机器人外文翻译外文文献英文文献采用模糊逻辑控制使自主机器人避障设计.docx
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机器人外文翻译外文文献英文文献采用模糊逻辑控制使自主机器人避障设计
Autonomousrobotobstacleavoidanceusingafuzzylogiccontrolscheme
WilliamMartin
SubmittedonDecember4,2009
CS311-FinalProject
1.INTRODUCTION
Oneoftheconsiderablehurdlestoovercome,whentryingtodescribeareal-worldcontrolschemewithfirst-orderlogic,isthestrongambiguityfoundinbothsemanticsandevaluations.Althoughoneoptionistoutilizeprobabilitytheoryinordertocomeupwithamorerealisticmodel,thisstillreliesonobtaininginformationaboutanagent'senvironmentwithsomeamountofprecision.However,fuzzylogicallowsanagenttoexploitinexactnessinitscollecteddatabyallowingforaleveloftolerance.Thiscanbeespeciallyimportantwhenhighprecisionoraccuracyinameasurementisquitecostly.Forexample,ultrasonicandinfraredrangesensorsallowforfastandcosteffectivedistancemeasurementswithvaryinguncertainty.Theproposedapplicationsforfuzzylogicrangefromcontrollingrobotichandswithsixdegreesoffreedom1tofilteringnoisefromadigitalsignal.2Duetoitseasyimplementation,fuzzylogiccontrolhasbeenpopularforindustrialapplicationswhenadvanceddifferentialequationsbecomeeithercomputationallyexpensiveoroffernoknownsolution.Thisprojectisanattempttotakeadvantageofthesefuzzylogicsimplificationsinordertoimplementsimpleobstacleavoidanceforamobilerobot.
2.PHYSICALROBOTIMPLEMENTATION
2.1.Chassisandsensors
Theroboticvehicle'schassiswasconstructedfromanExcaliburEI-MSD2003remotecontroltoytank.Thedevicewasstrippedofallelectronics,gears,andextraneouspartsinordertoworkwithjusttheemptycaseandtwoDCmotorsforthetanktreads.However,thisleftasomewhatunevensurfacetoworkon,sohigh-densitypolyethylene(HDPE)rodswereusedtofillinemptyspaces.SinceHDPEhasaratherlowsurfaceenergy,whichisnotidealforbondingwithothermaterials,apropanetorchwasusedtoraisesurfacetemperatureandimprovebondingwithanepoxyadhesive.
ThreeSharpGP2D12infraredsensors,whichhavearangeof10to80cm,wereusedfordistancemeasurements.Inordertomounttheseappropriately,a2.5by15cmpieceofaluminumwasbentintothreeevenpiecesat135degreeangles.ThisallowsfortheIRsensorstotakethreedifferentmeasurementsat45degreeangles(right,middle,andleftdistances).ThissensormountwasthenattachedtoanHDPErodwithmountingtapeandtherodwasgluedtothetankbasewithepoxy.Sincetheminimumdistancethatcanbereliablymeasuredwiththesesensorsis10cm,thesensorswereplacedabout9cmfromthefrontofthevehicle.Thisallowedmeasurementstobetakenveryclosetothefrontoftherobot.
2.2.Electronics
Inordertocontrolthespeedofeachmotor,pulse-widthmodulation(PWM)wasusedtodrivetwoL2722opampsinopenloopmode(Fig.1).ThehighinputresistanceoftheseICsallowforthemotorstobepoweredwithverylittlepowerdrawfromthePWMcircuitry.Inordertoisolatethemotor'spowersupplyfromtherestoftheelectronics,a9.6VNiCadbatterywasusedseparatelyfromastandard9Vthatdemandontheopampsledtoasmallamountofoverheatingduringcontinuousoperation.Thiswasremediedbyaddingsmallheatsinksandafantotheforciblydisperseheat.
Fig.1.ThecontrolcircuitusedfordrivingeachDCmotor.NotethatthePWMsignalwasbetween0and5V.
2.3.Microcontroller
ComputationwashandledbyanArduinoDuemilanoveboardwithanATmega328microcontroller.Theboardhaslowpowerrequirementsandmodifications.Inaddition,ithasalargenumberofprototypingofthecontrolcircuitandbasedontheWiringlanguage.Thisboardprovidedaneasyandlow-costplatformtobuildtherobotaround.
3.FUZZYCONTROLSCHEMEFOR
Inordertoapplyfuzzylogictotherobottointerpretmeasureddistances.Whilethefinalalgorithmdependedcriticallyonthegeometryoftherobotitselfandhowitoperates,somebasicguidelineswerefollowed.Similarresearchprojectsprovidedbothsimulationresultsandideasforimplementingfuzzycontrol.3,4,5
3.1.Membershipfunctions
Threesetsofmembershipfunctionswerecreatedtoexpressdegreesofmembershipfordistances,translationalspeeds,androtationalspeeds.Thismadeforatotaloftwoinputmembershipfunctionsandeightoutputmembershipfunctions(Fig.2).Triangleandtrapezoidalfunctionswereusedexclusivelysincetheyarequicktocomputeandeasytomodify.Keepingcomputationtimetoaminimumwasessentialsothatmanysetsofdatacouldbeanalyzedeverysecond(approximatelyoneevery40milliseconds).ThedistancemembershipfunctionsallowedthedistancesfromtheIRsensorstobequickly"fuzzified,"whiletheeightspeedmembershipfunctionsconvertedfuzzyvaluesbackintocrispvalues.
3.2.Rulebase
Oncetheinputdatawasfuzzified,theeightdefinedfuzzylogicrules(TableI)wereexecutedinordertoassignfuzzyvaluesfortranslationalspeedandrotation.Thisresultedinmultiplevaluesfortheeachofthefuzzyoutputcomponents.Itwasthennecessarytotakethemaximumofthesevaluesasthefuzzyvalueforeachcomponent.Finally,thesefuzzyoutputvalueswere"defuzzified"usingthemax-producttechniqueandtheresultwasusedtoupdateeachofthemotorspeeds.
(a)
(b)
(c)
Fig.2.Themembershipfunctionsusedfor(a)distance,(b)translationspeed,and(c)rotationalspeed.Thesefunctionswereadaptedfromsimilarworkdoneinreference3.
4.RESULTS
Thefuzzycontrolschemeallowedfortherobottoquicklyrespondtoobstaclesitcoulddetectinitsenvironment.Thisallowedittofollowwallsandbendaroundcornersdecentlywithouthittinganyobstacles.However,sincetheIRsensors'measurementsdependedonthegeometryofsurroundingobjects,thereweretimeswhentherobotcouldnotdetectobstacles.Forexample,whentheIRbeamhitasurfacewithobliqueincidence,itwouldreflectawayfromthesensorandnotregisterasanobject.Inaddition,thelimitednumberofrulesusedmayhavelimitedthedynamicsoftherobot'sresponses.Somearticlessuggestasmanyasfortyrules6shouldbeused,whileotherstendtopresentbetweentenandtwenty.Sincethisprojectdidnotexplorecomplexkinematicsorcomputationalsimulationsoftherobot,itisdifficulttodetermine
exactlyhowmanyrulesshouldbeused.However,forthepurposesoftestingfuzzylogicasanavigationalaide,theeightrulesweresufficient.DespitethemanyproblemsthatIRandsimilarultrasonicsensorshavewithreliablyobtainingdistances,therobustnessoffuzzylogicwasfrequentlyabletopreventtherobotfromrunningintoobstacles.
5.CONCLUSION
Thereareseveraleasyimprovementsthatcouldbemadetofutureiterationsofthisprojectinordertoimprovetherobot'sperformance.ThemostdramaticwouldbetoimplementtheIRorultrasonicsensorsonaservosothattheycouldeachscanafull180degrees.However,thistypeofoverhaulmayunderminesomeoffuzzylogic'shelpfulsimplicity.Anotherhelpfultacticwouldbetouseafewtypesofsensorssothatdatacouldbetakenatmultipleranges.TheIRsensorsusedinthisexperimenthadaminimumdistanceof10cm,soanythinginfrontofthiscouldnotbereliablydetected.Similarly,thesensorshadamaximumdistanceof80cmsoitwasdifficulttoreacttoobjectsfaraway.Ultrasonicsensorsdooffersignificantlyincreasedrangesataslightlyincreasedcostandresponsetime.Lastly,definingmoremembershipfunctionscouldhelpimprovetherulebasebycreatingmorefinetunedresponses.However,thiswouldagainincreasethecomplexityofthesystem.
Thus,thisprojecthassuccessfullyimplementedasimplefuzzycontrolschemeforadjustingtheheadingandspeedofamobilerobot.Whileitisdifficulttodeterminewhetherthisisaworthwhileapplicationwithoutheavilyresearchingothermethods,itisquiteapparentthatfuzzylogicaffordsacertainlevelofsimplicityinthedesignofasystem.Furthermore,itisanovelapproachtodealingwithhighlevelsofuncertaintyinreal-worldenvironments.
6.REFERENCES
1Ed.M.Jamshidi,N.Vadiee,andT.Ross,Fuzzylogicandcontrol:
softwareandhardwareapplications,(PrenticeHall:
EnglewoodCliffs,NJ)292-328.
2Ibid,232-261.
3W.L.Xu,S.K.Tso,andY.H.Fung,"Fuzzyreactivecontrolofamobilerobotincorporatingareal/virtualtargetswitchingstrategy,"RoboticsandAutonomousSystems,23(3),171-186(1998).
4V.PeriandD.Simon,“Fuzzylogiccontrolforanautonomousrobot,”2005AnnualMeetingoftheNorthAmericanFuzzyInformationProcessingSociety,337-342(2005).
5A.Martinez,E.Tunstel,andM.Jamshidi,"Fuzzy-logicbasedcollision-avoidanceforamobilerobot,"Robotica,12(6)521–527(1994).
6W.L.Xu,S.K.Tso,andY.H.Fung,"Fuzzyreactivecontrolofamobilerobotincorporatingareal/virtualtargetswitchingstrategy,"RoboticsandAutonomousSystems,23(3),171-186(1998).
采用模糊逻辑控制使1自主机器人避障设计
WilliamMartin威廉马丁
SubmittedonDecember4,2009提交于2009年12月4日
CS311-FinalProjectCS311-最终项目
1.1INTRODUC引言
Oneoftheconsiderablehurdlestoovercome,whentryingtodescribeareal-world其中一个很大的障碍需要克服,当试图用控制逻辑一阶来描述一个真实世界设计在发现在这两个语义evaluations.评价中controlschemewithfirst-orderlogic,isthestrongambiguityfoundinbothsemanticsand设计设计设计是个强大的模糊区。
Althoughoneoptionistoutilizeprobabilitytheoryinordertocomeupwithamo虽然一个方案是利用概率论,以便得到一个更realisticmodel,thisstillreliesonobtaininginformationaboutanagent'senvironmentwithsome现实的模型,这种获得信息的方法的精度仍然依赖于外部环境amountofprecision.。
然而,在其收集databyallowingforaleveloftolerance.数据的公差允许的范围内,模糊逻辑允许利用不精确的间接方法来实现。
在需要高精度oraccuracyinameasurementisquitecostly.测量时它是相当昂贵的。
例如,超声波和红外线传感器在其距