基于单片机的温度控制外文文献及中文翻译.docx

基于单片机的温度控制外文文献及中文翻译.docx

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基于单片机的温度控制外文文献及中文翻译

ＴemｐｅratｕreContｒol　Usinga　Ｍｉcrocoｎtroller:

ＡnＩnterｄiscｉｐｌinａryUndｅrｇraduaｔeEｎgineｅringDeｓiｇnＰｒｏject

JamesS.　ＭcDｏnald

DeｐartmentoｆEngｉnｅeringＳciｅｎce

ＴrinitｙUniｖeｒsity

SanＡnｔoniｏ，ＴＸ782１2

Abｓｔｒact：

Tｈispapeｒdescrｉｂesanｉnｔeｒdiｓｃiｐlinary　dｅsignｐｒoject　whｉchｗasｄoｎeundertｈｅauthor’s　supeｒvisioｎbyagｒoupoffoｕr　seniｏrstudenｔs　ｉｎｔheDepartｍentｏｆEngｉneerｉｎｇScienceatTrｉnｉtyUniversｉty．Theoｂｊectiveｏftｈe　proｊecｔwastodeveｌopateｍｐｅratuｒe　controlｓystemｆoranａiｒ-fillｅｄcｈamｂeｒ.Thesystem　wａs　toalｌowｅnｔrｙof　aｄｅsirｅd　cｈａmbｅrｔemperatuｒe　inaprescribｅdｒａnge　aｎdtoexhｉｂｉtoveｒsｈootand　ｓteady-ｓtａte　ｔeｍｐeｒatureeｒrorofless　ｔhan　１dｅgrｅe　Keｌviniｎtｈeａctual　chamｂeｒ　temｐerature　stepresponｓe.　Ｔｈｅdｅｔailsｏftｈedeｓiｇndevelopedby　thｉsgrｏｕｐ　of　studｅnts,baseｄonaMｏｔorｏlaMＣ68HC05ｆａｍilｙmicｒocｏntroller，aredｅｓｃribｅd.Theｐｅｄagogicalvａｌueof　thｅｐroblemisalsodiscussedtｈrougｈadescriｐtionofsomeof　thekeyｓteｐｓｉntheｄesign　ｐrocｅｓs.　Itiｓshｏwnthａt　tｈesolutioｎrequiresbroadknoｗｌeｄgｅdrawnｆrｏmｓｅveralengiｎeｅringdiｓciplｉnesincluｄinｇｅlectriｃaｌ,mｅchａnｉcaｌ，andｃontｒｏlsystems　engineering．

1Introduction

Ｔｈedesiｇnｐrｏjectｗhichiｓtｈesuｂjｅcｔofthｉsｐａpｅroｒiｇinaｔeｄfromａｒeal-woｒldapｐlicatｉon.Aｐrotoｔyｐｅoｆａmicrｏsｃopeｓlideｄｒyerhａdbｅendｅveｌopedaroｕnd　ａｎ　OmｅｇaＴＭｍoｄelＣＮ-3９0tｅmｐerａｔurecontrolｌer,andtheoｂjeｃｔｉvｅｗasｔｏdeveloｐa　cuｓtoｍ　ｔemｐerａture　coｎtrolsystemｔｏｒepｌａceｔheOｍｅgasystem．Theｍoｔiｖatiｏｎ　wａsｔｈata　cuｓｔomcontｒoｌleｒtaｒｇeted　spｅciｆｉcallyｆoｒｔｈe　aｐpｌiｃａtiｏn　shouldbｅable　ｔｏachｉevethｅ　saｍefunctionａlity　aｔa　ｍuch　loｗeｒ　cost，　astheOmeｇａsystemｉsuｎｎｅｃessarilyversatｉlｅanｄeｑｕｉppedｔohanｄlｅawidevariｅty　ofapｐｌications．

Ｔhｅｍechａnicallaｙouｔofthｅsliｄedryerｐrｏｔotｙpeｉs　shoｗniｎFigurｅ1.　Ｔhｅmaineｌeｍｅntoｆthedryeris　alａrｇe,　iｎｓulａｔed,air-fｉllｅdｃhambeｒｉnwhich　mｉｃroscopesliｄes，eａｃｈｗｉtha　tｉssuesａmpｌe　ｅnｃａsediｎ　ｐａraｆfｉｎ,caｎbｅｓetoｎcaddieｓ.In　orｄerｔhat　theparaffiｎmａinｔaintheproｐer　ｃonsisｔenｃｙ，thetｅmperaturein　theslｉde　chａmｂermustｂemaiｎtａｉnｅdａt　ａ　desirｅd（constant）temperatｕre．A　seｃoｎdｃhamｂｅr（tｈeｅleｃtrｏniｃsencｌｏsure）ｈousesareｓisｔiｖeｈeateｒ　ａnd　theｔemperａtｕｒｅcontrｏlleｒ,aｎd　a　fａn　ｍｏuntｅdｏn　ｔheｅｎｄｏfthedryｅrbloｗｓaiｒacrossｔheheater,carryｉngｈeatｉnｔothｅslｉdｅ　chaｍbeｒ．　Thiｓdesignｐrｏjecｔ　wasｃaｒｒieｄｏｕtdurｉngacａｄemｉcyｅａr19９６–9７byｆoｕrｓｔuｄentｓunderｔｈeauｔhor’ｓｓupervision　asa　SeｎiorDeｓiｇｎprojecｔ　in　ｔheDepａrtmentｏf　EnｇineｅringScienceatTｒinｉtyUnｉｖersitｙ.Theｐurposeｏfthispａpｅｒis

todescribｅ　theproblemanｄｔhestudents’　solutioｎiｎ　soｍedetail，anｄtodiｓcuss　someｏｆtｈepedagoｇｉｃａlopｐortunｉtｉesoffｅｒｅd　byaｎ　inｔｅrｄisciplｉnａｒｙdeｓignprｏjeｃtof　thｉs　tｙpｅ.Thｅstｕdeｎｔs’　oｗｎｒeｐorｔwasprｅsｅnteｄaｔ　ｔhe199７　ＮａtiｏnａlＣonferｅｎcｅonUnｄerｇｒaduatｅReseaｒch[１].　Sectioｎ2　ｇiveｓamoredetaiｌedstａtemenｔof　ｔｈe　problem,incｌudingperfｏrｍance　sｐeciｆiｃations,aｎdSｅctioｎ　３descrｉbesthestudentｓ’deｓign.Ｓecｔion4makesupthebuｌkofthepａｐer，andｄiscuｓsesｉｎsome　ｄetａiｌｓｅveｒaｌ　aspeｃｔsoｆ　thedｅsigｎpｒocｅssｗｈｉchofferｕｎiquｅpｅdaｇogical　opｐorｔｕｎities.Fiｎaｌly，Section５ｏffｅrssoｍeconclusions.

２Proｂlｅm　Statemeｎt

Tｈebａsｉc　ideaofthepｒojectisｔoｒeｐｌace　therelｅvantparｔsofthefｕncｔioｎａlｉty　of　ａnOｍegaCN-39０temｐeratuｒe　controｌleruｓｉngａcuｓtｏm－designｅdsｙstem.Ｔhe　ａpｐｌｉｃaｔiondicｔａtｅs　thatｔeｍperatureｓettingsareｕｓuaｌlｙ　keptconstaｎtfｏrlong　ｐeｒioｄsｏftime,buｔ　iｔ’s　nonethelesｓ　imporｔａｎｔtｈatstepchanｇｅｓbeｔrackeｄina“reasonａble”ｍanner.Thｕsｔhemaiｎｒequｉrｅmentｓboil　doｗntｏ

·ａlloｗiｎｇa　ｃｈamｂertｅmperatｕrｅseｔ－pointｔo　be　ｅnｔeｒeｄ,

·displayingboｔhｓet－pointａndactuａltemperａｔureｓ,and

·trackｉngstｅｐchaｎgｅsｉn　ｓeｔ-pｏiｎｔtempｅraｔure　ｗｉthacceｐｔaｂlerisｅ　ｔiｍe，ｓtｅaｄｙ-stａteerror,andｏvershｏｏt.

Ａltｈough　ｎoｔexpliｃiｔlyaｐart　of　thｅspeciｆicaｔionsinTable１，iｔwascｌeaｒthatthecustomeｒｄｅsiｒｅｄdigiｔal　disｐlaｙｓofset-ｐointanｄａctual　tｅmpeｒａtｕreｓ,andthat　sｅt-ｐｏinｔ　teｍperatuｒeenｔryshould　beｄigital　aswell（asｏpposｅdtｏ,　ｓａy,thｒoｕgｈ　aｐotentioｍeterｓeｔtｉnｇ）.

3Sysｔｅｍ　Ｄesｉgｎ

Theｒequirｅmentsfoｒdigitalｔｅmperaturｅｄisｐｌａyｓandsetpｏinteｎｔｒｙaloｎeaｒeenoｕghtodictａｔe　thaｔ　ａmicｒｏcontroｌleｒbased　dｅsｉgnｉs　likｅlythｅmｏst　aｐpropｒiatｅ.　Ｆigｕｒe　2shows　ａｂlock　diagrａmoｆthestudentｓ’ｄesign.

Tｈemicrocoｎｔrolｌeｒ，aMoｔoｒolaMC68HC７05B1６（680５for　short）,isｔhe　heart　oｆtｈesysteｍ.Itaｃceｐtｓ　inｐｕｔsｆromａ　ｓｉｍplefoｕr-key　keypａdｗhicｈallｏwｓpｅcｉficatioｎ　ｏf　theｓeｔ-ｐoiｎｔtｅｍperature,ａnditdisｐlaysｂｏthset-pｏiｎｔand　mｅasｕｒedchamｂeｒteｍｐerａturesusiｎｇtwo-diｇit　ｓeveｎ-ｓeｇｍeｎtLＥD　ｄisｐｌayｓ　contrｏｌlｅｄbyadispｌaｙdriveｒ.Aｌlthｅseinpｕtsandoutｐutsaｒe　accomｍodaｔeｄｂypaｒａlｌelpｏｒts　onｔhe680５.Cｈaｍber　temperaｔｕreis　sensｅdusinｇaｐrｅ-ｃaliｂratedtｈｅrｍistｏrａndinｐuｔviaｏnｅ　ofthe６80５’sａnａlog-to-diｇitａlinｐuts.Finally,apulsｅ-ｗidth　moduｌaｔion（PWM）outpｕｔｏnthe680５isｕseｄ　toｄrｉveａreｌaywhｉchswｉtｃｈes　linepower　totｈｅresｉsｔivｅ　heaｔerofｆaｎdon．

Fiｇｕre3shｏｗsamoredetａiｌedsｃhemａｔicoftｈeｅlectroｎｉｃsandｔheｉrｉntｅrfacing　tｏ　ｔhｅ　6８05．Tｈｅkｅｙpad，aSｔoｒm3K04110３,ｈas　fｏurkeys　wｈiｃhareintｅｒfａcedto　piｎsPA0｛　PA3of　Port　A，ｃonfiguｒedasinｐｕｔs.　Oneｋeyfunctｉonsaｓ　amodesｗitｃh.　Twoｍｏｄesaｒe　suｐpｏrted：

ｓetmodｅ　andrun　ｍｏde.Inｓetmoｄe　twoｏf　theｏtｈerkｅｙs　ａreusedtospecifｙthe　ｓet－pｏinｔ　temｐｅrａtuｒｅ:

　oneiｎcｒemeｎtｓitandｏne　decreｍeｎts．　Ｔhｅfoｕrtｈkeｙis　uｎuseｄ　aｔｐｒesent.TheLEDdiｓpｌayｓａｒe　drivｅnbyaHaｒｒisＳemｉｃoｎｄuctｏｒＩＣM7212ｄisplａy　ｄriver　ｉnteｒｆacedtｏｐinsPB０{PB6ｏfPortＢ，　ｃonｆｉgureｄasoutpuｔｓ.Thｅtempeｒａtｕrｅ-senｓiｎｇｔhｅrmiｓｔordｒives，ｔｈｒｏughａvolｔagedivｉdｅｒ,pinAN0（oneofｅiｇht　analoginputs）.　Ｆｉnalｌｙ,pinPＬMA（onｅ　oｆｔwo　ＰWMoutputs）　driｖestheheateｒrelay.

Softwａrｅoｎthｅ6805ｉmplemｅntｓtｈetemperａｔurecoｎtrol　aｌgｏｒｉtｈm,maintainstｈetｅｍｐeｒaｔuｒe　displays，aｎｄaltｅrsｔheｓet-poｉnｔinrespoｎse　ｔｏ　ｋeypadinputｓ.Because　it　is　notcoｍpｌeteatｔｈis　wｒiting,ｓｏftwareｗillｎoｔ　ｂediｓcｕssedindetaiｌ　inｔhｉspａｐer.Ｔhecontrolalgorithmiｎpaｒticularｈａs　ｎｏtｂeｅn　detｅｒmiｎed，butitis　ｌｉkelｙtobｅaｓimpｌe　proportionalｃontｒｏllerand　ｃｅｒｔainlyｎｏｔｍｏrｅ　ｃomplex　thanaＰID.Someｃoｎtroldesignissｕes　ｗilｌbｅｄiscussedinSectｉoｎ　4,however.

4TheDｅｓignProcｅｓs

Althoughｅssentiallyｔheproｊectisjusｔｔｏbｕilda　therｍｏstaｔ，iｔpｒｅsentsmany　nicepedagｏgｉｃaloppｏrｔｕniｔｉｅs.　Ｔhｅkｎｏｗledｇeａnｄeｘpeｒienｃｅbａｓｅ　ofaseｎｉｏrenｇineeringunｄergｒａｄuatearｅ　juｓtｅnouｇｈto　briｎg　himｏrhｅr　toｔhｅ　bｒinkｏfasｏｌutiｏntｏｖariousasｐeｃtsofｔｈｅ　proｂlｅm.Ｙet,　in　ｅａchcase，realwｏrｌdｃonｓiderationｓcoｍplｉcatethｅ　sitｕatｉonsignifiｃantlｙ.

Forｔｕnatelythｅsecomplicaｔionsaｒｅnotinｓurmountａblｅ,andｔｈeresultｉｓa　verybenefiｃialdｅsigｎexperience．Tｈｅ　remａiｎder　ｏf　thiｓsｅctｉon　looｋｓ　ata　fewａsｐecｔｓoｆ　ｔhｅｐrobｌemｗhiｃhpreｓentｔhetype　ofleaｒnｉng　ｏpportuniｔyjuｓt　deｓcribed.Sectioｎ　4.1discussesｓomeofthｅfｅatuｒｅsofa　ｓimｐｌified　matheｍatiｃalｍoｄeloｆthｅ　ｔheｒmaｌpropeｒties　of　tｈesystｅｍandｈowiｔcan　beｅasilｙvalidateｄexｐerimentally.Section　4.２dｅsｃrｉbeshowrealisｔｉccontｒｏｌａlgｏｒithm　deｓｉgnsｃanbearrivedａtuｓiｎgiｎtｒｏducｔｏryconｃeｐtsinｃoｎtｒｏｌdesign.Sectioｎ　4.3pointｓ　ouｔsｏmｅimｐoｒｔant　deficｉenciｅsofsucha　ｓiｍplifieｄmodeｌing/controldesiｇnｐrocess　andhowtheycａn　beoveｒcomｅtｈrougｈsiｍｕlatioｎ.Ｆinaｌly,Sｅctiｏｎ4.４givesａnovｅrviewofｓoｍｅof　tｈe　micrｏcontroｌleｒ-rｅlateｄｄesigｎｉsｓueｓ　whicｈariseanｄlｅarｎinｇopｐortｕnities　offered.

4.１MathemaｔicalＭodel

Ｌumｐｅd-elemｅntｔｈeｒmal　sｙstems　aredｅsｃribｅdｉnalｍost　anyintroductory　liｎｅａrcoｎｔrol　sｙｓtemstｅxt，anｄ　justthissoｒt　ｏfmoｄｅlｉsapplｉcａbｌｅtｏ　theslide　dryerproｂlem.　Figｕrｅ4sｈｏws　ａsｅcｏnd-oｒderlumｐeｄ-elemenｔｔhｅrmalｍodｅｌoｆtｈeｓlidedryer.Ｔｈe　state　ｖaｒiabｌesarｅthe　temperaturesTａｏf　ｔhe　ａir　inthｅ　bｏｘ　andTbofthe　boxitseｌf.Theinputｓtothｅ　system　aretheｐｏwerｏuｔｐutq（t）oftｈｅheateraｎdｔhｅ　ambienｔtemｐeratureT¥．　mａａndmbarｅtheｍaｓｓes　ofthｅ　airaｎd　theboｘ,ｒespecｔｉvely,aｎd　ＣaandＣbｔhｅｉrｓpecｉfｉｃhｅatｓ.μ１　ａｎｄμ2aｒｅｈｅatｔransfer　coｅｆficｉentｓfromtｈeaｉrtoｔｈe　bｏxａｎdfrom　theboxtotｈｅexterｎal　woｒlｄ,resｐeｃtｉvｅly.

Iｔ’ｓnｏthardtosｈoｗｔｈatｔhｅ（lｉｎeａｒizｅd）ｓｔatｅeｑuａtionscoｒrespondiｎg　toFigｕre4ａre

TakingLａplaｃetraｎsfoｒmｓof

（1）aｎd

（2）ａｎdｓolvinｇfoｒ　Ta（s）,　ｗhiｃｈ　isthｅ　ｏutｐutofｉｎｔereｓt,gives　tｈefoｌlowingopen－looｐ　model　oｆthｅtheｒmａl　ｓyｓｔｅｍ：

ｗhereＫisacoｎstantaｎdD（s）　ｉsasecond-oｒderｐolynomiａl．K,tz,and　theｃｏｅfficｉeｎtｓoｆＤ（s）areｆuｎctioｎsｏfｔhevａrｉoｕsｐaraｍeters　ａｐpｅarｉngiｎ

（1）　anｄ

（2）.Ofcoursethe　ｖaｒiousparameteｒsiｎ

（1）anｄ（２）are　compleｔｅlyunknowｎ，but　it’sｎot　hardｔosｈow　thａt,ｒｅgaｒdleｓｓofｔheｉrvａlues,Ｄ（ｓ）ｈastｗoｒealzeros.Therefoｒｅthｅmaintｒａｎｓfeｒfunｃtionoｆiｎterest（whicｈiｓｔheone　fｒom　Ｑ（s）,ｓincewｅ’ｌlaｓｓume　constant　aｍbientteｍperaｔuｒe）　ｃanｂｅ　ｗritten

Moreoveｒ,　ｉt’ｓnｏｔtｏoｈardtoshowｔhaｔ1=tp1　<１=tz　<１=tp2,ｉ.ｅ.，ｔhat　thｅzerolieｓbetｗeｅntheｔwｏpoｌes.Ｂoｔｈoftheseareexcelleｎｔｅxeｒcｉｓesfor　tｈｅ　ｓtudent,　ａnd　the　reｓulｔｉsｔｈeoｐenlooppole-ｚｅro　diaｇrａmofFigure　５.

Ｏｂtaｉniｎg　acｏｍpｌetetheｒmalmｏdel,tｈen,isreduced　tｏiｄentifyinｇtｈecｏnｓtａnt　Kandthethreeunknｏwｎｔｉmeconｓtantsin（3）.　Fｏuｒuｎknowｎpaｒaｍetｅrｓiｓquｉｔｅafew,butsｉmpｌｅexpeｒimeｎtｓ　shoｗ　tｈat１=tp1_１=tz；1=tｐ２　ｓo　tｈａttz；tp２_　0aｒｅgｏｏｄ　aｐｐrｏxｉmations.Thuｓtｈｅopen-loopｓysｔemisessenｔｉally　first-oｒｄer　andｃantheｒeforｅｂewritteｎ

　（whｅre　tｈesubsｃｒipｔp１ｈas　ｂeeｎｄｒopped）.

Ｓiｍpleopｅn－loｏpstep　ｒespｏnｓeeｘｐerimｅｎtsshowthａt，fｏrawiｄeranｇｅ　ｏfiniｔｉaｌｔeｍperaｔurｅsandheａtｉnｐｕｔs,K＿0：

１４　_＝W　andt＿295s.1

4.２Conｔroｌ　SysteｍDｅsｉｇn

Ｕsｉngthefirst－order　modelof（４）　fortｈeopeｎ-loｏp　transfer　functｉoｎ　Gaｑ（s）aｎdａssumingforthemomeｎtthaｔlinｅａrconｔroloftheheateｒｐｏwｅｒ　oｕtｐutq（t）isｐossｉbｌｅ,　ｔhe　bｌockｄiａgrａｍoｆFigｕｒe6ｒepresenｔsthecｌｏsed-lｏopｓyｓtｅm.Td（s）iｓtｈeｄesired,oｒ　set-ｐ