Download Mid-year presentation - Instrumented Football Helmet (Villanova)

Instrumented Football
Helmet
Louis Criso (ECE)
Francis Kitrick (ECE)
Ryan Lewis (ME)
Robert Sorbello (ECE)
Problem Statement
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Design a working football helmet that can
analyze the force of impact and determine if the
impact is dangerous to the player.
A microprocessor in the helmet will store data
regarding the impact for analysis that can be
later uploaded to a computer.
Motivation
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According to the National Football League,
there are 160 concussions sustained every year.
Roughly 17% of all high school football players
in the U.S. will suffer a concussion each year.
If left untreated, a concussion can be
detrimental to a players long-term health.
Approach
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Equip a standard football helmet with pressure
sensors and accelerometers to measure and store
the impact force sustained.
Build a testing apparatus to properly test and
calibrate our design to prepare it for game
situations.
The Schematic
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Processor
MMC
Accelerometers
Flex Sensors
Battery
Voltage Regulators
The Printed Circuit Board (PCB)
ARMexpress LITE Features
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32K Flash memory
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6 A/D channels, 10bit resolution, 100kHz
sample rate
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SPI support with 600 Kb transfer rate
Memory Map
A/D Channels
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6 A/D Channels
15 KHz sampling rate
6*15 KHz = 90K of data for one second
So we would need 9K of space to record hits for 100 ms (1/10th
of a second)
The A/D channels will be consistently buffered through the
flash memory until a certain threshold is reached.
Once this threshold is reached by any one of the sensors, then
the next 100 ms will recorded to the flash memory and written
to the memory card.
Programming Logic
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Overall software design of helmet includes:
Clock divider
 Obtaining inputs from sensors
 Determine intensity of recorded data
 Output accordingly
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First step: setting the sampling rate
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ARM processor runs at 60mhz. We want to scale
this down to 15khz.
First step in software is to create a delay
function/clock divider.
Using intervals obtained through clock divider,
store input from sensors into variables/memory.
Next: using the data
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Data from all sensors are stored in assigned
spots according to the type of sensor it was
obtained from. (accelerometer or pressure)
Values from sensors are compared against
calculated threshold values corresponding to
intensity of hit to the helmet.
The Output
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If the recorded hit is “safe” ie. below the
threshold value, value is discarded from memory.
If the hit is determined “un-safe” ie. Stronger
than allowable for the player’s safety then that
incident is recorded by saving the values of the
hit onto the card memory.
Finally alarm (led, buzzer) is triggered.
Apparatus Design
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Simple pendulum
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Use design specifications from
existing patent for football
helmet testing (US 6,871,525
B2).
2 m long arm with a 19 kg
impactor, generating 280 J of
energy.
With this information from
patent generated MathCAD
file to solve for initial angle (75
degrees)
Post Impact Analysis
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After the information from the sensors and
accelerometers is gathered, the data needs to be
analyzed to determine threshold.
The Gadd Severity Index (GSI):
t
GSI   a 2.5 dt
0
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Pass/fail basis: over 1,000 is a fail.
End Deliverables
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Plan on delivery a working football helmet that
can measure the force of impact, determine if
the impact was of danger to the player, and
store this data to be analyzed later.
A working testing apparatus to test future
football helmet designs.
Budget
Item
Budget
Accelerometer
$31.25
Wireless Adaptor
$70.00
PIC Microprocessor
$10.00
Li-Ion Battery and Manager
$10.00
Building Material
$30.00
Testing Material
$50.00
$201.25
Questions?
Comments?