piezoelectric mat
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ThesisTRANSCRIPT
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DESIGN AND SIMULATION OF ENERGY HARVESTING
PIEZOELECTRIC PUZZLE FLOOR MAT USING
PIEZOELECTRIC CRYSTALS
A thesis presented to the College of Engineering of
FEU – Institute of Technology
In partial fulfillment of the requirement for the
Degree of Bachelor of Science
In Electronics Engineering
By
Magluyan, Pamela Kim Donnelle G.
Capati, Aubrey Sharmaine M.
Postre, Raul Christian M.
Engr. Luigi Carlo M. De Jesus
Adviser
Engr. King Harold H. Recto
Faculty in Charge
January 2016
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Table of Contents
Page No.
Title Page i
Table of Contents ii
List of Tables iii
List of Figures iv
Chapter 1 Introduction 1
Background of the Study 1
Statement of the Problem 4
General Objective 5
Specific Objective 5
Scope and Delimitation 5
Significance of Study 7
Definition of Terms 8
Chapter 2 Review of Related Works and Literature 9
Review of Related Materials 9
Floor Mats 9
Rubber Sheets 10
Piezoelectric Transducer 11
Piezoelectric Crystals 11
Lithium-ion Battery 11
Full-Wave Rectifier 14
Bridge Full Wave Rectifier 14
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Step – up Chopper 16
Compression Springs 16
Working Theories 16
Energy Harvesting 16
Piezoelectricity 18
How Piezoelectric Effect Works 18
Frequency of Oscillation 19
Cascaded Operational Amplifier Circuit 19
Review of Related Works and Studies 20
Foreign Works and Studies 20
Japan Harnesses Energy from Footsteps 20
A Shoe-Embedded Piezoelectric Energy 22
Harvester for Wearable Sensors
Source of Vibration for Crystal Previous Work 24
Power Generating Sidewalk 24
Power Generating Boots or Shoes 24
Gyms and Workplaces 25
Mobile Keypad and Keyboards 25
Floor Mats, Tiles and Carpets 26
People Powered Dance Clubs 26
Piezoelectric Energy Harvesting 26
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Local Works and Studies 28
In-Wheel Piezoelectric Generator for 28
Lighting Application of Mining Trolleys
Energy-Harnessing Footwear Using 29
Combined Electromechanical And
Piezoelectric Transducers for Charging
Supercapacitors (2009 )
Power Generation for Remote Areas Utilizing 30
Piezoelectric Transducers Harnessing Wind and
Wave Energy (2011)
Chapter 3 Research Methodology 31
Conceptual Framework 31
Block Diagram 32
Schematic Diagram 33
Full-Wave Bridge Rectifier 34
Step-Up Chopper (DC/DC converter) 35
Lithium-ion Battery 35
PCB Layout 36
Flow Chart of Process 37
Test Population 39
Treatment of Data 39
Calculations for the number of trials 39
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Calculation for the Tolerance 40
Testing Procedure 41
Proposed Table for Test Results 41
Proposed Project 43
Ideal Set up 43
Design Considerations of Puzzle Floor Mat 43
References 49
Appendices
Appendix A Chi-Square Critical Values Table 52
Appendix B Bill of Materials 54
Appendix C Gantt Chart 55
Appendix D Average Weight of Students in 56
FEU-Institute of Technology
Appendix E Data of Average Students that Entered 60
the School Premises
Appendix F Consultation Sheet 64
iii
List of Tables
Figure No. Description Page No.
1 Specifications of Lithium-ion Battery 36
2 Proposed Table for Test Results 41
3 Specifications of Smaller Spring 46
4 Specifications of the Bigger Springs as a support 47
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List of Figures
Figure No. Description Page No.
1 Charging and discharging phenomena in Lithium Ion batteries 13
2 Bridge Full-Wave Rectifier 14
3 Commuters at the Tokyo station walk on a piezoelectric sheet 22
which generates electricity when pedestrians step on it
4 A Shoe-Embedded Piezoelectric Energy Harvester 23
for Wearable Sensor
5 Energy Harvested of Phase 1 and Phase II 28
6 Energy Harvesting Shoe 30
7 Conceptual Framework 31
8 Block Diagram 32
9 Circuit Diagram of the System 33
10 Full-Wave Bridge Rectifier 34
11 Lithium-ion Battery 35
12 PCB Layout 36
13 System Flowchart 37
14 Ideal Set up: A man stepping on the floor mat 43
15 Dimensions of the Puzzle Floor Mat 43
16 Top View of the Puzzle Floor Mat 44
17 Inner Part of the Puzzle Floor Mat 45
18 Comparison of design with respect to vibrations 48
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Chapter I
Introduction
1.1 Background of the Study
Technology has evolved and became more advanced over the past decades and
along with this, the sources of energy that can power up electronics became more
industrialized.
Most energy sources have been depleting due to a great demand from its
increasing population. It is a given fact that the country has been battling with energy
sources that would supply electricity. Manila and other cities had experienced black –
outs or power outages in earlier months of year 2015, specifically April to May because
of the shortage of supply of electricity [1]. Some of the energy sources like Malampaya
have been closed for operating due to weather or climate conditions.
The main energy sources which can be harvested are categorized in mechanical
energy from vibrations, thermal energy, solar energy, biomass and fossil fuels. Another
significant source of energy which is often overlooked is the human body. Human body
can generate a significant amount of energy through footsteps. The human waste foot
energy is being used to produce electricity which is a great evolution in electricity
generation. The average human can take 3,000 – 5,000 steps a day [2]. Some of the
energy wasted when human walks which is in the form of vibrations can be converted
into an electrical energy using Piezoelectric Crystals. Any form of vibration like
footsteps, heartbeats, etc. can generate electricity to activate electronic devices [3]. The
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concept of piezoelectricity can be applied as actuators, transducers, motors, and even
sensors wherein different kinds of materials are used like crystals and strips. The
harvesting of energy of a piezoelectric material is not affected by weather or climate
conditions. Piezoelectric materials generate energy through vibrations or pressure like
footsteps unlike energies from water, sun, wind and etc.
Piezoelectricity are massively used in foreign countries and even in the
Philippines. However, it is mainly used as a transducer in the Philippines. One example
is a microphone where it receives sound waves that are converted into electrical energy
with the use of Piezoelectric Crystals. Piezoelectric Crystals are also used in electric
cigarette lighter. Piezoelectricity has not been used as a large source of energy in the
Philippines. In Japan, piezoelectric floor tiles are used to operate the train – ticketing
systems. These floor tiles converts the vibrations of footsteps into electrical energy in
which the capacity of one footstep can provide enough electrical current to light two 60
– watts bulb for one second [4].
The mass of the person stepping on the floor mat has an effect regarding the
energy output and design consideration. If the person is heavy, the force on the floor mat
is much larger than a light person. On the other hand, the design of floor mat has its
limited weight capacity until it breaks. Using the sample data gathered by the researchers,
the average weight of a person in FEU – Institute of Technology is about 63 kilograms.
Through considering the materials that will be used on the project, the researchers were
able to compute the estimated maximum weight capacity of the floor mat which is 36,993
kilograms.
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Most existing piezoelectric energy harvesting floors used floor tiles. Floor tiles
usually provide a hard surface. Unlike floor mats that are usually made of cloth and
rubber which are soft. An impact is a high force or shock which is applied over a short
period of time once two or more bodies collide whether elastic or inelastic [5]. A theory
in Engineering Mechanics states that impact strength, expressed in amount of energy
absorbed before fracture, decreases per increase in the modulus of elasticity which means
stiff materials will have less impact strength than supple materials [5]. Soft surfaces like
floor mats can produce more oscillations.
Piezoelectric Floor Tiles used ceramic tiles that are heavier than Puzzle Floor Mat
which uses rubber sheets. The mass of the upper layer of the mat which is the rubber
sheets will produce more vibrations than the mass of the ceramic tile. The concept of
frequency of oscillation states that the frequency is inversely proportional to the mass of
the person [6]. The heavier the person, the lower oscillation frequency will be produced.
A low frequency of oscillations will produce longer period of time. Thus, it will have a
greater generated output energy.
Puzzle Floor Mats are connected mats in which the circuit of each mat are
connected in series. Cascading of operational amplifiers is done through connecting each
op – amps in series, thus, increasing the total gain. The gain is directly proportional to
the voltage output [7]. Batteries that are cascaded in series produce a higher voltage
output. The Puzzle Floor Mats are cascaded like cascading op – amps or batteries in
which it increases the voltage output of the whole Puzzle Floor Mat.
With the aid of the facts, the proponents therefore offer to design an Energy-
Harvesting Piezoelectric Puzzle Floor Mat using Piezoelectric Crystals. Instead of floor
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tiles, which are usually made by clay or ceramics, a Puzzle Floor Mat will be used to
generate electrical energy through footsteps. These mats are made of rubber sheets which
are soft and elastic that will produce greater and longer vibrations. Greater and longer
vibrations will produce more energy to be converted.
The added parameters of the proponents’ study are the output energy of the
Piezoelectric Puzzle Floor Mat, installation and cost, weight of the project, as well as the
operability and maintenance. The output energy is the most significant parameter because
it will help in determining which devices it can supply. Installation of these floor mats
are very easy and low cost because it does not need to be installed like floor tiles. It can
just be laid down on the floor and materials that will be used are cheaper and available
in the Philippines. In addition, the frequency of oscillations of the spring has an influence
on the vibrations produced by the project. The weight of the person stepping on the mat
affects the frequency of oscillations which means it is also an important parameter to be
determined. Lastly, the operability and maintenance of the project is very simple since it
can be moved in different places and easy to fix when something is wrong.
1.2 Statement of the Problem
Sources of energy in the Philippines have been diminishing because of a big
demand due to the increasing population in the country. The increasing demand in energy
impels researchers to find a renewable alternative sources. Piezoelectricity is a
technology in harnessing energy used in foreign countries as an alternative source.
Various energy harvesting piezoelectric devices have been developed like Piezoelectric
Floor Tiles.
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The current study will design and localize existing Energy Harvesting
Piezoelectric Puzzle Floor mats. Puzzle Floor Mats will have a soft surface because it is
made of rubber sheets, hence making a longer and larger vibration due to the springs. It
will also be cascaded for a larger energy output. This study will contribute regarding the
problem of declining energy source of the country by using Piezoelectric Puzzle Floor
Mat which harness energy through oscillation.
1.3 General Objective:
To design and simulate the harnessing of energy of a Piezoelectric Puzzle Floor
Mat using Piezoelectric Crystals
1.4 Specific Objective:
To design a rubber Puzzle Floor Mat using Piezoelectric Crystal in converting
mechanical energy to electrical energy
To design a circuit for harnessing, monitoring and storing of the electrical energy
converted
To design a Piezoelectric floor mat which produce larger and longer vibrations
To attain an appropriate energy output of 2.5 Joules per step or higher of the
Puzzle Floor Mat through continuous testing
1.5 Scope and Delimitation
This study will also focus on harvesting energy of the Puzzle Floor Mat that has
a dimension of 20” by 20” by 3”. Each floor mat will have at least 25 piezoelectric
crystals, 25 springs, and another 4 big springs in the inner part of the mat which is beside
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the piezoelectric crystals that will contribute in producing more vibrations. Furthermore,
this study will use a lithium – ion battery with 3.7 volts voltage output.
The generated energy may depend on the weight of the person stepping on the
mat. A maximum of two persons can step on one mat. This study will only be
implemented indoors where many people are passing like building entrance or lobbies.
It can also be moved to different places. This study will monitor the output energy per
step manually using an energy or V/I meter. This study will use plugs that will help in
cascading the floor mats. The exposed jacks and plugs will have specific coverings for
protection against any liquid. However, the floor mat itself should not be soaked too
much with water because materials are not water proof.
The floor mat should be cleaned every day. The most common issue about the
maintenance of rubber floor mats is dirt and small debris which comes from the shoes
and slippers. In cleaning the floor mats, a vacuum or manual gentle scrubbing can be
applied. According to the data we gathered from the clinic, the average weight of the
students that are enrolled in FEU-Institute of Technology is 63kg. The maximum weight
that the floor mat can withstand is 36,993 kg. Therefore, any person can step on the floor
mat.
During testing, the researchers will use a controlled environment. Only one
person, weighing exactly 63 kg, will step on the mat. The person should step on the mat
in his natural way of walking. Moreover, using a controlled environment, the researchers
will be able to determine whether the energy is constant at every trial.
This will not include the study of any kind of tiles. The proponents will use a mat
that is made of rubber sheet which is water resistant in order to avoid any damage in the
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internal parts of the mat in case that it will be wet. In addition, the Puzzle Floor Mat will
not generate energy if the foot is still on the mat unless the foot is removed.
1.6 Significance of Study
The electric energy consumption during 2010 was 64.52 billion kilowatt-hours in
the Philippines, which accelerated from 48.96 billion kilowatt-hours in the year 2013.
The electrical energy consumed in 2014 was 56.84 billion kilowatt-hours which was
ranked as 41st worldwide [9].This study will recommend a way to help lower the
electrical energy consumed annually by utilizing energy that is being dissipated by
human beings regularly. When a person is walking, an energy is formed through footsteps
or vibrations and can be converted into electrical energy. The harvested energy from
human footsteps is large enough to operate an electrical appliance/s and other equipment
which is costless. This project can also be placed in sidewalks to energy the stoplights
and the streetlamp since more footsteps from people walking through the Puzzle Floor
Mat will generate more energy. This study may help energy the lights in the hallways of
the schools and other business companies from the employees or students that are
walking through the Puzzle Floor Mat. Materials that would be used in this study are
locally available which is an advantage since importation of the materials will no longer
be needed.
The future researchers can enhance and develop the features and specifications of
the project as a recommendation. The Piezoelectric Puzzle Floor Mat can be converted
into a water proof floor mat. Floods caused by typhoons are not new in the Philippines.
If it is converted into water proof floor mats, it can be placed in the sidewalks where
pedestrians can walk through it and can still accumulate vibrations regardless of the
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heavy rain and the flood. Moreover, since raindrops can create vibrations when it falls to
the mat, it can still generate energy during rainy days.
Definition of Terms
Piezoelectricity. The concept used in the project wherein it has the ability of a
material to produce an AC voltage from a mechanical energy in a form of vibrations or
stress specifically human footsteps. It also called as piezoelectric effect.
Piezoelectric transducer. It involves a crystal between two plates which form
vibrations and converts the vibrations to weak AC voltage.
Energy harvesting. A method of collecting small amount of energy which is in a form
of heat, light, sound, vibrations or movement. In this study, energy can be harvested
through vibrations and movement and will be used to convert into an electrical energy
using Piezoelectric Puzzle Floor Mat.
Water resistant. The ability to resist the penetration of water in some certain depth
but not entirely and one key feature of the Piezoelectric Floor Mat.
Oscillations. Produced by the vibrations.
Cascade. Connecting the circuit of each Piezoelectric Puzzle Floor Mats in series.
Op – amps. Stands for Operational Amplifiers.
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Chapter II
Review of Related Literature
This chapter discusses the review of related literature about Energy
Harvesting Piezoelectric Puzzle Floor Mats. It explains relevant concepts and materials
involving with the current study to provide the foundation of the proposed study.
2.1 Review of Related Materials
2.1.1 Floor Mats
Floor Mats are standard equipment commonly used in vehicles which
have carpet covering floor. Floor mats are usually flat and typically consist of a
thin layer of lightweight carpeting bonded to a thin layer of polymer type material
that blocks water from getting through [10].
Pros:
Softness and Elasticity of the Floor Mat
Floor Mats are soft and elastic and when a foot steps on it,
it cause vibrations. These vibrations last longer in soft
materials which cause to produce more mechanical energy
that will be converted to electrical energy.
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2.1.2 Rubber Sheets
Rubber sheets are essentially polymers of isoprene. These rubber sheets
are elastic materials that is achieved by thickening and drying the latex from
certain plants which is the milky juice of any of various tropical plants like genera
Hevea and Ficus. Later prepared as sheets [11].
Pros:
Durability
Rubber sheets are strong and resilient against a variety of
conditions. If it installed properly, it can last for a long
time.
Soft
Given the fact that the material is strong and can last for a
long time, rubbers are actually soft.
Water resistant
Rubber materials are not absorbent of water or liquid
which there’s no concerns about damage from simple
liquid spills.
Cons:
Slippage
If rubbers are not textured, it can become slippery when
liquid is spilled on it.
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Dull finish
The appearance of the rubber sheets are unattractive to
many people which is why it is not a common option for
floorings where many people can see it.
Difficulty in Cleaning
Rubbers picks up grease so easy and have a tendency to
discolor when detergents are used for cleaning.
2.1.3 Piezoelectric Transducer
Piezoelectric transducer is a device that converts one type of energy to
another by using the piezoelectric properties of certain crystals or other materials
[12]. It generates an electrical potential or voltage when a force or pressure is
applied onto the piezoelectric device or material. Piezoelectric transducers are
epitome of a good converter of mechanical energy to electrical.
2.1.4 Piezoelectric Crystals
Piezoelectric Crystals is a small scale energy sources. When these crystals
are squeezed, a vibration occurs that produces a very small voltage. These crystals
bend in different directions at different frequencies in which this bending is called
the vibration mode [13].
2.1.5 Lithium-ion Battery
Lithium-ion is a rechargeable battery and is composed of one or more cell.
A cell has a positive electrode that is connected to a battery’s positive terminal.
A cell also has a negative electrode that is connected to the negative terminal.
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Electrolyte is a chemical that is between the negative terminal and positive
terminal of the cell. A battery is said to be a lithium-ion if the movement of ions
is one way when charging and when it moves the opposite way while the battery
is discharging. [14]
Pros:
Light weight
- Lithium-ion batteries have the same weight with the other
rechargeable batteries but lithium-ion batteries are light
weight.
High energy density
- Lithium-ion batteries can store lots of energy in it because
of very high energy density and the battery is made of
light weight lithium and carbon. The lithium in the battery
is also a highly reactive element.
Convenient
- A lithium-ion battery that weighs 1 kilogram can store the
same amount of energy which a 6 kilograms lead-acid
battery can store.
Charging and discharging cycle
- Lithium-ion batteries can handle many charging and
discharging cycles
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Cons:
Short life span
- Lithium-ion batteries that either used or unused have a
short life span of 2 to 3 years from the date of manufacture.
Temperature exposure
- Lithium-ion batteries are very sensitive to high
temperature hence they tend to degrade much faster when
exposed to heat.
Figure 1. Charging and discharging phenomena in Lithium Ion batteries
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This figure shows a lithium-ion batteries while charging and
discharging. A lithium-ion battery is charging when a chemical compound
in the positive electrode gives up a few of the lithium ions, where it travels
to the chemical compound in the negative electrode and remain there. The
battery will store energy to absorb energy. The battery is discharging
when the lithium-ions from the negative electrode will move back across
the electrolyte to the positive electrode to produce energy from the battery
since the electrons flow around the circuit on the opposite way to the ions.
Lithium is deposited on the positive electrode if the ions and electrons will
combine in the positive electrode [14].
2.1.6 Full-Wave Rectifier
There are 4 diodes in the full-wave rectifier circuit. All the diodes are
connected with each other and are forward-biased. Each diode conducts for 180º
of the input cycle. The frequency of the output in a full-wave rectifier is twice the
input frequency [15].
2.1.6.1 Bridge Full Wave Rectifier
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Figure 2. Bridge Full-Wave Rectifier
This figure shows an image of Bridge Full-Wave Rectifier Circuit.
The first diode (D1) and the second diode (D2) are said to conduct current
during the positive half-cycle of the input in the bridge-full wave rectifier
operation. A voltage is developed across the load resistor (RL) that
resembles the positive half of the input cycle. Meanwhile, the remaining
diodes D3 and D4 are reverse-biased. During the negative half-cycle of
the input in the bridge-full wave rectifier operation, the third diode (D3)
and fourth diode (D4) conduct current in the same direction through the
load resistor (RL) as during the positive half-cycle. Meanwhile, the other
diodes which are D1 and D2 are reverse-biased. A full-wave rectified
output voltage appears across the load resistor (RL) as an outcome [15].
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2.1.7 Step – up Chopper
The supply of the step-up chopper is a rectified AC or a battery. The
purpose of a chopper is to improve the DC voltage by converting the fixed DC
voltage into a variable DC voltage. A chopper is a high speed switch that connects
and disconnects the load from the source to attain a variable DV output voltage.
Chopper is also known as DC transformer. A step-up chopper is also known as
boost converter which is used to step-up the voltage from its input side [16].
2.1.8 Compression Springs
Compression springs is an open coil – helical spring which is usually
coiled as a constant – diameter cylinder. When compression force from a load is
applied to the spring, the spring then becomes squeezed. However, with the
design of wires, it tries to go back to its original shape thus pushing the load back
[17].
2.2 Working Theories
2.2.1 Energy Harvesting
Energy Harvesting is the process of acquiring amounts of energy from
one or more natural sources of energy and storing them for future use. Energy
Harvesting plays a vital role in distributing energy to certain applications. It uses
devices which enables to acquire, store, convert and manage efficiently and
effectively the generated energy and supply it in a form that can be used to
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perform a helpful task [18]. Moreover, Energy Harvesting, from natural sources
where an application can be implemented and sources of natural energy is
limitless, is an alternative source of energy to wall plugs and batteries which are
inconvenient and costly. Energy Harvesting includes photovoltaics,
thermovoltaics, piezoelectrics, electrodynamics and many more. Energy
harvesting has its advantages and disadvantages which are enumerated below
[19].
Pros:
Renewable and Abundance
Harvested energy can be manufactured quickly, and
require no other source of energy to operate. One good
example is wind. Wind is a limitless, naturally occurring
phenomenon that is present over the world, and represents
a clean and renewable domestic energy resource.
Cost – effectiveness and continuing improvement of performance
Natural sources of energy costs less since it can be
generated through air, water, vibrations, sun and etc.
Moreover, the performance of the energy harvesting
system can be enhance.
Can be combined into smart integrated energy system
The harvested energy can easily be incorporated with
smart energy systems. Also, different technologies can be
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combined like monitoring systems using Bluetooth,
Zigbee and other technologies.
Cons:
Variable amount of energy generated
There is inconsistency with the amount of energy
generated with natural sources of energy. For an example,
energy generated through footsteps, the number of people
that will step in the energy harvesting devices will never
be constant making the generated energy varying.
2.2.2 Piezoelectricity
Piezoelectricity, also called the piezoelectric effect, is the produce of
electric potential or voltage from the crystals when mechanical stress is applied
through squeezing and deforming the crystal [20]. Piezoelectric effect has a
unique characteristics wherein it is reversible. It can function as a direct
piezoelectric effect where stress is applied to generate electricity. It can also
function as a converse piezoelectric effect where electric field is applied to
generate stress [21].
2.2.2.1 How Piezoelectric Effect Works
The charges in a piezoelectric crystal are normally balanced even
if it is not symmetrically arranged. Before exposing the material to
pressure and stress, the centres of the positive and negative charges of
each molecule concur wherein the charges are reciprocally cancelled.
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Consequently, electrically neutral molecule appears. The piezoelectric
effect happens when the balanced and neutral charge is disturbed through
squeezing the crystals which causes the separation of the positive and
negative charges of the molecules where little dipoles are created.
Subsequently, the facing dipoles inside the material are both cancelled.
The material becomes polarized because of the distributed linked charges.
When the crystal lattice is distorted, the imbalance of the charge creates a
potential difference. This potential difference is also known as the voltage
[22].
2.2.3 Frequency of Oscillation
The oscillation frequency expands as the stiffness of the spring increases.
The frequency of oscillation also expands if the reduction on the mass attached
to the spring is applied [24]. The frequency of oscillation is measure in cycles per
second is mathematically expressed as:
𝑓 = 1
2𝜋√
𝑘
𝑀 Equation 2.2.4
Where: k = spring constant (𝑘𝑔
𝑠2)
M = mass (kg)
2.2.4 Cascaded Operational Amplifier Circuit
The cascaded operational amplifier circuits produce higher voltage gain.
An operational amplifier is in cascade connection if the output of an operational
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amplifier circuit is the input of the next operational amplifier circuit. The total
output gain of the cascaded operational amplifier is the product of the individual
operational amplifier circuits [25]. If there are 3 operational amplifier circuits
given, the overall gain in cascade connection will be mathematically expressed
as:
𝐴 = 𝐴1 𝑥 𝐴2 𝑥 𝐴3 Equation 2.2.5
Where: A1 = stage 1 or 1st gain in the operational amplifier circuit
A2 = stage 2 or 2nd gain in the operational amplifier circuit
A3 = stage 3 or 3rd gain in the operational amplifier circuit
The gain is directly proportional to the voltage output of the operational
amplifier circuit, hence when the gain increases the voltage output also increases.
2.3 Review of Related Works and Studies
2.3.1 Foreign Works and Studies
2.3.1.1 Japan Harnesses Energy from Footsteps
In Japan, special flooring tiles made of rubber sheeting and
stoneware tiles are installed in their ticket turnstiles. These flooring tiles
generates energy from footsteps. The idea behind this is piezoelectricity.
Every steps of the passenger generates a vibration that acts as an energy.
The purpose of rubber sheeting is to absorb the vibrations of the steps
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made by the people who uses the station. This energy will be multiplied
by the number of people who crosses the station. Like in Tokyo station,
the energy will be multiplied over the 400,000 people who crosses the
station in an average day and this energies are sufficient to light up the
electronic signboards, according to East Japan Railway. Takuya Ikeba, a
spokesperson in JR East, said that “We are just testing the system at the
moment to examine its full potential". Same concept is applied in Shibuya
station wherein on an average week, 2.4 million people passes through
this station. Soundenergy Corp. applied the “Energy Generation Floor”.
Yoshiaki Takuya, a planner with Soundenergy Corp. said that "An
average person, weighing 60 kg, will generate only 0.1 watt in the single
second required to take two steps across the tile. But when they are
covering a large area of floor space and thousands of people are stepping
or jumping on them, then we can generate significant amounts of energy."
The generated energies can be stored in a capacitor and can be distributed
to the part of the station including the electrical lighting system and the
ticket gates. It is important to know the generated output energy so that it
can easily determine what type of low energy device it can only energy
up [26].
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Figure 3. Commuters at the Tokyo station walk on a piezoelectric
sheet which generates electricity when pedestrians step on it
This figure shows the application of piezoelectric floor tiles in
Tokyo, Japan. It is used to energy up electrical lighting system and the
ticket gates in train stations. These floor tiles uses a capacitor as a storage.
2.3.1.2 A Shoe-Embedded Piezoelectric Energy Harvester for Wearable
Sensors
An interesting approach for acquiring a clean and sustainable
electrical energy to energy wearable sensors, that are used for health
monitoring, activity recognition, gait analysis and so on, is harvesting
mechanical energy from human locomotion. This study focused on a
piezoelectric energy harvester for the parasitic mechanical energy in shoes
which came from human locomotion. A sandwich structure is designed
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for the harvester to fit and be compatible with the shoes as well as a
consideration for both high performance and excellent durability. An
average output energy of 1mW during a walk at a frequency of roughly
1Hz is obtained from the harvester. Through integrating the harvester with
a energy management circuit, a direct current (DC) energy supply is
created. The DC energy supply is verified by driving a simulated wireless
transmitter that can be activated once every 2 – 3 steps with an active
period lasting 5ms and a mean energy of 50 mW. Hence, this study
illustrates the feasibility of using piezoelectric energy harvesters in
energying wearable sensors. Wearable sensors are becoming smaller and
are frequently used by many which indicates that a need for portable
source of electrical energy is important [27].
Figure 4. A Shoe-Embedded Piezoelectric Energy
Harvester for Wearable Sensors
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This figure shows the design of the shoe embedded piezoelectric
energy harvester for wearable sensors. Inside the shoes is the harvester
which contains the energy management circuit and the DC energy supply.
The harvester is mounted inside the shoes with a wearable sensors to
generate electrical energy.
2.3.1.3 Source of Vibration for Crystal Previous Work [28]
2.3.1.3.1 Power Generating Sidewalk
The series connection of piezoelectric crystals are located
under the walking section of the pedestrians on sidewalks and
pavements. Batteries like lithium and capacitors will be charged
by receiving the generated voltage from the piezoelectric crystals
in series. The limitation in the usage of the batteries will depend
on the received generated voltage from the crystals arranged in
series connection.
2.3.1.3.2 Power Generating Boots or Shoes
A groundbreaking design for operating battlefield
equipment where a mechanical energy will be converted into an
electrical energy was proposed by the United States Defense
Advance Research Project Agency (DARPA). The piezoelectric
generators will be inserted in the soldier’s boots. The generated
energy will help to operate or energy up the battlefield equipment.
Although the use of the design is based on good purpose, there is
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still an effect in the body of the soldier wearing the energy
generated boots or shoes. As a result, the innovation was
discontinued considering the person wearing the boots
experienced uneasiness or discomfort for exerting additional
energy to generate more energy.
2.3.1.3.3 Gyms and Workplaces
Many gym enthusiasts always help to create vibrations
from the machines and equipment unknowingly. Since there are
effortless number of vibrations that can be accumulated, the
research workers conceptualized an idea to generate energy in an
easy way. At workplaces, there are numerous ways to generate
energy even if the employee is just sitting on a bench or chair. The
energy generated from an employee who is sitting can be
accumulated in a battery for later use by placing the piezoelectric
crystals in the chair. Furthermore, the research for the vibrations
gathered in several parts of a vehicle like foot rests, car seats, and
clutches are being accomplished to make effective use of it.
2.3.1.3.4 Mobile Keypad and Keyboards
Charging in a laptop is an efficient way when there is a
limited electrical outlet but charging with the use of mobile
keypad and keyboards will be more favorable. The piezoelectric
crystals can be placed under the keys of a mobile keypad and
26
keyboard which will cause vibration with the intention of charging
an electronic device.
2.3.1.3.5 Floor Mats, Tiles and Carpets
Placing a floor mats, tiles and carpets in public places can
collect enormous vibration for the reason that more people are
walking through the piezoelectric materials. A set of piezoelectric
crystals will be placed in the flooring design like floor mats, tiles
and carpets which are regularly placed in public places.
2.3.1.3.6 People Powered Dance Clubs
In western places like Europe, piezoelectric crystals can be
used to energy up the equipment in several nightclubs since the
crystals will be placed beneath the dance floor. Great supply of
voltage will generate from the dance floor from people walking or
dancing through it.
2.3.1.4 Piezoelectric Energy Harvesting
Piezoelectric energy harvesting floor have been implemented at
Rutgers University in Busch Campus Center. The project was installed in
the main highway where a high volume of people’s steps were gathered.
The main goal of the project was to increase the awareness on how to
gather energy from footsteps. The energy generated can supply the
television displays that track the energy harvested. The energy harvested
is about 7 kWh per day using about 20,000 people walking through the
27
floor tile throughout the day. The proposal of the project gave an option
which are renting the floor tiles and continuing on the expansion to the
other publicly areas on the New Brunswick campus. The estimated cost
of the project are $50,000 for renting the floor tiles and $800,000 for the
full permanent installation. The floor tiles can be installed in top of the
current floor and with the use of an inverter, the generated energy can be
connected to the electrical system of the building and can supply any
electronics like television display. The force exerted on the floor by a
person is approximately about 1 to 1.3x of the body weight. The project
can harvest 50% of the energy. The area covered by the floor tiles is
approximately 4,000 𝑓𝑡2for using 1400 tiles. The total implementation
cost including the installation and maintenance cost is about $800,000. A
50-tile system can be rented because of high installation which are about
$65,000 including the installation and maintenance and it can be renter
over 1-3 year period. A 50-tile system can cover about 18 feet by 6 feet
rectangular area. With the use of this, it can generate 173 Watts which can
supply the monitoring and displaying of the harvested energy [29]. The
monitoring is 5-days in a week and 15 week per semester based on the
table below.
28
Figure 5. Energy Harvested of Phase 1 and Phase II
This figure shows the table about energy harvested of Phase 1 and
Phase 2 daily, weekly and per semester. The phase I is the rental of the
tiles and the phase II is the installation of the tiles. The phase I consists of
50 piezoelectric floor tiles while the phase II consists of 1400
piezoelectric floor tiles. As shown in the results, the difference in the
generated output energy of phase II to phase I in the semester calculation
is 504.5 kWh.
2.3.2 Local Works and Studies
2.3.2.1 In-Wheel Piezoelectric Generator for Lighting Applications of
Mining Trolleys
Technology has been improving and gradually changing as years
go by. Technology needs electricity for charging purposes and to energy
up an equipment or a device. Piezoelectric transducer is one of the many
ways on how to produce an alternative energy. A piezoelectric transducer
uses a piezoelectric material like crystal. The concept in a piezoelectric
crystal is to convert the mechanical energy caused by the pressure into an
29
electrical energy. Piezoelectric crystals are applicable especially in
pressure that are heavy in weight. The weight coming from the wheels of
the mining trolley is an ideal example for heavy weight pressure. A
piezoelectric transducer is inserted to the wheels of the mining trolley to
harvest energy since it always carry a very large amount of mining loads.
The generated energy can be used as the energy source to light the mining
trolley. The energy consumption will be reduced from energy line
companies by using an enough alternative source from the piezoelectric
transducer [30].
2.3.2.2 Energy-Harnessing Footwear Using Combined Electromechanical
and Piezoelectric Transducers for Charging Supercapacitors (2009)
Energy harnessing footwear have been popular activating low
energy devices using piezoelectric transducer. These devices acquire
energy from the footsteps of the person using the shoes. This study aims
to provide a new and improved energy harnessing footwear that uses not
only piezoelectric transducers but a combine piezoelectric and
electromechanical transducer which are both integrated in the shoes. The
harvested energy will be stored and will be used to operate low energy
devices such as Light Emitting Diodes and even Cellular Phone. In storing
the harvested energy, an environment friendly component will be used as
the energy storage. This component is a supercapacitor [31].
30
Figure 6. Energy Harvesting Shoe
This figure shows the design of the Energy – Harnessing
Footwear. The project used two transducers which are the piezoelectric
and electromechanical transducers. These transducers are located in the
shoe sole.
2.3.2.3 Power Generation for Remote Areas Utilizing Piezoelectric
Transducers Harnessing Wind and Wave Energy (2011)
Piezoelectric transducers are widely used as energy harvesting
material. This study aims to provide simple lighting in remote areas using
piezoelectric transducers as energy harvester. Wind and wave are two of
the most popular sources of ambient energy. These energy are harvested
using a prototype. This prototype are specifically develop to harvest and
store the energy acquired and perform energy regulation techniques with
the use of super capacitors and then transfer the energy to a rechargeable
battery [32].
31
Chapter III
Research Methodology
This chapter discusses the methodology used in the study. It explains each section
of the design considerations and hardware specifications of the prototype. The population
and samples are also explained in this chapter. Furthermore, this chapter shows the ideal
set-up of the Piezoelectric Puzzle Floor Mat. Succeeding section explains the conducted
procedure and analysis to examine the appropriate output energy. This study also
illustrates particular diagrams to expound how the output energy will be attained which
is the main objective of this project.
3.1 Conceptual Framework
Figure 7. Conceptual Framework
This figure shows the conceptual framework of the system. The input in the
project is the footsteps. Footsteps are form of mechanical energy. Vibrations are the
wasted energy that comes from the human footsteps. An average person can take 3,000-
5,000 steps a day [2]. These footsteps came from only one person, it means that if there
OUTPUT PROCESS INPUT
Footsteps
Vibration
Converts the
vibrations to DC
voltage
Usable DC
voltage
32
are many people walking, there are also a higher calculation of the footsteps that can be
collected per day. The project must be placed in a public place to acquire many footsteps.
The generated output energy will be higher if there are many footsteps walking through
the project. The main process of the project is to convert the vibrations produced by the
footsteps into DC voltage. The output in this project is in the form of usable DC voltage
which can be the supply voltage for some low energy applications.
3.2 Block Diagram
Figure 8. Block Diagram
Mat Surface
Piezoelectric circuit
Full-Wave Rectifier
Step-Up Chopper
Lithium-ion Battery
Wired monitoring
using Energy meter
or V/I meter
Load
Footsteps
33
This figure shows the block diagram of the system. The human footsteps will
make contact and apply pressure to the mat surface that will produce vibrations. The
piezoelectric circuit converts the vibrations caused by the footstep into an AC voltage.
The output AC voltage is converted to DC voltage using a full-wave bridge rectifier. The
fixed DC output voltage of the rectifier will be converted into a variable DC voltage with
the use of a step-up chopper and will be stored in a Lithium-ion battery. The generated
voltage can be applied to a load but depending on the kind of load it can only supply. The
output energy per step of the project is monitored by using an energy or V/I meter.
3.3 Schematic Diagram
Figure 9. Circuit Diagram of the System
Where:
X1 = 25 piezoelectric crystals connected in series
D1, D2, D3, D4 = 1N4001
C1 = Electrolytic capacitors, 470µF 25V
B1 = Lithium-ion battery, 3.7 VDC
34
This figure shows the circuit diagram of the project. This also shows the
interconnection of the Full-Wave Bridge Rectifier, Step-Up Chopper, Lithium-ion
Battery, and the Full-Wave Bridge Inverter. The voltage source of the circuit is AC
voltage produced by the 25 Piezoelectric Crystals connected in series. The generated
energy will be consumed by the load if there is a load.
3.3.1 Full-Wave Bridge Rectifier
Figure 10. Full-Wave Bridge Rectifier
This figure shows the Full-Wave Bridge Rectifier circuit diagram. The
Full-Wave bridge rectifier converts the AC voltage source that produces by the
25 Piezoelectric Crystals connected in series into a pulsating DC. The capacitor
acts as a smoothing capacitor that smooth out the pulsating DC produced by the
Full-Wave Bridge Rectifier and creates ripples.
35
3.3.2 Step-Up Chopper (DC/DC converter)
A Chopper is a kind of a DC/DC converter and its energy source could be
a rectified A.C. or a battery. The main function of a Chopper is to convert a fixed
DC source into a variable DC voltage. In the project, the input voltage of step-up
chopper is the rectified output voltage of the Full-Wave Bridge Rectifier.
3.3.3 Lithium-ion Battery
Figure 11. Lithium-ion Battery
This figure shows the Lithium-ion Battery which purpose is storing of the
DC voltage output from the step-up chopper.
36
Table 1. Specifications of Lithium-ion Battery
This table shows the specifications of Lithium-ion Battery. The output voltage of
Lithium-ion battery is 3.7VDC
3.4 PCB Layout
Figure 12. PCB Layout
This figure shows the PCB layout of the circuit diagram of the system and the
connection of each components in the PCB.
Model GEB5650122
Voltage Output 3.7V DC
Current Capacity 4000mAh
Charging Voltage 4.25V 500mAh
37
3.5 Flow Chart of Process
Start
Wait for the person
to finish stepping
on the floor mat
Footsteps
Is the person
finish
stepping on
the floor
mat?
Vibrations produced will be
converted to AC voltage with
the use of piezoelectric circuit
AC will be converted to DC
using a full-wave bridge rectifier
Fixed DC voltage to variable DC
voltage using a Step-up Chopper
A
38
Figure 13. System Flowchart
This figure shows the system flowchart of the system. The system will start when
the footsteps have made contact to the surface of the floor mat. The system will ask if the
person that made contact to the floor mats’ surface is finished stepping on the floor mat.
The system will wait for the person to finish stepping in the floor mat if the answer is
No, it will return to the question. The system will create a loop until the question is
satisfied. The vibrations produced will be converted to AC voltage with the use of
piezoelectric circuit if the answer is YES. The AC output voltage from the piezoelectric
A
DC output stored in a Lithium-ion battery
DC voltage
Monitor using energy or
V/I meter
Is there
a load?
The load will consume the DC
electrical energy stored in the
Lithium-ion battery
End
39
circuit will be converted into a DC voltage with the use of a full-wave bridge rectifier.
The fixed DC voltage output of the rectifier will be converted to variable DC voltage
with the use of a step-up Chopper and will be stored to a Lithium-ion battery for later
use. The system will ask if there is a load connected to the circuit. The load will consume
the output DC electrical energy if there is a load connected to the circuit. The energy or
V/I meter are the device that will be used to monitor the energy of the mat per step. The
system will standby if the floor mat stops to oscillate.
3.6 Test Population
Through the data gathered from Computer Services Office (CSO), the average
number of students that enter the building of FEU – Institute of Technology per day is
5,780 from November 9 to 14, 2015. The average number of students that leaves the
school premises is the same as the average number of students that enter. The researchers
use the exit as the location of the device so most of the students will be able to step on
the mat and to avoid getting wet of the Piezoelectric Puzzle Floor Mat. Due to the
inconsistency of implementing of tapping the I.D., the researchers chose the date of
November 9-14 of 2015 because of the strict implementation of tapping the I.D. in the
entrance.
3.7 Treatment of Data
3.7.1 Calculations for the number of trials
The researchers set a standard error tolerance level of 5%. The researchers
the error tolerance of 5% because it is the department standard and usually used
40
in thesis. The researchers will determine the number of samples/trials needed for
the project using the Slovin’s formula:
𝑛 = 𝑁
1+𝑁𝑒2 Equation 3.7.1
Where: n = number of samples/trials
N = total population
e = error tolerance
Computing for the number of samples using Slovin’s formula, N = 5,780
n = 5,780
1+(5,780)(0.05)2 = 374.11 ≈ 374 trials
Thus, the number of trials needed to attain the appropriate energy output
of the Piezoelectric Puzzle Floor Mat through continuous testing is 374.
3.7.2 Calculation for the Tolerance
Tolerance = Average energy output − Energy output
Average energy output x 100%
41
3.8 Testing Procedure
1. Assemble and place the Piezoelectric Puzzle Floor Mats on the floor
2. Be sure that the battery is fully discharge at every first trial
3. Have only one person weighing exactly 63kg to perform the testing in
order to know whether the mat acquires a constant value of energy for
every trial and to have a constant force applied to the mat. The person
must step on the mat in his natural/normal way of walking
4. Measure the energy per step acquired by the system using an energy
or V/I meter for 374 people a day for 16 days in order to test also if
the floor mat can still be functional when it is use every day and to
assume that the number of average students that enter to the school
premises stepped on the floor mat
days = ave. students
number of trials=
5,780
374= 15.45 ≈ 16 days
3.9 Proposed Table for Test Results
Table 2. Table for test results
Day Number
Trials Energy Output per step
(J/step)
Tolerance %
1
2
42
3
4
5
.
.
.
374
Ave. Ave.
Average energy output for 16 days: ______________
Average percentage tolerance for 16 days: ________________
The table above shows the number of trials, the energy output in each trial, the
percentage tolerance, if the battery is fully charged, the average energy output and the
average percentage tolerance. The researchers will perform the testing for 16 days,
therefore it will have 16 tables for each day
43
3.10 Proposed Project
3.10.1 Ideal Set up
Figure 14. Ideal Set-up: A man stepping on the floor mat
This figure shows the ideal set up of the device where a man steps onto
the mat. Thus, creating vibrations that will produce mechanical energy which is
then converted to electrical energy.
3.10.2. Design Considerations of Puzzle Floor Mat
Figure 15. Dimensions of the Puzzle Floor Mat
44
This figure shows the dimensions of the Piezoelectric Energy Harvesting floor
mat which is a 20” by 20” by 3”. The dimension of the mat was in a square shape so that
the force exerted on the Puzzle Floor mat is equally distributed.
Figure 16. Top View of the Puzzle Floor Mat
This figure shows the top view of the Puzzle Floor Mat which consist of male
jack whose purpose is to connect the output energy of the mat to the input of the other
mat and female jack whose purpose is to receive the output of the other mat and connect
it to the input of the mat.
45
Figure 17. Inner Part of the Puzzle Floor Mat
This figure shows the inner part of the Puzzle Floor Mat where it consists of
Piezoelectric Crystals, wires, and springs. The Piezoelectric Crystals are connected in
series to have a higher electrical energy. The length of the springs is 1”. The maximum
weight it can handle is 36,993kg. Therefore, the capacity of the floor mat can still sustain
the weight of any student as long as it does not exceed 36,993kg.
To compute for the maximum weight capacity of the mat, the researchers used
the formula of stress. Stress is ratio of the force to the cross-sectional area and tends to
compress or shorten the material [33]. The yield strength/stress for steel is 250Mpa and
the area of the project’ supports is 1.5” by 1.5”.
46
ℴ = Force
Area
250MPa = (max 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 kg)(9.81
ms2)
(1.5inches)2 (2.54𝑐𝑚1𝑖𝑛𝑐ℎ
)2
(1𝑚
100𝑐𝑚)2
Max weight in kg = 36,993.11927 kg ≈ 36,993kg
Table 3. Specifications of Smaller Spring
This table shows the specifications of the smaller springs. The spring’s model,
outside diameter, free-length, approx. load and solid height, solid height, maximun
deflection, and the spring rate/constant are shown in the table. The springs should be
sturdy enough so that when a person step on the mat, it will not be deformed.
Lee Stock number (model) LHP 098G 04S
Outside diameter 0.48” or 12.19mm
Free Length 1” or 25.40mm
Approx. Load at Solid Height 122.18 lbs or 55.421 kg
Solid Height 0.715” or 18.16mm
Max. deflection 0.285” or 7.24mm x (0.80)
Spring rate/constant 429.96 lb/in or 7.678 kg/mm
47
Table 4. Specifications of the Bigger Springs as a support
Lee Stock number (model) LHP 130J 03S
Outside diameter 0.72” or 18.29mm
Free Length 1” or 25.40mm
Approx. Load at Solid Height 165.10 lbs or 74.889 kg
Solid Height 0.705” or9mm
Max. deflection 0.295” or 7.51 mm x (0.82)
Spring rate/constant 559.80 lb/in or 9.997 kg/mm
This table shows the specifications of the bigger springs as a support. The spring’s
model, oustdie diameter, free-length, approx. load and solid height, solid height,
maximun deflection, and the spring rate/constant are shown in the table. The springs
should be sturdy enough so that when a person step on the mat, it will not be deformed.
48
(a.)
(b.)
Figure 18. Comparison of design with respect to vibrations
This figure shows the comparison of design of existing study with the researchers’
study with respect to vibrations. Figure a shows the design of an existing study of
Piezoelectric floor tile which has four springs as a support to the floor tile. While figure
b shows the design of current study which has a total of 29 springs as a support to the
floor mat. Figure b can produce larger and longer vibrations since it has the more number
of springs. Moreover, the location of the spring of figure b is just below the floor mat
unlike figure a. Thus, the effect of the steps is directly to the springs. The more number
of springs, the less its tendency of going sideways.
49
References
[1] I. Gonzales, "Power Crisis Looms in 2015," The Philippine Star, 22 July 2014.
[2] M. S. N. N. G. Monika jain, ""VIDYUT Generation via walking: Analysis"," International
Journal of Engineering Sciences and Research Technology, Feb 2013.
[3] A. K. Itika Tandon, "A Unique Step Towards Generation of Electricity via New Technology,"
International Journal of Advanced Research in Computer and Communications Engineering,
vol. 3, no. 10, 2014.
[4] C. Gaylord, "The Christian Science Monitor," 26 September 2007. [Online]. Available:
http://www.csmonitor.com/Technology/Pioneers/2007/0926/power-harnessed-one-
step-at-a-time.
[5] "Wikipedia," MediaWiki, 2 June 2015. [Online]. Available:
https://en.wikipedia.org/wiki/Impact_(mechanics).
[6] "SparkNotes," SparkNotes LLC, 2015. [Online]. Available:
http://www.sparknotes.com/physics/oscillations/review/terms.html.
[7] I. Poole, "Radio-Electronics.com," Adrio Communications Ltd, [Online]. Available:
http://www.radio-electronics.com/info/circuits/opamp_basics/operational-amplifier-
gain.php.
[8] "CSGNetwork," Copyscape, [Online]. Available:
http://www.csgnetwork.com/ohmslaw2.html.
[9] "Index Mundi," Index Mundi, 30 June 2015. [Online]. Available:
(http://www.indexmundi.com/philippines/electricity_consumption.html.
[1
0]
"eBay," eBay, March 2014. [Online]. Available: http://www.ebay.com/gds/What-is-the-
Difference-Between-Floor-Mats-and-Floor-Liners-/10000000177404865/g.html.
[1
1]
J. Lewitin, "About Home," About.com, [Online]. Available:
http://flooring.about.com/od/Flooring-Pros-And-Cons/a/Rubber-Flooring-Tiles-The-Price-
Of-Durability.htm.
[1
2]
"NDT Resource Center," 2009. [Online]. Available: https://www.nde-
ed.org/EducationResources/CommunityCollege/Ultrasonics/EquipmentTrans/piezotransd
ucers.htm.
[1
3]
S. Ankur and T. Pramathesh, "Piezoelectric Crystals : Future Source of Electricity,"
International Journal of Scientific Engineering and Technology, vol. II, no. 4, pp. 260-262,
2013.
50
[1
4]
M. Oswal, J. Paul and R. Zhao, "A Comparative Study of Lithium - Ion Batteries," University
of Southern California, California.
[1
5]
T. L. Floyd, Electronics Devices, New Jersey: Prentice Hall, 2012.
[1
6]
"electrical4u.com," electrical4u, [Online]. Available:
http://www.electrical4u.com/chopper-dc-to-dc-converter/. [Accessed October 2015].
[1
7]
"Springs and Things Inc," Spring Manufacturers Institute, [Online]. Available:
http://www.springsandthings.com/pdf/Compression-new.pdf. [Accessed October 2015].
[1
8]
"Energy Harvesting Forum," www.energyharvesting.net, [Online]. Available:
http://www.energyharvesting.net/. [Accessed 6 October 2015].
[1
9]
"Mtholyoke," Mtholyoke.edu, [Online]. Available:
http://www.mtholyoke.edu/~walch20l/classweb/wp/prosandcons.html. [Accessed 6
October 2015].
[2
0]
C. Woodford, "Explain that Stuff!," 2009. [Online]. Available:
http://www.explainthatstuff.com/piezoelectricity.html. [Accessed 6 October 2015].
[2
1]
"Nanomotion," Johnson Electric, [Online]. Available: http://www.nanomotion.com/piezo-
ceramic-motor-technology/piezoelectric-effect/. [Accessed 6 October 2015].
[2
2]
C. Woodford, "Piezoelectricity," 2009. [Online]. Available:
http://www.explainthatstuff.com/piezoelectricity.html.
[2
3]
"electrical4u.com," electrical4u, 2011. [Online]. Available:
http://www.electrical4u.com/ohms-law-equation-formula-and-limitation-of-ohms-law/.
[2
4]
T. Cox, "Simple Harmonic Motion," University of Salford, Manchester.
[2
5]
J. K. Roberge, "Operational Amplifiers: Theory and Practice," John Wiley & Sons Inc.,
Massachusetts, 1975.
[2
6]
J. Ryall, "Japan harnesses energy from footsteps," The Telegraph, 12 December 2008.
[2
7]
J. Zhao and Z. You, "A Shoe-Embedded Piezoelectric Energy Harvester for Wearable
Sensors," National Center for Biotechnology Information, 2014.
[2
8]
T. Dikshit, D. Shrivastava, G. Abhijeet, A. Gupta, P. Parandkar and S. Katiyal, "Energy
Harvesting via Piezoelectricity," BIJIT - BVICAM’s International Journal of Information
Technology, vol. II, 2010.
51
[2
9]
B. Doyle, "Piezoelectric Energy Harvesting," p. 9, 2012.
[3
0]
J. L. T. Besinio, N. A. D. Bustamante, M. J. V. Nicolas, A. S. Tolentino and P. G. T. Valbuena,
"In-Wheel Piezoelectric Generator For Lighting Applications of Mining Trolleys," De La Salle
University , 2011.
[3
1]
L. E. F. Altarejos, E. J. R. Apuli, M. E. G. Dela Cruz, A. J. G. Gamilla and S. R. L. Garcia, "Energy-
Harnessing Footware Using Combined Electromechanical And Piezoelectric Transducers for
Charging Supercapacitors," De La Salle University, 2009.
[3
2]
J. C. M. Hung, M. H. A. Rilles and K. B. Monillas, "Power Generation For Remote Areas
Utilizing Piezoelectric Transducers Harnessing Wind And Wave Energy," De La Salle
University, 2011.
[3
3]
"The Engineering Toolbox," [Online]. Available:
http://www.engineeringtoolbox.com/stress-strain-d_950.html.
[3
4]
"BBC," BBC, 2014. [Online]. Available:
http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/generation_transmission_el
ectricity/electrical_quantitiesrev3.shtml.
[3
5]
B. Doyle, Piezoelectric Energy Harvesting, p. 9, May 2012.
[3
6]
T. Caston, "Piezoelecctric Energy Harvesting Floor Mat," Electrical Engineering Community,
EEWEB, 2011.
[3
7]
L. Gittins, "Houstin Chronicle," Hearst Newspaper, LLC, [Online]. Available:
http://smallbusiness.chron.com/types-bluetooth-technology-58388.html.
[3
8]
N. Ismail and R. Abd Ghani, "Advance Devices Using Piezoelectric Harvesting Energy," IEEE
Xplore Digital Library, pp. 450 - 453, 2013.
[3
9]
J. Carrillo and D. Marusiak, "Energy Harvesting of Human Movement," California
Polytechnic State University , 2012.
[4
0]
"Star Trek," startrek.com, 2015. [Online]. Available: http://stattrek.com/chi-square-
test/independence.aspx?Tutorial=AP.
[4
1]
M. S. N. N. G. Monika Jain, ""VIDYUT Generation via Walking: Analysis"," International
Journal of Engineering Sciences and Resaerch Technology , Feb 2013.
52
APPENDIX A
Chi-Square Critical Values Table
Degrees of
Freedom
Probability of Exceeding the Critical Value
0.10 0.05 0.025 0.01
1 2.706 3.841 5.024 6.635
2 4.605 5.991 7.378 9.210
3 6.251 7.815 9.348 11.345
4 7.779 9.488 11.143 13.277
5 9.236 11.070 12.833 15.086
6 10.645 12.592 14.449 16.812
7 12.017 14.067 16.013 18.475
8 13.362 15.507 17.535 20.090
9 14.684 16.919 19.023 21.666
53
10 15.987 18.307 20.483 23.209
11 17.275 19.675 21.920 24.725
12 18.549 21.026 23.337 26.217
13 19.812 22.362 24.736 27.688
14 21.064 23.685 26.119 29.141
15 22.307 24.996 27.488 30.578
16 23.542 26.296 28.845 32.
17 24.769 27.587 30.191 33.409
18 25.989 28.869 31.526 34.805
19 27.204 30.144 32.852 36.191
20 28.412 31.41 34.17 37.566
54
APPENDIX B
Bill of Materials
The tabulated estimation cost of the materials that are needed for the construction
of the project are listed below:
No. Materials Price Quantity Total Price
1 Piezoelectric
Buzzer/Transducer 50.00 25 1250.0
2 Puzzle Rubber Sheets
(20in x 20in x 3in) 500.00 10 5,000.00
3 Stainless Steel
(15in x 1in x 1in) 2,500.00 1 2,500.00
4 Vinyl Tile 80.00 8 640.00
5
Banana Jacks (Female) and
Plug (Male)
150.00
150.00
4 pairs (8 pieces)
Banana Jacks
4 pairs (8 pieces)
Banana Plugs
1,200.00
6 Small Compression Spring 75.00/pack 100 150.00
7 Big Compression Spring 80.00/pack 20 80.00
8 Diodes
(1N4001) 10.00 20 200.00
9 Capacitors
(470uF, 25V) 6.00 2 12.00
10 Chopper 1,000.00 1 1,000.00
11 Energy meter 5,000.00 1 5,000.00
12 Lithium – ion Battery
(3.7V) 575.00 1 575.00
13 PCB and Developer 90.00 4 360.00
14 Ferric Chloride 40 1 40.00
TOTAL 18,007.00
55
APPENDIX C
Gantt Chart
This table provides the chart illustration of the researcher’s Project Study 1
schedule which enables the researchers to coordinate and track specific activities and
tasks.
56
APPENDIX D
Average Weight of Students in FEU-Institute of Technology
57
58
59
60
APPENDIX E
Data of Average Students that Entered the School Premises
Date Number of Students that
Entered the School
Premises
2015-08-25 744
2015-08-26 6,075
2015-08-28 6,288
2015-08-29 4,834
2015-09-01 5,715
2015-09-02 4,352
2015-09-03 5,484
2015-09-04 5,412
2015-09-05 4,066
2015-09-07 4,882
61
2015-09-08 5,335
2015-09-09 4,620
2015-09-10 4,673
2015-09-11 2,445
2015-09-12 3,535
2015-09-14 4,875
2015-09-15 4,891
2015-09-16 4,016
2015-09-17 4,038
2015-09-18 3,948
2015-09-19 2,466
2015-09-21 3,628
2015-09-22 3,180
2015-09-23 3,614
2015-09-24 3,587
2015-09-26 2,750
2015-09-28 3,704
2015-09-29 2,389
2015-09-30 1,556
62
2015-09-30 1,556
2015-10-01 3,215
2015-10-03 2828
2015-10-05 2,320
2015-10-06 2,377
2015-10-07 1,684
2015-10-08 1,789
2015-10-09 1,691
2015-10-10 1,565
2015-10-12 1,401
2015-10-13 1,040
2015-10-14 522
2015-10-15 837
2015-10-16 4,030
2015-10-17 4,073
2015-10-20 4,256
2015-10-21 3,502
2015-10-22 2,080
2015-10-23 3,794
63
2015-10-24 345
2015-10-26 1,334
2015-10-27 3,987
2015-10-28 2,793
2015-10-29 1,656
2015-10-30 1,678
2015-11-02 5,816
2015-11-03 5,953
2015-11-04 6,445
2015-11-05 8,109
2015-11-06 7,158
2015-11-07 5,123
2015-11-09 7,103
2015-11-10 6,698
2015-11-11 5,430
2015-11-12 6,048
2015-11-13 5,672
2015-11-14 3,729
APPENDIX F
CONSULTATION SHEET
Project Study 1
Members:
CAPATI, Aubrey Sharmaine M. Engr. Luigi Carlo M. De Jesus
MAGLUYAN, Pamela Kim Donnelle G. Adviser
POSTRE, Raul Christian M.
DATE TIME ACTIVITY SIGNATURE
08 – 20 – 15 18:00 – 19:00 Chapter __ : Consultation
08 – 24 – 15 14:30 – 15:00 Chapter __ : Consultation
08 – 27 – 15 16:00 – 16:30 Chapter __ : Consultation
09 – 02 – 15 13:30 – 14:00 Chapter __ : Consultation
09 – 06 – 15 12:30 – 14:00 Chapter __ : Consultation
09 – 07 – 15 16:10 – 17:35 Chapter __ : Consultation
09 – 10 – 15 15:40 – 16:00 Chapter __ : Consultation
09 – 11 – 15 16:40 – 16:55 Chapter __ : Consultation
09 – 16 – 15 13:45 – 15:00 Chapter __ : Consultation
09 – 21 – 15 13:10 – 13:30 Chapter __ : Consultation
09 – 22 – 15 13:50 – 14:30 Chapter __ : Consultation
09 – 24 – 15 13:10 – 13:50 Chapter __ : Consultation
09 – 30 – 15 10:42 – 11:05 Chapter __ : Consultation
10 – 03 – 15 12:40 – 13:15 Chapter __ : Consultation
10 – 08 – 15 13:40 – 14:35 Chapter __ : Consultation
10 – 12 – 15 13:15 – 14:10 Chapter __ : Consultation