SERVOCONTROLSYSTEMS1:DCServomechanismsElkeLaubwald:VisitingConsultant,controlsystemsprinciples.co.ukABSTRACT:Thisisoneofaseriesofwhitepapersonsystemsmodelling,analysisandcontrol,preparedbyControlSystemsPrinciples.co.uktogiveinsightsintoimportantprinciplesandprocessesincontrol.Incontrolsystemsthereareanumberofgenericsystemsandmethodswhichareencounteredinallareasofindustryantechnology.Thesewhitepapersaimtoexplaintheseimportantsystemsandmethodsinstraightforwardterms.Thewhitepapersdescribewhatmakesaparticulartypeofsystem/methodimportant,howitworksandthendemonstrateshowtocontrolit.Thecontroldemonstrationsisperformedusingmodelsofrealsystemsdesignedbyourfounder-PeterWellstead,anddevelopedformanufacturebyTQEducationandTrainingLtdintheirCErangeofequipment.Wherepossibleresultsfromtherealsystemareshown.Thiswhitepaperisabouttheuniversallyused‘workhorse’ofelectro-mechanicalsystems–theDCservocontrolsystemorservomechanism.1.WhatisaServoControlSystemandservomotor? Aservocontrolsystemisoneofthemostimportantandwidelyusedformsofcontrolsystem.Anymachineorpieceofequipmentthathasrotatingpartswillcontainoneormoreservocontrolsystems.Thejobofthecontrolsystemmayinclude:Maintainingthespeedofamotorwithincertainlimits,evenwhentheloadontheoutputofthemotormightvary.Thisiscalledregulation.Varyingthespeedofamotorandloadaccordingtoanexternallysetprogrammeofvalues.Thisiscalledsetpoint(orreference)tracking.Ourdailylivesdependuponservocontrollers.Anywherethatthereisanelectricmotortherewillbeaservocontrolsystemtocontrolit.Servocontrolisveryimportant.Theeconomyoftheworlddependsuponservocontrol(thereareotherthingstobesure–butstaywithmeonthecontroltheme).Manufacturingindustrywouldceasewithoutservosystemsbecausefactoryproductionlinescouldnotbecontrolled,transportationwouldhaltbecauseelectrictractionunitswouldfail,computerswouldceasebecausediskdriveswouldnotworkproperlyandcommunicationsnetworkswouldfailbecausenetworkserversuseharddiskdrives.Youngpeoplewouldbecomeevenmoreunbearableandtheywouldcomplainmorethantheydonow,becausetheirmusicandgamessystemswillnotworkwithoutservocontrol.Servocontrolsystemsarethatimportantanditisvitaltoknowaboutthem.Sopayattentionandsitupstraight–youarenotonholidayandIamnotwritingthisforthegoodofmyhealth.Alsoknownastheimplementationofthemotorservomotor,theautomaticcontrolsystemfortheimplementationofcomponentstoconvertsignalsreceivedfromthemotorshaftangulardisplacementorangularvelocityoutput.DCandACservomotorisdividedintotwocategories,themainfeatureisthatwhenthesignalvoltageiszero,norotationofthephenomenon,theincreasingspeedwithuniformtorquedecreased.Servomotorstocontrolmechanicalservosystemintheoperationoftheenginecomponents.Isaservomotorsdevice.Servomotorcancontrolthespeed,positionaccuracyisveryaccurate.Thevoltagesignalintoatorqueandspeedtodrivethecontrolobject.Rotorspeedbytheinputsignalcontrol,andcanrespondrapidly,intheautomaticcontrolsystemfortheimplementationofcomponents,andhaselectricalandmechanicaltimeconstant,linearandhighinitiatingvoltagelow.2.ModellingaSimpleServoSystemBeforewecancontrolasystemwemustunderstandinmathematicaltermshowthesystembehaveswithoutcontrol.Thisissystemmodellinganditisafundamentalpartofourworkincontrolsystemsanalysis.Thiswhitepaperisaboutthesimplestformofservo–thedirectcurrent(DC)positioncontrolservomechanism.Itisimportantbecause,althoughitisthesimplestformofservomechanism,itisusedasthestartingpointforunderstandingallotherservosystemsThebasicformofaDCservosystemismadeofanelectricmotorwithanoutputshaftthathasaninertialloadJonit,andfrictioninthebearingsofthemotorandload(representedbytheconstantb).Therewillbeanelectricdrivecircuitwhereaninputvoltageu(t)istransformedbythemotorintoatorqueT(t)inthemotoroutputshaft.Usingsystemsmodellingideasformechanicalsystemsatorquebalancecanbewrittenbetweentheinputtorquefromthemotorandthetorquerequiredtoacceleratetheloadandovercomefriction.ThisisshownintheequationWhereistheangularpositionoftheservooutputshaft.ThecontrolobjectiveistocontroltheshaftPositionortheshaftvelocitytobesomedesirevalue.Theinputvoltageu(t)isrelatedtothetorqueT(t)againKandtheinertiadividedbythefrictioncoefficientisreferredtoasthesystemtimeconstant,whereτ=J/bSothesystemmodelbecomes:Inapracticalservosystemtherewillbeadditionalcomponentsofthemodelwhichareimportant.Manyofthesearetodowiththenonlinearitiesinthedriveamplifierandfrictioninthemechanicalcomponents.Themostimportantnonlinearitiesarethesaturationvoltageofthemotordriveamplifier,thedeadbandintheamplifier,theso-calledCoulombfrictionintherotatingmechanicalcomponentsandhysteresis(backlash)inanygearboxesthatmightbebetweenthemotorandtheload.Agoodcontrolsystemmustincludefeaturestodealwiththesenonlinearfeatures.Inthiswhitepaperwewillconcentrateonthelinearpartsoftheservosystemandonlyshowsomehintsofnon-linearissues.Thelinearpartoftheservosystemmodelcanbeputinthetransferfunctionform:Wherey(s)istheoutputshaftpositionandu(s)isthemotorinput.Kisthesystemgainandistthetimeconstant.AnimportantjobforthecontrolsystemsanalystistoknowhowtomeasurethevaluesofthegainsKandthetimeconstant.Tomakeiteasiertofollowinthiscasewecansaythatforexample,theCE110ServoTrainerhasbeendesignedtogiveagainofonebetweenthemotorinputandthemotorspeed,andanapproximategainofK2betweenthemeasuredspeedandthemeasuredshaftposition.Thenominalvalueofthetimeconstantis1.5.Sothetransferfunctionmodelcanbedecomposedintothetransferfunctionfromthemotorinputtothemotorspeedv(s),andthetransferfunctionfromthemotorspeedtotheoutputshaftposition.Manycontrolsystemsdesigntoolsuseastatespacerepresentationofthesystemmodel.Inservosystemsthestatesarethevelocityandpositionoftheservosystemoutputshaft.Rearrangingthesystemtransfermodelgivesthestatespaceform:Alsonotethattheservosystemmeasuredvariablesinthestatemodelarethepositionoftheshafty(usingapositionencoderorpotentiometer)andthevelocityv(usingaspeedencoder).Thelinearmodelsgivenabovearethebasisofthedesignofservocontrollers.Arealservohoweverhasnon-linearcomponentsthatinfluenceitsdynamicbehaviour.ThemainnonlinearitiesareCoulombfrictioninthemovingpartsandthedeadzoneandsaturationinthemotorinputamplifier.Thisisadvancedcontrolandwewillnotcoveritinthiswhitepaper.Servomainlyrelyonimpulsetolocate,basicallycanbeunderstood,theservomotorreceivesapulse,apulsewillrotatethecorrespondingpointofview,inordertoachievethedisplacement,becausetheservomotoritselfhasissuedapulsefunction,sotheservoEachmotortorotateapointofview,isissuedbythecorrespondingnumberofpulses,sothatthepulseandservomotorstoaccepttheformationoftheecho,orcalledclosed-loop,thisway,thesystemwillknowthenumberofpulsessenttotheservomotor,whilethenumberofreceivedpulsecameback,sothatwecanveryaccuratelycontrolthemotorrotation,inordertoachieveaccuratepositioning,canreach0.001mm.DCservomotorintobrushandbrushlessmotors.Brushmotorlowcost,simplestructure,startingtorque,widespeedrange,easycontrol,needtomaintain,buteasytomaintain(replacementcarbonbrushes),generateelectromagneticinterference,theenvironmentrequirements.Soitcanbeusedforcost-sensitivegeneralindustrialandcivilapplications.Brushlessmotor,smallsize,lightweight,largeoutput,fastresponse,highspeed,smallinertia,rotationalsmoothness,torqueandstability.Controlcomplex,easytoimplementintelligent,flexiblewayoftheirelectroniccommutation,thecommutationcanbesquarewaveorsinusoidalcommutation.Motormaintenance-free,highefficiency,lowoperatingtemperature,electromagneticradiationisverysmall,long-life,canbeusedforavarietyofenvironments.BrushlessACservomotorisdividedintosynchronousandasynchronousmotors,motioncontrolinthecurrentsynchronousmotorisgenerallyused,anditspowerrange,candoalotofpower.Largeinertia,themaximumrotationspeedislow,andwiththepowerincreasesrapidlydecreased.Thussuitableforapplicationsthatrunonlowspeedsteady.Servomotorrotorispermanentmagnet,thedrivecontroloftheU/V/Wthree-phasepowertoformfields,therotorinthemagneticfieldundertherotation,whilethemotorcomeswithencoderfeedbacksignaltothedrive,thedriveaccordingtothefeedbackvaluecomparedwiththetargetvalue,adjustingtheangleoftherotorrotation.Dependsontheaccuracyoftheservomotorencoderaccuracy(lines).

Question:ACservomotorsandbrushlessDCservomotorfunction,whatisthedifference?

A:ACservobetterbecauseasinewavecontrol,torqueripplesmall.DCservoisatrapezoidalwave.ButtheDCservoisrelativelysimple,cheap3.ExampleofaServoSystemThefigure1showstheCE110ServoTrainerfromTQEducationandTrainingLtd.Thisisaclassicandcomprehensiverepresentationoftheservocontrolproblem.Itcontainsallrelevantfeaturesthatcanbefoundinapracticalservosystem.Thecentresectionofthesystemarethemainhardwareelements,fromthelefttheyare:1.Theinertialload2.Thespeedsensor3.Anactiveload(inthiscaseagenerator,G)4.Theservomotor,M5.Anelectricclutchandgearbox(canyouseethepictureofagearsystemontheright?)6.Andunderthegearsystemistheoutputshaftwithapositionsensor.Theelectricclutchallowthepositionsystemtobedisconnectedtostudyvelocitycontrolproblems.Thegearboxisincludedbecauseservomechanismsforpositioncontrolveryoftenhavegearboxestoreducespeedandincreasetorque.Thegeneratorisincludedsothatcontrolundervariableloadcanbeinvestigated.Atthetopofthefrontpanelareelectronicversionsofallthenonlinearelementsthatcanbefoundinrealservos–theseareusedtoteachnonlinearcompensationandtounderstandwhattolookforinpracticalsituations.Wewillbeusingthelinearmotorwithinternalloadandpositionoutputthroughagearboxtoillustrateservocontrolinaction.Imightshowsomenonlinearbehaviourinthiswhitepaper,butthenagain,Imightnot–itdependsonhowniceyouaretomeasIsitonthiskeyboard,allthetimedreamingofmybeautifulmountainhomelandandmeinVerlobter.4.ServoSystemControllersTherearemany,manyalternativecontrollerdesigntheoriesthatcanbeusedtocontrolaservomechanism.Possiblytherearetoomany.Hereisalistofmostofthetechniques:1.Threeterm(PID)control2.VelocityFeedbackControl3.PhaseLeadCompensation4.StateFeedbackControl5.StateObserverImplementationandControl6.LinearQuadraticRegulator(LQR)7.LinearQuadraticGaussian(LQG)8.RobustControl9.SlidingModeandVariableStructureControl10.DeadBeatControlEachoftheabovecanbeimplementedasacontinoustimemethodoradigitalmethodbasedonZtransforms.Alsoitispossibletousetechniquessuchasfuzzycontrolanditsvariants.Abewilderingchoiceisitnot?Andwhatismore,allofthemcangiveanacceptableperformanceifdesignedwithcareandbyanexpert.Forexample,robustcontrolpotentiallygivesthebesttechnicalandpracticalresults,butanexpertisrequiredtoselectthedesignfactorsrequiredandtogetasimpleimplementablecontroller.5.IntroductionpermanentmagnetACservomotor80yearssincethe20thcentury,withtheintegratedcircuits,powerelectronicsandACvariablespeeddrivetechnology,permanentmagnetACservodrivetechnologywithoutstandingdevelopment,nationalelectricalmanufacturershavelaunchedtheirownwell-knownACservomotorandservodriveseriesandcontinuetoimproveandupdateproducts.ACservosystemhasbecomeacontemporaryhigh-performanceservosystemsthemaindevelopmentdirection,sothattheoriginalDCservofacingthecrisisofbeingeliminated.90yearslater,theworldhasbeencommercializedbyACservodigitalcontrolsystemisasinewavemotorservodrive.ACservodrivetherapiddevelopmentofthefieldinthetransmission.PermanentmagnetACservomotorcomparedwithDCservomotor,themainadvantagesare:⑴withoutbrushandcommutator,itisreliableandmaintenancerequirementsformaintenanceandlow.⑵coolingthestatorwindingmoreconvenient.⑶inertiaissmall,easy-toimprovethesystemfast.⑷adaptedtohigh-speedhightorqueworkingcondition.⑸underthesamepower,smallersizeandweight.SincetheGermanMANNESMANNofRexrothIndramatdivisioninthecompany'sHanoverTradeFair1978wasofficiallylaunchedMACpermanentmagnetACservomotoranddrivesystem,whichmarksthisnewgenerationofACservotechnologyhasenteredthepracticalstage.Tothelate20thcentury,80years,thecompanyhasacompletelineofproducts.Theservo-devicemarketareturningtotheexchangesystem.Earlyanalogsystemssuchaszero-drift,interference,reliability,accuracyandflexibilityinareassuchaslackofmotioncontrolisstillnotfullymeettherequirements,inrecentyearswiththemicroprocessor,thenewdigitalsignalprocessor(DSP)applicationstheemergenceofdigitalcontrolsystem,thecontrolsectioncanbecarriedoutentirelybythesoftware,calledJianghazyorTuanShenJingonlyfreshcoarsehempenfabric,valiantonlyShenofthepermanentmagnetACservosystem.Sofar,high-performanceservosystemsmostlyuseelectricalpermanentmagnetsynchronousACservomotor,controlthedrivetousemorefast,accuratepositioningoftheall-digitalservosystem.TypicalmanufacturerssuchasSiemensofGermany,theUnitedStatesandJapanKollmorgencompaniessuchasPanasonicandYaskawa.YaskawaElectrichaslaunchedasmall-scaleproductionofACservomotorsanddrives,inwhichDseriesforCNCmachinetools(maximumspeedof1000r/min,torqueis0.25~2.8Nm),Rseriesissuitablefortherobot(thehighestspeedof3000r/min,torqueis0.016~0.16Nm).LaunchedaftertheM,F,S,H,C,Gsixseries.9020thcentury,hasintroducedanewD-seriesandRseries.Rectangularwavedrivefromtheoldseries,8051tocontrolthesinewavedrive,80C,154CPUandgatearraychipcontrol,torqueripplefrom24%to7%,andimprovedreliability.Thus,theformationofonlyafewyears,eightseries(powerrangeof0.05~6kW)morecompletesystemtomeettheworkingmachinery,transportationagencies,weldingrobots,assemblyrobots,electroniccomponents,processingmachinery,printingpresses,highspeedwindingmachine,windingmachinesfordifferentneeds.CNCequipmenttoproducethefamousJapaneselawthatg(Fanuc)company,inthe20thcenturyhasintroducedthemid-80sSseries(13specifications),andLseries(5specifications)ofthepermanentmagnetACservomotor.LSerieshasasmallermomentofinertiaandthemechanicaltimeconstant,particularlyforapplicationsthatrequirefastresponseservosystem.OtherJapanesemanufacturers,suchas:MitsubishiMotors(HC-KFS,HC-MFS,HC-SFS,HC-RFSandHC-UFSseries),ToshibaSeiki(SMseries),OkumaIronWorks(BLseries),SanyoElectric(BLseries),standingstonesmotor(Sseries)andmanyothermanufacturershaveenteredthepermanentmagnetACservosystemfray.GermanyRexroth(Rexroth)TheMACIndramatDivisionSeriesACservomotorTotal7Frame92specifications.Germany'sSiemens(Siemens)'sIFT5seriesthree-phasepermanentmagnetACservomotorstandardandshortformisdividedintotwocategories,atotalof98speciesof8framesizespecifications.AllegedlythesameseriesACservomotorandDCservomotoroutputtorquecomparedIHUseries,whichweighsonly1/2,supportingthetransistorPWMdrive6SC61series,themostfor6-axismotorcontrol.Bosch(BOSCH)ferritemagnetsproducedtheSDseries(17standard)andrareearthpermanentmagnetoftheSEseries(8specs)ACservomotoranddrivecontrollerServodynSMseries.AmericanproductioncompaniesGettysservodeviceasGouldElectronics,onceadivisionof(MotionControlDivision),productionofM600seriesA600seriesACservomotorandservodrives.AfterthemergertotheAEG,Gettysnamerestored,theintroductionofA700all-digitalACservosystem.U.S.AB(ALLEN-BRADLEY)1326-basedproductioncompanydriverdivisionferritepermanentmagnetACservomotorandservocontrollerPWMAC1391.Framesizemotorsincluding3of30specifications.ID(IndustrialDrives)isafamousColeMorgan(Kollmorgen)ofindustrialdrivesdivision,hasproducedBR-210,BR-310,BR-510atotalof41specificationsofthethreeseriesofbrushlessservomotorandservoBDS3drive.Since1989,launchedanewseriesdesignedsolelydopedJianPirates(Goldline)permanentmagnetACservomotor,includingtheB(smallinertia),M(MiddleInertia)andEB(explosionproof)threecategories,10,20,40,60,80fiveframesizes,eachof42categoriesofspecifications,allusingNdFeBpermanentmagnet,torquerangeof0.84~111.2Nm,apowerrangeof0.54~15.7kW.SupportingthedrivehasBDS4(analog),BDS5(digitaltype,withpositioncontrol)andtheSmartDrive(digitaltype)ofthreeseries,themaximumcontinuouscurrentof55A.GoldlineSeriesrepresentscontemporaryartinpermanentmagnetACservotechnology.Ireland'sInlandformerlyadivisionofKollmorgenabroad,nowmergedintotheAEG,theproductionofDCservomotors,DCtorquemotorandservoamplifierisknown.ProductionBHT1100,2200,3300threeframesizesof17kindsofspecificationsofSmCopermanentmagnetACservomotorandeightcontrollers.FrenchAlsthomGroupfactoryinParisParvexLCseries(longform)andGCseries(short)14ACservomotorspecifications,andproductionAXODYNseriesofdrives.TheformerSovietUnionfortheCNCmachinetoolsandrobotsservocontroldevelopedtwoseriesofACservomotor.OneДByseriesusesferritemagnets,therearetwoframesizes,framesizesare3foreachcorelength,eachwithtwowindingdata,atotalof12specifications,acontinuoustorquerangeof7~35N.m.2ДByseriesusesrareearthpermanentmagnet,6framesize17specifications,thetorquerangeis0.1~170N.m,supportingthe3ДБcontroller.Inrecentyears,Panasonichasintroducedtheall-digitalACservosystembasedMINASseries,inwhichpermanentmagnetACservomotorwithMSMAseriesofsmallinertia-type,powerfrom0.03~5kW,atotalof18kindsofspecifications;theinertiatypewithMDMA,MGMA,MFMAthreeseries,thepowerfrom0.75~4.5kW,23kindsofspecifications,MHMAseriesoflargeinertiamotorpowerrangefrom0.5~5kW,7kindsofspecifications.Samsungdevelopedinrecentyears,all-digitalACservomotoranddrivesystem,whichFAGAACservomotorseriesofCSM,CSMG,CSMZ,CSMD,CSMF,CSMS,CSMH,CSMN,CSMXavarietyofmodels,thepowerfrom15W~5kW.Nowoftenused(Powerrate)Thiscomprehensiveindexastheservomotorqualityfactor,measuringavarietyofACandDCservomotorcontrastanddynamicresponseperformancesteppermotor.Continuousmotorpower,saidtherateofchange(rated)torqueandrotorinertiaratio.Changerateiscalculatedbypoweranalysis,thepermanentmagnetACservomotortechnologyindicatorsfortheUnitedStatesID,GoldlineSeriesisthebest,followedbyGermany'sSiemensinIFT5series.摘要：這是根據(jù)控制系統(tǒng)理論撰寫(xiě)的關(guān)與系統(tǒng)模型、分析和控制的一系列白皮書(shū)之一，目的在于給出一些重要的控制理論和控制過(guò)程?？刂葡到y(tǒng)中有很多通用的系統(tǒng)和方法被廣泛應(yīng)用于所有工業(yè)和科技領(lǐng)域。這本書(shū)旨在以簡(jiǎn)單的術(shù)語(yǔ)解釋這些重要的系統(tǒng)和方法。這本書(shū)闡述了什么使特殊類(lèi)型的系統(tǒng)或者方法重要，它是如何起作用然后說(shuō)明如何去控制它。在基于真實(shí)系統(tǒng)的模型,由我們公司的創(chuàng)始人設(shè)計(jì)的機(jī)型-彼得Wellstead，并為開(kāi)發(fā)由天晴教育和培訓(xùn)公司在其設(shè)備的CErange制造。這份白皮書(shū)是普遍使用“木馬”的電控機(jī)械式系統(tǒng)—直流伺服控制系統(tǒng)或servomechanism。1.什么是伺服控制系統(tǒng)？伺服控制系統(tǒng)是控制系統(tǒng)中最重要和最廣泛使用的形式之一。任何含有旋轉(zhuǎn)部分的機(jī)器或者設(shè)備都含有一個(gè)或者更多的伺服控制系統(tǒng)。伺服控制系統(tǒng)的主要功能可以概括如下：維持電機(jī)的速度在一定的限制值，即使電機(jī)負(fù)載的輸出改變了，這就是所謂的調(diào)節(jié)。依據(jù)程序設(shè)置的精確給定值來(lái)改變電機(jī)的速度和負(fù)載大小，這是所謂的設(shè)定點(diǎn)（或引用）的跟蹤。伺服控制器在我們?nèi)粘Ｉ钪衅鹬浅Ｖ匾淖饔茫灰须姍C(jī)的地方就會(huì)有伺服控制系統(tǒng)去控制它。世界的經(jīng)濟(jì)依賴(lài)于伺服控制（肯定還有其他的方面的，但留在我的控制主題）。如果沒(méi)有伺服系統(tǒng)，人工制造業(yè)將停止生產(chǎn)，因?yàn)楣S生產(chǎn)線不能受控制、信息的傳遞也將停止，因?yàn)殡妭鬏攩卧霈F(xiàn)問(wèn)題、電腦也將停止工作，因?yàn)榇疟P(pán)不能正常工作從而信息網(wǎng)絡(luò)的交換也將癱瘓，因?yàn)榫W(wǎng)絡(luò)也需要硬盤(pán)的驅(qū)動(dòng)。年輕人將變得更不堪，他們將更加抱怨他們所做的，因?yàn)槿绻麤](méi)有伺服系統(tǒng)，他們的音樂(lè)和游戲?qū)⒉荒苷＿M(jìn)行。既然伺服控制系統(tǒng)如此重要，那么掌握它也是非常重要。所以，坐直注意-----你不是在度假，我寫(xiě)這個(gè)不是為了我的身體健康。伺服電動(dòng)機(jī)又稱(chēng)執(zhí)行電動(dòng)機(jī)，在自動(dòng)控制系統(tǒng)中，用作執(zhí)行元件，它將所收到的電信號(hào)轉(zhuǎn)換成電動(dòng)機(jī)軸上的角位移或角速度輸出。伺服電機(jī)分為直流和交流伺服電動(dòng)機(jī)兩大類(lèi)，其主要特點(diǎn)是，當(dāng)信號(hào)電壓為零時(shí)無(wú)自轉(zhuǎn)現(xiàn)象，轉(zhuǎn)速隨著轉(zhuǎn)矩的增加而勻速下降。伺服電機(jī)在伺服系統(tǒng)中控制機(jī)械元件運(yùn)轉(zhuǎn)的發(fā)動(dòng)機(jī).是一種補(bǔ)助電機(jī)間接變速裝置。伺服電機(jī)可使控制速度,位置精度非常準(zhǔn)確。將電壓信號(hào)轉(zhuǎn)化為轉(zhuǎn)矩和轉(zhuǎn)速以驅(qū)動(dòng)控制對(duì)象。轉(zhuǎn)子轉(zhuǎn)速受輸入信號(hào)控制，并能快速反應(yīng)，在自動(dòng)控制系統(tǒng)中作執(zhí)行元件，且具有機(jī)電時(shí)間常數(shù)小、線性度高、始動(dòng)電壓低等特點(diǎn)。2.建一個(gè)以簡(jiǎn)單的伺服系統(tǒng)模型在我們控制一個(gè)系統(tǒng)之前我們必須在數(shù)學(xué)層面上了解該系統(tǒng)在沒(méi)有控制的情況下是如何工作的，這就是系統(tǒng)模型的建立，它是基于我們對(duì)控制系統(tǒng)的分析，這本書(shū)是關(guān)于一種最簡(jiǎn)單的伺服形式—直流位置伺服控制。這是重要的，因?yàn)椋m然它是最簡(jiǎn)單的伺服系統(tǒng)的形式，但它是學(xué)習(xí)其他伺服系統(tǒng)的基礎(chǔ)。一個(gè)直流伺服系統(tǒng)的基本形式是使用由一個(gè)電動(dòng)機(jī)的J加載遇上的具有慣性的輸出軸，并且在電機(jī)和負(fù)載（由常數(shù)b表示）的軸承上存在摩擦。其中一個(gè)輸入電壓u（t）由電動(dòng)機(jī)轉(zhuǎn)換成轉(zhuǎn)矩T（t）的電動(dòng)驅(qū)動(dòng)器電路電動(dòng)機(jī)輸出軸。使用系統(tǒng)的建模思路機(jī)械系統(tǒng)的??轉(zhuǎn)矩平衡可寫(xiě)入從電機(jī)的輸入轉(zhuǎn)矩和加速負(fù)載所需的轉(zhuǎn)矩之間克服摩擦。Y有以下方程表示：其中θ是伺服輸出軸的角度位置，控制對(duì)象是控制軸位置或軸速度在期望值。輸入電壓u（t）與一個(gè)增益K和慣性由摩擦劃分有關(guān)的轉(zhuǎn)??矩T（t）和一個(gè)被稱(chēng)為系統(tǒng)時(shí)間常數(shù)τ有關(guān)，其中τ=J/b這樣，系統(tǒng)模型變?yōu)椋涸谝粋€(gè)實(shí)際伺服系統(tǒng)將會(huì)有附加的組件對(duì)模型來(lái)說(shuō)是很重要的。這些很多都是工作于非線性驅(qū)動(dòng)放大器和機(jī)械之間的摩擦，最重要的非線形性存在于電機(jī)驅(qū)動(dòng)放大器的飽和電壓、在放大器的死區(qū)、轉(zhuǎn)動(dòng)的機(jī)械組成部分的所謂的庫(kù)侖摩擦和滯后作用(后退)也許在馬達(dá)和裝載之間的所有傳動(dòng)箱。一個(gè)好控制系統(tǒng)必須包括這些特征以處理這些非線性特點(diǎn)。在這份《白皮書(shū)》白皮書(shū)中,我們將重點(diǎn)放在伺服系統(tǒng)的線性部分和提示一些非線性部分。伺服系統(tǒng)模型的線性部分可以用以下傳遞函數(shù)表示：其中：是在輸出軸上位置，是電機(jī)輸入。k是系統(tǒng)增益，是時(shí)間常數(shù)。伺服系統(tǒng)分析器的一個(gè)重要工作是要道如何衡量增益K和時(shí)間常數(shù)。要使它更加容易跟隨這種情況我們可以舉例說(shuō)明如：CE110伺服教練員已經(jīng)設(shè)計(jì)出了電機(jī)輸入與速度之間的增益和一個(gè)在電機(jī)速度可轉(zhuǎn)軸位置之間的合適增益K=2，時(shí)間常數(shù)是1.5。因此傳遞函數(shù)模型可以被分解入從電機(jī)的輸入傳遞函數(shù)到電動(dòng)機(jī)轉(zhuǎn)速v和從電動(dòng)機(jī)轉(zhuǎn)速的傳遞函數(shù)到輸出軸如很多控制系統(tǒng)設(shè)計(jì)工具用狀態(tài)空間表示系統(tǒng)模型，在伺服系統(tǒng)中，狀態(tài)是速度和輸出位置，從傳遞函數(shù)變換到如下?tīng)顟B(tài)空間：還注意到,伺服系統(tǒng)測(cè)量變量在狀態(tài)模型中的位置的軸Y(使用一個(gè)位置編碼器或電位器)和速度v(使用一個(gè)轉(zhuǎn)速編碼器)。上面給定的線性模型的基礎(chǔ)上設(shè)計(jì)的伺服控制器。一個(gè)真正的伺服系統(tǒng)是含有能影響其動(dòng)態(tài)行為的非線性元件,。主要的非線性是運(yùn)動(dòng)中零件的庫(kù)侖摩擦、死區(qū)和電機(jī)輸入放大器的飽和區(qū)。這是先進(jìn)的控制我們將不包括在本書(shū)中。伺服主要靠脈沖來(lái)定位，基本上可以這樣理解，伺服電機(jī)接收到1個(gè)脈沖，就會(huì)旋轉(zhuǎn)1個(gè)脈沖對(duì)應(yīng)的角度，從而實(shí)現(xiàn)位移，因?yàn)?，伺服電機(jī)本身具備發(fā)出脈沖的功能，所以伺服電機(jī)每旋轉(zhuǎn)一個(gè)角度，都會(huì)發(fā)出對(duì)應(yīng)數(shù)量的脈沖，這樣，和伺服電機(jī)接受的脈沖形成了呼應(yīng)，或者叫閉環(huán)，如此一來(lái)，系統(tǒng)就會(huì)知道發(fā)了多少脈沖給伺服電機(jī)，同時(shí)又收了多少脈沖回來(lái)，這樣，就能夠很精確的控制電機(jī)的轉(zhuǎn)動(dòng)，從而實(shí)現(xiàn)精確的定位，可以達(dá)到0.001mm。直流伺服電機(jī)分為有刷和無(wú)刷電機(jī)。有刷電機(jī)成本低，結(jié)構(gòu)簡(jiǎn)單，啟動(dòng)轉(zhuǎn)矩大，調(diào)速范圍寬，控制容易，需要維護(hù)，但維護(hù)方便（換碳刷），產(chǎn)生電磁干擾，對(duì)環(huán)境有要求。因此它可以用于對(duì)成本敏感的普通工業(yè)和民用場(chǎng)合。無(wú)刷電機(jī)體積小，重量輕，出力大，響應(yīng)快，速度高，慣量小，轉(zhuǎn)動(dòng)平滑，力矩穩(wěn)定。控制復(fù)雜，容易實(shí)現(xiàn)智能化，其電子換相方式靈活，可以方波換相或正弦波換相。電機(jī)免維護(hù)，效率很高，運(yùn)行溫度低，電磁輻射很小，長(zhǎng)壽命，可用于各種環(huán)境。交流伺服電機(jī)也是無(wú)刷電機(jī)，分為同步和異步電機(jī)，目前運(yùn)動(dòng)控制中一般都用同步電機(jī)，它的功率范圍大，可以做到很大的功率。大慣量，最高轉(zhuǎn)動(dòng)速度低，且隨著功率增大而快速降低。因而適合做低速平穩(wěn)運(yùn)行的應(yīng)用。伺服電機(jī)內(nèi)部的轉(zhuǎn)子是永磁鐵，驅(qū)動(dòng)器控制的U/V/W三相電形成電磁場(chǎng)，轉(zhuǎn)子在此磁場(chǎng)的作用下轉(zhuǎn)動(dòng)，同時(shí)電機(jī)自帶的編碼器反饋信號(hào)給驅(qū)動(dòng)器，驅(qū)動(dòng)器根據(jù)反饋值與目標(biāo)值進(jìn)行比較，調(diào)整轉(zhuǎn)子轉(zhuǎn)動(dòng)的角度。伺服電機(jī)的精度決定于編碼器的精度（線數(shù)）。問(wèn)題：?jiǎn)柦涣魉欧姍C(jī)和無(wú)刷直流伺服電機(jī)在功能上有什么區(qū)別？答：交流伺服要好一些，因?yàn)槭钦也刂?，轉(zhuǎn)矩脈動(dòng)小。直流伺服是梯形波。但直流伺服比較簡(jiǎn)單，便宜。3.伺服系統(tǒng)的舉例圖1顯示CE110伺服培訓(xùn)師從TQ教育和培訓(xùn)有限公司，這是伺服控制問(wèn)題中一個(gè)典型又綜合的例子，它包含所有普通電機(jī)相關(guān)特征。這個(gè)系統(tǒng)的核心部分是主要的左邊的硬件元件它們是：1．慣性負(fù)載2．速度傳感器3．一個(gè)活動(dòng)的負(fù)載(在這種情況下一個(gè)發(fā)電機(jī),G)4．伺服電機(jī)5．一個(gè)電動(dòng)離合器和齒輪箱(您可以看到畫(huà)面的一個(gè)齒輪系統(tǒng)的上嗎?)6．并根據(jù)齒輪系統(tǒng)的輸出軸與一個(gè)位置傳感器。為了研究速度控制問(wèn)題，電動(dòng)離合器允許位置系統(tǒng)被斷開(kāi),齒輪箱是包括在內(nèi),因?yàn)樗欧恢每刂茩C(jī)制往往會(huì)有齒輪箱來(lái)減少速度和增加扭矩，發(fā)生器將會(huì)包括在內(nèi),根據(jù)控制變量可以進(jìn)行實(shí)現(xiàn)加載。在頂部的前面是電子版本的所有的非線性元件,用來(lái)教非線性補(bǔ)償，這些都可以在實(shí)際伺服電動(dòng)機(jī)中找到。我們將使用線性電機(jī)與內(nèi)部負(fù)載和位置輸出通過(guò)齒輪箱來(lái)說(shuō)明在伺服控制的行動(dòng)。我可能會(huì)顯示本白皮書(shū)中的一些非線性行為，但隨后再一次，我可能不會(huì)-這取決于你有多好是我，因?yàn)槲易谶@個(gè)鍵盤(pán)上，所有的時(shí)間都在做我美麗的山家園和炒面Verlobter的夢(mèng)。4.伺服系統(tǒng)控制器有很多很多其他控制器的設(shè)計(jì)理論,可用于控制伺服系統(tǒng)。可能是有太多了。下面是列出了的大部分的技術(shù):1．三種典型(PID)控制2．速度反饋控制3．前饋補(bǔ)償4．狀態(tài)反饋控制5．狀態(tài)補(bǔ)償控制6．二次方程線性穩(wěn)壓器(LQR)7．線性二次方程高斯(lqg)8．魯棒自適應(yīng)控制9．滑動(dòng)模式和變量結(jié)構(gòu)控制10。無(wú)差拍控制上述的每一項(xiàng)可以實(shí)現(xiàn)為一個(gè)連續(xù)時(shí)間方法或基于Z變換的數(shù)字方法。另外,還可能使用的技術(shù)(如模糊控制及其變形了的方法)。一個(gè)令人眼花撩亂選擇是吧?更有甚者,如果經(jīng)精心設(shè)計(jì)和專(zhuān)家的意見(jiàn)，它們都可以提供可接受的性能。例如,魯棒自適應(yīng)控制可能會(huì)提供最好的技術(shù)和實(shí)際的結(jié)果,但一個(gè)專(zhuān)家是需要根據(jù)的設(shè)計(jì)要求,選擇控制方法，設(shè)計(jì)一個(gè)簡(jiǎn)單可行控制器。5.永磁交流伺服電動(dòng)機(jī)簡(jiǎn)介20世紀(jì)80年代以來(lái)，隨著集成電路、電力電子技術(shù)和交流可變速驅(qū)動(dòng)技術(shù)的發(fā)展，永磁交流伺服驅(qū)動(dòng)技術(shù)有了突出的發(fā)展，各國(guó)著名電氣廠商相繼推出各自的交流伺服電動(dòng)機(jī)和伺服驅(qū)動(dòng)器系列產(chǎn)品并不斷完善和更新。交流伺服系統(tǒng)已成為當(dāng)代高性能伺服系統(tǒng)的主要發(fā)展方向，使原來(lái)的直流伺