单片机类设计英文翻译.docx

单片机类设计英文翻译.docx

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单片机类设计英文翻译

单片机类毕业论文设计

英文资料翻译

Amodeling-basedmethodologyforevaluatingtheperformanceofareal-timeembeddedcontrolsystem

KlemenPerko,RemyKocik,RedhaHamouche,AndrejTrost

ABSTRACT

Thispaperpresentsamodelling-basedmethodologyforembeddedcontrolsystem（ECS）design.Here,insteadofdevelopinganewmethodologyforECSdesign,weproposetoupgradeanexistingonebybridgingitwithamethodologyusedinotherareasofembeddedsystemsdesign.Wecreatedatransformationbridgebetweenthecontrol-schedulingandthehardware/software（HW/SW）co-designtools.Bydefiningthisbridge,weallowforanautomaticmodeltransformation.Asaresult,weobtainmoreaccuratetiming-behavioursimulations,consideringnotonlythereal-timesoftware,butalsothehardwarearchitecture’simpactonthecontrolperformance.Weshowanexamplewithdifferentmodel-evaluationresultscomparedtorealimplementationmeasurements,whichclearlydemonstratesthebenefitsofourapproach.

©2011ElsevierB.V.Allrightsreserved

KEYWORDS:

Modeling,Modeltransformations,Embeddedcontrolsystemsdesign,Real-timesystems

1.Introduction

Embeddedcontrolsystems（ECSs）areubiquitousnowadays.Theyareusedinabroadspectrumofapplications,fromsimpletemperaturecontrolinhouseholdappliancestocomplexandsafety–criticalautomotivebrakesystemsoraircraftflightcontrolsystems.Differentapplicationshavedifferentdemandswithregardstothereal-timeexecution,controlperformance,energyconsumption,price,etc.,oftheECSbeingused.Moderntechnologiesforhardware（HW）andsoftware（SW）designprovideavarietyofpossibilitiesfordesigningECSs（e.g.,distributedandnetworkedHW,multi-processorsystems,avarietyofSWcontrolalgorithmsandreal-timeoperatingsystems（RTOSs）,etc.）[1].ItiscommonlyacknowledgedthatthedesigningandverifyingofreliableandefficientECSsforaparticularapplicationarechallengingtasks.

1.1.Traditionalcontrol-systemdesign

TheaimofdesigninganECSistobuildacomputingsystemthatisabletocontrolthebehaviorofaphysicalsystem,e.g.,aplant.Suchaplantismadeupofinterconnectedmechanical,electricaland/orchemicalelements.AtypicalECSconsistsofelectronicsensorsfordataacquisitionfromtheplant,acomputingsystemforprocessingthecontrolalgorithm,andelectronicactuatorstodrivetheplant.

TheECSdesignprocessinvolvesdifferentactorsandareasofexpertise（controltheory,signalprocessing,real-timeSWandHWengineers）.Eachoftheseengineersisfamiliarwiththeirownmodelinglanguages,models,designtools,etc.Thisheterogeneityintroducescutsinthedesignprocess.Modeltransformationsareneededbetweeneachdesignstep;however,theyareoftencarriedoutmanuallyand,asaresult,arepronetomistakesandsubjecttointerpretation,whichofcoursedependsontheskillofthedesigner.ThetraditionalformofECSdesignisperformedintwoseparateddomains–thecontrolSWdomainandtheHWdomain–usingspecificdesigntoolsandtheirrespectivesystemmodels.Inthefirstdomain,controlengineersdefinethecontrollawsandtheSWengineerswritethecodethatexecutestheoperationsrequiredbythecontrollaws.Aso-calledcontrol-schedulingco-designisperformed.Decisionsmadeinthereal-time（RT）softwaredesignaffectthecontroldesign,andviceversa.Forinstance,differentSWschedulingpolicieshavedifferentimpactsonthelatencydistributionsinthecontrolloopsand,consequently,ontheirperformance.Also,thecontrol-loopperformancedirectlyaffects（byconstraining）theSWexecutionparameters（i.e.,samplingperiods,task-executionjitter,etc.）.

IntheseconddomaintheHWengineersdesignanHWplatformthatwillexecutethecontrolSW.Theconnectionsofallthesensorsandactuatorstotheplatformaremadeviatheavailablecommunicationchannels.However,becausetheHWplatformisdesignedseparately,controlengineerscannotestimateitsimpactonthecontrol-loopperformance.Forinstance,thedatafromsensorsandtoactuatorscanpassthroughoneormorecommunicationchannels.AHWengineercan,ingeneral,choosefromamongavarietyofcommunicationprotocols,andeachtypeintroducesdifferentlatenciesandjitter,whichthereforeaffectstheSWexecution.Thecontrolengineercannot,however,evaluatetheeffectoftheselatenciesbeforethesystemisactuallyimplemented.Hence,thedesiredperformanceofthesystemmaynotbeachieved,anditisnecessarytochangeandtunethecontrollaws（calibrationphase）inordertocompensatefortheimpactofthesecommunicationandexecutiondelays.Thefactthatthecalibrationhastobeperformedonanactualplantcanbeveryexpensiveandtime-consuming,especiallywhenthedesiredperformancecannotbeachievedusingthecurrentHWplatformandaredesignisrequired.AnothershortcomingoftraditionalECSdesignistheinabilityofcontrolandSWengineerstoexploitsomeoftheadvantagesofferedbymodernHWtechnologies.Forinstance,controlloopsrunninginparallel,insteadofthetraditionalsequentialexecution,couldgivebetterperformance.Parallelexecutioncanbeachievedwiththeuseofmulti-processorordistributedplatforms.

ModernECSdesigntechniquesrelyheavilyonsystemmodeling,whichprovidesameanstoexaminehowvariouscomponentsworktogetherandtoestimatetheimpactoftheECS’simplementationoncontrolperformancebeforeitisactuallyimplemented.Thismakesitpossibletocorrecttheinitialcontrollawsinordertocompensatefortheimplementationimpactsearlyinthedesigncycle.Anotherimportantaspectofmodelingistheabilitytoexploredifferentpossiblesystemimplementations（design-spaceexploration）.AppropriatemodelingcansignificantlyshortenthedesigncycleofanECS[2].

Toovercometheproblemsintroducedbytheheterogeneityofdesignmodelsandtools,differentmethodologiesandtoolsweredeveloped[3].ThesemethodologiesusuallyprovideameanstocreateauniformECSmodel,simulateandevaluateitsbehavior,formallytransformittowardsanimplementation,etc.

1.2.Proposedcontrolsystemdesign

ToimproveandacceleratethetraditionalECSdesignweproposethemergingoftheseseparateddomains.Onthebasisofthismerging,alltheactorsinthedesignprocesscouldbettercollaborateandexchangetheirdataduringthedesignprocess,theycoulddoamorethoroughdesign-spaceexplorationandthedesigncyclecouldbemadesignificantlyshorter.InsteadofdevelopinganewmethodologyforECSdesign,weproposetoupgradethetraditionalSW-basedcontrol-systemdesignapproachwithefficientmodelinganddesignoftheHWplatforms.Recently,severalmethodologieshavebeendevelopedthatconcernHW/SWco-design.ThesemethodologiesenabletheefficientdesignofSWandHWonembeddedsystemsintermsofSWexecutionspeed,HWresourcesusage,systemflexibility,futureupgradeability,finaldesigncosts,etc.Weproposecreatingaformalbridgebetweentheexistingtoolsforcontrol-schedulingco-designandHW/SWco-design.Thisbridgemakespossiblemodeltransformationsandtheexchangeofsimulationresultsbetweentoolsforcontrol-schedulingco-designandHW/SWco-design.

Thebridgeisbasedonaformaltransformationofmodelsbetweendifferentdesigntools.Ourfoundationforthecontrolschedulingco-designmethodologyisworkpresentedin[4]anditsassociatedtool,MoDEST,whichispresentedin[5].ForthepurposeofHW/SWco-designwehaveselectedthemethodologypresentedin[6]withitsassociatedabstract-systemmodelingtool,ASyMod,whichispresentedin[7].Withthebridgeweareabletoobtainmoreaccuratecontrol-performanceevaluationsconsideringarchitecturaldetailsandeventhepossibilitytostudymixedHW/SWimplementationsofthecontrolsystem.Evaluatingtheimpactofimplementationintheearlydesignstagesreducesthenumberofdesign-lifecycleiterationsandshortensthetimeneededforafinalcalibrationofthecontrollaws.

Inthenextsectionwepresenttherelatedmethodologies,followedbyshortdescriptionsoftheMoDESTandASyModtoolsandtheirmetamodels.InSection3wedescribetheformalrulesformodeltransformationandtheimplementationofthebridge.InSection4,twoexamplesofanembeddedcontrollerarepresented.Bycomparingsimulationresultstomeasurementsonarealimplementedsystem,weshowthebenefitsofourapproach.Finally,thepaperisconcludedinSection5.

1.3.Relatedmethodologiesandtools

TheincreasingneedtooptimizeECSsintermsoftheircontrolperformance,RTconstraintsandcostefficiencyhasledtolimitedcomputationalresourcescombinedwiththeirefficientexploitationandhas,asaconsequence,encouragedtheemergenceofnewresearchareas.

Domain-specifictoolsforcontrol-schedulingco-designhavebeendevelopedrecently.Thesetoolssupportimplementationmodelingandanalysisintermsofcontrolperformance.SeveralofthetoolsarebasedonMatlab,whichistraditionallyusedbycontrolengineersforthedesignofcontrollaws.TheAIDA[8]toolsetisamodel-basedenvironmentforthedesignandanalysisofcontrolsystems,usedeitherinstand-aloneformorwithMatlab.Thetoolsetsupportsthemodelingofcontrol-functionexecutionondistributedHWcomponentscontainingmulti-processorsandcommunicationslinks.Theeffectsofthecontrolalgorithm’simplementationoncontrolperformancecanbeanalyzed.Jitterbug[9]isaMatlab-basedanalysistoolforcomputingaquadraticperformancecriterioninlinearcontrolsystemsundervarioustimingconditions.UsingJitterbug,thesensitivityofcontrolsystemstodelays,jitterandotherinterferencescanbestudied.TheeffectsofdifferentSWimplementati