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Brake Intensity Advisory
System Final Design
Assessment
Jace Hall
Michael Purvis
Caleb Trotter
Edward Yri
ECE 4007-L01
12/05/2011
Project Details
• What
- BIAS (Brake Intensity Advisory System) operates by
illuminating an auxiliary set of LEDS located around
the perimeter of the standard brake lights when “hard
braking” occurs
• Cost
- The cost associated with mass production of the BIAS
is projected to be $66.83
2
Project Motivation
• Why
- The percentage of rear-end collisions (17% of all
claims) ranks second among all automobile accidents
• Who
- BIAS is intended for drivers and car manufacturers
who are concerned with operating and manufacturing
safer vehicles
3
Proposed vs. Actual Design Goals
Proposed Design Goal
Simple integration with current braking
systems
Non-intrusive design
Real-time response
Software definability based on vehicle
brake force parameters
4
Actual Design
Feature
Design Goal
Achieved
Design Goal
Achieved
Design Goal
Achieved
Design Goal
Achieved
Proposed vs. Actual Technical Objectives
Proposed Technical Objectives
5
Actual Technical
Performance
Receive a voltage sensor output between
0-3.3 V corresponding to a defined force.
Tech. Objective
Achieved
Categorize the inputs into three defined
states using the Mbed microcontroller.
Tech. Objective
Achieved
Illuminate the auxiliary LEDs when a
voltage of 1.9V or higher is received by the
microcontroller.
Tech. Objective
Achieved
Achieve a visual indication of braking force
in real time.
Tech. Objective
Achieved
High Level BIAS Schematic
6
Implemented BIAS Design
7
BIAS Operation
8
Testing the Force Sensing Resistor
Circuitry Output
Specification
•0 – 3.3 V output from the
force sensing resistor circuit
Testing Method
•The FSR was attached to the
vehicle brake pedal, and the
divider circuit resistor was
sized to produce the
appropriate output
9
Confirming Transition at the Hard Breaking
Voltage Threshold
Specification
• Real time response to the
determined voltage
threshold value
Testing Method
• A volt meter measured
the FSR voltage when
the second LED array
zone was initially
illuminated. The value
was 1.9 volts
10
Software Tests
Specifications
• Three defined controller
states corresponding to
illumination parameters
• Software definability
Testing Method
• LED output confirmed the
controller states operated
properly
• Sensitivity was altered to
ensure software definability
11
Design Modifications
• 12 V voltage regulator
added to reduce 13.8 V
car outlet voltage
• 1.5 MΩ grounding
resistor added to LED
driver circuit
• Common grounding
network established
12
Supporting Design Modification Figure
13
Problems Encountered and Solutions
• Problem: The LED driver
circuit current limiting
resistors were overloaded
• Solution: New resistors
were added with higher
power ratings
• Problem: LED brightness
was not consistent
• Solution: Shorted soldering
points were located, and
fixed
14
Prototype Cost Analysis
• Prototype Expenditures
- Of the requested $405, $128.97 was spent
- Many of the required parts were donated
• Mass Production Cost
- Reduced hardware cost based on quantities
purchased
- Lower microcontroller cost based on reduction of
features
15
Production Cost Break Down
Parts
Mass Production Cost
Prototype Cost
FSR
$16.00
$7.95
Wire/Connectors
$5.50
Donated
Resistors/Voltage
Regulator/Capacitors
$4.95
Donated
Perforated Boards
$5.75
Donated
Microcontroller
$2.16
Donated ($60)
LEDs
$19.25
$19.25
LED Drivers
$4.50
$4.50
Parts Total
$58.11
$31.70 ($91.70)
Contingency (15%)
$8.72
$4.76 ($13.76)
$66.83
$36.46 ($105.46)
TOTAL
16
Marketability and Projected Profits
– No automobile manufactures currently use a FSR to
process braking force and illuminate brake lights
accordingly
– Profits from the system would come from royalty
payments allotted to the patent holders
Projected BIAS Royalty Profits
Payment per Unit
Installed
Projected Installations
Total Profits
$2.00
500,000
$1,000,000
* Projected installations based on ~25% of the
vehicles produced by Ford Motor Company annually
17
Improvements and Future Work
• Create a printed circuit board for control and FSR
circuitry
• Integrate and program a lower cost microcontroller
• Fabricate lenses to cover LED arrays
• Test BIAS system on alternative vehicles
18