外文翻译原文-基于单片机的火灾探测和监控系统

Multiplesingle-chipmicrocomputerapproachtofiredetectionandmonitoringsystemA.J.AI-Khalili,MSc,PhDD.AI-Khalili,MSc,PhDM.S.Khassem,MScIndexingterm:Hazards,Design,PlantconditionmonitoringAbstract:Acompletesystemforfiredetectionandalarmmonitoringhasbeenproposedforcomplexplants.Thesystemusesmultiplesinglechiparchitectureattachedtoapartyline.Thecontrolalgorithmisbasedonatwo-levelhierarchyofdecisionmaking,thusthecomplexityisdistributed.Acompletecircuitdiagramisgivenforthelocalandthecentralstationwithrequirementsforthesoftwarestructure.Thedesigniskeptingeneralformsuchthatitcanbeadaptedtoamultitudeofplantconfigurations.Itisparticularlyshownhownewdevelopmentsintechnology,especiallyCMOSsinglechipdevices,areincorporatedinthesystemdesigntoreducethecomplexityoftheoverallhardware,e.g.bydecomposingthesystemsuchthatlowerlevelsofhierarchyareabletohavesomeautonomyindecisionmaking,andthusamorecomplexdecisionissolvedinasimpledistributedmethod.1IntroductionRegulatoryrequirementsformosthighriskplantsandbuildingsmandatetheinstallationoffiredetectionandwarningsystemsforallsensitiveareasoftheplantorthebuilding.Mostfirecodesstatetherequirementformonitoringandcontrolspecificallyrelatedtoatypeofaplantorbuildingsuchaschemicalplants,petroleum,nuclearplants,residentialhigh-risesetc.Ageneralconclusionofthesecodescanbespecifiedasthefollowingrequirements:(a)Thesourceofalldetectorsignalsshouldbeexactlyidentifiablebythecentralstation(b)Anextrapathofcommunicationbetweenthecentralstationandalllocalcontrollers(c)Directmeansofcontrolofalarmandcentralequipmentbythecentralstation(d)Meansofcommunicationbetweenthecentralstationandthefiredepartment(e)Availabilityofemergencypowersupply.Thecodesusuallyalsospecifythetypesandfrequencyoftestsforallequipment.Afiredetectionandalarmsystemisacombinationofdevicesdesignedtosignalanalarmincaseofafire.Thesystemmayalsoaccomplishfancontrol,firedoorholdorrelease,elevatorrecall,emergencylightingcontrolandotheremergencyfunctions.Theseadditionalfunctionssupplementthebasicsystemwhichconsistsofdetectionandalarmdevicesandcentralcontrolunit.Technologyhasaninfluenceonsystemarchitecture.Whentechnologychanges,thearchitecturehastoberevisedtotakeadvantageofthesechanges.Inrecentyears,VLSItechnologyhasbeenadvancingatanexponentialrate.FirstNMOSand,inthelastyearortwo,CMOSchipshavebeenproducedwiththesamepackingdensitywithmoregatesperchipyetatalowerpowerconsumptionthanNMOS.Surelythischangeintechnologymustaffectourdesignofhardwareatboththechipandthesystemlevel.Atthechiplevel,singlechipsarenowbeingproducedwhichareequivalenttoboardlevelsofonlythepreviousyearortwo.Thesechipshavemicroprocessor,memoryinRAMandROM,IOPortsbothserialandparallel,A/Dtimer,flagsandotherfunctionsonchip.Atthesystemlevel,thenewchipsmakenewarchitecturespossible.Theobjectiveofthispaperistoshowhowtechnologycaninfluencesystemarchitectureinthefieldoffirecontrol.Thenewhighdensitysinglechipmicrocontrollersareincorporatedinthedesignofalargescalesystemandyetweobtainasmallersystemwithabetterperformance.Intermsoffiredetectionandalarmmonitoring,thisisreflecteddirectlyinthelocalstationhardware,becauseoftheirremotenessandpowersupplyrequirements.AcompletelocalstationcanbedesignedaroundasingleCMOSchipwithpowerconsumptionofafewmWdependingonsystemoperation.Thisapproachreducesthecostandcomplexityofdesign,implementationandmaintenanceandprovideseasilyexpandableandportabledesign.Thisimplementationwasnotpossiblewitholdtechnology.Mostoffiredetection/monitoringsystemsavailablearetailoredtowardsaspecificapplicationandlacktheuseofrecentadvancesinCMOSVLSItechnology.Inthisstudy,wedevelopafiredetection/monitoringsystemwhichisgeneralinconcept,readilyimplementableinamultitudeofapplicationsforearlydetectionofafirebeforeitbecomescritical,forequipmentandevacuationofpersonnel.Here,weproposeacentralcontrolanddistributedcontrol/detection/monitoringwithadequatecommunication,whereuseismadeofsingle-chipmicrocontrollersinthelocalstations,thusimprovingcontrollabilityandobservabilityofthemonitoringprocess.2DetectionandalarmdevicesAbasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletorinfrareddetectorsorflameflicker,isbasedondetectingthebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyuseddetectordevices.WhenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreasesfromthepAtothemArange(say,fromamere15pAinthedormantmodeto60mA)intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousoperatingconditions,suchasthosegiveninTable1.Themoresensitivethedetector,themoresusceptibleitistofalsealarms.Inordertocontrolthedetectorprecisely,eitherofthefollowingmethodsisused:acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwhenflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.Alarmdevices,apartfromtheusualaudibleorvisiblealarms,mayincorporatesolidstatesoundreproductionandemergencyvoicecommunicationorprintersthatrecordtime,date,locationandotherinformationrequiredbythestandardcodeofpracticeforfireprotectionforcomplexplants.Heaviside4hasanexcellentreviewofalltypesofdetectorsandextinguishersystems.2.1ControlphilosophyanddivisionoflabourOurcontrolphilosophyisimplementedhierarchically.Threelevelsofsystemhierarchyareimplemented,withtwolevelsofdecisionmaking.Thereisnocommunicationbetweenequipmentonthesamelevel.Interactionbetweenlevelsoccursbyupwardstransferofinformationregardingthestatusofthesubsystemsanddownwardstransferofcommands.ThisisshowninFig.1whereatlevel1isthecentralstationmicrocomputerandistheultimatedecisionmaker(whennotinmanualmode).Atlevel2arethelocalcontrollers,whichresideinthelocalstations.Atlevel3aretheactualdetectorsandactuators.Amanualmodeofoperationisprovidedatalllevels.Informationregardingthestatusofalldetectorsistransmittedonaperareabasistothelocalcontrollers.Theirinformationiscondensedandtransmittedupwardtothecentralmicrocomputer.Transferofstatusisalwaysunidirectionalandupwards.Transferofcommandsisalwaysunidirectionalanddownwards,withexpansionatthelocalcontrollevel.Thisapproachpreservesthestrictrulesofthehierarchyforexactmonitoringdetectionandalarmsystemsassociatedwithhighriskplants.Theclassificationofthetwolayersofcontrolsisbaseduponlayersofdecisionmaking,withrespecttothefactsthat(a)Whenthedecisiontimecomes,themakingandimplementationofadecisioncannotbepostponed(b)Thedecisionshaveuncertainty(c)Itwillisolatelocaldecisions(e.g.locallywemighthaveanalarmalthoughtheremaybeafaultwiththesystem)3GeneralhardwareI:Fig.2depictsourdesigninthesimplestofforms.Thesystemusesanopenpartylineapproachwithfourconductorcablesgoinginaloopsharedbyalltheremotedevicesandthecontrolpanel.Thisapproachissimpleinconceptandiseconomicallyfeasible.However,onemajordisadvantageisthedependencyonasinglecableforpowerandsignaling.Incaseswherereliabilityisofextremeimportance,twooreventhreecablestakingdifferentroutesthroughoutthesystemmaybeconnectedinparallel.Fig.3givesthedrivercircuitryrequiredtoderiveanexpandablebus.Thisdesigntakesadvantageofrecentadvancesinthesinglechipmicrocomputertechnologytoreducetheinterfacebetweenthecentralstationandthelocalstations.3.1CentralcontroltaskAcentralunitprovidesacentralizedpointtomonitorandcontrolthesystemactivities.Inthesystemtobedescribedthecentralcontrolunitservesafivefoldpurpose.(i)Itreceivesinformationfromthelocalstationsandoperatesthealarmsandotheroutputdevices.(ii)Itnotifiestheoperatorincaseofsystemmalfunction.(iii)Itprovidesanoverallsystemcontrolmanualandautomatic.(iu)Itprovidesasystemtestpointoflocalstationsanditself.(u)Itprovidesacentralpointforobservation,learningandadaptation.3.2LocalstationsThelocalstationscantakelocaldecisionsregardingrecognitionofarisksituation,andactindependentlyonlocalaffairs.Inthistechniquewedependonload-typecoordination,e.g.thelowerlevelunitsrecognizetheexistenceofotherdecisionunitsonthesamelevel;thecentralorthetoplevelprovidesthelowerunitswithamodeloftherelationshipbetweenitsactionandtheresponseofthesystem.Itisevidentthatapowerfulmachineisrequiredatthisstagesothatalltherequiredfunctionscanbeimplemented.Theavailabilityofthenewgenerationofmicrochipsmakesthisarchitectureafeasiblesolution.Asinglechipmicrocomputerwaschosenoverdiscretedigitalandanaloguedevicestointerfacetothefielddevicesandtothecentralmicrocomputer.Thisisthemainreasonthatpreviouslythisapproachwasnotfeasible.Inselectingthemicrocomputerforthelocalstations,thecriterionwastherequirementforachipwhichcontainsthemostintegrationoftheanalogueanddigitalportsrequiredfortheinterfaceandtheutilizationofCMOStechnologyowingtoremotenessofthelocalstations.ThechoicewastheMotorola68HC11A4,forthefollowingreasons:(a)ItisCMOStechnology;thisreducespowerconsumption.(b)IthasaUARTonboard;thisfacilitatesserialcommunication.(e)Ithasana/dconverteronboard;thiseliminatesanexternalA/D.(d)Ithas4KofROM,256bytesofRAM,512bytesofEERROMwith401/0linesanda16bittimer;thissatisfiedallourmemoryand1/0requirementsatthelocalstationside.4SystemimplementationThelocalstation:Fig.3istheblockdiagramofthecircuitusedtoutilizetheMC68HCllA4asaremotefiredetectingcircuitwhileFig.4illustratesthesamecircuitinanexpandedform.Itcanbeseenthatthesinglemicrocontrollercanbeusedtomonitormorethanonedetector,thusreducingsystemcost.Thelooppowersupply,whichisusuallybetween28and26V,isfurtherregulatedbya5V100mAmonolithiclowpowervoltageregulatortosupplypowertothemicrocontroller.Theonboardoscillator,coupledwithanexternalcrystalof2.4576MHz,suppliesthemicrocontrollerwithitstimingsignalwhichisdividedinternallybyfourtoyieldaprocessorfrequencyof614.4kHz,whichisanevenmultipleoftheRS2327baudrategenerator.InthisSectionthetermsupervisedinputoroutputwillbeusedtomeanthatthefunctioninquestionismonitoredforopen-andshort-circuitconditionsinadditiontoitsothernormalfunctions.MoreinformationcanbefoundinReference9.5Mainloop6ConclusionThispaperdescribesthedevelopmentofalargescalefiredetectionandalarmsystemusingmulti-singlechipmicrocomputers.Thearchitectureusedisatwo-levelhierarchyofdecisionmaking.ThisarchitectureismadepossiblebythenewCMOSmicrocontrollerswhichrepresentahighpackingdensityatalowpowerconsumptionyetarepowerfulindataprocessingandthusindecisionmaking.Eachlocalstationcouldmakeanautonomousdecisionifthehigherlevelofhierarchyallowsittodoso.Ithasbeentriedtokeepthesystemdesigningeneralformatsoitcanbeadaptedtovaryingsituations.Aprototypeofthedescribedsystemhasbeenbuiltandtested10.ThecontrolpartofthecentralstationisimplementedwithadevelopmentcardbasedonMC68000microprocessor(MEX68KECB,byMotorola),whichhasabuilt-inmonitorcalledTutor.Theapplicationprogramsweredevelopedusingthefeaturesprovidedbythismonitor.ThelocalstationscontrollersweredesignedusingtheMC68705R3,single-chipmicrocontroller.7References1Fireprotectionguidelinesfornuclearp