Autonomous Landing UAV

8/12/2019 Autonomous Landing UAV

1/58


2/58

Autonomous Landing UAV

Session 2008/2009

I | P a g e

Summary

ThisthesispresentsthesystemarchitectureforlandinganUnmannedAerialVehicle

(UAV)fromahoveringpositionwithouttheinterventionofahumanoperator.

Throughtheuseoffeedbackinformationfromaheightsensor,theUAVis

commandedtoperformcontrolleddescentwiththedesiredlandingparametersby

implementationoftheflightcontrollaws.

Theplantmodelofthesystemwasdeterminedinordertosimulatethesystem

usingMatlab,Simulink.Throughtheuseofsimulations,thevariablesofthe

controllersarevariedtodeterminethemostappropriategainsthatwillresultinthe

mostpreferredlandingprofile.

Inthis

project,

the

vertical

component

which

controls

the

climb

and

descends

of

the

platformwasisolatedfromtheroll,pitchandyawthroughtheuseofajig.Therefore,

thiscurrentprojectonlycommandstheheightoftheplatformbutcanbefully

expandedtocommandtheroll,pitchandyawwithadditionsensorssuchasrate

gyro.


3/58


Session 2008/2009

II | P a g e

Acknowledgement

Theauthorwouldliketoexpresshisappreciationtotheprojectsupervisor,

AssociateProfessorGerardLengSiewBing,fortheopportunitytoworkonthis

project,aswellasforhispatientguidanceinthevariousaspectsoftheproject.

Theauthorwouldalsoliketoextendhissincereappreciationtothefollowingpeople

fortheirassistanceduringthecourseofthisproject:

1. MrMuhamadAzfarbinRamli,GraduatestudentoftheCOSYlab,forhiskindassistancetothevariousproblemsthatwasencounteredduringthecourse

ofthisproject.

2. MsAmyChee,MsPriscillaLee,MrChengKokSengandMrAhmadBinKasa,StaffoftheDynamics&Vibrationlab,fortheirhelpandsupportwith

necessary

equipments.

3. MrRonaldTanHanRongforhissupportandassistanceduringtheconstructionphaseofthecoandereffectflyingsaucer.


4/58


Session 2008/2009

III | P a g e

ContentsSummary .................................................................................................................................... I

Acknowledgement .................................................................................................................... II

ListofFigures ............................................................................................................................V

ListofTables ............................................................................................................................ VI

ListofSymbols ........................................................................................................................ VII

1. Introduction...................................................................................................................... 1

1.1. Objective ................................................................................................................... 1

1.2. Historicalbackground ............................................................................................... 1

2.Theory............................................................................................................................... 3

2.1. HelicopterAerodynamics.......................................................................................... 3

2.2. PIDSystem ................................................................................................................ 4

3. HardwareandSetup........................................................................................................ 5

3.1. UAVPlatform ............................................................................................................ 5

3.1.1. CoanderEffectFlyingsaucer............................................................................. 5

3.1.2. DraganflyerTiV................................................................................................. 6

3.2. Testbedconstruction ............................................................................................... 7

3.3. Sensorwithmounting............................................................................................... 8

3.4. Microcontroller:BasicStamp.................................................................................... 8

3.5. Communication......................................................................................................... 9

3.6. Problemsencountered ........................................................................................... 10

3.6.1. Pausewidth..................................................................................................... 10

3.6.2. Trimmedsignal................................................................................................ 10

3.6.3. LagtimebetweenPulseTrain......................................................................... 10

3.7.

Programmingalgorithm.......................................................................................... 13

4. Experimentsconducted................................................................................................. 14

4.1. OperationoftheFutabaRFtransmitter ................................................................. 14

4.2. ExperimentsonDraganflyer ................................................................................... 15

5. ResultsandDiscussions.................................................................................................. 18


5/58


Session 2008/2009

IV | P a g e

5.1. Testingandcalibrationofultrasonicsensor ........................................................... 18

5.2. Determinerelationshipbetweenthrottleandthrust............................................. 19

5.3. MeasurementofPWMsignalfromradiotransmitter............................................ 19

5.4.

Relationshipbetween

helicopter

controls

and

pulse

width ................................... 21

5.5. Determinesystemplantmodel .............................................................................. 22

5.6. SimulationsusingMatlab,Simulink ........................................................................ 23

5.6.1. ZieglerNicholsmethod ................................................................................... 23

5.6.2. ProportionalDerivativecontrol:TrialandErrormethod ............................... 23

5.7. Flighttest ................................................................................................................ 24

5.7.1. Flight1:Scheduledproportionalcontrol ........................................................ 24

5.7.2. Flight2:Throttlereductionof20% ................................................................. 25

5.7.3. Flight3:ProportionalDerivativecontrol ........................................................ 25

5.7.4. Flight4:Hovertosetpoint ............................................................................. 26

5.8. Analysiswithsimulatedplot ................................................................................... 27

5.8.1. Comparingsimulationandactualplot............................................................ 27

5.8.2. Rootlocusanalysis.......................................................................................... 27

6. Conclusions..................................................................................................................... 30

7. RecommendationsforFurtherWork............................................................................ 31

7.1.

Integratingcontroller

for

Roll,

Pitch

and

Yaw......................................................... 31

7.2. Camerasystemtolocatelandingzone ................................................................... 31

References .............................................................................................................................. 32

AppendixI. FiguresandTables ...................................................................................... 34

AppendixII. Fourworkingstatesofarotorinaxialflight ............................................. 37

AppendixIII. Coandereffect ............................................................................................ 39

AppendixIV. ZieglerNicholstuningmethod................................................................... 40

AppendixV. CoanderEffectflyingsaucerexperiment .................................................. 41

AppendixVI. Autonomouslandingprogram(Basic) ....................................................... 45


6/58


Session 2008/2009

V | P a g e

ListofFigures

Figure1:(A)WakebehaviourOGE/IGE;(B)ThrustratioVsDistance ..........................3

Figure2:

Block

Diagram

of

PID

Control

system ............................................................ 4

Figure3:ConstructionoftheCoanderEffectUAV ....................................................... 5

Figure4:FlightcontroloperationoftheDraganflyerVTi............................................6

Figure5:ConstructedTestbed.....................................................................................8

Figure6:UltrasonicdistancesensorattachedtoUAV .................................................8

Figure7:Communicationofcontrolsystem.................................................................9

Figure8:Lagtimebetweenpulsetrain ......................................................................11

Figure9:

New

communication

system........................................................................12

Figure10:Flowchartofautonomouslandingsystem................................................13

Figure11:ExperimentalsetuptomeasurePWMsignal.............................................14

Figure12:Experimentalsetuptomeasuregeneratedthrust ....................................15

Figure13:SystemplantmodelledinSimulink............................................................16

Figure14:(A)Ultrasonicsensorresults;(B)Percentageerrorbelow40cm ..............18

Figure15:PlotofThrustVsThrottle...........................................................................19

Figure16:

PWM

Signals

from

Futaba

transmitter ...................................................... 19

Figure17:Sevenchannelsfromsinglepulsetrain .....................................................21

Figure18:(a)PlotofThrottleVsPulsewidth;(b)PlotofThrustVsPulsewidth ....... 21

Figure19:PlotsofRateofdescentVsPulsout ...........................................................22

Figure20:Systemsplantmodel.................................................................................23

Figure21:SimulationsusingZieglerNicholsmethod.................................................23

Figure22:SimulationsusingPDcontrol ..................................................................... 24

Figure23:

Results

using

scheduled

proportional

control ........................................... 24

Figure24:Resultsusingthrottlereductionmethod...................................................25

Figure25:ResultsusingPDcontrol:(a)Kp:1.0/Kd:1.0;(b)Kp:3.0/Kd:1.0..................25

Figure26:HoveringtosetpointusingPDcontrol......................................................26


7/58


Session 2008/2009

VI | P a g e

Figure27:Comparisonbetweensimulatedandactualplot.......................................27

Figure28:Rootlocusplot ........................................................................................... 28

Figure29:ModelofCoandereffectUAVusingSolidworks........................................34

Figure30:

Test

bed

model

in

Solidworks .................................................................... 34

Figure31:PinOutdiagramofRFtransmitter,FutabaSkysport6T6YG ..................... 35

Figure32:Modifiedwiringintotrainerport...............................................................35

Figure33:Futabatransmittercontrolsdiagram.........................................................35

Figure34:Serialcommunicationwithflowcontrol....................................................36

Figure35:DescriptionofPulsewidthVsChannel ...................................................... 36

Figure36:FlowvisualizationatvariousdescentvelocitiesusingShadowgraphy......37

Figure37:Flowacrossalimitingsurface.................................................................... 39

Figure38:ModificationtoPlatform ...........................................................................41

Figure39:J.Naudinsexperimentalsetup..................................................................42

Figure40:Naudinsresult ........................................................................................... 42

Figure41:Experimentalsetupforairspeedmeasurement........................................43

Figure42:Variablesofexperiment.............................................................................43

ListofTables

Table1:ZieglerNicholstuningchart ..........................................................................40

Table

2:

Airspeed

test

results......................................................................................44


8/58


Session 2008/2009

VII | P a g e

ListofSymbols

h Altitude,displacementfromgroundAltituderatechange

e Error

or Proportionalgain

Integralgain

Derivativegain

Integralcontrollerscaler

Derivativecontrollerscaler

Ultimateperiod

Controllertransferfunction

Open

loop

transfer

function

Closedlooptransferfunction

Risetime

Peaktime

Settlingtime

Maximumovershoot


9/58

Introduction

Session 2008/2009

1 | P a g e

1. Introduction1.1.Objective

ThisprojectaimstodevelopanautonomouslandingsystemthatwillenableaUAV

tolandautonomouslywithouttheinterferenceofahumanoperator.Thescopeof

thisprojectwaslimitedtothealtitudecontrolonly,withouttheinterventionofthe

Roll,PitchandYawmotion.However,thedevelopedconceptsandcontrollawscan

alsobefurtherextendedtoencompassRoll,PitchandYawcontrolwithadditional

sensorssuch

as

the

rate

gyro

or

the

tilt

sensor.

Someotherobjectivesaretheselectionandtestingofasuitablealtitudesensor,the

implementationoftheflightcontrollawsusingtheProportionalIntegralDerivative

(PID)controller,thetuningofthePIDgainsusingvariousmethodsandlastlyaflight

demonstrationtovalidatetheautonomouslandingsystem.

1.2.HistoricalbackgroundTheconceptofUAVbeganduringtheAmericanCivilWar,whentheNorthandthe

Southattemptedtobombeachothersammunitiondepotbylaunchingballoons

carryingexplosivedevicewhichwouldbereleasedatacontrolledtiming.However,

theactualbeginningstartedduringWorldWarII,whenacompanyChanceVought

Aircrafthadproposedbuildingmissileswithlandinggear,inordertosavecost.


10/58

Introduction

Session 2008/2009

2 | P a g e

Recently,UAVsuchastheGlobalHawkandthePredator,haveachieved

considerablepopularity,whenitwasemployedtoprovideaerialsurveillanceaswell

asattack

missions

in

Afghanistan.

There

are

many

other

useful

applications

of

UAV

suchashomelandsecurity,cropdustingandtrafficmonitoring.

UAVcanbeclassifiedundertwodistinctcategories,FixedwingandRotary.Some

examplesofRotaryUAVincludehelicopter,MicroAirVehicleandOrganicAir

Vehicle,whereastheGlobalHawkandPredatorrepresentsFixedwingaircraft.

AccordingtoReinHardt[2],thenextgenerationofUAVswillbesmallerinsize,more

affordable,easiertotrainandmoreprecisethantheexistingUAVs.Also,UAVsare

expectedtobecapableofdetectingnuclear,biological&chemicalweapons,looking

intodoublecanopyjunglesandprovidelowcost,reliablecommunicationsanddata

relayacrossthebattlefield.Inurbanbuiltupareas,whereairspaceisoftenlimited,

VerticalTakeOffandLanding(VTOL)UAVisoftenemployed.

TheremotepilotingofaVTOLUAVisaverychallengingtaskwhichrequiresgreat

operatorskillandattention[4].Furthermore,mostmaneuverswouldrequirethe

pilottomaintainfullvisualcontactwiththeUAVatalltimes,especiallyduringthe

landingphase.Inaddition,someotherfactorsthatmightaffecttheRemotecontrol

(RC)performancearepoorpositionalaccuracy,pooraltitudeaccuracyandpilot

fatigue[4].


11/58

Theory

Session 2008/2009

3 | P a g e

2. Theory2.1.HelicopterAerodynamics

ThefourworkingstatesofarotorinaxialflightaredescribedinAppendixII.In

particular,thevortexringstateshouldbeavoidedduringdescentasitmightresult

inhighlyunsteadyflowwithnonlinearityasaffirmedbyYaggy&Mort(1963).This

unsteadinesscancausesignificantbladeflapping,uncommandeddropindescent

rate,lossofcontroleffectiveness,andexcessivethrustfluctuations.

Figure1:(A)WakebehaviourOGE/IGE;(B)ThrustratioVsDistance

Groundeffectcanalsoaffecttheperformanceofahelicopter.Figure1Ashowsthe

wakebehaviorfromahoveringstateInandOutofgroundeffectandfigure1B

showstheincreaseinthrustratioatdifferenthoveringheightastestedby

Fradenburgh(1972)andHayden(1976).Theseresultssuggestsignificanteffectson

hoveringperformanceforheightsoflessthanonerotordiameter,wherethereisa

sharpincreaseinthrust.


12/58

Theory

Session 2008/2009

4 | P a g e

2.2.PIDSystem

Figure2:BlockDiagramofPIDControlsystem

TheclassicalcontroltheorywithaclosedloopPIDcontrollerisusedtocontrolthe

altitudeoftheUAVasillustratedbytheblockdiagraminfigure2.Theultrasonic

sensorattached

to

the

UAV

provides

range

feedback

for

the

closed

loop

system

and

itsdataisalsocapturedbythecomputerfordataloggingpurposes.Severalmethods

oftuningthegainsofthecontrollerareproposed.


13/58

Hardware and Setup

Session 2008/2009

5 | P a g e

3. HardwareandSetup3.1.UAVPlatform

Forthisproject,arotarytypeplatformwasselectedasitisabletomaintaina

hoveringpositionbeforethelandingcommandisinitiated.Duringtheinitialstage,a

hovercraftwhichusescoandereffecttoproduceliftwasexplored.However,dueto

thenatureofthisproject,aswellastheproblemsencountered,itwaseventually

replacedwithanotherofftheshelfplatform,thedraganflyerVTi.

3.1.1. CoanderEffectFlyingsaucerThephenomenonwhichcausesflownearlimitingsurfacetofollowthegeometrical

shapeofthesesurfacesisknownastheCoandereffect.Accordingtoresearcher

JeanLouisNaudin,theVTOLplatformwasabletoattaingoodcontrol,stabilityand

thrustwhichiscomparableorevenbetterthanaconventionalRChelicopter.In

accordancewith

his

built

plan,

asimilar

platform

was

modelled

using

CAD

software,

SolidworksinAppendixI,figure29,andbuiltcarefullyasshowninfigure3.

Figure3:ConstructionoftheCoanderEffectUAV


14/58

Hardware and Setup

Session 2008/2009

6 | P a g e

However,subsequenttestsconductedontheplatformconcludedthatthecoander

effectwasunabletoproducesufficientliftaspromised.Detailedexperimentsthat

wereconducted

to

verify

the

lift,

as

well

as

some

minor

modifications

to

the

UAV

areattachedtoAppendixVforreference.

3.1.2. DraganflyerTiVTheflightcontrolsoftheDraganflyeroperatesolelyondifferentialthrustbetween

thefrontrearandleftrightmotor,wherebyanetresultantmomentcanbe

generatedalong

the

roll

axis

(x

axis)

or

the

pitch

axis

(y

axis)

to

produce

aroll

or

a

pitchmotionasshowninfigure4.

Figure4:FlightcontroloperationoftheDraganflyerVTi

Forinstance,topitchtheUAVup,thefrontmotorwillrotatefasterthantherear

motor.Anotheradvantageofthisplatformisthatnomechanicallinkageisrequired

asthereisnocontrolsurface.


15/58

Hardware and Setup

Session 2008/2009

7 | P a g e

3.2.TestbedconstructionInordertoinvestigateandtunetheentireUAVsystem,differentjigswithdifferent

degreeof

freedom

(DOF)

are

required.

For

example,

in

order

to

tune

the

PID

controllerfortherollmotion,atestbedwhichrestrictstheUAVmotiontotheroll

axisonlyisrequired.Generally,thePIDcontrollermustbetunedseparatelyforthe

individualroll,pitchandyawaxis[11].

Forthisproject,thePIDcontrollerthatmustbetunedisinthetranslationalz

direction,withreferencetofigure4.Therefore,atestbedwith1DOFinthe

translationalzdirectionisrequired.Thetestbeddesignismodelledusing

SolidworksasshowninAppendixI,figure30.Thedimensionoftheceilingframeis

modelledaccordingtotheactualdimensioninthelaboratory.TheUAVismounted

onacarbonfibrecrossbar,andthecrossbarisjoinedtotheverticalpolystyrene

supportsby

four

prismatic

joints,

which

allows

translational

displacement

along

the

verticalsupportsonly.Therefore,thissetupcaneffectivelyconstraintheUAVtothe

translationalzdirectionasshowninfigure5.


16/58

Hardware and Setup

Session 2008/2009

8 | P a g e

Figure5:ConstructedTestbed

3.3.SensorwithmountingThePING)))Ultrasonicrangesensorisattachedtoamountingmadeofbalsawood

andhighdensityfoamisusedtoprotectthesensorfromimpactwiththeground.

Figure6:UltrasonicdistancesensorattachedtoUAV

3.4.Microcontroller:BasicStamp


17/58

Hardware and Setup

Session 2008/2009

9 | P a g e

ThemicrocontrollerBasicstampBS2pxandBS2pefromparallaxwasusedtoprocess

theinformationfromtheultrasonicsensorandtogeneratetherequiredsignal.

3.5.Communication

Figure7:Communicationofcontrolsystem

Figure7illustratestheoriginalcommunicationsofthelandingsystem.Tosimplify

theproblem,theconnectionbetweentheultrasonicsensorandthemicrocontroller

wasphysicallywired.Initially,asinglemicrocontrollerBasicstampBS2pxwasused

tocalculate

the

distance

from

the

range

sensor

as

well

as

processing

the

data

and

generatingthenecessarysignaltotheRadiofrequency(RF)transmitter.The

transmitterwillthenrelaythesignalstotheUAVviathetrainerport.

APinOutdiagramoftheFutabatransmitterisshowninAppendixI,figure31.In

ordertocontroltheUAVusingthemicrocontroller,thesixpinplugismodifiedand

only

three

of

the

pins

are

used:

Pin

2

(PPM

Out),

Pin

3

(PPM

In)

and

Pin

7

(Ground

shield).Pin2isusedtomonitorthesignalsgeneratedbythetransmitterandPin3is

usedtoreceivethesignalsfromthemicrocontrollerintothetransmitter.TheRadio

FrequencysignalisfinallytransmittedtothereceiveronboardtheUAV.


18/58

Hardware and Setup

Session 2008/2009

10 | P a g e

3.6.Problemsencountered3.6.1. Pausewidth

Forbasic

stamp

microcontroller,

the

command

PAUSE

will

cause

adelay

where

no

signalwillbetransmittedtothepin.However,thesmallestunitis1millisecond

whereasthepauserequiredbetweenchannelsisonly0.4ms.Toovercomethis

problem,anotherpulsesignalwassenttoanotherdummypin,whichwillresultin

aninduceddelaytotheactualpinthatisconnectedtothetransmitter.

3.6.2. TrimmedsignalItwasobservedthatthetrimmingsonthetransmitteraffectthesignalsthatare

generatedquitesignificantly.AppendixI,figure33showstheFutabatransmitter

withthetrimcontrol.Thus,theUAVattachedtothetestbedshouldbeproperly

trimmedtomaintainhoverbeforethegeneratedsignalsaremeasured.

3.6.3. LagtimebetweenPulseTrain


19/58

Hardware and Setup

Session 2008/2009

11 | P a g e

Figure8:Lagtimebetweenpulsetrain

Figure8ashowsthelagtimeof98msforthefulllandingprogramand8bshowsthe

reducedoroptimizedprogram,havingalagtimeof56ms.However,itisstillfar

fromthedelayrequiredof0.4ms.

Tosolvethisproblem,analternativecommunicationsystemisrequired.Figure9

showsthenewcommunicationsystemthatrequirestwomicrocontrollersto

operatesimultaneously.BS2pewasusedtocollectfeedbackdatafromthe

ultrasonic

sensor

and

acts

as

the

PID

controller

to

processes

the

retrieved

data.

It

is

alsoconnectedtothecomputerwhichwillsavetheinformationfordatalogging

purposes.AnothermicrocontrollerBS2pxwasconnectedtoBS2pethroughserial

communication.TheprimaryfunctionofBS2pxistogenerateregularpulsesof

signalstotheRFtransmitter.Thisisverycrucialaslonglagtimewillregisterasa

temporarylossoflinkwhichwillcausetheUAVtobecomeuncontrollableand

twitchesviolently.Therefore,thefasteststampBS2pxwithprocessingspeedofup

to19,000instructionspersecondwasemployedtoperformthisduty.


20/58

Hardware and Setup

Session 2008/2009

12 | P a g e

Figure9:Newcommunicationsystem

Uponfurtherinvestigation,itwasdeducedthattheultrasonicsensor,runningat

about20Hz,iscausingthelonglagtime.Thus,theusageoftwobasicstampscan

effectivelyisolatetheinherentlagtimeproblemthatiscausedbythesensor.

AppendixI,figure34showstheconnectionsbetweenthetwostampswithflow

control.OneofthelimitationsofStampisthatwhenitissendingorreceivingdata,

itcannot

execute

other

instruction

and

vice

versa.

The

Stamp

does

not

have

aserial

bufferwhichispresentinothercomputers.Also,evenwhenrunningatthehighest

serialbaudrates,thereisinsufficienttimefortheStamptoreceivedata,processit

andexecuteanotherreceivingdatacommandintimetocatchthenextstreamof

data,unlesstherearesignificantpausesbetweendatatransmissions.Fortunately,

flow

control

can

be

used

to

overcome

this

problem

whereby

the

receiver

can

tell

the

senderwhenitisreadytoreceivethenextstreamofdata.Also,stampcanonly

transmitasinglebyteatatime.Therefore,thesignalthatwillbesentwasscaled

downby10inordertostaywithinthesinglebytelimitofvaluesbetween0255.


21/58

Hardware and Setup

Session 2008/2009

13 | P a g e

3.7.Programmingalgorithm

Figure10:Flowchartofautonomouslandingsystem

Theflowchartabovesummarizestheprogrammingalgorithmfortheentire

autonomouslandingsystem.Atimeoutfunctionisprovidedtoaccountforcases

wherelag

time

exceeds

0.8ms.

In

such

cases,

this

function

will

generate

asimilar

pulsetrainastheonebefore.Thisistoensurethatthereisaregulargenerationof

pulsesignaltopreventlossoflink.

Anotherconditionthatisusedinthisalgorithmistocheckwhetherthecalculated

distanceislessthan20cm.Ifitistrue,thethrottlewhichcorrespondstolandingis

initiatedinstead

of

the

PID

controller

output.


22/58

Experiment

Session 2008/2009

14 | P a g e

4. Experimentsconducted4.1. OperationoftheFutabaRFtransmitter

Figure11:ExperimentalsetuptomeasurePWMsignal

Experiment1:MeasurementofPWMsignalfromradiotransmitter

ThesignalsgeneratedbythetransmitterarePulseWidthModulation(PWM)signals.

ThisexperimentinvolvesthemeasurementofthePWMsignalgeneratedbythe

FutabaRFtransmitter,atdifferentsticksettings.Theequipmentthatwasusedin

thisexperimentisshowninfigure11.UsingaprobetotapthesignalfromPin2at

thetrainerport,therespectivepulsewidthatdifferentstickpositionscanbe

measuredusingadigitaloscilloscope(TectronixTDS3012).


23/58

Experiment

Session 2008/2009

15 | P a g e

4.2. ExperimentsonDraganflyer

Figure12:

Experimental

setup

to

measure

generated

thrust

Experiment2:DeterminerelationshipbetweenThrottleandThrust

Asimpleexperimentwassetuptoestimatethegeneratedthrustatdifferent

throttlesettingasshowninfigure12.TheUAVwasattachedtoaweightandthe

platformwasplacedontoadigitalweighingscale.Theresultantthrustcanbe

measuredbytheweighingscaleatdifferentthrottlepositions.Twodifferentsetups

aredesignedtomeasurethethrustgeneratedattwodifferentaltitudes.Thisisdone

toestimatethethrustgeneratedIGEandOGE.Theassumptionisthattheattached

weightandweighingscaledonotinterferewiththethrustgeneratedbytherotors.

Experiment3:Testingandcalibrationofultrasonarsensor

TheParallaxPING)))ultrasonicsensorisusedtomeasurethealtitudeoftheUAV.It

ischosenprimarilybecauseofitsavailabilityinthelaboratoryaswellasthesuitable

rangeof2cmto3mwhichsatisfytherequirementofthisproject. Also,itisfully


24/58

Experiment

Session 2008/2009

16 | P a g e

compatiblewiththemicrocontrollerBasicStamp.Inthisexperiment,theultrasonic

sensoristestedandcalibratedwiththeactualdistance.

Experiment4:Determinesystemplantmodel

Theaimofthisexperimentistodeterminetheplantmodelofthesystem.Froma

hoveringaltitudeof100cm,thethrottlewassteppeddownandtheheightvariation

datawasloggeddownusingthesoftwareStampPlotPro.Fromtheserawdata,the

rateofdescent(R.D)canbedetermined.Themagnitudeofthestepswasvariedand

thecorresponding

R.D

was

analysed

to

determine

the

systems

plant

model.

Experiment5:SimulationsusingMatlab,Simulink

Usingthederivedsystemplantmodel,thesystemwasmodelledusingMatlab,

Simulinkasshowninfigure13.

Figure13:SystemplantmodelledinSimulink

Simulationsarecarriedouttoexaminethetheoreticaloutputresponseofthe

systemgiven

astep

down

input.

The

gains

for

the

PID

controller

are

varied

to

determinethesystemresponse.ThetwomethodsoftuningthePIDcontroller,the

ZieglerNicholsmethodandtheTrialanderrormethod,wassimulated.


25/58

Experiment

Session 2008/2009

17 | P a g e

Experiment6:Flighttest

Flight1:ScheduledProportionalcontrol

Twodifferent

values

of

proportional

gains

are

used

depending

on

the

height

of

the

UAV.Forheightofabove45cm,againof2.0isusedandforheightbelowthat,a

gainof1.0isused.Thisistoensurethattherateofdescentisreducedasit

approachestheground.

Flight2:Throttlereductionby20%

Thehovering

throttle

of

the

UAV

was

reduced

by

20%

and

the

rate

of

descent

of

the

UAVwasinvestigated.

Flight3:ProportionalDerivativecontrol

ItwasdeterminedthataPDcontrollerissufficientastheintegraltermwhichwill

compensateforsteadystateerrorisnotrequiredinthisautonomouslanding

system.The

appropriate

proportional

and

derivative

gains

that

are

obtained

from

thesimulationsusingSimulinkareusedinthisexperiment.Also,theactualsystem

responsecanbecomparedwiththesimulatedresponse.

Flight4:Hoveraboutsetpoint

UsingsimilarPDcontroller,UAVwascommandedtohoveratadesiredsetpoint.


26/58

Results and Discussions

Session 2008/2009

18 | P a g e

5. ResultsandDiscussions5.1. Testingandcalibrationofultrasonicsensor

Figure14:

(A)

Ultrasonic

sensor

results;

(B)

Percentage

error

below

40cm

ItwasobservedthatnocalibrationoftheultrasonicsensorisrequirediftheStamp

usedtoreceivethesensordataisBS2pe.However,calibrationisrequiredifthe

StampusedisBS2px.Referringtofigure14A,themeasuredistance(Blue)isfound

tobedeviatedfromtheactualdistance(Green).Sincethedeviationislinear,a

correctionfactorof0.408wasdeterminedempirically.Thecorrecteddistanceis

depictedbytheredline.Itwasalsoobservedthatthepercentageerrorincreases

significantlywhenthesensorwasbelow40cm.Subsequently,anothercorrection

factorof0.440wasdeterminedthesamewayfordistancebelowtherangeof40cm.

Thedifferenceinpercentageerrorplotisshowninfigure14B.


27/58


Session 2008/2009

19 | P a g e

5.2. Determinerelationshipbetweenthrottleandthrust

Figure15:PlotofThrustVsThrottle

Figure15showstherelationshipbetweenthethrottlestickpositionandthe

resultantthrustproducedbythefourrotors.Withthisestimation,theapproximate

throttlepositionthatisrequiredtodescendtheUAVofvaryingweightscanbe

calculatedaccordingly.

5.3. MeasurementofPWMsignalfromradiotransmitter

Figure16:PWMSignalsfromFutabatransmitter


28/58


Session 2008/2009

20 | P a g e

Figure16showsthePWMpulsetrainthatwascapturedbytheoscilloscope.Itwas

observedthatthetimespanforasinglepulsetrainis20msregardlessofthestick

configurationsand

there

are

atotal

of

seven

channels.

Also,

the

pause

width

betweendifferentpulsesis0.4ms.However,thesynchronizationpulsevariesfrom

8.11msto8.83ms,dependingonthedifferentstickcombination.Thisisamore

accuraterepresentationofthesynchronizationpulseascomparedtotheconstant

valueof9msthatwasproposedbyKarWei[14].Theactualsynchronizationpulse

canbecalculatedasfollows:

Figure17showsthesevenpulsesthatarepresentinasinglepulsetrain.Eachof

thesepulsescorrespondstoachannelandtherefore,thereareatotalof7channels.

Channel1controlsaileron,channel2controlselevator,channel3controlsthrottle,

channel4controlsrudder,channel5controlsthermalintelligenceandlastly

channels6and7controlsthelandinggearswitchandflapknobwhicharenotused

inthisUAV.Also,therangeofpulsewidthforthethrottlecontrolismeasuredtobe

from0.74msto1.4ms.


29/58


Session 2008/2009

21 | P a g e

Figure17:Sevenchannelsfromsinglepulsetrain

5.4. Relationshipbetweenhelicoptercontrolsandpulsewidth

Figure18:(a)PlotofThrottleVsPulsewidth;(b)PlotofThrustVsPulsewidth

Sincethisprojectinvolvesthemanipulationofthethrottlecontrol,thedifferent

throttlepositionswhichcorrespondtothepulsewidthofchannel3isexaminedin

detail.TheresultofPercentagethrottleagainstPulsewidthisshowninfigure18a.

Usinginformationfromsection5.2,theplotofThrustagainstPulsewidthis

obtainedandplottedinfigure18b.Fromthisresult,therequiredthrustcanbe

generatedwiththecorrectpulsewidth.


30/58


Session 2008/2009

22 | P a g e

Therestofthepulsewidthsfromotherchannelsthatcorrespondstothe2extremes

ofthestickpositionareplottedinAppendixI,figure35.Forinstance,fullaileron

rightcorresponds

to

aminimum

pulse

width

of

0.78

ms

and

full

aileron

left

correspondstoamaximumpulsewidthof1.42ms.

5.5. Determinesystemplantmodel

Figure19:PlotsofRateofdescentVsPulsout

Thedescentratesatdifferentstepthrottledowninshowninfigure19ac.Atotalof

threetrialsareconductedandresultsareplottedinfigure19d.Thesystemsplant

modelcanbederivedfromthegradientofthelinewhichisabout1.7.

Therelevantequationstoderivetheplantmodelareshownbelow:


31/58


Session 2008/2009

23 | P a g e

where canberepresentedby and represente ydb

Laplacetransform

SinceKis1.7, theplantmodelcanberepresentedbytheblockdiagrambelow.

Figure20:Systemsplantmodel

5.6. SimulationsusingMatlab,Simulink5.6.1. ZieglerNicholsmethod

Figure21:SimulationsusingZieglerNicholsmethod

ThesimulatedresultsusingtheZieglerNicholsmethodisshowninfigure21.Both

resultsshowshighovershootwithcomparativelylongsettlingtime.

5.6.2. ProportionalDerivativecontrol:TrialandErrormethod


32/58


Session 2008/2009

24 | P a g e

ThesimulationresultsusingthePDcontrollerisshowninfigure22.Thesettlingtime

ismuchmoreacceptablecomparedtothepreviousmethod.Thus,thismethodwill

beused

in

the

actual

flight

test.

Figure22:SimulationsusingPDcontrol

5.7. Flighttest5.7.1. Flight1:Scheduledproportionalcontrol

Figure23:Resultsusingscheduledproportionalcontrol

Figure23showstheactualflightresultsusingscheduledproportionalcontrol

methodasdescribedearlier.Theresultisgoodwithfastsettlingtimeofabout1.7s

andcontrolledsmoothlanding.


33/58


Session 2008/2009

25 | P a g e

5.7.2. Flight2:Throttlereductionof20%

Figure24:Resultsusingthrottlereductionmethod

Thelandingusingthrottlereductionof20%showssimilarlysmoothdescent.

However,theUAVhoverstoapointofabout20cmwhereitencountersground

effect.Asaresult,manualcontrolisrequiredtoforceittoland.

5.7.3. Flight3:ProportionalDerivativecontrol

Figure25:ResultsusingPDcontrol:(a)Kp:1.0/Kd:1.0;(b)Kp:3.0/Kd:1.0

ThesamegroundeffectisencounteredusingthePDcontrollerwithproportional

gainof1.0asshowninfigure25a.Forthiscase,theUAVhoveredtoaheightof

about40cmandrefusestodescendanyfurther.Thiscanbeovercomebyincreasing


34/58


Session 2008/2009

26 | P a g e

theproportionalgainto3.0infigure25bwherethelandingissmoothwithquick

settlingtimeofabout1.3s.

5.7.4. Flight4:Hovertosetpoint

Figure26:HoveringtosetpointusingPDcontrol

UsingthesamePDcontrollerwithproportionalgainof3.0andderivativegainof1.0,

theUAViscommandedtoadesiredheightasshowninfigure26.Thecommandwas

initiatedataheightof35cmanditrisesquicklytothedesiredaltitudeafter1

oscillation.

Thetransientperformanceiscalculatedasfollows:

Risetime: (From0%to100%)

Peaktime:


35/58


Session 2008/2009

27 | P a g e

Settlingtime: (Timetoreachandstaywithin5%limit)

Maximum%overshoot:

Thissystemcanbefurthertunedtoreduceovershootbyloweringtheproportional

gainandreducingthesteadystateerrorbyincludinganintegraltermintothe

controller.However,thesteadystateerrorisreasonableasitiswithinthe5%limit.

5.8. Analysiswithsimulatedplot5.8.1. Comparingsimulationandactualplot

Figure27:Comparisonbetweensimulatedandactualplot

Thesimulatedandactuallandingprofileisplottedforcomparisoninfigure27.The

redlineshowsthesimulatedplotusingMatlabandtherestoftheplotscorrespond

totheactualtestflightdata.Itcanbeconcludedthattheactualplotsfitthe

simulatedplot

reasonably

well.

5.8.2. RootlocusanalysisReferringtofigure13,thetransferfunctionofthesystemisderivedas:


36/58


Session 2008/2009

28 | P a g e

Assumingunityfeedback:

ProportionalDerivativeControl:

OpenLooptransferfunction:

ClosedLooptransferfunction:

TakingKp=3,Kd=1,K=1.7,

ClosedLooptransferfunction:

Theopenlooptransferfunctioncanalsobewrittenintheform:

wherezandparethezeroandpoleoftheopenlooptransferfunction.Asthegain

changes,thevaluesofthecloselooppoleswillchangeandthusthetransient

responseand

stability.

The

root

locus

plot

is

aplot

of

the

loci

of

the

close

loop

poles

onthesplaneasthegainKvariesfrom0toinfinity.

Figure28:Rootlocusplot


37/58


38/58

Conclusion

Session 2008/2009

30 | P a g e

6. ConclusionsThisthesishaspresentedacompletesystemtocontroltheheightofaUAVusing

feedbackcontrol

from

an

ultrasonic

sensor.

The

method

of

communication

between

thedifferentmicrocontrollersandtransmitterwerediscussedaswellassomeofthe

problemsthatareassociatedwiththecommunications.Differentmethodsoftuning

thePIDcontrolsystemwereexploredwiththeaidofsimulationsusingMatlab,

Simulink.Finally,actualtestflightsarecarriedouttovalidatetheautonomous

landingsystem.

All

the

objectives

of

this

project

were

well

met.


39/58

Recommendation

Session 2008/2009

31 | P a g e

7. RecommendationsforFurtherWork7.1. IntegratingcontrollerforRoll,PitchandYawInthisproject,aheightsensorisusedtoprovidefeedbackforthePIDcontrollerfor

altitudecontrol.However,thiscanbefurtherextendedtotheroll,pitchandyaw

motion.Inordertodoso,additionalsensorsarerequiredtoprovidefeedback

informationabouttheUAVsorientationorangularvelocity.Tiltsensorsorrategyro

canbeusedinsuchcasestoprovidecompensationfortheroll,pitchandyaw

motion.In

the

thesis

by

KarWei

[14],

he

had

successfully

used

atilt

sensor

to

compensatefortherollandpitchmoment.

Anotheralternativemethodistoextracttherawdatadirectlyfromthethreepiezo

electricgyrothatarealreadypresentonthecircuitboardDraganflyerVTi.However,

thiswouldrequireknowledgeaboutthecircuitboardtopreventdamageonanyof

thecomponentsonit.

7.2. CamerasystemtolocatelandingzoneAcamerasystemcanbeintegratedintotheUAVtolocatethelandingzonefrom

anotherposition.InthethesisbyZhikang[17],hehadusedcolorsegmentationto

segmentacoloredlandingzoneandapanandtiltcameratotrackontothetarget.

Finally,thepositionoftheUAVwascorrectedtothelandingzoneandsubsequently

landed.InordertocommunicatebetweenacomputerandaRFtransmitter,an

interfacePCTxbyEndurancewasused.


40/58

References

32 | P a g e

References

[1]HaniphLatchman(2003,January17).BriefhistoryofUAVS.RetrievedMarch10,2009,fromhttp://aln.list.ufl.edu/uav/UAVHstry.htm

[2]ReinHardtJ.R.,JamesJ.E.&FlanaganE.M.(1999).FutureEmploymentofUAVs,JointForceQuarterly.RetrievedMarch10,2009,from

http://www.dtic.mil/doctrine/jel/jfq_pubs/0822b.pdf

[3] JoshuaHintze(2004,April).Autonomouslandingofarotaryunmannedaerialvehicleinanoncooperativeenvironmentusingmachinevision.BrighamYoung

University,DepartmentofElectricalandComputerEngineering

[4]TeinHau,Tan(2008,May).AutopilotUnmannedAerialVehicle.NationalUniversityofSingapore,DepartmentofMechanicalEngineering

[5] J.Gordon(2006).PrinciplesofHelicopterAerodynamics.CambridgeUniversityPress.

[6]A.R.S.Bramwell,G.Done&D.Balmford(2000).BramwellsHelicopterDynamics.ElsevierLtd.

[7]TomasB.Co(2004,February13).ZieglerNicholsMethod.MichiganTechnologicalUniversity.RetrievedMarch11,2009,from

http://www.chem.mtu.edu/~tbco/cm416/zn.html

[8] J.L.Naudin(2007,February25).TheGFSUAVproject,ACoandereffectflyingsaucer.RetrievedMarch11,2009,fromhttp://jlnlabs.online.fr/gfsuav/index.htm

[9]ChrisSmith(2009).TheAerodynamicsofaPingpongball.RetrievedMarch11,2009,from

http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/the

aerodynamicsofapingpongball/


41/58

References

33 | P a g e

[10] W.KlausandI.S.Martin(1999,May20).MisinterpretationsofBernoulli'sLaw.UniversityFrankfurt,DepartmentofPhysics.RetrievedMarch11,2009,

fromhttp://user.unifrankfurt.de/~weltner/

[11] WaiWeng,Kong&M.S.b.Zainal(2006).DesignandControlofaQuadRotorFlyingRobotforAerialSurveillance.UniversitiTeknologiMalaysia,Centerfor

ArtificialIntelligenceandRobotic.

[12] J.Martin,J.Williams,K.Gracey,A.Alvarez&S.Lindsay(2005,February).BASICStampSyntaxandReferenceManualVersion2.2.RetrievedMarch11,

2009,fromwww.parallax.com

[13] M.Azfar(2007).AerodynamicsandPropulsionofanIndoorUAV.NationalUniversityofSingapore,DepartmentofMechanicalEngineering

[14] KarWei,Chin(2007).FlightDynamicsandControlforanIndoorUAV.NationalUniversityofSingapore,DepartmentofMechanicalEngineering

[15] MartinHebel(2009).PrimertoUsingStampPlotPro,SelmaWareSolutions.RetrievedMarch11,2009,from

http://www.selmaware.com/stampplot/index.htm

[16] NickSacco(2002).HowtheDraganflyerFlies.RotoryMagazine.RetrievedMarch11,2009,from

http://www.rctoys.com/pdf/draganflyer3_rotorymagazine.pdf

[17] Zhikang,Lin(2008).Camerabasedvisionsystemforunmannedairvehicles(UAVs)operations.NationalUniversityofSingapore,DepartmentofMechanical

Engineering


42/58

Appendix I

34 | P a g e

AppendixI. FiguresandTables

Figure29:ModelofCoandereffectUAVusingSolidworks

Figure30:TestbedmodelinSolidworks


43/58

Appendix I

35 | P a g e

Figure31:PinOutdiagramofRFtransmitter,FutabaSkysport6T6YG

Figure32:Modifiedwiringintotrainerport

Figure33:Futabatransmittercontrolsdiagram


44/58

Appendix I

36 | P a g e

Figure34:Serialcommunicationwithflowcontrol

Figure35:DescriptionofPulsewidthVsChannel


45/58

Appendix II

37 | P a g e

AppendixII. Fourworkingstatesofarotorinaxialflight

Figure36:FlowvisualizationatvariousdescentvelocitiesusingShadowgraphy

Figure36showsthefourworkingstatesofrotorinaxialflightandthedescriptions

ofeachstatearesummarizedbelow:

a) NormalWorkingstate:Thetipvorticesfollowsmoothhelicoidaltrajectories.Theflowishighlyperiodicwith

asmoothslipstreamboundaryfreeofanysignificantdisturbances.Thisstate

encompassesclimb,withthelimitbeingthehoveringstate.

b) VortexRingstate:Forlowrateofdescent,thetipvortexfilamentsareconvectedclosertotheplaneof

therotorbutalsomoveradiallyoutwardawayfromit.Athigherdescentrates,the

tipvorticescomeveryclosetotherotorplaneandconsiderableunsteadiness

becomesapparent.Thiscanbeseenbythecontortionsinthetipvortextrajectories


46/58


47/58

Appendix III

39 | P a g e

AppendixIII.CoandereffectThephenomenonwhichcausesflownearlimitingsurfacetofollowthegeometrical

shapeofthesesurfacesisknownastheCoandereffect.Itonlyoccurswhentheflow

isnotforcedtochangeitsdirectiontooabruptlyinordertopreventtheformation

ofturbulenceandseparation.Theclassicexampleisaflowacrossaflatplanewith

anadjacenthalfcylinderasshowninfigure37below.

Figure37:Flowacrossalimitingsurface

In37a,theflowinitiallyfollowsthesurfaceofthecylinderwhicheventually

separatesatsomepointonthecurvedsurface.Anothersimpleexampleis

demonstratedin

5c,

when

water

is

dripped

down

the

back

of

aspoon,

it

will

tend

to

sticktothesurfaceandgetdeflected.Thisimportantbehaviourholdsforallflows

limitedbysmoothlycurvedsurfaceslikeaerofoils,streamlinedobstaclesandsails.

TheCoandereffectcanbeexplainedbyconsideringtheeffectsofviscosityofafluid.

In37b,duetoviscosity,somelayersoftheadjacentairattheendoftheflatsurface,

depictedby

dots,

are

carried

away

by

the

main

stream

flow.

As

aresult,

aregion

of

lowpressureisformedwhichgiverisetoanetforcewhichwillpulltheflowtowards

thecurvedsurface.


48/58

Appendix IV

40 | P a g e

AppendixIV.ZieglerNicholstuningmethodTable1:ZieglerNicholstuningchart

where Kcistheproportionalgain

Iistheparameterthatscalestheintegralcontroller

Distheparameterthatscalesthederivativecontroller

KUistheultimategain

Kp,KiandKdaretheproportional,integralandderivativegains

ThetuningchartfollowsthePIDequation:

Inordertodeterminetheparameters,thefollowingstepsarecarriedout:

1. Setthecontrollertoproportionalcontrolonly.2. StepincrementthecontrollergainKcandwaitforasteadystateoutputbefore

increasingbyanothersubsequentstep.

3. ThecriticalorultimategainKu,isthevalueofKcthatwillresultsinasustainedperiodicoscillationintheoutput.

4. TheperiodofthisoscillationisknownastheultimateperiodPu.5. TherespectiveKc,IandDcanbedeterminedfromtheultimategainand

ultimateperiodaccordingtothechartabove.


49/58

Appendix V

41 | P a g e

AppendixV. CoanderEffectflyingsaucerexperimentModificationstoUAV

Figure38:ModificationtoPlatform

SomemodificationswerecarriedouttoimprovetheUAVaftertheinitialmotortest.

1. Themotoraswellasthepropellerarerealignedtoensurethatitwasinthehorizontal

plane.

This

is

important

as

slight

misalignment

will

cause

the

propeller

tooscillateandvibrateexceedinglywhenthemotorrotates.Thiswasdoneusing

acircularairbubble.

2. Thespacingbetweenthepetalandtheductwasreducedtoincreaseairflow.3. Theairductwasdoublelayered.Thiswasdonetoimproveonitsrigidityto

maintain

its

cylindrical

structure

during

flight.

As

the

inner

diameter

of

the

duct

wasalsoreducedtoimproveontheairspeed,anyslightdeformationoftheduct

willcausethepropellertocollidewiththeduct.Lastly,theentranceandexitof

theductwaschamferedtoimproveairflow.


50/58

Appendix V

42 | P a g e

J.L.NaudinExperiment

Experimentalsetup

AthrustexperimentdesignedbyJeanLouisNaudinwaspublishedonhiswebsite.

Figure39:J.Naudinsexperimentalsetup

Inhisexperiment,heusedablowertoblowacrossonepetaltosimulateairthat

movesthroughtheairductoverthesurfacesofthepetals.Aweightwasattachedto

theotheredgeofthepetalandwasplacedontoaweighingscale.Ananemometer

wasusedtomeasuretheairspeedatthedifferentlocationsofthepetal.

Results

Theresultthatwasobtainedfromhisexperimentisplottedinthegraphbelow:

Figure40:Naudinsresult


51/58

Appendix V

43 | P a g e

Fromthisplot,itcanbededucedthataminimumairspeedof21m/sisrequiredat

theoutletoftheductedfaninordertogenerate533gofthrust,whichwasthe

overallweight

of

his

platform.

In

other

words,

the

take

off

thrust

required

is

533g.

Experimentconducted:Airspeedmeasurement

ExperimentalsetupandResults

Figure41:Experimentalsetupforairspeedmeasurement

Asimpleexperimentwasconductedtoverifytheairspeedatthedifferentpositions

ofthe

petal,

in

order

to

deduce

the

thrust

that

would

be

generated

according

to

Naudinsresult.

Figure42:Variablesofexperiment


52/58

Appendix V

44 | P a g e

Theairspeedsatthethreelocations,using2differenttypesofpropeller,are

measuredandtheresultistabulatedbelow:

Table2:

Airspeed

test

results

Predictedthrustiscalculatedusingequationthatwasderivedinhisexperiment:

Conclusion

Itwasobservedthatthe2bladepropellerwasabletoproducemorethrustthanthe

3bladepropeller.Themaximumthrustthatcouldbeproducedbyalltheeight

petalswasevaluatedtobeonly143.8g.Thiswasbarelysufficienttoliftoffthe

platformwhichhasanoverallweightof570g,withoutincludingothercomponents

suchasservosandsensors.Thus,theusageofthisplatformforthisprojectwas

ruledout.


53/58

Appendix VI

45 | P a g e

AppendixVI.Autonomouslandingprogram(Basic)Processor

Scheduledproportional

control

'~~~~~~~~SENDER/PROCESSOR~~~~~~~~~~~~~~~~

'{$STAMPBS2pe}

'{$PBASIC2.5}

'{$PORTCOM8}

'~~~~~~~~~~~~~~~~~~SetPin~~~~~~~~~~~~~~~~~~

SO PIN 1 'SerialOutPin

FC PIN 0 'FlowcontrolPin

'~~~~~~~~~~~BaudrateSelect~~~~~~~~~~~~~~~~

#SELECT$STAMP

#CASEBS2PET4800CON16572

T9600CON16468

#CASEBS2PX

T4800CON17197

T9600CON16780

#ENDSELECT

BaudCONT9600

'~~~~~~~~~~~~~ThrottleConfig~~~~~~~~~~~~~~~

'tMin CON 1600

'tMax

CON

1800

tLand CON 1400

tHover CON 1630

throttle VAR Word

throtsend VAR Byte

'~~~~~~~~~~~~~~PIDVariables~~~~~~~~~~~~~~~~

setpoint CON 5

error VAR Word

p VAR Word 'Proportionalterm

'~~~~~~~~~~~~~~~~~PING)))Variables~~~~~~~~~~~~~~

cmConstant

CON

2260

cmDistance VAR Word

time VAR Word

PAUSE500 'ForPlotting

DEBUG"!SPAN0,200",CR 'Altitudeaxis

DEBUG"!TMAX180",CR 'Timeaxis


54/58

Appendix VI

46 | P a g e

DEBUG"!PNTS4000",CR 'Datapointsperplot

DEBUG"!TITLAltituteLog",CR 'Titletheform

DEBUG"!SHFTON",CR 'Plotshiftatmax

DEBUG"!TSMPOFF",CR

DEBUG"!SAVD

ON",CR

DEBUG"!SAVMON",CR

DEBUG"!NAMDPlotData.txt",CR

DEBUG"!NAMMPlotMsg.txt",CR

DEBUG"!PLOTON",CR 'Enableplotting

DEBUG"!RSET",CR 'ResetPlot

DO

PULSOUT15,5 'ToutfromPING)))

PULSIN15,1,time 'TintoPING)))>Timevariable

cmDistance=cmConstant**time 'DistancefromPING)))

DEBUGDECcmDistance,CR 'ForPlotting

error=setPoint cmDistance

IFcmDistance>45THEN 'AugmentProportionalGains

p=2*error

ELSEIFcmDistance


55/58


56/58

Appendix VI

48 | P a g e

DEBUG"!PNTS4000",CR '4000datapointsperplot

DEBUG"!TITLAltituteLog",CR 'Titletheform

DEBUG"!SHFTON",CR 'Allowplottoshiftatmax

DEBUG"!TSMPOFF",CR

DEBUG"!SAVD

ON",CR

DEBUG"!SAVMON",CR

DEBUG"!NAMDPlotData.txt",CR

DEBUG"!NAMMPlotMsg.txt",CR

DEBUG"!PLOTON",CR 'Enableplotting

DEBUG"!RSET",CR 'ResetPlot

DO

PULSOUT15,5 'ToutfromPING)))

PULSIN15,1,time 'TintoPING)))>Timevariable

cmDistance=cmConstant**time 'DistancefromPING)))

DEBUGDECcmDistance,CR

error(current)=setPoint cmDistance 'Calculateerror

p=3*error(current) 'ProportionalGain=3

error(delta)=error(current) error(previous)

d=error(delta) 'DerivativeGain=1

throttle=p+tHover+d MIN1500MAX 1800

IFcmDistance


57/58

Appendix VI

49 | P a g e

Signalgenerator

'~~~~~~~~~RECEIVER/SIGNALGENERATION~~~~~~

'{$STAMPBS2px}

'

{$PBASIC

2.5}

'{$PORTCOM5}

'~~~~~~~~~~~~~~~~~~SetPin~~~~~~~~~~~~~~~~~~

SI PIN 0 'SerialInPin

FC PIN 1 'FlowcontrolPin

PP PIN 5 'PausePin

TP PIN 13 'TrainerPin

'~~~~~~~~~~StampBaudrateSelect~~~~~~~~~~~

#SELECT$STAMP

#CASEBS2PE

T4800CON16572

T9600CON

16468

#CASEBS2PX

T4800CON17197

T9600CON16780

#ENDSELECT

BaudCONT9600

'~~~~~~~~~~~~~~CALIBRATIONDATA~~~~~~~~~~~~~

ch1 CON 1115 'AileronStick:(1775)LeftMid(1375)Right(975)

ch2 CON 1380 'Elevator:(1725)UpMid(1400)Down(1025)

ch4 CON 1400 'Rudder

ch5

CON

2100

'Thermalch6 CON 1400

ch7 CON 1400

sync CON 10305 'Synchropulse

delay CON 375 'Pausepulse

lastdelay CON 260

'~~~~~~~~VariablesfromSerialINPUT~~~~~~~~~~~~~

throttle VARByte

prevthrottle VARWord

throtgen VARWord

DO

SERINSI\FC,Baud,2,timeout,[throttle] 'timeout:2units=0.8ms

throtgen=throttle*10

PULSOUTTP,ch1

PULSOUTPP,delay

PULSOUTTP,ch2


58/58

Appendix VI

PULSOUTPP,delay

PULSOUTTP,throtgen

PULSOUTPP,delay

PULSOUTTP,ch4

PULSOUTPP,

delay

PULSOUTTP,ch5

PULSOUTPP,delay

PULSOUTTP,ch6

PULSOUTPP,delay

PULSOUTTP,ch7

PULSOUTPP,delay

PULSOUTTP,sync

prevthrottle=throtgen 'Storeslastsignal

LOOP

timeout: 'Generatelastsignal

throtgen=prevthrottle

PULSOUTTP,ch1

PULSOUTPP,delay

PULSOUTTP,ch2

PULSOUTPP,delay

PULSOUTTP,throtgen

PULSOUTPP,delay

PULSOUTTP,ch4

PULSOUTPP,

delay

PULSOUTTP,ch5

PULSOUTPP,delay

PULSOUTTP,ch6

PULSOUTPP,delay

PULSOUTTP,ch7

PULSOUTPP,delay

PULSOUTTP,sync

RETURN

Autonomous Landing UAV

Documents

Transcript of Autonomous Landing UAV