UNIVERSITI PUTRA MALAYSIA

DEVELOPMENT OF MOBILE MAGNETIC IMAGING SYSTEM BASED ON 1-D HALL SENSOR ARRAY

NG WEI SHIN

FK 2012 108

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DEVELOPMENT OF MOBILE MAGNETIC

IMAGING SYSTEM BASED ON 1-D HALL SENSOR

ARRAY

NG WEI SHIN

MASTER OF SCIENCE

UNIVERSITI PUTRA MALAYSIA

2012

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DEVELOPMENT OF MOBILE MAGNETIC IMAGING SYSTEM

BASED ON 1-D HALL SENSOR ARRAY

By

NG WEI SHIN

Thesis Submitted to the School of Graduate Studies,

Universiti Putra Malaysia, in Fulfillment of the Requirement for the Degree of

Master of Science

February 2012

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Abstract of thesis presented to the Senate of University Putra Malaysia in fulfillment of

the requirement for the degree of Master of Science

DEVELOPMENT OF MOBILE MAGNETIC IMAGING SYSTEM

BASED ON 1-D HALL SENSOR ARRAY

By

NG WEI SHIN

February 2012

Chairman: Associate Professor Norhisam Misron, PhD

Faculty: Engineering

Non-destructive evaluation (NDE) is one of the most common methodologies in the

industries proposed to examine the properties of ferromagnetic materials. The NDE

technique includes some kind of microscopy to examine the external surfaces of

specimens in detail which rely upon magnetic, ultrasonic and radiographic methods.

Therefore, NDE technique can be used to perform shapes evaluation of ferrous objects

without permanently altering its characteristic. The NDE technique used in this thesis for

shapes evaluation is based on the magnetization characteristic of ferrous objects.

This thesis describes the development of prototype Mobile Magnetic Imaging System

applying the NDE technique for the shapes evaluation of ferrous objects. The Mobile

Magnetic Imaging System is able to evaluate the shapes of ferrous objects underneath a

non-ferromagnetic surface with the application of magnetic imaging technique proposed

in this research. The magnetic imagings for the shapes of ferrous objects are

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accomplished by performing the 2-D contour plot with 2-D array matrix of induced

voltage signal, VH and magnetic field, B.

The operation of Mobile Magnetic Imaging System is based on the magnetic flux

leakage testing (MFLT) principle performed on the surface of ferrous objects. As the

system navigates across a ferrous object, the permanent magnets on the system

magnetize the ferrous object. The magnetized ferrous object forms the magnetic circuit

with permanent magnets, thus, develops the closed loop flow of magnetic flux, m. The

1-D Hall sensor array on the system is exposed to the magnetic field, B caused by the

flow of magnetic flux, m from permanent magnets to the ferrous object. The 1-D Hall

sensor array consists of linearly integrated solid state Hall effects sensors to detect the

magnetic field, B and translate to Hall induced voltage signals, VH. The Hall induced

voltage signals, VH from 1-D Hall sensor array are constructed into a 2-D array matrix

which is employed for magnetic imaging.

Lastly, the prototype of the Mobile Magnetic Imaging System is presented. In addition,

the performance parameters of Mobile Magnetic Imaging System are identified which

include the size of the specimen under evaluation, moving speed of system and thickness

of non-ferromagnetic surface above ferrous objects. Therefore, experimental results to

study the performance of Mobile Magnetic Imaging System are presented in this thesis.

Firstly, it presents the ability of the system in visualizing the shapes of ferrous object

specimens with magnetic images. In addition, the improvements towards magnetic

imaging technique of ferrous objects are proposed by considering the absolute value of

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induced voltage signals, |VH| and magnetic field, |B|. Secondly, the result presents the

ability of the system to visualize the shapes of actual ferrous objects employing

improved magnetic imaging technique. Lastly, the effect of perpendicular gap towards

accuracy of Mobile Magnetic Imaging System in shapes evaluation is studied. Based on

the experimental results, the optimized perpendicular gap for shapes evaluation is at

10mm.

In summary, the Mobile Magnetic Imaging System is proven to be able to visualize the

shapes of ferrous objects embedded underneath a non-ferromagnetic surface.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi keperluan untuk Ijazah Master Sains

PEMBANGUNAN SISTEM PENGIMEJAN MAGNETIK MUDAH ALIH

BERDASARKAN SUSUNAN PENGESAN HALL 1-D

Oleh

NG WEI SHIN

Februari 2012

Pengerusi: Profesor Madya Norhisam Misron, PhD

Fakulti: Kejuruteraan

Kajian Tanpa Kemusnahan (NDE) merupakan salah satu cara yang paling dikenali

umum dalam industri untuk mengkaji sifat-sifat bahan ferromagnetik. Teknik NDE

termasuk beberapa jenis mikroskopi untuk memeriksa permukaan luar spesimen secara

terperinci yang bergantung kepada magnetik, ultrasonik dan radiografi. Maka, teknik

NDE boleh digunakan untuk melaksanakan penilaian keatas bentuk-bentuk objek ferus

tanpa mengubah ciri-cirinya secara kekal. Teknik NDE yang digunakan dalam tesis ini

untuk penilaian bentuk-bentuk adalah berdasarkan ciri magnetik objek-objek ferus.

Tesis ini menghuraikan pembangunan prototaip Sistem Pengimejan Magnetik Mudah

Alih dengan teknik NDE untuk mengkaji bentuk objek ferus. Sistem Pengimejan

Magnetik Mudah Alih ini mampu untuk mengesan bentuk objek ferus di bawah

permukaan melalui teknik pengimejan magnetik yang dicadangkan dalam penyelidikan.

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Pengimejan magnetik untuk bentuk objek ferus dicapai melalui perlaksanaan plot kontur

2-D dengan susunan matrik 2-D isyarat voltan dorongan, VH dan medan magnetik, B.

Operasi Sistem Pengimejan Magnetik Mudah Alih adalah berdasarkan prinsip Ujian

Kebocoran Fluk Magnetik (MLFT) yang dilaksanakan pada permukaan bentuk objek

ferus. Apabila sistem melalui objek ferus, magnet kekal pada sistem akan memagnetkan

objek ferus. Objek ferus yang dimagnetkan akan membentuk litar magnetik dengan

magnet kekal, maka, gelung tertutup dibentuk untuk pengaliran fluk magnet, m.

Susunan pengesan Hall 1-D pada sistem didedahkan kepada medan magnet, B yang

dihasilkan daripada pengaliran fluk magnet, m dari magnet kekal ke bahan

ferromagnetik. Susunan pengesan Hall 1-D yang terdiri daripada pengesan Hall keadaan

pepejal linear digunakan untuk mengesan medan magnet, B dan menterjemahkannya

kepada isyarat voltan dorongan Hall, VH. Isyarat voltan dorongan Hall, VH dari susunan

pengesan Hall 1-D membina susunan matrik 2-D yang digunakan untuk pengimejan

magnetik.

Akhirnya, prototaip Sistem Pengimejan Magnetik Mudah Alih telah ditunjukkan. Di

samping itu, parameter-parameter untuk mengkaji prestasi Sistem Pengimejan Magnetik

Mudah Alih yang telah dikenal pasti termasuk saiz spesimen untuk penilaian, kelajuan

sistem dan ketebalan permukaan bukan ferromagnetik di atas objek-objek ferus. Maka,

hasil-hasil eksperimen untuk mengkaji pretasi Sistem Pengimejan Magnetik Mudah Alih

telah dibentangkan dalam tesis ini. Dalam bahagian pertama, ia membentangkan

keupayaan sistem dalam memaparkan bentuk-bentuk objek ferus dengan imej magnetik.

Tambahan pula, peningkatan keatas pengimejan magnetik untuk bentuk-bentuk objek

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ferus telah dicadangkan dengan mengambil nilai mutlak isyarat voltan dorongan, |VH|

dan medan magnetik, |B|. Dalam bahagin kedua, hasil eksperimen membentangkan

keupayaan sistem untuk memaparkan bentuk-bentuk objek ferus melalui peningkatan

keatas teknik pengimejan magnetik. Dalam bahagian ketiga, kesan jurang serenjang ke

atas ketepatan Sistem Pengimejan Magnetik Mudah Alih dalam penilaian bentuk telah

dikaji. Berdasarkan keputusan eksperimen, jurang serenjang yang dioptimumkan untuk

penilaian bentuk adalah pada 10mm.

Dalam ringkasan, Sistem Pengimejan Magnetik Mudah Alih ini terbukti mampu untuk

memaparkan bentuk-bentuk objek ferus terbenam di bawah permukaan bukan

ferromagnetik.

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ACKNOWLEDGEMENT

First of all, I would also like to express my deepest appreciation and gratitude to my

supervisor, Assoc. Prof. Dr. Noshisam Misron, who has constantly contributed countless

hours and interest in providing ideas and suggestion to my research. His valuable ideas

enable me to complete my post-graduate studies within 2 years.

A part from that, my appreciation also extends to the members of supervisory committee

including Assoc. Prof. Dr. Mohd. Hamiruce Marhaban and Dr. Suhaidi Shafie. Their

valuable comments and suggestions throughout the duration of my research are very

useful. Besides, they are also very resourceful for seeking advice whenever I

encountered roadblocks during my research.

Besides, my great appreciation also goes to fellow post-graduate students Raja Nor

Firdaus and Shuhairi for their endless help and assistant in getting components and parts

throughout the duration of my post-graduate studies. Without their help, it would be

difficult for me to complete my post-graduate studies within these two years.

Last but not least, my greatest appreciation goes to my fiancé and both my beloved

parents for their encouragement and support throughout the duration of my post-

graduate studies. Without their encouragement, it wouldn’t be possible for me to

complete my post-graduate studies while still working in Intel Malaysia.

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I certified that a Thesis Examination Committee has met on 27 February 2012 to

conduct the final examination of Ng Wei Shin on his thesis entitled “Development of

Mobile Magnetic Imaging System Based on 1-D Hall Sensor Array” in accordance with

the Universities and University Colleges Act 1971 and the Constitution of the Universiti

Putra Malaysia [P.U.(A) 106] 15 March 1998. The committee recommends that the

student be awarded the Master of Science.

Members of the Thesis Examination Committee were as follow:

Maryam binti Mohd Isa, PhD

Senior Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Mohd Nizar bin Hamidon, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Internal Examiner)

Roslina binti Sidek, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Internal Examiner)

Nasrudin bin Abdul Rahim, PhD

Professor

Faculty of Engineering

University of Malaya

(External Examiner)

___________________________________

SEOW HENG FONG, PhD

Professor and Deputy Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfillment of the requirement for the degree of Master of Science. The

members of the Supervisory Committee were as follow:

Norhisam Misron, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Mohd Hamiruce Marhaban, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Member)

Suhaidi Shafie, PhD

Senior Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Member)

___________________________________

BUJANG BIN KIM HUAT, PhD

Professor and Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which

have been duly acknowledged. I also declare that it has not been previously, and is not

concurrently, submitted for any other degree at Universiti Putra Malaysia or at any other

institutions.

_____________________________

NG WEI SHIN Date: 27 February 2012

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TABLE OF CONTENTS

Page

ABTRACT

ABSTRAK

ACKNOWLEDGEMENT

APPROVAL

DECLARATION

LIST OF FIGURES

LIST OF TABLES

LIST OF ABBREVIATION

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v

viii

ix

xi

xiv

xviii

xix

CHAPTER

I INTRODUCTION

1.1 Problem Statement

1.2 Objectives of Research

1.3 Scope of Research

1.4 Thesis Outline

1

3

4

5

6

II

LITERATURE REVIEW

2.1 Overview of Magnetic Circuit

2.1.1 Magnetic Field

2.1.2 Magnetic Flux

2.2 Overview of Hall Sensor

2.2.1 Hall Effect Phenomenon in Semiconductor

2.2.2 Basics of Hall Effect Sensor

2.3 Advantages of Hall Effect Sensor

2.4 Overview of Embedded Device Design

2.4.1 Microcontroller

2.4.2 Analog Multiplexer

2.4.3 Universal Serial Bus Communication

Protocol

2.5 Related Research on Non-destructive Evaluation

2.6 Related Research on Signals Array Processing

Hardware

2.7 Summary

8

8

10

12

15

16

17

20

22

23

25

27

30

36

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III

METHODOLOGY

3.1 Principle of Operation for Mobile Magnetic Imaging

System

3.1.1 Detection of Magnetic Field Perturbation

3.1.2 Construction of 2-Dimensional Hall Sensor

Signals Array Matrix

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3.1.3 Visualization of the Shapes of Ferrous

Objects with Magnetic Images

3.2 Overview of Research Methodology

3.3 Development of Hall Sensor Array System

3.3.1 Design of Signals Sensing Unit

3.3.2 Design of Signals Acquisition Unit

3.3.3 Design of Signals Processing Unit

3.4 Limitation of Mobile Magnetic Imaging System

3.5 Experimental Setup

3.6 Summary

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55

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IV

RESULTS AND DISCUSSIONS

4.1 The Prototype of Mobile Magnetic Imaging System

4.2 Performance Parameters of Mobile Magnetic

Imaging System

4.3 Specimens for Experiments

4.4 Magnetic Imaging of Ferrous Specimens

4.4.1 Magnetic Imaging with Induced Voltage for

Ferrous Specimens

4.4.2 Magnetic Imaging with Induced Magnetic

Field for Ferrous Specimens

4.5 Improvement on Magnetic Imaging Technique of

Ferrous Specimens

4.5.1 Magnetic Imaging with Absolute Induced

Voltage for Ferrous Specimens

4.5.2 Magnetic Imaging with Absolute Induced

Magnetic Field for Ferrous Specimens

4.6 Magnetic Imaging of Actual Ferrous Objects

4.7 Analysis on Effect of Perpendicular Gap Towards

Accuracy of Magnetic Imaging

4.8 Summary

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V

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions

5.2 Recommendations

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REFERENCES

APPENDICES

LIST OF PUBLICATIONS

BIODATA OF STUDENT

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119

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