1. INTRODUCTION In recent years, energy harvesting fro.docx

1. INTRODUCTION
In recent years, energy harvesting from ambient vibration [I and
human motion [2] has received both considerable industrial and
academic interest due to advances in micro-electronic
technology leading to an increased computation efficiency and
reduced power consumption of wireless sensors and portable
electronic devices. In addition to environmental benefits
associated with limiting the disposal of traditional batteries,
energy harvesting technologies [3] provide a great promising of
autonomous and self-powered electronic devices for safety
monitoring, structure-embedded diagnosis and medical
implants. The narrowband issues of linear resonant piezoelectric
energy harvesters have motivated several research groups to
develop the nonlinear monostable [4], bistable [5] and tristable
[6] approaches to enhance frequency bandwidth and output
power. The theoretical analysis and experimental verification of
those nonlinear energy harvesters have been extensively
investigated under harmonic and stochastic excitations [7-9].
For the realistic excitation, Green [2] numerically analyzed the
efficiency of nonlinear energy harvesting from human motion
and Cao [10] applied the time-varying potential bistable energy
harvester to human motion to demonstrate its better
performance than the linear one. However, tristable energy
harvesting performance has not yet been evaluated under
realistic excitations induced by human motions. Therefore, the
paper employs tristable magnetic coupled piezoelectric
cantilever to harvest energy from human walking and running.
Based on the characteristics of human motion, theoretical model
of nonlinear tristable energy harvester with time-varying

potential energy function is established. And experiment results
show that the tristable energy harvester exhibits better
performance than the linear one when applied to harvesting
energy from human walking and running.
2. ELEC TROMECHANICAL MODEL
The magnetic coupled piezoelectric energy harvester with
external magnets is illustrated in Fig.1 (a). The configuration
consists of a stainless steel substrate, two symmetric PZT-51
piezoelectric layers at the root, tip magnet attachments and two
external magnets.
Tristable energy harvester can be obtained by adjusting the
parameters h, d and a.When harvester is applied to harvesting
energy from human motion , the lower limb swing motion will
drive the cantilever to swing a certain angle (shown in Fig.1 (b)
which results in a time-varying potential energy function due of
the beam. On these conditions, the electromechanical model of
the nonlinear piezoelectric energy harvesters with time-varying
potential energy function can be given by the following
equation:
Where m is the equivalent mass and c is the equivalent
damping. 0 is the equivalent electromechanical coupling
coefficient, Cp is the equivalent capacitance of the piezoelectric
materials, R is the load resistance, v(t) is the voltage across the
electrical load, x() is tip displacement of the harvester in the
transverse direction, B(t) is the swing angle of the human leg
and al) is the external excitation. (x, B)) is the time-varying
potential energy function described as the integral of nonlinear
restoring force depending on structural parameters and the
swing angle Bt) shown in Fig.1 (b). It is found that the time-
varying potential energy function mainly attributes to the
gravity effect under different sway angles where the magnetic
force similar B 0. Therefore, the restoring force of the nonlinear

harvester can be approximated by
Where Fis the restoring force for B 0. The time-varying
potential energy function in Equation. (1) is:
In this paper it is assumed that the clockwise angle is positive
otherwise negative.
3. EXPERIMENTAL VERIFICATION
In the experiment, the energy harvester is tied to human leg for
harvesting energy from human motion as shown in Fig.2. An
acceleration sensor (CXL04GP3) and an angle sensor (BWD-
VG100) are used to collect the acceleration and swing angle
data. A displacement sensor (HL-GI) is applied to measure the
tip displacement of the cantilever. All the measured data
are acquired by an oscilloscope (MSOX3052A) with 10 M2
resistance. The cantilever is made of stainless steel of
90x10x0.27 mm3. Two PZT-51 have dimension of 12x10x0.6
mm3. All the magnets used in the experiment are NdFeB
cylinder magnets and the endmost ones have the dimension of
8x6x4 mm3 while the external magnets have diameter of 25 mm,
and has the dimension thickness of 5 mm.
A tristable energy harvester (TEH) with three stable equilibrium
points is adjusted to harvest energy from human motion and the
traditional linear energy harvester (LEH) is used to compare. In
the experiment, the restoring forces of the cantilever are
measured by the system Mark-10 and the fitted curve is plotted
in Fig. 3 while the corresponding potential energy functions
are illustrated in Fig.4. The asymmetry in the potential energy
function can be viewed as due to imperfections caused by the
evenly distributed material and structure or eccentricity of
magnetic force.
In the experiment, the nonlinear restoring forces of tristable
harvester at different swing angle+11 and +31o are measured to
demonstrate the time-varying potential energy function and the
corresponding potential energy functions are plotted in Fig. 5
and Fig. 6. When the swing angle is negative, the left potential

well depth increase while the right one becomes shallow and in
this condition the potential well in the middle does not
disappear. When the swing angles are 11o and 31°, the left
potential well depth decreases while the right increases
gradually. Moreover, the potential well in the middle disappears
when the swing angle is 31°. Furthermore, larger swing angle
has greater influence on the potential well than small angle.
Obviously, when the tristable harvester is applied to human
limb, the swing motion will greatly increase the harvesting
efficiency.
One participant (weight: 63Kg; Height: 175cm) asked to walk or
run at the speed of 4-9 km/h on treadmill the motion
acceleration, swing angle, output voltage and tip displacement.
The acceleration and swing angle data for speed 5 km/h are
shown in Fig.7. It can be seen the amplitude of the acceleration
reach about 2g and it exhibits maximum value when the foot
strikes the treadmill. For the swing motion, the lower limb
swing about 60° to backward and 15° to the forward.
experimental results show that the acceleration and swing angle
range increase with the increasing of the motion speed. The tip
displacement and voltage response as well as the frequency
spectrum at the speed of 5 km/h are illustrated in Fig.8. The
tristable harvester could travels across the potential well
frequently and does large amplitude inter-well motion between
the three stable equilibrium points because of the leg swing
motion strike, thus generates large output voltage. Furthermore,
frequency spectrum in Fig.8 shows that the response frequency
ranges from 4 Hz to 8 Hz which is probably due to the nonlinear
restoring force. The average output power of the tristable and
linear energy harvesters different motion speed are shown in
Fig.9. It can be found that the tristable energy harvester
performs better than the linear one at any motion speed.
Further, the average output power increases with the increasing
of the motion speed and the maximum average output power of
the tristable energy harvester is 16.38uW.

4. CONCLUSION
The electromechanical model of the tristable energy harvester
with time-varying potential energy function is proposed based
on the characteristics of human motion. Detailed restoring
forces of the tristable energy harvester under different swing
angles are measured and the corresponding potential energy
functions are obtained. Further, a measurement system is setup
to collect the acceleration, swing angle as well as the voltage
data generated during human motion, experimental results under
various motion speeds show that the tristable energy harvester
exhibits better performance than the linear one for harvesting
vibration energy from human walking or running.
ACKNOWLEDGEMENTS
This research is supported by National Natural Science
Foundation of China (Grant No. 51421004, 51575426), National
Key Scientific Instrument and Equipment Development Project
(No: 2012YQ03026101), Program for New Century Excellent
Talents in University (Grant No. NCET-12-0453), and
Fundamental Research Funds For the central universities of
China (Grant No. CXTD2014001).
MITRE. (2017). System design and development. System
Engineering Guide. Retrieve
from https://www.mitre.org/publications/systems-engineering-
guide/se-lifecycle-building-blocks/system-design-and-
development
MITRE. (2017). Assess the design's ability to meet the system
requirements. Retrieved
from https://www.mitre.org/publications/systems-engineering-
guide/se-lifecycle-building-blocks/system-design-and-
development/assess-the-designs-ability-to-meet-the-system-
requirements

Software Testing. (2017). Difference between system testing vs
integration testing? Retrieved
from http://www.softwaretestingclass.com/difference-between-
system-testing-vs-integration-testing/
Software Testing. (2017). User acceptance testing: What? why?
& how? Retrieved
from http://www.softwaretestingclass.com/user-acceptance-
testing-what-why-how/
Thakur, D. Software maintenance in software engineering.
(2017). Computer Notes. Retrieved
from http://ecomputernotes.com/software-engineering/types-of-
software-maintenance
Udacity. (2015, February 23). Maintenance - Georgia Tech -
software development process [video file]. Retrieved
from https://www.youtube.com/watch?v=0Y8YLMJ3ERw
QEAD Rev:03 ver
01 9th July 2017 Template A
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F/QAP/021/001
Name of the programme BEng (GCU) CAME, MT, POM, EE,
CO, EPE, TE
Name of Module with Code Research Methodology,
MHH124715
Level/Semester & AY Level 4/Semester A 2018-19
Name of the Module

Leader/Tutor
Dr. Dinesh Keloth kaithari and Dr. K. Suresh Manic / Mr.Ali
Abdullah Hamed Al-Mahruqi and Dr.Vijayalakshmi K.
Coursework Type Research Methods
Assessment weightage 25 % of Overall Assessment
Type and date of submission Online 08
th November 2018
Methods & achievement of learning outcomes of
the module with respect to the abilities to critically
analyse technical papers, interpret scientific &
technical data, proper referencing and citation of
the literature.
ives of
project
topic
Tasks
Task-1: A technical paper will be given to the student by his/her
Project Supervisor and he/she
will be required to write a critical analysis and an abstract
based on the scientific information

available in the paper.
[70 marks (Abstract writing: 30 Marks & Critical Analysis
Writing: 40 marks)]
Abstract:
The Abstract must contain description of the topic, important
applications of the topic, brief
description about previous literature present in the paper,
methodology adopted by the author,
important results obtained and conclusions derived from the
results. The word count is limited to
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abstract.
CONTENT MAX MARKS
ABSTRACT DEVELOPMENT 20
WRITING QUALITY, LOGICAL AND FOCUSED 5
BASIC GRAMMAR, SPELLING AND OTHER CONVENTIONS
5
TOTAL 30

QEAD Rev:03 ver
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F/QAP/021/001
Critical Analysis: With the introduction to the topic, students
are expected to critically analyze
the literature part that contains key findings of previous
authors, methodology adopted in given
paper, parameters used for analysis, analyze the results obtained
(from graphs/tables),
important conclusions derived based on the result, weaknesses
in the paper and scope of
further investigations identified. Each topic has to be separately
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of 500 to 750.
TASK-2: Visit the Library & Resource Center, e-brary and
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and prepare the reference in CCE-Harvard referencing style.

There must be: 2 Library books or E-library books, 5 Journal or
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1 Image in Book.
Suggestive format for the Task 2
S.No Type of
Resource
Citation (In-text) –CCE
Harvard Style
Reference List Entry
1. Journal
Paper
…………….. ……………………..
2. Book ………. ……………………
3. Website ……. …………………………
4 Image in
Book

CONTENT MAX MARKS
DOES THE WORK SHOW AN UNDERSTANDING OF
TECHNICAL CONTENTS OF THE PAPER?
5
COULD THE STUDENT CLEARLY IDENTIFY THE
OBJECTIVE OF THE PAPER AND RELATE THAT
TO OTHER EARLIER WORKS CITED IN THE PAPER?
10
DID THE STUDENT ARGUE / EVALUATE THE METHODS /
TECHNIQUES USED BY THE AUTHORS
OF THE PAPER?
15
COULD THE STUDENT IDENTIFY ANY WEAKNESSES IN
THE PAPER? 5
IS ANY SCOPE FOR FURTHER INVESTIGATION
IDENTIFIED BY THE STUDENT? 5
TOTAL 40
CONTENT MAX MARKS
In text Citations
For the ten citations, 1 mark each for correct in-text citations
10x1 = 10

References
For the corresponding 10 References, 2 mark each for correct
listing of
references to confirm to the CCE- Harvard Referencing style.
10x2 = 20
TOTAL 30
QEAD Rev:03 ver
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F/QAP/021/001
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of the topic
30%
2 Application and analysis of the
topic (Module specific Skill)

35%
3 The structure in terms of logic
and coherence
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examples and/or examples
gained from further reading
5%
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Harvard Referencing (CCE Style) First Edition 2013 should be
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Name and Signature of Module leader
Dr. Dinesh keloth kaithari and Dr. K. Suresh Manic
Date: 08-07-2018
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QEAD Rev:03 ver
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Research Methodology – CW1 (25% overall)
Task.1 (70% OF CW1)
CRTICAL REVIEW OF TECHNICAL PAPER - MARKING
SHEET
STUDENT’S NAME
_____________________________________________________
_________

STUDENT NO: _________________ PROGRAMME:
____________________
PROJECT TITLE:
_____________________________________________________
___________
* Please ✓ the option and assign the marks appropriately in the
‘Marks’ column.
ABSTRACT
(30 MARKS)
O
U
T
S
T
A
N
D
IN
G
(9
0
-1
0
0

)
E
X
C
E
L
L
E
N
T
(8
0
-8
9
)
V
E
R
Y
G
O
O
D

(7
0
-7
9
)
G
O
O
D
(6
0
-6
9
)
S
A
T
IS
F
A
C
T
O
R

Y
(5
0
-5
9
)
F
A
IL
(
<
5
0
%
)
M
A
R
K
S
ABSTRACT DEVELOPMENT

/20
WRITING QUALITY: LOGICAL AND FOCUSED
/5
BASIC GRAMMAR, SPELLING AND OTHER
CONVENTIONS.
/5
CRITICAL ANALYSIS
(40 MARKS)
O
U
T
S
T
A
N
D
IN
G

(9
0
-1
0
0
)
E
X
C
E
L
L
E
N
T
(8
0
-8
9
)
V
E
R
Y

G
O
O
D
(7
0
-7
9
)
G
O
O
D
(6
0
-6
9
)
S
A
T
IS
F

A
C
T
O
R
Y
(5
0
-5
9
)
F
A
IL
(
<
5
0
%
)
M
A

R
K
S
DOES THE WORK SHOW AN UNDERSTANDING OF
TECHNICAL CONTENTS OF THE PAPER?
/5
COULD THE STUDENT CLEARLY IDENTIFY THE
OBJECTIVE OF THE PAPER AND RELATE THAT TO
OTHER EARLIER WORKS CITED IN THE PAPER?
/10
DID THE STUDENT ARGUE / EVALUATE THE
METHODS / TECHNIQUES USED BY THE AUTHORS
OF THE PAPER?
/15
COULD THE STUDENT IDENTIFY ANY
WEAKNESSES IN THE PAPER?
/5
IS ANY SCOPE FOR FURTHER INVESTIGATION
IDENTIFIED BY THE STUDENT?
/5

TOTAL MARKS (TASK 1)
/70
SIGN AND NAME OF THE MARKER
QEAD Rev:03 ver
5
F/QAP/021/001
Task 2 (30% OF CW1)
REFERENCING MARKING SHEET
STUDENT’S NAME
_____________________________________________________
_________
STUDENT NO: _________________ PROGRAMME:
____________________
PROJECT TITLE:
_____________________________________________________
___________

Description Marks
In text Citations
For the ten citations as per CW1 guidelines, 1 mark each for
correct in-
text citations as per CCE- Harvard Referencing style
(10x1=10marks)
/10
References
For the corresponding 10 References as per CW1 guidelines, 2
mark
each for correct listing of references to confirm to the CCE-
Harvard
Referencing style.
(10x2 = 20marks)
/20
TOTAL MARKS(Task 2) /30
TOTAL MARKS (TASK 1 = …………..+ TASK 2=………….)
/100

COMMENTS:
SIGN AND NAME OF THE MARKER

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