Design Of A Low Cost Accelerometer Measuring Ambient Vibration Using Piezoelectric Devices.
i
DESIGN OF A LOW COST ACCELEROMETER MEASURING AMBIENT
VIBRATION USING PIEZOELECTRIC DEVICES
MUHAMAD HAFFIZ BIN MOHD RADZI
This Report Is Submitted In Partial Fulfillment Of Requirement For The Bachelor
Degree Of Electronic Engineering (Industrial Electronics)
Faculty of Electronics and Computer Engineering
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
June 2013
ii
iii
DECLARATION
“I hereby declare that this report entitle Design of a Low Cost Accelerometer
Measuring Ambient Vibration Using Piezoelectric Devices is result from my own
work and experiment except for quotes as cited in the references”.
Signature
:
Author
: Muhamad Haffiz Bin Mohd Radzi
Date
:
iv
APPROVAL
“I hereby declare that I have read this project report and in my opinion this report is
sufficient in term of the scope and quality for the award of Bachelor of Electronic
Engineering (Industrial Electronics) with honours”.
Signature
:
Name
: Dr. Kok Swee Leong
Date
:
v
DEDICATION
Special dedication to people that I love most, I would like to present my project
work to my family in their support and moral since I learn from standard one until now,
my lovely mother and my supporting father. The project work now is a gift that I have
design and hope it will be useful to people. Not forgetting also to give special thanks to
my brothers and sisters that always gives me their support and happiness.
Muhamad Haffiz B. Mohd Radzi
2013
vi
ACKNOWLEDGEMENT
First and foremost, praise be to Allah for His willingness, giving me this
opportunity, the patience and the strength to complete my final year project. The final
year project is not complete without this thesis. Working on this project has been a
wonderful and often overwhelming experience. It is hard to say after all the challenges
and difficulties that I had by myself which has been the real learning experience with
how to write proposals, papers, work in group, stay up until the bird and rooster start
singing, and stay focus in doing work. From the beginning of the project through all
difficulties until my project complete, I am indebted to many people for making the time
working on my project. It is unforgettable experience that I ever had.
First of all, I am deeply grateful to my supervisor Dr. Kok Swee Leong. Your
guidance has been real pleasure to me, with knowledge and excitement. You have been
a steady influence throughout my project, you have oriented and supported me with
promptness and care, and have always been patient and encouraging in time of new idea
and difficulties; you have listened to my ideas and discussions with you frequently led to
key insights. You have ability to select and approach compelling research problems,
your high scientific standards and your smart work set an example. I learned a lot from
you about research, how to tackle new problem and to develop techniques to solve them.
I admire your ability to balance research interests and personal pursuits. Overall you
made me feel a friend, which I appreciate from my heart.
In meantime, I am very grateful to my project panels for insightful comments in
my project, their support and motivation. A special thanks to Faculty of Electronic and
Computer Engineering for organizing the INOTEK competition. I had gained much
knowledge from other student’s projects. I am also indebted to my members of making
researcher group that I had the pleasure to work with. Special thanks to my friends for
moral support and sharing ideas in this project either direct or indirect way. Thanks to all
of you. This project would not happen without your support.
vii
ABSTRACT
Vibration and shock are present in everywhere. It may be generated and
transmitted by machine tools, human body and buildings. An accelerometer is a device
with sensor that measure vibration or acceleration of a motion structure. In this report we
look at issues related with designing and developing a low cost accelerometer measuring
ambient vibration by using piezoelectric devices. We survey existing technique and
technology of accelerometer. However, these accelerometers do not fulfill the
constraints imposed by people in term of cost and its performances. Additional
constraint that we impose by using piezoelectric cantilever is hard to be integrated. In
this project, the low cost accelerometer consists of piezoelectric sensor and charge
amplifier. The charge amplifier is constructed and signal output is analyzed. The
piezoelectric electric sensor element made up by PZT material and with physical size
(0.51mm × 3.2mm × 31.8mm). The use of charge amplifier to amplify the voltage output
from piezoelectric accelerometer. At the end of this project, the expected outcomes are
analyzing a cantilever-based accelerometer which can be used to measure vibration
acceleration level and frequency.
viii
ABSTRAK
Getaran dan kejutan wujud di merata tempat. Ia boleh dijana dan dihantar oleh
alat-alat mesin, badan manusia dan bangunan. Pengukur pecutan adalah satu alat dengan
peranti yang mengukur getaran atau pecutan struktur pegerakan. Dalam laporan ini kita
melihat isu-isu yang berkaitan dengan merekabentuk dan mencipta alat pengukur
pecutan kos rendah yang mengukur getaran sekeliling dengan menggunakan peranti
piezoelektrik. Kami meninjau teknik yang sedia ada dan teknologi pengukur pecutan.
Walau bagaimanapun, pecutan ini tidak memenuhi kekangan yang dikenakan oleh orang
ramai dalam bentuk kos dan prestasinya. Tambahan pula, kekangan yang kita timbulkan
adalah dengan menggunakan julur piezoelektrik amat sukar untuk digabungkan. Dalam
projek ini, pecutan kos rendah terdiri daripada alat peranti piezoelektrik, dan penguat
caj. Penguat caj dibina dan keluaran isyarat dianalisa. Elemen sensor piezoelektrik pula
terdiri oleh bahan PZT dengan saiz fizikal (0.51mm × 3.2mm × 31.8mm). Penggunaan
penguat caj adalah untuk menguatkan keluaran voltan dari pecutan piezoelektrik. Pada
akhir projek ini, hasil yang dijangkakan adalah menganalisis pecutan berasaskan julur
yang boleh digunakan untuk mengukur tahap kelajuan getaran dan kekerapan.
ix
CONTENTS
CHAPTER
1
SUBJECT
PAGE
PROJECT TITLE
i
VERIFICATION
ii
DECLARATION
iii
APPROVAL
iv
DEDICATION
v
ACKNOWLEDGMENT
vi
ABSTRACT
vii
ABSTRAK
viii
CONTENTS
ix
LIST OF TABLES
xiii
LIST OF FIGURES
xiv
LIST OF ABBREVIATION
xvi
LIST OF APPENDIX
xvii
INTRODUCTION
1
1.1 OVERVIEW
1
1.2 BACKGROUND
2
1.3 PROBLEM STATEMENT
4
1.4 OBJECTIVES
5
1.5 SCOPE OF WORK
6
1.6 SIGNIFICANT CONTRIBUTION
7
1.7 PROJECT OUTLINES
8
x
2
LITERATURE REVIEW
9
2.1 OVERVIEW
9
2.2 BACKGROUND STUDY
10
2.3 PIEZOELECTRICITY
11
2.4 PIEZOELECTRIC MATERIAL
12
2.5 PIEZOELECTRIC PRINCIPLE
12
2.5.1 Piezoelectric disk
3
13
2.6 APPLICATION
14
2.7 ACCELEROMETER
14
2.8 ACCELEROMETER DESIGN
16
2.8.1 Interface Circuit
16
2.8.2 Charge Amplifier
17
2.8.3 Frequency Response
20
METHODOLOGY
21
3.1 OVERVIEW
21
3.2 PROJECT METHODOLOGY
22
3.3 LITERATURE STUDIES
24
3.4 SOFTWARE IMPLEMENTATION
24
3.4.1 Sensor Model
25
3.4.2 Charge Amplifier Model
26
3.4.3 Overall Circuit Model
26
3.4.4 PCB Design and Implementation
28
3.4.5 Program Implementation
30
3.5 EXPERIMENTAL SETUP EQUIPMENT
3.5.1 Power Supply
31
31
xi
3.5.2 Function generator
32
3.5.3 Oscilloscope
33
3.5.4 Vibration Generator
33
3.5.5 Piezoelectric Cantilever
34
3.6 EXPERIMENTAL SETUP PROCEDURE
3.6.1 Frequency and G-level
3.7 HARDWARE IMPLEMENTATION
4
35
36
38
3.7.1 PCB Fabrication
39
3.7.2 Drilling
40
3.7.3 Soldering
41
3.7.4 Packaging
41
3.8 TESTING
42
3.9 TROUBLESHOOTING
42
RESULT AND ANALYSIS
43
4.1 OVERVIEW
43
4.2 OUTPUT VOLTAGE MEASUREMENT FROM
PIEZOELECTRIC TERMINALS
44
4.3 EXPERIMENTAL RESULTS FROM
CHARGE AMPLIFIER CIRCUIT
45
4.4 SIMULATION RESULTS AND ANALYSIS
50
4.5 PRACTICE APPROACH ANALYSIS
52
4.6 CONCLUSION
57
xii
5
CONCLUSION AND RECOMMENDATION
57
5.1 OVERVIEW
57
5.2 CONCLUSIONS
58
5.3 RECOMMENDATION
58
REFERENCES
59
xiii
LIST OF TABLES
TABLE
TITLE
PAGE
A.2
Pin Configuration Descriptions
63
A.3
Absolute Maximum ratings
63
A.5
Filter Capacitor Selection, CX, CY, and CZ
65
A.6
Estimation of Peak-to-Peak Noise
66
A.7
Specifications of ADXL 335
67
B.2
Absolute Maximum Ratings of LM 741
69
B.4
Electrical Characteristic of LM 741
70
of ADXL 335
xiv
LIST OF FIGURES
FIGURE
TITLE
PAGE
1.1
Block diagram of the low cost accelerometer
7
2.1
Piezoelectric disc effect with basic calculation
13
2.2
The stress on the piezoelectric
15
2.3
The equivalent circuit for a piezoelectric sensor
17
2.4
The charge amplifier circuit for a piezoelectric sensor
18
2.5
The frequency response curve
20
3.1
The flow chart of the project development
23
3.2
The flow chart model by software simulation
25
3.3
The design model of piezoelectric sensor
25
3.4
The design model of charge amplifier circuit
26
3.5
The overall circuit model
27
3.6
The output voltage of overall circuit model
27
3.7
The ISIS schematic design of charge amplifier
28
3.8
The ARES layout design of charge amplifier
28
3.9
The ISIS schematic design model of low cost accelerometer
29
3.10
The ARES layout model of low cost accelerometer
29
3.11
The 3D Visualization model
30
3.12
The power supply
31
3.13
The function generator
32
3.14
The oscilloscope
33
3.15
The vibration generator
34
3.16
The piezoelectric cantilever
34
xv
3.17
The experimental setup for piezoelectric cantilever
35
3.18
Accelerometer ADXL 335
37
3.19
The experimental setup for ADXL 335
37
3.20
The frequency response of ADXL 335
38
3.21
The component on breadboard
38
3.22
The PCB fabrication
40
3.23
The press drilling machine with twist drill
40
3.24
The packaging of project
42
4.1
The output voltage measurement from piezoelectric terminals
44
4.2
The voltage signal of the piezoelectric terminals
45
4.3
The output voltage from the piezoelectric with 0.2 g
46
4.4
The output voltage from the piezoelectric with 0.4 g
46
4.5
The output voltage from the piezoelectric with 0.6 g
47
4.6
The output voltage from the piezoelectric with 0.8 g
47
4.7
The output voltage from the piezoelectric with 1.0 g
48
4.8
The overall output voltage from piezoelectric with g-level
49
4.9
The linear response of design accelerometer
49
4.10
The design circuit via Multisim8
50
4.11
The simulation result from Multisim8 software
51
4.12
The analysis of output voltage for frequency, 100Hz
53
4.13
The analysis of output voltage for frequency, 200Hz
53
4.14
The analysis of output voltage for frequency, 300Hz
54
4.15
The analysis of output voltage for frequency, 400Hz
54
4.16
The analysis of output voltage for frequency, 500Hz
55
4.17
The analysis of output voltage for frequency, 700Hz
55
4.18
The analysis of output voltage for frequency, 800Hz
56
A.1
Pin Configuration ADXL 335
62
A.4
Schematic Block Diagram of ADXL 335
64
B.1
Pin Configuration LM 741
68
B.3
Schematic Diagram of LM 741
69
xvi
LIST OF ABBREVIATION
Acronym
Definition
AC
Alternating Current
ADXL 335
3-axis accelerometer
ADC
Analog to Digital Converter
BW
Bandwidth
DC
Direct Current
DNA
Deoxyribonucleic acid
FeCl36H2O
Ferric Chloride
G-level
Ground vibration level
IEEE
Institute of Electrical and Electronic Engineers
LCD
Liquid Crystal Display
LED
Light Emitting Diode
MEMS
Micro-Electro Mechanical Systems
NaOH
Sodium Hydroxide
OP-AMP
Operational Amplifier
PCB
Print Circuit Board
PWM
Pulse Width Modulation
PVDF
Polyvinylidene fluoride
PZT
Lead-Zirconate-Titanate
RoHS
Restriction of Hazardous Substances
UV
Ultraviolet
VO
Voltage Output
VS
Voltage Source
WEEE
Waste Electrical and Electronic Equipment
xvii
LIST OF APPENDIX
NO
TITLE
PAGE
A
ADXL 335
62
B
LM741 Operational Amplifier
68
1
CHAPTER 1
INTRODUCTION
1.1 Overview
This chapter will be briefly explained the background of this project. Starting with
background of the project, that is why this is chosen. Later, this chapter will also cover
about the problem statement that brings to idea to realize this project. Other parts of this
chapter will also discussing about the objectives that are the solution to overcome the
problem in the project. Scope of the project related to the limitations of this project due
to achieve the objectives of the project. Lastly, the significant contribution of this project
will be discussed in this chapter.
2
1.2 Background
Shock and vibration are present in all areas of our daily lives. It may be transmitted
and generated by machine-tools, turbines, motor, towers, bridges, and even by the
human body. Vibration and shock also may desirable, disturbing and even destructive. It
depends on the place and what type of source of vibration that occurs. In 1880,
piezoelectricity was discovered by Jacques Curie and Pierre Curie and the inverse
phenomenon named the converse piezoelectric effect [6]. There are several types of
accelerometer in measuring vibration such as piezoresistive, piezocapacitive, geophone
and others. The piezoceramic accelerometers are the better choice at low frequencies and
low acceleration. The piezoelectric accelerometers are wide accepted as the best choice
for measure absolute vibration in all areas [3]. There are several important advantages of
piezoelectric sensor compared to the other types of sensors such as: extremely wide
dynamic range, excellent linearity over the dynamic range, low output noise that suitable
for shock or vibration measurement as well as for almost imperceptible vibration, wide
frequency range that can be measured at very high frequencies, self-generating mean no
external power required, compact yet highly sensitive, no moving part – no wear, great
variety models available for any purpose and the integration of output signal
(acceleration signal) can provides velocity and displacement [4].
Piezoelectric sensors are most popular to be versatile tools for measurement of
various processes. The piezoelectric sensor is devices that use the piezoelectric effect to
measure acceleration, pressure, force and strain by converting mechanical motion to an
electric charge. For purpose of an accelerometer, piezoelectric material can be
categorized into two: quartz and PZT. The first one is single crystal material usually
quartz. It is a natural piezoelectric material that never loses piezoelectric properties.
These materials have a long life span in terms sensitivity. Quartz is more widely used in
sensing applications. In order to have higher piezoelectric constant (sensitivity) than
quartz, the ceramic materials are more low cost and inexpensive to produce an
accelerometer. This is other materials is ceramic material normally called ferroelectric
materials. It found to have ability to become “magnet” but some can made into
3
piezoelectric ceramic. There are several ceramic use as piezoelectric ceramic such as
barium titanate, lead-zirconate-titanate, lead metaniobate, and other material whose
composition is considered proprietary by the company responsible in their development.
Lead-Zirconate-Titanate (PZT) is piezoelectric ceramic used in most industrial
transducers [1][2].
An accelerometer is an electromechanical device that measures proper acceleration,
which is the acceleration it experiences relative to freefall and the acceleration force felt
by people or objects. This acceleration act like constant force of gravity pulling the feet,
or it could be dynamic caused by moving or vibrating the accelerometer. These
accelerations are popularly measured in term of g-force [23]. An accelerometer at rest of
the surface of the earth will measure an acceleration
straight upwards
due to its weight. Accelerometers are also available that can measure acceleration in one,
two or three orthogonal axes used to detect the magnitude and direction of the proper
acceleration. It is typically used in one of three modes: As an inertial measurement of
position and velocity; As a vibration or shock sensor; As a sensor of inclination, tilt, or
orientations in 2 or 3 dimensions, as referenced from the acceleration of gravity
[16].
The important specification of an accelerometer for a given application is its type of
output. There are two types of output accelerometer: analog and digital. Analog
accelerometer output a constant variable voltage that depends on the amount of
acceleration applied. Digital accelerometer output a variable frequency wave, a method
known as pulse-width modulation (PWM) [14]. There are many different way to make
an accelerometer. Several accelerometers use the piezoelectric effect they contain
microscopic crystal structure that get stressed by accelerative forces, which cause a
voltage to be generated. Another ways to do it are by sensing changes in capacitance [3].
Accelerometer can be used to measure vibration on vehicles, machines, buildings, and
safety installations. They also can be used to measure seismic activity, biological
sciences, dynamic distance and others.
4
In attempt to design a low cost accelerometer measuring ambient vibration using
piezoelectric device by analyzing a cantilever-based accelerometer which can be used to
measure vibration sources and develop an accelerometer. The material usage is
piezoelectric material that is PZT. The physical cantilever size is (0.51mm × 3.2mm ×
31.8mm). Piezoelectric accelerometer has to be operated more than 1 kHz and measure
ambient vibration less than 2 g-level. The signal produced under vibration excitation at
low frequency is too small and high impedance. To overcome this problem the charge
amplifier is needed to amplify the value of voltage. Then, the output signal can be
measure through oscilloscope. For further addition for this project, by using analog to
digital converter to convert the signal in term of digital and through microcontroller the
LCD will display the output value.
1.3 Problem Statement
There are recent research in piezoelectric sensor and research of ambient vibration
especially in area of developing and fabrication of accelerometer. However, there is only
a little information that can be obtained from the literature with respect to characteristic
of vibration such as frequency, amplitude, and acceleration. From previous research (A.
Carlosena, 2005) [13]; based on characteristic of piezoelectric cantilever accelerometer,
to have a good accelerometer the frequency response of vibration has to be linear. The
normal response of an accelerometer is nonlinear. The goal of this project is to design a
low cost accelerometer measuring ambient vibration using piezoelectric device that
fulfills the constraint imposed by the people. The problem is the accelerometers are
expensive due to its performances. By knowing exactly the characteristics of ambient
vibration source, material and frequency that we tend to use, we may able to identify
which the type of accelerometer that can work best and suit to the vibration source. In
this scenario, we want to design a low cost accelerometer using piezoelectric that can be
mounted on machine surface or application that vibrate for purpose of its periodical
5
parameter monitoring. Hence, we need to know the characteristic of the vibration source
that we tend to place at, which is the machine or vibrate application in lab. It is primary
importance for this process to work well on frequency range random acceleration data,
which is the type of data generated by the ambient vibration. In addition, the filtering
effect to reduce noise of the signal and filter the signal. In this project is using
piezoelectric cantilever for conversion of the mechanical motion into an electrical signal
produces a current and voltage value. In other to do this experiment, the problem are low
sensitivity and the signal too small that usually in the range of few micro-amps for
electric current and the voltage is mile-volt from previous research work (Levinzon,
2005) [20]. Therefore, a charge amplifier act as integrator is needed to detect the signal
and make the signal high sensitivity. The integrator make the signal emphasizes the
frequency data to get acceleration signal. By having a summary of data for the ambient
vibration that we test, we can design a low cost accelerometer measuring ambient
vibration using piezoelectric device.
1.4 Objectives
The objectives of this project are:
To design a low cost accelerometer measuring ambient vibration using
piezoelectric device.
To construct a PCB of a charge amplifier for the piezoelectric sensor.
To analyze the output signal from piezoelectric device.
6
1.5 Scope of Work
First of all, we study the characteristic of piezoelectric and vibration. The scopes or
limitations of this project in order to achieve the objectives of the project by designing a
low cost accelerometer measuring ambient vibration using piezoelectric device are
specification of the project and the cost of the project. The laboratory is the suitable
place to test the product and analyze all of factor that affects the low cost accelerometer.
The important specification of the project is to get a piezoelectric cantilever work an
accelerometer by using low cost material usage and easily available piezoelectric
materials is ceramics (PZT). The physical size of MEMS devices is about (0.51mm ×
3.2mm × 31.8mm) to be mounted as a piezoelectric cantilever based sensor. The
piezoelectric cantilevers have to be operated as low frequency ≥ 1 kHz. Identify the
range of signal and use charge amplifier to amplify the signal in order to emphasize the
signal and to get a linear output with an error around 5%. In other to achieve others
objectives are to construct a PCB of charge amplifier for piezoelectric sensor, analyze
the signal and develop the low cost accelerometer. Before construct the circuit, use
Multisim8 software to stimulate the charge amplifier circuit and use oscilloscope to
analyze the frequency response. Then, construct and test the entire component that use in
produce accelerometer on the bread board. If it all component good in condition,
proceed with built in electronic microcontroller and construct display. Structure the
design of accelerometer follow by the electronic designs for the project with fabricates
PCB of charge amplifier with op-amp ICs circuit. The vibration level (g-level) for test
the accelerometer is less than 2 g (1 g = 9.81ms-2) by using vibration generator to vibrate
the piezoelectric cantilever. Before the project complete, we must analyze the several
factors that affect the low cost accelerometer. After the circuit complete constructed, we
must test the circuit to see the performance of the circuit and do some additional or
reconstruct if have problem with the circuit. Then, proceed with the packaging of the
low cost accelerometer.
7
1.6 Significant Contribution
The low cost accelerometer consists of piezoelectric sensor (ceramic), charge
amplifier, filter, ADC, microcontroller and display. In this project, the major
contribution is to analyze the output signal from a piezoelectric cantilever as a vibration
sensor element which is considered as a low cost accelerometer able to measure ambient
vibration sources with levels ≤ 2 g at higher than resonant frequency ≥
. The low
cost accelerometer is designed and developed using piezoelectric cantilever size
(0.51mm x 3.2mm x 31.8mm). This piezoelectric accelerometer is designed to be as a
cantilever when excited by external vibration sources and low cost prototype
accelerometer. Figure 1.1 shows the block diagram of the complete low cost
accelerometer system. However, the focus on this system is as shown a dotted box
consists of the piezoelectric sensor, charge amplifier and filter.
Piezoelectric
Sensor
Charge
Amplifier
Filter
Analog to
Digital
Converter
Micro
controller
Figure 1.1: Block diagram of the low cost accelerometer.
Display
DESIGN OF A LOW COST ACCELEROMETER MEASURING AMBIENT
VIBRATION USING PIEZOELECTRIC DEVICES
MUHAMAD HAFFIZ BIN MOHD RADZI
This Report Is Submitted In Partial Fulfillment Of Requirement For The Bachelor
Degree Of Electronic Engineering (Industrial Electronics)
Faculty of Electronics and Computer Engineering
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
June 2013
ii
iii
DECLARATION
“I hereby declare that this report entitle Design of a Low Cost Accelerometer
Measuring Ambient Vibration Using Piezoelectric Devices is result from my own
work and experiment except for quotes as cited in the references”.
Signature
:
Author
: Muhamad Haffiz Bin Mohd Radzi
Date
:
iv
APPROVAL
“I hereby declare that I have read this project report and in my opinion this report is
sufficient in term of the scope and quality for the award of Bachelor of Electronic
Engineering (Industrial Electronics) with honours”.
Signature
:
Name
: Dr. Kok Swee Leong
Date
:
v
DEDICATION
Special dedication to people that I love most, I would like to present my project
work to my family in their support and moral since I learn from standard one until now,
my lovely mother and my supporting father. The project work now is a gift that I have
design and hope it will be useful to people. Not forgetting also to give special thanks to
my brothers and sisters that always gives me their support and happiness.
Muhamad Haffiz B. Mohd Radzi
2013
vi
ACKNOWLEDGEMENT
First and foremost, praise be to Allah for His willingness, giving me this
opportunity, the patience and the strength to complete my final year project. The final
year project is not complete without this thesis. Working on this project has been a
wonderful and often overwhelming experience. It is hard to say after all the challenges
and difficulties that I had by myself which has been the real learning experience with
how to write proposals, papers, work in group, stay up until the bird and rooster start
singing, and stay focus in doing work. From the beginning of the project through all
difficulties until my project complete, I am indebted to many people for making the time
working on my project. It is unforgettable experience that I ever had.
First of all, I am deeply grateful to my supervisor Dr. Kok Swee Leong. Your
guidance has been real pleasure to me, with knowledge and excitement. You have been
a steady influence throughout my project, you have oriented and supported me with
promptness and care, and have always been patient and encouraging in time of new idea
and difficulties; you have listened to my ideas and discussions with you frequently led to
key insights. You have ability to select and approach compelling research problems,
your high scientific standards and your smart work set an example. I learned a lot from
you about research, how to tackle new problem and to develop techniques to solve them.
I admire your ability to balance research interests and personal pursuits. Overall you
made me feel a friend, which I appreciate from my heart.
In meantime, I am very grateful to my project panels for insightful comments in
my project, their support and motivation. A special thanks to Faculty of Electronic and
Computer Engineering for organizing the INOTEK competition. I had gained much
knowledge from other student’s projects. I am also indebted to my members of making
researcher group that I had the pleasure to work with. Special thanks to my friends for
moral support and sharing ideas in this project either direct or indirect way. Thanks to all
of you. This project would not happen without your support.
vii
ABSTRACT
Vibration and shock are present in everywhere. It may be generated and
transmitted by machine tools, human body and buildings. An accelerometer is a device
with sensor that measure vibration or acceleration of a motion structure. In this report we
look at issues related with designing and developing a low cost accelerometer measuring
ambient vibration by using piezoelectric devices. We survey existing technique and
technology of accelerometer. However, these accelerometers do not fulfill the
constraints imposed by people in term of cost and its performances. Additional
constraint that we impose by using piezoelectric cantilever is hard to be integrated. In
this project, the low cost accelerometer consists of piezoelectric sensor and charge
amplifier. The charge amplifier is constructed and signal output is analyzed. The
piezoelectric electric sensor element made up by PZT material and with physical size
(0.51mm × 3.2mm × 31.8mm). The use of charge amplifier to amplify the voltage output
from piezoelectric accelerometer. At the end of this project, the expected outcomes are
analyzing a cantilever-based accelerometer which can be used to measure vibration
acceleration level and frequency.
viii
ABSTRAK
Getaran dan kejutan wujud di merata tempat. Ia boleh dijana dan dihantar oleh
alat-alat mesin, badan manusia dan bangunan. Pengukur pecutan adalah satu alat dengan
peranti yang mengukur getaran atau pecutan struktur pegerakan. Dalam laporan ini kita
melihat isu-isu yang berkaitan dengan merekabentuk dan mencipta alat pengukur
pecutan kos rendah yang mengukur getaran sekeliling dengan menggunakan peranti
piezoelektrik. Kami meninjau teknik yang sedia ada dan teknologi pengukur pecutan.
Walau bagaimanapun, pecutan ini tidak memenuhi kekangan yang dikenakan oleh orang
ramai dalam bentuk kos dan prestasinya. Tambahan pula, kekangan yang kita timbulkan
adalah dengan menggunakan julur piezoelektrik amat sukar untuk digabungkan. Dalam
projek ini, pecutan kos rendah terdiri daripada alat peranti piezoelektrik, dan penguat
caj. Penguat caj dibina dan keluaran isyarat dianalisa. Elemen sensor piezoelektrik pula
terdiri oleh bahan PZT dengan saiz fizikal (0.51mm × 3.2mm × 31.8mm). Penggunaan
penguat caj adalah untuk menguatkan keluaran voltan dari pecutan piezoelektrik. Pada
akhir projek ini, hasil yang dijangkakan adalah menganalisis pecutan berasaskan julur
yang boleh digunakan untuk mengukur tahap kelajuan getaran dan kekerapan.
ix
CONTENTS
CHAPTER
1
SUBJECT
PAGE
PROJECT TITLE
i
VERIFICATION
ii
DECLARATION
iii
APPROVAL
iv
DEDICATION
v
ACKNOWLEDGMENT
vi
ABSTRACT
vii
ABSTRAK
viii
CONTENTS
ix
LIST OF TABLES
xiii
LIST OF FIGURES
xiv
LIST OF ABBREVIATION
xvi
LIST OF APPENDIX
xvii
INTRODUCTION
1
1.1 OVERVIEW
1
1.2 BACKGROUND
2
1.3 PROBLEM STATEMENT
4
1.4 OBJECTIVES
5
1.5 SCOPE OF WORK
6
1.6 SIGNIFICANT CONTRIBUTION
7
1.7 PROJECT OUTLINES
8
x
2
LITERATURE REVIEW
9
2.1 OVERVIEW
9
2.2 BACKGROUND STUDY
10
2.3 PIEZOELECTRICITY
11
2.4 PIEZOELECTRIC MATERIAL
12
2.5 PIEZOELECTRIC PRINCIPLE
12
2.5.1 Piezoelectric disk
3
13
2.6 APPLICATION
14
2.7 ACCELEROMETER
14
2.8 ACCELEROMETER DESIGN
16
2.8.1 Interface Circuit
16
2.8.2 Charge Amplifier
17
2.8.3 Frequency Response
20
METHODOLOGY
21
3.1 OVERVIEW
21
3.2 PROJECT METHODOLOGY
22
3.3 LITERATURE STUDIES
24
3.4 SOFTWARE IMPLEMENTATION
24
3.4.1 Sensor Model
25
3.4.2 Charge Amplifier Model
26
3.4.3 Overall Circuit Model
26
3.4.4 PCB Design and Implementation
28
3.4.5 Program Implementation
30
3.5 EXPERIMENTAL SETUP EQUIPMENT
3.5.1 Power Supply
31
31
xi
3.5.2 Function generator
32
3.5.3 Oscilloscope
33
3.5.4 Vibration Generator
33
3.5.5 Piezoelectric Cantilever
34
3.6 EXPERIMENTAL SETUP PROCEDURE
3.6.1 Frequency and G-level
3.7 HARDWARE IMPLEMENTATION
4
35
36
38
3.7.1 PCB Fabrication
39
3.7.2 Drilling
40
3.7.3 Soldering
41
3.7.4 Packaging
41
3.8 TESTING
42
3.9 TROUBLESHOOTING
42
RESULT AND ANALYSIS
43
4.1 OVERVIEW
43
4.2 OUTPUT VOLTAGE MEASUREMENT FROM
PIEZOELECTRIC TERMINALS
44
4.3 EXPERIMENTAL RESULTS FROM
CHARGE AMPLIFIER CIRCUIT
45
4.4 SIMULATION RESULTS AND ANALYSIS
50
4.5 PRACTICE APPROACH ANALYSIS
52
4.6 CONCLUSION
57
xii
5
CONCLUSION AND RECOMMENDATION
57
5.1 OVERVIEW
57
5.2 CONCLUSIONS
58
5.3 RECOMMENDATION
58
REFERENCES
59
xiii
LIST OF TABLES
TABLE
TITLE
PAGE
A.2
Pin Configuration Descriptions
63
A.3
Absolute Maximum ratings
63
A.5
Filter Capacitor Selection, CX, CY, and CZ
65
A.6
Estimation of Peak-to-Peak Noise
66
A.7
Specifications of ADXL 335
67
B.2
Absolute Maximum Ratings of LM 741
69
B.4
Electrical Characteristic of LM 741
70
of ADXL 335
xiv
LIST OF FIGURES
FIGURE
TITLE
PAGE
1.1
Block diagram of the low cost accelerometer
7
2.1
Piezoelectric disc effect with basic calculation
13
2.2
The stress on the piezoelectric
15
2.3
The equivalent circuit for a piezoelectric sensor
17
2.4
The charge amplifier circuit for a piezoelectric sensor
18
2.5
The frequency response curve
20
3.1
The flow chart of the project development
23
3.2
The flow chart model by software simulation
25
3.3
The design model of piezoelectric sensor
25
3.4
The design model of charge amplifier circuit
26
3.5
The overall circuit model
27
3.6
The output voltage of overall circuit model
27
3.7
The ISIS schematic design of charge amplifier
28
3.8
The ARES layout design of charge amplifier
28
3.9
The ISIS schematic design model of low cost accelerometer
29
3.10
The ARES layout model of low cost accelerometer
29
3.11
The 3D Visualization model
30
3.12
The power supply
31
3.13
The function generator
32
3.14
The oscilloscope
33
3.15
The vibration generator
34
3.16
The piezoelectric cantilever
34
xv
3.17
The experimental setup for piezoelectric cantilever
35
3.18
Accelerometer ADXL 335
37
3.19
The experimental setup for ADXL 335
37
3.20
The frequency response of ADXL 335
38
3.21
The component on breadboard
38
3.22
The PCB fabrication
40
3.23
The press drilling machine with twist drill
40
3.24
The packaging of project
42
4.1
The output voltage measurement from piezoelectric terminals
44
4.2
The voltage signal of the piezoelectric terminals
45
4.3
The output voltage from the piezoelectric with 0.2 g
46
4.4
The output voltage from the piezoelectric with 0.4 g
46
4.5
The output voltage from the piezoelectric with 0.6 g
47
4.6
The output voltage from the piezoelectric with 0.8 g
47
4.7
The output voltage from the piezoelectric with 1.0 g
48
4.8
The overall output voltage from piezoelectric with g-level
49
4.9
The linear response of design accelerometer
49
4.10
The design circuit via Multisim8
50
4.11
The simulation result from Multisim8 software
51
4.12
The analysis of output voltage for frequency, 100Hz
53
4.13
The analysis of output voltage for frequency, 200Hz
53
4.14
The analysis of output voltage for frequency, 300Hz
54
4.15
The analysis of output voltage for frequency, 400Hz
54
4.16
The analysis of output voltage for frequency, 500Hz
55
4.17
The analysis of output voltage for frequency, 700Hz
55
4.18
The analysis of output voltage for frequency, 800Hz
56
A.1
Pin Configuration ADXL 335
62
A.4
Schematic Block Diagram of ADXL 335
64
B.1
Pin Configuration LM 741
68
B.3
Schematic Diagram of LM 741
69
xvi
LIST OF ABBREVIATION
Acronym
Definition
AC
Alternating Current
ADXL 335
3-axis accelerometer
ADC
Analog to Digital Converter
BW
Bandwidth
DC
Direct Current
DNA
Deoxyribonucleic acid
FeCl36H2O
Ferric Chloride
G-level
Ground vibration level
IEEE
Institute of Electrical and Electronic Engineers
LCD
Liquid Crystal Display
LED
Light Emitting Diode
MEMS
Micro-Electro Mechanical Systems
NaOH
Sodium Hydroxide
OP-AMP
Operational Amplifier
PCB
Print Circuit Board
PWM
Pulse Width Modulation
PVDF
Polyvinylidene fluoride
PZT
Lead-Zirconate-Titanate
RoHS
Restriction of Hazardous Substances
UV
Ultraviolet
VO
Voltage Output
VS
Voltage Source
WEEE
Waste Electrical and Electronic Equipment
xvii
LIST OF APPENDIX
NO
TITLE
PAGE
A
ADXL 335
62
B
LM741 Operational Amplifier
68
1
CHAPTER 1
INTRODUCTION
1.1 Overview
This chapter will be briefly explained the background of this project. Starting with
background of the project, that is why this is chosen. Later, this chapter will also cover
about the problem statement that brings to idea to realize this project. Other parts of this
chapter will also discussing about the objectives that are the solution to overcome the
problem in the project. Scope of the project related to the limitations of this project due
to achieve the objectives of the project. Lastly, the significant contribution of this project
will be discussed in this chapter.
2
1.2 Background
Shock and vibration are present in all areas of our daily lives. It may be transmitted
and generated by machine-tools, turbines, motor, towers, bridges, and even by the
human body. Vibration and shock also may desirable, disturbing and even destructive. It
depends on the place and what type of source of vibration that occurs. In 1880,
piezoelectricity was discovered by Jacques Curie and Pierre Curie and the inverse
phenomenon named the converse piezoelectric effect [6]. There are several types of
accelerometer in measuring vibration such as piezoresistive, piezocapacitive, geophone
and others. The piezoceramic accelerometers are the better choice at low frequencies and
low acceleration. The piezoelectric accelerometers are wide accepted as the best choice
for measure absolute vibration in all areas [3]. There are several important advantages of
piezoelectric sensor compared to the other types of sensors such as: extremely wide
dynamic range, excellent linearity over the dynamic range, low output noise that suitable
for shock or vibration measurement as well as for almost imperceptible vibration, wide
frequency range that can be measured at very high frequencies, self-generating mean no
external power required, compact yet highly sensitive, no moving part – no wear, great
variety models available for any purpose and the integration of output signal
(acceleration signal) can provides velocity and displacement [4].
Piezoelectric sensors are most popular to be versatile tools for measurement of
various processes. The piezoelectric sensor is devices that use the piezoelectric effect to
measure acceleration, pressure, force and strain by converting mechanical motion to an
electric charge. For purpose of an accelerometer, piezoelectric material can be
categorized into two: quartz and PZT. The first one is single crystal material usually
quartz. It is a natural piezoelectric material that never loses piezoelectric properties.
These materials have a long life span in terms sensitivity. Quartz is more widely used in
sensing applications. In order to have higher piezoelectric constant (sensitivity) than
quartz, the ceramic materials are more low cost and inexpensive to produce an
accelerometer. This is other materials is ceramic material normally called ferroelectric
materials. It found to have ability to become “magnet” but some can made into
3
piezoelectric ceramic. There are several ceramic use as piezoelectric ceramic such as
barium titanate, lead-zirconate-titanate, lead metaniobate, and other material whose
composition is considered proprietary by the company responsible in their development.
Lead-Zirconate-Titanate (PZT) is piezoelectric ceramic used in most industrial
transducers [1][2].
An accelerometer is an electromechanical device that measures proper acceleration,
which is the acceleration it experiences relative to freefall and the acceleration force felt
by people or objects. This acceleration act like constant force of gravity pulling the feet,
or it could be dynamic caused by moving or vibrating the accelerometer. These
accelerations are popularly measured in term of g-force [23]. An accelerometer at rest of
the surface of the earth will measure an acceleration
straight upwards
due to its weight. Accelerometers are also available that can measure acceleration in one,
two or three orthogonal axes used to detect the magnitude and direction of the proper
acceleration. It is typically used in one of three modes: As an inertial measurement of
position and velocity; As a vibration or shock sensor; As a sensor of inclination, tilt, or
orientations in 2 or 3 dimensions, as referenced from the acceleration of gravity
[16].
The important specification of an accelerometer for a given application is its type of
output. There are two types of output accelerometer: analog and digital. Analog
accelerometer output a constant variable voltage that depends on the amount of
acceleration applied. Digital accelerometer output a variable frequency wave, a method
known as pulse-width modulation (PWM) [14]. There are many different way to make
an accelerometer. Several accelerometers use the piezoelectric effect they contain
microscopic crystal structure that get stressed by accelerative forces, which cause a
voltage to be generated. Another ways to do it are by sensing changes in capacitance [3].
Accelerometer can be used to measure vibration on vehicles, machines, buildings, and
safety installations. They also can be used to measure seismic activity, biological
sciences, dynamic distance and others.
4
In attempt to design a low cost accelerometer measuring ambient vibration using
piezoelectric device by analyzing a cantilever-based accelerometer which can be used to
measure vibration sources and develop an accelerometer. The material usage is
piezoelectric material that is PZT. The physical cantilever size is (0.51mm × 3.2mm ×
31.8mm). Piezoelectric accelerometer has to be operated more than 1 kHz and measure
ambient vibration less than 2 g-level. The signal produced under vibration excitation at
low frequency is too small and high impedance. To overcome this problem the charge
amplifier is needed to amplify the value of voltage. Then, the output signal can be
measure through oscilloscope. For further addition for this project, by using analog to
digital converter to convert the signal in term of digital and through microcontroller the
LCD will display the output value.
1.3 Problem Statement
There are recent research in piezoelectric sensor and research of ambient vibration
especially in area of developing and fabrication of accelerometer. However, there is only
a little information that can be obtained from the literature with respect to characteristic
of vibration such as frequency, amplitude, and acceleration. From previous research (A.
Carlosena, 2005) [13]; based on characteristic of piezoelectric cantilever accelerometer,
to have a good accelerometer the frequency response of vibration has to be linear. The
normal response of an accelerometer is nonlinear. The goal of this project is to design a
low cost accelerometer measuring ambient vibration using piezoelectric device that
fulfills the constraint imposed by the people. The problem is the accelerometers are
expensive due to its performances. By knowing exactly the characteristics of ambient
vibration source, material and frequency that we tend to use, we may able to identify
which the type of accelerometer that can work best and suit to the vibration source. In
this scenario, we want to design a low cost accelerometer using piezoelectric that can be
mounted on machine surface or application that vibrate for purpose of its periodical
5
parameter monitoring. Hence, we need to know the characteristic of the vibration source
that we tend to place at, which is the machine or vibrate application in lab. It is primary
importance for this process to work well on frequency range random acceleration data,
which is the type of data generated by the ambient vibration. In addition, the filtering
effect to reduce noise of the signal and filter the signal. In this project is using
piezoelectric cantilever for conversion of the mechanical motion into an electrical signal
produces a current and voltage value. In other to do this experiment, the problem are low
sensitivity and the signal too small that usually in the range of few micro-amps for
electric current and the voltage is mile-volt from previous research work (Levinzon,
2005) [20]. Therefore, a charge amplifier act as integrator is needed to detect the signal
and make the signal high sensitivity. The integrator make the signal emphasizes the
frequency data to get acceleration signal. By having a summary of data for the ambient
vibration that we test, we can design a low cost accelerometer measuring ambient
vibration using piezoelectric device.
1.4 Objectives
The objectives of this project are:
To design a low cost accelerometer measuring ambient vibration using
piezoelectric device.
To construct a PCB of a charge amplifier for the piezoelectric sensor.
To analyze the output signal from piezoelectric device.
6
1.5 Scope of Work
First of all, we study the characteristic of piezoelectric and vibration. The scopes or
limitations of this project in order to achieve the objectives of the project by designing a
low cost accelerometer measuring ambient vibration using piezoelectric device are
specification of the project and the cost of the project. The laboratory is the suitable
place to test the product and analyze all of factor that affects the low cost accelerometer.
The important specification of the project is to get a piezoelectric cantilever work an
accelerometer by using low cost material usage and easily available piezoelectric
materials is ceramics (PZT). The physical size of MEMS devices is about (0.51mm ×
3.2mm × 31.8mm) to be mounted as a piezoelectric cantilever based sensor. The
piezoelectric cantilevers have to be operated as low frequency ≥ 1 kHz. Identify the
range of signal and use charge amplifier to amplify the signal in order to emphasize the
signal and to get a linear output with an error around 5%. In other to achieve others
objectives are to construct a PCB of charge amplifier for piezoelectric sensor, analyze
the signal and develop the low cost accelerometer. Before construct the circuit, use
Multisim8 software to stimulate the charge amplifier circuit and use oscilloscope to
analyze the frequency response. Then, construct and test the entire component that use in
produce accelerometer on the bread board. If it all component good in condition,
proceed with built in electronic microcontroller and construct display. Structure the
design of accelerometer follow by the electronic designs for the project with fabricates
PCB of charge amplifier with op-amp ICs circuit. The vibration level (g-level) for test
the accelerometer is less than 2 g (1 g = 9.81ms-2) by using vibration generator to vibrate
the piezoelectric cantilever. Before the project complete, we must analyze the several
factors that affect the low cost accelerometer. After the circuit complete constructed, we
must test the circuit to see the performance of the circuit and do some additional or
reconstruct if have problem with the circuit. Then, proceed with the packaging of the
low cost accelerometer.
7
1.6 Significant Contribution
The low cost accelerometer consists of piezoelectric sensor (ceramic), charge
amplifier, filter, ADC, microcontroller and display. In this project, the major
contribution is to analyze the output signal from a piezoelectric cantilever as a vibration
sensor element which is considered as a low cost accelerometer able to measure ambient
vibration sources with levels ≤ 2 g at higher than resonant frequency ≥
. The low
cost accelerometer is designed and developed using piezoelectric cantilever size
(0.51mm x 3.2mm x 31.8mm). This piezoelectric accelerometer is designed to be as a
cantilever when excited by external vibration sources and low cost prototype
accelerometer. Figure 1.1 shows the block diagram of the complete low cost
accelerometer system. However, the focus on this system is as shown a dotted box
consists of the piezoelectric sensor, charge amplifier and filter.
Piezoelectric
Sensor
Charge
Amplifier
Filter
Analog to
Digital
Converter
Micro
controller
Figure 1.1: Block diagram of the low cost accelerometer.
Display