EE475Automa,cControl

Systems

Fall2017MWF11:00-11:50am

1012CooverHall

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–  NicolaElia,3131CooverHall–  nelia@iastate.edu;294-6277–  OfficeHour:12-1MWF–  Oranyother-memutuallyconvenient–  Pleaseinclude"EE475"inthesubjectlineinallemailcommunica,ons

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FinalGradeWeigh-ngSchedule

•  Homeworkaverage:15%(1Hwcanbelate.LowestHWscorediscarded)

•  Midtermexam1:20%•  Midtermexam2:20%•  Finalexam:30%•  Quizzes:15%(onelowestscoresdiscarded)•  Discre,onarybonus:0-5%(classpar,cipa,on,improvementtrend)

•  FixedGradingScale:q A:90–100% A–:85–89.9%q B+:80–84.9% B:75–79.9% B–:70–74.9%q C+:65–69.9% C:60–64.9% C–:50–55.9%q F:<50%

CatalogDescrip-on

•  EE475.Automa-cControlSystems.(3-0)Cr.3.F.Prereq:324.Stabilityandperformanceanalysisofautoma,ccontrolsystems.Thestatespace,rootlocus,andfrequencyresponsemethodsforcontrolsystemsdesign.PIDcontrolandlead-lagcompensa,on.Computertoolsforcontrolsystemanalysisanddesign.Nonmajorgraduatecredit.

Prerequisitebytopics

•  KnowledgeandproficiencyinMatlab•  Conceptandsolu,onoflinearordinarydifferen,alequa,ons

•  Laplacetransformanditsapplica,ons•  Poles,zeros,transferfunc,ons,frequencyresponse,rootlocus,Bodeplots,Nyquistplot

•  Vectorsandmatrices•  Complexnumbers

MainOBJECTIVES•  Oncomple,onofEE475,thestudentwillbeabletodothefollowingeitherbyhandorwith

thehelpofcomputa,ontoolssuchasMatlab:•  Definethebasicterminologiesusedincontrolssystems•  Explainadvantagesanddrawbacksofopen-loopandclosedloopcontrolsystems•  Obtainmodelsofsimpledynamicsystemsinordinarydifferen,alequa,on,transferfunc,on,statespace,

orblockdiagramform•  Obtainoveralltransferfunc,onofasystemusingeitherblockdiagramalgebra,orMatlabtools.•  Computeandpresentingraphicalformtheoutputresponseofcontrolsystemstotypicaltestinputsignals•  Explaintherela,onshipbetweensystemoutputresponseandtransferfunc,oncharacteris,csorpole/

zeroloca,ons•  Determineproper,esoftheclosedloopsystemformtheopenloopstystem.•  Determinethestabilityofaclosed-loopcontrolsystemsusingMatlabtools,theRouth-Hurwitzcriteria,

theroot-locusandtheNyquistcriterion.•  Analyzetheclosedloopstabilityandperformanceofcontrolsystemsbasedonopen-looptransfer

func,onsusingthefrequencyresponsetechniques•  DesignPIDorlead-lagcompensatortoimprovetheclosedloopsystemstabilityandperformanceusingthe

frequencyresponsetechniques

TopicsCovered•  Reviewofsignalsystemsconceptsandtechniquesasappliedtocontrolsystems•  Introduc,ontomodelingofdynamicalsystemsusingode’sandstatespace

methods.•  LinearTimeInvariantsystems•  ModelingofLTIcontrolsystemstransferfunc,onsandblockdiagrams.•  Blockdiagramsmanipula,ons•  Proper,esandlimita,onofLTIfeedbacksystems•  BasicanalysisanddesignprinciplesofLTIfeedbacksystemsinthefrequency

domain.•  Introduc,ontouncertaintyanalysisandrobustness•  Analysisofdynamicresponseofcontrolsystems,includingtransientresponse,

steadystateresponse,andtrackingperformance.•  Closed-loopstabilityanalysisusingtheRouth-Hurwitzcriterion,RootLocus,

Nyquistcriterion.•  Stabilityandperformanceanalysisusingthefrequencyresponsetechniques•  Controlsystemdesignusingthefrequencyresponsetechniques•  Ifthereis,me,Controlsystemdesignusingthestatespacetechniques

Studentbehaviorexpecta,ons•  FullaDendanceexpected,exceptwithprior-no,fiedexcuses

•  On-,mearrival•  Ac,vepar,cipa,on

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Collabora-onAndHelpingEachOther

•  Fortasksintendedforgroupwork,youareexpectedtofindapartnerandsharethetasksamongthegroupmembers.Inagroupproject,effec,veteamworkiscri,caltomaximizetheproduc,vityofthewholegroup.InthesubmiDedwork,iden,fycomponentsandindicatepercentagecontribu,onbyeachmembertoeachcomponent.

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TypesofControlSystems

➸ Open-Loop– Simplecontrolsystemwhichperformsitsfunc,onwith-outconcernsforini,alcondi,onsorexternalinputs.

– Mustbecloselymonitored.

➸ Closed-Loop(feedback)– Usestheoutputoftheprocesstomodifytheprocesstoproducethedesiredresult.

– Con,nuallyadjuststheprocess.

System 2 System 1 Open Loop

System 2 System 1 Closed Loop

Feedback is ubiquitous in natural and engineered systems

Figure 1-1 Speed control system.

ControlSystemTerminology

•  Input-Excita,onappliedtoacontrolsystemfromanexternalsource.

•  Output-Theresponseobtainedfromasystem

•  Feedback-Theoutputofasystemthatisreturnedtomodifytheinput.

•  Error-Thedifferencebetweenthereferenceinputandtheoutput.

•  FeedbackControl-sensing+computa,on+actua,on

Why do we use feedback?

Robustness to Uncertainty through Feedback Feedback allows high performance in the presence of uncertainty Example: repeatable performance of amplifiers with 5X component variation Key idea: accurate sensing to compare actual to desired, correction through computation and actuation

Design of Dynamics through Feedback Feedback allows the dynamics of a system to be modified Example: stability augmentation for highly agile, unstable aircraft Key idea: interconnection gives closed loop that modifies natural behavior

X-29 experimental aircraft

AdvantagesofaClosed-LoopFeedbackSystem

➸ ReducedSensi-vitytoDisturbanceByselfcorrec,ngitminimizeseffectsofsystemchanges.

➸ IncreasedAccuracyIncreasedabilitytoreproduceoutputwithvariedinput.

➸ SmoothingandFilteringSysteminducednoiseanddistor,onarereduced.

➸ IncreasedBandwidthProducessat.responsetoincreasedrangeofinputchanges.

Control = Sensing + Computation + Actuation

Sense Vehicle Speed

Compute Control “Law”

Actuate Gas Pedal

In Feedback “Loop”

Goals Stability: system maintains desired operating point (hold steady speed) Performance: system responds rapidly to changes (accelerate to 65 mph) Robustness: system tolerates perturbations in dynamics (mass, drag, etc)

FeedbackSystems

Sense

Compute

Actuate •  Control=

Sensing+Computa,on+Actua,on

•  FeedbackPrinciples–  Robustnessto

Uncertainty–  DesignofDynamics

•  Manyexamplesoffeedbackandcontrolinnatural&engineeredsystems:

BIO

BIO ESE

ESE

CS

ModernEngineeringApplica,onsofControl•  FlightControlSystems

–  Moderncommercialandmilitaryaircrarare“flybywire”

–  Autolandsystems,unmannedaerialvehicles(UAVs)arealreadyinplace

•  Robo,cs–  Highaccuracyposi,oningfor

flexiblemanufacturing–  Remoteenvironments:space,

sea,non-invasivesurgery,etc.

•  ChemicalProcessControl–  Regula,onofflowrates,

temperature,concentra,ons,etc.

–  Long,mescales,butonlycrudemodelsofprocess

•  Communica,onsandNetworks–  Amplifiersandrepeaters–  Conges,oncontrolofthe

Internet–  Powermanagementforwireless

communica,ons•  Automo,ve

–  Enginecontrol,transmissioncontrol,cruisecontrol,climatecontrol,etc

–  Luxurysedans:12controldevicesin1976,42in1988,67in1991

•  ANDMANYMORE...

AmodernFeedbackControlSystem

AGermanan,-aircrar88mmgunwithitsfire-controlcomputerfromWorldWarII.DisplayedintheCanadianWarMuseum.

Present Position

Future Position

Ship’s Heading Range Change

Bearing Change

Present Bearing

Fire Control Problem

SolvingtheFireControlProblem

Continuously Measure Present Target Position

Stabilize Measured Quantities

Compute Relative Target Velocity

Ballistic Calculations

Relative Motion Calculations

Time of Flight

Future Target Position

Prediction Procedure

Unstabilized Launch Angles

Environmental Inputs

Launch Angles (Stabilized)

Weapons Positioning orders

Temperature control system.

Block diagram of an engineering organizational system.

Conceptualmethodofefficientwaterextrac,onusingsolarpower.

a. system concept; b. detailed layout; c. schematic; d. functional block diagram

Antenna azimuth position control system:

Importantcomponentsofthesun-trackingcontrolsystem.

Limita,onsoffeedback

•  Feedbackaffectsstability!•  Itcanmakeasystemunstable

•  Feedbacksystemsaremorecomplextounderstand,designandimplement.

•  Therearesomethingsfeedbackcannotdo•  Performancestabilitytradeoffs

Responseofaposi,oncontrolsystemshowingeffectofhighandlowcontrollergainonthe

outputresponse

High gain; fast but oscillating

Control goal; fast reaction, lower overshoot, less settling time

ControlSystemsHistory

•  WaD,steamenginespeedcontrolgovernor•  Black,feedbackamplifiers•  Minorsky,shipsteeringstability•  Nyquist,closed-loopstabilityfromopen-loop•  Hazen,Servomechanisms•  Bode,Bodeplot,andBPbasedcontroldesign•  Evans,rootlocusplot,RLbaseddesign•  Kalman,statespace,controllability,Kalmanfilter•  Anderson…,linearop,malcontrol

•  Bellman,dynamicprogramming•  Pontryagin,maximumprinciple•  Lyapunov,nonlinearsystems•  Sastry…,adap,vecontrol•  Arimoto,learningcontrol•  Doyle…,robustcontrol•  Byrnes/Isidori,nonlinearregula,on•  Devasia/Chen/Paden,stableinversion•  Kokotovic,backstepping

ControlSystemsHistory

Commonlanguageacrossdisciplines

Feedback control is everywhere In this course you will learn the basic analysis and design principles of

feedback systems