Light Guided Path Tracker Robot

i

LIGHT GUIDED PATH TRACKER ROBOT

HUZAIFA BIN MUSA

This Report is submitted in Partial Fulfillment of Requirements for the Degree of Bachelor in Mechatronic Engineering

FACULTY OF ELECTRICAL ENGINEERING UNIVERSITI TEKNIKAL MALAYSIA MELAKA

ii

ACKNOWLEDGEMENT

In The Name of Allah the Most Merciful and Most Compassionate

There are many individuals that had contributed to the success of this Final Year Project

(FYP). First and foremost, our gratitude goes to Al-Mighty for bestowing the strength and

patience in completing this report. My warmest gratitude goes to my supervisor, Mr. Prof.

Madya Dr. Ismadi bin Bugis for giving the most beneficial guidance and assistance to me in

finishing my FYP.

My in most appreciation goes to Mr. Mohd Shahrieel bin Mohd Aras, Mr. Hyreil Anuar bin

Kasdirin and Mr. Zamani bin Md Sani for giving me a good comments and developing critics

during FYP seminar.

Last but not least, I would like to express my deepest gratitude to my beloved mother and

father, as well as our family members and everyone who has involved directly or indirectly for

their moral support and understanding. It‟s not an easy way to me for survive without their

helping.

iii

ABSTRACT

This project basically is to build a mobile robot that is able to sense light and move

toward the light source as an attraction of a robot. At the end of this project, a Light Guided

Path Tracker Robot was build. The robot is operated without using any external controller to

control a movement of the robot. Cadmium Sulfide (CdS) photocells are used as a sensors for

the robot that will detect the light source and controlled by PIC 16F877A as a controller. The

sensor acts as radar to detect light illuminating from surrounding and will produce a certain

differential potential. These potential differentials which is an analog signal processed by a

microcontroller as a digital value, and a microcontroller will sending an instruction to the

iv

ABSTRAK

Projek ini pada asasnya adalah untuk membina sebuah robot mobil yang berkebolehan

untuk mengesan cahaya dan akan bergerak ke arah sumber cahaya tersebut. Projek ini akan

menghasilkan sebuah robot pintar dengan nama yang diberikan sebagai Light Guided Path

Tracker Robot. Robot ini akan dikendalikan tanpa mengunakan sebarang alat kawalan luar

untuk mengawal arah pergerakannya. Perintang peka cahaya (CdS photocell ) akan digunakan

sebagai deria kepada robot yang akan mengesan cahaya dan akan dikawal dengan

menggunakan pengawal mikro PIC 16F877A. Tindak balas yang diberikan oleh perintang

peka cahaya terhadap pencahayaan sekeliling akan menghasilkan satu bezaupaya yang

tertentu. Bezaupaya tersebut seterusnya akan diproses oleh pengawal micro sebagai suatu nilai

digital seterusnya menghantar arahan ke bahagian litar keluaran yang terdiri daripada system

v

“I hereby declared that I have read through this report entitle “Light Guided Path Tracker

Robot” and found that it has comply the partial fulfillment for awarding the degree of

Bachelor of Mechatronic Engineering”

Signature : ……….

Supervisor‟s Name : Prof. Madya Dr. Ismadi bin Bugis

vi

“I hereby declared that this report entitle “Light Guided Path Tracker Robot” is the

result of my own research except as cited in the references. The report has not been

accepted for any degree and is not concurrently submitted in candidature of any other

degree.”

Signature : ………

Name : Huzaifa bin Musa

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

ACKNOWLEDMENT ii

ABSTRACT iii

DECLARATION v

TABLE OF CONTENTS vii

LIST OF TABLE x

LIST OF FIGURES xi

LIST OF SYMBOLS xiii

LIST OF APPENDICES xiv

1 INTRODUCTION 1

1.1 Project Background 1

1.2 Problem Statement 2

1.3 Objective of Project 2

1.4 Scope of Project 3

2 LITERATURE REVIEW 4

2.1 Literature 1 : Autonomous Light Finder Robot 4

2.2 Literature 2 : Light Rover 6

2.3 Literature 3 : Veroboard Bot 8

2.4 Literature 4 : Light Seeking Robot 10

2.5 Literature 5 : Robot Mobil Pengesan Cahaya 11

3 THEORY AND BACKGROUND 12

3.1 PIC Microcontroller 12

3.2 Light Sensor 15

3.3 DC Motor 20

3.3.1 Operating Voltage of DC Motor 21

3.3.2 Operating Current of DC Motor 21

3.3.3 Speed of DC Motor 23

viii

3.3.5 Power of DC Motor 23

3.3.6 Gear and Speed 24

3.4 H-Bridge Circuit (L298) 24

3.5 Pulse Width Modulation in Microcontroller 26

4 METHODOLOGY 28

4.1 Overview of the Project Development 28

4.2 Designing a Light Guided Path Tracker Robot 32

4.3 Software Implementation 34

4.3.1 Algorithm and Programming in MicroC 34

4.3.1.1 Processing Explanation of Main Program 36

4.4 Research Methodology 41

4.4.1 Selecting the Fixed Resistor ( Rf ) Value for Light

Sensing Circuit. 41

4.4.2 Controlling the Speed of Robot Based on the

Intensity of Light 44

4.4.3 Evaluate the DC Motor Performance on L298 Dual

H-Bridge Driver 48

5 RESULT, ANALYSIS AND DISCUSSION 52

5.1 Introduction 52

5.2 Experiment 1 : Selecting the fixed resistor for light sensing circuit

52

5.2.1 Objective 52

5.2.2 Equipment Required 52

5.2.3 Procedures 53

5.2.4 Result and Discussion 55

5.2.5 Conclusion 59

5.3 Experiment 2 : Controlling the speed of robot based on the intensity of light

60

5.3.1 Objective 60

5.3.2 Equipment Required 60

5.3.3 Procedures 60

5.3.4 Result and Discussion 62

5.3.5 Conclusion 64

5.4 Experiment 3 : Evaluate the performance of DC motor on L298 dual H-bridge driver

ix

5.4.1 Objective 65

5.4.2 Equipment Required 65

5.4.3 Procedures 65

5.4.4 Result and Discussion 67

5.4.5 Conclusion 72

6 CONCLUSION AND RECOMENDATION 73

5.1 Conclusion 73

5.2 Recommendation 74

REFERENCES 75

x

LIST OF TABLES

CHAPTER TABLE PAGE

3 Table 3.1 : Truth Table for Controlling DC Motor 26

4 Table 4.1 : Resistance in the shade (R_dark) and Resistance

in the (R_bright)

42

Table 4.2 : Comparison Between Theoretical Output Voltage and Real Time Measurement Output Voltage

43

Table 4.3 : Comparison Between Light Intensity Value and Speed

47

Table 4.4 : Voltage Comparison Between Left Motor and Right Motor

49

Table 4.5 : Current Comparison Between Left Motor and Right Motor

51

5 Table 5.1 : Comparison Between Resistance in the Shade and

Resistance When Exposed Directly to the Light

55

Table 5.2 : Light Sensing Circuit Measurement Result 56

Table 5.3 : Average Resistance Value in Dark and When Exposed Directly to Light

57

Table 5.4 : Comparison Between Resistor Value and Voltage Output

57

Table 5.5 : Comparison Between Theoretical Result and Real Time Measurement Result

58

Table 5.6 : Comparison Between Light Intensity Value and Speed

62

Table 5.7 : Connection for Microcontroller and L298 66

Table 5.8 : Voltage Measurement Result 67

xi

LIST OF FIGURES

CHAPTER FIGURE PAGE

2 Figure 2.1 : The Autonomous Light Finder Robot 5

Figure 2.2 : Light Rover 6

Figure 2.3 : Differential Steering 9

3 Figure 3.1 : PIC16F877A Microcontroller Pin Configuration 13

Figure 3.2 : Photoresistor or Light Dependent Resistor (LDR) Picture

15

Figure 3.3 : The Cadmium Sulphide Track of Photoresistor 16

Figure 3.4 : The Voltage Divider Circuit 16

Figure 3.5 : Voltage Increases With Light Circuit 17

Figure 3.6 : Voltage Decreases With Light Circuit 18

Figure 3.7 : Light Sensing Circuit for One Sensor 18

Figure 3.8 : Small DC Geared Motor 20

Figure 3.9 : Model of Simple DC Motor 21

Figure 3.10 : Bi-Direction of DC Motor Speed Control 25

4 Figure 4.1 : Simulation Process by Using Proteus 7.2 Software 29

Figure 4.2 : MicroC V8.1 30

Figure 4.3 : PIC Programmer Hardware 31

Figure 4.4 : Sample Robot Design by Using SolidWork 2007 Software

32

Figure 4.5 : Light Guided Path Tracker Robot 33

Figure 4.6 : Arrangement of the Sensors for the Robot 34

Figure 4.7 : Flowchart of Microcontroller Main Program 35

Figure 4.8 : Result of A/D Conversion in Two A/D Registers 36

Figure 4.9 : The ADCON1 Register 37

Figure 4.10 : The A/D Port Configuration Bits 37

Figure 4.11 : PWM Output 38

Figure 4.12 : Simplified Block Diagram of the CCP Module in PWM Mode

39

xii

Figure 4.14 : Simulation Diagram 45

Figure 4.15 : Experiment Setup Diagram 46

Figure 4.16 : Motor Driver Board Layout 48

5 Figure 5.1 : Measuring the Resistance of Photoresistor by

Using a Multi-meter

53

Figure 5.2 : Light Sensing Test Circuit 54

Figure 5.3 : Graph Theoretical Output Voltage Versus Measurement Output Voltage

59

Figure 5.4 : Line Marking Setup 60

Figure 5.5 : Graph Light Intensity Versus Distance of the Light Source

63

Figure 5.6 : Graph Light Intensity Versus Speed 63

Figure 5.7 : DC Motor Test Coding 65

Figure 5.8 : Output Voltage Versus CCP1 ( PWM1) 69

Figure 5.9 : Output Voltage Versus CCP2 ( PWM2) 69

Figure 5.10 : L298 Block Diagram and Red Box Show the BJT Inside the L298

xiii

LIST OF SYMBOLS

- Magnetic Flux

- Armature Current

- Voltage Output

- Armature Resistor

- Electro Magnetic Field (EMF)

K - Motor Constant

n - Rotational Speed (rpm)

- Motor Speed

- Total Voltage

- Electrical Output Torque

D - Duty Ratio

- Time ON switch

- Frequency

- Voltage Input

- Output Power

- Fixed Resistor

rpm - Revolution Per Minutes

PWM - Pulse Width Modulation

LDR - Light Dependent Resistor

xiv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A PIC Instruction Set For Experiment 2 : Controlling the

speed of robot based on the intensity of light

76

B Full Instruction Set of Light Guided Path Tracker Robot 78

C Light Guided Path Tracker Robot Design By Using

Solidwork 2008

80

CHAPTER 1

INTRODUCTION

In this section, an introduction towards project will be briefed. This chapter consists of

background, problem statement and scope of the project.

1.1 Project Background

Light Guided Path Tracker Robot is a mobile robot that similar with Light Seeking

Robot, Light Finding Robot, Light Sensing Robot, Light Chasing Robot, Light Tracking

Robot and Light Following Robot. As the name suggests, it able to directs itself towards the

visible light as an attraction point. A user can direct shine flashlight to robot sensors and as a

respond, the robot will follow the source of light. Its speed is dependent upon the intensity of

the light detected. The higher intensity of the light, the faster movement of the robot. To

accomplish this project, it is divided on three parts which are mechanical part, electronic part

and software part.

In the mechanical part, the base of the mobile robot will be designed and fabricated. In

the electrical part, there are three different circuit need to design and construct which are light

sensing circuit, PIC microcontroller board and motor controller circuit. For software part, the

2

1.2 Problem Statement

Most of the light sensing robot that has already built can only functioning well at dark

environment. Some robot is designed with 3 sensors, a center, a left and a right. And some

other are designed with 2 sensors, a left and a right. The movement of a robot created is also

limited because the robot can only move forward, turn right and turn left, and the robot do not

have ability to go backward, reverse left and reversed right. Some robot does no use

microcontroller as its mind and the robot speed cannot be controlled.

The purpose of this project is to overcome all the problems faced on the light sensing

robot that had been mentioned previously.

1.3 Objective of Project

The main objective of this project is to build the robot that is able to sense and follow

the visible light by using PIC microcontroller as the main controller. To ensure the project

progresses smoothly, there are some objectives that need to be achieved:

a) To do simulation and build the electronic circuit.

b) To design and establish the mechanical structure of robot.

c) To achieve multi direction motion.

d) To control the speed of robot by using the intensity of the light.

e) To measure the resistance value of Light Dependent Resistor (LDR) when the LDR is

exposed to the light and direction of the robot will be determined from resultant of the

3

1.4 Scope of Project

To understand the function of components for the robot, there are some theories about

project background research and literature review that must be studied. The components such

as PIC microcontroller, light dependent resistor (LDR) sensor and motor will be considered as

main component in this project. Light Guided Path Tracker Robot uses a microcontroller for

processing the sensor readings and responds by controlling the motors. The microcontroller

that will be used in this project is PIC 16F877A, this is due to its internal ADC which is

important in converting the analog signal from the light dependent resistor (LDR) sensor to

digital signal that can be read by the microcontroller. There are some software will be

implemented in this project which include :

a) MicroC – used for compiling the hex file to PIC

b) Proteus – used for simulation of PIC and PCB layout design

CHAPTER 2

LITERATURE REVIEW

To have a brief understanding of the researches related to the project, a few literature

reviews had been done. This chapter will describe the related literature reviews.

2.1 Literature 1

Title : Autonomous Light Finder Robot

Author : Katja and Guido Socher July 30, 2006 [1]

Institute : University of Pittsburgh, Pittsburgh, Pennsylvania, United States.

Autonomous Light Finder Robot is an autonomous robot controlled by an AVR

microcontroller. As its name suggests, the robot has been programmed to run towards the

brightest spot in the room. The robot has only 2 wheels which are driven by 2 independent

motors. The independent motors used are the 2 small gear-box motors. The third wheel is a

ping-pong ball. This enables the robot to turn on the spot.

The robot uses an AT90S4433 as its controller. For an autonomous robot it is

obviously important that it can operate from batteries. Since the microcontroller runs with

4.5V, the motors also must work with 3-5V. The motors also not take too much current

otherwise the batteries and the control circuit will get too big and heavy. For this design, the

robots use an integrated motor driver chip, called L293D. This chip contains 4 digital output

amplifier stages with extra protection diodes to protect against high voltages induced by the

coils of a motor. Two of the output stages can be used to drive one motor. This way it is

5

The Autonomous Light Finder Robot uses two types of sensor, which are touch sensors

and light sensors. The touch sensors are simple switches made out of steel wire. The light

sensors are 3 photo resistors and the card board is placed between the photo resistors. This

card board creates shadows on the resistors when the light comes from the side. Only when the

light comes exactly from the top it will provide for an equal amount of light on all 3 sensors.

Comparing the values of the 3 sensors the robot can decide in which direction to go. Based on

the comparison of the photo sensors, the robot can then decide which motor to turn. Since the

robot have only 2 wheels , so the robot can turn its self on the spot by turning one of the

wheels faster or even turning them in opposite direction.

6

2.2 Literature 2

Title : Light Rover

Author : Thientu Ho and David Shu April 22, 2005 [2]

Institute : Cornell University,Ithaca, New York, United Stated.

Light Rover is a robot that can sense and follow light. A user can shine a flashlight at

its front and Light Rover will respond by following the light source. Its speed is dependent

upon the intensity of the light detected. Light Rover uses a microcontroller for processing the

sensor readings and responds by controlling the motors.

7

Light Rover is designed with two sensors in mind, a left and a right. When more light

is detected on the left side, the robot will move towards it by rotating the right motor forward

and the left motor backwards. The robot will know to move forward when both sensors

received about the same amount of light. The robot is only designed to respond to visible light.

The robot uses two (2) bipolar stepper motor as a wheel and based on it, a major

hardware design task in this project was to drive the bi-polar motors. These motors have no

center taps on their windings. Therefore, to reverse the direction of the magnetic field

produced by a coil, the current through the winding need to reverse by using the H-bridge

stepper motor control circuit.

The controller uses is Atmel MEGA32 microcontroller. The sensors uses for the light

rover are 2 CDS-T08 photocell sensors. The light sensing circuit consists of two photocells

mounted on either side of the vehicle. The photocell produces a variable resistance based on

light intensity.

8

2.3 Literature 3

Title : Veroboard Bot

Author : Jd Stufu, March 30, 2005 [3]

Institute : University of Valladolid, Valladolid, Spain

Veroboard Bot is a light sensing robot that can move towards a bright light source. The

robot has the ability to avoid obstacles while seeking for the location in its environment that

has the greatest amount of light. The Veroboard Bot uses PIC16F84A microcontroller as a

controller.

Veroboard Bot is a differential drive photophile robot with tactile sensor. Photophile

means that the robot will seek for the location with the greatest amount of light. It does this

through the use of its two light dependent resistor (LDR) sensors. The LDR changes in

resistance with respect to the amount of light expose to it. Its resistance is near infinity in

absolute darkness and near zero when in bright light. The Veroboard Bots have two LDR

sensors located in front of its, one on the left and one on the right.

Differential drive means it uses two DC motors for steering. Both motors turn on at the

same speed but opposite rotation (right motor clock wise and left motor counter clock wise) to

move the robot forward. To turn left, left motor if turned off while right motor turns on in

clockwise rotation. To turn right the left motor is turned on in counter clockwise rotation while

the right motor is turned off. To move backwards, the motors should both turn on at the same

speed but opposite their direction of rotation is in opposite to the rotation of direction while

moving forward. The direction of rotation of the DC motor shaft is dependent on the polarity

of supply voltage applied to its terminal. Changing the polarity of the supply voltage changes

the direction of rotation of the DC motor shaft. Changing the polarity of the supply voltage

can be done by a solid state switch in H-bridge configuration. These solid state switches are

already integrated inside a chip called L293. The L293 has 4 inputs that directly controls the 2

9

10

2.4 Literature 4

Title : Light Seeking Robot

Author : Nicholas David Densley May 6, 2001 [4]

Institute : Sheffield Hallam University , South Yorkshire , England

This project is aimed at looking into the coding required for a light seeking robot. The

rational for this is to look into what AI programming techniques can be used to enable a robot

to cope with a dynamic environment. A dynamic environment is an area that is not clear of

obstacles and the robot must be able to navigate them in an appropriate manner whilst taking

into account its own power considerations.

This project aims to produce a small light seeking robot to demonstrate some of the

coding produced. To control the robot an embedded PIC16F877 chip is to be used. The base of

the robot is simply two bi-directional dc motors in a plastic casing. An L293N driver chip has

been selected, this chip is capable of supplying a constant 1A per channel, to two