Agent aided aircraft maintenance

AgentaidedaircraftmaintenanceOnnShehory,KatiaSycara,GitaSukthankarTheRoboticsInstituteCarnegie-MellonUniversityfonn,katia,[e-mail]27,1999AbstractAircraftmaintenanceisperformedbymechanicswhoarerequired,fornon-standarddiscrepancies,toconsultexpertengineersforrepairinstructionsandapproval.Inadditiontotheirownexperience,theseengineersrelyonexternalinformationsources,whichareofteninad-equatelyindexedandgeographicallydispersed.Thetimelyretrievalofthisdistributedinformationisessencialtotheengineers’abilitytodeviseandrecommendrepairproceduresinresponsetothemechan-ics’requests.Thisproblemdomainiswellsuitedforamulti-agentsystem:itconsistsofdistributedmulti-modalinformationwhichisneededbymultipleuserswithdiversepreferences.Inthispaper,wedescribeanimplementationofsuchasystem,usingtheRETSINAmulti-agentarchitecture.Suchanimplementationreinforcestheim-portanceofmulti-agentsystems,andinparticulartheusefulnessoftheRETSINAinfrastructureasabasisfortheconstructionofsuchsystems.i1IntroductionAgentaidedinformationretrievalanddecisionsupporthavebeenafocusoftheagentresearchcommunityforseveralyears.Althoughtheoriesandsimu-lationsofmulti-agentinformationretrievalsystemsabound,realapplicationsarescarce.Onereasonforthisscarcityisthelackofrealproblemdomainswhicharesucientlydistributed,richininformationandcomplexity,with-outbeingtoocomplex.Suchdomainswouldhavefacilitatedthedevelopmentofapplicationsystemsandallowedtheexaminationoftheapplicabilityandusefulnessofmulti-agenttechnologydevelopedinresearchlabs.1Inthispaperwepresentsuchanapplication.BasedonourexperiencewiththeRETSINAmulti-agentinfrastructure[7],weimplementedasystemtosolveanexistingreal-worldproblem.Specically,wedevelopedamulti-agentframeworkthatprovidesinformationretrievalandanalysisinsupportofdecisionmakingforaircraftmaintenanceandrepairintheU.S.AirForce.Althoughthesolutionwasdevelopedforaspecictypeofaircraft,theagentsandtheinteractionsamongthemweredesignedtoapplytoarangeofsimilarmaintenancescenarios.Maintenanceofcomplexvehiclessuchasaircraftandsea-craftisacom-plicatedtask.Usually,thistaskinvolvesseveralpeople,includingmechanics,inspectors,engineersandpossiblyotherexperts.Inaddition,theamountofinformationinvolvedintheprocessisverylarge.Thisinformationistypicallymulti-modalandavailableinmultiplestoragemedia(e.g.,hard-copyandelectronic).Commonly,theinformationisalsogeographicallydistributed.Amajorgoalofthemaintenanceprocessistoperformthemostappropriaterepairproceduresinthemostecientwayandintheshortesttime.Sincemaintenance-relatedprocessesrelyonrelevantinformation,comprehensiveandtimelyinformationdeliverytotheindividualsinvolvedinthemainte-nancecansignicantlybenettheprocess.Thepapersisorganizedasfollows:werstpresentthepropertiesoftheprobleminsection2.Then,insection3,wedescribetheRETSINAmulti-agentinfrastructure,whichweusedasthebasisforthedevelopmentofoursolution.Insection4wedescribethesolutionweprovidefortheproblemathand.Finally,insection5,wediscusstheadvantagesandthelimitationof1Suchresearchispresentedinmultiplepublications.Forexamples,surveysandpointerstoadditionalresearchreferto[2,3,4,5].1thesolutionandindicatefutureresearchdirections.2TheproblemAircraftmaintenanceintheU.S.AirForceisperformedatseveraldier-entlevels.Thebasicandintermediatelevelsareusuallyperformedatthebasewheretheaircraftisdeployed,whereasperiodic,comprehensivemain-tenanceisperformedatspcializeddepots.Inbothcases,maintenanceisacomplexprocesswhichinvolvesseveralprocedures,asdescribedbelow.Ini-tially,mechanicsinspecttheaircraftfordiscrepancies(andmayalsoreceivesuchinformationfrompilots).Foreachdiscrepancyhe/shends,theme-chaniclooks-upthetechnicalmanualsforastandardrepairprocedure.Incasethatsucharepairprocedureisfoundandtheresourcesandpartsre-quiredforitareavailable,themechanicproceedswiththerepairandlestherepairinformation.Incaseswherepartsarenotavailableortheyaretooexpensiveorrequiretoomuchtimeandadditionalmachinaryforre-placement,andincaseswhereaprocedureisnotprovidedinthetechnicalmanuals,amechanicneedstoconsultanexpertengineer.Theengineer,inturn,mayneedtoconsultexternalsourcesofinformation.Theseincludemanuals,historicalmaintenancedataandother,remotely-locatedexperts.Untilrecently,noautomationwasintroducedtotheconsultationprocessesofthisinformation-richenvironment,asdetailedbelow.Hard-copyrepairmanualsareused(bybothmechanicsandengineers),thussearchforrele-vantinformationmaybetimeconsumingandincomplete.Historicaldata(e.g.,recordsofprevioussimilarrepairs)isscarcelyused,sinceitisstoredinpaperformatwithnosearchmechanisms,usuallyonlykeptforshortperiodsoftime,andisdistributedalongremotelylocatedservicecenters.Experten-gineersmaybelocatedremotely,andtheiradviceisavailablebyvoiceorfaxmessages.Theseareusuallydelayedforhoursordays.Allofthesefactorscontributetoaslow,inecientinspectionandmaintenanceprocesses.Theinspection,consultationandrepairprocessconsistsofthefollowingsteps:1.Anaircraftarrivesatamaintenanceservicecenter,eitheratitshomebaseoratadepot(dependingonthetypeofmaintenancerequired).Inboth