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1.0 Introduction
The task was to develop a charger system for mobile devices that is powered by two
energy sources other than standard wall or vehicle power. Furthermore, the charging
system should be specific to the use case.
Electromotive Energy Capture
Based off the project objective and Harris’ connection to the military we identified
the use case of the United States Navy and the VHF radio. This project fits into
Harris’ RF Communication division, which is a leading supplier of secure radio
communications for the military. The communication sector of Harris’ business
resulted in $2,144 million in revenue out of their total revenue of $5.45 billion in
2012.The charging system of the VHF radio is critical for the US Navy because the
use of these radios are a Marine’s lifeline when lost at sea.
This solution came about through the use of the design process, which includes
recognizing the opportunity, defining the opportunity, creating specifications,
brainstorming ideas, evaluating ideas, analyzing, and testing of a prototype. In
addition, we recognized the opportunity for Harris in its RF Communications
Division by distributing a questionnaire to current Navy personal and veterans. The
design process ultimately created four prospective ideas, which were critiqued and
analyzed by the specifications in a screening process. In addition, a small-scale
experiment was conducted to discover the functionality of the prototypes before the
combination of the capture of electromotive power of ocean waves and a crank were
selected as the solution for the opportunity of a charging system for the Navy’s VHF
radios.
2.0 Project Background
The first solution uses technology that is based off Michael Faraday’s discovery that relative motion and magnetic field are related. Faraday’s Principle of Induction says that the faster the relative motion, the greater the
ε (electric and magnetic fields) generated across the conductor. The charging unit consists of a coil of copper wiring (solenoid), an earth magnet, and a capacitor. The kinetic motion of the waves moves the earth magnet
through the solenoid, which uses a circuit to convert the electromotive force of the motion into a DC voltage that is stored in a capacitor. The technology which is model off what is currently used in flashlights requires
30 to 60 seconds of shaking for up to three minutes of use before full discharge. The unit will be placed on the bowel of the ship in order to optimize the energy capture and will consist of multiple units enclosed in
waterproof container.
The United States Navy began to use Guglielmo Marconi’s invention of a
communication device that utilized electric oscillations at high frequencies, radios,
in 1905. In addition, by 1912 the Navy had radio transmitter communication devices
on all their major vessels. The radio is used for communication between others
vessels, harbors, bridges, and in rescue. VHF radios are especially critical in rescue
in that they will provide a GPS location for the rescue team. The VHF handheld
radio is convenient in that it is portable like a cellular phone; also this feature allows
them to be used on dinghies or small boats without electricity. In addition, current
handheld VHF radios have a maximum output of six watts. The typical handheld
radio consists of the following features: a waterproof exterior, buoyancy, access to
all Marine channels and NOAA weather channels, a GPS, an emergency strobe, a
flexible antennae, and a LED backlit screen. The typical unit runs on a rechargeable
lithium-ion battery set that lasts up to eight hours.
4.2 Research & Analysis
NiCd
NiMH
Lead-Acid
Li-Ion
Li-Ion
Polymer
Reusable
Alkaline
Fast Charge
Time
1 hour
2-4 hours
8-16 hours
2-4 hours
2-4 hours
2-3 hours
Overcharge
Tolerance
Moderate
Low
High
Very low
Low
Moderate
Cell Voltage
1.25V
1.25V
2V
3.6V
3.6V
1.5V
Load Current
1C
0.5C >
0.2C
1C >
1C >
0.2C >
Operating
Temperature
-40-60C
-20-60C
-20-60C
-20-60C
0-60C
0-65C
Maintenance
Requirement
30-60 days
60-90 days
3-6 months
Not required
Not required
Not required
Cost of Battery
$50 (7.2V)
$60 (7.2V)
$25 (6V)
$100 (7.2V)
$100 (7.2V)
$5 (9V)
Cost per Cycle
$0.04
$0.12
$0.10
$0.14
$0.29
$0.10-0.50
We chose the lithium ion rechargeable battery because it is high in energy density, it is lightweight, it
charges relatively fast, it stores more voltage than most rechargeable batteries, and there is no maintenance
required. The only downfall is that they could be costly.
In addition, to gathering technical background from research we decided to conduct a small scale
experiment order to gauge the practicality and the real world results of two plausible solutions. We tested
the electromotive ocean wave capture solution and the Limpet Model from the following procedure based
off the experiments of Dr. Jonathan Hare.
5.0 Detailed Design
The selected solution has a crankshaft integrated in the VHF radio, which will allow the user to
crank the shaft in order to create electricity from kinetic energy. Based off the size of the McMurdo
R5 GMDSS Handheld Radio, the crankshaft should be around 70 mm long and 20 mm wide with a
handle that is a cylinder with a diameter of 15 mm and height of 50 mm.
In order to create a design solution for a handheld VHF radio we targeted the
McMurdo R5 GMDSS Handheld Radio, which is a dependable and developed for
the harsh weathers at sea. It is built to meet IVO, GMDSS, and ETSI standards
while still being user-friendly.
The voltage is a result of movement across solenoid (V2 to V1). The diode (D) conducts current in the direction of the arrow, which prevents the conductor from discharging into the solenoid. The rectifier stores all the
positive pulses of the flashlight by flipping the negative pulses. The LED portion of the circuit shown in the figure will be replaced with a connector that uses the voltage to charge the dead batteries.
The next solution, which we considered for the alternative power source, was solar energy. The solar panels are made up of photovoltaic cells that are made up of two layers of silicon, semiconducting materials,
antireflective coating, and a metal backing. As the sunlight hits the semiconducting material, electrons are knocked loose. The antireflective coating ensures that the photons are absorbed and not reflected. Metal
conductor strips direct the flow of electrons and generate electricity. Traditional solar cells are made of flat-plate silicon and they are usually the most efficient at generating electricity. New technology has developed
“thin-film” cells made from amorphous silicon or non-silicon materials such as cadmium telluride. These solar cells are much smaller in size and flexible. This electricity would then be used to recharge the batteries for
use in the VHF radio.
In addition to a crankshaft integrated in the VHF radio, the selected solution also has a charging unit to
recharge the radio’s dead reusable batteries. The charging unit will consist of fifteen cylindrical tube
units which each contain copper wiring, an earth magnet, and a circuit board. The kinetic motion of the
waves moves the earth magnet through the solenoid, which uses a circuit to convert the electromotive
force of the motion into a DC voltage that is stored in a capacitor.
Each individual tube generates about one third of a Watt of energy due to the captured kinetic energy of
ocean waves. The power generated for each tube represents the energy dissipated in both the resistor and
the battery. The fifteen tubes will be organized in the same direction in a steel, waterproof box to allow
for the individual tube’s energy produced to be additive in the charging of the batteries to power a five
Watt VHF radio.
Another design solution that incorporated alternative energy is similar to the first solution in that it is based off Faraday’s Law of Induction but instead of using kinetic energy of ocean waves to move an
earth magnet through a copper wire, this solution uses a crank to generate the kinetic energy. Current hand crank radios can play music for up to an hour from 30 seconds of cranking. The crank could be
placed directly on the radio rather than encompassing one in a charging unit.
3.0 Project Objectives
The objective of this project is to use the design process to develop two alternative
energy sources to power the Navy’s VHF radios with regard to the consumers and
stakeholders needs.
A model of each individual tube in the box is pictured in detail above. The dimensions of the circuit
board are 25 mm by 50 mm, while the exterior tube has a height of 175 mm and a diameter of 50
mm, the copper tubing has a height of 75 mm and a diameter of 45 mm, and lastly the magnet has a
height of 50 mm and a diameter of 40 mm.
The relevant stakeholders we identified for the primary market of the United States
Navy were: the users, the retailer, the design team (engineers), the sales force, the
producers, and the shareholders. In addition, the potential secondary markets of the
product are commercial fisherman and cruise ship captains. Based off these relevant
stakeholders we constructed a questionnaire to identify necessary specifications for the
design of a solution.
In order to get a broad range of specifications we sent our questionnaire (see appendix)
to both active and retired Navy personal through the Pennsylvania State University
Alumni Directory. Based off the results of the survey we constructed specifications for
the design of the solution for our specific use case.
The final proposed solution was the Limpet Model, which utilizes the tidal power of ocean waves to change the air pressure in a chamber and produce electricity. The model is a chamber with only an opening at the
bottom so that water can freely enter. A passing wave changes the height of the water, which in turn compresses the air trapped within the chamber. The change in pressure of the air then causes a rubber sheet covering a
hole in the top of the chamber to moves in and out. Finally, a device called a piezoelectric transducer is attached to this rubber sheet that converts this movement into electricity.
After identifying and researching the opportunity prevented by Harris we developed a
list of specifications based off consumer needs. The specifications that our team
brainstormed based off a consumer questionnaire for the use case were: cost, weight,
size, ease of use, ruggedness, waterproof, efficiency, durability, ease of maintenance,
capacity, and reliability. We considered cost because of course we wanted to create the
ideal solution that would minimize cost. Our next consumer needs had to do with the
physical size of the solution because we did not want to create an obstacle for the
Navy’s officers. Also, we considered ease of use, ruggedness, and durability because the
officers should be able to depend on the solution to withstand and continually supply
power to the radios. Lastly, we consider needs such as capacity and efficiency to
determine the proper solution given the power required to operate the radio for an
extended period of time.
This solution of a combination of a fixed charging unit on the bowel of the ship and the integrate
crankshaft is practical because it adapts to the ever changing social, economic, technological, and
lifestyle trends. In terms of societal acceptance this solution emphases the importance of safety
specifically for the use case of the United States Navy by creating a dependable energy source that
always creates sufficient power. In addition, it follows the trends of adapting to technology as it is
created in this era of evolution. Lastly, it sells to a customer who is very brand loyal and aware by
adapting a currently well-recognized device in the market.
In addition to adapting to social factors, our solution meets the economic and environmental or
lifestyle needs of society. The price of the solution is extremely reasonable in that the most expensive
aspect of the design is the necessary copper wiring; however, the cost is cut due to the small diameter
of wiring required. This will allow the Navy to allocate limited funding to other important resources.
Another economic benefit of the solution is that the technology can be trademarked for the specific
use case and therefore increase sales revenue. This device also follows the every advancing trends of
technology by incorporates the diminishing size of rechargeable lithium ion batteries. Also in terms of
technology, since the solution has it’s own niche in the market place it has decreased competition
across the VHF radio market.
Lastly, this solution meets ideals of sustainability and ethics by minimizing waste, reusing materials,
and ultimately running solely on renewable energy. The solution reduces toxic waste by recharging
the reusable batteries of the radio rather than continually replacing the batteries with disposable ones.
Also, it reduces waste because since most of the material is coated to be waterproof it can be made of
recycled materials, which adds to the effort to become green. This solution encompasses all of the
factors affecting a market while still reducing its carbon footprint.
By: Yan Gao, Olivia Hoylman, Harsh Sultania, Emily Fliegel