Analysis and Verification Challenges Cyber-Physical Transpor(2)

混合系统建模与验证

indicatethattherisingcomplexityoftransportationsystemsmakesitimpossibleforhumanstounderstandtheire ectsandsidee ectsunderallcircumstances.Thisincludes awsinthewarningsystemthatledtothefrontaltraincollisioninChatsworth2008,de cienciesinsomeadaptivecruisecontrollersforcarsfrom2005,andunfortunatehuman-controller¨interactionscausingthefatalmid-aircollisioninUberlingenin2002.

SeverallargeresearchprojectshavebeenlaunchedalreadyinEurope,includingAVACS,ARTIST-2,HYCON,Minalogic,andSPEEDS.WeneedmajorinitiativesfortheUStotakealeadinadvancingthestateoftheartinCPSanalysis.

2ImportantResearchChallengesforCPSTransportation

Theincreasingneedforanalysistechniquesthatscaletotoday’stightlyintegratedtrans-portationcontrolimposesseveralresearchchallengesforCPSanalysisandveri cation.ScalableAnalysiswithrespecttoComplexityandDimensionality:Themostpress-ingneedtodayareanalysistechniquesthatactuallyscaletothefullcomplexityofrealap-plications.Thetwomostfundamentallimitationstodayarethatmostanalysistechniquescanonlyhandlefairlylimitedclassesofsystemdynamics(usuallyonlylinearorevencon-stantdynamics)andthatthedimensionofthecontinuousstatespacetheycanhandleislow(around3-8).Mostapplicationsaregovernedbymorecomplicateddi erentialequations(e.g., ightdynamics)andhavesubstantiallyhigherdimensions(modelsoftheenvironment).Beyondanydoubt,themajorchallengeforhandlingrealistictra csystemsistodeveloptechniquesthatscalereliablybothinthedimensionandcomplexityofthesystemdynamics.Eventoday’shighprecisionanalyseswouldalreadyneednon-lineardynamicsforhundredsofvariables.Iffutureresearchadvancesarenotabletosolvethescalabilityproblem,thegrowingcomplexityofCPScannotbemanagedanymore.Withoutsigni canttechnologicaladvances,weareconvincedthatathoroughsafetyanalysiswillneverbecomepossible!Large-scaleVeri cationArchitecturesforCyber-PhysicalSystems:Tospeeduptheveri cationprocesswithgoodscalabilitypropertiesforindustrialsettings,weenvisionthedevelopmentoflayeredarchitectures.Ratherthanverifyingeachnewtransportationsystemfromscratch,weconsideritmoreeconomicandprobablyevenmoretractabletodevisedomain-speci cveri cationframeworks.Inmuchthesamewayas,e.g.,carsaredesignedasinstancesofaproductfamily,theirsafetyandfailure-robustnessanalysisshouldbeconductedasaspecialinstanceofthegeneralveri cationframeworkforgroundtransportation.Forsuchaframework,acommonparametricsetupcanthenbepre-veri edonceandforall.Eachdesignofaspeci ctra cagentwouldthenonlyneedtobere-analyzedwithrespecttoacorrectinstantiationofthemoregeneralveri cationpattern.Ultimately,weconceivetheformingofVeri cationEngineeringasanewdisciplinedevotedtothesystematicdevelopmentanduseofcorrespondingdomain-speci cveri cationplans.

DynamicNetworksofCyber-PhysicalSystems:Adi erentresearchchallengeresultsfromtheoverwhelmingincreaseofwirelesscommunicationintransportationandtheresult-ingconsequencesfortheoverallsystemscope.AlreadyincurrentimplementationsofETCS,GSM-basedwirelessistheexclusivecommunicationchannelforestablishingconsentastowhichtrainisallowedtomovehowfaronwhichtrack.Similarly,theupcomingCAR2CAR