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Electric Assisted Bicycle
Table of Contents
ACKNOWLEDGMENT ..................................................................................................................................... 1
ABSTRACT ......................................................................................................................................................... 2
1 INTRODUCTION ............................................................................................................................................ 3
ELECTRIC PROPULSION TRENDS .................................................................................................................... 3
ENVIRONMENTAL BENEFITS ............................................................................................................................ 3
ELECTRIC EFFICIENCY ..................................................................................................................................... 4
2 PROBLEM STATEMENT .............................................................................................................................. 5
DESIGN ISSUES ................................................................................................................................................... 5
2.1 TASKS ASSIGNED TO INDIVIDUAL TEAM MEMBERS: ............................................................................. 7
Joe LaPointe:................................................................................................................................................. 7
Gregory Huh: ................................................................................................................................................ 8
3 DESIGN CRITERIA ........................................................................................................................................ 9
4 DETAILS OF DESIGN ...................................................................................................................................10
Motor Controller ..........................................................................................................................................11
Regenerated Braking ....................................................................................................................................12
Solar Panels..................................................................................................................................................13
HARDWARE DEVELOPMENT ............................................................................................................................14
Schematic of System......................................................................................................................................14
SOFTWARE DEVELOPMENT .............................................................................................................................15
Analog To Digital Converter ........................................................................................................................15
Pulse Accumulator ........................................................................................................................................16
Output Compare ...........................................................................................................................................16
4.1 FINAL SYSTEM:.............................................................................................................................................16
4.2 SOCIO-ECONOMIC ISSUES: .......................................................................................................................18
Cost Proposal ...............................................................................................................................................18
Cost of Time ..................................................................................................................................................18
Product Pricing ............................................................................................................................................19
Economic Benefits and Societal impacts ......................................................................................................19
4.3 SAFETY ISSUES: ...........................................................................................................................................20
5 TEST RESULTS AND DISCUSSION ...........................................................................................................22
6 CONCLUSION ................................................................................................................................................23
6.1 EXECUTIVE SUMMARY: ..............................................................................................................................24
7 REFERENCES ................................................................................................................................................25
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Electric Assisted Bicycle
ACKNOWLEDGMENT
This project would not have been possible if not for the valuable support and funding
from the Center for Engineering Education and Practice, College of Engineering and
Computer Science, University of Michigan-Dearborn.
The authors also wish to thank Associate Professor Dr. Natarjan Narasimhamurthi
and Graduate Advisor Dr. M. Shridhar for their help and advice throughout the
development of the project, and for their critical review of this report.
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ABSTRACT
Increasing demand for non-polluting mechanized transportation has revived the
interest in the use of electric power for personal transportation and also reduced
reliance on automobiles. A low cost alternative to an automobile is a bicycle.
However, the use of bicycles has been limited to very short trips or as a
recreational activity. This report describes the design of an electric assisted
bicycle that will extend the range of a typical rider. The system consists of three
source of power. The human effort of the rider pedaling the bicycle, and electric
motor running off a 12-volt lead-acid battery, and a solar panel that can charge
the battery when there is adequate sunlight. The power module is controlled by a
microprocessor, so that one can operate the bicycle at a preset speed (cruise
control). The power control module on the motor will reverse the current in the
motor if the speed of the bicycle is more than the desired speed. This current
reversal charges the battery, and thus provides regeneration not only when
braking as well as when going down hill, or when the rider pedals harder than the
set speed. The final system has features that will appeal to a broad spectrum of
users. Those who ride the bicycle for exercise can do so either by disabling the
electric assistance, or if they chose, by exerting more effort to generate electric
power and charge the battery. Those, who would otherwise not use the bicycle to
move around the city, can do so, confidant that there will be power assistance
when they grow tired, or when facing an uphill climb. The constant speed
operation will also provide a sense of comfort, especially when coming down
steep slopes.
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1 INTRODUCTION
The world’s car usage is booming. Cars are polluting the world’s cities, dumping
increasing amounts of carbon dioxide and other climate-altering greenhouse
gasses into the atmosphere, and consuming vast quantities of petroleum. The
alarming reality is that the automobile usage is growing at a much faster rate
than the human population, with saturation nowhere in sight. If present trends
continue, over 3 billion vehicles could be in operation by the year 2050,
exceeding 20 cars per 100 people. Even then, world car ownership rates would
fall far short of current U.S. rates of 70 cars per 100 people.
Electric Propulsion Trends
Electric vehicles cost more and perform worse than their gasoline counterparts.
This is mainly because gasoline cars have benefited from a century of intensive
development; electric cars have been virtually ignored for over seventy-five
years. Even today, gasoline cars profit from billions of dollars of research every
year while electric vehicles receive a tiny fraction of that.
Environmental Benefits
The primary premise for government support of electric vehicles has been air
quality. The sole legal justification for the EV mandate is controlling the pollution.
Electric vehicles will not disappoint on this count. But air quality alone is not
sufficient justification to mandate electric vehicles.
The single biggest
advantage of electric vehicles is that the electric power is produced in a
centralized location where the pollution can be better monitored and controlled.
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Electric Efficiency
Electric vehicles do, however, offer other strong benefits that are ignored by the
marketplace. One is the dramatic reduction in oil consumption and petroleum
imports that their widespread use would bring about. Much less oil would be
needed because only a tiny proportion of electricity is generated from oil-less
than 5 percent in the United States. The other major nonmarket benefit would be
lower greenhouse gas emissions.
The energy efficiency advantage is due to several factors. First, the overall
system efficiency taking into account the production of electric power,
transmission and distribution, local storage in batteries and conversion of electric
power to mechanical motion is estimated to be approximately 50%, while
combustion engine vehicles are 15 to 25 percent efficient. Second, about 10
percent of the energy used combustion engine vehicles is during idling; electric
vehicles consumes no energy during idling. Third electric vehicles can recapture
heat energy lost during braking. About one-third of the energy used by a motor
vehicle is lost during braking; electric vehicles can recover up to half that energy
with regenerated braking.
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2 PROBLEM STATEMENT
The problem to be solved is that of increasing the range of a human-powered
bicycle by equipping it with an electric motor running off a lead-acid battery. The
department of Electrical and Computer Engineering presently has mountain bike
equipped with an electric motor and battery kit manufactured by Zap World. The
kit consists of a permanent magnet DC motor, directly driving the rear wheel of
the bike, a 17 Ampere-hour lead acid battery and a battery charger that connects
to a standard wall outlet. This kit has been used in previous semesters for senior
design projects. An earlier project had designed a computer controlled power
management system. However, their design did not include a full regenerative
braking, and it was decided to redesign the power control module that can
provide regenerative braking. Also, the ease of integrating microprocessor-based
control was a primary goal of this project.
Design Issues
Motor control
In simplified terms, its terminal voltage controls the speed of a permanent
magnet motor. An efficient technique for controlling the terminal voltage is by
using a pulse-width modulation. Also, as the vehicle slows down, such as when
braking, the terminal voltage of the motor will be less than the battery voltage. To
absorb the kinetic energy of the vehicle and convert it to electrical energy and
charge the battery, some form of a DC-DC boost converter circuitry must be
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used. This boost converter will transfer power from a low voltage source to a
higher voltage sink.
Solar Energy
Since a bicycle would normally be used in daylight, it would be advantageous to
tap the solar energy to charge the battery. The solar panel used to convert the
solar power must have a high level of energy output without being too big and
cumbersome. One of the design goals was to size the solar panel so that the
battery can be charged in less than 4 hours while parked in bright sunshine. The
solar panel can be connected to the charging connector of the battery so that the
battery can also be charged from an electrical outlet using the battery charger
that is part of the kit.
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2.1 Tasks Assigned to Individual team Members:
Joe LaPointe:

Research different components in implementing the electric bicycle hardware
applications. This was mainly done by searching the Internet, researching
books and getting input from the faculty advisor.

Write cost proposals to obtain funding from the College for the project.

Research and incorporate EMC into the design.

Design and built a motor controller circuit (without regenerated braking).

Test/simulate electrical circuits on Electronics Workbench and P-Spice.

Test and simulate first stage designs, with actual components.

Visit motorcycle dealers in search of parts for the project.

Work on the wiring interface for the 68HC11.

Identify a commercial motor controller. Perform calculations for incorporating
the controller.
Design techniques to modify the commercial controller

Devise different approaches to implementing the variable speed controller.

Mounting and assembling of the electrical hardware on the bicycle.

Built a circuit for manual override of the microprocessor.
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Gregory Huh:

Study different options for electric vehicles, such as
an electric automobile,
Go-Cart, Scooter and the Bicycle.

Researched different approaches of controlling the vehicle. Mainly, using
different controller chips from Motorola and Unitrode in implementing the
design.

Called and obtained free samples of the controller chips from Motorola and
Unitrode.

Researched solar panels and made choices of the most suitable panel for the
project.

Wrote numerous cost proposals in order to obtain funding from the Dean for
the project.

Ordered components and solar panels, through Karen.

Designed a system for implementing the project through software.

Chose which interrupts to use and how to best implement the design through
software.

Researched the possible methods for writing and utilizing the EEPROM into
the design.

Wrote a test program for moving and storing data into the EEPROM.

Wrote a program to convert from Analog to Digital. This program controlled
the motor accordingly based upon the voltage input (Speed Control), through
the 68HC11.

In charge of the wiring of the bicycle, mainly minimizing the number of wires
running along the bike frame.
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3 DESIGN CRITERIA
The goal of this project is to design and build an electric bicycle, powered by a
12-volt battery, with an operating range between 28 to 33 miles. This goal can
only be attained by adding features designed to minimize the power consumption
of the system. All of the components used for obtaining the goal of the project
must be small enough to fit on the bicycle.
The first feature is to add pulse width modulation. The advantage of pulse width
modulation over the use of adding gears to the system is the fact that with gears
the gears, torque is gained, but distance efficiency is lost. Pulse width modulation
allows the motor to operate at a variety of speeds.
In order to obtain the pulse width modulation a microprocessor can be used to
trigger the motor. Since the microprocessor puts out a 5-volt signal at 2 mA, and
the motor runs off of 12 volts at a current of 20A, a motor controller must be
obtained to handle the voltage and current specifications.
Another feature of the design to add distance to the electric bike is regenerated
braking. Regenerated Braking is a system designed to recharge the battery as
the bike is braking or slowing down.
Another method of increasing the distance is to include solar auxiliary power.
Solar power is relatively free, except for the initial cost of the panels, and it is a
reliable source of energy. All these feature of the design must be within a cost
range of under $500.00.
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4 DETAILS OF DESIGN
To control the speed of a D.C. motor we need a variable voltage D.C. power
source. However if you take a 12v motor and switch on the power to it, the motor
will start to speed up: motors do not respond immediately so it will take a small
time to reach full speed. If we switch the power off sometime before the motor
reaches full speed, then the motor will start to slow down. If we switch the power
on and off quickly enough, the motor will run at some speed part way between
zero and full speed. This is exactly what a p.w.m. controller does: it switches the
motor on in a series of pulses. To control the motor speed it varies (modulates)
the width of the pulses - hence Pulse Width Modulation.
If the motor is connected with one
end to the battery positive and the
other end to battery negative via a
switch (MOSFET, power transistor
or similar) then if the MOSFET is
on for a short period and off for a
long one, as in A, the motor will
only rotate slowly. At B the switch
is on 50% and off 50%. At C the
motor is on for most of the time and only off a short while, so the speed is near
maximum. In a practical low voltage controller the switch opens and closes at
20kHz (20 thousand times per second). This is far too fast for the motor to even
realize it is being switched on and off: it thinks it is being fed from a pure D.C.
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voltage. It is also a frequency above the audible range so any noise emitted by
the motor will be inaudible. It is also slow enough that MOSFETs can easily
switch at this frequency. However the motor has inductance. Inductance does
not like changes in current. When implementing the system with a
microprocessor an RC circuit will be used it as a buffer between the
microprocessor and the controller circuit.
Motor Controller
Specifications
Supply voltage
Supply current
Output voltage
Output current (typical)
Braking current
Voltage drop at 20 Amps
Switching frequency
Size: (board only)
Size: (with heatsink)
Weight
Input
Input voltage
Full speed input
10v to 60v - 48v version
20mA (at zero speed)
0 to 100% full speed
100A (cold), 75A (hot)
80 A (cold), 75 A (hot)
140 mV
20 kHz approximate
122mm x 55mm x 30mm
. . . 180mm x 55mm x 35mm
100g 35 and 70 models
1k to 100k pot.
0v to full speed
adjustable 3v to 20v
Features

High speed MOSFET chopper circuit

Half Bridge

Fast current limit on drive and regeneration.

Adjustable gain

Regenerative braking

Current limit on drive and regeneration
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
CR type ramp

Heatsink is adequate for normal motor use (i.e. intermittent operation at
maximum output). The integral heatsink may be bolted to an additional
heatsink if required. The current limit reduces automatically if the
controller
gets hot, reducing the danger of failure.

Circuit can be used to drive loads such as lamps, which will work off a
chopped d.c. supply.
Regenerated Braking
Regenerated braking will be incorporated into the motor controller circuit. The
best way of thinking about it is that the controller is supplying a voltage to the
motor to drive it, and the motor is generating a back emf, proportional to its
speed. If the motor goes faster, its back emf rises and the current (caused by the
difference between the controller’s output voltage and the motor’s back emf) falls.
If the motor gets fast enough, the current falls to zero, as back emf equals
controller’s output. It the motor goes even faster then the current must go
negative (feeding back into the controller), as the back emf is now greater than
the controller’s output voltage. So braking starts to occur. The controller has to
do something with this current. Crude designs simply dump it as resistive heating
but it is more efficient (and not difficult) to feed the current back into the battery.
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Solar Panels
Electrical Specifications
MODEL
Maximum Power
Maximum Power Voltage
Maximum Power Current
Open Circuit Voltage
Short-circuit Current
Length
Width
Depth
Weight
KC40
40 Watts
16.9 Volts
2.34 Amps
21.5 Volts
2.48 Amps
526mm (20.7in.)
652mm (25.7in.)
52mm (2.0in.)
6.0kg (13.2 1bs.)
The conversion efficiency of the Kyocera solar cell is over 14% These cells are
encapsulated between a tempered glass cover and an EVA pottant with PVF
back sheet to provide maximum protection from the severest environmental
conditions.
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Hardware Development
The following schematic represents the hardware design of the system. The
schematic represents the outputs and inputs to the 68HC11, the output power
from the solar panel and the power going into the motor.
Schematic of System
The first step in the hardware design is to design the motor controller so it takes
a pulse from the microprocessor in order to drive the motor. The 2Qd controller
circuit was modified to take an input from 0 to 5 volts. This was achieved by the
addition of components to the 2Qd circuit. The values of these components were
calculated and configured into the controller circuit.
The solar panel was mounted and connected to the system with a diode to protect
the solar panel from receiving any back current. The solar panel was also
connected to a shunt regulator in order to receive current readings and voltage
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output readings. This also provided a reading for the power provided to the
system by the solar panels.
An infrared sensor was attached to the front tire of the bicycle. This allowed the
HC11 to keep track of the amount of revolutions pre second. The count of
revolutions per second is used in controlling the bicycle once cruise is activated.
Another controller circuit was designed and built to allow manual operation of the
bicycle or microprocessor driven operation during cruise control.
Software Development
The software for the project is written in Assembly language. The program is
interrupt/event driven. It utilizes three interrupts: A/D which gets the input from
the grip throttle/pot, Output compare, which is the signal input to the PWM signal
to the motor controller, Pulse Accumulator for obtaining the RPMs for the cruise
control.
Analog To Digital Converter
The analog-to-digital or A/D converter in the 68HCI I makes 8-bit unsigned
numbers representing external DC voltages. The A/D converter, by using an 8channel multiplexer, can read voltages from eight different pins on the 68HC II
package. Port E is the collection of the eight input pins for the A/D converter. An
A/D converter normally reads signals from analog sensors. Typical sensors
measure temperature, pressure, or position.
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An analog-to-digital converter makes a binary number that is proportional to an
unknown DC voltage. A digital-to-analog converter makes a DC voltage
proportional to a binary number. Generally, an A/D converter is much more
complex than a D/A converter, which is relatively simple and inexpensive.
Pulse Accumulator
The pulse accumulator either counts pulses on a pin or it counts cycles of an
oscillator to make a timer. The pulse accumulator operates in two modes called
the external-event-counting mode and the gated-time-accumulation mode.
The primary hardware in the pulse accumulator is an 8-bit up-counter. The port
A pin PA7 controls the counter.
Output Compare
The output-compare hardware normally controls the timing of changes in output
bits. Usually the output signal is nearly periodic; for example, a pulse-width
modulated waveform. However, almost any kind of timing can be achieved.
The 68HC II has five output-compare registers. Output compare I has
characteristics very different from those of output compares 2 through 5.
4.1 Final System:
In order to produce this design into a final product that can be marketed to the
public fabrication issues need to be addressed. The first step is to set up
suppliers to manufacture the necessary parts needed to build the electric bike.
These parts will include a wiring harness, which will be able to contain all weirs
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leading form the microprocessor in the front of the bike to the motor controller
circuit and from the motor controller circuit to the battery. Clips must be
manufactured to hold the wiring harness tightly to he frame so that the bicycle
riders will not get hung up o the wirers thus the system will be aesthetically
pleasing. A motor controller cover should be ordered to contain the motor
controller circuit. Along with this cover there should be a battery cover to prevent
electrical shock hazard. The Solar panels will require a mounting frame system
so that during a rough ride the solar panels will be secure.
Once the proper parts have been fabricated then an assembly factory must be
acquired in order to produce the finished product. In order to assemble the bike
the plant will need a staff off workers and supervisors. Also an administrative
staff must be put in place to oversee the business side of the operation. A
marketing team will also be needed to advertise and promote the product. Since
the European and Asian markets are more receptive to electric bicycles. It is in
the company’s best interest to set up international marketing schemes.
The software aspect of the product is immensely vital to the proper operation of
the system. The software needed to properly run the bicycle will be burned on to
a memory chip. This chip will be mounted on a circuit board that will compose of
a microprocessor, the 68HC11. The memory and the processor unit will be VLSI
circuits. Due to the high current in the rest of the controller hardware, VLSI will
not be possible and larger components and wires will be used.
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4.2 Socio-Economic Issues:
Cost Proposal
Parts and Price List
Part
Quantity Price
Microprocessor
Motorola 68HC12
Metal Box (EMF)
Ribbon Cable
(Total)
1
1
1
$160.00
$20.00
$10.00
$160.00
$20.00
$10.00
Solar Panels
KQ 40
1
Custom Made Frame 1
$295.00
$40.00
$295.00
$40.00
Motor Controller Circuit
Power Transistors
Power Diodes
Power Resistors
Bread Board
Cables
Relays
Misc. Parts
12
6
10
2
1
4
--
$5.00
$4.00
$2.00
$15.00
$10.00
$5.00
$50.00
$60.00
$24.00
$20.00
$30.00
$10.00
$20.00
$50.00
Controller Chips
Unitrode 3678
3
$4.00
$12.00
Control Mountings
Grip Accelerator
Misc. Mountings
1
--
$50.00
$40.00
$50.00
$40.00
Sub Total
$1037.00
Tax, Shipping and Handling
Tax
6%
S&H
--
$93.36
$120.00
Total part Cost
$93.36
$120.00
$1250.36
Cost of Time
Student/Faculty
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Time
Rate
18
Total
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Joe LaPointe
Total
15hrs./Week $10.00
30 weeks,450 Hours
$4,500.00
Greg Huh
Total
15hrs./Week $10.00
30 weeks,450 Hours
$4,500.00
N. Narasimhamurthi 5hrs./Week $100.00
Total
30 weeks,150 Hours
$15,000.00
Total Team
$24,000.00
1050 Total Hours
Fringe Benefits at 30% of Total Hourly Cost
$7,200.00
Total Cost of time
Facility Rental
$31,200.00
500 hours @ $10/hour
Total Cost
$5,000.00
$37,450.36
Product Pricing
In order to recover the initial investment capital and production cost, we would
have to sell the following amount of units at the designated price.
Number of units to be sold:
500 units
Unit price:
$1,100.00
Profit Margin after all expenses including Production,
Shipping and Marketing
$100.00
Revenue
$550,000.00
Profit
$12,549.64
Economic Benefits and Societal impacts
This project involves the implementation and studies of the electric vehicle. This
is of primary importance because of current world trends. Oil and gasoline is
being consumed at a much higher rate than it is being produced. In some
countries gasoline prices are as high as 4 dollars per gallon. This is an outcome
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that the United States will eventually face and one that will get worse before it
gets better.
Differences that exist between electric motors and gasoline motors include the
following. Although a gasoline motors can put forth much power with a small
engine they are only about 30 to 40 percent efficient. Electric motors on the other
hand are around 90 percent efficient. Another important fact is that oil takes
millions of years to produce and is limited resource electricity can be
spontaneously produced and is not considered to be a limited resource. One
more advantage that electricity has is that it poses very little threat to the
environment.
4.3 Safety Issues:
There are many safety issues that in tail this project. The first is that of bicycle
safety itself. When one is riding on a road or traffic filled street unless the bike
can keep up with the speed of that street they should ride along the shoulder of
the street. It is recommended that when riding on the shoulder of the street that
one rides against the flow of traffic. If something should occur there is more
reaction time for the bicyclist. One can also be aware of whether drivers are
aware of your presents. Also when riding a bicycle and even more important
when riding an electric bicycle, a bicycle helmet should be worn. And when riding
on city or country roads always obey the traffic laws.
Another safety concern of this electric bicycle is that it should not be driven in the
rain. If the motor controller circuit gets wet it may fry the MOSFET transistors.
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Although a protective cover is placed over the circuit, in heavy rainwater could
still make its way up into the circuit. It is also recommended that the electric
bicycle be not ridden through puddles or wet terrain because of the tires
tendency of throwing water up onto the bike.
When servicing the bicycle only authorized personnel should do so. Since the
motor takes a 20 amp current when the battery is fully charged there is a risk of
electrocution. Small children should not be allowed to ride the bike. It is our
recommendation that the age requirement be 12 years and older in order to
operate the bicycle.
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5 TEST RESULTS AND DISCUSSION
The tasks and goals of the design team were all accomplished. These included:
variable speed control, microprocessor control, cruise control, and solar panel
auxiliary power. The bicycle worked in both modes of operation, manual or
automatic.
Although some tests were performed on the system, such as solar power output
and power consumption by the bicycle at full speed. The power produced by the
solar panels is tested to be relatively close to the manufacturer specifications.
Our tests produced 15.6 Volts and a current of 2.16 Amps in direct sunlight.
These figures translate into a power supply of 34 Watts. The maximum power
consumption of the bicycle is tested to be at 20.5 Amps at a voltage of 11.56
volts. This gives a power consumption of 237 Watts.
There was not enough time to perform the extensive testing that would be
necessary in order to fully state bicycles capabilities. This inability to fully test the
system was mainly due to time constraint placed on the team.
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6 CONCLUSION
During the past two semesters the electric bicycle project has provided an
opportunity to grasp the full scope of what it means to Design a product. This
opportunity allowed an initial idea/goal to be realized in a team environment.
The idea developed as research and various other information on the topic was
obtained.
The project evolved and changed as the team limitations and financial
constraints were realized. Due to a lack of funding, the initial design of an
electric go-cart was downsized to the current project, the electric assisted
bicycle.
The initial design, of the electric assisted bicycle, carried along with it constraints
that had to be worked around. The constraints were mainly financial in nature.
They represent pieces of equipment in the design that had to be carried over
from other semesters. The constraints on the equipment consisted of the
battery, motor, and the bicycle frame. The motor bicycle relationship could not
be altered, mainly due to the type of mounting on the motor. These constraints
limited, but did not totally restrict the teams ability to design a “new” system.
Once all constraints were known, the goals for the design were clearly identified.
The goals were divided among the team members. In order to meet the deadline
for the final project, progress was monitored weekly and individual goals were
readjusted as needed.
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With communication between the team, and hard work, the final objective was
obtained. The design project provided the team with valuable experience in
design and teamwork. It allowed the team members to develop skills that will be
useful in future endeavors.
6.1 Executive Summary:
1. Name and academic rank: Gregory Huh, Senior at University of Michigan
2. Degrees with field, institutions and dates: Diploma 1994, Axtell High
School (College Prep.)
3. Number of years of service at University of Michigan: 3 years
4. Other related experience: Lab Proctor ECE 373 1/01/99 – 12/12/99Intern at
Dearborn Group 1/6/99 – 9/9/99
1. Name and academic rank: JOE LAPOINTE, Senior at University of
Michigan
2. Degrees with field, institutions and dates: Diploma 1982, South Lyon High
School (College Prep.)
3. Number of years of service at University of Michigan: 2 years
4. Other related experience: Interfaced musical hardware systems.
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G. Huh and J. LaPointe
Electric Assisted Bicycle
7 REFERENCES
1) Adle S. Sedra/Kenneth C. Smith, “ Micro Electronics Circuits, Fourth Edition”,
Oxford university Press, 1998.
2) Motorola, “M68HC11EVB Evaluation Board User’s Manual”, Motorola, 1986.
3) J. David Irwin, “Basic Engineering Circuit Analysis”, Prentice-Hall, Upper
Saddle River, New Jersey, 1996.
4) Daniel Sperling, “Future Drive, Electric Vehicles and Sustainable
Transportation”, Island Press, 1995.
5) 4QD, “Motor Controllers”, http://www.4qd.co.uk/prod/2qd.html
6) Fredric M. Cady, “Software and Hardware Engineering”, Oxford University
Press, 1997
7) Gene H. Miller, “Microprocessor Engineering”, Prentice-Hall, 1993
8) Mazzae, Elizabeth N; Barickman, Frank S. “Intelligent transportation Systems
(ITS) Research”, Vehicle Research and Test Center,
http://www.nrd.nhtsa.dot.gov/vrtc/ca/its.htr
9) Occupational Safety and Health Adminisration “OSHA Regulations for Motor
Vehicles” http://www.osha-slc.gov/OshStd_data/1910_0303.htrr
10) United States Patent Office, “Patent Search”, http://www.ibm.patent.com
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