电子技术专业英语教学课件作者何茗unit9.ppt

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1、Unit9BriefIntroductiontoControlSystemsWhycontrolsystemisused?Whydoyouneedacontrolsystematall?Considerthefollowing.Whatgoodisanovenifyoucan’tcontrolthetemperature?Whatgoodisanairplaneifyouareapilotandyoucan’tmakeitgowhereyouwantittogo?Whatgoodisachemicalproductsproductionlineifyoucan’tcontrol

2、temperature,pressureandpHintheprocessandyouendupmakingtonsofgarbage?下一页返回Unit9BriefIntroductiontoControlSystemsInfact,automaticcontrolhasplayedasignificantroleintheadvancementofengineeringandscience.Inadditiontoitsextremeimportanceinspacevehicle,missileguidance,andaircraftpilotingsystems,etc

3、.,automaticcontrolhasbecomeanimportantandintegralpartofmodernmanufacturingandindustrialprocesses.下一页上一页返回Unit9BriefIntroductiontoControlSystemsSinceadvancesinthetheoryandpracticeofautomaticcontrolprovidemeansforattainingoptimalperformanceofdynamicsystems,improvethequalityandlowerthecostofpro

4、duction,expandtheproductionrate,relievethedrudgeryofmanyroutine,repetitivemanualoperations,etc.,mostengineersandscientistsmustnowhaveagoodunderstandingofthisfield.下一页上一页返回Unit9BriefIntroductiontoControlSystemsThehistoryofautomaticcontrolThefirstsignificantworkinautomaticcontrolwasJamesWatt’s

5、centrifugalgovernorforthespeedcontrolofasteamengineintheeighteenthcentury.OthersignificantworksintheearlystagesofthedevelopmentofthecontroltheorywereduetoMinorsky,Hazen,andNyquist,amongmanyothers.下一页上一页返回Unit9BriefIntroductiontoControlSystemsDuringthedecadeofthe1940s,frequencyresponsemethod

6、smadeitpossibleforengineerstodesignlinearfeedbackcontrolsystemsthatsatisfiedperformancerequirements.Fromtheendofthe1940stoearly1950s,therootlocusmethodincontrolsystemdesignwasfullydeveloped.下一页上一页返回Unit9BriefIntroductiontoControlSystemsThefrequencyresponseandtherootlocusmethods,whicharethec

7、oreofclassicaltheory,leadtosystemsthatarestableandsatisfyasetofmoreorlessarbitraryperformancerequirements.Suchsystemsare,ingeneral,notoptimalinanymeaningfulsense.Sincethelate1950s,theemphasisoncontroldesignproblemshasbeenshiftedfromthedesigno