机械类数控外文翻译外文文献英文文献数控dhcx.docx

Numeericcal ConntroolOne of thee moost funndammenttal connceppts in thee arrea of advvancced mannufaactuurinng ttechhnollogiies is nummeriicall coontrrol (NCC).PPrioor tto tthe advventt off NCC, aall macchinne ttoolls wweree maanuaal ooperrateed aand conntroolleed. Amoong thee maany limmitaatioons asssociiateed wwithh maanuaal cconttroll maachiine toools, peerhaaps nonne iis mmoree prromiinennt tthann thhe llimiitattionn off opperaatorr skkillls. Witth mmanuual conntrool, thee quualiity of thee prroduuct is dirrecttly rellateed tto aand limmiteed tto tthe skiillss off thhe ooperratoor . Nuumerricaal cconttroll reepreesennts thee fiirstt maajorr sttep awaay ffromm huumann coontrrol of macchinne ttoolls.Numeericcal conntrool mmeanns tthe conntrool oof mmachhinee tooolss annd ootheer mmanuufaccturringg syysteems thooughh thhe uuse of preereccordded, wrrittten symmbollic insstruuctiionss. RRathher thaan ooperratiing a mmachhinee toool, ann NCC teechnniciian wriitess a proograam tthatt isssuees ooperratiionaal iinsttrucctioons to thee maachiine toool, Forr a macchinne ttooll too bee nuumerricaallyy coontrrollled , iit mmustt bee innterrfacced witth aa deevicce ffor acccepttingg annd ddecoodinng tthe p2oograammeed iinsttrucctioons, knnownn ass a reaaderr.Numeericcal conntrool wwas devveloopedd too ovverccomee thhe llimiitattionn off huumann opperaatorr , andd itt haas ddonee soo . Nummeriicall coontrrol macchinnes aree moore acccuraate thaan mmanuuallly ooperrateed mmachhinees , thhey cann prroduuce parrts morre uunifformmly , ttheyy arre ffastter, annd tthe lonng-rrun tooolinng ccostts aare lowwer . TThe deevellopmmentt off NCC leed tto tthe devveloopmeent of sevveraal ootheer iinnoovattionns iin mmanuufaccturringg teechnnoloogy:1. Elecctriicall diischhargge mmachhiniing.2. Laseer ccutttingg.3. Elecctroon bbeamm weeldiing.Numeericcal conntrool hhas alsso mmadee maachiine toools morre vverssatiile thaan ttheiir mmanuuallly ooperrateed ppreddeceessoors. Ann NCC maachiine toool ccan auttomaaticcallly pprodducee a widde vvariietyy off paar4ss , eacch iinvoolviing an asssorttmennt oof uundeertaake thee prroduuctiion of prooduccts thaat wwoulld nnot havve bbeenn feeasiiblee frrom an ecoonommic perrspeectiive usiing mannuallly conntroolleed mmachhinee tooolss annd pproccessses.Likee soo maany advvancced tecchnoologgiess , NC wass boorn in thee laaborratooriees oof tthe Masssacchussettts IInsttituute of Tecchnoologgy . Thhe cconcceptt off NCC waas ddeveelopped in thee eaarlyy 19950ss wiith funndinng pprovvideed bby tthe U.SS Aiir FForcce .In itss eaarliiestt sttagees , NCC maachiiness weere ablle tto mmakee sttraiightt cuuts effficiienttly andd efffecctivvelyy.Howeeverr ,ccurvved patths weere a pprobblemm beecauuse thee maachiine toool hhad to be proograammeed tto uundeertaake a sseriies of horrizoontaal aand verrticcal steeps to prooducce aa cuurvee. TThe shoorteer iis tthe strraigght linnes makkingg upp thhe sstepp ,tthe smooothher is 4hee cuurvee . Eacch llinee seegmeent in thee sttepss haad tto bbe ccalcculaatedd.Thiss prrobllem ledd too thhe ddeveeloppmennt iin 119599 off thhe AAutoomatticaallyy Prrogrrammmed Toools (APPT) lannguaage forr NCC thhat usees sstattemeentss siimillar to Engglissh llangguagge tto ddefiine thee paart geoomettry, deescrribee thhe ccutttingg toool connfigguraatioon, andd sppeciify thee neecesssarry mmotiionss. TThe devveloopmeent of thee APPT llangguagge wwas a mmajoor sstepp foorwaard in thee fuurthher devveloopmeent of NC tecchnoologgy. Thee orrigiinall NCC syysteem wweree vaastlly ddifffereent froom tthosse uusedd puunchhed papper , wwhicch wwas latter to repplacced by maggnettic plaastiic ttapee .AA taape reaaderr waas uusedd too innterrpreet tthe insstruuctiionss wrrittten on thee taape forr thhe mmachhinee .TTogeetheer, alll /ff thhis reppressentted giaant steep fforwwardd inn thhe cconttroll off maachiine toools . HHoweeverr ,ttherre wweree a nummberr off prrobllemss wiith NC at thiis ppoinnt iin iits devveloopmeent.A maajorr prrobllem wass thhe ffraggiliity of thee puunchhed papper tappe mmediium . IIt wwas commmonn foor tthe papper conntaiininng tthe proograammeed iinsttrucctioons to breeak or teaar dduriing a mmachhiniing proocesss, Thhis proobleem wwas exaacerrbatted by thee faact thaat eeachh suucceessiive timme aa paart wass prroduucedd onn a macchinne ttooll, tthe papper tappe ccarrryinng tthe proograammeed iinsttrucctioons hadd too reerunn thhougght thee reeadeer . Iff itt waas nneceessaary to prooducce 1100 coppiess off a givven parrt , itt waas aalsoo neecesssarry tto rrun thee paaperr taape thooughht tthe reaaderr 1000 ssepaaratte ttimees . Frragiile papper tappes simmplyy coouldd noot wwithhstaand thee riigorrs oof sshopp flloorr ennvirronmmentt annd tthiss kiind of reppeatted usee.Thiss leed tto tthe devveloopmeent of a sspecciall maagneeticc taape . WWherreass thhe ppapeer ttapee caarriied thee prrogrrammmed insstruuctiionss ass a serriess off hooless puunchhed in thee taape , ttheTThiss moost impporttantt off thhesee waas tthatt itt waas ddiffficuult or impposssiblle tto cchannge thee innstrructtionns eenteeredd onn thhe ttapee . To makke eevenn thhe mmostt miinorr addjusstmeentss inn a proograam oof iinsttrucctioons, itt waas nneceessaary to intterrruptt maachiininng ooperratiionss annd mmakee a neww taape. Itt waas aalsoo sttilll neecesssarry tto rrun thee taape thooughht tthe reaaderr ass maany timmes as theere werre ppartts tto bbe pprodduceed . Foortuunattelyy, ccompputeer ttechhnollogyy beecomme aa reealiity andd sooon sollvedd thhe pprobblemms oof NNC, asssociiateed wwithh puunchhed papper andd pllasttic tappe.The devveloopmeent of a cconcceptt knnownn ass nuumerricaal cconttroll (DDNC) soolvee thhe ppapeer aand plaastiic ttapee prrobllemss asssocciatted witth nnumeericcal conntrool bby ssimpply eliiminnatiing tappe aas tthe meddiumm foor ccarrryinng tthe proograammeed iinsttrucctioons . IIn ddireect nummeriicall coontrrol, maachiine toools aree tiied, viia aa daata traansmmisssionn liink, too a hosst ccompputeer aand fedd too thhe mmachhinee toool as neeededd viia tthe datta ttrannsmiissiion linnkagge. Dirrectt nuumerricaal cconttroll reepreesenntedd a majjor steep fforwwardd ovver punncheed ttapee annd pplassticc taape. Hoowevver ,itt iss suubjeect to thee saame limmitaatioon aas aall tecchnoologgiess thhat deppendd onn a hosst ccompputeer. Wheen tthe hosst ccompputeer ggoess doown , tthe macchinne ttoolls aalsoo exxperriennce dowwn ttimee . Thiis pprobblemm leed tto tthe devveloopmeent of commputter nummeriicall coontrrol.The devveloopmeent of thee miicrooproocesssorr alllowwed forr thhe ddeveeloppmennt oof pproggrammmabble loggic conntroolleers (PLLC) andd miicroocommputterss . Theese twoo teechnnoloogiees aalloowedd foor tthe devveloopmeent of commputter nummeriicall coontrrol (CNNC).Witth CCNC , eeachh maachiine toool hhas a PPLC or a mmicrrocoompuuterr thhat serrvess thhe ssamee puurpoose. Thhis alllowss prrogrramss too bee innputt annd sstorred at eacch iindiividduall maachiine toool. CNCC soolveed tthe proobleems asssociiateed ddownntimme oof tthe hosst ccompputeer , buut iit iintrroduucedd annothher proobleem kknowwn aas ddataa maanaggemeent . TThe samme pproggramm miightt bee looadeed oon tten diffferrentt miicroocommputterss wiith no commmunnicaatioon aamonng tthemm. TThiss prrobllem is in thee prroceess of beiing sollvedd byy loocall arrea nettworrks thaat cconnnecttDiggitaal SSignnal ProocesssorrsTherre aare nummeroous sittuattionns wwherre aanallog siggnalls tto bbe pproccesssed in manny wwayss, llikee fiilteerinng aand speectrral anaalyssis , DDesiigniing anaalogg haardwwaree too peerfoorm theese funnctiionss iss poossiiblee buut hhas beccomee leess andd prractticaal, duee too inncreeaseed pperfformmancce rrequuireemennts, fllexiibillityy neeedss , andd thhe nneedd too cuut ddownn onn deevellopmmentt/teestiing timme .It is in othher worrds diffficcultt pmm deesiggn aanallog harrdwaare anaalyssis of siggnalls.The actt off saampllingg ann siignaal iintoo thhehaat aare speeciaalissed forr emmbedddedd siignaal pproccesssingg opperaatioons , aand succh aa prroceessoor iis ccallled a DDSP, whhichh sttandds ffor Diggitaal SSignnal Proocesssorr . Todday theere aree huundrredss off DSSP ffamiiliees ffromm ass maany mannufaactuurerrs, eacch oone dessignned forr a parrticculaar ppricce/pperfformmancce/uusagge ggrouup. Manny oof tthe larrgesst mmanuufaccturrerss, llikee Teexass Innstrrumeentss annd MMotoorolla, offfer botth sspeccialliseed DDSPs forr ceertaain fieeldss liike mottor-conntrool oor mmodeems ,annd ggeneerall hiigh-perrforrmannce DSPPs thaat ccan perrforrm bbroaad rrangges of proocesssinng ttaskks. Devveloopmeent kitts aan sofftwaare aree allso avaailaablee , andd thheree arre ccomppaniies makkingg sooftwwaree deevellopmmentt tooolss foor DDSPs tthatt alllowws tthe proograammeer tto iimpllemeent commpleex pproccesssingg allgorrithhms usiing simmplee “ddragg nn ddropp” mmethhodoologgiess.DSPs mmoree orr leess falll iintoo twwo ccateegorriess deepenndinng oon tthe undderllyinng aarchhiteectuure-fixxed-poiint andd flloattingg-poointt. TThe fixxed-poiint devvicees ggeneerallly opeeratte oon 116-bbit worrds, whhilee thhe ffloaatinng-ppoinnt ddeviicess opperaate on 32-40 bitts ffloaatinng-ppoinnt wwordds. Neeedleess to sayy , thee fiixedd-poointt deevicces aree geenerrallly ccheaaperr . Anootheer iimpoortaant arcchittectturaal ddifffereencee iss thhat fixxed-poiint proocesssorrs ttendd too haave an acccumuulattor arcchittectturee, wwithh onnly onee “ggeneerall puurpoose” reggistter , mmakiing theem qquitte ttriccky to proograam aand morre iimpoortaantlly ,makkingg C-commpillerss innherrenttly ineeffiicieent. Flloattingg-poointt DSSPss beehavve mmoree liike commmonn geenerral-purrposse CCPUs ,witth rregiisteer-ffilees.Therre aare thoousaandss off diiffeerennt DDSPs oon tthe marrkett, aand it is diffficcultt taask finndinng tthe mosst ssuittablle DDSP forr a proojecct. Thee beest wayy iss prrobaablyy too seet uup aa coonsttraiint andd wiishllistt, aand tryy too coompaare thee prroceessoors froom tthe bigggesst mmanuufaccturrerss aggainnst it.The “biig ffourr” mmanuufaccturrerss off DSSPs: Teexass Innstrrumeentss, MMotoorolla, AT&&T aand Anaalogg Deevicces.Digiitall-too-annaloog cconvverssionnIn tthe casse oof MMPEGG-Auudioo deecoddingg , diggitaal ccomppresssedd daata is fedd innto thee DSSP wwhicch pperfformms tthe deccodiing , tthenn thhe ddecoodedd saamplles havve tto bbe cconvvertted bacck iintoo thhe aanallog dommainn , andd thhe rresuultiing siggnall feed aan aampllifiier or simmilaar aaudiio eequiipmeent . TThiss diigittal to anaalogg coonveersiion (DCCA) is perrforrmedd byy a cirrcuiit wwithh thhe ssamee naame & DDifffereent DCAAs proovidde ddifffereent perrforrmannce andd quualiity , aas mmeassureed bby TTHD (Tootall haarmoonicc diistoortiion ), nummberr off biits, liineaaritty , sppeedd, ffiltter chaaraccterristticss annd ootheer tthinngs.The TMSS3200 faamilly DDQP of Texxas InsstruumenntsThe TLSS3200fammilyy coonsiistss off fiixedd-poointt, ffloaatinng-ppoinnt, mulltipproccesssor diggitaal ssignnal proocesssorrs (DPPs) , aand foxxed-poiint DSPP coontrrolllerss. TTMS3320 DSPP haave an arcchittectturee deesiggnedd sppeciificcallly ffor reaal-ttimee siignaal pproccesssingg . Thee FF/C2240 is a nnumbber of theeC220000DSPP pllatfformm , andd iss opptimmizeed ffor conntrool aappllicaatioons. ThheCC24xx seeriees oof DDSP conntroolleers commbinnes thiis rreall-tiime proocesssinng ccapaabillityy wiith conntroolleer pperiipheeralls tto ccreaate an ideeal sollutiion forr coontrrol sysstemm apppliicattionns. Thee foolloowinng ccharractteriistiics makke tthe TMSS3200 faamilly tthe rigght chooicee foor aa wiide rannge of proocesssinng aappllicaatioons:- Verry fflexxiblle iinsttrucctioon sset- Inhhereent opeerattionnal fleexibbiliity -HHighh-sppeedd peerfoormaancee-IInnoovattivee paaralllell arrchiiteccturre-CCostt efffecctivveneessDeviicess wiithiin aa geenerratiion of thhe TTMS3320 fammilyy haave thee saame CPUU sttruccturre bbut diffferrentt onn-chhip memmoryy annd pperiipheerall coonfiigurratiionss. SSpinn-offf ddeviicess usse nnew commbinnatiionss off Onn-chhip memmoryy annd pperiipheeralls tto ssatiisfyy a widde rrangge oof nneedds iin tthe worrldwwidee ellecttronnicss maarkeet. By inttegrratiing memmoryy annd pperiipheeralls oontoo a sinnglee chhip , TTMS3320 devvicees rreduuce sysstemm coostss annd ssavee ciircuuit boaard spaace.The 16-bitt ,ffixeed-ppoinnt DDSP corre oof tthe C224x devvicees pprovvidees aanallog dessignnerss a diggitaal ssoluutioon tthatt dooes nott saacriificce tthe preecissionn annd pperfformmancce oof ttheiir ssysttem perrforrmannce cann bee ennhanncedd thhrouugh thee usse oof aadvaanceed cconttroll allgorrithhms forr teechnniquues succh aas aadapptivve cconttroll , Kallmann fiilteerinng , annd sstatte cconttroll. TThe C224x DSPP coontrrolller offfer relliabbiliity andd prrogrrammmabiilitty . Annaloog cconttroll syysteems, onn thhe ootheer hhandd ,aare harrdwiiredd sooluttionns aand cann exxperriennce perrforrmannce deggraddatiion duee too aggingg , commponnentt toolerrancce, andd drriftt.The higgh-sspeeed ccenttrall prroceessiing uniit (CPUU) aalloows thee diigittal dessignner to proocesss aalgooritthmss inn reeal timme rrathher thaan aapprroxiimatte rresuultss wiith loook-uup ttablles. Thhe iinsttrucctioon sset of theese DSPP coontrrolllerss, wwhicch iincoorpoorattes botth ssignnal proocesssinng iinsttrucctioons andd geenerral-purrposse cconttroll fuuncttionns, couupleed wwithh thhe eexteensiive devveloopmeent timme aand prooviddes thee saame easse oof uuse as traadittionnal 8-aand 16-bitt miicrooconntroolleers. Thhe iinsttrucctioon sset alsso aalloows youu too reetaiin yyourr sooftwwaree innvesstmeent wheen mmoviing froom ootheer ggeneerall-puurpooseC2xxx ggeneerattionn ,ssourrce codde ccomppatiiblee wiith theeC22x ggeneerattionn , andd uppwarrdlyy soourcce ccodee coompaatibble witth tthe C55x ggeneerattionn off DSSPs froom TTexaas IInsttrummentts.The C224x arcchittectturee iss allso welll-ssuitted forr prroceessiing conntrool ssignnals