benefits of FMEA in the development process of sof

1/6SoftwareFMEAOpportunitiesandbenefitsofFMEAinthedevelopmentprocessofsoftware-intensivetechnicalsystemsOliverMäckelSiemensAGSimulationandRiskManagementCTPP281730MünchenTechnicalsystemsareprevalentinmanyareasofoursociety.Nowadaystheyoftenincludeaconsiderableamountofsoftware.Identificationandavoidanceoftechnicalrisksisofmajorimportanceinthedevelopmentofthesesoftware-intensivetechnicalsystems.ApowerfulanalysistechniqueinthedevelopmentprocessfortechnicalsystemsistheFailureModeandEffectsAnalysis(FMEA).Thistechniquehasprovedveryeffectiveinavoidingfailuresinmanyareasofindustry.However,thereistodatenowidespreaduseoftheFMEAtechniqueforsoftware-intensivesystems.ObjectivesandbenefitsofcarryingoutFMEAsonsoftwarewillbediscussedalongwithadvantages,areasofapplication,weaknessesandconstraints.IntroductionTechnicalsystemsareprevalenttodayinmanyareasofoursociety.Duetoeconomicrationalizationandthenecessitytomeetincreasedrequirementsregardingperformanceandergonomicsanever-growingnumberofcomplextasksarebeingautomated.Anincreasingdependenceofsocietyonthesafeandreliableoperationofthesesystemsistheconsequence.Asanexample,afaultyticketvendingmachineiscertainlyanuisancefortheuserandmayalsoleadtosubstantivedamage.Theunintentionalinflationofanairbagwithoutanyunderlyingvehiclecollisionontheotherhandcouldleadtoseriousinjuryorevenfatalities.Thecatastrophicfailureofanon-boardaeroplanecomputercouldleadtogreatlossoflife.Todaytechnicalsystemsoftencontainconsiderableamountsofsoftware,whichalreadyconstitutesanessentialpartofthesystem.Itisafactthatnewmotorvehiclesthesedayscontainnearly50computersystems[1].Extremelyhighsafetyandreliabilitylevelsarerequiredofthesemainlysoftware-intensivesystems.Examplescanbefoundbyconsideringcostlycapitalequipment,especiallyaeroplanesandrailvehicles.Highsafetyandreliabilitylevelsarealsorequiredformass-producedproductssuchasmotorvehiclecomponents,forindustrialautomationequipmentetc[2].Theserequirementsnecessitate,especiallyundertheconsiderationofincreasedtime-to-marketandcost-to-marketpressure,arisk-orienteddevelopmentforsoftware-intensivetechnicalsystems.FailureModeandEffectAnalysisTheFailureModeandEffectsAnalysis(FMEA)[3,4]isanimportantanalysistechniqueinthedevelopmentprocessoftechnicalsystems.ItwasdevelopedbyNASAintheUSA[7]intheearlysixtiesfortheApolloProject.Intheautomobileindustryitisstandardprocedureforplanninganddevelopment[8].Inotherareasofindustry[9]FMEAcanbefoundasamethodologicalcomponentofqualitymanagement.TheFMEAisacknowledgedtotheindustryinmanyranges[8,9,10].InapreventingwaytheFMEAtakesfailurebehaviourandcausesintoconsiderationandevaluatesassociatedriskswithrespecttooccurrence,severityanddetection.Thesimplicityandefficiencyofthetechniquehasproveditsvalueand,2/6furthermoreitisrecommendedinrelevantStandards[5,6]forthedevelopmentofsafety-criticalsystems.FMEAforsoftware(SW-FMEA)-GoalsandBenefitsInrelationtohardwarefailurebehaviourandhumanerroritisgraduallybecomingmoreimportanttoviewthefailurebehaviourofsoftwareanditseffects.Thismustbetakenintoaccountbythedevelopmentoftechnicalsystems.FMEAisanestablishedtechniquetoavoidfailuresintechnicalsystems.AtimelyperformedFMEAisriskmanagementinsteadofcrisismanagement[15].Intheearlyphasesofsoftwaredevelopmentwherethecostsforchangesaresmall(Fig.1)andwillingnesstochangeishigh,itmakessensetoidentifyandavoidfailuresinapreventiveway.Byevaluatingtheindividualrisksadifferentiationbetweenhighriskandlowriskcomponents,modulesandfunctionscanbeachieved.Thismakesarisk-orienteddevelopmentofsoftware-intensivesystemspossible.relativenumberoffaultsrelativnumberofdetectedfaultsCostsforfaultcorrectionperfault(TDM)AnalysisDesignCodingModul-testSystemtestField10%40%50%3%5%7%25%50%10%0,50,50,52,06,025,0Fig.1:Faultoccurrence,faulteliminationandfaultcorrectioncostsinsoftwaredevelopment[15]ASW-FMEAistheconsitentcontinuationoftheFMEAofthesystem(systemFMEA:SFMEA)foranalyzingsoftware-intensivecomponentsoftheconsideredsystem.TheirresultsfindtheirwaybacktotheFMEAofthesystem.However,theFMEAtechniqueisnotyetwidelyusedforsoftware-intensivesystems.Generaluseoftheseanalysesinthedevelopmentoftechnicalsystemsismoreimportantthemoretherequirementsfortime-to-marketandcost-to-marketincrease.SW-FMEA!duringthedesignofthesystemaspartoftheFMEAofthesystem!duringthesoftwaredesignfortheidentificationofcriticalfunctions!duringthesoftwaredesignfortheidentificationofcriticalmodulsFig.2:WhenshouldaSW-FMEAbeperformed?TheSW-FMEAisasystematic,structuredtechniqueforthereviewofthesoftwarearchitectureorthesoftwaredesignwithrespecttotechnicalrisks(e.g.safety,reliabilityoravailability).TheSW-FMEAisusedforknowledgetransfer.Theknowledgeofdifferentdepartments,likeforexamplesystemdevelopment,softwaredevelopment,testandservice,isbroughttogetherandusedduringtheFMEAintheteam.Sothenumberofviewsonorintoasystemandasystem'ssoftwareincreasesitself.3/6ProcedureTheSW-FMEAiscarriedoutasasupplementtoaFMEAofasystem.Itisusedforarchitectureordesignreviewduringthedevelopment.TheSW-FMEAshouldbeperformedbeforetheimplementationofthesoftware.Itmayno