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1. 1
Chapter One : Introduction1
1.1 Statement of the problem:-
Thisprojectisto designa special vehicle thattransformingtoquadpodwhichis
fourlegwalkingrobot.The purpose isto overcome obstaclesthatcarcannot go through.
1.2 Objectives:-
We believe thisprojectisimportantbecause thisscaledversionof vehiclecan
access places(mountainandbumpyroads) thatthe vehicle cannotgetthroughwithtypical
wheels.Thisprojectmerelyshowsthe basicconceptof the transformable vehiclebutitmay
helpthe vehicle to be usedinmore varioussituationsinthe future.The maingoal istomake
a miniature vehicle thatcanbe transformedintothe Quadpod,the vehicle withfourlegs,
whenitmeetsanobstacle that can't be overcome withtypical wheels.The obstacle couldbe
any place difficulttomove byvehicle butwe're mainlyfocusingonroughunpavedroador
hill.The projectwill consist4legs(2on each side),whichwill onlybe activatedwhenthe
vehicle isin“Quadpod”mode anduse itto overcome obstacle.
1.3 Scopeofthe work:-
Our projectmainlyfocusontransformingfromvehiclemode toquadpodmode and
howto keepthe projectbalancedinbothmodes.The projectcan be usedinmanyways like
movingonrough roads,hills,andforests.Italsocan be usedinhard situationslike inafire
incidenttosearchfor people inside the buildingwithoutthe needforhumanstogetinside
(thiscan be done by addinga camerato the robot).
1.4 Benefits:-
- Vehicle canovercome obstaclessuchasbumpyroad,mountain,jungle andforest,which
typical car can't getthrough.
- The vehicle cansense obstaclesbyusingtouchsensorinthe bumpersothatit can
automaticallytransform.
- Bothcar mode and Quadpodmode are fullycontrollable byuserinterface.
- Multifunctional vehicleformultipurposeuse.
- Forcefullytransformable whendriverdesires.
1.5 Organization:-
We organizedthe projectinthe waythe ABET askedfor as follow,we startedwith
the introductionasthe firstchapterto talk aboutthe projectbriefly.Then,forthe second
chapterwe addedthe constrainsand code/standardsrelatedtothe project.After thatwe
wrote the literature reviewasthe thirdchapterwhichtalkaboutsome paperand research
we didabout our project.Thenthe fourthchapterwasthe methodologywhichwe talked
aboutthe projectindetailsandshowedwhatcomponentswe are usingforourproject.
thenwe summarizedall the collecteddatainthe fifthchapterunderthe resultsandanalysis

2. 2
subject.Theninthe sixthchapterwe discussedsubjectsaboutthe projectbriefly.Finally,in
the seventhchapterwe wrote the conclusionabout ourproject.

3. 3
Chapter Two: Constrains , Standards/Codes andEarlier Course
work
2.1 Constrains:-
We facedseveral problemsinthe project forexample :
 Dealingwiththe Autocad.
Overcome :We have to solve thisproblembylearningthe programandget helpfrom
graduate electrical engineersinordertolearnit .
 Calculatingthe centerof mass
Overcome :We got helpfromMechanic & Mechatronicsteachers.
 Buy the componentsneededforthe project.
Overcome :We boughtthe componentthroughinternetbutthe shippingwilltake time .
 the legshave enoughstrengthtoliftupthe whole vehicle.
Overcome :We didsome calculationsshownlateron.
2.2 Standards/Codes:-
We have implementedourprojectaccordingto:
1- National Electrical SafetyCode (NESC)
2- IEC (InternationalElectrotechnical commission) standards
3- BS EN 61000-6-3,4 (Electromagneticcompatibility,Genericemissionstandard
4- BS EN 1127, parts1,2 (Explosiveatmospheres,Explosionpreventionandprotection)
5- BS EN ISO12100 (Safetyof machinery,General principlesfordesign,Riskassessment
and Riskreduction)
2.3 Earliercoursework:-
We tookmanycoursesthat are relatedtoour project, suchas:
1- Control systems
2- Electrical machinery
3- Control of electrical machinery (Drive)
4- Analysissystemsandsignals
5- Electrical circuits
6- Electroniccircuits
7- Electrical measurementsand sensors
8- Micro processersandcontrollers.

4. 4
Chapter Three: Literature Review
We have read some worksrelatedtoourprojecton the internet,we mostly
dependedonvideostolearnmore aboutwhatwe want.We mainlyusedWikipedia.org
,Youtube.com,Google.com, Letsmakerobots.com andLynxmotion.nettogetresources.
Goingthroughthese websites gave us more clear ideasaboutwhatisrequired forour
project, which helped ustobenefitfromotherexperiences toavoidsome problemswith
our design.
We alsohad a lookon the roboticssubjectinthe Mechatronics engineeringdepartmentin
our universitywhichhelpedustounderstandsome conceptsaboutrobotsandits
simulation.
Let usnow considersome of ourresearchwork; we have seenmanyvideosonYouTube
aboutthe robots. we have seenmanytypesof robots withdifferentnumberof legs,also
manyvideoswere actuallyveryuseful becausetheyhave consideredthe movementof the
single legof the robotveryclearlywhichmakesthe conditionmore obvioustous.
We alsotooka lookonsome datasheetsrelatedtoourprojectcomponentssuchasthe
ArduinoMega, Sharp IR sensor,and mechanical characteristicsof the pushbuttonforthe
legs'sensor.
we have alsoread aboutthe legs'designof the robot .
alsoit tooka lotof time to understand how tokeepthe balance of the robot , usingthe
centerof mass concept.
As forexamplesonotherprojects;there wassome usingreadykitfora close projecttoours
so we useditto learnmore about the legsjointandbalancing.
Andthere wasanotherprojectthat has the micro-controller design as main station, each leg
has two degrees of freedom (DOF). Andin the endof the projectitgave a suggestionfor
motorstype.
Withthese twoprojectsandother similarprojectswe designedourrobotschematic(refer
to Appendix A).

5. 5
Chapter Four: Methodology
4.1 BlockDiagramandFunctions
Fig. 1: Block Diagram
- Main station (ArduinoMega): The microprocessorthatgetssignal fromthe wireless
remote controllerandcontrol all of the vehicle'smotors.Also,itreceive the signalfromthe
sensorandevaluate.
- Wheel movementsystem:Thissystemcontrolswheelsmovement.There istwo
continuousrotationmotorsoneachwheels.Bychangingpulse width,speedanddirection
can be controlled.
- Leg movementsystem: Thissystemcontrolslegmovement.There are twostandard
motorson each leg.Each controlsX-axisandY-axisof the leg.Bychangingpulse width,we
can make the motorto turns to certainangle.
- Sensor control system:This systemcontrolssensors.Sensorsonbumpercontrols
transformingandsensorsonlegscontrolsthe movementof leg.
- User control system:This systemsendsignal fromthe usertothe mainstationto control
the vehicles.There is7differentserial datafromthe userinterface andeachcommends
differentmotions.
- Power: The powerforthe ArduinoMegais suppliedby9V battery,andtwo7.4 Lipo
batterieswill supplythe powerfor5 motorseach.

6. 6
4.2 Schematics:-
While the projectisinvehicle mode,itcango forward,left,rightdependson
the signal receivedbyIRreceiver.Itcanalsotransformintoquadpoddependonthe signal
receivedfromproximitysensorandthe IR receiver.The RightandleftWheel motorsare
continuousrotationmotorandtheyare incharge of controllingmovementof the vehicle,
while the 4 vertical movementmotorsare standardservomotorsandtheyare incharge of
transformation. All the motorsare controlledwiththe lengthof the pulse givenbythe main
station;thus,the motorsare connectedtothe PWM outputof the mainstation.While the
projectisin quadpodmode,itcan go forward,turnleft,turnrightdependsonthe signal
receivedbyIRreceiver. All theseoperationsare done usingthe 8standard servomotor,
where 4 of themare in charge of vertical movementof legsand4 incharge of horizontal
movement.Again,all the motorsare controlledwiththe lengthof the pulse givenbythe
mainstation;thus,the motorsare connectedtothe PWM outputof the mainstation.The
schematicisattachedon the Appendix A.
4.3 FlowCharts:-
Duringthe semester,we gatheredand made flow chart(refertoAppendixF) for
vehicle mode andQuadpodmode of the project.The flow charton AppendixF isthe flow
chart for vehicle mode we made duringthattime.Basedonthe flow chart,while the project
isin vehicle mode,itcango forward,left,right,andbackwarddependsonthe signal
receivedbyIRreceiver. Itcan alsotransformintoQuadpoddependonthe signal received
fromproximitysensorandthe IRreceiver. The continuousrotationmotorare incharge of
controllingmovement of the vehicle
The same time we made flowchartfor vehicle mode,we alsomade flow chartforQuadpod
mode(refertoAppendixF).While the projectisinQuadpodmode,itcan goforward,go
backward,turn left,turnrightdependsonthe signal receivedby IRreceiver.All these
operationsare done usingthe 8 standardservomotor,where 4 of themare incharge of
vertical movementof legsand4 in charge of horizontal movement
All the motorsare controlledwiththe lengthof the pulse givenbythe mainstation;thus,
the motors are connectedtothe PWMoutputof the mainstation.
We alsodida simulationforthe projectdesignusingAutoCAD(AppendixD,E) andalsotried
usingsome animationprogramstoshow itmovementrefertoAppendix E.

7. 7
4.4 DetailedDescriptions:-
4.4.1 Main Station
Fig. 2: Arduino Mega 2560
ArduinoMegais the mainstationforthe design.Itshouldreceivethe signal fromremote
controllerandgenerate pulse signal forthe control of the motors.ArduinoMega
recommendedvoltage is 7~12V,so we will use a 9V battery to helpbetterperformance,
whichisregulatedto5Vbythe regulatorinstalledinsideArduinoMega. The Arduino Mega
shouldhave a capabilityof supportingsynchronizedsignaltoall componentsconnectedto
it.
On the station,the IR receiverforthe remote controllingwill be connectedto5V output
voltage pin,andall the buttonsforthe sensingpurpose are connectedtodigital inputforthe
code controllingthe whole vehicle.The PWMI/Opinwill be linkedtoall the motorsto give
pulse signalswithdesiredlengthforeachmotorrotation. All servomotorsshouldworkin
the range of pulse widthof (750us ~ 2250us2) and ArduinoMegacan provide these pulses
fromthe PWMoutput.
PulseMax= 16Mhz > PulseMotors
The currentcapacity onDC I/Opinis40mA, whichisinthe effective currentrange of the IR
receiverandthe buttons. We can test the currentvalue fromI/Opinof ArduinoMegausing
resistorandsome calculations.First,we connectresistoratI/Opin andMeasure voltage
across the resistorwithvoltage meter.Thenwe will be able tocalculate the currentcoming

8. 8
out fromthe Arduinousingthe followingequation.VR/R=I main= 40mA (with5% error,
Estimation) .
PMain = 20mA × 5V = 100mW
By using 9V battery which contains 550mAh
Max operating Hours: 550mA × 3600Sec / 100m = 19800sec = 5.5 hours
4.4.2 MotorModule
Continuous Motors
Fig. 3: Continuous Rotation Servo Motor
Two continuousrotationservomotorsare usedforthe vehicle mode, itwill simplyfunction
as wheels.The motorsare poweredupbythe 7.4V 2-cell lithiumbatteryandreceivethe
pulse signal fromArduinoMega.The pulse lengthforrotatingmotorsisdifferentfromthe
standardservomotor.It has three motions:turningclockwise,counterclockwise,andstop.
Each motionisdeterminedbyaspecificpulse length asshowninfig.4.

9. 9
Fig. 4: Continuous Servo Motor Pulses
Standard Servo Motors
Fig. 5: Standard Servo Motor
Eightservomotors are usedfor the quadpodmode. It'sposition isdeterminedbyaspecific
pulse length asshowninfig.6.

10. 10
Fig. 6: Standard Servo Motor Pulses
The motors are dividedintwogroups,one forthe X-axismovementandthe otherforthe Y-
axismovement;asfollows:
 StandardServoMotors (X-axis)
The 4 standard servomotorsare usedfor eachlegmovingx-axisforthe Quadpod
mode.The 7.4V 2-cell lithiumbatterypowersupthe motorswithvoltage regulator
for the inputvoltage forthe motors.The rotationangle of the standard servomotor
dependsonthe inputsignal pulse length,sentbyArduinoMega.The inputpulse
lengthisbetween750μsand 2250μs, whichis correspondingtothe whole 180°
angle movementof the motor.Thismotorneedrepeatedpulse signalsatleastevery
20ms or fasterto maintainitsposition.The degree from45°to 135° will be used.
The angle will be calculatedwiththe followingequation:
T (us)= 750us + {1500us (θ/180)} (45°< θ <135°)
 StandardServoMotors (Y-axis)
The other 4 standard servomotorsare used for eachlegmovingy-axisforthe
Quadpodmode.These y-axismotorsare responsible fortransformingbetweenthe
vehicle mode andthe Quadpodmode andthe y-axislegmoving.Specifically,whenit
transformsfromthe vehicle mode tothe Quadpodmode,the liftedlegswill be
broughtdownto the ground;the reverse transformationwill make the legstomove
the opposite way.The restspecificationsare the same asx-axisstandardservo
motorsexceptforthe degree range (0°< θ <180°)2).

11. 11
Fig. 7: Standard servo motor rotation degree
4.4.3 PowerModule
9V battery
One 9V batteris usedonlytopowerup the mainstationwhose recommendation
inputvoltage range is7~12V.
Main station power source: Voltage = 9V
Capacity = 550mAh
7.4V Lithium battery
Six lithium 7.4V Batteriespowerupthe servomotors.5V voltage regulatorisused
to make the voltage downto5V. Thisvoltage regulatorshouldbe capable toendure all of
the current flowtothe motors.
Servomotorspowersupply:
Voltage = 5V
Capacity =2000mAh
Max continuous current = 20A
Power consumption by one motor = 190mA
8*Imotor = 1.5A
4.4.4 Voltage Regulators
The inputvoltage tooperate the motorsis 4~6 VDC.The voltage regulatorsforeach
Lithiumbattery make the 7.4 voltsdown to 5 voltsforthe motors.
Input voltage: 7.4V
Max Input current: 190mA X 8 = 1.5A
Voltage regulator output voltage = 5V

12. 12
Voltage regulator max current output = 1.5A
4.4.5 IR receiver
Takesserial datafrom the remote transmitterandsendsittothe main station.The
original commendinside remotecontrollerwill notbe used.Instead,we will code ourown
commends. There are 7 differentcommendandeachwill be differentsignal sothatthe
signal will notmessedupwitheachother's.Thisdevice need2.5to 5.5V to powerup andit
needsatleast5mA source to activate.Since ourArduinoprovide 40mA with5V,it will be
reliable tofullyfunction.
let’sovervieweachof the componentsinthe IRControl Kit:
IR LED
Let’sstart withsimplestof the componentsfirst –the infraredLED. Anyone who’sever
workedwithelectronicshasblinkedan LED, butthose blinkingLEDsare usuallyinour visual
spectrum.These IRLEDs are justlike anyLED you’ve blinkedbefore,buttheyemitlightata
wavelengthof about 950nm – radiationwell outsideof ourvisual range (about390 to
700nm).
Fig. 8: IR LED
You can’t see these LEDslightup,but youcan still use themjustlike anyLED. Theystill have
twopolarized legs:ananode (positive,the longleg) andacathode.Theyhave a typical
forwardvoltage of about 1.5V, and a maximumforwardcurrentof 50mA.
330Ω Current Limiting Resistor
Justas withany LED, the IR LED needsa seriesresistortolimitcurrent.That’swhatthe
included 330Ω resistorsare for.

13. 13
Fig. 9: 330Ω Resistor
Witha 5V supplyconnectedtothe resistor/LEDseriescombo,currentthroughthe LED
shouldbe limitedtoabout10mA,whichiswell inside itssafe operatingrange.
TSOP38238 IR Receiver Module
While itmaylooklike a simple transistor,the TSOP38238 IR receivermodule isactuallya
unique,light-demodulatingintegratedcircuit.Withthree pins,it’saboutassimple asanIC
can get.There are two pinsforpower – ground inthe middle,andVS to a side – and one,
single dataoutputpin.
Fig. 10: TSOP38238 IR receiver
The IR receivercanbe poweredatanywhere from 2.5V to 5.5V, so itplaysverynicelywitha
varietyof developmentboards.

14. 14
Thismodule istunedto demodulate 38kHzsignals,which are a verycommoninthe IR signal
world.Itturns a spiky,modulatedsignallikethis:
Fig. 11: Modulated Signal
Intothisa cleaner,mucheasiertoreadsignal like this:
Fig. 12: Demodulated Signal
So all we have to do to readthe outputof this device iscounthighand low pulses,and
measure theirdurations.
IR Remote
Finallywe come tothe flashypart of the kit:SparkFun’scustom-made InfraredRemote
Control.This nine button remote emitsunique 32-bitcodesforeachbuttonpress.The codes
are mappedasshownon thisimage (thiswill come inhandyinourfirstexample):

15. 15
Fig. 13: Code Scheme for Remote
The remote’sinfraredoutputsignal ismodulatedat38kHz, soit worksperfectlywiththe IR
receivermodule.
4.4.6 Sensors
Bumper Sensor
Fig. 14: Sharp GP2Y0A21YK Sensor
We usedthe SharpIR Sensoras a bumpersensor, which isa distance measuringsensor
unit,composedof anintegratedcombinationof PSD(positionsensitivedetector) ,IRED
(infraredemittingdiode) andsignal processingcircuit.The varietyof the reflectivityof the
object,the environmental temperature andthe operatingdurationare notinfluencedeasily
to the distance detectionbecauseof adoptingthe triangulationmethod.

16. 16
The basisfor triangulationisthatobjectsatdifferentdistanceswill reflectthe infraredbeam
back to the receiveratdifferentangles.The varyinganglesproduce differentvoltage levels
inthe sensor,andinturn sensorvaluesthatcan be usedto calculate distance.See fig.4and
fig.5.
Fig. 15: Triangulation effect
Fig. 16: Triangulation effect

17. 17
4.4.7 Mechanical Design
The detaileddesignforthe mechanical partsisonthe Appendix B.
For the real model of the projectreferto AppendixC.

18. 18
Chapter Five: Results and Analysis
5.1: Centerof Mass
We estimatedthe weightof eachcomponentinourprojectandit isappearas
showninbelow:
Arduino =40gm
Each motor =44gm
Continuous motor =40gm
Total mass of motors=(8*44)+(2*40) =432gm
Weight With battery and without arduino and without frame well be 553g
Weight With battery and with arduino and without frame well be 593g
We reachedtoa conclusionthatthere's twotechniquestofindthe centerof mass , one is
theoretical andthe otheris practical.Andthey're discussedbelow:
 Theoretically:
To findthe centerof mass to thisrobot , we will use the followingequation:
𝒙 =
∑𝐦𝐢∗ 𝐱𝐢
∑𝐦𝐢
x:Centerof mass.
xi:the x-axiscoordinates.
mi:componentsmass.
Fig. 17: Center of Mass Concept
 Practically

19. 19
The experimental determination of the center of mass of a body uses gravity forces on
the body and relies on the fact that in the parallel gravity field near the surface of the
earth the center of mass is the same as the center of gravity.
The center of mass of a body with an axis of symmetry and constant density must lie on
this axis. Thus, the center of mass of a circular cylinder of constant density has its center
of mass on the axis of the cylinder. In the same way, the center of mass of a spherically
symmetric body of constant density is at the center of the sphere. In general, for any
symmetry of a body, its center of mass will be a fixed point of that symmetry
Fig. 18: Center of Mass
5.2: ComponentsTest
5.2.1 IR receiver Test:
We testedthe IR kitusingthe arduinomegaand the example code inthe kitguide
and connecteditas showninFig.19.For the code refertoAppendix G.1 andAppendix E.
Fig. 19: Connection of IR

20. 20
For our project,we builtourowncode for the IR kitas showninAppendix G.2. Andwe got
the followingresultwhenwe testedthe code.
Fig. 20: Results of the code test
5.2.2 Motors Test :
5.2.2.1 Continuous Rotation Motor Test
We testedthe motorusingthe arduinomegaandthe example code inthe guide and
connecteditas showninFig.21. Forthe code referto AppendixG.3and AppendixE.
Fig. 21: Connection of motor

21. 21
5.2.2.2 Standard Servo Motor Test
We testedthe motorusingthe arduinomegaandthe example code inthe guide and
connecteditas showninFig.22. Forthe code referto AppendixG.4.
Fig. 22: Connection of motor
5.2.3 Bumper Sensor Test :
We testedthe sensorusingthe arduinomegaandthe example code inthe guide and
connecteditas showninFig.23. Forthe code referto AppendixG.6.
Fig. 23: Connection of sensor

22. 22
Chapter Six: Discussion
In our project,We supposedthatthe robotwill move legafterleg,butwe have foundedthat
our propositionleadsto unbalancedsituation cause of the change inthe centerof mass, so
we have searchedabout somethingmore reliable andacceptable whichwas gettingan
obstacle connectedtoa motorthat move inthe opposite wayof the usedmotorandwhen
the device isstandingthisobstacle isatthe centerof masswhichwe assume itto be at the
middle of the robot.
As forthe sensorat first, we thoughtthat "The Proximity TouchSensor"will be agood
choice butafter that we decidedtouse "The SharpIR Sensor"whichdetectthe obstacle
froma distance of 10 to 80 cm accordingto the data sheetwhichismore reliable.
Afterthe componentstest,we connectedthe componentstogethertogetthe final formof
the projectas showninAppendix C.
Thenwe wrote the final code of the project(showninAppendix G.5) ,andwhenwe sentitto
the arduinowe got some errorsin the angle of the legmotorsso we usedtrial and error
alongwithpreviousprojectsexamplefromthe netlike spiderrobottoget the right angles
for the legmovements.

23. 23
Chapter Seven : Conclusionand Recommendation
Throughour workoverthe course of semester,we have successfully designedthe
schematicof a vehicle thatcan transformintoquadpod. The projectwe designed isfully
controllable byuserinbothquadpodmode and vehicle mode. Usercan control the
movementof the projectusingthe IRremote controller. The projectalsohas obstacle
sensor that automaticallydetectsobstacle sendssignal totransformthe vehicleto
Quadpod.
Many of the uncertaintiescome frommechanical issuessuchasframe design,durability,and
weight.Asourstudiesleadusthatif the projectdoesn'thave frame workthat fixesthe leg
to the side of the body while it'sinvehiclemode,the quadpodlegshave tobe fixedat90
degpositionbygivingthe pulse signal toavoidittouchingthe floor.Thisnotonlytakes
unnecessaryspace,butitalsoconsumesextraenergythatcouldotherwisebe conserved.In
orderto have more efficientframe design,we wouldneedlargerbodyframe andadditional
frame that wouldfix the legsincertainpositionwhile it'sinvehiclemode.However,larger
bodyframe wouldcause the durability of frame todecrease whileincreasingthe weightof
the project.
As we have mentionedinchallenges,one of the mainissue we have toimprove forfuture
workis frame design. Ourcurrentframe designisinefficientinbothspace andpower
consumption. Bycreatingframe designthatholdsthe positionof the legswhile the project
isin vehicle mode,itwill save bothspace andpowerconsumption.Improvedframe design
will probablyincreasethe weightof the project. Sowe needtopay attentiontothe servo
workingtorque accordingtothe weight.
We are tryingto create newtype of vehicle withsimpledesigninregardsof the practical
usage.We are opento accept anyhonestcriticismregardingtechnical issuesbyadmitting
our lackof knowledge forbetter andpractical designandtechnical work.Aswe use some
parts that are alreadymade by a company,we mustgive a full credittothe companyby
mentioningtheirname andworkinpropermanner.