Fyp Thesis sem

DESIGN AND DEVELOPMENT OF A PIPE INSPECTION

ROBOT

MUHAMMAD AZRI BIN ABDUL WAHED

UNIVERSITI SAINS MALAYSIA

2015

DESIGN AND DEVELOPMENT OF A PIPE INSPECTION

ROBOT

by

MUHAMMAD AZRI BIN ABDUL WAHED

Thesis submitted in partial fulfillment of the

requirements for the degree of

Bachelor of Engineering (Electronic Engineering)

JUNE 2015

ii

ACKNOWLEDGEMENTS

I am grateful to God for the good health and wellbeing that were necessary to

complete this final year project. There are many people that deserve mentions and

thankfulness for their help, guidance and support during the duration of this project. It is

impossible for me to complete this dissertation without them.

I wish to express my sincere thanks to my final year project supervisor, Prof. Dr

Mohd Rizal Arshad, Deputy Dean of School of Electrical and Electronic Engineering

USM for providing me with all the necessary means and facilities to complete my project.

Dr. Rizal had provide me with a clear concept on my project which leads to the

successfulness of my project. His patience in guiding me to come out with a good thesis

is very much appreciated.

Besides, my sincere thank you to Mr. Muhammad Faiz bin Abu Bakar, Research

Assistant for Underwater, Control, and Robotics Group (UCRG). He had provide me

with assistant throughout the duration of this project. He had assisted me in developing

the graphical user interface for my final year project. Mr .Faiz also contributed a lot

during the testing of my project.

Many thanks go to Mr. Hafiez Mokhtar and Mr. Muhammad Azwan. Mr. Hafiez

had helped me in resourcing of material and checking of my design while Mr. Azwan

had helped me in understanding the theory for the embedded system development.

I would also like to take this opportunity to express gratitude to all the member

of Underwater Robotics Research Group for their help and support. I also thank my

parent for the unlimited encouragement, support and attention.

Last but not least, my sense of gratitude to one and all, who directly or indirectly,

have lent their hand in this project.

iii

TABLE OF CONTENTS

Acknowledgements ii

Table of Contents iii

List of Tables vii

List of Figures viii

List of Abbreviations xii

Abstrak xiii

Abstract xiv

CHAPTER 1 - INTRODUCTION 1

1.1 Background 1

1.2 Motivations 2

1.3 Problem Statements 3

1.4 Objectives 3

1.5 Scope 4

1.6 Outlines of Report 4

CHAPTER 2 – LITERATURE REVIEW 6

2.1 Introduction 6

2.2 Wheel type 7

2.2.1 Direct drive 7

2.2.2 Differential drive 7

2.2.3 Tractive vehicles 8

2.3 Caterpillar type 8

2.3.1 LS-01 9

iv

2.4 Wall-press type 9

2.4.1 MRINSPECT III 10

2.4.2 MRINSPECT IV 10

2.5 Walking type 11

2.6 Inchworm type 12

2.6.1 MARK IV 12

2.6.2 Pneumatic line based inchworm type 13

2.7 Screw type 14

2.8 Electro-magnetic force type 15

2.9 Comparison of pipe inspection robots 15

2.10 Components required 16

2.11 Summary 17

CHAPTER 3 - METHODOLOGY 18

3.1 Introduction 18

3.2 Flow Chart 18

3.3 Design Specification 20

3.4 Project Requirements Selections 22

3.4.1 Arduino Micro ATmega32u4 22

3.4.2 Motor Driver 23

3.4.2.1 L293D and 74HC595 23

3.4.3 DC Micro Metal Gear Motor 45 rpm 25

3.4.4 DC Geared Motor SPG30-60K 26

3.4.5 Micro Servo Motor MG90s 26

3.4.6 Camera JK-801 27

3.5 Mechanical System Development 28

v

3.5.1 3D Modeling Using SolidWorks 28

3.5.2 Fabrication 32

3.5.2(a) Camera Enclosure 34

3.5.2(b) Driving Module 35

3.5.2(c) Electronic Compartment 36

3.6 Embedded System Development 38

3.6.1 Driving Module 39

3.6.2 Camera Pan and Tilt 44

3.6.3 Graphical User Interface 46

3.7 Testing 49

3.7.1 Drivability Test 49

3.7.2 Camera viewing Vision 52

3.8 Performance Evaluation 52

3.9 Summary 52

CHAPTER 4 – RESULTs AND DISCUSSIONs 53

4.1 Introduction 53

4.2 Result of Mechanical System Development 53

4.3 Result of Embedded System Development 56

4.3.1 Driving Module 57

4.3.2 Camera Pan and Tilt 57

4.3.3 Graphical User Interface 59

4.4 Testing Results 60

4.4.1 Drivability Result 60

4.4.2 Camera Viewing Vision 65

4.5 Real Time Performance Evaluation 66

vi

4.7 Summary 68

CHAPTER 5 – CONCLUSION & FUTURE WORK 69

5.1 Conclusion 69

5.2 Future Works 70

REFERENCES 71

vii

LIST OF TABLES

Page

Table 2.1 Comparison between pipe inspection robots 16

Table 2.2 Components function 17

Table 3.1 Desired robot specifications 20

Table 3.2 Dimension of pipe inspection robot 21

Table 3.3 Truth table for each driver 24

Table 4.1 Speed of pipe inspection robot for various slope angle 60

Table 4.2 Motor force and motor torque required for slope more than

30 degrees to achieve equilibrium

64

viii

LIST OF FIGURES

Page

Figure 2.1 Classification of pipe inspection robots

(a) Pig type

(b) Wheel type

(c) Caterpillar type

(d) Wall-press type

(e) Walking type

(f) Inchworm type

(g) Screw type

6

Figure 2.2 Wheels independently connected to motor 7

Figure 2.3 Differential drive 7

Figure 2.4 Plain structures of tractive vehicles 8

Figure 2.5 LS-01 prototype model 9

Figure 2.6 MRINSPECT III 10

Figure 2.7 MRINSPECT IV 11

Figure 2.8 Tube-crawler 12

Figure 2.9 MARK IV basic structure 12

Figure 2.10 Pneumatic inchworm working principle 13

Figure 2.11 Screw principle robot design 14

Figure 3.1 Research methodology flow chart 19

Figure 3.2 Arduino Micro Atmega32u4 front view 23

Figure 3.3 L293D block diagram 24

Figure 3.4 L293D pin configuration 25

ix

Figure 3.5 74HC595 pin configuration 25

Figure 3.6 DC micro metal gear motor 26

Figure 3.7 SPG30-60K 26

Figure 3.8 Micro servo motor MG90s 27

Figure 3.9 Mini CMOS CCTV camera JK-801 27

Figure 3.10 Schematic drawing of the total length of the robot 28

Figure 3.11 Schematic drawing of the maximum robot diameter 29

Figure 3.12 Schematic drawing for the front section 29

Figure 3.13 Schematic drawing for the driving module 30

Figure 3.14 Schematic drawing for the camera pan and tilt mechanism 30

Figure 3.15 Schematic drawing for the universal joint 31

Figure 3.16 External frame drawing 32

Figure 3.17 Internal frame drawing 33

Figure 3.18 Driving module 33

Figure 3.19 Base top view 34

Figure 3.20 Cage top view 34

Figure 3.21 Assembly of camera and servo motors 35

Figure 3.22 Driving module arm 36

Figure 3.23 DC motor inside electronic compartment 37

Figure 3.24 Threaded rod for expansion and contraction 37

Figure 3.25 Block diagram for embedded system 38

Figure 3.26 Connection between shift register and motor driver for front

driving module

39

Figure 3.27 Connection between shift register and motor driver for back

driving module

40

x

Figure 3.28 Connection from shift register to Arduino 41

Figure 3.29 Flow chart of programming code for receiving serial data

from PC and transmitting it to motor driver

42

Figure 3.30 Circuit constructed on strip board 43

Figure 3.31 LM2596 switching voltage regulator 43

Figure 3.32 Various PWM duty cycle 44

Figure 3.33 Connection between Arduino and micro servo motor 45

Figure 3.34 Flow chart for servo programming 46

Figure 3.35 Layout of the graphical user interface 47

Figure 3.36 Flow chart for graphical user interface 48

Figure 3.37 Setting up of testing ground 50

Figure 3.38 Angle calibration with smartphone level balance 51

Figure 4.1 Completed pipe inspection robot 54

Figure 4.2 (a) Top view

(b) Side vied

(c) Process of inserting the electronics into the electronic

compartment

55

Figure 4.3 (a) Long threads used to combine driving module with

electronics compartment

(b) screw used to hold motor in place

55

Figure 4.4 (a) Wiring from front to back section

(b) Motor wiring passing through a tube

(c) Power and signal wire wrapped with cable wrapper

56

Figure 4.5 (a) Camera view rotated 90° to the left

(b) Camera view at 0°

58

xi

(c) Camera view rotated 90° to the right

Figure 4.6 (a) Camera rotated 90° upwards

(b) Camera at horizontal position

(c) Camera at rotated 90° downwards

59

Figure 4.7 Graph of speed (m/s) against slope angle, Ɵ (°) with 100%

duty cycle

61

Figure 4.8 Pipe inspection robot successfully climbing inside the pipe

at 10° gradient

62

Figure 4.9 Position of robot at Ɵ degree angle

63

Figure 4.10 Comparison of the ambient light without and with the usage

of LED

65

Figure 4.11 Comparison of the actual images taken by the CCTV

camera without and with the usage of LED

66

Figure 4.12 Servo maximum angle rotation 66

Figure 4.13 (a) Robot starting at one end of the pipe

(b) Robot end at the other end of the pipe

67

Figure 4.14 (a) Robot in a smaller diameter configuration

(b) Robot in larger diameter configuration

67

xii

LIST OF ABBREVIATION

ABS Acrylonitrile Butadiene Styrene

CAD Computer-aided design

CCTV Closed-circuit Television

CMOS Complementary Metal-oxide-semiconductor

DAUJ Double Active Universal Joint

DC Direct Current

DOF Degree of Freedom

GUI Graphical Image Processing

IC Integrated Circuit

ICSP In-Circuit Serial Programming

LED Light Emitting Diode

LSB Least Significant Bit

MSB Most Significant Bit

PC Personal Computer

PLA Polylactic Acid

PVC Polyvinyl Chloride

PWM Pulse Width Modulation

SMA Shape Memory Alloy

STL Stereolithographgy

USB Universal Serial Bus

VCC IC Power Supply Pin

Vdc Volts of Direct Current

xiii

Rekabentuk dan Pembangunan Robot Pemeriksaan Paip

ABSTRAK

Robot pemeriksaan paip adalah sebuah kenderaan yang membuat pemantauan

keadaan dinding bahagian dalam paip. Robot pemeriksaan paip boleh dibahagikan

kepada tujuh jenis robot. Dalam projek ini, sejenis platform robot iaitu jenis penekanan

terhadap dinding telah difabrikasikan. Ianya mempunyai tiga bahagian berukuran 542

mm panjang dan 230 mm diameter maksima. Ianya mempunyai tiga bahagian untuk

meningkatkan kestabilan ketika pergerakan dan untuk memudahkan proses pemasangan

dan pembongkaran robot kembali. Robot jenis penekanan terhadap dinding dipilih

kerana ianya membolehkan robot mempelbagai diameter maksimanya. Tiga bahagian

robot adalah bahagian kamera, bahagian modul pacuan ke depan dan bahagian modul

pacuan ke belakang. Bahagian kamera terletak di bahagian depan sekali robot agar dapat

mengambil gambar yang jelas ketika di dalam paip. Bahagian pemanduan di reka supaya

terbahagi kepada dua adalah untuk melepaskan robot daripada sebarang rintangan di

dalam paip. Mikropengawal dan antara muka unit grafik digunakan untuk mengawal

robot ini. Ada sepuluh penggerak dan satu kamera dalam membangunkan sistem

terbenam robot ini. Penggerak tersebut adalah motor DC mikro logam dengan transmisi,

motor DC dengan transmisi dan motor servo mikro. Ujian bagi robot telah dijalankan di

makmal. Paip telah disusun supaya menyondong pelbagai darjah, dan darjah maksima

adalah 30 darjah untuk robot masih berupaya bergerak ke hadapan. Robot hanya mampu

untuk pusing ke kanan atau ke kiri apabila berada di luar paip sahaja. Secara

keseluruhannya, reka bentuk dan pembangunan robot pemeriksaan paip telah berjaya

apabila ia dapat bergerak dan memberikan visual dari dalam paip. Namun begitu, sistem

robot perlulah di tambah baik dengan penambahan penderia untuk mengesan diameter

paip maksima.

xiv

Design and Development of a Pipe Inspection Robot

ABSTRACT

Pipe inspection robot are vehicles that perform the monitoring of inner pipe

conditions. Pipe inspection robot mainly can be divided into seven types of robot. In this

project, a wall-press type platform is fabricated. It has three sections measuring a total

length of 542 mm and 230 mm maximum diameter. The three sections is to provide

sufficient stability to move and for easy disassembly and assembly. Wall-press type is

chosen because it provides the robot with an ability to vary its maximum diameter. The

three sections are camera section, front driving module section and back driving module

section. The camera is located at the front to provide a clear image inside the pipe. The

driving module section designed to be two sections is to allow the robot to get through

obstacles inside the pipe. Microcontroller and GUI is used to operate this robot. Ten

actuators and one camera are used to develop this robot embedded system. The actuators

are DC micro metal geared motor, DC motor and micro servo motor. Testing of the robot

is done in a lab. Pipe is configured for varying slope angle. For slope angle configuration,

the maximum angle that the robot are able to moves forward are 30°. The robot is able

to turn sideways while being outside of the pipe. Overall, the pipe inspection robot is

successfully designed and developed because it can navigate and provide view inside a

pipe. However, the system of the robot need to be improved by using sensors to auto

detect the maximum pipe diameter.

1

CHAPTER 1

INTRODUCTION

1.1 Background

In west Malaysia alone, the length of sewerage pipe has exceeded 15000 km.

With such length, monitoring and maintenance are not easy tasks. There are also other

pipelines in used for other purposes such as urban gas, chemical plant and chemical plant

which is mostly used by developed nations. Pipelines are a means of transporting oil and

gas for a very long time. Years of usage will bring it to aging, corrosion, developed cracks

and mechanical damages. This is why inspection, maintenance and repair need to be

done. However, this continuous activities requires enormous amount of budgets. Thus, a

low cost robot suited for multiple pipe dimension along with integrated maintenance

program need to be designed.

Wheel type system is the most popular system for pipe inspection robot because

it has the fastest speed among other types. Because all of its wheel is in contact with the

inner pipe surfaces, they have more grip than other types. They also has high torque and

carry large payload. However, due to the design they are usually not used in very small

pipe diameter. There are many types of wheeled pipe inspection vehicles already being

developed and used. Examples of them are LS-01 [1].

Wall-press type is a system that has becoming more popular for performing pipe

inspections tasks. They are nominally design for 10 inches pipe diameter [2]. The driving

modules adjust the whole robot dimension to fit exactly into the pipe. They produce

enough grip and torque to even be able to climb a pipe vertically. The steering motion is

done by varying the speed of each of its driving module. Examples of wall-press type

robot is MRINSPECT III and MRINSPECT IV [3].

2

1.2 Motivations

The varying size of pipe diameter used in pipelines requires multiple robots to

perform pipe inspection tasks. However, having multiples pipe inspection robots will

increase operating and maintenance costs. On the other hand, having a wall-press robot

that can inspect various diameter of pipe will reduce overall costs. Importance of a wall-

press type lies on the fact that it is able to climb steep pipe and also fit in various diameter

of pipe with a single robot.

Pipe inspection task is an important task in maintaining the condition of pipelines

used for sewerage, transporting oils and gas and other liquids. Operations by human,

autonomous vehicles and remotely operate vehicle required high costs, introduce high

risk and required dedicated surface support. Therefore, it is wise to reduce overall costs

wherever possible. Usage of wall-press type has an outstanding mobility and able to

comply with complicated pipe geometries [4]. This robot can fit various pipe dimension

and inspect pipe conditions in a cost-effective manner compare to having multiple robots

for various pipe dimensions.

Furthermore, pipe inspection robot is a helpful vehicles for maintaining pipe

condition. For example, wheel typed robot can be fit in with various sensors to detect

possible gas leakage in pipe. A robot equipped with necessary tools to perform welding

task can also fix minor leakage inside the pipe. Robot fixed with laser can be used to

detect pipe surface anomaly [5]. Since pipe inspection robot are becoming more popular

as the main method for pipe inspection tasks, more technologies will be developed and

this will increase the competition. As competition increases, prices will decline and non-

destructive inspection will come justified even for pipes with relatively moderate

consequences of failure [6].

3

1.3 Problem Statements

To develop a pipe inspection robot that able to perform pipe inspection task, it

must be able to overcome various pipe dimension and conditions. The most basic ability

of pipe inspection robot is to view the conditions of inner pipe. Among the information

needed to be gathered are the pipe inner conditions, angle of the robot, speed of the robot

and distance travelled by the robot. With this information, a thorough pipe inspection can

be performed.

For angled pipelines, the robot needs to be able to climb without slipping. A more

angled pipelines will be more difficult for the robot to climb. The grip and torque required

will be provided by its driving module.

For pipe with obstacles, it should be able to overcome this by reducing its overall

size to move more freely inside the pipe. A camera is needed to detect inner pipe

condition so that the vehicles can do the necessary adjustments.

Furthermore, camera controller and electronic speed controller need to be

developed. Camera provide views inside the pipe, whereas speed controller adjust robot

size, speed and directions.

1.4 Objectives

The objectives of this project are:

1. To design, develop and fabricate pipe inspection robot platform.

2. To develop working programs to remotely control the robot operation.

3. To test the pipe inspection robot system for simple pipe inspection application.

4

To develop the pipe inspection robot, all of the components operation is studied

and tested carefully before being installed into the waterproof body and modules. To

develop a program for pipe inspection, servo motor will be controlled by the Arduino

board to control the pan and tilt of the camera. Sensors is used to return values while

inside the pipe for program to act accordingly. Various tests need to be carried out to test

the effectiveness of pipe inspection robot for simple pipe inspection application.

1.5 Scope

This project is focusing mainly on developing a pipe inspection robot. This robot

will be able to perform a simple operations at a suitable speed and has some maneuvering

ability. It is built primarily for operation in 200 mm pipe diameter. This means that, this

pipe inspection robot will work best in a 200 mm pipe diameter.

Arduino is used as the main control unit for this pipe inspection robot. DC geared

micro motor, DC geared motor and servo motor are used as the system actuators. DC

motors is used for driving modules and robot’s size expansion. Servo motor is used to

adjust the viewing of the robot.

In order to develop a reliable program for the robot, system programming is

developed in several parts and its electronic circuit is carefully planned and constructed.

1.6 Outlines of Report

This report contains five chapters. The first chapters is an introduction chapter

which discussed the background of pipe inspection robot, motivation to develop pipe

inspection robot, problem statement, objectives of this project, scope and outlines of the

report.

5

The second chapter is literature review. For this chapter, outcomes from

researching on the scope of the project is covered to give and overview of what is

available and the latest technology available in pipe inspection robot design. Besides that,

theory relevant for pipe inspection robot is also included.

Next, third chapter describes the methodology for pipe inspection robot

development. All steps involved are recorded and explained in detail in this chapter. In

this chapter also, all the mechanical drawing and circuit design of hardware are also

stated. Finally, this chapter discusses the method used to measure the performance of this

pipe inspection robot.

In the fourth chapter, all the experiment results are analyzed and the performance

of the robot are discussed. Furthermore, simulation results are also recorded.

The final chapter contains the conclusion in regard to this project. Last but not

least, suggestion for future research are also included within this chapter.

6

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

Figure 2.1 shows the multiple types of robots available to perform pipe

inspection. However, wall-press type has becoming more popular than others for

performing pipe inspections. This is because they have the flexibility to fit into more

sizes of pipe and reduce the whole operation costs. In this chapter, seven types of pipe

inspection robots are discussed. They are wheel type, caterpillar type, wall-press type,

walking type, inchworm type, screw type and electro-magnetic force type.

Besides, components descriptions needed for pipe inspection robot are also

included in this chapter. Some of the components discussed are microcontroller board,

dc motor, motor driver, servo motor, joystick, camera and monitor.

Figure 2.1: Classification of pipe inspection robots (a) Pig type (b) Wheel type (c)

Caterpillar type (d) Wall-press type (e) Walking type (f) Inchworm type (g) Screw type

[3]

7

2.2 Wheel type

Wheel type robot typically have at least 4 set of wheel. Each wheels can be driven

independently or through differential drive.

2.2.1 Direct drive

The turning motion is controlled by changing the direction of all the motors.

Because each wheels is connected to its own motor, this configuration will have the

highest total torque available. Thus, more load can be pulled or carried with this setup.

This configuration required a motor each for its wheel as shown in Figure 2.2.

Figure 2.2: Wheels independently connected to motor [7]

2.2.2 Differential drive

Differential drive configuration shown in Figure 2.3 allows usage of less amount

of motor. However, the torque available will also be lower.

Figure 2.3: Differential drive [8]

8

2.2.3 Tractive vehicles

Tractive vehicles is a 4 wheeled robot with a direct drive motors [9]. To achieve

high torque, harmonic gears is utilized to deliver motor output to the wheels. Two

transwheels are used as the front wheels to able the robot to move sideways. To perform

steering capabilities, two wheels are placed at the back. Each of these 4 wheels are not

connected to the same motors. Because of the types of wheels used, this setup is able to

move spirally in a pipe. Dimension of this robot is controlled by the air cylinder situated

in the middle of the robot. Thus, it can be used in varieties of sizes and shapes of

pipelines. However, three cameras need for overall design. Two camera will be wasted

to monitor the steering wheels. Figure 2.4 shows the plain structures of a tractive

vehicles.

Figure 2.4: Plain structures of tractive vehicles [9]

2.3 Caterpillar type

Tracks or treads are placed over the wheels to create this configuration. Although

they do not provide an increase in torque, they do provide more grip to reduce slips and

distribute the weight of the robot. Thus, it is beneficial when pipe contains sand and

gravel. However, usage of tracks could caused damages to inner pipe surface and causes

the tracks to wear out.

9

2.3.1 LS-01

Figure 2.5 is a LS-01 prototype model which is a 4 wheeled type with tracks over

the wheels.

Figure 2.5: LS-01 prototype model [1]

This robot has a foldable top platform acting as camera holder. Standard

differential drive system is used to obtain more grip. The visual feed is captured by a

camera and transmitted to outside view through a visual feed cable. DC brushless motor

used as the actuator along with encoder, gearing system and motion controller.

Fabrication of this robot requires aluminum 6061 for its low density, good strength-to-

weight ratio, corrosion resistance and reasonable costs.

2.4 Wall-press type

Wall-press type robot are most widely used in today pipe inspection robot

configuration. This configuration allows free movement along the basic configuration of

pipelines, both horizontal and vertical. This setup also allows the robot to travel along

reducers, elbows and provide steering mechanisms. Most referenced design is

MRINSPECT (Multifunctional Robotic Crawler for INpipe inSPECTion).

10

2.4.1 MRINSPECT III

MRINSPECT III [3] consists of 2 independent vehicles segment connected via a

steering mechanism called Double Active Universal Joint (DAUJ). DAUJ provide the

robot with omni-directional steering capabilities as shown in Figure 2.6.

Figure 2.6: MRINSPECT III [3]

“DAUJ acts like a stiffness controllable two DOF joint and it makes it possible to control

the compliances of active joint in steering” [4]. 3 wheels is located at each articulated

bodies, circumferentially 120° apart. Pantograph mechanism with a sliding base ensures

natural folding and unfolding of the body. This configuration has the advantages of

reducing the undesirable forces exerting on the body when robot goes over obstacles.

Front body guides the motion and rear body drive the whole setup. The forces acting on

the wall is determined by the reflective forces of the spring.

2.4.2 MRINSPECT IV

MRINSPECT IV [3] shares similar aspect as earlier version of MRINSPECT

robot. The latest improvement is the miniaturization of the robot shown in Figure 2.7.

11

Figure 2.7: MRINSPECT IV [3]

The new improved design has a body frame that mounts a camera assembly and driving

modules. Each driving modules has a foldable linkage and located circumferentially 120°

apart. Driving module is powered by dc motor with encoder and reducer. Each driving

module is controlled independently. Therefore, tractive force is amplified and providing

the robot its steering capability. The motion of robot is controlled by controlling the speed

differences of each driving module. With differences in driving module speed, thus able

to steers its own body.

2.5 Walking type

Figure 2.8 shows a walking type robot often referred as crawler robot [10] or

tube-crawler robot. This type normally has eight identical two-links legs attached to a

body by a revolute joint or hip joints. All the leg links are rigid rod connected by revolute

joints or knee joints. The advantage of walking type robot is the ability to move around

almost any surface, obstacles and complex shaped hollows. Disadvantages however, it

requires more energy to operate the robot and has a complex controller.

12

Figure 2.8: Tube-crawler [10]

2.6 Inchworm type

This type of robot imitate the movement of inchworm. The movement however

is usually very slow. But, it is possible to design a robot that can fit very small pipe

diameter.

2.6.1 MARK IV

MARK IV [11] is designed to inspect pipe conditions from the outside surface of

the pipe. Its basic structures consists of three major components. The first component is

its flexible arm which has 7 links and 6 joints shown in Figure 2.9.

Figure 2.9: MARK IV basic structure [11]

13

This is to allow better adaptability to the surface of the pipe. At both end of the

arm, situated two air suckers for climbing up along the pipe. Next component is the slide

rail which is responsible for sliding mechanisms of its arm. Last component is Shape

Memory Alloy (SMA) actuators. SMA is used as it has high output-to-weight ratio

similar to human muscles. In order to move forward, air suckers fixed flexible arm (A)

to the pipe and slide flexible arm (B) through slide belt. Then, flexible arm (B) fixed

itself to the pipe and slide flexible arm (A) forward. This process repeated to move the

whole structure causing it to move very slow.

2.6.2 Pneumatic line based inchworm type

This type of robot is designed with an extensible body. At the end of the body

located a clamp to assists the movements of the robot. Figure 2.10 explains the working

principle of pneumatic inchworm.

Figure 2.10: Pneumatic inchworm working principle [12]

14

The movement is realized by clamping its rear clamp to the pipe and extending its body

forward. Then, the front clamp will clamp to the pipe and release its rear clamp. Finally,

the body compress itself back.

2.7 Screw type

Screw type robot has the same principle as a screw. At least two wheel is required

for this design. The wheel is positioned slightly at an angle so that when it rotates the

body will move forward or backward. Figure 2.11 shows front and side views of a screw

type robot.

Figure 2.11: Screw principle robot design [13]

When driving torque is applied, the body rotates and moves circumferentially in Y-axis

direction. Hence, robot moves forward. The whole robot “run forward is a spiral motion

similarly as a screw which rotates along the screw groove and moves forward” [13]. To

move backward, a reverse driving torque need to be applied.

15

2.8 Electro-magnetic force type [14]

Another type of micro robot designed based on electromagnetic actuator mounted

around its main body. Advantage of this design is the micro size of the robot starting as

low as 20 mm pipe diameter. The movement of this electromagnetic robot is controlled

by applying different voltage with different frequencies. Another advantage over other

design is the low power consumption of this design requiring around 1.2 watt while

travelling at a speed of 6-8 mm/s. Drawback of this design is the moving mechanism

which only able to move one direction.

2.9 Comparison of pipe inspection robots

Comparison of available pipe inspection robot types is tabulated in table 2.1.

Wheel and caterpillar type is the easiest to design with limitation from its electronic

components and actuators. But, it has the easiest steering mechanisms. Wall-press type

robot has its steering mechanism through the differential in speed of its driving module.

Inchworm, screw and electro-magnetic force type is the hardest to steer due to its

mechanical design which ease its forward movement.

Wall-press and walking type is best suited for pipe with varies diameter due to its

mechanical design which allow it to expand or shrink it sizes. The other designs have a

fixed size suitable for pipe with a more constant diameter throughout its length.

The actuators will determined the robot movement speeds. Wheel, caterpillar,

walking and screw will be a lot faster than the other types because the motors is

connected to either the wheels, tracks or its body. Inchworm will be very slow due to the

expanding and shrinking process of its body.

16

Table 2.1: Comparison between pipe inspection robots

Type Steering

ability

Robot size Advantage Disadvantage

Wheel Easy Fix size Very fast

movement

speed and can

carries high

payload

Possibility to

slips inside

pipe

Caterpillar Easy Fix size More grip than

wheel type

Possibility to

damage pipe

inner wall

Wall-press Medium Varies with

pipe diameter

Ability to

climb pipe

vertically

Low payload

due to small

actuators

Walking Easy Limited size Ability to

move almost

any surface

Requires

complex

controller and

most power

consumption

Inchworm Hard Micro size Micro size

enable it to a

Very slow

movement

speed

Screw Hard Fix size Highest

payload and

grips

Hard to move

in pipe

branches

Electro-

magnetic force

Hard Micro size Lowest power

consumption

Can only move

one direction

2.10 Components required

Understanding the requirements for each components needed is important before

developing a pipe inspection robot. Functions of all components can be seen in Table

2.2. A microcontroller board is required as the brain of the robot, its main control unit.

This microcontroller will need several input and output pins to communicate between the

user and other electronic components inside the robot. DC geared micro motor will be

used as its main driving module. This micro motor has to be small enough to fit in the

design but provides enough torque to drive the robot. Next, DC geared motor needed to

expand the robot size to fit variable sizes of pipe diameter. Besides that, motor driver is

an efficient method to control all the motor. Motor driver able to provide control to motor

17

direction and speed. Furthermore, servo motor will be used to control the pan and tilt

movement of the camera. This will ensure more area is covered by the camera. Last but

not least, a camera which will provide views for pipe inspections and a GUI to operate

the robot.

Table 2.2: Components function

Component

Function

Microcontroller board Main control unit

DC geared micro motor Main driving module

DC geared motor Expend robot to pipe diameter

Motor driver Control direction and speed

Servo motor Control camera movement

Camera Capture views inside pipe

Graphical User Interface Control robot operation and camera

display

2.11 Summary

Wall-press type will be the ideal shape for pipe inspection robot. By comparing

all types of robot previously used in pipe inspection robots, wall-press type provide more

flexibility for moving in multiple pipe dimensions. Since the driving module is located

circumferentially 120° apart it has high tractive force and this enables it to climb pipe

vertically. Steering mechanism of this type is inferior only to wheel and caterpillar type.

This robot will need at least two bodies each with its own set of driving module. Each

set will consist of three driving modules. Speed is not an important factor for this design

as inspection of pipe is a thorough process.

To develop a pipe inspection robot, several electronics and actuators are required.

A microcontroller board will act as the main control unit and handle all the interaction

between the actuators, electronics and operators. GUI will serve as the controller to

receive video feeds and control robot movements.

18

CHAPTER 3

METHODOLOGY

3.1 Introduction

In this chapter, method used to design and develop a pipe inspection robot is

described in details. This pipe inspection robot can be adjusted to fit into a pipe with

diameter of 200 mm. Besides that, it can climb vertical slope. This pipe inspection robot

has a steering mechanism by adjusting its driving module speed.

Section 3.2 in this chapter will also provide an overview of all the methods used

in this project. The methodology is also described using flowchart. While in section 3.3,

design specification of pipe inspection robot is described. Next, section 3.4 state the

selection of project requirements. Besides that, mechanical system development and

system programming are also covered in section 3.5 and section 3.6 respectively. After

that, section 3.7 will cover testing of robot with various surface conditions and vertical

slope climbing. Section 3.8 will evaluate the robot performance before the last section,

section 3.9 conclude this chapter.

3.2 Flow Chart

Flow chart shown in Figure 3.1 is the research methodology. First of all, robot

specification need to be decided. Before fabrication, shape, size and features of the robot

need to be determined. Next step is to choose suitable hardware and electronics

component to be used. Third step is to design the robot model using 3D CAD software.

Software chosen is SolidWorks. Once 3D modeling is finalized, next step is fabrication.

19

Figure 3.1: Research methodology flow chart

Fourth step will be programing of pipe inspection robot system. This pipe

inspection robot will have ten actuators. Actuators used are six DC geared micro motor,

two DC geared motor and two servo motor. To properly construct the system, all the

components are divided into four sections. Each section is tested separately to ease

troubleshooting process. Arduino Micro was used as the main microcontroller inside the

robot.

After all hardware and electronics components assembled, individual test is

carried out to ensure robot operate according to desired program.

20

Sixth step will be the testing of robot in multiple slope configuration. Finally, all

the recorded results will be analyzed to evaluate robot performance.

3.3 Design Specification

Before developing the prototype, it is important to determine all the parameter of

this pipe inspection robot. The most important parameters is the shape of the robot. Wall

press type is chosen as the basic shape for this pipe inspection robot. It is suitable for

various pipe diameter and provide the best traction while inside the pipe.

As shown in Table 3.1, the desired robot specification is done. This is to build a

sufficient size pipe inspection robot that can be easily fit all the hardware and electronics

required to operate this robot.

Table 3.1: Desired robot specifications

Pipe size 200 mm diameter

Input Voltage 12 Vdc

Weight Less than 2 kg

Total length 500 mm

Speed 0.1 m/s

Number of micro metal gear motor 6

Number of dc geared motor 2

Number of servo motor 2

Camera 1

Camera viewing angle 180° both vertical and horizontal

Based on Chapter Two, 6 driving module needed for this robot with each driving

module having its own motor. The position of each driving module is separated 120°

circumferentially. This is to ensure the stability of the robot and provide maximum

traction on all directions of the pipe.

21

Independent driving module is an important component to this design. In this

project, each driving module is equipped with its own motor. By having different speed

on its driving module, steering of the robot is achieved.

Some pipe inspection robot are able to turn more sharply due to mechanically

controlled joint. However, this was not considered in the design because it will

complicate the mechanical system and harder to implement in the programming. Instead,

it will be designed with a universal joint which will provide passive turning in horizontal

direction.

Furthermore, two servo motors will be needed for controlling the movement of

camera. The camera will be situated at the front of the pipe inspection robot to provide

more than 180° viewing angles. Table 3.2 shows detailed dimension of the pipe

inspection robot.

Table 3.2: Dimension of pipe inspection robot

Part

Length

Body

Total length

Compartment 1 length

Compartment 2 length

Camera enclosure length

Universal joint length

Minimum diameter

Maximum diameter

542 mm

103 mm

123 mm

117 mm

58 mm

145 mm

230 mm

Compartment

Outer diameter

Inner diameter

82 mm

79 mm

Driving module

Length

Width

Height

49 mm

30 mm

118 mm

Camera enclosure

Outer diameter

Inner diameter

Base height

Cage height

76 mm

70 mm

32 mm

85 mm

22

Table 3.2: Continued

Weight

Total

1.53 kg

3.4 Project Requirements Selections

Several types of actuators and microcontroller are needed to develop the pipe

inspection robot. This section states all the chosen components. Reasoning for

component selection are included within this section. They are listed below.

1. Arduino Micro ATmega32u4

2. Motor Driver

3. DC Micro Metal Geared Motor 45 rpm.

4. DC Geared Motor SPG30-60K

5. Micro Servo Motor MG90s

6. Camera JK-801

3.4.1 Arduino Micro ATmega32u4

Main control unit of this pipe inspection robot will be using Arduino Micro

ATmega32u4. This microcontroller has built-in USB communication, eliminating the

need for a secondary processor. This board consists of 20 digital pins which can be used

as input or output. Seven of this pins can used as PWM outputs while 12 of the pins can

be used as analog inputs. Each analog inputs has a resolution of 10 bits. Besides that, this

board also has a 16 MHz crystal oscillator, an ICSP header and a reset button. It contains

everything needed to be able to control this pipe inspection robot. Most importantly, the

miniature size of this board justifying the selection to use for this pipe inspection robot.

Figure 3.2 shows the image of Arduino Micro ATmega32u4.

23

Figure 3.2: Arduino Micro Atmega32u4 front view [15]

3.4.2 Motor Driver

Motor driver are the electronic circuits or IC to control the rotation direction and

the speed of the motors.

3.4.2.1 L293D and 74HC595

L293D is a 16 pin IC used to control 2 motors. 2 input pins, 2 output pins and 1

enable pin are required to control a single motor. L293D consists of quadruple half H-

bridge which is a circuit that enable the motor to move in both directions. L293D able to

supply 600 mA current for continuous operation and has a peak of 1.2 A for each channel.

It also support a wide supply voltage ranging from 4.5 Vdc to 36 Vdc. Figure 3.3 shows

L293D block diagram and Table 3.3 shows the truth table for each driver. Each drivers

in L293D are enabled in pairs. Driver 1 are paired with driver 2 and enabled by 1,2EN

while driver 3 are paired with driver 4 and enabled by 3,4EN. To run the motors, the

enable pins need to be high to activate their output and the output will be in phase with

their inputs. If the enable pins is low, there won’t be any output because the driver are

disabled and are in high-impedance state. Each pair of this driver forms a full-H bridge

which allow motor to be run in both directions.

24

Figure 3.3: L293D block diagram [16]

Table 3.3: Truth table for each driver

INPUTS

OUTPUT

Y

A EN

H H H

L H L

X L Z

For this pipe inspection robot, 4 ICs will be required to control the 6 motors in

the driving modules. However, this will requires 16 pins from the Arduino to control all

the motor. This is solved by inserting two shift register 74HC595 to transmit the input

signal from the Arduino to the motor driver. Figure 3.4 shows L293D pin configuration

while Figure 3.5 shows 74HC595 pin configuration. 74HC595 is an 8bit Serial to Parallel

shift register with latch. It requires 3 pin from the Arduino for latch, clock and data pins.

By daisy chaining two shift register, 16bit of data are achievable while still maintaining

3 pins connected to the Arduino. 6 pins required for motor speed will be connected

directly to the Arduino. Each shift register will be paired with two L293D in each section

of the robot.

25

Figure 3.4: L293D pin configuration [16]

Figure 3.5: 74HC595 pin configuration [17]

3.4.3 DC Micro Metal Gear Motor 45 rpm

DC micro metal gear motor is a miniature motor with a dimension of 40 mm x

12 mm x 10 mm. It typically run at 3 Vdc to 9 Vdc. When there is no load, it will run at

45 rpm while using 40 mA of current. While running with load, it will consume 360 mA

of current and provide a torque of 1.8 kg.cm or 0.177 N.m. Advantage of this motor is

that it is a very small motor and will fit nicely inside the driving module. It also weighs

10 g. Figure 3.6 shows the size of dc micro metal gear motor.

26

Figure 3.6: DC micro metal gear motor [18]

3.4.4 DC Geared Motor SPG30-60K

DC geared motor used for this pipe inspection robot expansion used 12 Vdc as

its input voltage. This motor has an output power of 1.1 W. At 12 Vdc, it has a rated

speed of 58 rpm and provide 0.255 N.m of rated torque while drawing 410 mA of current.

Figure 3.7 shows the shape of dc geared motor.

Figure 3.7: SPG30-60K [19]

3.4.5 Micro Servo Motor MG90s

MG90s is an analog micro servo motor. Servo motor is used in controlling the

camera due to its precise angle movement. Servo motor can be programmed to move

27

precisely in 1° increment or decrement. At 4.8 Vdc, this servo motor has a rated torque

of 1.8 kg.cm or 0.177 N.m and moves at a speed of 0.10 second for every 60°. Maximum

range for this servo is 180° and it has metal gear construction. Figure 3.8 shows servo

motor SG90.

Figure 3.8: Micro servo motor MG90s [20]

3.4.6 Camera JK-801

The camera used for this pipe inspection robot is a mini CMOS CCTV camera

JK-801. Image sensor used in this camera is a ¼” Color CMOS. It has a horizontal

resolution of 420 TVL providing 720 (H)*576 (V) in PAL and 720 (H)*480 (V) in NTSC

mode. This camera also has an auto white balancing thus easing the capture process in

dark area. Minimum illumination for this camera is 0.05 lux while consuming 9 Vdc of

voltage input and 70 mA of current. Figure 3.9 shows the shape of the camera.

Figure 3.9: Mini CMOS CCTV camera JK-801 [21]

28

3.5 Mechanical System Development

Mechanical system development for this robot will be divided into two phases.

The first phase will be 3D modeling using SolidWorks. All dimension and details of this

pipe inspection robot is drawn into the program. Once the dimension is satisfied and

finalized, it is then fabricated in fabrication phase.

3.5.1 3D Modeling Using SolidWorks

SolidWorks is a program used to draw the model of the pipe inspection robot.

Each parts of the robot is drawn into separate parts. All electronic components are also

included in the drawing to provide a clearer visual representation of the actual pipe

inspection robot. Figure 3.10 shows the schematic drawing for the total length of the

robot while Figure 3.11 shows the maximum diameter of the robot.

Figure 3.10: Schematic drawing of the total length of the robot

29

Figure 3.11: Schematic drawing of the maximum robot diameter

The front section and the back section of the robot are different only in the length

of the electronic compartment. Figure 3.12 shows the schematic drawing of the front

section of the robot and Figure 3.13 shows the schematic drawing for the driving module.

Figure 3.12: Schematic drawing for the front section

30

Figure 3.13: Schematic drawing for the driving module

The other two mechanisms used in this robot are the camera pan and tilt

mechanism and the universal joint. Figure 3.14 shows the schematic drawing for the

camera pan and tilt mechanism and Figure 3.15 shows the schematic drawing for the

universal joint.

Figure 3.14: Schematic drawing for the camera pan and tilt mechanism

31

Figure 3.15: Schematic drawing for the universal joint

After all parts drawn, it is assembled together to form the whole structure. Figure

3.16 shows the external frame assembly of the pipe inspection robot drawn in

SolidWorks. Whereas, Figure 3.17 shows the internal frame assembly of the pipe

inspection robot. The robot is divided into three sections, camera enclosure, front section

and back section. On the connector connecting the driving module to the electronics

compartment, there is holes in the middle for wires to pass through. Driving module

assembly is shown in Figure 3.18. Driving module for this robot uses one motor situated

90° perpendicular to the wheel axle. It is then connected through the usage of two bevel

gears.

32

3.5.2 Fabrication

Fabrication of this robot is done using a 3D printer which is for rapid prototyping

purposes. The purpose of using a 3D printer is to save cost to build this pipe inspection

robot prototype. Once all the files are finalized, it is then converted into STL files for use

by the 3D printer. The 3D printer uses PLA as its printing filament. PLA is a bio-

degradable polymer produced form lactic acid. It is also harder than ABS and melts at

around 180°C to 220° C. Printing is done parts by parts considering some parts are large

and require very long time to print. All parts are printed before and programming is done.

Figure 3.16: External frame assembly

33

Figure 3.17: Internal frame assembly

Figure 3.18: Driving module assembly

34

3.5.2(a) Camera Enclosure

Camera enclosure is used to enclose two micro servo motors and one camera. The

enclosure is separated into 3 parts: base, cage and camera plate. Camera plate will hold

the camera while it is being rotated by the servos. The base is used to assemble every

parts together with the front section. Cage will provide protection against any contact

while doing inspection works. Top view of the base is shown in Figure 3.19 while Figure

3.20 shows the cage. In Figure 3.21, the camera plate assembly is shown with camera

and two servo motor assembled together.

Figure 3.19: Base top view

Figure 3.20: Cage top view

35

Figure 3.21: Assembly of camera and servo motors

3.5.2(b) Driving Module

Driving module for this pipe inspection robot prototype is slightly different

compared to the actual 3D design drawn in SolidWorks. This is due to the 3D printer not

being able to print the desired design. In the printed parts, the motor is located at the

lowest positon of the arm replacing the wheel axle. Wheel is connected directly into the

motor shaft and the other wheel is a dummy wheel for support. Ensuring the printed

prototype do not differ a lot compared to the original drawing. Figure 3.22 shows the

actual printed arm. The wheel used is Pololu wheel with diameter of 32mm and width of

7mm.

36

Figure 3.22: Driving module arm

3.5.2(c) Electronic Compartment

Compartment to store all the electronics and wiring is made up of a simple

cylindrical shape. One dc geared motor is assembled inside the compartment for

expansion and contraction of the driving module arms. This allow the robot to pass

through any obstruction inside the pipe. Installation of the dc motor inside the

compartment is shown in Figure 3.23 and Figure 3.24 shows the threaded rod used for

expansion and contraction.

37

Figure 3.23: DC motor inside electronic compartment

Figure 3.24: Threaded rod for expansion and contraction

38

3.6 Embedded System Development

Development of the embedded system for this pipe inspection robot will be

focusing on control circuit design, main controller programming, graphical user interface

and testing of the robot. Control circuit of this pipe inspection robot is responsible for

controlling speed, direction and position of the actuators. Next, main controller will be

programmed to receive serial data from PC and then process is to control the actuators.

Before starting to program the main controller, it is important to understand the behavior

of all actuators used. For this pipe inspection robot, 10 actuators are used and will be

divided to three parts. Development steps for each parts are stated in detail in following

sections. Block diagram for this pipe inspection robot embedded system development is

shown in Figure 3.25.

Figure 3.25: Block diagram for embedded system

39

3.6.1 Driving Module

Driving module for this pipe inspection robot consists of 74HC595 shift register,

two L293D motor driver, one dc geared motor and three DC micro metal geared motor

for each module. This pipe inspection robot has two driving modules. Shift register is

required to reduce amount of pins connected to Arduino. Figure 3.26 shows the

connection between shift register and motor driver for front driving module.

Figure 3.26: Connection between shift register and motor driver for front driving

module

Both shift register and motor drivers run on 5 Vdc while motor connected to

motor pin runs at 9 Vdc supplied through VCC located at pin 8 of L293D motor driver.

Positive and negative leads of each motor is connected to its driver pairs of A and B. For

front driving module, PWM1, PWM2 and PWM3 is connected to pin 3, 5 and 6 of

40

Arduino respectively. DATA is connected to Arduino pin 11 while LATCH is connected

to Arduino pin 8 and CLOCK connected to Arduino pin 12. DATA2 will be connected

to DATA of the back driving module. This is because two shift register can be linked

together to transmit 8bit of data. CLOCK and LATCH for the back module will share the

same pin configuration on the Arduino. Figure 3.27 shows connection between shift

register and motor driver for back driving module. PWM4, PWM5 and PWM6 is

connected to Arduino pin 9, 10 and 13 respectively. Figure 3.28 shows connection from

shift register to Arduino.

Figure 3.27: Connection between shift register and motor driver for back driving

module

41

Figure 3.28: Connection from shift register to Arduino [15]

Then, a program is developed to allow Arduino to transmit data to shift register

and to motor driver. Before any data is transmitted to the motor driver, serial port has to

be initialized and it has to wait for data to be received from PC. Once data is received

from PC serial communication port, it is then compared to conditions inside the Arduino

program. Next, data is transferred to the shift register coding segment.

Coding segment for shift register will be divided to two parts, the looping routine

and shifting routine. The looping routine will be the codes that waits for selected data

from serial port and then compares it to programmed command. This command will then

store new data in an array. This array will then be shifted out with another routine, the

shifting routine. Each array will contain 8bit of data. Therefore, two array will be used

for front and back driving module labelled as “dataArrayFRONT” and

“dataArrayBACK”.

The shifting routine is done by using 3 pins. The first pin is the data pins, by

pulsing it up and down thereby communicating a data byte to the register bit by bit. The

42

second pin is the clock pin used to indicate exact position between bits. And the last pin,

latch pin is used transmit the whole byte. By having all output pins on the shift register

to output in parallel is known as the “parallel output” part. Since there is two data array,

the first data array to be transmitted is “dataArrayBACK” and then “dataArrayFRONT”.

This is because, shift register serially shift out the data from the MSB to the LSB and the

front driving module having the LSB while back driving module having the MSB.

Figure 3.29 shows the flow chart of programming code for receiving serial data

from PC and transmitting it to motor driver. For micro metal geared motor, pulse width

modulation is supplied to its corresponding enable pins to allow speed adjustment while

5Vdc is connected to enable pins for dc geared motor which is used for robot expansion

and contraction to increase or reduce its diameter.

Figure 3.29: Flow chart of programming code for receiving serial data from PC and

transmitting it to motor driver

43

The whole circuit is constructed on a stripboard. Each board contain one shift

register and two motor driver. Figure 3.30 shows the circuit constructed on a strip board.

Power supply on the board is divided into two parts. 5 Vdc is supplied through a

switching voltage regulator while 9 Vdc for motor is connected through another

switching voltage regulator connected to the green header located at the bottom right of

the circuit board. Figure 3.31 shows the switching voltage regulator used to supply 5 Vdc

and 9 Vdc to the board.

Figure 3.30: Circuit constructed on strip board

Figure 3.31: LM2596 switching voltage regulator

44

The motor will be controlled by the L293D motor driver. The output pins of the

L293D driver will be connected to this motor pins. The speed of the motor will be

controlled by the PWM pins connected to the L293D from the Arduino. Figure 3.32

shows various PWM duty cycle. Every duty cycle translates to motor speed percentage.

Figure 3.32: Various PWM duty cycle [22]

For this robot however, PWM will always be at 100% duty cycle. This is because

the robot motor speed is already slow due to its gear ratio with maximum 45 rpm.

3.6.2 Camera Pan and Tilt

Camera pan and tilt is controlled by using two micro servo motor. One of the

servo is used to rotate the camera view up or down while another servo is used to rotate

the whole camera. Figure 3.33 shown the connection between Arduino and servo motor.

Power and ground of both servo is supplied by the switching voltage regulator. As current

output from an Arduino pins is limited to 40 mA.

45

Figure 3.33: Connection between Arduino and micro servo motor [15]

To control servo motor with Arduino, a “Servo.h” library is used. This library

allows the Arduino to control up to 8 servo motors. First of all, the microcontroller will

initialize its serial port for communication to the PC. After that, it will read the serial data

received from the PC and compares it to conditions inside the program. The responding

command will then either increase or decrease the servo position angle for both servos.

Position of both servos are limited to only 180°. Figure 3.34 shows the flow chart for

servo programming.

46

Figure 3.34: Flow chart for servo programming

3.6.3 Graphical User Interface

To control the operation of this pipe inspection robot, a graphical user interface

is developed. This GUI contains button to control the direction of the robot, diameter of

the robot, camera and image capturing process, and camera viewing angles. Figure 3.35

shows the layout of the GUI.

47

Figure 3.35: Layout of the graphical user interface

After opening the application, users will be allowed to search for communication

port and camera. Once the GUI connected to the robot’s communication port, then only

the robot control button, diameter button and camera control button will be enabled. The

capture button and record button will only be enabled once a camera is connected. User

will still be allowed to connect to the camera even though the application is not connected

to the robot’s serial communication port. However, only capture and record button will

be enabled and camera control button will still be disabled. Figure 3.36 show the flow

chart for this graphical user interface.

48

Figure 3.36: Flow chart for graphical user interface

For serial port communication, when no button is pressed, a serial data of “0,” is

sent to the Arduino through the serial port. This data will be interpreted by the Arduino

as “STOP”. Motors will not be moving in this condition. Others serial data transmitted

will provide different interpretation to the Arduino. In total, 16 conditions will be

checked by the Arduino. However, this GUI will only transmit 1 serial data at a time.

Serial data transmitted by this GUI ranging from 0 to 15 is followed by a comma. This

comma is to indicate the end point of the data being transmitted.

When a camera is connected, pressing the capture button will capture the current

frame inside the video frame. The captured image will then be stored in a folder named

“Images” located in the application directories. This directory will open once image is

saved. For video recording, the application will collect the current frame and place it in

49

a recoding function. The application will collect 25 frames per second and combine it to

become a video. Once the record button is turn off, the record function is turn off and the

videos can be viewed from its saved directories named “Videos”.

3.7 Testing

Test are carried out after mechanical system are fabricated and system

programming and development of the robot is programmed and constructed. Major

consideration of the pipe inspection robot development are drivability, steering ability

and camera viewing vision.

3.7.1 Drivability Test

Drivability test is carried out to test both mechanical design and electronics.

Mechanical design are a major consideration for this robot. Without the proper

mechanical ability, all other parts will fail even though other parts are performing as

expected.

Drivability test is important to measure the capabilities of this pipe inspection

robot. Drivability test is done by controlling it to move in a 200 mm diameter pipe at

multiple angle in reference to the ground. To show the effect of a slope on the robot, time

is taken for it to move every 2 meters. Figure 3.37 show the method of setting up testing

ground.

50

Figure 3.37: Setting up of testing ground

Back part of robot is placed at the start point as the initial starting position. Time

is taken as soon as the operator control the robot to moves forward. Time taken is stopped

once the front camera cage reach the end point. Data is then recorded for analysis. This

test is carried out thrice for every angle from 0° to 30° in a 5° increment. Angle

calibration is done with a smartphone level balance. Figure 3.38 shows the calibration of

the pipe angle with reference to the ground.

51

Figure 3.38: Angle calibration with smartphone level balance

The total time for each slope angle is then averaged to be used in speed

calculation. Equation 3.1 shows the calculation for average time taken for every angle,

Equation 3.2 shows the calculation for distance travelled by the robot and Equation 3.3

shows the calculation for the speed of the robot for every angle.

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑡𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛 = 𝑡𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛 1+𝑡𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛 2+𝑡𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛 3

3

(3.1)

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑟𝑜𝑏𝑜𝑡 = 𝑡𝑜𝑡𝑎𝑙 𝑝𝑖𝑝𝑒 𝑙𝑒𝑛𝑔𝑡ℎ − 𝑟𝑜𝑏𝑜𝑡 𝑙𝑒𝑛𝑔𝑡ℎ

= 2000 𝑚𝑚 − 542 𝑚𝑚

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑟𝑜𝑏𝑜𝑡 = 1458 𝑚𝑚 = 1.458 m

(3.2)

𝑠𝑝𝑒𝑒𝑑 =𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑟𝑜𝑏𝑜𝑡

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑡𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛 (3.3)

52

The distance travelled by the robot that is 1.458 m will be used to calculate the

speed of the robot after the average time has been taken.

3.7.2 Camera viewing Vision

Camera is a very important components in this pipe inspection robot. Without it,

monitoring of internal pipe conditions will be almost impossible to do. Thus, it is

important to test the effectiveness of the camera used in this pipe inspection robot. This

is done by capturing pictures and recording videos while testing is ongoing. The resulting

pictures and videos must then be improved upon next testing. Improvement is done until

the required robot vision is obtained.

3.8 Performance Evaluation

In previous section, real time performance of the pipe inspection robot has been

discussed. Problems faced during testing and its solution has also been discussed. Videos

and photos taken during testing is used to benchmark the performance of the pipe

inspection robot.

3.9 Summary

In this chapter, the methodology is divided into two separate categories. The first

categories is designing and construction of the mechanical mechanism of the pipe

inspection robot. The other categories is designing, construction and programming of the

embedded system development. Testing is the most difficult part for this chapter since

many problem occurring during the duration of the test. However, improvement is

necessary to solve the problems. Speed and direction of the robot is altered using pulse

width modulation method to maintain a straight line motion for the robot.

53

CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 Introduction

Problem encountered in the previous chapter and results of testing will be

discussed in this chapter. In this chapter, there will be 4 section. The first section, section

4.2 discusses on the result of mechanical system development and section 4.3 discusses

on the results for embedded system development. After that, section 4.4 discusses on

results obtained during testing and finally section 4.5 discusses the real time performance

evaluation of the pipe inspection robot.

4.2 Result of Mechanical System Development

Complete pipe inspection robot is shown in Figure 4.1. There are three main

sections of the robots. The front camera section, front driving module section and the

back driving module section. Universal joint located between front and back driving

module section allow the robot to turn 90 degree to the left or right in a horizontal

movements. The performance of the driving module will be discussed in next section.

All moving parts are screwed using bolt and nyloc nuts to prevent the nut from

unscrewing itself while robot is still operating. Each driving module have 2 wheels

totaling to 6 wheels for each front and back section. Motor is securely placed inside the

driving module to ensure no loss parts. Front and back electronic compartment is made

up of different color to differentiate the differences in length.

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Figure 4.1: Completed pipe inspection robot

Figure 4.2 shows the internal view of the electronic compartment for this pipe

inspection robot. Arduino board and motor driver board are placed in a standing position

to allow easy placement and removal of the whole system from the robot. Switching

voltage regulator are located at the bottom of the electronic compartment cover to clear

space for wire connection between the motor driver and the front section electronics.

This method allows the whole electronics system to be removed in one piece by

disconnecting only the motor wire connected to the motor driver through the use of

header pins.

55

Figure 4.2: (a) Top view (b) Side view (c) Process of inserting the electronics into the

electronic compartment

Since this pipe inspection robot has 3 sections, each section need to be linked to

each other. Long thread and nuts are used to connect each section to the other and motor

are also screwed in place before any installation is continued. Figure 4.3 shows the long

thread used to connect the driving module to the electronics compartments.

Figure 4.3: (a) Long threads used to combine driving module with electronics

compartment (b) screw used to hold motor in place

56

Because the wires are connected from the camera section to the back driving

module section, it needs to be inside the electronic compartment as much as possible to

avoid from any possible obstacles that might damages the wires. Figure 4.4 shows the

wiring of the robot.

Figure 4.4: (a) Wiring from front to back section (b) Motor wiring passing through a

tube (c) Power and signal wire wrapped with cable wrapper

4.3 Result of Embedded System Development

There are three parts to this pipe inspection robot embedded system development.

The first part are the driving module while second part are the camera pan and tilt

function. Finally, graphical user interfaces made up the last part of this embedded system

development. This section will discuss the results for embedded system development for

this pipe inspection robot.

57

4.3.1 Driving Module

Based on Figure 3.24 in chapter 3, the circuit is used to control 4 motors. Three

of the motor is a DC micro metal gear motor and the other motor is a DC geared motor.

Operation of this circuit is controlled by three PWM pins from Arduino and three signal

pins from the Arduino. The signal pins consists of DATA, LATCH and CLOCK pins.

The board is power with 5 Vdc supplied by a switching voltage regulator. This is to

ensure that no current limitation will occur when operating 4 DC motors. Another

switching regulator is used to supply 9 Vdc to the L293D motor driver for motor power

supply. In this configuration, the 5 Vdc supplied for logic operation won’t be interrupted

by the motor power consumption.

Each driving module has its own DC micro metal gear motor to ensure that every

driving module that is in contact with the inner wall of the pipe will provide the robot

with grip and torque required for it to moves. Reliability of these motor will be discussed

in testing of the motor speed section.

4.3.2 Camera Pan and Tilt

Camera pan and tilt uses two servo to rotate both horizontally and vertically. As

shown in Figure 3.15, the camera is tested while the whole assembly is combined with

the driving module assembly. The camera rotation is tested inside the pipe with the

camera functioning as well. Figure 4.5 shown the view of the CCTV camera inside the

pipe while testing.

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Figure 4.5: (a) Camera view rotated 90° to the left (b) Camera view at 0° (c) Camera

view rotated 90° to the right

As seen in figure above, the images shows that the servo are unable to rotate the

camera exactly 90° to the left. This is due to several factors. The first factors is the

fabrication limitations. Although the design is expected to be able to achieve the desired

angle, 3d printer used to print the actual camera assembly are not able to print as

accurately as the required dimension. This cause some of the camera assembly to be loose

and decrease the rotation accuracy. Second factor is the servo used for this camera

assembly. Since micro servo is used, it is unable to provide enough torque to rotate the

camera fully according to the desired position. Figure 4.6 shows the position of the

camera when rotated to different position.

59

Figure 4.6: (a) Camera rotated 90° upwards (b) Camera at horizontal position (c)

Camera at rotated 90° downwards

However, we can say that the reliability of the camera is desirable. Good quality

images are able to be taken from the camera and the video recoded by this camera are

also good enough for monitoring purposes. This is also because, LED are used to increase

the ambience light inside the pipe.

4.3.3 Graphical User Interface

The application for this pipe inspection robot has been successfully developed.

The GUI are able to connect and control the robot. The GUI provide the user with the

robot movement control and dimension. This application is also able to capture images

directly from the camera inside the robot. Videos are also able to be recorded for later

reviewing purposes. This application will ensure that the operation of the robot is kept

minimized for smooth operation.

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4.4 Testing Results

Testing result will be discussing on the results of the drivability and the robot

vision.

4.4.1 Drivability Result

The speed for this pipe inspection robot is shown is Table 4.1. Testing is done

from 0 degree to 30 degrees only because for an angle more than 30 degrees, the robot

will not be able to climb. The motor used do not provide enough torque to drive the robot.

However, the motor does provide enough torque to hold the robot in place at an angle

more than 30 degrees.

Table 4.1: Speed of pipe inspection robot for various slope angle

Slope angle

Ɵ(°)

Time taken(s)

Average

time

taken(s)

Speed(m/s)

1

2

3

0 15.855 15.828 15.581 15.755 0.093

5 16.417 17.862 16.595 16.958 0.086

10 17.715 17.606 17.386 17.569 0.083

15 19.030 19.421 19.392 19.281 0.076

20 20.389 19.928 19.817 20.045 0.073

25 26.218 26.570 25.297 26.028 0.056

30 28.344 29.775 29.297 29.139 0.050

Data obtained are then plotted for speed against slope angle to show the effect of

higher slope towards the robot speed. Figure 4.7 shows a graph of speed against slope

angle.

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Figure 4.7: Graph of speed (m/s) against slope angle, Ɵ (°) with 100% duty cycle

By studying the graph, the effect of steeper slope angle will slow down the

movement of this pipe inspection robot. This can be improved by using a more powerful

motor which can provide higher torque than the current motor. Figure 4.8 shows the robot

successfully climbing inside the pipe at a 10° steep.

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 5 10 15 20 25 30 35

Speed(m/s)

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Figure 4.8: Pipe inspection robot successfully climbing inside the pipe at 10° gradient

For the robot to be able to move in a higher degree of slope angle, calculation

need to be done to find the amount of motor torque required to drive the robot forward.

First of all, coefficient of friction need to be calculated between the rubber wheel and the

PVC pipe, μ. Based on testing, at 35° slope angle, the robot does not move forward or

downward. This is the point of equilibrium for the robot. Using Eq. 4.1, coefficient of

friction is calculated. When the robot is in a state of equilibrium, the gravitational force

acting on the body downward the inclined slope is balanced by a frictional force acting

upward on the body. Figure 4.9 shows the position of the robot at Ɵ angle.

𝜇 =𝐹𝑃

𝐹𝑁

(4.1)

where 𝐹𝑃 = 𝑝𝑢𝑙𝑙𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒,

63

𝐹𝑁 = 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑓𝑜𝑟𝑐𝑒 𝑡𝑜 𝑝𝑢𝑙𝑙𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒,

𝜃 = 𝑎𝑛𝑔𝑙𝑒 𝑤ℎ𝑒𝑛 𝑟𝑜𝑏𝑜𝑡 𝑎𝑡 𝑒𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 = 35°.

𝜇 =

𝑚𝑔 sin 𝜃

𝑚𝑔 cos 𝜃

𝜇 = tan 𝜃

𝜇 = tan 35 °

𝜇 = 0.70

Figure 4.9 Position of robot at Ɵ degree angle

Once coefficient of friction is known, the required force to pull the robot forward

can now be calculated. By solving all the forces into its vector, the pulling force equation

is created as shown in Eq. 4.2.

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𝐹𝑝 = 𝑚𝑔(sin 𝜃 + 𝜇 cos 𝜃) (4.2)

where 𝑚 = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑏𝑜𝑑𝑦,

𝑔 = 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦.

An assumption made to ease calculation is that all the calculation is only for 1

driving module. Then, the pulling force is calculated by substituting the angle values,

coefficient of friction, mass and acceleration of gravity into Eq. 4.2.

𝐹𝑝 = (1.53)(9.81)(sin 𝜃 + (0.70)cos 𝜃)

To calculate the torque of motor, Eq. 4.3 is used.

𝜏 = 𝐹𝑝. 𝑟 (4.3)

where 𝑟 = 𝑟𝑎𝑑𝑖𝑢𝑠 𝑜𝑓 𝑡ℎ𝑒 𝑤ℎ𝑒𝑒𝑙.

Based on chapter 3, diameter of the wheel is given as 32 mm. By using Eq. 4.2,

a table of motor force and motor torque is constructed for multiple slope angles ranging

from 35° to 90°. Table 4.2 shows the amount of motor force and torque required to move

forward in a pipe at 35° slope to 90° vertical pipe configuration in a 5° incremental.

Table 4.2: Motor force and motor torque required for slope more than 30degrees to

achieve equilibrium

Angle(°) Motor force, Fp (N) Motor Torque, 𝝉 (N.m) at equilibrium

35 17.2 0.275

40 17.7 0.283

45 18.0 0.288

50 18.3 0.293

55 18.3 0.293

60 18.3 0.293

65 18.0 0.288

70 17.7 0.283

75 17.2 0.275

80 16.6 0.266

85 15.9 0.254

90 15.0 0.240

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Data tabulated in Table 4.2 shows that slope at 50°, 55° and 60° required the

highest motor torque to provide the robot with positive pulling force. The motor torque

decreases as the angle increases because as the pipe nearing vertical position, the friction

forces will decreases.

4.4.2 Camera Viewing Vision

In this test, several images are captured while the robot are actually inside pipe.

Most of the testing done is based on real time view. Videos are recorded for better result

presentation. Figure 4.9 show the comparison between the ambient light of the pipe when

the robot is tested without and with the usage of LED.

Figure 4.10: Comparison of the ambient light without and with the usage of LED

By comparing both images, usage of LED is justified in helping to increase the

ambient light of the pipe. The effect of LED on the camera of the robot can be verified

further by comparing the actual images taken by the camera. Figure 4.11 shows the actual

images taken by the CCTV camera with and without the usage of LED.

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Figure 4.11: Comparison of the actual images taken by the CCTV camera without and

with the usage of LED

The camera pan and tilt angle are limited by several factors that is servo motor

and hardware limitation. For this project, the camera are not able to rotate a full 90° to

both upwards and downwards position. To test the maximum angle the servo able to

rotate, an indicator is placed on top of the camera lens. Figure 4.12 shows the maximum

angle servo rotation. Rotation upward is limited to 63° while rotation downward is

limited to 70°. Rotation for horizontal movement are able to rotate both 90° left and right.

Figure 4.12: Servo maximum angle rotation

4.5 Real Time Performance Evaluation

The real time performance evaluation of this pipe inspection robot is done while

testing the robot moving in a pipe in multiple slope angles. The robot are easily able to

67

move when the pipe is parallel to the ground. Figure 4.13 shown the starting position of

the robot inside the pipe and the end position of the movement test inside the pipe.

Figure 4.13: (a) Robot starting at one end of the pipe (b) Robot end at the other end of

the pipe

The robot movement are also supported with the driving module being located

circumferentially 120° to each other. As evidently shown in Figure 4.13(a), the robot are

not parallel to the ground and yet it is still able to move through the pipe. This is because

all of the driving module are making contact with the inner wall of the pipe. Therefore,

this pipe inspection robot have enough grip and torque to moves forward itself in the

pipe. To accommodate the changes in pipe diameter, the driving module can also be

expanded or contracted for multiple pipe diameter. This changes in robot dimension is

done with the usage of two DC motors. Figure 4.14 shows the different diameter of the

robot while inside the 200 mm diameter pipe.

Figure 4.14: (a) Robot in a smaller diameter configuration (b) Robot in larger diameter

configuration

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4.7 Summary

All of the robot components are successfully tested and functioned. However,

while testing, a few problems occurs. Most critical issues are the camera ambient light.

This is solved by equipping the robot with LED to increase the ambient light. Besides,

the mechanical strength of the whole system need to be improved. In short, testing of the

robot need to continuously done to identify more areas that can be improved until a

perfect pipe inspection robot is developed.

69

CHAPTER 5

CONCLUSION & FUTURE WORK

5.1 Conclusion

For this project, there are three objectives. The main and first objective is to

design, develop and fabricate a pipe inspection robot platform. After series of testing,

this objective has been achieved successfully. The robot build has a dimension of 542

mm in length and has a maximum diameter of 230 mm. The pipe inspection robot has 3

section to it. The first section is the camera section followed by front driving module

section and lastly the back driving module. The diameter of the robot can be varying

from 150 mm to 230 mm in diameter to accommodate pipe with unsymmetrical diameter

or when there is obstacles present inside the pipe. The robot is able to climb a slope with

maximum angle of 30 degrees. Camera system on this robot allow the camera view to be

rotated inside the pipe to monitor pipe condition more thoroughly.

The next objective of this project is to develop a reliable working program and

application to remotely control the robot operation. This objective has been accomplished

successfully. The robot are able to move in a 200 mm pipe diameter without any help

from the operator. The application are able to control the robot to move front and back

and adjusting its diameter. Functions of the application also allows images to be capture

directly from the camera and stored in PC. Videos are also able to be recorded for details

analysis. Furthermore, the application are also able to provide a live view of the robot

camera.

The last objective of this project is to test the pipe inspection robot system for

simple pipe inspection application. Unfortunately, this objectives are completely fulfilled

as the material used to fabricate the robot are not strong enough to withstand the force

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provided by the DC motors. While testing on a steep angle, the driving module cannot

moves forward when the diameter of the robot are increase to provide the robot with grip

to hold it in place. Besides, when the diameter of the robot are larger than the pipe

diameter, it will clamp itself inside the pipe and won’t allow the robot to moves in any

direction. However, this proves that given a more powerful motor to drive the driving

module, the robot will almost certainly able to climb a vertical pipe configuration.

5.2 Future Works

Recommended future development for this pipe inspection robot include the

design of driving module. Size is very important for moving inside piping system.

Smaller driving module size and reduced number of module are needed to provide better

steering ability. Besides, sensors need to be included to automatically adjust the diameter

of the pipe inspection robot according to the piping size and pressure exerted to the pipe

wall. Furthermore, there is also a need for a leak sensor inside the driving module

compartment to detect any leakage. With this, operation of the pipe inspection robot can

be halted for safe retrieval of the robot. Finally, a more powerful micro motor need to be

developed to be equipped to this pipe inspection robot to allow it to climb pipe in vertical

position.

71

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