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UseofVoiceRecognitionforControlofaRoboticWeldingWorkcellABSTRACT:Thispaperdescribesworkunderwaytoevaluatetheeffectivenessofvoicerecognitionsystemsasanelementinthecontrolofaroboticweldingworkcell.Factorsbeingconsideredforcontrolincludeprogrameditoraccesssecurity,Preoperationchecklistrequirements,weldingprocessvariablecontrol,androbotmanipulatormotionoverrides.Inthelattertwocategories,manualvocalcontrolisbeingcomparedagainstmanualtactilecontrolandfullyautomaticcontrolintermsofspeedofresponse,accuracy,stability,reliability.Andsafety.IntroductionVoicerecognitiontechnologyisnowrecognizedasapotentialmeansforeasingtheworkloadofoperatorsofcomplexsystems.Numerousapplicationshavealreadybeenimplemented,areinvariousstagesofdevelopment,orareunderconsideration.Theseincludedataentry,controlofaircraftsystems,andvoiceidentificationandverificationforsecuritypurposes.Voicecontrolhasalsobeenproposedforuseaboardthespacestation.Oneprimeareaforapplicationwouldbecontrolofsomefunctionsofrobotsusedforintraandextravehicularinspection,assembly,repair,satelliteretrieval,andsatellitemaintenancewhenacrewmemberisservinginasupervisorycapacityorthesystemisoperatinginateleoperationmode.Voicecontrolofsensorsandprocessvariableswouldfreethecrewmember’shandsforothertasks,suchasdirectcontroloroverrideofthemanipulatormotion.Similarly,theworkloadassociatedwithcontrolofmanyonboardexperimentscouldbeeasedthroughtheuseofthistechnology.Thispaperdescribestheapplicationofvoicerecognitionforcontrolofaroboticweldingworkcell.Thisisacomplexsysteminvolvinginputsfrommultiplesensorsandcontrolofawidevarietyofrobotmanipulatormotionsandprocessvariables.Whilemanyfunctionsareautomated,ahumanoperatorservesinasupervisorycapacity,readytooverridefunctionswhennecessary.Inthepresentinvestigation,acommerciallyavailablevoicerecognitionsystemisbeingintegratedwitharoboticweldingworkcellatNASAMarshallSpaceFlightCenter,whichisusedasatestbedforevaluationanddevelopmentofadvancedtechnologiesforuseinfabricationoftheSpaceShuttleMainEngine.Inthesystemunderdevelopment,somefunctionsdonotyethaveautomaticclosedloopcontrol,thusrequiringcontinuousmonitoringandreal-timeadjustmentbythehumanoperator.Presently,theseovemdesareinputtothesystemthroughtactilecommands(;.e..pushingbuttons.turningknobsforpotentiometers,oradjustingmechanicaldevices).Sincetheoperatormonitorstheprocessprimarilyvisually,hemusteitherlookawayfromtheprocesstofindtheproperbuttonorknoborrelyon“muscularmemory”muchasatouch-typistdoes.Inthefirstcase,thetimeofresponsetoadeviantconditionmaybeexcessive.Inthesecondcase,thereisanincreasedprobabilityofasecondaryerrorbeingintroducedbytheoperator.Avoicerecognitionsystemcouldreducetheresponsetimerequiredfromtheoperator.Theprobabilityofpushingthewrongbuttonshouldsimilarlybereduced.Also,operatorfatigueshouldbeminimized.Sincetheoperatorcancontinuouslymonitortheprocessduringoverrideinput,theeffectofthechangecanbeobservedmorequickly.Thus,ifthedesiredvalueisexceededandreversecorrectionisrequired,itshouldbeaccomplishedmorequickly,allowinglessovershoot.Thisreductioninoscillationaboutthedesiredvaluemakesthesystemmorestable.Anotherfactorthatcanbeimprovedisoperatorsafety.Inasafety-criticalsituation,therobot’soperationcanbehaltedimmediatelybyuseofthe“emergencystop,’’orE-stop,mode,whichisinitiated,conventionally,bydepressingalargebutton.Ifanoperatorinadvertentlyfindshimselfinahazardoussituation,itmaybenecessaryforhimtoinitiatetheE-stopsequence.Shouldtheoperatornotbewithinreachofthebutton,however,hemaybeunabletotakethenecessaryaction,and,asaresult,couldsufferseriousinjury.Havingthecapabilityofstoppingtherobotbyissuingavoicecommandcouldsignificantlyimprovetheoperator’ssafetybyenablinghimtostoptherobotevenwhennotwithinreachoftheE-stopbutton.Manualcorrectionsareoccasionallyrequiredtoadjustthelocationatwhichtheweldfillerwireenterstheweldpool.Properentrylocationisabsolutelycriticaltosoundweldquality.Adjustmentsaremadeeitherbymanuallyadjustingmechanismsthatholdthewirefeedguidetubeorbyissuingtactilecommandstoaservomechanism.Useofavoicerecognitionsystemcouldeliminatetheneedfortheoperatortoplacehishandwithintheworkingenvelopeoftherobotendeffectoror,ifservomechanismsareemployed,couldimprovespeedofresponseandstability.Anotheraspectofrobotoperationinanindustrialenvironmentthatisveryimportantisthesecurityofaprogrameditingcapabilityofthesystem.Undernocircumstancesshouldanyunauthorizedpersonbeabletoenterthisprogrammingmodeandaltertherobot’sprogram.Avoicerecognitionsystemcanprovidethenecessarysecuritybyallowingaccessonlyforindividualswhoareauthorizedandwhosevoicescanbeidentifiedbythesystem.BackgroundRoboticweldingisunderdevelopmentbyNASAandRocketdynefortheautomationofweldsontheSpaceShuttleMainEnginethatarepresentlymademanually.Theprogrammabilityofarobotcanreducethepercentageofweldingdefectsthroughacombinationofconsistencyandrepeatabilityunattainablebyitshumancounterparts.Todothis,therobotisprogrammedtoanominalweldpathandlevelofweldprocessparameters(i.e.,current,travelspeed.voltage,wireadditionrate).Someadjustmentofthe