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Energy Harvesting from Human Locomotion using
Piezoelectric Transducer-Based Shoe
M. Tanseer Ali, Tahsin Jahin Khalid, Abid Ahmed, Noor-E-Rashid Saabiq-Un and Moliat Rezuana Nancy
Dept. of EEE, Faculty of Engineering
American International University - Bangladesh
Dhaka, Bangladesh
email: tanseerali@gmail.com
Abstract— In this paper a proposed design of a piezoelectric
transducer-based energy harvesting device has been presented.
The primary goal of the research was to develop a device that
can charge up the batteries of smartphones or other small-scale
gadgets using the energy from human locomotion. The
operation of our charging device involves the conversion of the
mechanical stress produced in the transducer plates by human
footsteps during walking, sprinting, etc. into alternating current
and voltage which is then rectified and adjusted by electronic
circuit combinations to meet the direct current and voltage
requirements for replenishing the battery charge.
Keywords — Energy Harvester, Piezoelectric Transducer,
Energy Conversion, Sustainable Energy, Green Energy,
Renewable Energy;
I. I
NTRODUCTION
(H
EADING
1)
In the present era, technology plays a predominant role in
the daily lives of human beings. One multipurpose device that
has resulted from years of innovation and research is the
mobile phone, or the smartphone. Due to the increased
dependency on the smartphones in our daily routines, it can be
seen that the battery level on the devices depletes rather
rapidly, usually lasting around 5 hours at most. This causes the
problem of frequently re-charging the batteries. Most of the
devices we utilize every day usually last a day on a full charge
and thus, finding ways of feeding their battery cells can be
demanding. The most obvious method of charging is the
charger but the availability of sockets is not always favorable.
An alternate is the power-bank, which is a remedy to this
problem but not an absolute one as it sometimes disappoints
when it is needed the most.
According to a 2009 report by the International Energy
Agency (IEA), consumer electronics and information and
communication technologies currently account for nearly 15
percent of global residential electricity consumption.[1] In
addition to that, according to the report [1] the expected
energy consumptions by these devices to 1700 Terawatt hours
(TWh) by 2030 — thereby slowly but surely adding to the
burden on our power infrastructure. In the case of the
developed nations such as the G8 (Group of Eight) countries,
they may arrange the frequent availability of charging outlets
for smartphones and similar devices such as tablets, laptops,
etc. However, considering the other parts of the world which
are still undergoing development, such a charging
groundwork is not feasible or sustainable as the power grid
may not be stable or available at every part of the world.
The gadget recharging through movement is an area of
applied sciences where electrical energy can be reaped from
the human body via the application of different methods. This
harvestable potential energy is wasted. However, by applying
this technology, we can convert a prominent portion of the
wasted energy into electrical energy for charging the batteries
of smartphones or other similar devices.
A good number of research works [2 – 6] have been done
in energy harvesting from human locomotion. Most of these
research work and testing has been done with instantaneous or
periodic power generation, compared to this research work
AC-DC conversion and DC-DC booster has been added to get
stabilized power output. In this research work a protype
energy harvester device has been developed and tested which
has been designed based on Piezoelectric Transducer. For
efficient energy conversion the device has been developed in
a wearable shoe, from where smart phones or small devices
can be charged.
II. M
ETHODOLOGY
A. Working Principle:
The overall working principle of the proposed energy
harvester has been presented in figure 1. The proposed design
of the Energy Harvester Shoe is to integrate a series of
piezoelectric transducer plates into the sole. The positive and
negative common points are taken and the wires are connected
to a bridge-rectifier circuit for converting the generated
alternating current (AC) to Direct current (DC).
Fig. 1. Block diagram of the proposed Energy Harvester
The output wires from the rectifier are connected to a boost
regulator which boosts the DC voltage with the help from an
inductor, the output from the boost converter is connected to
a voltage regulator which will produce a steady voltage of
~5V and ~1A which is convenient for charging any small
device such as a smartphone.
B. Structural Design
Initially, the structural design of the sole of the
prototype is finalized using CAD. The purpose of this step is
to develop an explicit imagery on her the prototype’s
scaffolding should appear as figure 1. As the CAD design
exhibits in figure 2, twelve piezoelectric transducer plates
have been arranged in series connection systematically on the
sole in a manner that areas of pressure exertion are maximized.
Fig. 2. Design of the Shoe Sole with Piezoelectric Transducers
C. Circuit Simulation
Due to the nature of the components involved in the
project, the simulation has been done using Proteus 8.7 and a
PCB layout has been made using the same software. The
schematics of the circuit is shown in figure 3.
Fig. 3. Schematic diagram of the circuit of the proposed energy harvester.
For a boost regulator, the average output voltage, average
output current, Peak-to-peak ripple voltage and current can be
stated as following equations.[7]
||
... (1)
|1
|
... (2)
∆
∗
|∗|
... (3)
∆
∗
|∗|
... (4)
Where, V
a
is the average output voltage, k is a constant (the
duty cycle expressed as a ratio) and V
s
is the source voltage; I
a
refers to the average output current and I
s
is the source current.
Also, f is the switching frequency, L is the magnitude of
inductance and C is the magnitude of the capacitance. The
power can be calculated from the output voltage and current.
The piezoelectric transducer plate has been simulated with
an AC source at 1.9V and 1.5 Hz as the electricity generation
of the transducer is dependent on the person’s walking speed.
The 555 timer serves the purpose of the switching device of
the boost regulator circuit. The output of the boost regulator
has been passed through a voltage regulator L7805 so that
output is kept at ~5V and ~1A, which is sufficient for
charging.
III. I
MPLEMENTATION
The implementation of designed circuitry in the shoe was
critical and it has been done with delicate placing of the
components on the boot without damaging any components.
Figure 4 shows the sole with 12 piezoelectric plates and figure
5 shows the complete shoe with circuits.
Fig. 4. Piezoelectric Transducer Sole
Fig. 5. Side-View of the Prototype with/without Protective Cover
A small switch has been included in the prototype to turn
the power ON or OFF. From Figure 4.7, it has been observed
that most of the wires and components are hidden from view
using the opaque cover. The cover also provides protection
from any minor damages.
IV. R
ESULTS AND
A
NALYSIS
A. Simulation results
Values for voltage, current and power were obtained from
the simulated circuit using Proteus 8.7. The results have been
tabulated in table I and graphs have been shown in figure 6.
TABLE I. S
IMULATION
R
ESULTS OF THE
B
OOST
R
EGULATOR
Input
Voltage
Vs (V)
Output
Voltage
Va (V)
Output
Current
I (mA)
2.2 0.88 -
2.4 4.48 11.14
2.6 17.0 22.02
2.8 17.0 23.38
3.0 14.4 23.76
3.2 13.3 24.30
3.4 12.7 24.90
3.8 12.1 26.07
Fig. 6. Input Voltage vs Output Voltage & Current (Simulated)
From the graph of output voltage against input voltage, it
can be observed that the output from the boost-regulator has a
peak when the input voltage is around 2.7 V. It can also be
seen that further increments of the input voltage will initially
cause the output current from the boost-regulator to climb
rapidly as exhibited by the steep gradient and then increase
gradually.
It can be deduced that the output power exhibits a peak
from a steep climb when the input voltage is at 2.7 V and then
the output power gradually decreases for further increments in
input voltage until it settles at around 315 mW. The Voltage
Regulator L7805 component has been implemented after the
boost regulator which ensures that the output voltage is always
at 5.0 V and the output current is always at 1.0 A regardless of
the current entering and the voltage across the component.
B. Practical Results
The prototype device was implemented and utilized in a
transient analysis demonstration to determine the variation of
output voltage, output current and output power over a period
of one hour. The procedure was iterated several times and
averaged values for the output voltage and current were
tabulated in Table II.
From the data, it can be observed that the output current
has stayed fixated on the value of 0.6 A or 600 mA. This is
because of the resistance of the wiring and internal resistances
in the LM2577 module, which consists of the boost-regulator
and the voltage regulator LM7805.
TABLE II. T
RANSIENT
A
NALYSIS OF THE
P
ROTOTYPE
Time
(mins)
Output
Current
(A)
Output
Voltage
(V)
Output
Power
(W)
5 0.6 4.96 2.976
10 0.6 4.93 2.958
15 0.6 4.97 2.982
20 0.6 4.95 2.970
25 0.6 4.93 2.958
30 0.6 4.94 2.964
35 0.6 4.93 2.958
40 0.6 4.96 2.976
45 0.6 4.97 2.982
50 0.6 4.96 2.976
55 0.6 4.94 2.964
60 0.6 4.93 2.958
Fig. 7. Output Voltage against Time
Fig. 8. Output Power against Time
From the graph in figure 7, it can be discerned that the
output voltage varies within the range from 4.93 V to 5.00 V,
with the maximum-recorded value being 4.97 V. From the
graph in figure 8, it can be perceived that the output power
from the implemented project prototype can be almost as high
as 3 W.
The device had been used in jogging for an hour and was
subsequently utilized to charge the 4000 mAh battery of a
smartphone. Considering the equation E = I*V*t and the
values of E = 4000 mAh, I = 0.6 A and V = 4.93, we can
calculate the time taken to fully charge such a battery using
our device in 81 mins.
The initial charge of the battery was 12% and after having
been charged for 38 minutes, the battery level had risen to
23%. For an 11% increase in battery charge level at 600 mA
current and 4.90 V voltage, the time taken was 38 minutes.
Assuming the current and voltage outputs stay at 600 mA and
4.90 V respectively, we can estimate that for 1% increment in
charge level, the time taken would be 3.45 mins. Therefore,
the time taken to fully charge the battery using the prototype
345 mins or 5.75 hr. It can be seen that to fully charge the
0
5
10
15
20
25
30
2.4 2.6 2.8 3 3.2 3.4 3.8
Input Voltage (V)
Output Voltage (V)
Output Current (mA)
4.91
4.92
4.93
4.94
4.95
4.96
4.97
4.98
5 1015202530354045505560
Time (min)
Output Voltage (V)
2.94
2.95
2.96
2.97
2.98
2.99
5 1015202530354045505560
Time (min)
Output Power (W)
smartphone battery, around 6 hours of constant
running/jogging/walking with the device has to be employed.
Such a feat is not achievable by humans. Thus, it can be
concluded that the device should be used intermittently.
V. C
ONCLUSION
Comparing the simulation results with the ones which
have been obtained from the practical implementation of the
project prototype model, it can be seen that the actual realistic
values are not amounting to that specified in the LM2577’s
data-sheet. The actual voltage output is within an acceptable
range (4.93 – 5.00 V) however, the current is at 600 mA and
not at 1.00 A as it was intended to be.
Even after the limitation, the developed prototype showed
promising results with up to 3W continuous power supply
while walking. Compered to similar research works, the
results were promising and efficient to transfer to real product
manufacturing.
This proposed design will be beneficial to both the society
and the environment, as it provides a solution to the problem
of rapidly decreasing battery charge of smartphones by
charging them on-the-go, and it uses a source of energy that is
renewable and produces no wastage.
R
EFERENCES
[1] “IEA expects energy use by new electronic devices to triple by 2030
but sees considerable room for more efficiency” IEA. Paris — 13 May
2009, [Online] Accessed: 29/10/2019; Available at:
https://www.iea.org/newsroom/news/2009/may/2009-05-13-.html
[2] M. Jain, U. Tiwari and M. Gupta, "Mobile charger via walk," 2011
International Conference on Multimedia, Signal Processing and
Communication Technologies, Aligarh, 2011, pp. 149-152.
doi: 10.1109/MSPCT.2011.6150461.
[3] Can-Fei Wang, Dong-Min Miao, P. C. Luk, Jian-Xin Shen, Chi Xu and
Dan Shi, "A shoe-equipped linear generator for energy harvesting,"
2010 IEEE International Conference on Sustainable Energy
Technologies (ICSET), Kandy, 2010, pp. 1-6. doi:
10.1109/ICSET.2010.5684934
[4] G. Colso n, P. La urent , P. Bellier, S. Stoukatch, F. Dupo nt a nd M. Kr aft,
"Smart-shoe self-powered by walking," 2017 IEEE 14th International
Conference on Wearable and Implantable Body Sensor Networks
(BSN), Eindhoven, 2017, pp. 35-38. doi: 10.1109/BSN.2017.7936001
[5] J. N. S. Quispe and A. C. Gordillo, "Implementation of an energy
harvesting system by piezoelectric elements exploiting the human
footsteps," 2017 IEEE URUCON, Montevideo, 2017, pp. 1-4. doi:
10.1109/URUCON.2017.8171873
[6] Snehalika and M. U. Bhasker, "Piezoelectric Energy harvesting from
shoes of Soldier," 2016 IEEE 1st International Conference on Power
Electronics, Intelligent Control and Energy Systems (ICPEICES),
Delhi, 2016, pp. 1-5. doi: 10.1109/ICPEICES.2016.7853116
[7] “What is Boost Converter?” [Online] [accessed on: May 10th, 2019]
available at: https://components101.com/articles/boost-converter-
basics-working-design
[8] Datasheet, “LM1577/LM2577 SIMPLE SWITCHER® Step-Up
Voltage Regulator”, Texas Instruments Incorporated, June 1999 –
Revised April 2013. [Online] ] [accessed on: May 10th, 2019] available
at: http://www.ti.com/
