This document is a final report from Team 13 describing their design of a Bicycle Deceleration Indicator. It includes sections on the problem statement and market research, product requirements, design approach, product testing, cost analysis, failure and hazard analysis, recommendations, and conclusions. The design harvests energy from the bicycle using a friction generator to power indicators that increase visibility and notify others when the cyclist is slowing down, improving safety with minimal maintenance requirements.

1. Bicycle Deceleration Indicator
Team 13
Final Report
May 3, 2016
Bryan Sellers
ECE BOX 300
Aidan Lippert
ECE BOX 179
Brian Mitchell
ECE BOX 218

2. Table of Contents
1
1.1
1.2
1.2.1
1.2.2
1.2.3
1.2.4
2
2.1
2.2
2.3
2.3.1
2.3.2
2.3.3
2.3.4
3
3.1
3.1.1
3.1.2
3.1.2.1
3.1.2.2
3.1.2.3
3.1.2.4
3.2
3.2.1
3.2.1.1
3.2.1.2
3.2.1.3
3.2.2
3.2.2.1
3.2.2.2
3.2.2.3
3.2.3
Introduction
Problem Statement
Market Research
Targeted Market
Research Methods
Research Results
Research Conclusions
Product Requirements
Customer Requirements
Product Specifications
Competitive Value Analysis
Essential Customer Criteria
Metrics for Value Analysis
Competitors
Value Analysis
Design Approach
System Architecture
Design Overview
Modular Overview
Power Generation
AC/DC Conversion
Digital Control
Indicator Output
Module Definition
Power Generation Module
Description of Functions
Module Input
Module Output
AC/DC Conversion Module
Description of Functions
Module Input
Module Output
Digital Control Module
5
5
5
5
5
6
7
8
8
8
9
9
12
13
20
22
22
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22
22
23
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24
24
24
24
25
25
27
27
29
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1

3. 3.2.3.1
3.2.3.2
3.2.3.3
3.2.4
3.2.4.1
3.2.4.2
3.2.4.3
3.2.5
3.2.5.1
3.2.5.2
3.2.5.3
3.2.5.4
3.2.2.5
3.2.5.6
4
4.1
4.2
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
5
5.1
5.2
6
6.1
6.2
7
8
Appendix A
Appendix B
Description of Functions
Module Input
Module Output
Indicator Output
Description of Functions
Module Input
Module Output
System Integration
Power Generation
AC/DC Conversion
Indicator Output
Digital Control
Full System Integration
System Testing
Product Testing
Product Functionality
System Testing and Results
Power Generation Module Testing
AC/DC Conversion Module Testing
Digital Control Module Testing
Indicator Output Module Testing
Integrated System Testing
Cost Analysis
Initial Investment
Return on Investment (ROI)
Failure and Hazard Analysis
Internal Threats
External Threats
Recommendations
Conclusions
Parts List
Computer Code
29
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30
30
30
31
31
31
32
32
32
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34
34
34
34
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36
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41
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43
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45
46
2

4. Table of Figures
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
Friction Generator Dynamo
Red LED
Generic Accelerometer Module
Rear Bike Light Bicycle Laser Beam Rear Tail Light
Rear Bike Light Specifications
Basecamp Rear Bike Light Remote Control
Rear Bike Light Specifications (2)
Front Bike Light 5­LED Black Bicycle Headlight
Front Bike Light Specifications
Front Bike Light, HeadLamp Kit
Front Bike Light Specifications (2)
Brakeless Deceleration Indicator
Top Level Diagram
Schematic of Dynamo
Speed vs. Output Power Graph
Schematic of the AC/DC Conversion Module
Schematic of Digital Control Module
Schematic of Indicator Output Module
AC/DC Conversion
AC/DC Conversion Multimeter Reading
Digital Control Module Testing
LED Output
Three­Module System Test
Three Module System on Single Breadboard
Mounted System on Bicycle
Bicycle Test Run
ROI Analysis
Digital Control Code
9
9
9
14
14
15
16
17
17
18
19
20
22
25
26
28
30
31
35
35
36
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38
38
39
40
41
48
3

5. Table of Tables
1.
2.
3.
4.
5.
6.
7.
8.
9.
Competitive Value Analysis
Power Generation
AC/DC Conversion
Digital Control
Indicator Output
Dynamo Specifications
Dynamo Temperature Test
Specifications of the Voltage Regulator
Parts List
20
22
23
23
24
26
27
28
45
4

6. 1. Introduction
1.1 ­ ​Problem Statement
The course design challenge was to conceive of, design, and develop a useful product with the
following parameters:
● Harvests stray energy from its environment
● Senses some parameter within that environment
● Provides some level of safety to the user
● Costs less than $50
The objective was to design a device that provides visibility for a bicycle and that automatically
notifies others nearby if the cyclist is slowing down. The purpose of the device is to improve the cyclist’s
safety and to prevent accidents.
1.2 ­ ​Market Research
Research was conducted to understand the needs of the product and the viability of the market.
Current products with similar components were consulted, reaffirming the desire for an improved product.
The conceived design exhibits promise to be successful in the current market.
1.2.1 ­ ​Targeted Market
The market for this product are people who use bicycles for daily transportation. According to the
U.S. Department of Transportation, an estimated 500,000 people are included in this targeted market. 1
1.2.2 ­ ​Research Methods
Several databases were utilized while conducting market research, each available through the
WPI Library. Google Scholar was our primary resource due to its accessible collection of patents. Current
products in the market with similar components to our design were identified. These similar products
were analyzed to improve the functionality of the chosen design, allowing us to improve upon their
shortcomings. Safety concerns with bicycle transportation were focused on, which reasserted the need for
the chosen product.
1.2.3 ­ ​Research Results
1
http://www.statisticbrain.com/commute­statistics/
5

7.
The market research explained the dangers of bicycle transportation, the reasons for most bicycle
accidents, and the main methods to prevent these accidents. Currently available products with similar
goals were evaluated, resulting in potential improvements for the chosen design.
The National High Traffic Safety Administration reported that most bicycle related injuries and
fatalities occur at night . These accidents can easily be avoided with bicycle safety indicators, notifying 2
other vehicles of the cyclist’s presence when visibility is limited.
There are currently bicycle lights available in the market, but they tend to be inadequate and
difficult to use . U.S. Federal law only requires bicycles to have a white front­facing light in “low 3
visibility conditions”, which does not help increase a cyclist’s visibility to others on the road. However, a
few states do also require rear­facing red lights. This required installation creates an opportunity for an
improved design.
It was found that “not seeing the bicycle” is claimed to be the leading cause of bicycle and car
collisions. This lack of visibility for the cyclist is clearly increasing his/her chance of injury or even death.
The highest­risk location for bicycle related accidents are intersections . These locations are 4
especially dangerous for cyclists because they are the most vulnerable. Cyclists often have to slow down
at intersections before turning. A way to notify others of the cyclist’s actions at these life­threatening
locations is clearly important.
Another leading cause of bicycle injury was due to vehicles rear­ending the bicycles because they
claimed to “not [know] they were slowing” or “not [see]” the cyclists . This restates the market need for a 5
product to display whether or not the cyclist is decelerating in order to prevent these accidents.
There are existing products in the market that have similar functions as the proposed design.
There are headlights and tail lights that operate using batteries that require replacement and do not have
energy­generating components. There is also a patent for a product that uses an accelerometer to detect if
the bicycle is slowing down, but it also does not rely on energy­generating components.
1.2.4 ­ ​Research Conclusions
2
"Traffic Safety Facts." ​Http://www­nrd.nhtsa.dot.gov​. Apr. 2014. Web.
3
Larson, C. (2011, March 21). Survey Result: Bike Light Use Good, But Not Good Enough. Retrieved
March 19, 2016, from https://btaoregon.org/2011/03/survey­result­bike­light­use­good­but­not­good­enough/
4
​Isaksson­Hellman, I., & Werneke, J. (2016). Detailed description of bicycle and passenger car collisions
based on insurance claims. ​Safety Science​.
5
​Williams, T. (2015). ​Investigating characteristics in a spatial context that contribute to where bicycle
accidents occur​ (Doctoral dissertation, Lincoln University).
6

8. Research has proven that bicycle related accidents are clearly a problem. These accidents are
largely caused by cyclist visibility issues or confusion about a cyclist’s movements. Therefore, bicycle
safety can be improved by providing a product that improves the bicycle’s visibility at night and notifies
vehicles when it is slowing down. There is a viable market and need for a useful product that combines
active lights, an indicator showing deceleration, and a self­powering generator.
7

9. 2. Product Requirements
2.1 ­ ​Customer Requirements
Using the extensive market research, a list of specific customer requirements was created. The
research and the safety issues that need to be addressed provide insight to the product specifications that
would apply to the market. These explicit requirements are listed below:
­ Indicate when the bicycle is slowing down
­ Run automatically
­ Increase visibility of bicycle
­ Durable (long life­span)
Along with the above requirements, several implicit requirements are also considered and shown below:
­ Low­maintenance
­ Meets federal standards for vehicle lighting (red/yellow/orange for rear lighting)
­ Affordable (comparable to bicycle accessories)
­ Easy installation
2.2 ­ ​Product Specifications
The following specifications were determined based on the requirements for the product:
­ Friction Generator­ Runs automatically and low user maintenance
­ High­Intensity Red LED­ Easily visible display to other drivers
­ Accelerometer­ Senses when the bicycle is decelerating
­ Microcontroller­ Commands LED to light up automatically
­ Durable Casing­ Increases life span of the device
Friction Generator (Dynamo) ­ The product will use a reliable friction generator to avoid the dependency
on batteries. A friction generator was determined to be the optimal energy generator because it will
constantly produce electricity while the bicycle is in motion. A solar cell was also considered, however it
was determined that batteries would be required for night­cycling, and storing the bicycle in a garage
would not charge the batteries. By simply relying on a dynamo for energy, the bicycle could be used
normally and the device would be automatic without need for turning on or off.
8

10.
Figure 1: Friction Generator Dynamo. 6
High­Intensity Red LED ­ The product will use a high­intensity red LED to indicate when the bicycle is
slowing down. Red was chosen in part due to its high visibility in all conditions. The other reason for
choosing a red LED is the relatively low cutoff voltage requirement to illuminate the bulb.
Figure 2: Red LED. 7
Accelerometer ­ An accelerometer was chosen as the deceleration sensor due to its ability to detect small
changes in acceleration. For the product, the accelerometer will provide raw input data to be filtered and
used to determine when the bicycle is slowing down.
Figure 3: Generic Accelerometer Module. 8
Microcontroller ­ A microcontroller will be used on the device to analyze the raw input data from the
accelerometer and to power the output LED when the bicycle is determined to be decelerating. A
microcontroller is preferred over a microprocessor because all the components can be integrated into a
6
http://ecx.images­amazon.com/images/I/31ypwTcotdL.jpg
7
http://uk.farnell.com/productimages/standard/en_GB/42251794.jpg
8
http://learn.parallax.com/sites/default/files/content/kickstart/images/Memsic2125­2.png
9

11. single chip. The processing for this device will not be very computationally intensive and
microcontrollers tend to require less energy to fully operate.
Durable Casing ­ The product will utilize a durable casing to contain and protect the accelerometer,
microcontroller, and LED. The casing must be able to withstand conditions such as rain and normal use
without failing. The friction generator will be a self­contained device connected by water­resistant wires.
2.3 ­ ​Competitive Value Analysis
2.3.1 ­ ​Essential Customer Criteria
Quality:
Operating Conditions: How well will the product perform when it is exposed to weather or harsh
conditions.
Value Value Point
Well (sustains little to no damage) 3
Moderate (sustains minor damage, but still functions) 2
Poor (sustains significant damage, but still functions) 1
Not at all (doesn’t function after receiving damage) 0
Display: The visibility of the display.
Value Value Point
Very Well (very bright and visible) 4
Well (bright and visible) 3
Moderate (mildly bright and barely visible) 2
Poor (very difficult to see) 1
Not at all (no light displayed) 0
Responsiveness of Sensor: How well the sensor will react to acceleration/deceleration.
10

12.
Value Value Point
Well (senses any change in velocity) 3
Moderate (senses moderate change in velocity) 2
Poor (only senses major change in velocity) 1
Not at all (doesn’t sense change in velocity) 0
Convenience:
User Input: How fast does the user have to pedal for sensor/LED operation.
Value Value Point
Well (minimal user input for full functionality) 3
Moderate (moderate user input for full functionality) 2
Poor (considerate user input for full functionality) 1
Not at all (no functionality from significant user input) 0
Installation Versatility: Can easily install on all bicycles.
Value Value Point
Well (universal will all bicycles) 3
Moderate (requires minor modifications to install) 2
Poor (requires significant modifications to install) 1
Not at all (can not be installed on bicycles) 0
Battery Maintenance: How often does the battery need to be replaced.
11

13.
Value Value Point
Never (energy generation) 5
Never (energy supply) 4
Infrequently (rechargeable battery) 3
Infrequently (replaceable battery) 2
Often (short lifespan of battery) 1
Cost:
Price: Consumer’s cost for the product.
Value Value Point
<$30 4
$30 ­ $40 3
$40 ­ $50 2
$50 ­ $60 1
$50< 0
2.3.2 ­ ​Metrics for Value Analysis
The value of the competitor criteria is weighted below:
● Operating Conditions (2)
● Display (3)
● Responsiveness of Sensor (3)
● User Input (2)
● Installation Versatility (2)
● Battery Maintenance (2)
● Price (1)
12

14. Each given criterion needed to be weighted depending on its significance to the customer. The
most essential criterion is the responsiveness of the sensor. If the device can not properly measure the
acceleration of the bicycle, the cyclist’s safety is at risk. The visibility of the display is also crucial
towards the functionality of the device. Other vehicles and cyclists need to be able to easily see the LED
when the bicycle is slowing down for the device to be effective. The chosen rating for display is a 3.
Durability is very important and is rated a 3. The lifespan of the device is important, and for it to last, it
needs to be able to withstand harsh conditions. The user input is important because the user should not
have to be moving especially quickly for the device to still function. This value was rated a 2. The battery
maintenance is influential because the customer does not have to worry about replacing the battery for the
product to continue to function. This value was rated a 2. Installation versatility was next due to its
importance for the convenience of the customer. It is not as crucial because installation is a one­time
process and it does not affect the functionality of the device. It was rated a 2. Price was rated last as a 1.
The device can be more expensive because it offers a premium solution that cyclists need to improve their
safety on the streets.
2.3.3 ­ ​Competitors
Market research has shown that there are a variety of current products that offer similar functions
to our design. There are many tail lights for the sole purpose of notifying other vehicles of the cyclist’s
presence. There are headlights to improve the cyclist’s frontal vision. Lastly, there is a similar product
that senses the bicycle’s deceleration. These products can be compared in similar markets because they all
improve the safety of the cyclist. The chosen design is unique from its predecessors due to its
consolidation of features and energy generation component.
Tail Lights:
Tail lights are lights that attach to the rear of the bicycle and light up to improve visibility
of the bicycle to others nearby. These lights typically have one function and operate constantly.
Some lights are constantly illuminated, and some constantly flash on and off. They all rely on
batteries for operation, which need to be replaced or recharged.
These products vary in price from about $10 to about $50 depending on the features that
they offer. The distance that the light can be seen from has a large impact on the price of the
product. Extra features like turn signals, or having a rechargeable battery are also influential on
the final price of the product. Illustrated below are two top products on both ends of the pricing
spectrum:
13

15. 9
Figure 4: ​Rear Bike Light Bicycle Laser Beam Rear Tail Light
This product is listed at $9.99. This product offers the basic features that a tail light demands,
including a flashing light option and a high visibility light. It requires replaceable batteries that are not
included.
Figure 5: Rear Bike Light Specifications
9
http://tinyurl.com/h65poyv
14

16. 10
Figure 6: ​Basecamp Rear Bike Light Remote Control / Smart / Wireless Bicycle Remote Laser Tail Light
BC­421 Black
This product is listed at $39.99. This product offers a wide variety of features, ranging from turn
signals to a USB charging point for rechargeability. The LED is also very powerful, shooting light a far
distance. Due to the extensiveness of the components, the list of product specifications is also more
extensive.
10
http://tinyurl.com/jkcuhhq
15

17.
Figure 7: Rear Bike Light Specifications (2)
Headlights:
Headlights are designed to shine a bright light in front of the bicycle to improve the
cyclists frontal vision. They typically shine a constant light forwards, illuminating a certain
distance in front of the bicycle. These products are typically consistent in the features that they
offer, and are about the same price. Similar to tail lights, headlights also rely on batteries for
operation.
Headlights usually cost about $10 ­ $20 with a few premium options around $40. The
illumination strength of the lights are the largest contributing factor towards an increase in market
price. Two popular options are depicted below:
16

18. 11
Figure 8: ​Front Bike Light 5­LED Black Bicycle Headlight with Batteries Set
This product offers the bare minimum features for a headlight. It is listed at only $6.99. It has the sole
purpose of shining a light forwards to improve the cyclist’s vision. The specifications are shown below:
Figure 9: Front Bike Light Specifications
11
http://tinyurl.com/hn7pfmx
17

19. 12
Figure 10: Front Bike Light,LS097 8400Lm 5 Mode 6 x CREE XM­L T6 LED Bike Bicycle HeadLight
HeadLamp Kit
This product also has very simplistic features, but it displays a very powerful light. It a premium
product, so it is listed at $47.49. It is targeted at high­level cyclists who demand the highest­quality
product on the market.
12
http://tinyurl.com/j33k52p
18

20. Figure 11: Front Bike Light Specifications (2)
Brakeless Deceleration Indicator:
There is one prominent product on the market with this specialization. This product uses
an accelerometer to detect if the motorcyclist is braking, and indicate others nearby via a flashing
light. This product is very similar to the chosen design in the features that it offers, but it operates
slightly differently and is targeting a different market. This product also relies on batteries instead
of energy generation. This product is displayed below:
19

21. 13
Figure 12: Brakeless Deceleration Indicator
This product is listed at $129.95, demonstrating its superiority to the previously mentioned
products in the bicycle safety market.
2.3.4 ­ ​Value Analysis
Table 1. Competitive Value Analysis
The value analysis demonstrates that the chosen design is the most valuable product compared to
the market competitors based on the chosen criteria. Comparing market competitors was beneficial in
order to properly understand features that customer’s demand in the market, and how well companies
deliver those features in their products. The brakeless deceleration indicator (44) is easily the top
13
http://vololights.com/products/vololights­enhanced­motorcycle­visibility/#shopify­product­reviews
20

22. competitor for the chosen design (46) due to its similar functionalities and features that it offers.
However, the chosen design’s energy generating components give it the slight edge in the market.
Any sensitivities in the value analysis likely stem from the chosen criteria and the interpreted
weighting values. The customer’s needs were predicted without certainty because the chosen design has
yet to be introduced to the market.
21

23. 3. Design Approach
3.1 ­ ​System Architecture
3.1.1 ­ ​Design Overview
Figure 13: Top Level Diagram
3.1.2 ­ ​Modular Overview
3.1.2.1 ­​ Power Generation
Power needs to be supplied to meet the energy needs of the various components. The
energy from the rotation of the wheels of the bicycle can be harnessed to power the system.
22

24.
Implementation Mountable dynamo generator
Input Wheel rotation
Output Average 3W at 6V (AC). Depends on speed of bicycle
Table 2: Power Generation
A reliable friction generator supplies AC power to the entire system and removes the
dependency on batteries. The dynamo constantly and autonomously produces energy while the
bicycle is in motion.
3.1.2.2 ­ ​AC/DC Conversion
The power produced by the dynamo is output in AC, but DC power at the proper voltage
is required to power the microcontroller. The AC to DC converter converts the generated power
into a usable form.
Implementation Bridge Rectifier, Smoothing Capacitor, Voltage Regulator
Input Average 3W at 6V (AC)
Output 3.3V (DC), maximum 800mA
Table 3: AC/DC Conversion
A bridge rectifier, smoothing capacitor, and a voltage regulator are all essential
components to convert to and maintain the desired voltage.
3.1.2.3 ­ ​Digital Control
The converted DC power is used to operate the control system for the design. The logic
system senses change in acceleration and provides commands for the device’s output. This
module is required for the device to accurately perform its main purpose which is to indicate
when the bicycle is decelerating.
Implementation Microcontroller and Accelerometer
Input 3.3V DC
Output 3V DC
Table 4: Digital Control
23

25. The accelerometer will detect changes in velocity of the bicycle and notify the
microcontroller. The programmed microcontroller can then send commands to the indicator
output.
3.1.2.4 ­ ​Indicator Output
The indicator output will notify others nearby of the cyclist’s deceleration. The bright
display is prominent and easily visible, ensuring the effectiveness of the device.
Implementation Bright Red LED Array
Input Max: V​in​=2.4V, i​in​=100mA
Output LEDs light up or flash depending on microcontroller commands
Table 5: Indicator Output
The LED array will receive power and light up accordingly based on the commands from
the microcontroller. A transistor will receive the signal from the microcontroller and operate as a
switch. A resistor will be used to drop the voltage down to below the maximum operating
voltage.
3.2 ­ ​Module Definition
3.2.1 ­​ Power Generation Module
3.2.1.1 ­ ​Description of Functions
This module will generate AC power by harnessing energy from the bicycle wheel
rotation. The fundamental component for this module is a bicycle dynamo. A dynamo is an
electrostatic friction generator. It operates by using manual power (bicycle pedaling) to generate
charge. The dynamo provides a constant supply of clean energy, adding a factor of convenience
for the user.
24

26. The following schematic illustrates the dynamo’s functional components:
14
Figure 14: Schematic of Dynamo
3.2.1.2 ­ ​Module Input
The only input required for this module is from the user. The user manually pedals the
bicycle, which causes the bicycle wheels to rotate. The wheel rotation energy is then harnessed by
this module.
3.2.1.3 ­ ​Module Output
AC power will be output to the entire system when the cyclist is moving. The AC output
parameters will vary, depending on the user’s velocity. These technical parameters can be found
below:
14
http://www.seeedstudio.com/wiki/Bicycle_Dynamo_With_Bracket_­_6V_3W
25

27. Constant­Resistance Load Testing （18 ohms）
Speed（km/h） 15
Output Power (W) Output Voltage (V) Output Current (A)
5 0.45 2.45 0.115
15 1.89 5.78 0.325
30 3.21 7.23 0.435
Table 6: Dynamo Specifications
Table 6 demonstrates that as the speed of the bicycle increases, the output power, voltage,
and current increase. The following graph displays the relationship between the cyclist’s speed
and the power output from the dynamo.
Figure 15: Speed vs. Output Power Graph
Figure 15 illustrates that the output power increases at approximately an exponential rate
as the cyclist’s speed increases. The exponential dotted trendline closely follows the speed vs.
output power curve, which further supports this claim.
As the dynamo produces electrical energy, heat energy is produced as well. The heat
output should be considered when testing. The following table exhibits possible temperatures of
the dynamo during operation:
15
http://www.seeedstudio.com/wiki/Bicycle_Dynamo_With_Bracket_­_6V_3W
26

28. Temperature Test:
Surroundings temp. Shell temp. Temp. rise
20℃ 16
55.2℃ 32.2℃
Table 7: Dynamo Temperature Test
The dynamo supplies more than enough power to meet the demand of the rest system
even when the cyclist is moving at a slow pace. At optimal performance, the dynamo will output
3W at 6V. However, if the cyclist is moving quickly, the output voltage is excessive, and needs
to be regulated. This regulation will be discussed later in the report.
The output is also supplied in AC, which needs to be converted to DC to be used by the
other components.This conversion process will be examined in the next module.
3.2.2 ­ ​AC/DC Conversion Module
3.2.2.1 ­ ​Description of Functions
The AC/DC Conversion module will take the power from the dynamo generator and
convert it to a form that can be used to power the other modules. Three components are used in
this module. The first component is the converter. It consists of 4 diodes arranged to form a
bridge rectifier, converting the input alternating current (AC) to direct current (DC). The
converted DC power is often pulsed as a wave, which can lead to resistive losses. However, to
minimize these losses, a 1000μF capacitor is then used to smooth the wave and provide a low
impedance path for the output. Lastly, a 3.3V linear regulator is included in the process to
normalize the voltage to 3.3V, reaching the desired voltage for the remaining components.
A schematic was created to illustrate the AC to DC conversion process and the
integration between each of the components. This schematic is depicted below:
16
http://www.seeedstudio.com/wiki/Bicycle_Dynamo_With_Bracket_­_6V_3W
27

29.
Figure 16: Schematic of the AC/DC Conversion Module.
The bridge rectifier is composed of 4 diodes. It splits the components of the AC sine
wave and recombines them as a full wave rectification. The capacitor is added between the line
voltage and the ground voltage to minimize the voltage ripple. The regulator takes in the line
voltage and the common ground and outputs a regulated voltage of 3.3V by automatically varying
the internal resistance.
The technical specifications for the voltage regulator can be found below in the following
table:
17
Table 8: Specifications of the Voltage Regulator.
17
https://www.sparkfun.com/datasheets/Components/LD1117V33.pdf
28

30. 3.2.2.2 ­ ​Module Input
The input to the AC/DC Conversion module is the AC output of the dynamo. This input
will be variable and heavily influenced by the speed of motion of the bicycle. The ranges are
documented above in Table 6. The maximum input voltage the system can handle was determined
to be 15V, which far exceeds the potential output achievable by the dynamo generator with an
average cyclist powering the device. Under normal operating conditions, the dynamo is expected
to produce between 2­8V, which is supported by the proposed conversion module.
3.2.2.3 ­ ​Module Output
After the completion of the conversion process, this module will output a constant 3.3V.
The output current will vary depending on the speed of the bicycle, peaking at 800mA. The
output voltage is only predicted to drop lower than 3.3V if the bicycle is moving at speeds around
or lower than 5 km/h, which is impractically slow for cycling. If the input voltage is lower than
1.1V, the output will drop to 0V. If the dynamo is operating at optimum levels, the AC/DC
Conversion module will output 3.3V and up to 800mA. The modified output will be utilized to
power the rest of the system.
3.2.3 ­ ​Digital Control Module
3.2.3.1 ­ ​Descriptions of Functions
The purpose of the Digital Control module is to read in the acceleration of the bicycle
using the MMA8451 accelerometer and to determine when to activate the Indication Output
module using digital logic in the MSP430G2553 microcontroller. When a 3.3V input is provided
to power the control module, the accelerometer will begin to record the acceleration of the bicycle
and provide the data to the microcontroller. If there is any backwards acceleration sensed by the
accelerometer, the microcontroller will execute code that will direct the output module to activate
and light the LED array. When needed, the microcontroller will output 3V DC to the LED array.
The schematic below illustrates the pins that connect the microcontroller, accelerometer, and
LED array, and how they are integrated with each other.
29

31.
Figure 17: Schematic of Digital Control Module
3.2.3.2 ­ ​Module Input
The microcontroller and the accelerometer will share an input voltage (V​CC​) of 3.3V DC.
The 3.3V is expected to be a constant value as it is coming from the output of the voltage
regulator, and may only drop in voltage if the bicycle is traveling at extremely slow speeds of less
than 5 km/h. The typical current supply to the control module is 330 μA, offering a power draw
of only 1.1 mW.
While the program is running, the microcontroller will be expecting 8 bit char data values
from the accelerometer at a rate of 1 sample/ms. The accelerometer uses its own built­in analog to
digital converter, and therefore the values from the accelerometer can be immediately read by the
microcontroller. A sample rate of 1 sample/ms should be sufficient to sense any deceleration and
to resultantly light up the LED array.
3.2.3.3 ­ ​Module Output
The output of the digital control module will be an active high voltage of 3V to the LED
array when the accelerometer detects a backwards acceleration. The data rate of the output will be
the same as the sample rate of the accelerometer, which is 1 sample/ms. The code implemented in
the microcontroller will entirely control the output of the module.
3.2.4 ­ ​Indicator Output Module
3.2.4.1 ­ ​Description of Functions
The purpose of the Indicator Output module is to produce a noticeable visual display
when a signal is received from the digital control module. When a signal is received to the NPN
transistor, the supply voltage V​in​ will flow through and into the resistor. Given that V​in​ is 3.3V,
and the absolute maximum characteristics for the LEDs are 2.4V with 20mA, the resistor R1 will
30

32. have a value of at least 9Ω to avoid exceeding the absolute maximum voltage. The value of R1
will be tested along with the LED array, starting at a value of at least 10Ω.
The schematic for the LED Output Array is depicted below:
Figure 18: Schematic of Indicator Output Module
3.2.4.2 ­ ​Module Inputs
The inputs to the Indicator Output module are the common ground, the positive voltage
rail, V​cc​/V​in ​, and the signal in from the logic system. The common ground is assumed to be 0V.
The positive voltage rail will be 3.3V at optimal operating conditions. This value may decrease
slightly when the bicycle is moving at a very low velocity. The signal from the microcontroller
will be V​cc​­0.3V for all values of V​cc​. This module will draw 100mA from the V​cc​ and will
dissipate .33W of energy.
3.2.4.3 ­ ​Module Outputs
The output of the Indicator Output module is a red light emitted by the 5 high­intensity
red LEDs. The output will be activated by a signal from the logic system. The .33W will be
dissipated.
3.2.5 ­ ​System Integration
Each module will be tested individually to ensure that each module functions properly separately
before integrating them together into the entire system. The hardware modules that must be tested are the
31

33. Power Generation module and the AC/DC module. The software of the Digital Control and Output
module must also be programmed and tested before they are integrated with their hardware counterparts.
3.2.5.1 ­ ​Power Generation
The dynamo generator will be attached to a bicycle wheel and have its output AC
voltages monitored at various speeds on the bicycle. The dynamo must be able to output 6V and
1.89W at an average speed of 15 km/h. The generator’s voltage output should only drop below an
operational level of 3.3V when the bicycle is traveling at a much slower speed of 5 km/h. These
values will ensure that when the generator is connected to the AC/DC converter, and the system
as a whole, it will provide enough power to operate the microcontroller, and output to the LED.
3.2.5.2 ­ ​AC/DC Conversion
Once the AC/DC conversion module circuit is constructed, the module will be connected
to an AC voltage source and a load resistance of 50Ω. The AC voltage input will be varied and
tested between the minimum value of 3.3V and the maximum value of 8V. The output voltage of
the regulator is expected to be 3.3V at all values of input voltage, showing how it will perform
when connected to the dynamo input generator.
3.2.5.3 ­ ​Indicator Output
The LED array will be tested by itself before it is integrated with the microcontroller. The
LEDs are expected to receive an input of 2.4V from the microcontroller pin. The actual output
voltage of the microcontroller is expected to be 3V, so it will be regulated down to 2.4V using a
resistor with at least 10Ω (as calculated in section 3.4). To test the LED array configuration
independently, the module will be connected to a 3.3V power source to see if the LEDs light up.
3.2.5.4 ­ ​Digital Control
To test the Digital Control module, the MMA8451 accelerometer will be connected to the
MSP430G2553 microcontroller via pins 1.6 and 1.7. Both the microcontroller and the
accelerometer will be powered by a 3.3V DC voltage for use in testing. The output LED array
will also be connected to the microcontroller via pin 1.2. Code will be written in Code Composer
Studio that will read the data input from the accelerometer, notice when there is a prolonged
negative acceleration, and trigger the illumination of the output LEDs. This module will be
initially tested by using variables in the code to simulate negative acceleration. When the code is
complete and operational, the full module will be tested by connecting it to a 3.3V power source,
and actually simulating a negative voltage with motion of the module in order to light the LEDs.
3.2.5.5 ­ ​Full System Integration
After successful testing of every individual module, the full system will be prototyped
following the circuit diagrams that have been shown earlier in the report. The dynamo generator
will be directly attached to the front wheel of the bicycle. The rest of the components will be
wired together on a protoboard for initial testing. The board will be attached to the back of the
bicycle and oriented in the correct direction in order to detect backwards motion. The final device
32

34. will be enclosed in durable casing and wiring, and the modules will be soldered together to create
a more permanent product.
3.2.5.6 ­ ​System Testing
Once all the modules have been integrated together, and the prototype is mounted on the
bicycle, the system will be tested by riding the bicycle at varying speeds to observe the effect on
the LED. If every module is working together correctly, then the LED should function when
decelerating from all speeds over 5 km/h. If something is not working as expected, then each
module will be reanalyzed individually to detect issue and develop a solution.
33

35. 4. Product Testing
4.1 ­ ​Product Functionality
The product is 100% functional, fulfilling all tested criteria. Each of the product’s
features are functional. The product successfully harnessed energy from the rotation of the tires,
sensed deceleration of the bicycle, and provided the desired LED output. The input ranges of
each module properly met the predicted specifications. The output devices for each module also
performed fully functionally, also meeting the predicted specifications. Lastly, the power
requirements, provided by the dynamo, comfortably met the specifications demanded by the
system in order to function optimally.
4.2 ­ ​System Testing & Results
The system testing was broken down by module to ensure proper functionality before integration.
After each module was tested and performed as expected, the product could be assembled and tested as
one unit.
4.2.1 ­ ​Power Generation Module Testing
The power generation module has performed as expected thus far through testing. The dynamo
was tested by manually spinning the generator by hand at a constant rate. The AC output was recorded in
the lab with an oscilloscope at a constant frequency, and at about 6V, exactly as anticipated. The lab
testing was a success, and the module was ready to be integrated with the other modules on the bicycle.
4.2.2 ­ ​AC/DC Conversion Module Testing
The AC/DC conversion module has also performed as expected through testing. The components
were mounted on a breadboard according to the designed schematic and were tested in the lab. A picture
of module is depicted below:
34

36.
Figure 19: AC/DC Conversion
A function generator was used to input 6V AC into the module, and the output was measured
constantly at about 3.3V DC. The multimeter reading is shown below:
Figure 20: AC/DC Conversion Multimeter Reading
The AC/DC conversion module was able to convert the input AC voltage into the desired DC
output, demonstrating the effectiveness of the module.
35

37.
4.2.3 ­ ​Digital Control Module Testing
The digital control module has performed as expected throughout the testing phase. The
preliminary code commands the onboard LED to light up when desired. However, the most difficult
aspect of this module has been integrating the accelerometer with the microcontroller using the I​2​
C data
transfer protocol. Once the two components were successfully integrated, however, the coding was
straightforward.
The module was mounted on a breadboard, and connected to a power supply as the input. When
the module is at rest, the accelerometer does not detect any acceleration in the specified Y­direction, and
the onboard LED is constantly lit. When the module is tilted in the correct direction, the accelerometer
detects the downward acceleration due to gravity on the its Y­axis, and the onboard LED flashes at a
constant rate. This module is displayed below:
Figure 21: Digital Control Module Testing
The illuminated onboard LED portrays that the system is at rest. These results occurred exactly as
anticipated, demonstrating the success of the module. The module can be used to combine the AC/DC
conversion module and indicator output module.
4.2.4 ­ ​Indicator Output Module Testing
The indicator output module has performed even better than predicted. On a breadboard, the
LEDs were mounted in parallel with one another, and with a resistor in series. A 100Ω resistor was
initially used as a precaution to avoid overloading the LEDs, and to protect the eye’s of the testers. 3.3V
was supplied from a DC power supply as the module’s input, causing the LEDs to faintly light up.
However, the success of the design demands a very bright and noticeable output. The resistor in series
36

38. was modified, and replaced with a 10Ω resistor. The observed LED output was as bright as desired. This
module in effect can be seen below:
Figure 22: LED Output
The minor resistor adjustment permitted the LED output to fulfill the product requirement. This
module has performed optimally in the lab and has proven to be effective on its own.
4.2.5 ­ ​Integrated System Testing
After each module was working individually, they were integrated together for testing. The
AC/DC conversion module was integrated with the indicator output module by connecting the circuits.
The joint module was tested with a power supply, and the result was successful. Next, the digital control
module was connected to the joint module, creating a three­module system. This system was connected to
a power supply for testing. The LEDs output a constant bright light when the system is at rest. However,
when the accelerometer is moved, the output LEDs flash. The module is shown below:
37

39.
Figure 23: Three­Module System Test
This three­module system tested successfully, and it was time to integrate it with the power
generation module on the bicycle. However, before mounting the three­module system onto the bicycle, it
needed to be installed onto one breadboard for portability and convenience. This three module system is
shown functioning below:
Figure 24: Three Module System on Single Breadboard
38

40. This single breadboard system worked properly, and was ready to mount onto the bicycle. In
order to mount the system, casing was needed to protect and secure the components while the bicycle is in
motion. The breadboard and microcontroller were attached to durable cardboard with duct tape,
stabilizing the system. Next, the unit was attached to the rear of the bicycle below the seat, so that the
indicator lights could be clearly visible to others behind the bicycle. Finally, the power generation
module(the dynamo) was fastened to the rear tire with metal brackets and bolts, and then connected to the
breadboard system with a wire. The entire system was now installed on the bicycle and ready for testing.
The mounted system on the bicycle can be seen below:
Figure 25: Mounted System on Bicycle
The product was initially tested by manually spinning the wheel to determine if the dynamo
output was performing as planned. The friction from the tire caused the friction generator to rotate, which
in turn caused the LEDs to light up brightly. The bicycle was then brought outside for further testing in a
39

41. realistic environment, the street. The bicycle was ridden by a team member to continue testing. Riding at
a slow rate still caused the LEDs to illuminate brightly, and as the speed increased, the brightness further
increased.
Next, the deceleration indicator needed to be tested. The bicycle was slowed using the hand
brakes to observe for deceleration. The LEDs flashed a few times as the bicycle was brought to rest from
a reasonable speed, operating exactly as hoped. This result was photographed and is displayed below:
Figure 26: Bicycle Test Run
The photo shows the LEDs constantly lit up as the bicycle moves. The indicator LEDs were
noticeable and prominent from a distance, and will definitely improve the safety of the cyclist.
40

42. 5. Cost Analysis
5.1 ­ ​Initial Investment
The initial component cost to develop the product prototype was $36.98. However, as
components are bought in large quantities directly from the manufacturer, this cost is reduced to about $8.
This significant price drop stems from the substitution of the microcontroller and accelerometer with
small chips of negligible value. This $8 price does not include manufacturing costs or other fixed/variable
costs. A total initial investment of $5,000 was estimated to include initial startup costs.
5.2 ­ ​Return on Investment (ROI)
Market research determined that the prospective market size for the product is about 500,000.
From this statistic, about 5% of the market was conservatively assumed to purchase this product within
the first year of its release, resulting in the sale of about 2,500 units. The product’s selling price is
competitively listed at $40, which would result in a weekly revenue of $1,900. After totaling the annual
total revenue and costs, the annual return of investment could be calculated at 174%. A graph of this
analysis is provided below:
Figure 27: ROI Analysis
The intersection of the revenue and cost projects demonstrates that the breakeven point will be
reached by week 5, leading to profit. The total projected revenue after one year is $1.6 million.
This cost analysis explains how this product is a worthwhile investment. With a reasonable initial
investment and a significant rate of return, this product is expected to be very successful in the targeted
market.
41

43. 6. Failure and Hazard Analysis
Failure and hazard analysis was conducted to determine potential threats that can arise in the
system. The analysis is divided into threats that can occur internally, a result of system failure, and threats
that can occur externally, a result of outside influence on the system.
6.1 ­ ​Internal Threats
The system is not at risk of any major hazards or failures from internal causes. The circuitry
operates at the specified voltages, and the inputs/outputs for each module performs exactly as theorized.
The internal system should operate normally unless external hazards are presented.
6.2 ­ ​External Threats
There are a few external threats to the system that can lead to potential failures in operation. Since
the device is mounted to a bicycle, it can be damaged by external factors such as physical impact or
unideal weather conditions. If the bicycle is affected by external factors, the circuitry can be damaged,
and the device can even be dismounted from the bicycle.
To help combat these concerns, the wires and components are safely secured to the bicycle to
increase durability. Duct tape and durable cardboard were used frivolously as primary protection
components for the device. Further improvements to the design to mitigate these concerns will be
discussed later in the report in recommendations.
There is also one hazard of this device that can potentially harm the user. If the bicycle sustains
high speeds for long durations, both the dynamo and the regulator generate large amounts of excess heat.
This heat will build up in the metal casing and heat sink at temperatures that could be hazardous to a user
if he/she were contacted directly. In order to reduce the possibility of user harm, the following precautions
were implemented:
● The regulator was placed in the center of the breadboard to avoid user contact.
● The dynamo was mounted towards the top of the rear wheel, a safe distance from the
user.
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44. 7. Recommendations
In order to continue to improve the effectiveness of this product, and to reduce the areas of
concern, a few additional steps should be taken.
The modules should be transferred from a breadboard to a more permanent printed circuit board
(PCB). This change would improve the reliability of the device and secure the components more
definitively. A PCB would also improve the convenience of installation for the user.
The system should be enclosed in a more durable casing to protect the components and improve
the reliability of the device. The system will be protected from external threats such as harsh weather
conditions or physical damage.
The digital control programming should be expanded to compensate for the directional angle of
the accelerometer. Added coding would include recalibration of the accelerometer either on startup, or
periodically to ensure the accuracy of the direction of acceleration. This would improve the
responsiveness of the indicator output, providing a more reliable deceleration output for the user. Also,
more logic can be included in the coding to make the sensor more or less sensitive, depending on what
would improve the device after further testing.
The number of LEDs in the array should be increased, and their configuration should be
reevaluated to further improve upon the cyclist’s visibility. When actually manufacturing the product for
sale, higher quality LEDs can be used that are more effective.
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45. 8. Conclusions
The goal of this course design challenge was to develop a useful product that harvests stray
energy from the environment, senses some parameter within that environment, and provides some level of
safety to the user. The bicycle deceleration indicator device is believed to have satisfied each of these
criterion. The device harvests stray energy from the rotation of the tires, senses the deceleration of the
bicycle, and improves the safety of the cyclist by increasing his/her visibility to others on the road. This
product is expected to be successful in the targeted market, and was developed in a cost­effective manner.
Throughout the design process, the following team oriented goals were accomplished:
1. The engineering design process was utilized.
2. The product was tailored to the targeted market’s needs.
3. The product’s successes and failures were evaluated, leading to several lessons learned.
4. The final product created can be taken pride in.
The designed product presents a solution to a realistic problem, and is believed to be thoroughly
successful. The development of this product was worthwhile, and the lessons learned can be used in many
future applications.
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46. Appendix A: Parts List
Qty Part No. Reference Description Distributor Unit ($) Subtotal ($)
1 COM­00526 REG 3.3V linear regulator Sparkfun 1.9500 1.95
1 COM­08982 C1
1000μF Electrolytic Decoupling
Capacitor Sparkfun 0.3500 0.35
1 COM­13689 T1 Transistor ­ NPN (BC337) Sparkfun 0.5000 0.50
4 COM­08589 D1­4 Diode Rectifier Sparkfun 0.1500 0.60
5 COM­00528 LED1­5 LED ­ Super Bright Red Sparkfun 0.9500 4.75
1 485­2019 ACCEL
Adafruit MMA8451 3­Axis
Accelerometer Mauser 7.9500 7.95
1
595­MSP­exp
430G2 MC
TI MSP­EXP430G2 Launchpad Dev
Kit Mauser 9.9900 9.99
1 POW31944M Dynamo Motorized Power Generator 6V 3W ebay 15.89 15.89
Table 9: Parts List
45

47. Appendix B: Computer Code
46

48.
47

49.
Figure 28: Digital Control Code
48