铁路信号联锁系统中英文对照外文翻译文献Word文档格式.docx

铁路信号联锁系统中英文对照外文翻译文献Word文档格式.docx

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2Railwayssignalinterlockingsystem

2.1Functionsofsignalinterlockingsystem

Thebasicfunctionofsignalinterlockingsystemistoprotecttrainsafetybycontrollingsignalequipments,suchasswitchpoints,signalsandtrackunitsinastation,andithandlesroutesviaacertaininterlockingregulation.

Sincethebirthoftherailwaytransportation,signalinterlockingsystemhasgonethroughmanualsignal,mechanicalsignal,relay-basedinterlocking,andthemoderncomputer-basedInterlockingSystem.

2.2Architectureofsignalinterlockingsystem

Generally,theInterlockingSystemhasahierarchicalstructure.Accordingtothefunctionofequipments,thesystemcanbedividedtothefunctionofequipments;

thesystemcanbedividedintothreelayersasshowninfigure1.

Figure1ArchitectureofSignalInterlockingSystem

3Component-basedsafetycomputerdesign

3.1Designstrategy

Thedesignconceptofcomponent-basedsafetycriticalcomputerisdifferentfromthatofspecialcustomizedcomputer.OurdesignstrategyofSICisonabaseoffault-toleranceandsystemintegration.WeseparatetheSICintothreelayers,thestandardizedcomponentunitlayer,safetysoftwarelayerandthesystemlayer.Differentsafetyfunctionsareallocatedforeachlayer,andthefinalintegrationofthethreelayersensuresthepredefinedsafetyintegritylevelofthewholeSIC.Thethreelayerscanbedescribedasfollows:

（1）ComponentunitlayerincludesfourindependentstandardizedCPUmodules.Ahardware“SAFETYAND”logicisimplementedinthisyear.

（2）Safetysoftwarelayermainlyutilizesfail-safestrategyandfault-tolerantmanagement.TheinterlockingsafetycomputingofthewholesystemadoptstwooutputsfromdifferentCPU,itcanmostlyensurethediversityofsoftwaretoholdwithdesignerrorsofsignalversionandremovehiddenrisks.

（3）Systemlayeraimstoimprovereliability,availabilityandmaintainabilitybymeansofredundancy.

3.2Designofhardwarefault-tolerantstructure

Asshowninfigure2,theSICoffourindependentcomponentunits（C11,C12,C21,C22）.Thefault-tolerantarchitectureadoptsdual2vote2（2v2×

2）structure,andakindofhigh-performancestandardizedmodulehasbeenselectedascomputingunitwhichadoptsIntelXScalekernel,533MHZ.

TheoperationofSICisbasedonadualtwo-layerdatabuses.ThehighbusadoptsthestandardEthernetandTCP/IPcommunicationprotocol,andthelowbusisControllerAreaNetwork（CAN）.C11、C12andC21、C22respectivelymakeupoftwosafetycomputingcomponentsIC1andIC2,whichareof2v2structure.Andeachcomponenthasanexternaldynamiccircuitwatchdogthatissetforcomputingsupervisionandswitching.

Figure2HardwarestructureofSIC

3.3Standardizedcomponentunit

Aftercomponentmoduleismadecertain,accordingtothesafety-criticalrequirementsofrailwaysignalinterlockingsystem,wehavetodoasecondarydevelopmentonthemodule.Thedesignincludespowersupply,interfacesandotherembeddedcircuits.

Thefault-tolerantprocessing,synchronizedcomputing,andfaultdiagnosisofSICmostlydependonthesafetysoftware.Herethesafetysoftwaredesignmethodisdifferingfromthatofthespecialcomputertoo.Fordedicatedcomputer,thesoftwareisoftenspeciallydesignedbasedonthebarehardware.Asrestrictedbycomputingabilityandapplicationobject,aspecialschedulingprogramiscommonlydesignedassafetysoftwareforthecomputer,andnotauniversaloperatingsystem.Thefault-tolerantprocessingandfaultdiagnosisofthededicatedcomputeraretightlyhardware-coupled.However,thesafetysoftwareforSICisexotericandlooselyhardware-coupled,anditisbasedonastandardLinuxOS.

Thesafetysoftwareisvitalelementofsecondarydevelopment.ItincludesLinuxOSadjustment,fail-safeprocess,fault-tolerancemanagement,andsafetyinterlockinglogic.ThehierarchyrelationsbetweenthemareshowninFigure4.

Figure4SafetysoftwarehierarchyofSIC

3.4Fault-tolerantmodelandsafetycomputation

3.4.1Fault-tolerantmodel

TheFault-tolerantcomputationofSICisofamultilevelmodel:

SIC=F1002D（F2002（Sc11,Sc12）,F2002（Sc21,Sc22））

Firstly,basiccomputingunitCi1adoptsonealgorithmtocompletetheSCi1,andCi2finishestheSCi2viaadifferentalgorithm,secondly2outof2（2oo2）safetycomputingcomponentofSICexecutes2oo2calculationandgetsFSICifromthecalculationresultsofSCi1SCi2,andthirdly,accordingthestatesofwatchdogandswitchunitblock,theresultofSICisgottenviaa1outof2withdiagnostics（1oo2D）calculation,whichisbasedonFSIC1andFSIC2.

Theflowofcalculationsisasfollows:

（1）Sci1=Fci1（Dnet1,Dnet2,Ddi,Dfss）

（2）Sci2=Fci2（Dnet1,Dnet2,Ddi,Dfss）

（3）FSICi=F2oo2（Sci1,Sci2）,（i=1,2）

（4）SIC_OutPut=F1oo2D（FSIC1,FSIC2）

3.4.2Safetycomputation

Asinterlockingsystemconsistsofafixedsetoftask,thecomputationalmodelofSICistask-based.Ingeneral,applicationsmayconformtoatime-triggered,event-triggeredormixedcomputationalmodel.Herethetime-triggeredmodeisselected,tasksareexecutedcyclically.TheconsistencyofcomputingstatesbetweenthetwounitsisthefoundationofSICforensuringsafetyandcredibility.AsSICworksunderalooselycoupledmode,itisdifferentfromthatofdedicatedhardware-coupledcomputer.SoaspecializedsynchronizationalgorithmisnecessaryforSIC.

SICcanbeconsideredasamultiprocessordistributedsystem,anditscomputationalmodelisessentiallybasedondatacomparingviahighbuscommunication.First,ananalyticalapproachisusedtoconfirmtheworst-caseresponsetimeofeachtask.Toguaranteethedeadlineoftasksthatcommunicateacrossthenetwork,theaccesstimeanddelayofcommunicationmediumissettoafixedpossiblevalue.Moreover,thecomputationalmodelmustmeetstherealtimerequirementsofrailwayinterlockingsystem,withinthesystemcomputingcycle,wesetmanycheckpointsPi（i=1,2,...n）,whicharesmallenoughforsynchronization,andcomputationresultvotingisexecutedateachpoint.ThesafetycomputationflowofSICisshowninFigure5.

Figure5SafetycomputationalmodelofSIC

4.Hardwaresafetyintegritylevelevaluation

4.1SafetyIntegrity

Asanauthoritativeinternationalstandardforsafety-relatedsystem,IEC61508presentsadefinitionofsafetyintegrity:

probabilityofasafety-relatedsystemsatisfactorilyperformingtherequiredsafetyfunctionsunderallthestatedconditionswithinastatedperiodoftime.InIEC61508,therearefourlevelsofsafetyintegrityareprescribe,SIL1～SIL4.TheSIL1isthelowest,andSIL4highest.

AccordingtoIEC61508,theSICbelongstosafety-relatedsystemsinhighdemandorcontinuousmodeofoperation.TheSILofSICcanbeevaluatedviatheprobabilityofdangerousperhour.TheprovisionofSILaboutsuchsysteminIEC61508,seetable1.

Table1-SafetyIntegritylevels:

targetfailuremeasuresforasafetyfunctionoperatinginhighdemandorcontinuousmodeofoperation

SafetyIntegritylevel

HighdemandorcontinuousmodeofOperation

（ProbabilityofadangerousFailureperhour）

4≥10-9to＜10-8

3≥10-8to＜10-7

2≥10-7to＜10-6

1≥10-6to＜10-5

4.2ReliabilityblockdiagramofSIC

AfteranalyzingthestructureandworkingprincipleoftheSIC,wegetthebockdiagramofreliability,asfigure6.

Figure6BlockdiagramofSICreliability

5.Conclusions

Inthispaper,weproposedanavailablestandardizedcomponent-basedcomputerSIC.Railwaysignalinterlockingisafail-safesystemwitharequiredprobabilityoflessthan10-9safetycriticalfailuresperhour.Inordertomeetthecriticalconstraints,fault-tolerantarchitectureandsafetytacticsareusedinSIC.Althoughthecomputationalmodelandimplementationtechniquesarerathercomplex,thephilosophyofSICprovidesacheerfulprospecttosafetycriticalapplications,itrendersinasimplerstyleofhardware,furthermore,itcanshortendevelopmentcycleandreducecost.SIChasbeenputintopracticalapplication,andhighperformanceofreliabilityandsafetyhasbeenproven.

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模块化安全铁路信号计算机联锁系统

1概述

信号联锁系统是保证交通安全、提高铁路运输效率的关键设备。

长期以来，在联锁系统中采用的核心控制计算机是特定的高档安全计算机，例如，西门子的SIMIS、日本信号的EI32等。

随着电子技术的飞速发展，定制的安全计算机面临着严重的挑战，例如：

高的开发成本、可用性差、弱可扩展性、和缓慢的技术更新。

为了克服高档特定计算机的缺点，美国国防部提出：

我们应该采用商业标准，来取代军事准则和满足客户需要的标准。

与