机械外文翻译--应用于电气系统的可编程序控制器.doc

本科毕业论文（设计）外文资料翻译学生姓名：所在院系：机电学院所学专业：机电技术教育导师姓名：完成时间：Programmabledesignedforelectro-pneumaticsystemscontrollerAbstractThisprojectdealswiththestudyofelectro-pneumaticsystemsandTheprogrammablecontrollerthatprovidesaneffectiveandeasywaytoControlthesequenceofthepneumaticactuatorsmovementandthestatesofpneumaticsystem.Theprojectofaspecificcontrollerforpneumaticapplicationsjointhestudyofautomationdesignandthecontrolprocessingofpneumaticsystemswiththeelectronicdesignbasedonmicrocontrollerstoimplementtheresourcesofthecontroller.1.IntroductionTheautomationsystemsthatuseelectro-pneumatictechnologyareformedmainlybythreekindsofelements:actuatorsormotors,sensorsorbuttonsandcontrolelementslikevalves.Nowadays,mostofthecontrolelementsusedtoexecutethelogicofthesystemweresubstitutedbytheProgrammableLogicController(PLC).Sensorsandswitchesarepluggedasinputsandthedirectcntrolvalvesfortheactuatorsarepluggedasoutputs.Aninternalprogramexecutesallthelogicnecessarytothesequenceofthemovements,simulatesothercomponentslikecounter,timerandcontrolthestatusofthesystem.WiththeuseofthePLC,theprojectwinsagility,becauseitispossibletocreateandsimulatetheaystemasmanytimesasnended.therefore,timecanbesaved,riskofmistakesreducedandcomplexitycanbeincreasedusingthesameelements.AconventionalPLC,thisispossibletofindonthemarketfrommanycompanies,offersmanyresourcestocontrolnotonlypneumaticsystems,butallkindsofsystemthatuseselectricalcomonents.thePLCcanbeveryversatileandrobustbeappliedinmanykindsofapplicationintheindustryorevensecuritysystemandautomationofbuildings.Becauseofthosecharacteristics,insomeapplicationsthePLCofferstomuchresourcesthatarenotevenusedtocontrolthesystem,electro-pneumaticsystemisoneofthiskindofapplication.TheuseofPLC,especiallyforsmallSizesystems,canbeveryexpensivefortheautomationproject.Analterativeinthiscaseistocreateaspecificcontrollerthatcanoffertheexactlysizeandresourcesthattheprojectnends.thiscanbemadeusingmicrcontrollersasthebaseofthiscontroller.Thecontroller,basedonmicrocontroller,canbeveryspecificandadaptedtoonlyOnekindofmachineoritcanworkasagenericcontrollerthatcanbeprogrammed.AsausualPLCandworkwithlogicthatcanbechanged.Allthecharacteristicsdependonwhatisneededandhowmuchexperiencethedesignerhaswithdevelopinganelectroniccircuitandfirmwareformicrocontroller.Butthemainadvantageofdesignthecontrollerwiththemicrocontrolleristhatthedesignerhasthetotalknowledgeofhiscontroller,whichmakesitpossibletocontrolthesizeofthecontroller,changethecomplexityandtheapplicationofit.Itmeansthattheprojectgetsmoreindependencefromothercompanies,butatthesametimetheresponsibilityofthecontrolofthesystemstaysatthedesignerhands.2.Electro-pneumaticsystemOnautomationsystemonecanfindthreebasiccomponentsmentionedbefore,plusAlogiccircuitthatcontrolsthesystem.Anadequatetechniqueisneededtoprojectthelogiccircuitandintegrateallthenecessarycomponentstoexecutethesequenceofmovementsproperly.Forasimpledirectsequenceofmovementanintuitivemethodcanbeused1,5,butforindirectormorecomplexsequencestheintuitioncangenerateaverycomplicatedcircuitandsignalmistakes.Itisnecessarytouseanothermethodthatcansavetimeoftheproject,makeacleancircuit,caneliminateoccasionalsignaloverlappingandredundantcircuits.Thepresentedmethodiscalledstep-by-steporlgorithmic,itisvalidforpneumaticandelectro-pneumaticsystemsanditwasusedasabaseinthiswork.Themethodconsistsofdesigningthesystemsbasedonstandardcircuitsmadeforeachchangeonthestateoftheactuators,thesechangesarecalledsteps.Thefirstpartistodesignthosekindsofstandardcircuitsforeachstep,thenexttaskistolinkthestandardcircuitsandthelastpartistoconnectthecontrolelementsthatreceivesignalsfromsensors,switchesandthepreviousmovements,andgivetheairorelectricitytothesupplylinesofeachstep.InFigs.(1)and(2)thestandardcircuitsaredrawnforpneumaticandelectro-pneumaticsystem.Itispossibletoseetherelationswiththepreviousandthenextsteps.3.themethodappliedinsidethecontrollerTheresultofthemethodpresentedbeforeisasequenceofmovementsoftheactuatorthatiswelldefinedbystepas.Itmeansthateachchangeonthepositionoftheactuatorsisanewstateofthesystemandthetransitionbetweenstatesiscalldstep.Thestandardcircuitdescribedbeforehelpsthedesignertodefinethestatesofthesystemsandtodefinetheconditiontoeachchangebetweenthestates.Intheendofthedesign,thesystemisdefinedbyasequencethatneverchancesandstatesthathavetheinputsandtheoutputswelldefined.Theinputsaretheconditionforthetransitionandtheoutputsaretheresultofthetransition.Alltheconfigurationofthosestepsstaysinsideofthemicrocontrollerandisexecutedthesamewayitwasdesigned.Thesequenceofstringsareprogrammedinsidethecontrollerwith5bytes；eachstringhastheconfigurationofonestepoftheprocessTherearetwobytesfortheinputs,onebytefortheoutputsandtwomorefortheotherconfigurationsandauxiliaryfunctionsofthestep.Afterprogramming,thissequenceofstringsissavedinsideofanon-volatilMemoryofthemicrocontroller,sotheycanbereadandexecuted.ThecontrollertaskisnottoworkinthesamewayasaconventionalPLC,butthepurposeofitistobeanexampleofaversatilecontrollerthatisdesignforanspecificarea.AconventionalPLCprocessthecontrolofthesystemusingacyclewhereitmakesanimageoftheinputs,executealltheconditionsdefinedbytheconfigurationprogrammedinside,andthenupdatethestateoftheoutputs.Thiscontrollerworksinadifferentway,whereitreadtheconfigurationofthestep,waittheconditionofinputstobesatisfied,thenupdatethestateortheoutputsandafterthatjumptothenextstepandstarttheprocessagain.Itcangeneratesomelimitations,asthefactthatthiscontrollerca