基于单片机的火灾探测和监控系统大学毕业论文外文文献翻译及原文Word格式文档下载.docx

基于单片机的火灾探测和监控系统大学毕业论文外文文献翻译及原文Word格式文档下载.docx

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外文文献原稿和译文

原　　稿

Multiplesingle-chipmicrocomputerapproachto

firedetectionandmonitoringsystem

A.J.AI-Khalili,MSc,PhD

D.AI-Khalili,MSc,PhD

M.S.Khassem,MSc

Indexingterm:

Hazards,Design,Plantconditionmonitoring

Abstract:

Acompletesystemforfiredetectionandalarmmonitoringhasbeenproposedforcomplexplants.Thesystemusesmultiplesinglechiparchitectureattachedtoapartyline.Thecontrolalgorithmisbasedonatwo-levelhierarchyofdecisionmaking,thusthecomplexityisdistributed.Acompletecircuitdiagramisgivenforthelocalandthecentralstationwithrequirementsforthesoftwarestructure.Thedesigniskeptingeneralformsuchthatitcanbeadaptedtoamultitudeofplantconfigurations.Itisparticularlyshownhownewdevelopmentsintechnology,especiallyCMOSsinglechipdevices,areincorporatedinthesystemdesigntoreducethecomplexityoftheoverallhardware,e.g.bydecomposingthesystemsuchthatlowerlevelsofhierarchyareabletohavesomeautonomyindecisionmaking,andthusamorecomplexdecisionissolvedinasimpledistributedmethod.

1Detectionandalarmdevices

Abasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletorinfrareddetectorsorflameflicker,isbasedondetecting

thebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyused

detectordevices.Whenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreases

fromthepAtothemArange（say,fromamere15pAinthedormantmodeto60mA）intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousoperatingconditions,suchasthose

giveninTable1.Themoresensitivethedetector,the

moresusceptibleitistofalsealarms.Inordertocontrolthedetectorprecisely,eitherofthefollowingmethodsisused:

acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;

smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwhenflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.

Alarmdevices,apartfromtheusualaudibleorvisiblealarms,mayincorporatesolidstatesoundreproductionandemergencyvoicecommunicationorprintersthatrecordtime,date,locationandotherinformationrequiredbythestandardcodeofpracticeforfireprotectionforcomplexplants.Heaviside[4]hasanexcellent

reviewofalltypesofdetectorsandextinguishersystems.

1.1Controlphilosophyanddivisionoflabour

Ourcontrolphilosophyisimplementedhierarchically.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）

2Generalhardware

I:

Fig.2depictsourdesigninthesimplestofforms.Thesystemusesanopenpartylineapproachwithfourconductorcablesgoinginaloopsharedbyalltheremotedevicesandthecontrolpanel.Thisapproachissimpleinconceptandiseconomicallyfeasible.However,onemajordisadvantageisthedependencyonasinglecableforpowerandsignaling.Incaseswherereliabilityisofextremeimportance,twooreventhreecablestakingdifferent

routesthroughoutthesystemmaybeconnectedinparallel.Fig.3givesthedrivercircuitryrequiredtoderiveanexpandablebus.Thisdesigntakesadvantageofrecentadvancesinthesinglechipmicrocomputertechnologytoreducetheinterface

betweenthecentralstationandthelocalstations.

2.1Centralcontroltask

Acentralunitprovidesacentralizedpointtomonitorandcontrolthesystemactivities.Inthesystemtobedescribedthecentralcontrolunitservesafivefoldpurpose.

（i）Itreceivesinformationfromthelocalstationsandoperatesthealarmsandotheroutputdevices.

（ii）Itnotifiestheoperatorincaseofsystemmalfunction.

（iii）Itprovidesanoverallsystemcontrolmanualandautomatic.

（iu）Itprovidesasystemtestpointoflocalstationsanditself.

（u）Itprovidesacentralpointforobservation,learningandadaptation.

2.2Localstations

Thelocalstationscantakelocaldecisionsregardingrecognitionofarisksituation,andactindependentlyonlocalaffairs.Inthistechniquewedependon‘load-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.

3Systemimplementation

Thelocalstation:

Fig.3istheblockdiagramofthecircuitusedtoutilizetheMC68HCllA4asaremotefiredetectingcircuitwhileFig.4illustratesthesamecircuitinanexpandedform.Itcanbeseenthatthesinglemicrocontrollercanbeusedtomonitormorethanonedetector,thusreducingsystemcost.

Thelooppowersupply,whichisusuallybetween28and26V,isfurtherregulatedbya5V100mAmonolithiclowpowervoltageregulatortosupplypowertothemicrocontroller.Theonboardoscillator,coupledwithanexternalcrystalof2.4576MHz,suppliesthemicrocontrollerwithitstimingsignalwhichisdividedinternallybyfourtoyieldaprocessorfrequencyof614.4kHz,whichisanevenmultipleoftheRS232[7]baudrategenerator.InthisSectiontheterm‘supervisedinputoroutput’willbeusedtomeanthatthefunctioninquestionismonitoredforopen-andshort-circuitconditionsinadditiontoitsothernormalfunctions.MoreinformationcanbefoundinReference9.

4Mainloop

5Conclusion

Thispaperdescribesthedevelopmentofalargescalefiredetectionandalarmsystemusingmulti-singlechipmicrocomputers.Thearchitectureusedisatwo-levelhierarchyofdecisionmaking.ThisarchitectureismadepossiblebythenewCMOSmicrocontrollerswhichrepresentahighpackingdensityatalowpowerconsumptionyetarepowerfulindataprocessingandthusindecisionmaking.Eachlocalstationcouldmakeanautonomousdecisionifthehigherlevelofhierarchyallowsittodoso.Ithasbeentriedtokeepthesystemdesigningeneralformatsoitcanbeadaptedtovaryingsituations.Aprototypeofthedescribedsystemhasbeenbuiltandtested[10].ThecontrolpartofthecentralstationisimplementedwithadevelopmentcardbasedonMC68000microprocessor（MEX68KECB,byMotorola）,whichhasabuilt-inmonitorcalledTutor.Theapplicationprogramsweredevelopedusingthefeaturesprovidedbythismonitor.Thelocalstations’controllersweredesignedusingtheMC68705R3,single-chipmicrocontroller.

7References

1‘Fireprotectionguidelinesfornuclearpowerplants’,USNRCRegulatoryGuide1.120

2BAGCHI,C.N.:

‘Amulti-leveldistributedmicroprocessorsystemforanuclearpowerplantfireprotec