22nd ASEMEP National Technical Symposium
ENERGY CONTRAPTION DESIGN USING PLAYGROUND SEESAW FOR
LIGTHING LOAD APPLICATIONS
John Ray B. Abad
Merryll D. Capucao
Lynette Dane C. Legaspi
Department of Electrical, Electronics and Computer Engineering
Mapua Institute of Technology, Muralla, Intramuros, Manila
[email protected], [email protected], [email protected]
ABSTRACT
Energy contraption is widely used to produce
electricity by transforming different kinds of energy into
electrical. One of the sources of energy contraption is from
everyday human activities. The playground is used everyday
by children and produces motion which can be converted to
electrical energy. This study is about conversion of motion
by children playing seesaw and storing it to a battery for
future use. Using pneumatic principle, the mechanical
energy from the motion of the seesaw is converted using the
pneumatic principles. With the utilization of the
microcontroller, the energy collected will be stored in the
battery and will stop the charging once the battery is full.
The energy that is stored in the battery will supply mainly
lighting loads.
1. 0 INTRODUCTION
People are in search of renewable sources of energy
nowadays. With increasing demand and decreasing
resources, many seek new ways of converting different
forms of energy to electrical energy. Contraption is a way in
which a strange machine or apparatus is invented for a
particular purpose Energy contraption nowadays has many
applications in small scale or large scale. With further
studies, it may be used to create a major source of renewable
energy.
By harnessing human power from the children playing in
the playground, energy contraption could be further applied
specifically in seesaw, merry-go-round, and swing. The
mechanical energy produced by children’s play can useful
and harnessed resulting to significant energy storage.
According to Pandian(2004), the stored energy can be
converted to electricity for powering basic, low-power
appliances such a lights, fans and the like [1]. The concept
of this study is the creation of a prototype of a seesaw to
generate power through pneumatics.
This study aimed to:
1. Design a prototype
1
2. Test the speed of compression of air from the
pneumatic cylinders.
3. Determine the charging and discharging time of the
battery
4. Design a controller circuit for the state of change of the
batteries.
The study aimed to provide free lighting to playgrounds,
parks and rural areas. Using the energy generated by
seesaw, the energy from children’s play will be converted
into usable energy. If this will be implemented to many
parks and playground there will be great power savings.
This will introduce a new source of renewable energy
especially in this country.
The scope of this study is the generation of DC power by
means of mechanical motion by the use of pneumatic
cylinder installed in the seesaw. It will produce a small
amount of power due to limited motion of the seesaw that is
intended to supply only small lighting loads, particularly
LED’s(Light Emitting Diodes). The study focused on the
usage of seesaw as the medium of the pneumatic cylinders
and not in other playground equipment such a merry-gorounds and swings. Battery will be used as a storage device
and the amplification of the energy stored will not be
covered by the study.
2. 0 REVIEW OF RELATED LITERATURE
Pandian (2004) conducted a study about Human Power
Conversion System based on children’s play. It proposed a
new method for harnessing human power based on
children’s play in playground and public places, and on
devices such as seesaw, merry-go-round, and swing [1].
When large number of children play in playground, part of
the power of their play can be usefully harnessed resulting
to significant energy storage. This stored energy can then be
converted to electricity for powering basic, low-power
appliances such as lights, fans, communications equipment,
and so on. The method provides a low-cost, low-resource
means of generation of electricity, especially for use in
developing countries. The paper discussed the basic theory
22nd ASEMEP National Technical Symposium
behind the method. Results of experiments on a laboratory
prototype compressed air human power conversion system
using a teeter totter (seesaw) are presented to illustrate the
practical effectiveness of the method proposed by Pandian.
2.1 Mechanical to Electrical Conversion
Smit and Associates(2009) stated that most human-power
energy harvesting systems are used to power abundantly
deployed sensor networks and mobile electronics. These
systems scavenge power from human activity of derive
limited energy from ambient heat, light, or vibrations. In
most of these conventional methods, users must focus their
attention on power generation at the expense of other
activities. However, for suitable electrical power generation,
energy could be harvested from everyday activities such as
walking, running or even dancing. In this paper, systems
that use human power by walking of running analysed,
where an alternative system has been designed and
implemented to generate energy from people dancing in a
club environment. Its uses shown that power from walking
can be extracted using the ystem, i.e., maximum 80-100 W
to an average of 20-30 W over a period of 10 seconds. This
previous study is related to the present study because it
showed that normal human activities can be used to generate
electricity. In here, the previous researchers presented the
amount of energy that can produced by a dance floor.
Last 2008, a design student Daniel Sheridan has created a
simple seesaw which generates enough electricity to light a
classroom. The device works by transferring the power,
created by a child moving up and down on it, an electricity
storage unit via an underground cable. He has calculated
that five to ten minutes use on seesaw could generate
enough electricity enough to light a classroom for an
evening, for example. Many schools in Africa open their
doors in the evening to much older pupils but are only to
light their classrooms with candles or kerosene lamps [2].
This article discussed the feasibility of generating useful
energy from seesaw. It was used to power classrooms in the
previous design, while the present researchers will use it to
power lightings on playground.
2.2 Motor and Generator
Engineers call electric motors and generators “electrical
machines”. The reason for this more general term is the
same device may operate either as a motor or as a generator.
Electrical machines convert mechanical energy to electrical.
When conversion is from electrical mechanical, the machine
is called a motor. When it is being used to convert from
mechanical energy to electrical, the machine is called a
generator. The advantage offered by DC machines is their
versatility. The ability to develop high starting and breaking
torques, to make quick reversals of rotations, to maintain
constant mechanical power output or to maintain constant
torque and to permit continuous speed variation over a range
2
as large as 4:1, make DC motors better suited to many
industrial applications [3].
This is related to the present study because the design
will make use of motor and generator to produce electricity.
The concept of converting energy through motor and
generator is important in this study.
2.3 Pneumatic Cylinder
Pneumatic Cylinders offer a straight rectilinear motion to
mechanical elements. Cylinders are classified as light,
medium, and heavy duty with respect to their application.
Selection of materials for cylinder components may depend
greatly on this factor. Functionally, cylinders may be single
acting and double acting. The piston rod of cylinders is
given special treatment as it is a highly stressed part. For
cylinder lubrication, mist lubrication is most common. To
generate rotary motion, air motors may also be used. Vane
type motors are more popular. Air motors have certain
specific advantages over electrical motors. Proper
maintenance of cylinders, motors, and various air-operated
hand tools enhance their life expectancy to a great extent.
The pneumatic power is converted to straight line
reciprocating motions by pneumatic cylinders. A single
acting cylinder, the compressed air is fed only in one side.
Hence, this cylinder can produce work only in one direction.
The return movement of the piston is affected by a built-in
spring or by application of an external force. The spring is
designed to return the piston to its initial position with a
sufficiently high speed [4].
Figure 1. Parts of a Single Acting Pneumatic Cylinder. (1)
Cylinder(tube); (2) End Cover; (3) Piston; (4) Piston rod; (5)
U-cap seal; (6) O-ring; (7) Bush; and (8) Spring
The Pneumatic Cylinder will be used as the main
component of collecting energy from the seesaw. A single
acting cylinder will be connected to the seesaw for the
compressed air.
2.4 Energy Storage
A battery is a device that cab store energy in a chemical
form and then convert into electrical energy when needed.
There are two fundamental types of chemical storage
22nd ASEMEP National Technical Symposium
batteries: The rechargeable or secondary cell, and the nonrechargeable, or primary cell. In term of storing energy or
discharging electricity,, they are similar. Battery is
comprised of at least one but possibly many such cells
appropriately connected and these cells are where the actual
action storage and discharge takes place. All
electrochemical cells consist of two electrodes separated by
some distance. The space between the electrodes is filled
with an electrolyte which is an ionic liquid that conducts
electricity. One electrode is the anode and it permits
electrons to flow out of it. The other electrode is the cathode
which receives the electrodes. The energy is stored in the
particular compounds that make up the anode, cathode and
the electrolyte such as zinc, copper, and SO4, respectively.
Series and parallel connections of batteries are the options to
increase the Ampere-Hour capacity or voltage and even both
in accordance to what is needed. Ampere-Hours are
normally used to indicate the amount of energy a storage
battery can deliver [5].
Battery will serve as the storage device of the design. It
will be the source of supply for the lighting loads. The
connections of the battery, parallel or series may be
considered to increase either the voltage of the Ampere-hour
capacity of the storage device.
2.5 Microcontrollers
A microcontroller is a single device which follows
instructions, reads information, stores information
communicates, measures time, and switches things on and
off. It also does other things, depending on the model. If you
are the type of person who likes to take thing apart you will
find microcontroller in all kinds of places. The most
common place is under the hood of almost any car produced
since 1985. Consumer items include televisions, compact
disc players, washing machines, telephones, and microwave
oven. Office computers use microcontroller in addition to
their man processor to control peripherals such as keyboards
and printers. Automated manufacturing systems use
microcontrollers in production equipment such as robots and
conveyor lines [6]. This study made use of microcontroller
to regulate the flow of voltage for battery storage.
2.6 Air Pressure Engine
Air pressure engines are engines in air pressure are
employed as motive force. From the extreme lightness and
mobility of air, it has been frequently proposed to employ it
as a medium for transmitting motion to machinery at a
considerable distance from the prime mover. Among the
first who attempted this is the celebrated Papin, who
invented the steel-yard safety-valve. He employed a fall of
water to compress the air in a cylinder, through the medium
of an intervening piston and he connected this cylinder to
another, at the mouth of a mine a mile distant, by means of a
pipe of that length. In the second cylinder was another
piston, the rod of which was intended to work a set of pump;
3
but, contrary to expectation, the compression of the air in
the first cylinder produced no movement in the piston of the
second. Papin subsequently attempted to bring his scheme
into use in England, but did not succeed. Afterwards,
however, he erected great machines in Auvergne and
Westphalia for draining mines, but so far from being
effective machines, they would not even begin to move. He
attributed the failure to the quantity of air in the pipe, which
must be condensed before it can condense the air in the
remote cylinder he therefore diminished the size of this pipe,
and made his water machine exhaust instead of condense,
and had no doubt that the immense velocity with which air
rushes into a void, would make a rapid and effectual
communication of power. But the machine stood still as
before. Near a century after this, an engineer at an ironfoundry in Wales erected a machine at a powerful fall of
water, which worked a set of cylinder bellows, the blowtype of which was conducted to the distance of a mile and a
half, where it was applied to a blast furnace; but
notwithstanding every care to make the conducting pipe
very air-tight, of great size, and as smooth as possible, it
would hardly blow out a candle. The failure was ascribed to
the impossibility of making the pipe air-tight, but above ten
minutes elapsed after the action of the piston in the bellows,
before the least wind could be perceived at the end of the
pipe, whereas the engineer calculated that the interval would
not exceed six seconds. The foregoing particulars are taken
from Dr. Robinson’s Natural Philosophy, art [8]. Air
pressure engines will be used to rotate the generator.
Concepts behind the air pressure engines and how it works
is important.
3.0 EXPERIMENTAL SECTION
3.1 Materials
In creating the system, the following materials were used
(refer to Figures 3 to 9) : Pneumatic Cylinder, check valve,
hose, air tank, pressure gauges, FRL, air motor, DC
generator, battery. According to Figure 2, for the whole
system, the materials were connected together to form the
seesaw.. Additional fittings were added for compatibility of
the materials connected. Some of the parts of the system
were brought second hand. The air tank was brought from a
shop of unused tank of compressor. The tank does not have
specification but, based on the measurement, the tank has a
volume of 4.5 gallons. Another material that was bought
second hand is the air motor; the motor was from unused car
buffing tool. The generator was bought second hand. There
are no available specifications, but it produces 12 V,
however, through testing, the specification were determined.
As this study went along, the design of the system was also
modified. One of the modifications is the removal of the
flywheel from the original design of the system. Though the
implementation of the flywheel proves to prolong the
22nd ASEMEP National Technical Symposium
rotation of the generator resulting to production of greater
amount of electricity, it was not added anymore due to time
constraint. This seesaw will be added to the solar panels as a
back-up
up for the charging system of the batteries. Referring
to Figure 10,, the actual installation of the project is located
at Hospicio de San Jose, Quiapo, Manila.
Figure 5. Air Pressure Tank
Figure 2. Proposed Layout of the Contraption
Figure 6. Air Pressure Gauge
Figure 3. Pneumatic Cylinder ( CKD Air Cylinder CMAZ –
30’ x 32” – CA-RE)
Figure 4. Pneumatic Check Valve
Figure 7. Left : Air Motor(25,000 rpm max), Right : DC
Generator(12 V, 0.8 A 750rpm)
4
22nd ASEMEP National Technical Symposium
3.2 Procedure
One of the determining factors in this study is the rate at
which children play. This is essential because the average
amount children play the seesaw will affect the charging
time and capacity of the battery. Number of children the
seesaw is exposed to may also be considered but that will
not be focused of the study. To be able to compute the time
a battery charges is dependent on how many cycles an
average play t the seesaw can be made in a given time.
Based from Tables 1, 2 and 3, it can be observed that from
10 to 600 psi, the higher the pressure the higher the time and
number of cycles it takes for the air pressure to increase by 5
psi. Also, if there are two pairs playing the seesaw, there are
minimal difference in the number of cycles compare to the
number of cycles if only one pair is playing. But there is a
significant difference in the number of hours the tank can be
filled. The researchers tested the number of cycles made
playing the seesaw in slow, average and fast play.
Figure 8. Car Battery(12 V, 40 A-h, Motolite)
Rate of Filling the Tank
Range(psi)
Cycles
Time(s)
1 pair
2 pairs
1 pair
2 pairs
0-5 psi
13
14
33
31
5-10 psi
8
9
11
20
10-15 psi
8
9
20
20
15-20 psi
10
8
25
17
20-25 psi
8
7
20
17
25-30 psi
12
11
28
22
30-35 psi
11
13
26
28
35-40 psi
13
12
31
24
40-45 psi
13
12
32
26
45-50 psi
13
17
32
34
50-55 psi
14
13
35
29
55-60 psi
16
10
37
20
Table 1. Rate of Filling the tank at 5-psi interval
Figure 9. Bearings and Fittings
Table 2. Computation of the number of cycles and rate of
filling the tank for 60 psi
Total Cycles
1 pair
139
2 pairs
135
Total Time(min)
1 pair
2 pairs
Figure 10. Actual Image of the Contraption
5
5.5
4.8
22nd ASEMEP National Technical Symposium
The number of cycles it takes to fill the tank
depends on the area of the cylinder. Also, the amount of air
that enters the tanks depends mainly on the volume of air
where the pneumatic cylinder travels. To prove the
researcher claimed that: due to testing, the fitted pressure of
air tank drives the air motor to produce 14.4 V to 15 is 60
psi.
constant. The pressure for this graph is at the tank side.
Figure 14 shows the characteristics of current and pressure.
As pressure rises, the current is held constant. The pressure
for this graph is plotted also at the tank side. Figure 15
shows that at regulated output pressure (14 psi), the
behaviour of voltage is constant. But the current shows an
erratic behaviour due to the sudden decrease in pressure.
Table 3. Computation of mass of air in tank
Tank Capacity Calculations
91.5785
0.08206
298
18.92706
4.08
60
25
5
tank size(US gal)
mass of 1 mol of air=29 gm
3.157879
mol
Figure 11. Testing of voltage produced by the generator.
5
50
0
0
10 Time (s) 20
30
Figure 12 Pressure vs. Time
PSI vs. Voltage
100
PSI
The number of cycles it takes to fill the tank depends on
the area of the cylinder. Also, the amount of air that enters
the tanks depends mainly on the volume of air where the
pneumatic cylinder travels. To prove the researcher claimed
that: due to testing, the fitted pressure of air tank drives the
air motor to produce 14.4 V to 15 is 60 psi. An excel
program was used to determine the number of cycles for the
tank to reach 60 psi. The result of 117 cycles is close to the
actual cycles of 139 cycles. Figure 11 shows the testing of
the voltage generated by the generator. Using this, the
number of cycles can also be expressed mathematically by
the given equation:
f =
PSI vs. Time
100
PSI
M(air)-gm
R
T(room)-K
V(air)-L
P(motor)-atm
P(motor)-psi
T(room)-C
V(air)-US gal
50
mKTroom
(equation 1)
Penv vq
0
Where:
f –number of cycles (frequency);
K-pressure constant;
Troom-room temperature;
Penv-atmospheric pressure (1atm);
V-volume per cycle;
q-cylinder capacity
14.35
14.4
14.45
14.5
Voltage(V)
14.55
14.6
0.7
0.8
Figure 13. PSI vs. Voltage
PSI vs. Current
100
PSI
4.0 RESULTS AND DISCUSSION
Figure 12 shows the relationship of pressure and time.
The group conducted six trials, starting with 80 psi up to 30
psi. The higher the pressure, the longer the time will it take
to drain the tank. Figure 13 shows the characteristics of
voltage and pressure. As pressure rises, the voltage is held
6
50
0
0.4
0.5
0.6
Current (A)
Figure 14. PSI vs. Current
22nd ASEMEP National Technical Symposium
2.
M. Smit “Abstract” Human-Powered Small-Scaled
Generation System for a Sustainable Dance Club, 2010 pp.
439
3.
McPherson and George, An introduction to Electrical
Machines and Transformers, John Wiley and Sons, 1990.
4.
S. R. Majumdar, “Pneumatic cylinders and air
motors” in Pneumatics System Principles and
Maintenance, McGraw-Hill, 1995
5.
A. Ter-Gazarian, Energy Storage for Power Systems,
Peter Peregrinus Ltd., 1994
6.
Peter Spasov, What is a microcontroller? And what is
it used for in Microcontroller Technology the 68HC11,
NJ: Prentice Hall, 1993.
Voltage (V)
Voltage vs. Current at each PSI
reading in tank
14.6
14.5
14.4
14.3
0.4
0.6
Current (A)
Figure 15. Voltage vs. Current
0.8
5.0 CONCLUSION
Based from the results the system, the seesaw
energy contrapment system generates small but significant
amount of electrical energy which can be stored to a battery
and can be used for lighting loads. The addition of the
seesaw in the solar panel is a good auxiliary source of power
and can be implemented to compensate the power
generation and the charging of the battery system. Further
development of the system is highly recommended in order
to increase the power generation efficiency. Pneumatics as
energy converters can also be applied in various playground
equipment such as seesaw, swing, and etc. Also, the charge
controller is essential in regulating the energy collected from
the system.
6.0 RECOMMENDATIONS
Long air tubes are also losses in air pressure
transmission leading to longer time to reach the prescribed
pressure. Increasing the number of seesaw with the
prescribed system can also improve the time for filling the
tank, increasing the time of the rotation of the air motor,
thus, longer time for the generator to produce power. If the
said recommendations are considered for the system, higher
power generation efficiency is expected.
7.0 ACKNOWLEDGMENT
The authors would like to thank Department of EECE,
Mapua Institute of Technology, Power Electronics
Laboratory, Kraft Philippines through Ace Saatchi and
Saatchi and the above creator for all of the blessings and
guidance.
8.0 REFERENCES
1.
S.R. Pandian, " Abstract," A Human Power Conversion
System Based on Children's Play, 2010 pp. 54
7
9.0 ABOUT THE AUTHORS
John Ray Abad, Merryl D. Capucao and Lynette Dane
C. Legaspi are all BS Electrical Engineering graduating
students of Mapua Institute of Technology. They took up
specialization courses on Power Systems Protection as part
of their undergraduate curricula. All of them are now
reviewing for the Registered Electrical Engineer (REE)
Board Examination this coming April.
Michael C. Pacis is a Registered
Electrical Engineer with a BS EE and
Master
of
Engineering-Electrical
Engineering (M.Eng’g-EE) Major in
Power Systems degree from MAPỦA
Institute of Technology. At present, he
is taking up his PhD EE (Power
Systems) at the University of the Philippines-Diliman. His
research interest includes Power System Protection,
Renewable Sources of Energy, Distributed Generation and
Smart Grids. He is the adviser of the authors in this project.
Jesus M. Martinez, Jr. is a graduate
of Mapua Institute of Technology,
Manila, Philippines, with a degree of
Bachelor of Science in Electrical
Engineering (1999) and Bachelor of
Science
in
Electronics
and
Communications Engineering (2000).
A Registered Electrical Engineer, he is a full-time faculty
member of the School of Electrical, Electronics and
Computer Engineering of the Mapua Institute of
Technology. His field of interest includes Power
Electronics, Control Systems and Signal Processing. He is
also the adviser of the authors in this project.
22nd ASEMEP National Technical Symposium
8