机器人路径规划论文外文翻译Word下载.docx
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外文文献:
SpaceRobotPathPlanning
forCollisionAvoidance
YuyaYanoshitaandShinichiTsuda
Abstract—Thispaperdealswithapathplanningofspacerobotwhichincludesacollisionavoidancealgorithm.Forthefuturespacerobotoperation,autonomousandself-containedpathplanningismandatorytocaptureatargetwithouttheaidofgroundstation.Especiallythecollisionavoidancewithtargetitselfmustbealwaysconsidered.Oncethelocation,shapeandgrasppointofthetargetareidentified,thosewillbeexpressedintheconfigurationspace.Andinthispaperapotentialmethod.
Laplacepotentialfunctionisappliedtoobtainthepathintheconfigurationspaceinordertoavoidso-calleddeadlockphenomenon.Improvementonthegenerationofthepathobservedbyapplyingpathsmoothingmethod,whichutilizesthesplinefunctioninterpolation.Thisreducesthecomputationalloadandgeneratesthesmoothpathofthespacerobot.Thevalidityofthisapproachisshownbyafewnumericalsimulations.
KeyWords—SpaceRobot,PathPlanning,CollisionAvoidance,PotentialFunction,SplineInterpolation
I.INTRODUCTION
Inthefuturespacedevelopment,thespacerobotanditsautonomywillbekeyfeaturesofthespacetechnology.Thespacerobotwillplayrolestoconstructspacestructuresandperforminspectionsandmaintenanceofspacecrafts.Theseoperationsareexpectedtobeperformedinanautonomous.
Intheabovespacerobotoperations,abasicandimportanttaskistocapturefreeflyingtargetsonorbitbytheroboticarm.Forthesafecapturingoperation,itwillberequiredtomovethearmfrominitialposturetofinalposturewithoutcollisionswiththetarget.
Theconfigurationspaceandartificialpotentialmethodsareoftenappliedtotheoperationplanningoftheusualrobot.Thisenablestherobotarmtoevadetheobstacleandtomovetowardthetarget.Khatibproposedamotionplanningmethod,inwhichbetweeneachlinkoftherobotandtheobstacletherepulsivepotentialisdefinedandbetweentheend-effecteroftherobotandthegoaltheattractivepotentialisdefinedandbysummingbothofthepotentialsandusingthegradientofthispotentialfieldthepathisgenerated.Thismethodisadvantageousbyitssimplicityandapplicabilityforreal-timeoperation.Howevertheremightbepointsatwhichtherepulsiveforceandtheattractiveforceareequalandthiswillleadtotheso-calleddeadlock.
Inordertoresolvetheaboveissue,afewmethodsareproposedwherethesolutionofLaplaceequationisutilized.Thismethodassuresthepotentialfieldswithoutthelocalminimum,i.e.,nodeadlock.InthismethodbynumericalcomputationLaplaceequationwillbesolvedandgeneratespotentialfield.Thepotentialfieldisdividedintosmallcellsandoneachnodethediscretevalueofthepotentialwillbespecified.
Inthispaperfortheeliminationoftheabovedefects,splineinterpolationtechniqueisproposed.Thenodalpointwhichisgivenasapointofpathwillbedefinedtobeapartofsmoothedsplinefunction.Andnumericalsimulationsareconductedforthepathplanningofthespacerobottocapturethetarget,inwhichthepotentialbysolvingtheLaplaceequationisappliedandgeneratesthesmoothandcontinuouspathbythesplineinterpolationfromtheinitialtothefinalposture.
II.ROBOTMODEL
ThemodelofspacerobotisillustratedinFig.1.
Therobotismountedonaspacecraftand-planemotionoftheend-effecter.Inthiscaseweadditionalfreedomofthespacecraftattitudeangleandthiswillbeconsideredtheadditionalrotaryjoint.Thismeansthatthespacerobotisthreelinkedwith3DOF(DegreeOfFreedom).Thelengthofeachlinkandtheangleofeachrotaryjointaregivenbyand(i=1,2,3),respectively.Inordertosimplifythediscussionsafewassumptionsaremadeinthispaper:
-themotionofthespacerobotisin-plane,i.e.,twodimensionalone.
-effectofrobotarmmotiontothespacecraftattitudeisnegligible.
-robotmotionisgivenbytherelationofstaticgeometryandnotexplicitlydependingontime.
Fig.1ModelofTwo-linkSpaceRobot
III.PATHPLANNINGGALGORITHM
A.LaplacePotentialGuidance
ThesolutionoftheLaplaceequation
(1)iscalledaHarmonicpotentialfunction,anditsandminimumvaluestakeplaceonlyontheboundary.Intherobotpathgenerationtheboundarymeansobstacleandgoal.Thereforeinsidetheregionwherethepotentialisdefined,nolocalminimumtakesplaceexceptthegoal.Thiseliminatesthedeadlockphenomenonforpathgeneration.
(1)
TheLaplaceequationcanbesolvednumerically.WedefinetwodimensionalLaplaceequationasbelow:
(2)
AndthiswillbeconvertedintothedifferenceequationandthensolvedbyGauss-Seidelmethod.Inequation
(2)ifwetakethecentraldifferenceformulaforsecondderivatives,thefollowingequati