1、PLCControloftheApplication1MotivationProgrammableLogicControllers(PLC)/acomputingdeviceinventedbyRichardE/Morleyin1968/havebeenwidelyusedinindustryincludingmanufacturingsystems/transportationsystems/chemicalprocessfacilities/andmanyothers/Atthattime/thePLCreplacedthehardwiredlogicwithsoft-wiredlogic
2、orso-calledrelayladderlogic(RLL)/aprogramminglanguagevisuallyresemblingthehardwiredlogic/andreducedtherebytheconfigurationtimefrom6monthsdownto6days/AlthoughPCbasedcontrolhasstartedtocomeintoplace/PLCbasedcontrolwillremainthetechniquetowhichthemajorityofindustrialapplicationswilladhereduetoitshigher
3、performance/lowerprice/andsuperiorreliabilityinharshenvironments/Moreover/accordingtoastudyonthePLCmarketofFrostandSullivan1995/anincreaseoftheannualsalesvolumeto15millionPLCsperyearwiththehardwarevalueofmorethan8billionUSdollarshasbeenpredicted/thoughthepricesofcomputinghardwareissteadilydropping/T
4、heinventorofthePLC/RichardEMorley/fairlyconsidersthePLCmarketasa5-billionindustryatthepresenttime/Particularly/practicalproblemsinPLCprogrammingaretoeliminatesoftwarebugsandtoreducethemaintenancecostsofoldladderlogicprograms/ThoughthehardwarecostsofPLCsaredroppingcontinuously/reducingthescantimeofth
5、eladderlogicisstillanissueinindustrysothatlow-costPLCscanbeused/Ingeneral/theproductivityingeneratingPLCisfarbehindcomparedtootherdomains/forinstance/VLSIdesign/whereefficientcomputeraideddesigntoolsareinpractice/ExistentsoftwareengineeringmethodologiesarenotnecessarilyapplicabletothePLCbasedsoftwar
6、edesignbecausePLC-programmingrequiresasimultaneousconsiderationofhardwareandsoftware/Thesoftwaredesignbecomes/thereby/moreandmorethemajorcostdriver/Inmanyindustrialdesignprojects/morethanSO0/aofthemanpowerallocatedforthecontrolsystemdesignandinstallationisscheduledfortestinganddebuggingPLCprogramsRo
7、ckwell/1999/Inaddition/currentPLCbasedcontrolsystemsarenotproperlydesignedtosupportthegrowingdemandforflexibilityandreconfigureabilityofmanufacturingsystems/Afurtherproblem/impellingtheneedforasystematicdesignmethodology/istheincreasingsoftwarecomplexityinlarge-scaleprojects/1ObjectiveandSignificanc
8、eoftheThesisTheobjectiveofthisthesisistodevelopasystematicsoftwaredesignmethodologyforPLCoperatedautomationsystems/Thedesignmethodologyinvolveshigh-leveldescriptionbasedonstatetransitionmodelsthattreatautomationcontrolsystemsasdiscreteeventsystems/astepwisedesignprocess/andsetofdesignrulesprovidingg
9、uidanceandmeasurementstoachieveasuccessfuldesign/Thetangibleoutcomeofthisresearchistofindawaytoreducetheuncertaintyinmanagingthecontrolsoftwaredevelopmentprocess/thatis/reducingprogramminganddebuggingtimeandtheirvariation/increasingflexibilityoftheautomationsystems/andenablingsoftwarereusabilitythro
10、ughmodularity/Thegoalistoovercomeshortcomingsofcurrentprogrammingstrategiesthatarebasedontheexperienceoftheindividualsoftwaredeveloper/AsystematicapproachtodesigningPLCsoftwarecanovercomedeficienciesinthetraditionalwayofprogrammingmanufacturingcontrolsystems/andcanhavewideramificationsinseveralindus
11、trialapplications/Automationcontrolsystemsaremodeledbyformallanguagesor/equivalently/bystatemachines/Formalrepresentationsprovideahigh-leveldescriptionofthebehaviorofthesystemtobecontrolled/Statemachinescanbeanalyticallyevaluatedastowhetherornottheymeetthedesiredgoals/Secondly/astatemachinedescripti
12、onprovidesastructuredrepresentationtoconveythelogicalrequirementsandconstraintssuchasdetailedsafetyrules/Thirdly/well-definedcontrolsystemsdesignoutcomesareconducivetoautomaticcodegeneration-Anabilitytoproducecontrolsoftwareexecutableoncommercialdistinctlogiccontrollerscanreduceprogramminglead-timea
13、ndlaborcost/Inparticular/thethesisisrelevantwithrespecttothefollowingaspects/(1)Customer-DrivenManufacturingInmodernmanufacturing/systemsarecharacterizedbyproductandprocessinnovation/becomecustomer-drivenandthushavetorespondquicklytochangingsystemrequirements/Amajorchallengeisthereforetoprovideenabl
14、ingtechnologiesthatcaneconomicallyreconfigureautomationcontrolsystemsinresponsetochangingneedsandnewopportunities/Designandoperationalknowledgecanbereusedinreal-time/therefore/givingasignificantcompetitiveedgeinindustrialpractice/(2)HigherDegreeofDesignAutomationandSoftwareQualityStudieshaveshowntha
15、tprogrammingmethodologiesinautomationsystemshavenotbeenabletomatchrapidincreaseinuseofcomputingresources/Forinstance/theprogrammingofPLCsstillreliesonaconventionalprogrammingstylewithladderlogicdiagrams/Asaresult/thedelaysandresourcesinprogrammingareamajorstumblingstonefortheprogressofmanufacturingi
16、ndustry/Testinganddebuggingmayconsumeover50%ofthemanpowerallocatedforthePLCprogramdesign/StandardsIEC60848/1999；IEC-61131-3/1993；IEC61499/1998；ISO15745-1/1999havebeenformedtofixanddisseminatestate-of-the-artdesignmethods/buttheynormallycannotparticipateinadvancingtheknowledgeofefficientprogramandsys
17、temdesign/Asystematicapproachwillincreasethelevelofdesignautomationthroughreusingexistingsoftwarecomponents/andwillprovidemethodstomakelarge-scalesystemdesignmanageable/Likewise/itwillimprovesoftwarequalityandreliabilityandwillberelevanttosystemshighsecuritystandards/especiallythosehavinghazardousim
18、pactontheenvironmentsuchasairportcontrol/andpublicrailroads/(3)SystemComplexityThesoftwareindustryisregardedasaperformancedestructorandcomplexitygenerator/Steadilyshrinkinghardwarepricesspoilstheneedforsoftwareperformanceintermsofcodeoptimizationandefficiency/Theresultisthatmassiveandlessefficientso
19、ftwarecodeononehandoutpacesthegainsinhardwareperformanceontheotherhand/Secondly/softwareproliferatesintocomplexityofunmanageabledimensions；softwareredesignandmaintenance-essentialinmodernautomationsystems-becomesnearlyimpossible/Particularly/PLCprogramshaveevolvedfromacouplelinesofcode25yearsagototh
20、ousandsoflinesofcodewithasimilarnumberofI/Opoints/Increasedsafety/forinstancenewpoliciesonfireprotection/andtheflexibilityofmodernautomationsystemsaddcomplexitytotheprogramdesignprocess/Consequently/thelife-cyclecostofsoftwareisapermanentlygrowingfractionofthetotalcost/80-90%ofthesecostsaregoinginto
21、softwaremaintenance/debugging/adaptationandexpansiontomeetchangingneeds/(4)DesignTheoryDevelopmentToday/theprimaryfocusofmostdesignresearchisbasedonmechanicalorelectricalproducts/Oneoftheby-productsofthisproposedresearchistoenhanceourfundamentalunderstandingofdesigntheoryandmethodologybyextendingitt
22、othefieldofengineeringsystemsdesign/Asystemdesigntheoryforlarge-scaleandcomplexsystemisnotyetfullydeveloped/Particularly/thequestionofhowtosimplifyacomplicatedorcomplexdesigntaskhasnotbeentackledinascientificway/Furthermore/buildingabridgebetweendesigntheoryandthelatestepistemologicaloutcomesofforma
23、lrepresentationsincomputersciencesandoperationsresearch/suchasdiscreteeventsystemmodeling/canadvancefuturedevelopmentinengineeringdesign/(5)ApplicationinLogicalHardwareDesignFromalogicalperspective/PLCsoftwaredesignissimilartothehardwaredesignofintegratedcircuits/ModernVLSIdesignsareextremelycomplex
24、withseveralmillionpartsandaproductdevelopmenttimeof3yearsWhitney/1996/Thedesignprocessisnormallyseparatedintoacomponentdesignandasystemdesignstage/Atcomponentdesignstage/singlefunctionsaredesignedandverified/Atsystemdesignstage/componentsareaggregatedandthewholesystembehaviorandfunctionalityistestedthroughsimulation/Ingeneral/acompleteverificationisimpossible/Hence/asystematicapproachasexemplifiedforthePLCprogramdesignmayimpactthelogicalhardwaredesign/
免责声明：
1. 《外文翻译--关于PLC的控制应用》内容来源于互联网，版权归原著者或相关公司所有。
2. 若《86561825文库网》收录的文本内容侵犯了您的权益或隐私，请立即通知我们删除。