKinematicsEquationsforPosition(d)ArticulatedCoordinatesCh
apter2RobotKinematics:PositionAnalysisRoll,Pitch,Yaw(RPY)anglesEuleranglesArticulatedjointsForwardandInverseKinematicsEquationsforOrientati
onChapter2RobotKinematics:PositionAnalysisRoll:Rotationofabout-axis(z-axisofthemovingframe)Pitch:Rotationofab
out-axis(y-axisofthemovingframe)Yaw:Rotationofabout-axis(x-axisofthemovingframe)aaononFig.2.22RPYro
tationsaboutthecurrentaxes.ForwardandInverseKinematicsEquationsforOrientation(a)Roll,Pitch,Yaw(RPY)Angle
sChapter2RobotKinematics:PositionAnalysisFig.2.24Eulerrotationsaboutthecurrentaxes.Rotationofabout-axis(z-ax
isofthemovingframe)followedbyRotationofabout-axis(y-axisofthemovingframe)followedbyRotationofabout-axis(z-axisofthemovingframe).aoaForwardandI
nverseKinematicsEquationsforOrientation(b)EulerAnglesChapter2RobotKinematics:PositionAnalysis)()(,,,,noazyxcartHRRPYPPPTT)()(,,
,,EulerTTrsphHRAssumption:RobotismadeofaCartesianandanRPYsetofjoints.Assumption:RobotismadeofaSphericalCoordinateandan
Eulerangle.AnotherCombinationcanbepossible……Denavit-HartenbergRepresentationForwardandInverseKinematicsEquationsforOrienta
tionRoll,Pitch,Yaw(RPY)AnglesForwardandInverseTransformationsforrobotarmsFig.2.16TheUniverse,robot,hand,part,ande
ndeffecterframes.StepsofcalculationofanInversematrix:1.Calculatethedeterminantofthematrix.2.Transposethematrix.3.Replaceeachelementofthet
ransposedmatrixbyitsownminor(adjointmatrix).4.Dividetheconvertedmatrixbythedeterminant.INVERSEOFTRANSFORMATIONMATRIC
ESIdentityTransformations1.WeoftenneedtocalculateINVERSEMATRICES2.Itisgoodtoreducethenumberofsuchoperations3.Weneedtodothesecalculations
fastHowtofindanInverseMatrixBofmatrixA?InverseHomogeneousTransformationHomogeneousCoordinates•Homogeneouscoordinates:embed3
Dvectorsinto4Dbyaddinga“1”•Moregenerally,thetransformationmatrixThastheform:FactorScalingTrans.Perspect.VectorTrans.MatrixRot.Ta11a12a13b1a2
1a22a23b2a31a32a33b3c1c2c3sfItispresentedinmoredetailontheWWW!ForvarioustypesofrobotswehavedifferentmaneuveringspacesForvari
oustypesofrobotswecalculatedifferentforwardandinversetransformationsForvarioustypesofrobotswesolvedifferentforwardandinversekinematicpr
oblemsForwardandInverseKinematics:SingleLinkExampleForwardandInverseKinematics:SingleLinkExampleeasyDenavit–Hart
enbergideaDenavit-HartenbergRepresentation:Fig.2.25AD-Hrepresentationofageneral-purposejoint-linkcombination@Simp
lewayofmodelingrobotlinksandjointsforanyrobotconfiguration,regardlessofitssequenceorcomplexity.@Transform
ationsinanycoordinatesispossible.@Anypossiblecombinationsofjointsandlinksandall-revolutearticulatedrobots
canberepresented.DENAVIT-HARTENBERGREPRESENTATIONOFFORWARDKINEMATICEQUATIONSOFROBOTChapter2RobotKinematics:PositionAnalysis⊙:Arotationanglebetw
eentwolinks,aboutthez-axis(revolute).⊙d:Thedistance(offset)onthez-axis,betweenlinks(prismatic).⊙a:Thelengtho
feachcommonnormal(Jointoffset).⊙:The“twist”anglebetweentwosuccessivez-axes(Jointtwist)(revolute)Onlyanddarejointvariables.DENAVIT-HARTENBERG
REPRESENTATIONSymbolTerminologies:Linksarein3D,anyshapeassociatedwithZialwaysOnlyrotationOnlytranslationOn
lyoffsetOnlyoffsetOnlyrotationAxisalignmentDENAVIT-HARTENBERGREPRESENTATIONforeachlink4linkparametersChapter2RobotKinematics:PositionAnalysis⊙
:Arotationanglebetweentwolinks,aboutthez-axis(revolute).⊙d:Thedistance(offset)onthez-axis,betweenlinks
(prismatic).⊙a:Thelengthofeachcommonnormal(Jointoffset).⊙:The“twist”anglebetweentwosuccessivez-axes(
Jointtwist)(revolute)Onlyanddarejointvariables.DENAVIT-HARTENBERGREPRESENTATIONSymbolTerminologies:Examplewit
hthreeRevoluteJointsi(i-1)a(i-1)dii0000010a0012-90a1d22Z0X0Y0Z1X2Y1X1Y2d2a0a1Denavit-HartenbergLinkParameterTableTheDH
ParameterTableApplyfirstApplylastDenavit-HartenbergRepresentationofJoint-Link-JointTransformationNotationf
orDenavit-HartenbergRepresentationofJoint-Link-JointTransformationAlphaappliedfirstFourTransformationsfromoneJointtotheNext•Orderofmultipli
cationofmatricesisinverseoforderofapplyingthem•HereweshoworderofmatricesJoint-Link-JointDenavit-HartenbergRepresentation
ofJoint-Link-JointTransformation•AlphaisappliedfirstHowtocreateasinglematrixAnEXAMPLE:Denavit-HartenbergRepresentationofJoint-Li
nk-JointTransformationforType1LinkFinalmatrixfrompreviousslidesubstitutesubstituteNumericorsymbolicmatricesTheDenavit-HartenbergMatrixforanoth
erlinktype1000cosαcosαsinαcosθsinαsinθsinαsinαcosαcosθcosαsinθ0sinθcosθi1)(i1)(i1)(ii1)(iii1)(i1)(i1)(ii1)(ii1)(iii
dda•SimilaritytoHomegeneous:JustliketheHomogeneousMatrix,theDenavit-HartenbergMatrixisatransformationmatrixfromonecoordinateframetot
henext.•UsingaseriesofD-HMatrixmultiplicationsandtheD-HParametertable,thefinalresultisatransformationmatrixfromso
meframetoyourinitialframe.Z(i-1)X(i-1)Y(i-1)(i-1)a(i-1)ZiYiXiaidiiPutthetransformationhereforeverylink1.InDENAVIT-HARTENBERGREPRESENTATIONwemustbeab
letofindparametersforeachlink2.SowemustknowlinktypesLinksbetweenrevolutejointsln=0Type3LinkJointn+1Jointndn=
0Linknxn-1xnln=0dn=0Type4LinkOriginscoinciden-1Jointn+1JointnPartofdn-1Linknxn-1yn-1xnnLinksbetweenprismaticjoin
tsForwardandInverseTransformationsonMatricesStartpoint:•Assignjointnumberntothefirstshownjoint.•Assignaloca
lreferenceframeforeachandeveryjointbeforeorafterthesejoints.•Y-axisisnotusedinD-Hrepresentation.DENAVIT-HARTENBERGREPRESENTATIONPROCED
URES.1٭Alljointsarerepresentedbyaz-axis.•(right-handruleforrotationaljoint,linearmovementforprismaticjoint)2.Thecommon
normalisonelinemutuallyperpendiculartoanytwoskewlines.3.Parallelz-axesjointsmakeainfinitenumberofcommonnormal.4.Intersecting
z-axesoftwosuccessivejointsmakenocommonnormalbetweenthem(Lengthis0.).DENAVIT-HARTENBERGREPRESENTATIONProcedu
resforassigningalocalreferenceframetoeachjoint:Chapter2RobotKinematics:PositionAnalysis⊙:Arotationaboutthez-axis.⊙d:Thedistan
ceonthez-axis.⊙a:Thelengthofeachcommonnormal(Jointoffset).⊙:Theanglebetweentwosuccessivez-axes(Jointtwist)Onlyanddarejointva
riables.DENAVIT-HARTENBERGREPRESENTATIONSymbolTerminologiesReminder:Chapter2RobotKinematics:PositionAnalysis(I)Rotateab
outthezn-axisanableofn+1.(Coplanar)(II)Translatealongzn-axisadistanceofdn+1tomakexnandxn+1colinear.(III)Translatealongthexn-axisadistanceofan+1tobri
ngtheoriginsofxn+1together.(IV)Rotatezn-axisaboutxn+1axisanangleofn+1toalignzn-axiswithzn+1-axis.DENAVIT-HARTENBERGRE
PRESENTATIONThenecessarymotionstotransformfromonereferenceframetothenext.