REMOTE AREA CLEARENCE DEVICE

REMOTEAREACLEARENCEDEVICE

By

BjornOberg

RahulSachdeva

FinalReportforECE445,SeniorDesign,Spring2018

TA:NicholasRatajczyk

02May2018

ProjectNo.40

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Abstract

Thisreportsummarizesthemotivation,designing,andresearchfindingsoftheRemoteAreaClearanceDevice(RACE).RACEisaBluetoothcontrolledroboticcarthatcomesequippedwithametaldetector,adepthcamera,andaretrievalunitthatallowstheusertosafelydisposeofsmallobjectsontheground.ThemetaldetectorisbasedontheColpittsOscillatordesign,andusestheprinciplesofinductanceandmagneticpermeabilityofobjects.Theretrievalunitiscomposedofabrushandscoopingsystemconnectedtothecarbyaroboticarmpoweredbyadigitalservomotor.Thescoopingsystemisa3DprintedcontainerequippedwithaDCmotortopowerthebushsystemTheresultsshowthatthemetaldetectionsystemworkswellforlargerobjects,butneedstoberesearchedmorebeforeitcanbemadereliablyused.

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Contents

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

2Design........................................................................................................................................................2

2.1PowerModule....................................................................................................................................2

2.2MetalDetectorModule......................................................................................................................3

2.2.1ColpittsOscillator........................................................................................................................4

2.2.2DetectorCoil................................................................................................................................5

2.3ControlUnit........................................................................................................................................5

2.3.1BluetoothModule.......................................................................................................................5

2.3.2Microcontroller...........................................................................................................................6

2.4NavigationUnit...................................................................................................................................7

2.5RetrievalUnit......................................................................................................................................8

2.5.1TheScoopSystem........................................................................................................................8

2.5.2TheBrushSystem........................................................................................................................9

2.6SoftwareControl................................................................................................................................9

3Verification..............................................................................................................................................10

3.1PowerModule..................................................................................................................................10

3.2MetalDetectorModule....................................................................................................................10

3.2.1ColpittsOscillator......................................................................................................................10

3.2.2DetectorCoil..............................................................................................................................11

3.3RetrievalUnit....................................................................................................................................12

3.4ControlUnit......................................................................................................................................13

3.4.1BluetoothModule.....................................................................................................................13

3.4.2Microcontroller.........................................................................................................................13

3.5NavigationUnit.................................................................................................................................14

3.6SoftwareControl..............................................................................................................................14

4.Costs.......................................................................................................................................................15

5.Conclusion..............................................................................................................................................16

5.1Accomplishments.............................................................................................................................16

5.2Ethicalconsiderations......................................................................................................................16

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5.3Futurework......................................................................................................................................16

References..................................................................................................................................................17

AppendixA RequirementandVerificationTable................................................................................18

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1.IntroductionImprovisedExplosiveDevices(IED)andminesposesignificantthreattotheUnitedStatesArmy,withregardtoengineeringoperationsandmaneuversupport[1].Thisprojectwasaimedataddressingthisissue,bydevelopingarobotthatcandetectmetallicobjects,andperformsometaskondetection.Thesecondaspectofthisresearch,whichwassupportedbytheUSArmyConstructionResearchLaboratory,wastofindwhetheraColpittsOscillatorDesigncanbeusedtodeterminethemetallicpropertiesofanobject.Asafirststep,webuiltaBluetoothcontrolledcarthatcandetectmetalobjectsandretrievethemusingabrushandscoopmechanism.ByusingaservomotortoloweracontainerandaDCmotortospinabrushwhichpushesobjectsintothiscontainer,wewereabletobuildafunctioningretrievalsystem.However,wetheresultsshowthattheColpittsOscillatordesignistoounreliabletobeusedalone.

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2Design

Figure1:BlockDiagram

2.1PowerModule

Figure2:VoltageRegulatorCircuitSchematic[2]

Thecircuitrequirestwodifferentvoltagebuses.A7VsupplywasneededfortheServomotorandthe2navigationDCmotors.A4.5VsupplywasneededfortheBluetoothmodule,microcontroller,H-bridges,DCmotorforbrushandtheColpittsOscillator.

TwoLM317Tadjustablepositivevoltageregulatorswereusedtoprovideathe4.5Vand7Vvoltagesfroman11.2VLi-Onbattery.TheLM317Tiscapableofsupplyingamaximumof1.5A.Themaximum

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currentdrawfortherobot,whenallmotorswereoperationalwas0.64A.Thebatteryholdsanenergychargeof2200mAh.Thisensuresatleast3.4hrsofoperation,whichiswellaboveourrequirements.

Figure2showsthecircuitdesignforthevoltageregulator.ThereferencevoltageacrossresistorR1isconstantat1.25V.Theadjustmentterminalcurrentis100𝜇A,whichcorrespondstoaminimumvalueof120ΩforresistorR1.Theoutputvoltageiscalculatedas

V012 = 1.25× 1 +R8R9

(2.1)

UsingEquation(2.1),thevalueofresistorR8wascalculatedtobe624Ωforthe4.5Vregulator,and1104Ωforthe7Vregulator.

ThevalueforresistorR9waschosenas240Ωtoprovideforbetterstability.Stabilityisessentialforthe4.5Vregulator,tominimizethefluctuationinfrequencyproducedbytheColpittsOscillator.Theadditionalcapacitorsaidinthestabilityoftheregulator,andhelpsmoothouttheinherentripplecontentgivingitagoodtransientresponse[2].

2.2MetalDetectorModule

Figure3:MetalDetectorCircuitSchematic

ThemetaldetectionmoduleutilizesaColpittsOscillatorandadetectorcoil.TheColpittsOscillatorwasusedtoproduceafixedfrequencyof100kHzusingacombinationofcapacitorsandaninductor.Thisfrequencyiscontinuouslyfedintothemicrocontroller.Whenthedetectorcoilisbroughtneatametallicobject,itsinductancechangeswhichcausesashiftinthefrequency.Thischangeisdetectedbythemicrocontroller,whichthensendstheuseranalertthroughBluetooth.

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Thespeakerwasremovedfromtheproposeddesign.Itwasdeterminedthataspeakerisnotthemostreliablewaytoalerttheuserinanoisyandoutdoorsetting.ItwasalsoredundantsincethechannelofcommunicationthroughBluetoothwasalreadyimplemented.

2.2.1ColpittsOscillatorTheColpittsOscillatorusesacapacitivevoltagedividernetworkasitsfeedbacksourceandasinglebipolartransistoramplifier(2N2222)asthegainelementwhichproducesthesinusoidaloutput.Figure3showsthecircuitschematicforthemetaldetectormodule.TheinductorisconnectedinparalleltocapacitorsC4andC5inseries,toformthetankcircuit.Oncepowerisapplied,thecapacitorschargeanddischargethroughtheinductor.ThevoltagedevelopedacrosscapacitorC5providestheregenerativefeedbackrequiredforsustainedoscillations[3].Theoscillationsappearamplifiedatthecollectoroutputofthetransistor,andarefedintothecounterpinofthemicrocontroller.ResistorsR4andR5providethestabilizingDCbias.CapacitorC6preventsDCcurrentsfromgoingintothetankcircuit[3].Thetransistorandthecapacitivefeedbackeachprovideaphaseshiftof180°toachieveatotalphaseshiftof360°,anessentialconditionforoscillations[3].

ThisdesignwaschosenoverothervariantssuchastheHartleyoscillatorbecausethisconfigurationresultsinlessselfandmutualinductancewithinthetankcircuit,thusimprovingthestabilitywithintheoscillator[4].

AhigherfrequencywaschosenbecauseitisbetteratinducingEddycurrentsinnon-ferrousobjects,whichdecreasetheinductanceandhencemakesitmoresuitablefordetectingsmallerobjects[4].Whileahigherfrequencyhasasmallerrange,ourprojectonlyrequiredarangeof2 − 3cmtofunction.

Thefrequencyoftheoscillationsis

F =1

2×π× L×C2 (2.2)

where𝐿istheinductanceand𝐶E isthecapacitanceofthetankcircuit.Toproduceafrequencyof100kHz,thecapacitanceandinductancewerecalculatedas5nFand0.506mHrespectivelyusingEquation2.2.

Thevaluesofthecapacitanceofthetankcircuitisgivenby

C2 =CJ×CKCJ + CK

(2.3)

whereCJandCKarethetwocapacitorsinthetankcircuit(seefigure3).Thefeedbackfractionisgivenby

CJCK% (2.4)

Alargeamountoffeedbackreturnedthecircuitcancausethesinewavetobecomedistorted,andasmallamountwillpreventtheoscillationfromgettingstarted[4].ComparingEquations(2.3)and(2.4),CJandCJwerebothcalculatedas10nf.

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2.2.2DetectorCoilThedetectorcoilisaninductormadeupof24AWGwirewrappedaroundahollow,non-conductivespool.Theinductanceofthecoiliscalculatedas

𝐿 =𝑁8×𝜇×𝐴

𝑙

(2.5)

where𝑁isthenumberofturnsincoil,𝐴istheareaofthecoil,𝑙isthelengthofthecoiland𝜇isthepermeabilityoffreespace.UsingEquation2.5,thenumberofturnswasfoundtobe50,radiustobe5.08cmandthelengthtobe2.032cm.

Whenametalwithhighconductivity(suchassilver)isbroughtnearthecoil,itsmagneticpermeabilityincreaseswhichcausesanincreaseinitsinductance[5].Whenametaloflowconductivityisbroughtnearthecoil,Eddycurrentsareinducedinthemetal,whichopposetheelectricfieldoftheinductor[5].Thiscausesadecreaseininductance,whichincreasesthefrequencyproducedbytheColpittsOscillator[4].

Thisdesignworkedforlargerobjects,butthechangeinfrequencywastoosmalltodetectforsmallerobjects.Thus,anewinductorwasbuiltwhichhadamagneticfield4timesasstrongastheoriginalone,andaninductanceof10mH(thecapacitorsvaluesinthetankcircuitwereadjustedtokeepthefrequencyconstant).Themagneticfieldofaninductorisgivenby

𝐵 =𝑁×𝜇×𝐼

𝐿 (2.6)

where𝑁isthenumberofturnsinthecoil,𝜇isthemagneticpermeabilityoffreespace,𝐼isthecurrentintheinductorand𝐿isthelengthoftheinductor.Thisinductor’sdimensionswerecalculatedbycomparingtheEquation(2.6)and(2.5).

2.3ControlUnitThecontrolunitisusedtocontroltheoperationoftherobot’sfunctions.ItconsistsofaBluetoothModuleandaMicrocontrollerchip.

2.3.1BluetoothModuleTheBluetoothmoduleisusedtowirelesslysenddatatothemicrocontrollersothattherobot’sfunctionscanberemotelycontrolled.TheHC-05Bluetoothtransceiverwaschosenduetoitsexcellentrangeofover40ft,anditsrelativelycheapcost.TheBluetoothmodulereceivesdatafromanandroidapp,andcommunicateswiththemicrocontrolleroverUARTinterfaceatabaudrateof9600bps.Asweonlysendasinglebyteofinformationatatime,speedofdatatransferwasnotaconcern.

HC-05hascantolerateamaximuminputsignalof3.3V,whichislowerthantheoutputsignaloftheATmega328microcontroller.Thus,avoltagedividermadeuptworesistorsofvalues1000Ωand2000ΩwasusedtoconnecttheRXpinofthemoduletotheTXpinofthemicrocontroller.Figure4showsthecircuitschematicfortheBluetoothmodule.

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TheHC-05BluetoothmodulecannotconnecttoAppledevices.Wesearchedforothermodules,butfoundoutthatAppledevicescanonlyconnecttoBluetoothdevicesregisteredwiththefirm.Wewereunabletofindanyinexpensivestand-aloneBluetoothmodulethatcanconnecttoAppledevices.

Figure4:BluetoothModuleCircuitSchematic

2.3.2MicrocontrollerATMega328P-Uwaschosentobeourrobot’smicrocontrollerduetoitsinexpensivecost.ThemicrocontrollerreceivesthedatafromtheBluetoothmodule,decodesit,andperformstheappropriatefunctionononeofthemotors.ThemicrocontrollercontrolsthetwoDCmotorsfornavigation,theupwardsanddownwardsmovementoftheServomotor,andtheDCmotorforthebrush.

TheSignalinputoftheServomotorwasconnectedtoPortB,asitrequiresaPWMwaveinordertohaveprecisecontroloverthedegreeofrotation.

Additionally,themicrocontrollercontinuouslyreadsthefrequencyoftheColpittsOscillator,andcomparesitwiththefixedfrequencyof100kHz.Whenthefrequencychangesbymorethantheaveragefluctuation,amessageissenttotheappthroughBluetoothtoalerttheuserthatmetalhasbeendetected.

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2.4NavigationUnit

Figure5:NavigationUnitCircuitSchematic

ThenavigationunitcontrolsthemotionoftherobotusingtwoDCmotorsforthetwowheeltracks.SinceDCmotorsareaninductiveload,themotorsweredrivenusingtheL293DH-bridgeasthepinsoftheATMega328canhandleamaximumcurrentof40mA.ThepositiveandnegativepinsofthebothmotorswereconnectedtotheHbridge,whichreceivesitsinputfromthePortBoftheMicrocontroller.Thus,eachmotorcanbedrivenforwardandbackwards.Therobotisabletoturnleftandrightbymovingthemotorsintheoppositedirection.Figure5showsthecircuitschematicofthenavigationmodule.

ThenavigationunitalsohasanIntelRealSensecamera,whichismountedontherobot.Thepurposeofthecameraistoaidinnavigationbyprovidingrealtimevideofeedbacktotheuser.ThecamerasendsthevideostreamoveritsownWi-Finetwork,whichcanbeviewedintheapp.Thiscamerawaschosenduetoitsadvancedfunctionalitiessuchasdepthanalysisandfacialrecognition.Thenextstepintheprojectistousethesecapabilitiestoimplementsemi-autonomousnavigation.

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2.5RetrievalUnitTheretrievalunitisusedtoretrievesmallobjectsfromtheground.TheunitconsistsofaServomotor,twowoodenarms,a3Dprintedcontainer,abrushandaDCmotortorotatethebrush.Figure6showsthePhysicalCADDesignoftheretrievalunit.

Intheinitialdesign,thecoilwasinfrontoftheretrievalunit,onthesamesideofthecar(seeFigure6).However,thisorientationcausedanimbalanceinweightwhichcausedtherobottotipover.Thus,thedetectorcoilwasplaceatthebackoftherobottobalancetheweight.

Figure6:CADDesignoftheRobotwiththeRetrievalUnit

2.5.1TheScoopSystemThe3Dprintedcontaineris9cmwideandisconnectedtothetwowoodenarmswhichareconnectedtotheServomotor.Themicrocontrollerrotatestheservomotor,whichenablesittolowerthecontaineruntilitlaysflatontheground.Toprovidesomeflexibilitytothecontainerandtoaddrobustness,springsandstopperswereaddedtothebackofthecontaineratitsconnectionpointwiththearms.Thisallowedthecontainertoadjusttosmallvariancesinthegradientoftheterrain.Theserubberstoppersalsopreventthecontainerfromsmashingtoohardontheground,thusreducingtheriskofthesystembreakingapart.

Thepositionoftheservomotorisupdatedby1degreeatatime,inordertoprovideacontinuous,jerk-freemotion.Thisreducesthepossibilityoftheobjectdroppingfromthecontainerwhenitisbeingscoopedup.

Keepinginmindthatwewoulddesignabiggerretrievalunitinthefuture,ahightorqueServomotorofTorque20kg-cmwaschosensothatlargerobjectscouldbepickedup.

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2.5.2TheBrushSystemThecontainerhasahorizontallypositionedbrushattachedinfrontofitwhichisconnectedtoaDCmotor.Thismotorspinsthebrush,whichpushesanobjectintothecontainer.Abrushwiththickplastichairwaschosensothatitcanpushtheobjectwithastrongerforce.Thebrushhangs1.3cmfromthebaseofthecontainer.Thus,themaximumheightoftheobjectsthatcanberetrievedis1.3cm.

Initially,theDCmotorchosenwashighspeedmotor.Itdrew1.2Aofcurrent,andwouldcausethenavigationmotorstoslowdownifoperatedsimultaneously.Italsohadalowtorque,andwouldgetstuckiftheobjectwasheavy.ThismotorwasreplacedwithahightorqueDCmotor,whichranat10000RPM.Thenewmotorwasabletoprovidetheobjectwithenoughmomentumtoovercomethefrictionalforceactingonit.

Inordertopreventtheobjectsfromfallingdownwhenthecontainerwasbeingliftedup,asmallbumperwasbuiltonthebaseofthecontaineratasmallincline.Thisinclinedidnotstoptheobjectfromenteringthecontainer,butpreventedthemfromfallingout.Thebaseofthecontainerwasmadeasthinaspossible(1mmthick)whilemaintainingthestructuralintegrity,toallowthesystemtopickupflatobjectssuchaskeys.

2.6SoftwareControlInordertocontrolthefunctionsoftherobot,anandroidappwasdeveloped.Thisappusedthephone’sBluetoothclienttoconnecttotheHC-05Bluetoothmodule.Therearefourpushdownbuttonstocontrolthenavigationsystemanddrivetherobotforward,backward,leftandright.Therewerefouronclickbuttonstocontroltheretrievalunit;twotorotatetheservomotorupanddown,andtheothertwotostartandstopthebrush.

Ourproposeddesigndidnotincludeamobileapplication.Therobotwasmeanttobecontrolledthroughalaptop.Wedidnotthinkitwasfeasibletocontroltherobotwithalaptopastherobothasarangeofover30feet.Thus,anandroidappwasdevelopedtoprovideabetteruserexperience.

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3Verification

3.1PowerModuleTheresultsforthetwovoltageregulatorsareshowninTable1.

Table1:VoltageRegulatorResultsRegulator Observed

VoltageMaximumFluctuationovera

Periodof30minutes4.5V 4.52V 0.44%7V 7.1V 1.12%

3.2MetalDetectorModule

3.2.1ColpittsOscillatorAfrequencyof98.614kHzwasobservedwithanerrormarginof0.57%usingtheinitialdesign.Thissignalwassustainable,andremainedinthisrangeforatleastthirtyminutes.Thiswaswithinouracceptablelimits.Figure7showstheOscilloscopereadingofthesignal.Figure8showsthesamesignalwhentheinductorisclosetoametallicobjectofVolume110.12𝑐𝑚8.

Figure7:OscilloscopeReadingof98kHzsignal

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Figure8:SignalWaveonOscilloscopewhentheobjectisnearametallicobject

3.2.2DetectorCoilWiththeinitialdesign,thesmallestobjectthatcouldbedetectedwasacuboidoflength3cm,width1.5cmandheight2.7cm.Thiswasbiggerthantheminimumsizerequirementsforourdesign.Thus,anewinductorwasbuiltwithamagneticfieldfourtimesasstrongasthepreviousone.Alongwiththis,differentfrequenciesweretested,theresultsofwhichareshowninTable2.

Table2TheChangeinfrequencyforDifferentFrequenciesInductance

(𝐦𝐇)Capacitance

(𝐧𝐅)ObservedFrequency

(kHz)

FluctuationPercentage

PercentageChangeduetobrassobject

ofVolume𝟒. 𝟗𝟐𝒄𝒎𝟐

PercentageChangeduetobrassobject

ofVolume𝟏𝟏𝟎. 𝟏𝟐𝒄𝒎𝟐

0.546 5 98.6 0.57 - 1.920.546 2.5 143.4 0.88 1.02 2.3810 5 21.8 0.49 - 1.1410 2.5 36.2 0.66 - 1.3410 0.235 94.4 0.84 1.17 2.37

Thenewinductordidnotsatisfythedesignrequirementsoftheminimumobjectsizeeither.Theresultsshowthatwhileastrongermagneticfieldincreasesthechangeinfrequency,theincreaseinaccuracyismarginal.Frequencyplaysabiggerroleindeterminingtheminimumsizeoftheobjectthatcanbedetected.

Atesttocomparethechangeinfrequencyatdifferentdistancesfromtheinductorwasalsoconductedforthetwoobjects.Thefirstobjectwasacuboidbrassobjectofvolume4.92cm8.Thesecondobjectwasabrasscylinderofvolume110.12cm8.ThesearereferredtoasObject1andObject2respectivelyinFigure9,whichshowsthefrequencyagainstthedistanceoftheobjectfromtheinductor.Wefoundthatthelargeobject(Object2)couldbedetectedatamaximumdistanceof4cm,whereasthesmallerobject(Object1)wasabletobedetectedatamaximumdistanceof1cm.

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Figure9:Relationshipbetweenchangeinfrequencyanddistancefrominductor

3.3RetrievalUnitTheretrievalunitwastestedwithseveralobjectsofdifferentshapesandsizes.Table3showsthedifferentobjectswhichwereusedastestcases.Eachoftheseobjectswastested15times.TheresultsfortheretrievalunitareshowninFigure10.Thesystemworkedverywellfornailsandbolts,whichwastherequirementinourproposeddesign.ThesystemstruggledtopickuplargecubicalobjectssuchasLegopieces,astheywouldsometimesgetstuckunderthebrushdependingontheangleofapproach.

Table3:TestCasesfortheRetrievalUnit

ObjectName Shape DimensionsWasher Thinandflat Height=0.3cm,Radius=1.7cm

HouseKey(withsmallkeyring)

Thinandflat Thickness=0.3cm,length=3.1cm

Bolt Round–abletoroll

DiameterofHead=1.27cm,length=1.9cm

Screw Round–abletoroll

DiameterofHead=0.9cm,length=5.8cm

Legoblock Cube–notabletoroll

Side=1.2cm

CarKey Misc.–notabletoroll

Height=2.2cm,Length=5cm,Width=3cm

96

98

100

102

104

106

108

110

Infinity 5 4 3 2 1 Insidethecore

Freq

uency(kHz

)

DistanceFromCore(cm)

Frequencyv/sDistance

Object2 Object1 BaseFrequency+MaximumError

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Figure10:ResultsFortheScoopingandLiftingofVariousObjects

3.4ControlUnit

3.4.1BluetoothModuleSeriesofdatawassenttothemicrocontrollerwhichwasbeingdisplayedontheSerialMonitor.Itwasverifiedthatthecorrectdatawasreceived.TherangeoftheBluetoothModulewasverifiedtobeatleast35feet.

3.4.2MicrocontrollerTheMicrocontrollerwasabletocontrolthenavigationunit,andcommunicatewiththeBluetoothmodule.

SincethedesignoftheColpittsOscillatorwasnotfinisheduntilmuchlaterinthecourse,thecodetoreadthefrequencycorrectlyintothemicrocontrollerwastestedusingasinewavegeneratedbyafunctiongenerator.ThefunctionwasalsodisplayedontheoscilloscopeanditwasverifiedthatthefrequencywasbeingreadcorrectlybytheAtMega328.

ThissamecodedidnotworkwiththeColpittsOscillator.Duetothetimeconstraints,wewerenotabletofixthiserror.Webelievethatthecauseofthiserrorwasthefactthatthesignalwasnotsampledcorrectly,thusresultinginanincorrectreferenceDCvoltage.Thewavegeneratedbythefunctiongeneratorisclosetoaperfectsinewave,whichiswhythiserrorwasnotseenintheinitialtests.InthecaseofaColpittsOscillator,thewaveisnotaperfectsinewave,andincorrectsamplingcouldbethepotentialcauseoftheerrors.

02468101214

Washer HouseKey(withasmall

ring)

Bolt Screw LegoBlock CarKey

PerformanceofRetrievalUnit(15Tries)

Scooped ScoopedandLifted

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3.5NavigationUnitWeverifiedthatthecarcoulddriveforward,backward,leftandrightataspeedofatleast2.5inches/sec,withthefullweightoftheretrievalunitandthemetaldetector.

3.6SoftwareControlItwasverifiedthattheAppcouldconnecttotheBluetoothModuleandcontrolalloperationsoftherobot.

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4.CostsOurlaborcostisestimatedatanhourlyrateof$35perhour,12hoursperweekfortwopeople.Theprojectwas12weekslong.Thetotallaborcostsaregivenby

𝑇𝑜𝑡𝑎𝑙𝐶𝑜𝑠𝑡 = 2×$35ℎ𝑜𝑢𝑟

×12ℎ𝑜𝑢𝑟𝑠𝑤𝑒𝑒𝑘

×12𝑤𝑒𝑒𝑘𝑠×2.5 = $25,200(4.1)

Table4showsthecostofthepartsusedinmakingtheproject.

Table4:CostAnalysisofPartsPart Manufacturer Quantity RetailCost

($)Bulk

PurchaseCost($)

TotalPrototypeCost($)

ChassisandMotors MountainArk 1 49.99 44.99 49.99Servo LewanSoul 1 21.99 20.99 21.99

BluetoothHC-05 DSDTech 1 9.99 7.99 9.99ATMega238-PU Atmel 1 2.28 1.68 2.28LiPoBatteryPack Turnigy 1 10.99 10.99 10.99

LM317T TexasInstruments 2 2.03 1.38 4.0624AWGWire Remington

Industries75feet 0.05 0.03 3.42

2N2222ANPNTransistor MclglcM 2 0.19 0.03 0.38IntelRealSenseD415 Intel 1 149.99 149.99 149.99AssortedComponents(Resistors,Capacitors,

etc.)

KOASpeer 1 9.99 9.99 9.99

PCB PCBWay 1 5.6 0.87 5.63DPrinting CERL 1 7.00 7.00 7.00

Total 275.68Ourtotalcostofpartfortheprototypeis$275.68.Thusthetotalcostofdevelopmentofaprototypeis$275.68 + $25,200 = $25,475.68.

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5.Conclusion

5.1AccomplishmentsOurprojectworkedasintendedforthemostpart.Thetwomajorcomponentsofoursystem;retrievalandmetaldetectionunitworked,eventhoughtheirperformancewasnotasgoodasexpected.Wewereabletobuildaplatformwhichhasaneasilyexpandablemodulardesign.Thetechniqueswehavetestedcanbemademorerobustthroughfurtherresearchandexperimentation.

5.2Ethicalconsiderations

Oneoftheethicalchallengesposedbyourprojectisthewayitisused.Sinceitisarobotcarthatcanbecontrolledwirelessly,apotentialissueoftrespassingpropertyarises.TheIEEECodeofEthicsstatesthatoneshouldavoidtoinjureotherpeopleandtheirproperty[6].Thecarcouldalsopossiblyinjurepeopleifitisnotinthesightoftheuserduringoperation.Wehaveequippedthecarwithacamera,sothattheusercanoperatethecarevenitisnotintheirsight.Topreventthemisuseofthisrobot,wehavedecidedtouseaBluetoothreceiverwithlimitedrangeofabout40feet.Inordertopreventpossibleinjuriestopeopleanddamagetoproperty,wehaveusedmotorsthatlimitthespeedofthecarto2.5inchespersecond.

Thecarusesalithiumionbattery,whichposesapotentialsafetyhazard.Topreventthebatteryfrommovingaroundduringtheoperationofthecar,itissecurelyplacedonthechassisofthecar.

Ourprojecthastwomovingarms,andarotatingbrush.Topreventpossibleinjuries,wehavelimitedthetorqueproducedbytheservomotor.Thebrushisrotatedatalimitedspeedof1degreepersecondsothatitmaynotinjureanyone.Further,toensurethatnodamagetopropertyisdone,theretrievalsystemisequippedwithrubberstopperssothatthecontainerdoesnotsmashintotheground.

Wearealsoresponsibleforbeinghonestabouttheclaimswemakeabouttheproject[6].Toadheretothisguideline,wewillbeverycarefulaboutthesuggestedusageofourproduct.Untilitcanmeettheminimumaccuracyguidelinesfordetectinglandmines,thesuggestedusagewouldbestrictlyforhomeandrecreationaluse.

TheIEEECodealsostatesthatonemustholdparamountthesafetyofthepublic[6].Webelievethatwehavemadeanexcellentcosteffectiveplatform,thatcanpossiblyhelppeopleinwartornregions.Whileitssuggesteduseisinhomes,itsfeaturescanbeexpandeduponastheproductisagreatplatform.

5.3FutureworkThenextstepinthisprojectistofullyintegratethemetaldetectorcircuitwehavebuiltintooursystem,eventhoughitdoesnotworkasweinitiallyexpected.WewouldthenusetheDepthAnalysisfeatureoftheIntelCamerainconjunctionwithproximitysensorsinordertoimplementsemi-autonomousnavigation,sothattherobotcanlookforobjectsitselfwithlimitedhumancontrol.

Wewouldalsoliketobuildamorerobustretrievalunitbyexperimentingwithvacuumpumps,electromagnets,verticalbrushes,androboticarmstopickobjectsup.Finally,we’dliketotestalternatemetaldetectiontechniques,suchascapacitivesensing,beatfrequencyoscillatorsetc.

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References[1] Siegel,R.(2002).Landminedetection-IEEEJournals&Magazine.[online]Ieeexplore.ieee.org.

Availableat:http://ieeexplore.ieee.org/document/1048979/[Accessed6Feb.2018].

[2]Electronics-Tutorials.(n.d.).VariableVoltagePowerSupply.[online]Availableat:https://www.electronics-tutorials.ws/MiscellaneousCircuits/variablevoltage-voltage-power-supply.html[Accessed19Feb.2018].

[3]Vlab.amrita.edu.(2011).ColpittsOscillator:harmonicMotionandWavesVirtualLab.[online]Availableat:http://vlab.amrita.edu/?sub=1&brch=201&sim=1142&cnt=1[Accessed20Feb.2018].

[4]Electronics-Tutorials.(n.d.).TheColpittsOscillator.[online]Availableat:https://www.electronics-tutorials.ws/oscillator/colpitts.html[Accessed18Feb.2018].

[5]Electronics-Tutorials.(2018).InductanceofaCoil.[online]Availableat:https://www.electronics-tutorials.ws/inductor/inductance.html[Accessed19Feb.2018].

[6]Ieee.org,"IEEECodeofEthics",2018.[Online].Availableat:http://www.ieee.org/about/corporate/governance/p7-8.html.[Accessed24March.2018].

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AppendixA RequirementandVerificationTable

Table5:RetrievalUnit:RequirementandVerifications

Sub-Module

Requirements Status

ScoopSystem

1. Thelowerpositionofthearmsshouldlaythecontainerflatontheground.

2. Thestoppershouldbeabletostopthearmswhenitreachestheground,andpreventitfrombumpingintotheinductor’sholderwhilegoingup.

1. Item1:Verified.

2. Item2:Verified.

BrushSystem

1. Thebrushshouldbeabletospinwhilehangingabovethebottomedgeofthescoopsystemby0.5" ± 5%.

2. Thesystemshouldbeabletopickupanythingwithdimensionsof(𝑊×𝐷×𝐻)3”×1”×0.5”withanaccuracyofatleast75%.

3. Thesystemshouldpreventobjectsfromfallingoutofthecontainerwithasuccessrateof80%.

1. Item1:Verified.

2. Item2:Verified.

3. Item3:Verified.

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Table6:PowerModule:RequirementandVerifications

Sub-Module

Requirements Verification Status

Li-OnBattery

1. Thebatterymustbeabletostoreenoughchargetoprovideatleast640mAcurrentat9V-11V,foratleasttwohours.

1. VerificationProcessforItem1:a. UseaVoltmetertoverify

thataLi-Onbatterysuppliesbetween9-11V.

b. Applyaconsistentdrawof640mAagainstthebatterypackfortwohours,andensurethatthatthevoltageoutputiswithintherange9Vto11V.

1. Item1:Verified.

VoltageRegulator-4.5V

1. Theregulatorshouldprovide4.5V±5%froman9-11Vsource.

1. VerificationProcessforItem1:a. InputVoltage:Thecircuit

wasconnectedtothepowergenerator,whichwassetat11V.TheinputvoltageacrosswasmeasuredusingamultimeterinDCvoltagesetting.Thisvoltagewasreadtobe11V.

b. OutputVoltage:TheoutputvoltagewasmeasuredusingamultimeterinDCvoltagesetting.Thisvoltagewasstableat4.52V.

c. Stability–Theoutputvoltagewasmeasuredwhiletheinputvoltagefromthepowergeneratorwasreducedto9V.Thereadingwasstable

1. Item1:Verified

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VoltageRegulator-7V

1. Theregulatorshouldprovide7V±5%froman9-11Vsource.

1. VerificationProcessforItem1:d. InputVoltage:Thecircuit

wasconnectedtothepowergenerator,whichwassetat11V.TheinputvoltageacrosswasmeasuredusingamultimeterinDCvoltagesetting.Thisvoltagewasreadtobe11V.

e. OutputVoltage:TheoutputvoltagewasmeasuredusingamultimeterinDCvoltagesetting.Thisvoltagewasstableat7.1V.

f. Stability–Theoutputvoltagewasmeasuredwhiletheinputvoltagefromthepowergeneratorwasreducedto8V.Thereadingwasstable.

1. Item1:Verified

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Table7:NavigationUnit:RequirementandVerifications

Sub-Module Requirements Verification Status

Motors 1. The DC motors must be able to operate at 7V±5%. The microcontroller must be able to control the movement of each DC motor. This includes turning it on/off, driving it forward and driving it backward.

2. They must be able to move the full weight of the car and the metal detector circuit, at a speed in the range of 2 to 2.5 inches per second.

1. Verification Process for Item 1: a. Power was applied to

the circuit and the microcontroller was programmed to send the following signals to Pin 14, Pin 15, Pin 16 and Pin 17: LLLL - Both motors off HLLL – Left DC Motor forward LHLL – Left DC motor Backward LLHL – Right DC Motor Forward LLLH – Right DC Motor Backward

2. Verification Process for Item 2: a. Using an inch tape,

mark a distance of 5 ft., clearly marking the start and the end lines.

b. The robot car, with all the modules attached, should be able to reach the endpoint from the start point in 24-30 seconds.

c. Adjust the amount of voltage applied by changing the resistor values for the 7V regulator, until the speed is within the tolerance level.

1. Item 1:

Verified.

2. Item 2: Verified.

IntelRealSense

1. The camera should be able to create its own Wi-Fi network, and

1. Verification Process for Item 2: a. Configure the camera


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Camera connect to a laptop with a range of at least 30 ft.

2. The camera should be able to transmit data over this Wi-Fi connection.

to create its own Wi-Fi network.

b. Ensure that a laptop can connect to this network.

c. Move the laptop at least 30 feet away from the camera. Ensure that the laptop can still connect the Wi-Fi network.

2. Verification process for Item 3: a. Connect the camera to

a laptop, and turn its video feed on.


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Table8:MetalDetectorUnit:RequirementandVerifications

Sub-Module

Requirements Verification Status

DetectorCoil

1. Themagneticfieldareacreatedbytheinductorcoilshouldbebigenoughtogiveitarangeof3-5cm.

1. VerificationProcessforItem1:a. Placeascrewnailof

size8Dwithaheaddiameterof0.28inchesatadistanceof4-5cmawayfromthecoil,whilethecircuitisbeingpowered.

b. Connectthecollectorpinoftheamplifiertotheoscilloscope.

c. Thechangeinfrequencyduetothemetallicobjectmustbegreaterthanathresholdfrequency,whichwillbefoundthroughexperimentation.

1. Item1:Failed.Nochangeinfrequencywasobservedduetosmallmetallicobjectssuchasnails,ringsetc.Alargermetallicobjectcausedanincreaseinfrequencyof2kHz.

ColpittsOscillatorCircuit

1. Theoscillatorcircuitmustprovideasteadyoscillationinthe100kHz±5%rangewhennometalisneartheinductioncoil.

1. VerificationProcessforItem1:a. Connectthecollector

pinoftheamplifiertotheoscilloscope.

b. Apply4.5Vofpowertothecircuit,whileensuringthatthereisnometallicobjectwithin20cmoftheinductorcoil.

c. Thefrequencyoftheresultantsinusoidalsignalshouldbe100kHz±5%.

d. Adjustthecapacitorvaluesandthenumberofturnsinthecoilto

1. Item1:Verified.

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2. Theoscillationshouldbesustainableforatleasttwohours.

gettheresultwithintolerance.

2. VerificationProcessforItem2:e. Connecttheoutput

signalfromtheoscillatorcircuittoafrequencycounter.

f. Apply4.5Vofpowertothecircuit,whileensuringthatthereisnometallicobjectwithin20cmoftheinductorcoil.

g. Thereadingonthefrequencycountershouldstaywithin5%of100kHzforatleasttwohours.

2. Item2:Verified

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Table9:ControlUnit:RequirementandVerifications

BluetoothModule

1. The Bluetooth receiver must be able to transfer data to and from the microcontroller over UART

2. It must have a range of

at least 25 ft.

1. Verification process for Item 1: a. Configure the

Bluetooth module with the microcontroller using the UART connection, by connecting the TXD and RXD pins to port D of the microcontroller.

b. Set the baud rate to 9600 bps (default).

c. Connect the Bluetooth module to a laptop.

d. Send test data from the laptop.

e. Verify that the test data was received correctly by the microcontroller.

2. Verification Process for Item 2: a. Connect the module to

a laptop. The status LED should turn on.

b. Move the laptop at least 25ft. away from the module. The LED should remain on.



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Microcontroller 1. The microcontroller must be able to receive data from the Bluetooth receiver over UART.

2. The microcontroller must be able continuously compare the measured frequency and the fixed frequency, and trigger the speaker when the difference is greater than the threshold.

1. Verification process for Item 1: a. Configure the

Bluetooth module with the microcontroller using the UART connection, by connecting the TXD and RXD pins to port D of the microcontroller.

b. Set the baud rate to 9600 bps (default).

c. Connect the Bluetooth module to a laptop.

d. Send test data from the laptop.

e. Verify that the test data was received correctly by the microcontroller.

2. Verification process for Item 2: a. Store an experimental

threshold frequency (10kHz) and a fixed frequency (100kHz) in the microcontroller.

b. Connect the port D of the microcontroller to the function generator in the sine wave mode.

c. Configure the sine wave generator to generate a wave of 100kHz.

d. Connect the speaker and configure the software so that the microcontroller triggers the speaker if the difference between the fixed frequency and the measured frequency is greater


Item 2: Verified

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than the threshold. e. Now power the

microcontroller chip. f. After 5 minutes,

decrease the output of the function generator by 10kHz. The speaker should turn on.

REMOTE AREA CLEARENCE DEVICE

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