无线视频监控系统中英文.docx

无线视频监控系统中英文.docx

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无线视频监控系统中英文

英文资料及中文翻译

Developmentofamulti-agentsystemforrobotsoccergame

一、Introduction

Asmodernindustrialsocietyprogresses,theneedsforusefulrobotsaregrowing.Especially,mobilerobotsarespecialissuethatgraduallyexpandsitsrealminindustrialandstudyingtopics.Researchesonmobilerobotshavebeenmainlyconcentratedonsinglemobilerobot.But,thedevelopmentofmulti-agentsystemisstronglyneededbythegrowthofcomplexityoftasksforrobotstoperform.

Themulti-agentsystemshavebeenstudiedbymanyresearchers[l-3].Generally,multi-agentsystemisdefinedasthesystemcomposedofmorethan2robots[4]andperformsthegiventaskbycooperation.Thesystemhassomedifferentfactorscomparedwithsinglerobotsystem.First,theenvironmentforrobotstoconfrontisdynamic.Inmulti-agentsystem,therobotsthemselvesconstitutedynamicenvironment,becauseeachrobotshouldrecognizetheotherrobotsasmovingobstacles.Manypreviousresearchesonmobilerobotsassumethattheenvironmentisstatic,evenfortheresearchesonsinglemobilerobot[5,6].Second,sincethesystemperformsgiventaskbycooperation,itisnecessarytomakeoverallsystemplanforrolesofrobots.Oneoftheobviouscharacteristicsofthemulti-agentsystemiscooperation-forexample,4-5robotscarryfurniture[7].Tocooperateoneanother,thechangesofrobotspositionmustbepredictable.Therearesomewaystoknowtherobotsposition.Forexample,robotscommunicatetheirpositiononeafteranother,orasupervisordetectsrobots'positionandtransmitsthemtorobots.Itisrelatedtocommunicationproblem.Third,eachcomponentofthesystemsuchasrobots,asupervisor,sensors,communicationequipmentiswelldeveloped,becausetheyinfluencetheoverallsystemperformance.Also,itisnecessarytoadoptappropriatearchitecture.

Robotsoccerisaninterestingdomainforstudyingthemulti-agentsystem.Theplayersmustworktogether:

Itmeansasortofcooperation.Also,theyplaythegameindynamicenvironment:

predictableandunpredictableenvironment-ourrobotsandopponent'srobots,respectively.Themainobjectistoputtheballinopponent'sgoalasfrequentlyaspossibleinpresenceofopponent'srobotswhichhavethesametask.So,accordingtoasituation,ourrobotsdecidewhichactiontheytake-defenseoroffense,howtheyworkandsoon.Inthispoint,thesystemneedsreal-timesensing,quickdecisionmakingandfastbehaviors.Itisrelatedtosystemarchitectureandalgorithms.Asdescribedabove,soccergameincludesmanycharacteristicsofmulti-agentsystemandisabundantinapplyingAItechniques.

Oneoftheadvantagesofrobotsoccergameisdirectcomparisonofdifferentsystems.Manyrobotsoccersystemsaregatheredinsomecompetitions.WeparticipatedinaSoccerrobotcompetitioninTaejon,KoreacalledMIROSOT96[8].MIROSOTmakessomerules.Therulesdescribeprecisespecificationforsoccergame.Theplaygroundisrectangularwithitslength130cm,itswidth90cm.Anorangegolfballisselectedastheplayball.Thesizeofarobotisrestrictedwithin7.5*7.5*7.5cm.Oneteamconsistsofthreerobots.Wepurposetomakesoccersystemwiththreerobots.

Inthispaper,weexplainsomefactorstobeconsideredinestablishingcompletesystem.First,sincethesystemarchitectureisveryimportant,wedecidetheoverallsystemasacentralizedon-linesystemonthebasisofsurveysofmulti-agentsystems.Second,theoverallsystemcanbedividedintothreeparts-Arobot,communicationandvisionsystem.Wedescribethespecificationsofcomponentsofeachpartandthereasonstodecidethem.Itwouldbehelpfulforlaterimprovement.

Therestofthepaperisorganizedasfollows.Section2givessomesurveysofsystemarchitecturesandselectionofoursoccerrobotsystem.Section3givesdetaileddescriptionsofimplementedhardware,especiallyminirobots.Section4givescooperationandpathplanalgorithmforrobotsoccergame.Section5givesconclusionofthispaperandpresentsfurtherworks.

二、Categorizationofmulti-agentsystemandselectionofsoccerrobotsystem

ThesurveyonthisissueiscloselyrelatedinArai'swork[4].Wecancategorizemulti-agentsystembasedontwocriteria.Oneis"Whomakesdecisionandorders?

"-Centralized/Decentralized,theotheris"Whendoesthesystemmakeplans?

"-Online/Offline.

Centralizedsystemmeansthatasupervisorintegratesallavailabledata,plansthebehaviorsofalltherobotsandmakescommands.Sinceasupervisorconsidersalltherobotssimultaneously,thesystemcanachievetheoptimizationofthemotionsofalltherobots.But,asthenumberofrobotincreases,morecomputationalpowerofasupervisorisneeded.Ifthesupervisormakesanyfault,thereisnowayfortherobotstocorrectit.

Decentralizedsystemmeansthateachrobotmakesplanforitselfonthebasisofcollectedinformationfromotherrobotsanditsownsensors.Inthesystem,thereisnotconsiderableincreasingcomputationalloadasthenumberofrobotsincreases.Evenifonerobotfailstowork,otherrobotsworkwell.But,thesystemcannotguaranteetheoptimizationofthemotionsofalltherobots.

Off-linesystemmeansthatallthepathsareplannedbeforealltherobotsmove.Becauseofnorestrictionoftimeandcomputingpower,thesystemcanachieveoptimization.But,sincethesystemassumesstaticenvironment,itisnotrobusttosmallvariationofenvironment.Inrealworld,itmaymalfunctionwithsomevariances.

On-linesystemmeansreal-timeplanning.Itisrobusttodynamicenvironment.But,itneedslargecomputationalpowerandeffectivealgorithm.

Inalotofresearches,theabovetwocategorizationsareinterrelatedeachother.WesummarizetheresearchesinTable1.

Table1.Categorizationofmulti-agentsystem

who

when

proposedmethods

Centralized

Off-line

cellDecomposition^]Retraction[10]Priority[5,6]

Centralized

On-line

Decentralized

Off-line

Priority[ll]

Decentralized

On-line

PotentialField[12]

Rule-based[13]

Communication[14]

InMIROSOT96,Thesizeofarobotisrestricted.Therefore,itisdifficulttoimplementarobotwithlargecomputationalpower.Also,itisimportanttodecidewhatarobotmustequip.Basically,arobothastoequipactuatormoduleandcommunicationmodule.Additionalequipmentsareselectedandimplementedconsideringthespaceofarobot.Soccergameneedsglobalinformationofourrobots'position.So,wedecidethecentralizedsystemasoursystem.Fromtheviewpointofpathplanningtime,wedecidetheon-linesystem.Soccergamehasfastchangingnatureandnecessitatesreal-timesensing,fastbehaviors,andquickdecisionmaking.Itisreasonabletoadopton-linesystem.

Incentralizedon-linesystem,asupervisoracquiresallavailableinformationofwholeenvironmentandtherobots.Simultaneously,asupervisorshouldplanalltherobots'pathsinreal-time.Thereforeitrequiresfastcomputingpower.Todecreasetheburdenofasupervisor,wechoosepartitionedsystemwhichseparatemainplanningandexecuting.ThisissomewhatsimilartotheworksofShakey[15],Firby[16].Inoursoccerrobotsystem,asupervisormakesplansofalltherobotsonthebasisofsomestrategy.Then,asupervisortransmitsnextdesiredpositiontoeachrobot.Eachrobotreceivesdesiredpositionandexecutesitscontrolalgorithmforpositionandvelocitycontrols.Simultaneously,eachrobottakesdataofitsownlocalsensorwhicharefusedwithdesiredpositionintodesiredinputofitsowncontrolloop.Therefore,arobotmustpossesssomelogic:

asortofa"brain".So,ourrobotshavemicro-controllers.Inthisarchitecture,thesystempartitionscomputingburdens.Figure1showsthefunctionaldiagramofoursoccerrobotsystem.Sinceasupervisorreceivespositionsoftheballandallrobots,thesystemdoesn'tneedbi-directionalcommunication.Asupervisoronlytransmitscommandstoeachrobot.Inthecaseofbi-directionalcommunication,thelogicoftransmittingandreceivingorderandprioritymustbeneeded.Itmayincreasecomplexityofcommunicationsystemofbothasupervisorandarobot.

Figure1.Theconstitutionofoursoccerrobotsystem

三、Systemimplementation

Systemiscomposedofthreeparts-asupervisor,visionand5robots.AsupervisorisaPC-pentiumprocessor-whichmakesplaninrealtime,andvisionsystemhastwocameraswhichhaveredandbluefilterrespectively,andimageprocessingboardwhichhasaDSPandmemory.ArobothasaCPU,communicationmodule,IRsensors,motors,etc.Thesethreepartsarerelatedoneanother.Detaileddescriptionsaregiveninfollowingchapters.

1.Configurationofindividualrobot

Arobotisconsistedofmechanicalpart,CPUboard,communication（receiver>moduleandsensorboard.Itssizeiswithin7.5*7.5*7.5cm.

2.Mechanicalpart

Mechanicalpartofarobotisconsistedoftwomotors,encoders,gearheads,wheels,aballcaster,andaframe.Theframeisdesignedforeasy,compactandhardyintegration.Motorsandgearheadsareselectedinconsiderationforoperatingvoltage,internalresistance,mechanicaltimeconstant.Itsoperatingvoltageis6V.Reductionratioofgearheadis1:

41.Adiameterofawheelis32mm.Theno-loadspeedofamotoris15200rev/min.So,no-loadspeedofrobotscanbecalculatedasabout62cm/sec.Inrealrobots,wemeasurethemaximumspeedofarobot.Theresultisabout40cm/sec.TwomotorsarecontrolledbyaCPUinmainboardindependently.Theencodergenerates16pulsesperrevolution.

3.CPUboardandsensorboard

Figure2.TheCPUboardandsensorboard

（a）thelocationsofLEDsinCPUboardforrobot'spositionandrotation

（b）thelocationsofIRsensorsinsensorboard

InCPUboard,