IntroductionToControls-AutomotiveMechatronics

7/30/2019 IntroductionToControls-AutomotiveMechatronics

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IntroductiontoControls

forAutomotiveMechatronics


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Todayscarisarollingcomputer

Thereare30100microprocessorsinacar

controllingvarioussystems


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Themorecomplicatedsystemsarenot

juston/offcontrol

They

are

built

up

as

control

systems,

not

just

on/off

logic

systems.

A

control

systeminitssimplestformistheexpressionofawishandthenitsfulfillment.

Theinputtothecontrolsystemisawish,adesiredvalue. Forexample,ifthis

wereacruisecontrolsystemforacar,thiswouldbethedesiredspeed.

Theoutput

is

the

actual

value

of

the

parameter

that

the

control

system

controls. Foracruisecontrolsystem,thiswouldbetheactualspeedofthe

car.

Ifthecontrolsystemisworkingright,theactualvalueequalsthedesired

value.


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AcloserlookHowthishappensiswithafeedbackcontrolloop:

feedbackbecausethe

actual

value

is

fed

back

through

abackward

leadingpathandthencomparedwiththedesiredvalue

loopbecause,obviously,thestructureofthissystemisaloop


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Controlloopanatomy

Almostallcontrolloopshavethislogicalstructure:

Thereare

four

components

(controller,

actuator,

plant,

sensor)

Themeasuredvalue ishopefullyanaccuratereflectionoftheactualvalue.Itiscomparedagainstthedesiredvaluetoproducetheerror.

Ifallisworkingasdesired,c=r,soe =0


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Someotherpoints AsitsbasicgraphicaltoolControlsusesblockdiagrams,asillustrated

Blockdiagrams

have

specific

rules

that

they

follow:

Thereisasingleinputandasingleoutput

Theinputisoperatedonbytheblockcontentsandthenputontheoutput

Ablockmaybemorecomplicatedthanitappears. Itmaynotbejustasimpleblockbutmadeupofanumberofblocks,likethecontrolsystemblockonthethirdslide.

Sincealmostallcontrolloopshavethestandardstructureasgiven,itisveryhelpfultohavethisstructureinmindwhenyouapproachanexistingsystem,tryingtounderstandit:

The

controller

reacts

to

the

error.

If

the

error

is

non

zero,

what

youve

got

is

not

equal

towhatyouwant,sosomethingmustbedone. Thecontrollerrealizesthisandsendsacommandtotheactuatortodosomething.

Theactuatoristhecontrollersagentforaffectingtheplant.

Theplantisthethingcontrolled.

Thesensorsroleistomeasuretheparameteroftheplantthatistobecontrolled.


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Foracruisecontrolinacar


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Regulatorvs.positioner

Thereare

two

types

of

control

loopsa

regulator

and

a

positioner

Aregulatorholdsanoutputconstantdespite

disturbancesthattrytoknockitoffthisvalue

Desiredvaluedoesntchange

Thereexistdisturbances

Apositioneris

afly

by

wire system

Input(desiredvalue)constantlychanges

Jobofcontrolleristotracktheinput(makeoutput

followinput)


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Throttlebywire

AcceleratorPedal

Air

ThrottleValve

Nonmechatronic,mechanicalthrottle

AcceleratorPedal

Air

ThrottleValve

Mechatronic

System

a

t

Mechatronicthrottle


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ThrottlebywireAccelerator

PedalAir

ThrottleValve

MechatronicSystem

a

t

Mechatronicthrottle

Sensor: potentiometeronthrottlevalve

Actuatoris

asmall

DC

motor

on

throttle

valve,

which

controls

air

into

engine

Plantisthrottlevalve,thethingthatscontrolled

Thereisalsoapotentiometerontheacceleratorpedalthatsenseits

angle. Thisisturnedintoadesiredvalueforthethrottlevalve. Itneed

notnecessarilybe1:1.


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Throttlebywire Thisisapositionersystem. Acceleratorpedalpositionisconstantly

changingwith

normal

driving.

Thepedalitselfjustbecomesawaytoexpressawish. Thisistrueofall

flybywiresystems. Inanairplane,theyoke,stick,rudderpedalsarejust

wishexpressingdevicestosettheanglesofcertaincontrolsurfaceson

theairplane.

ToyotaintroducedthrottlebywireintotheAmericanmarketandthere

havebeeninnumerablelawsuitssurroundingitduetoinstancesof

unintendedacceleration. Butnoneofthesehavebeenproventohave

beencausedbythrottlebywire. Rathertheyvebeenattributableto

mistakes,likepushingontheacceleratorpedalwhenitwasdesiredto

pushthe

brake

pedal,

and

like

having

the

accelerator

pedal

get

trapped

underthefloormat.

Whyhavethrottlebywireatall? Allowscomputercontrolofthrottlefor

suchthingsasadaptivecruisecontrolandelectronicstabilityprotection.


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Mechatronicgearshift

ShiftbyWireGangwahlschalter

AlslangjhrigerMechatronikPartnerderAutomobilindustriehatKOSTALnunimBereichderMittelkonsole

mitdemelektronischenAutomatikwahlhebeleineneueHerausforderungerfolgreichbewltigt.

Asyoucansee,thisisagearshifter

withnodirectconnectiontothe

transmission,soitsshiftbywire.

Nowadaysitcandriveeitheran

automatictransmissionoramanual

transmissionwithoutaclutchpedal.

Thusthegearshifthasbecome,again,

justameansofexpressingawish.


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Mechatronicgearshift

Thisshowsashiftingstrategyforshiftingup

ordown. Generallywithupshiftingyou

drivetheengineuptoahigherspeedbefore

shiftingthanyouwouldusetoshiftthe

gearstoalowergearwhenslowing.

Thegearshiftingalgorithmiseventdriven

andisjustaswitching,notacontroller

regulatedloopaspresentedforcruise

controlor***bywire.


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ABSsystem

Theway

an

anti

lock

braking

system works

is

also

on/off. Ifawheelislockedinbrakingbecauseof

lowroadfriction,thisissensedandthebraking

momentonthewheelissimplyreleasedtoletthe

wheelonceagainnotsliponthesurface. Then

thebrakingmomentisappliedagain. Thiscanbe

done

very

quickly.

So

this

is

not

a

control

system

insmoothlymodulatedcontrolasdescribedfora

cruisecontrolsystemoraXbywiresystem.


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andIhaventevenmentioned

enginecontrol

Actuators

CoilInjectorThrottle valve

Camshaft controlExhaust gasrecirculationIntake manifoldswitching

FanGasoline pumpSecondary airExhaust gas valveSupercharger bypassFuel tank vent

EngineControlSystem

Sensors

Accelerator pedalThrottle valve angleCrankshaft angleCamshaft angleIntake air flowInlet air temperatureTurbocharger pressureAmbient air pressureCooling watertemperature-sensor signalExhaust gas

temperatureClutch positionGasoline pressure

Thisisacomplicated,multipleinput,multipleoutputsystem,nota

simplecontrolloopwithasingleinputthedesiredvalueanda

singleoutputtheactualvalue.


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Mechatronicnetworkinvehicle

Allofthesensors,actuators,andmicroprocessorsarenetworkedtogether


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Computercontrolledloops

Thereisnotaseparateprocessorforeachloop,ratherthecontrollers

foreachloopruntogetheronascheduledbasisinthecentral

processingunit,

the

central

computer.

The

control

loop

structure

represents,logically,howthesystemworks. Butallthesensorsand

actuatorsarephysicallylinkedtogetheraswasshownintheprevious

slide.


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Ourfocustoday

We

shall

focus

on

control

loops,

their

structure,andhowtheyareusedtocontrol

systems

Weshallalsoworkonbuildingupyour

experiencewithSimulink

Youshallworkthroughasimulationexercise

usingSimulink,writingareportonthisas

yougo.


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SomelinksNewYorkTimesarticleaboutelectroniccar:

http://www.nytimes.com/2010/02/05/technology/05electronics.html

ClemsonVehicularElectronicsLab:

http://www.cvel.clemson.edu/auto/systems/autosystems.html

Wikipediaondriverassistancesystems:

http://en.wikipedia.org/wiki/Advanced_driver_assistance_systems

Braunschweig PDFondriverassistancesystems:

http://fens.sabanciuniv.edu/icat2006/icat2000

2006/tr/2004/matbaa/papers/9.Ferit%20Kucukay%20%20Driver%20Assistant%20Systems.pdf

Kostalshiftbywire:

http://www.kostal.com/german/2 010105.html


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Somemorelinks http://www.calpoly.edu/~fowen/AutoMech/ElectronicTransmissionControl.doc

http://www.calpoly.edu/~fowen/AutoMech/OttomotorSteuerung.doc

IntroductionToControls-AutomotiveMechatronics

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