P「oceedingSofthe2003IEE曰RSl
Inll.C、n6e「enceonlnteIIigentRobolsandSyslems LasVegas,NevadaOctober2003
AdaptiveAudioServohr MultirateRobotSystems
MakotoKUMON,ThkahiroSUGAWARA,KatuhiroMⅡKE,IkumMIZUMOrOandZentalWAI DepartmentofMechanicalEngineeringandMaterialsScienCe,KumamotoUniveI5ity
231-1,KUmkami,Kumamoto,860-8555,Japan EJ『miMJUmo"@gpMEJmamom-UU.αQjP
ABSTRACT Obstac1esbctweenthetargetandd1ccamera・IIMhose lnthispaperbaMdioserv0M》orの】SEC"zwhichwas cases,animalsmayuseothersensorssuchasearsto
aservosystemusim】gaudioinfOnnationasfeedbackove1℃omcCmiiculties・Thesenseofheamnghasan
abniWtosenseobjectsbehindObstaclessuChthat signalwasconsidered・SincethesampUngrateof
audiosignalandlhatofIDbotcontroHeraIeUsuany eyescannotrecognize・Thoughthesenseofhearing difhenMheSystemisabletobetreatedasamulti‐ maybethoughttobelessplecisethanthesenseof ratesystcm・SinceitisgeneralthatthesampUng vision,itoffersenoughinfbnnationfbrdai1ytaSks・
rateoftheoUlPutisfasterthanthatoftheinput, FDrexample,skiUedpeOpleareabletowalkalong thecontmllercanobtainmoreinfbnnationthana waUswiththeireyesclosedonlybyliSteningechos single-rateservosystemByuSingthispmpemVban oftheirsteps[4]・Itisalsoworthnotingthatalldio infbrmationisusuanyldimensionaltimcSeriesand adaptiveauddoservosystemwaspmposed・Results
ofacomputersimulationandaexpeIimentshowed itisthOughttobeeaSiertoextractthecuewbich e6fectivenessofthemethod・ isrequhedby,acontmUersincevisUalinfmmation is2dimensionaltimeserieSwhichreqUiIcshuge l・INTRODUCTIONcomputationtOeXtractmeaningfUlinfbrmation・Ac- cordinglybaservoSystemusingaudioMbnnation Animalshavevarioussensingabilitiessuchas itselfbWhichiscaUeda腿diDseFTo・isconside1℃d vision,hearing,tactnCpemeptionandsoon、T11ose
inthiSpapeⅢOneofinterestingapp1icationsof sensingabilitiesareusuallycombinedwiththeir
audioservoisasoPhisticatedhumanoidstalkingwith moUonsanditmakespossiblefbrthemtoadapt humansn.
thesurroundingenvimnment、FOrexamp1e,eycsand
handsa1℃WellcoordinatedWhenananimaliscap‐Tbthisend,soundsignaliMequiredtObepro‐
、tulinganobjectandtheanimaliMbletosucceedcessedtoextractcuesl4]whichare剛mredbythe this・taskevenifthetaIgetismovmg.~CO別tldler・Inordertocxtmctthecue,thercisa lnordertomakerobotsbesknlfilIasanimalsaエe,methodwhichestimatesthepositionofthesound thesesensor-motioncoordinationhavebeenstudUed.souI℃ebyusing3CUmensionalworldmode】([6L【7]).
ESpeciallyWisionhasattractedmanyrBsearchers[1]HOWeveMhisapproaChtendstobecomp腕and
andInanyvision-basedorvision-guidedmotioncon- 3CmnensionalworldreconstmctiOnmaybemme tm1methodsfbrintenigentmachineshavebeen infbnnationthanlcquilcd・FUrthermoI巳,thesystem proposed[2][3)DWingtotheg剛pmgrcssofdigitalisprefer[edtobesimple・Thercfb[巳,itisproposedto processorS,itbecomeseasiertodesi印arObotwithfeedbackmteredsoundsignaMtSelfdireCUytothe visionsensorssuchasCCDcamelas急VisualservoI2]controllerinthispapeLGenemllyspeaking,since isoneofcontmlschemesusingvisionsystemssamp1inglatesofi叩ut(commandstome(hanical tocontmlmbotsbyusingviSualinfbnnationwithsystems)andoutput(audioinfbrmation)ofthesystem simPlefbrmandithasbeenstudiedvigomusly. /mediffBrent,theconsidercdsystemisamulti-】臼te Thou8hvisionsensorsoffbrrichinfbrmationofthesyStemwhichhasbeenStudied(e69.[8],[,])Itis eIMmnmentamundthemboLthey肥quirealotofnatulH1thatsoundSi印alissampledaMasterrate
comPutationtoextmctintIinsicinfblmation,orac"a thanthemtewhichmbotsaI巳contmnedat・Owing Andthcyaresometimesinterferedbydeadanglesortothis,itispossibletoimplcvetheperfbmlanceof
W803p7860WD鯛17.00,2003IEEE182
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()
0.1
鑿 ServoMotor Con2mU1er 詞0
-0.1
Fig’1.AudioServoSystem
-0.2 ‐100-50050mo
ae
Fig2、Relationbetweentheoutputofthesystem(9)andthe orientatiOntothesoundsoume(仏)
theSys6emsincethesyStemisabletoObtainmore infmnationthanthecontmner比quiri9S・Inthispapen anadaptivecontmMhemefmaverySimPleaUdio servosystemispmposedbyusingthefast急、teoutput oflhesystem
lnSectionll,detailsofaudiOservosystemwhich isconsideH巳dinthisp8Perareshown.、lecontrO1 schemeisprOposedinSectionllLInortlertoshow effectivenessofthepmposedmethod,resultsofa ComputersimulatiOnandthoseofanexPerimentarc showninSeCtionSectionⅣandSectiOnV肥spec‐
tively・T11ensomeconcHudinglCmarksandfhtur己 worksaIMenoted(SectionVI).
ILAuDIOSERvoSYsTEM
Inlmspap甑ase[vosyStemthatuseSaUdio infbnnationiscaUedqJudioSenJo3ysnem.hother wordMheObjectiveoftheaudioservosyStemisto makethestateofthcsystemconvelgetothedesired Statebyusingaudioinfbrmationitself
USUanyaudioinfbnnationcanbeObtainedatfaster ratethanattheratewhichmechaniCalmbotsystems arecontmUed・ForCxampIe,sUpPOsethataudiosig‐
、alissampledat44100Hz(CDmte)andthatarobot iscontrDUedbyaConlroI1erateaChO・Ssecondln thiscase,thesystemisabletoobtaintheaudiosignal
響2-20000timesfasteMlanthecontroU1eris aⅡ;】もtocontm】thembot、IT1isimPUesthattheaudio
servDsystemisabletoimpMethepeIfbnnanceof thecontmmerbyusingaudioinfbnnationduringtl1e salnplingPericdofthecontrolle凪
Figurc1・showsthesystemwhichisconsidcred inthispapelkTWomicmphonesa[eembeddedina dunmyheadwhichisattachedtoarObotsystem,
andthosencmPhonesobservethesoundfmma Speaker(soundsouzce).IMstheObjectivefbrthis systemtomakeonentationofthedummy-headd雌ct tothesoundsoumebyusingtheaudiOinfbrmation.
、】csignalfiommicmphonesisamplified,sampled aM4100Hzandpre-pmcessedbydigjtalsignalpm- cessor(DSP)asfOUows:
眺(ん)-鮒(ん)
g(〃)=lgI(ん)|+12〃(k)|+胸, (1)
Where軌(ん)and鮒(虎)repI巳sentthesigna】危om lefUhightmicmphonesattimc肺speCtivelyW(ん)is theoutputoEthesystemanditisthefilteredsignal fbrthecontrollelWoisasmallpositiveconstantto plpvcntthedenominatorof(1)fiomvanishing・
Thecontronercontro1stheorientationofthc
dummy=headbyusingIhenlter己dsigMll9(彫).Let denotetheOrientationofthedUmmy-headasO(k).
Inthispap甑thefbllowingsilnplecaseisconsiderCd・
Thembot,onwhichthedummy-headisiixed,has onlyldegreeOffiBedom,i、e・mtationalmotion,and commandstOtherobota1℃acceptedtwiceasccond・
mecommandindicatesthedeshCddilectionofthe
dummy-headanditisprOcessedbytheservomotor controllerbnlesettlingtimeoftheservomotoris aboutO3seconddependingonthemagnitudeOfthe
cOmmand.}
NOwbdefinetheangledeaSfbllowS:
“(ん)=0(ん)-ぬ,(2)
where8drepresentstheorientationofIhesound soumaWiththisnotation,thecontmlObjectiハノecan beIBwrittenasletOb(虎)→Oasルーoobyusing audiosignalg(ん).Nmethatthesystemmustnot reqUir巳thevalueofOtl・
nDe剛ationbetweengandtheangleOeisidenti‐
fiedIhmughexperimcntsanditisshowninFignlre2.
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WhenthesoundsourccislocatedinnDntofthe
dummy-head,thatis-90o<0e<90.,yis monotonicaUyincleasingwithrespecttMbandy isaImostOwhenOb=0.nlelefOrc,itisnatum】
tomodeMhelelation(oranoutputfilnctionofthe system)betweenWanMeasfbllows:
v(ん)=50e(代),、(3)
wherMisanon-zeroconstant・ThisimpUesthat Oe(ん)=O幹w(ん)=0,
andthatthecontmlobjectivMe(ん)→Ocanbe achicvedwhenV(ん)→0.TheIBfbre,itcanbe conclUdedlhattheaudioservosystemisabletobe implementedbyuSingsoundsignamromthedunmy‐
head.
theconve堰encemte,thevalueofK(〃T)isEequM
tobeequaltMhatof;sincethecontmllcrmakes
8e((冗十1)T)becomeOInthisp叩飢amcihod toestimatethisadCquatevaluewithoutap巾冗 infOrmationof6becauseitisnoteasytomeasure thevalueof6・
Now,HBcallthatthecontm1peliodoftheservo motorcontmllerisTtimeslongerthanlhatofthe audiomiclopmcessorwhichhandlessignalsfrom lnicloPhonescmbeddediMhedunmny-head・ms meansthatlhevalueofW(A)isaN'ailableateach step,i・afbrVk・AssumhngthatthesoundsouIceis nxed,thefOllowingrClationholds:
;-鵜}三妄篝)-;{筈;三;{;+(7)
if"(ん+1)-w(ん)≠o
WhenthevalueoM(k)ateachMsavailable,the valueof6canbeidentinedbyusing(7)duringone samplingperiodofUleservomotorcontroUmThis updatinglawisimplelnentablesince(7)doesnot r己qUireth9valueofOd・
IMSIMULATION
InordertovalidatelheeffectivenessofUHepm- posedmethod,resultsofanumeIica1simUlationaIe showninthissection・
DynamicsoftherObotar己modenedasnrstPorder disc剛esystemasfbllow:
0(、T+k+1)=0.50(7,T十h)+0.5u(、T)
VAE[O…T-1].(8)
Letunitoftimeofthissystembe0.1second・It meanMhatthcstateO(片)issamp1edateaChO.l second・Hence,mesettlingtimeofthesystemis aboutO432secondAndtheinputsi印a】u(vZT)is conunandedateach5seconds(i、c、T=50).Audio signalg(ん)iSassumedtobedilcctlyavaiIab】eateach O1secondwilhoutusing(1).
0blisgivenasaslowsqumBwave:
鮴)={洲11W≦`三m0伽十m) (9)
whe"、isapositiVeintegenThecycleof帥egins
lOaudiosamplingstep(1second)priortod1atof contlO1cycle・TT1erehC,theservosystemreSponds totheChangeofOdwith4seconddclay・
InoldertocomPutethecontlo1inputtL(nT),
thevalueofK(冗T)withtheupdatingldw(7)is rcquired・Whenthembotstops,Cry(ん)=D(ん-1),
llLCoNTRoLScHEME
InmdertomakethecontroUerassimpleas possib1e,thefbllowinglinearoutlputfbedbaCkcontrol
sChemeisadopted:
駈皿(、T)=-K(洞T)w(、T),(4)
.wher已沌rcpIesents血enumberofthecontmlstep andTrep【esentstheperiodofthecontlol・THmeis sc2dedsuchthattheunitoftimeisequa1Iotheperiod ofaudiosignaL皿(,zT)andK(冗T)ICP[csentcontmI signaltOthemotorconnoUerandanadaptivefbed‐
backgainrBspcctiveUy・ItisassumedthatIhemotor
contmUercontmlstheo[ientationoflherubOt(0(ん))
suChlhat
O((冗十1)T)=0(,zT)+u(冗T).(5)
By(2),(3),(4)and(5)
0e((冗十1)T)=0。(河T)+u(泥T)
=,e(価)一K("T)w(、T)
=0e("T)-K(、T)処(72T)
=(1-K(,zT)5)ぬ(〃T).(6)
WhenO〈K(価)〈;,(6)showsthMe=O
isanasymptotica11ystableeqUiUMumpointatthe samplingrateT、Therefbre,thecontmlobjectiveis achievedwhenK(7,T)isasmallpositiveconstant・
Howevemtmaybetooconservativeto】etthevalue ofKbeaveIysmallpoSitiveconstant・Itmeans
【hesmanerthevalueofpositiveKis,thelonger thesystemtakestoconverge・InOrdertoimprove theperfblmanceofthesystenMhevalueofK(〃T)
mustbctunedadeqUately・Fromthcviewpointof
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(7)cannotbecomputedbecauseitsdenominator vaniShes・nlerBfbrMheupdatingIaw(7)ismodined
asfbllows:
K(k)= (10)
|鑑静鵬トD''三m)
LettheinitialvalueOfKbeK(O)=0.1.
InthissectioMnidealzdationbctweeny(k)and Oe(ん)whichismodeMby(3)isConSidered・The outputfmnctionismodemedas:
g(ん)=1000(0(k)-(9.(k)).(11)
ThefefbHMheoptimaM1ueofKis;=OOOL
FigUrc3showsnumeIicalresults・ThefirstEgure (Fig.3:a)showsthelcSponscofw(脂).At1hebegging ofthesmulatioM(k)variedwidelybutitColweIged toOastimCpassedn血swasbecausetheinitialva1ue oM,iMr(0)=Oユ,waslOOtimeslaIgerthanthe ,adequatevalueofiMndthesystemwasmstableat thebegimingof血esimmatioM(舟)convergedtoO fbralmostanykbumhevalueofitwasnotOdunng theperiOdfiomwhenOdChangedtowhencontrol inputwasissued.‐
NeXtfigU1℃3:bShows泥SponsesofO(ん)and8d(ん)
WithreSpecttotime・Sincelcsponsesbecamesteady periodiccyclesasitwasshowniniigure3:aresults ofthehrst300secondsa配showninfbnowing ligmreSmDisfigUI巳showMhatO(ん)trackedOlf(だ)
veHyweUthoughtheIBexistedadelaybecauseof phasediif垣IBncebetweeMdandu、Itisworthnoting thatO(脂)tmckeMbl(ん)withinafewcontru1step・
nMeSponseofK(A)iSShowniMgure3:cand thissupportsthatthesystelnsuitablyadaptedthe valueofK(ん)tolheOptimalvaluebyusingthe Updatinglaw(12)m1isimpliesthattheeffbctiveness oftheupdatinglaw(12)wasvalidated、Itisobvious
thatu(vDT)wasboundCdsinceX(ん)and9(ん)we泥
bounded(iigureM)
Thmughthissimulation,itisthoughtthatthe pmposedmethodcanbeeffeCtiVetoasimP1eaudio servosyStemevenifp[巳ciseinfbnnationofmicrC- phonesisnOtgivenα〃oアi、moughthCmodc1of mic1xmllonealray(3)or(11)consideI巴dinthispaper issimPle,thisappmachisapplicableasfaraMhe Idationbetween〃andOecom己spondingto(7)can beObtaincd・mere1ationisnot亜quiredtobea sca1areqUatiOn,、or・tobetherelationbetweenAth‐
StepandA;+lth-step・EvenmorccomplexmultistCp
易
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Hg3.ResultsofSimulation
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