19004 Practice school finalReportformat Model (1).pdf
Converting Go-Kart to Battery Powered
1. 1
Converting Internal Combustion Go-Kart to
Battery Powered Go-Kart
Watson Capstone Project 10
Sponsor: Raymond Corporation
William Paulson, ME
Chase Bouchard, EE
Antony Haines, ME
John Stefanidis, ME
Ben Barone, EE
Faculty Advisor: Guangwen Zhou
External Advisor: Dan Driscall & Fernando Goncalves of Raymond
April 29, 2016
Revision: 1.0
Submitted in partial fulfillment of the requirements of ME 493/EECE 487
in the Spring Semester of 2016.
Thomas J. Watson School of Engineering and Applied Science
State University of New York at Binghamton
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Executive Summary
Problem Definition:
Economic and environmental changes have increased the demand for electric drive systems in
vehicles. Electric vehicles are desirable because electricity can be generated renewably, and can come
from a clean energy source. Electric vehicles are also more energy efficient than their internal combustion
counterparts. This project is a practical experiment to explore the process of converting a gas powered
vehicle to an electric vehicle.
The goal of the project is to convert a gas powered go-kart into an electric go-kart. The Raymond
Corporation has provided a functional gas powered go-kart, and all of the functional components
necessary to design and implement an electrical system. First, a series of performance tests on the gas go-
kart were run and documented. The team used the results of these tests to design and construct an
analytical model of the kart. The model was used to determine the key design parameters for the electric
go-kart that would enable the electric kart meet or exceed the performance of the gas go-kart. Then, the
electric system was designed, fabricated and assembled. Finally, the same performance tests were
repeated on the electric go-kart.
Design Description:
In the first semester,a mathematical model to predict the performance of the electric go-kart was
designed. This model was used to select the gear ratio and electric power settings to be used on the go-
kart once it is converted to an electrical vehicle.
In order to collect performance data, we designed and built a digital speedometer using a Hall
Effect sensor and an Arduino microcontroller. We used this to benchmark the gas go-kart. The data
collected, along with torque curves provided by Raymond, were used to construct a mathematical model
of the electric kart system. Using this model, the design parameters were selected such that the kart’s
performance would meet or exceed the requirements.
The second semester,the conversion hardware was designed and fabricated. This included a
circuit design, motor mount, battery mounts, and mounts for the controller and electrical components.
The mechanical designs were pre-tested using PTC Creo’s finite element analysis, and iterated to
minimize weight while maintaining a strength safety factor of 2. The mounting hardware was fabricated
in the Watson School Student Shop, and the wiring was completed at the Raymond facility in Greene.
Finally, the electric kart was benchmarked under the same conditions as the gas kart.
Budget and Schedule:
The final costs were $122 under-budget, and the final kart prototype was completed two weeks
ahead of schedule. Time and cost savings were realized by finding local sources for materials and parts,
which avoided shipping surcharges and wait time.
Future Plans:
If we were to continue this project, severaldesign improvements could be made, mainly to
improve ease of use and driver comfort. The weight distribution could be fine-tuned. Also, the
speedometer/odometer could be improved to add onboard data storage.
With this practical knowledge of the gas-to-electric conversion process, and first-hand experience of the
advantages and disadvantages of each system,we will have advantage in the field of electric vehicle
engineering.
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Table of Contents
1. Problem Definition...................................................................................................................... 6
1.1 Problem Scope ...................................................................................................................... 6
1.2 Technical Review.................................................................................................................. 6
1.3 Design Requirements ............................................................................................................ 7
2. Design Description...................................................................................................................... 9
2.1 Overview............................................................................................................................... 9
2.2 Detailed Design Description ............................................................................................... 11
2.2.1 Sensor & Display Hardware ........................................................................................ 11
2.2.2 Sensor & Display Software.......................................................................................... 14
2.2.4 Mathematical Model of Electric Kart .......................................................................... 18
2.2.5 Battery Mounts............................................................................................................. 19
2.2.6 Motor Mount................................................................................................................ 22
2.2.7 Accelerator Transponder.............................................................................................. 23
2.3 Use ...................................................................................................................................... 23
2.3.1 Data Acquisition .......................................................................................................... 23
2.3.4 Mathematical Model of Electric kart ........................................................................... 24
2.3.5 Battery Mounts............................................................................................................. 24
2.3.6 Motor Mount................................................................................................................ 24
2.3.7 Components Box.......................................................................................................... 24
2.4 Conclusions Drawn from Mathematical Model.................................................................. 25
3. Implementation ......................................................................................................................... 25
3.1 Sourcing Material................................................................................................................ 25
3.2 Mounting Hardware Fabrication......................................................................................... 26
3.3 Wiring ................................................................................................................................. 26
3.4 Accelerator Transponder..................................................................................................... 27
4. Evaluation ................................................................................................................................. 27
4.1 Testing................................................................................................................................. 27
4.2 Test Results......................................................................................................................... 28
4.2.1 30-0 mph Deceleration................................................................................................ 28
4.2.2 Efficiency..................................................................................................................... 29
4.2.3 Top Speed .................................................................................................................... 29
5. 5
Full Rear Sensor Support ...................................................................................................... 64
Sensor Support: Bearing ont ................................................................................................. 65
Sensor Support: Hall Effect Mount....................................................................................... 66
F.2 Motor Mount....................................................................................................................... 67
Motor Mount Assembly........................................................................................................ 67
Back Plate ............................................................................................................................. 68
Bottom Plate.......................................................................................................................... 69
Front Plate............................................................................................................................. 70
Gusset.................................................................................................................................... 71
Chain Guard .......................................................................................................................... 72
F.3 Battery Mounts ................................................................................................................... 73
Front Pipe Support ................................................................................................................ 73
Rear Pipe Support ................................................................................................................. 74
Side Mount Assembly........................................................................................................... 75
Side Mount Long Wall.......................................................................................................... 77
Side Mount Short Wall ......................................................................................................... 78
Separator ............................................................................................................................... 79
Battery Strap Tab .................................................................................................................. 80
Battery Strap ......................................................................................................................... 81
Front Mount Assembly ......................................................................................................... 82
Front Mount Base Plate ........................................................................................................ 83
Front Mount Long Wall ........................................................................................................ 84
Front Mount Short Wall........................................................................................................ 85
Front Mount Support Leg 1 .................................................................................................. 86
Front Mount Support Leg 2 .................................................................................................. 87
Appendix G: Mathematics of Computer Model ........................................................................... 88
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1. Problem Definition
1.1 Problem Scope
The goal of this project is to convert a gas powered internal combustion (IC) go-kart to an
electric powered kart without any decrease in performance. The Raymond Corporation
has provided the team with a fully functional gas powered kart and the required
components necessary to convert the kart. These components include an electric forklift
motor, 12V batteries, and an electric motor controller. Before converting the kart, the
team tested and documented the IC go-kart performance. These test and performance
requirements can be found in Appendix A: Project Proposal. The performance of the
electric powered kart must exceed or match that of the IC kart. Using the data and tests
done on the IC kart, a mathematical model of the electric kart’s predicted performance
was created. We used this model to determine the configuration of the electric system.
Once the desired configuration was chosen, the mounting hardware was designed and
fabricated, and the converted kart was benchmarked and tested once again.
1.2 Technical Review
Recently there has been a shift from using the internal combustion engine to the use of
electric motors in automobiles. One of the main advantages is that electricity can be a
clean and renewable energy source, and electric vehicles cause minimal pollution. In an
internal combustion engine, the fuel is combusted and released as exhaust into the
atmosphere where it is unable to be used again and causes harm to the atmosphere. These
byproducts release a large amount of pollution in our atmosphere and contribute to global
warming.
Electrically powered engines are also quieter and simpler than internal combustion
engines. An electric engine applies instant and maximum torque at zero RPM, which
greatly increases acceleration and simplifies power transmission. Additionally, due to the
lack of combustion, electric engines do not vibrate as violently as IC engines. Electric
drive vehicles can also utilize regenerative braking, which saves energy and increases
their efficiency.
Although electric engines are more environmentally friendly, energy efficient, and
accelerate more quickly, there are disadvantages. Batteries are much heavier than a tank
of gas, which lowers efficiency in city traffic. Also, an internal combustion engine
vehicle gets better range on one tank of gas than a typical electrical engine vehicle can in
one charge. Most electric cars on the road today cannot drive more than 100 miles on a
single chargeAnother factor is refueling time; a gasoline tank can be refilled in a few
minutes, while a battery bank can take hours to recharge. Battery technology is a fast-
advancing field, and as new technologies are developed, this disadvantage will likely
disappear.
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1.3 DesignRequirements
See Appendix B for a complete list of requirements.
The primary goal of this project is to convert an internal combustion system to an electric
one, and have the new system operate as well as or better than the old system. The
requirements list is broken up into Mechanical, Electrical, and Miscellaneous
requirements. Listed below are quantitative requirements for the electric go-kart, which
are based on performance testing completed on our combustion engine go-kart. The
results of the tests on the IC kart for these requirements provide the benchmarks for the
electric go-kart.
WCP10-R-05
The 30-0mph braking distance and time of the electric go-kart shall be
comparable to the gas benchmark.
Value: Within 20% (ft, sec)
Description: Requirement WCP10-R-05 was provided in the project proposal and
can be seen in section 5 of Appendix A. Our goal is to match the braking ability
of the IC kart after installing the electrical components for the EV kart. It is
expected that once the electric components are installed the weight of the kart will
increase significantly. This requirement will help ensure that the driver will still
be able to stop within a reasonable distance and time without causing damage to
the kart or themselves.
WCP10-R-10
The electric powered kart shall be as efficient as the gas-powered go-kart.
Value: Within 15% (Miles, Gas Gallon Equivalent)
Description: Requirement WCP10-R-10 was provided in the project proposal and
can be seen in Section 5 of Appendix A. The efficiency of electric motors is a big
reason for the shift from gasoline powered engines to electric motors. Our final
design has to be at least as efficient as the gasoline powered version of the go
kart.
WCP10-R-14
The top speed of the electric go-kart shall meet or exceed the benchmarked speed
of the gas kart.
Value: Benchmark Value
Description: Requirement WCP10-R-14 was provided in the project proposal and
can be seen in Section 5 of Appendix A. The electric kart will be expected to go
faster than the gas-powered kart.
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WCP10-R-15
The weight distribution of the electric go-kart should match that of the gas kart.
Value: Within 20% (pounds)
Description: Requirement WCP10-R-15 was provided in the project proposal and
can be seen in Section 5 of Appendix A. The weight distribution plays an
important role in the balance of the kart. If too much weight is distributed to one
side of the kart the chance of overturning it increases. In addition, too little weight
on the rear axle could cause the tires to spin, and too little in the front causes
handling problems. In order to ensure the safety of the driver the weight
distribution should remain within 20% of the gas kart so that kart remains
balanced. In addition, the total weight of the kart will be used in the calculations
to help predict the theoretical performance of the electric kart.
WCP10-R-16
The electric go-kart shall accelerate from 0-30mph within 1/8 of a mile.
Value:
Description: Requirement WCP10-R-16 was provided in the project proposal and
can be seen in Section 5 of Appendix A. The criteria provided in this requirement
will be used to baseline the gas kart. The result of the test for acceleration of the
gas kart will be used as the benchmark that the electric kart will need to
outperform. The test results for this requirement will be used in calculations to
predict the theoretical performance of the electric kart.
WCP10-R-17
The electric go-kart shall complete the autocross course in a comparable time to
the gas powered kart.
Value: Within 20% (seconds)
Description: Requirement WCP10-R-17 was provided in the project proposal and
can be seen in section 5 of Appendix A. The criteria for the completion time of
the autocross course will be used to test the final design of the electric kart. The
autocross course will show whether our final design is better at handling around
turns.
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2. DesignDescription
2.1 Overview
The design goal was to convert the gas go-kart into a electric cart that met or exceeded
the performance of the gas kart. During the early stages of the project we benchmarked
our gas kart using a speedometer, data capturing software and scales. We used this data to
create a math model that would be used to model the performance of the electric kart.
The model was used to optimize the conversion from an IC engine to an electric motor
kart. The components that were chosen include the number of batteries (this determines
available voltage), the gear ratio, and the motor controller current. The motor, motor
controller and battery parameters, as well as any specifications of these components were
provided by The Raymond Corporation. Measured data was needed in order to create a
functioning computer model. Collection of this data was determined by the following
benchmarks.
1. Top speed
2. Acceleration: 0-30 mph, 1/8mi
3. Braking: 30-0 mph
4. Curb weight and balance
5. Auto-cross course
6. Fuel consumption/efficiency
In addition to benchmarking the kart, important vehicle parameters needed to be
measured, including tire diameter, rolling resistance, vehicle mass, braking torque, and
the coefficient of friction between the rubber tires and asphalt. To measure the
benchmarks, instrumentation was designed and built along with a microcontroller
program which filtered our data into a usable form. The remaining parameters were
measured using a variety of tools and formulas. Once all the benchmarks and parameters
had been measured, the math model with a simple graphical user interface (GUI) was
designed.
The mathematical model took the design parameters as input, and output the predicted
performance of the electric kart. By adjusting the parameters and observing the results,
parameters were selected that would fulfill the design requirements. The motor spur gear
was selected to be a 29-tooth gear; the maximum DC voltage selected to be 36V using
three 12V batteries; and the controller current was selected to be 400A.
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The entire system diagram is shown below in Figure 5. The eventual electrical system
can be broken up into four subsystems which are braking, power, steering and
instrumentation.
Figure 1. Electric Go-Kart System Diagram
In semester one, the focus for the team was to create a cost effective, efficient and
accurate instrumentation system to record speed and distance data. The instrumentation
system design is shown in Figure 6.
Figure 2. Instrumentation System Diagram
The first subsystem within the instrumentation system is the rare earth magnets. Six of
these magnets were attached, equally spaced around the rear axle. A Hall Effect sensor,
described in detail in Section 2.2.1, was mounted directly above the magnets. The sensor
is able to detect a voltage spike when it passes through a magnetic field. Theses voltage
spikes are then recorded against time by an Arduino Uno, which converts the data into
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revolutions, which in turn can be converted to rpm, speed, acceleration, and distance
traveled. We used this data to benchmark the kart.
The mounting hardware to secure the motor, batteries, controller, and electrical
components to the kart’s frame were designed based on the results from the mathematical
model, test results, and measurements. CAD models for all the mechanical components
were developed, and the loads the parts would have to bear were calculated. Using PTC
Creo, finite element analyses were performed to calculate the deformation and stresses of
the parts, and based on these analyses, the thickness of steel required to give minimal
deflection, minimal weight, and a deformation factor of safety of 2 was determined.
In addition to the mounting hardware, the final circuit diagram of the electric system was
developed, and an accelerator potentiometer assembly was designed.
2.2 Detailed DesignDescription
2.2.1 Sensor & Display Hardware
To measure speed, acceleration and distance traveled, a Hall Effect sensor was
used. A Hall Effect sensor is a transducer whose output voltage varies based on
magnetic field. An application of this property is detecting the RPM of a rotating
axle by attaching a magnet to the axle so that the output voltage of the sensor will
spike when the magnet passes by it thus recording a revolution of the axle. The
optimal distance between the magnet and the sensor, giving the most accurate
readings, was approximately a quarter of an inch. This application could be used
to determine the revolutions of the rear wheels of the go-kart.
Six magnets were mounted, to increase the resolution of the data. They were
evenly spaced and epoxied onto the rear axle. A mount was 3D printed to rigidly
hold the sensor the optimal quarter inch from the magnets. A 3D model of the
rigid mount can be found in Appendix F. The sensor mount was designed using
PTC Creo 3.0 and the 3D printing was completed in the ETS lab in the Computer
Center at Binghamton University [3]. When completed, the mount was epoxied to
the two rear axle bearings. This position was chosen because it provides structural
rigidity directly above the rear axle.
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Figure 3. Sensor Mount on Back Axle
The mount was printed in two separate parts. The first part is the pink box
mounted across the two bearings located on the axle. The box contains two holes,
one in the sidewall and another in the bottom centered above the magnets. These
holes allow the cable connecting the sensor to the Arduino to be positioned
directly above the magnets and held in place. The second part is the blue, four
legged apparatus pictured above. It contains a small hole where the four legs
converge. This hole is just large enough for the Hall Effect sensor to fit through,
and provides a rigid body to reduce chatter in the collected data. It was epoxied to
the rectangular portion in such a way that when the Hall Effect sensor was fixed
in position, through the hole at the top, it was optimally located to detect the
magnets.
The Sensor and Display hardware fit into a 4.69in x 3.72in x 2.05in aluminum
box. It was large enough to accommodate all the necessary circuitry in such a way
that none of the parts interfered with one another, while also being small enough
that there is no room for the circuitry to come loose during testing. Contained
inside the box was the LCD display, the Arduino Uno circuit board, a small
breakout board and any necessary wires for the connections. The final
configuration can be seen below in figure #.
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Back of LCD
Display
Front of LCD
Display
Breakout
Board
Arduino
Uno
Figure 4. Inside and Front View of Display Hardware
The Arduino Uno could be programmed to show any desired readings calculated
in the software on the LCD display. The complete code for the Arduino can be
found in Appendix D, and a more detailed description of how the readings were
calculated is located in the next section. It was decided that the instantaneous
speed of the go-kart and the rpm (revolutions per minute) would be displayed on
the LCD.
A detailed wiring diagram of the connected portions shows how the Hall-Effect
sensor, Arduino, LCD display and potentiometer are connected.
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Figure 5. Complete Sensor Circuit Diagram
The Hall Effect sensor connects to the Arduino board through a triple core 10ft
cable. The sensor’s 3 pins were soldered to the cable at one end, while the other
end was soldered to the breakout board. The LCD display and potentiometer were
also soldered to the breakout board to match the diagram above. Wires attached to
the cable and ground of the Arduino were then attached to the breakout board
powering the Hall Effect sensor, display and potentiometer. The most important
connection, providing the information required to collect our data, is the output of
the Hall Effect sensor. This output was connected to the breakout board via the
tri-core cable and then diverted to pin 2 of the Arduino.
2.2.2 Sensor & Display Software
Storing and collecting data on the performance and efficiency of the kart was
dependent upon the ability to detect the revolutions of the rear axle. A script was
written, using the Arduino coding platform, to record the outputs of the Hall
Effect sensor and transform them to wheel revolutions. The voltage output of the
Hall Effect Sensor spikes when a magnet is run by it. The number of spikes was
measured for a specific sample time that gave the optimal amount of data points
without sacrificing for accuracy. After trial and error, a
was chosen that met the requirements. Once the number of revolutions over a
specific period could be determined, rpm, velocity, and distance traveled could be
calculated. The equations used to solve for these include
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Calculating the total distance required the amount of revolutions during each
specific sample time. A temporary distance value is calculated for every sample
taken. These temporary distances are constantly being added to get the total
distance traveled.
The output of the Distance was in feet, but could be calculated to any
measurement that was desired.
2.2.3 Electrical Kart Circuitry
Figure 6. Circuit Diagram
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The circuit used to power and control the kart involves the use of three 12V
lithium ion batteries, a motor controller, main contactor coil, several 12V relays,
battery management system (BMS), shunt, voltage regulator, potentiometer, and a
forward/reverse, key and emergency switch. The system uses several different
gauges of wire depending on the current drawn from each component. This circuit
is powered by the three 12V lithium ion batteries connected in series. They are
each rated at 100 A/hr and output a maximum of 400 Amps. Each battery is made
up of twelve separate cells that need to be balanced and work in sync so that the
batteries work optimally. The batteries power the motor controller and the BMS,
however the BMS can only be powered by 12V so a voltage regulator is used as
an intermediary between the two. By describing how the BMS works, we will be
able to examine many of the other components used within the system.
The BMS is integral in the safety and reliability of the circuit. It is connected to
several components and takes in a multitude of inputs, while also monitoring the
batteries. The BMS, despite needing to be powered with the 12V from the voltage
regulator, also needs to take in the output from the positive end of the batteries in
series. It also takes in the inputs from the shunt called SH+ and SH-. The shunt is
used to monitor the current of the batteries. One contact of the shunt takes in the
negative side of the battery chain, while the other contact is connected to the input
terminal of our under voltage relay. It should be noted that the output terminal of
this undervoltage relay is connected to the B- terminal of the controller,
completing the circuit allowing the shunt and in turn the BMS to measure current.
Another input to the BMS is the sense board input. The three batteries have
special contactors that connect in series and then to the BMS. This sense board
input allows the BMS to monitor the 12 cells in each battery.
The BMS has two outputs that are integral in keeping the batteries safe and in
working condition. These are the undervoltage (UV) and overvoltage (OV)
outputs. The under voltage terminal on the BMS outputs 12V, which drives two
relays. The first relay is a generic 12V relay that could be found at any auto parts
store. This relay is powered directly by the UV output of the BMS and when
closed, feeds 12V to our undervoltage relay. This powers the undervoltage relay
which in turn closes and feeds power to motor controller. To summarize, when
the kart is turned on with our key switch, the BMS powers our two relays through
its UV output of 12V, then the relays feed power to the motor controller allowing
the kart to function. When the BMS detects dangerously low voltages from the
batteries it no longer outputs 12V from UV and instead outputs 0V. This makes
sure that no more voltage can be drawn from the batteries, ensuring their safety.
The OV output of the BMS powers another one of our 12V relays, which is called
our overvoltage relay. The input terminal of this relay is connected to a charger
connector, which in turn is tied to the negative terminal of our batteries. The
output of this overvoltage relay is connected to the positive side of the batteries.
The relay stays closed as long as the OV output of the BMS is 12V. The output of
this OV terminal will become zero when the BMS detects that the batteries are
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fully charged. This is important when the charger is connected and it prevents
overcharging.
We used a Curtis 1236 AC induction motor controller to govern the performance
of our electric motor.
Figure 7. Curtis Motor Controller
This vehicle control system has a field-programmable logic controller, which was
extremely convenient when making throttle adjustments in the field. We mounted
the motor controller on the floor of kart under the steering wheel column. This
was an ideal mounting location because it is recommended that the controller be
fastened to a clean, flat metal surface. Additionally, this area is well protected by
the driver’s legs, helping to keep it clean and dry. This controller has five contact
points. The first two points are a B+ and a B-, connected to the positive and
negative terminals of the battery respectively. The other three connections are the
Motor phase U, V, and W connections. These connections create the three phase
power supply system that makes it possible to produce the rotating magnetic field
in the electric motor. The motor controller has a single 35-pin AMPSEAL
connector to make all of the low power connections. These low power
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connections included the output from the potentiometer, position encoder and
temperature sensor from the motor, output from the forward/reverse switch and
the input to the handheld controller used for programming.
2.2.4 Mathematical Model of Electric Kart
In order to make design decisions about the electric kart conversion, a
mathematical model of the electric kart was constructed using MATLAB. The
model is based on motor torque curves provided by Raymond Corporation, and
data from measurements and tests carried out by the team. The model accepts
design parameters through a graphical user interface, and calculates the predicted
performance with those parameters. The parameters were selected such that the
predicted response of the electric kart would fulfill the design requirements.
Figure 8. Mathematical Model GUI
The measurements the model uses to derive its output include kart weight (laden
and unladen), rear axle slip torque, and coasting deceleration. A full description
of the reference data, calculations, and equations used is included in Appendix G,
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and the MATLAB code that carries out the computations is included in Appendix
E.
The parameters include the weight of the frame, batteries, and driver; the voltage
and current; and most importantly, the number of teeth on the electric motor’s
drive sprocket; which determines the gear ratio. Selecting the right gear ratio is
the most critical design decision. The voltage and current selections are limited to
the options available within the constraints of requirements WCP-R-09, 11, 12
and 13; the gear ratio is only limited by the availability of sprockets with a given
number of teeth.
The output of the model shows the resultant wheel torque vs. motor RPM,
determined from the motor torque curve and the gear ratio. This is overlaid with
the maximum allowable wheel torque before the wheels will slip. The design
goal is for the wheel torque to slightly exceed the slip torque, so that the
maximum acceleration attainable with rubber wheels on asphalt is available. The
output also displays the predicted acceleration of the electric kart against a
benchmark from the gas kart tests, and the predicted braking behavior.
2.2.5 Battery Mounts
Originally the two battery mounts were designed using 1/8” steel sheet metal.
After running FEA on the two battery mounts in Creo Parametric 3.0 it was
determined that this thickness of steel sheet metal would be sufficient to hold the
batteries. Though this thickness would suffice the decision was made to fabricate
the battery mounts using the same 3/16”steel sheet metal as was used for the
motor mount. This would increase the overall weight of the mounts but this
increase in weight would be negligible compared to the increase in strength of the
mounts.
The mounting locations of the batteries were chosen to maintain the weight
distribution of the electric kart as close to the weight distribution of the gas
version of the kart. The electric components were mounted in locations similar to
where the gas components were once mounted. Two of the batteries were
mounted on a single mount on the left side of the kart between the front and back
wheels and the remaining battery was mounted at the front of the kart below the
air shield. The battery at the front end of the kart would somewhat mimic the
weight of the gas tank and the two batteries on the left side would counter the
weight from the electric motor mounted on the right side of the kart. After the
mounting locations of the batteries were chosen, the correct sized U-shaped
clamps were used to hard mount the two battery mounts to the frame of the kart.
One of the mounting clamps for the front mount was not made in the correct size
to fit around the frame where the back leg of the front battery mount was to be
clamped down. Instead two ¼” bolts and a rectangular washer were used clamp
this part of the mount to the kart.
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Front Mount
Figure 9. Front Mount Model
Four one-inch high walls were welded to the top edges of a rectangular base plate
to form an open box. Three L-shaped legs were welded to the bottom of the base
plate to raise the bottom surface of the base plate over a tab used to secure the
front air shield in place. The legs kept the base plate and thus the battery parallel
to the ground. Slots were cut into the feet of the legs so that clamps could be used
to hard mount the front battery mount to the frame of the kart. Two additional tabs
were added to the front top left corner and back top right corner of the walls,
which would be used in conjunction with a one-inch wide bar cut from the 3/16”
steel sheet metal and two threaded rods to bolt the batteries to the mount.
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Side Mount
Figure 10. Side Battery Mount Model
Four one-inch high walls were welded to a base plate. For each of the batteries
two threaded rods and a one-inch wide steel bar were used to bolt them down to
two tabs located on opposite sides and ends of the base plate. In order to keep the
batteries from sliding on the baseplate two adjustable L-shaped walls were bolted
to the center of the plate serving as a barrier between the batteries. Since the
baseplate did not need to be raised it was cut to include two slotted tabs extending
from the left side and two slotted tabs extending from the right side. The four tabs
were aligned with two bars bolted to two parts of the frame located between the
front and back wheels. This entire assembly was then bolted to two pipe supports,
which were rigidly mounted to the kart. The pipes were designed to fit around the
1 inch outer-diameter frame of the kart, and their lengths and angles were
designed to effectively support the rest of the mount.
Detail drawings of the battery mounts are included in Appendix F.
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2.2.6 Motor Mount
Figure 11. Motor Mount Model
The motor mount was first designed to fit the form factor required, attaching to
the kart frame and aligning with the rear axle gearing. After considering weight
distribution, it was decided to mount the motor in the same location as the gas
engine. This proved a challenge, as the motor was larger than the gas engine; the
position had to be carefully calculated to avoid exposing the driver to the chain, or
colliding with the right rear wheel. Taking into account these constraints, the
optimum positioning was found and the motor mount built around it, with
adjustability for fine-tuning alignment and tightening the chain.
The motor mount model was then refined for strength by changing the thickness
of the plate steel used in the construction, and adding gussets to the corners for
added stiffness. Starting with ⅛” steel plate, the loads that the motor mount must
carry were simulated in the PTC Creo Simulate finite element program. The
deformation of the ⅛” was too high to maintain gear alignment, so the design was
strengthened with gussets and 3/16” steel. This only added approximately 4 lbs
to the weight, while significantly decreasing the simulated deformation.
To be sure the design would not fail, a stress analysis was performed, accounting
for motor weight, torque, and inertia during maximum accelerations. The
maximum stress was calculated to be less than the yield stress with a factor of
safety of 2.
Once the structural design was finalized, a chain guard made of 1/16” sheet metal
was designed to completely isolate the chain from the driver, and protect against
potential de-railing of the chain.
Detail drawings of the motor mount are included in Appendix F.
23. 23
2.2.7 Accelerator Transponder
An accelerator transponder was designed in order to tell the motor controller
when a user depressed the accelerator pedal. The controller is able to read voltage
as an input for this function, so a potentiometer was mounted to the kart in such a
way that it could use the existing gas pedal and control cable. The placement of
the potentiometer changed several times while the rest of the components were in
the design phase. The final design placed the potentiometer on the back of the
driver’s seat. It was within range of the control cable, while keeping it out of the
way of any moving components. It was also easily accessible for servicing if
necessary.
The mounting hardware for the potentiometer was designed to be firmly attached
to the seat, but also flexible to distribute some of the stresses applied to the
potentiometer. The potentiometer was screwed onto the mounting hardware at one
end, and a control arm attached to the other end. The control arm was built using a
standard knob with a set screw, and a custom-fabricated piece of aluminum which
was glued to the knob. The control arm reached out two inches from the center of
the potentiometer. At one end, the control cable was attached in the same fashion
as a bicycle’s brake cable. At the other end, a spring connected the system to the
frame of the kart. This spring was designed to keep the potentiometer equilibrium
point at zero, which meant that if the control cable failed while the kart was in
motion, the potentiometer would return to a point that told the controller not to
continue accelerating.
2.3 Use
2.3.1 Data Acquisition
Getting usable data from the Arduino to measure our desired benchmarks has
already been covered in the previous section, but extracting the data was a whole
other issue. The Arduino clone itself has very little usable memory for storage.
The Atmega328 microcontroller on the Arduino board contains only 31.5KB of
flash memory [2], which is not nearly enough room to store the large quantities of
data generated by the sensor. The easiest and most cost effective solution for
extracting the data ended up being output through USB to a laptop.
It was decided that a team member’s laptop would be directly connected to the
Arduino using its USB port. The speed, acceleration, and total distance traveled
by the kart were calculated using the script seen in Appendix D, and were
outputted to the Arduino’s serial monitor. There was no way to save the data
outputted directly to the Arduino software serial monitor, so a third party software
called CoolTerm was used. CoolTerm is a simple serial port terminal application
created by Roger Meier, a programming hobbyist [1]. CoolTerm acts as an
independent serial monitor that allows the outputs of a device’s serial monitor to
24. 24
be saved as a text file. This was extremely useful when benchmarking the kart at
the testing location.
During testing, the driver of the kart was required to wear a backpack with the
laptop in it, which was connected to the Arduino through USB. Before running
any tests a start button must be clicked in the CoolTerm interface. At the end of
the test a stop button must be pressed and then the output of the serial monitor can
be converted to a text file.
In the second semester, we were provided with monitoring and data recording
software that interfaced with the motor controller and gave us a more accurate
data stream of motor RPM, which was used to calculate the speed and distance
traveled to compare to the original kart.
2.3.4 Mathematical Model of Electric kart
The GUI (Graphic User Interface) for the mathematical model is simple and easy
to use. The user selects the voltage and current then inputs the number of teeth of
the motor’s spur gear and the weight of the kart frame and the driver. The user
then clicks the “Update” button, and the model calculates the total weight, gear
ratio, wheel torque, acceleration, & deceleration and displays the results. By
adjusting the parameters, the user can select a configuration that will fulfill the
design requirements.
2.3.5 Battery Mounts
The battery mounts are clamped to the frame with U-clamps. The batteries are
placed in the battery mount tray, and held down with steel plate clamps tightened
by threaded rod.
2.3.6 Motor Mount
The motor mount is bolted to the frame on the same platform as the gas engine.
In order to align and tighten the chain, the bolt connections are slotted for
positioning. The motor slides in from the side and is bolted to the mount at both
ends.
2.3.7 Components Box
The components box contains relays, the battery management system, a current
sensor, and the control switches. These include a key-switch to turn the go-kart
on, a forward/reverse switch, and an emergency stop button. These are located to
the right of the driver seat, within easy access during operation.
25. 25
2.4 Conclusions Drawn from Mathematical Model
Using the results of the model, the design parameters were selected. The motor
spur gear was selected to be a 29-tooth gear. The maximum DC voltage selected
to be 36V using three 12V batteries. The controller current was selected to be
400A. These parameters yield a predicted acceleration which exceeds the gas kart
benchmark, and a wheel torque curve that provides just enough torque to slightly
exceed the static limit, all the way up to a theoretical vehicle speed of 50 mph.
3. Implementation
Figure 12. Front View
3.1 Sourcing Material
The largest pieces of structural material were all designed with 3/16” steel plate,
for overall simplicity. Although we were advised to order our materials online,
we were able to find a local steel yard in Owego, NY which gave us four times as
much steel for half the price, with zero shipping wait time. We also purchased the
support pipes from that steel yard. Our fasteners were sourced from local
hardware stores, and our electronic components and cases from a local electronics
store.
Using local sources saved us shipping costs and time, allowing us to complete our
project ahead of schedule and under-budget.
26. 26
3.2 Hardware Fabrication
Figure 13. Side View
The motor mount and battery mounts were fabricated from steel plate, machined
and welded in the Watson School Student Shop. The electrical components and
control switches were mounted in aluminum boxes, also machined to purpose in
the Student Shop.
In order to fulfill the requirement that we not alter the frame of the cart, all
mounts were connected to the frame with steel U-clamps.
3.3 Wiring
A wiring design was implemented and designed to optimize room for the user, in
addition to making the tedious wiring job easier. It should also be noted that
components that were connected directly to each other were placed closely to
reduce the size of the harness. The harness was built in a laboratory within the
Raymond Plant in Greene NY. The design called for a mixture of gauged wire.
Large gauge wire was run along the frame and besides the seat, as to not interfere
with the driver. Similar tactics were implemented to keep the over 30 sensor wires
out of the way. A components box was designed to keep most of the additional
circuit elements out of view, while also providing a confined space so that
connections between each could be made. The components box contained the
BMS, voltage regulator, main contactor, undervoltage coil relay, two 12V auto
relays, and the rest of our control switches. By inserting all of these components
within our components box the implementation was much easier and it provided a
much sleeker look for our final design.
27. 27
3.4 Accelerator Transponder
The accelerator transponder was fabricated using sheet aluminum in the Student
Shop. It was adhered to the back of the driver’s seat using heavy-duty double-
sided adhesive tape. The control arm was also fabricated from aluminum, and was
epoxied to the knob. The knob and control arm assembly was then epoxied to the
potentiometer. The control cable needed to be elevated from the driver’s seat in
order to place it in the same plane as the control arm. To do this, a block of
aluminum was adhered to the seat with heavy-duty double-sided adhesive tape,
and the control cable was zip-tied to the block.
4. Evaluation
4.1 Testing
Testing is essential in ensuring that the equipment mounted to the kart is secure,
in working order, and fulfills the design requirements described in Section 1.3.
The full list of requirements, and the test procedure that relates to each
requirement, are specified in Appendix B: Project Requirements.
The mechanical and configuration requirements were tested in the lab before the
kart was driven. For example, requirements R-09 and R-11 specify that the
motor and controller provided by Raymond will be used; this is easily confirmed
by inspection.
The electrical properties of the kart were tested to conform to the expected design
parameters, as the kart was being wired up under the supervision of Raymond
Corporation. This portion of the testing was carried out by the electrical
engineering team, at Raymond Corporation’s facility, during the wiring phase of
assembly.
The performance requirements were tested at the airstrip at Tri-Cities Airport in
Endicott, NY. These tests were carried out by the design team, in exactly the
same fashion in both the fall and spring semesters. These included top speed
runs, maximum acceleration and braking runs, and the autocross course to test
handling.
A full list and description of all test procedures is provided in Appendix C: Test
Procedures.
28. 28
4.2 Test Results
4.2.1 30-0 mph Deceleration
Gas Kart: 5.306 seconds, 93.84 feet (average of all runs).
Electric Kart: 2.74 seconds, 39.31 feet (average of all runs)
Figure 12. Average Deceleration Performance of both Gas and Electric Kart
29. 29
4.2.2 Efficiency
Gas Kart: 40.57 miles/gallon
Electric Kart: 50.97 miles/gallon
Wh
4.2.3 Top Speed
Gas Kart: 37.58 mph
Electric Kart: 57.77 mph
Figure 13. Speed Data from Top Speed Runs
30. 30
4.2.4 Weight Distribution
Gas Kart: Total weight: 174 lbs
Gas Go-Kart Weight Distribution, Unladen (lbs)
Left Wheel: Right Wheel: Total Per Axle:
Front Axle: 36 (20.7%) 36 (20.7%) 72 (41.4%)
Rear Axle: 43 (24.7%) 59 (33.9%) 102 (58.6%)
Electric Kart: Total weight: 340 lbs
Electric Go-Kart Weight Distribution, Unladen (lbs)
Left Wheel: Right Wheel: Total Per Axle:
Front Axle: 90 (26.5%) 90 (26.5%) 180 (52.9%)
Rear Axle: 85 (25%) 75 (22%) 160 (47.1%)
4.2.5 0-30 mph Acceleration
Gas Kart: Reached 30 mph at 200 ft and 9.1 seconds (average of all runs).
Electric Kart: Reached 30 mph at 41 ft and 2.94 seconds (average of all
runs).
Figure 14. Average 0-30 mph Performance
31. 31
4.2.6 Autocross Race Times
Gas Kart: Average time: 43.12 seconds.
Best recorded time: 39.87 seconds.
Electric Kart: Average time: 37.23 seconds.
Best recorded time: 34.28 seconds.
4.3 Assessment
The WCP10 team is extremely pleased with the results of our work. We have met
or exceeded every benchmarked requirement, and the mathematical model of the
electric kart made fairly accurate predictions of the actual functioning kart. Our
hard stop deceleration time was almost exactly the same as in the model, whereas
the acceleration and top speed performed slightly better than predicted. Our
autocross time and handling were vastly improved, although there was a possible
margin of error due to having to recreate the course on the uneven slopes of M-
Lot rather than the original flat airport tarmac. Unfortunately, we were unable to
meet our stretch goal of integrating regenerative braking into the system.
Over the past two semesters, the WCP10 team was able to build a speedometer
for benchmarking the gas kart, create a mathematical model of the kart, and use
the model to create a superior electric version. We went through countless design
iterations for each component of the conversion kit, and learned about the process
of bringing a virtual design into the real world. We collaborated and got help from
our advisors to achieve our goals, and as a team, we were able to build a fully
functioning electromechanical system that could drive at nearly 60 miles an hour.
Our team was able to meet our design description of performing a practical
experiment to explore the process of converting a gas powered vehicle to an
electric vehicle, but we were also able to show that electric vehicles can
outperform gasoline vehicles while also being more energy efficient. The WCP10
team thanks Raymond Corporation for its generous sponsorship, as well as their
valuable time in directly assisting with our design and implementation. We would
like to thank the Tri-Cities Airport for allowing us to test at their facility. Finally,
we would like to thank Binghamton University and the Watson Capstone Project
organization for providing us with this opportunity.
32. 32
5. Budgetand Schedule
5.1 Budget
Below is a table outlining the budget for the project. By using all local sources,we were able to
finish our project under-budget by 22%.
Item Original
Estimate $
Actual $ Over/(Under)
Tools 75 45 (30)
Parts 350 263 (87)
Materials 125 120 (5)
Total 550 428 (122)
Budget 550 (122)
Figure 11. Budget Chart
33. 33
5.2 Top-level Schedule
Below is an outline of our schedule where a short description of each task,the percent completed
of each task,and when the task was completed can be seen.
Description Percent Complete Date Completed
Project Launch 100 September 21, 2015
Completed Sensor Design 100 October 9, 2015
Sensor Prototype 100 October 15, 2015
Completed Sensor 100 November 6, 2015
Requirements Analysis for IC Kart
(Data Collection)
100 November 18, 2015
Computer Model & Simulation 100 November 20, 2015
Interim Design Report 100 December 4, 2015
Interim Presentation 100 December 11, 2015
Completed Mounting Design 100 March 15, 2016
Mounting Prototypes 100 March 30, 2016
Operational Electric Kart 100 April 20, 2016
Requirements Analysis for Electric Kart
(Data Collection)
100 April 25, 2016
Delivery to Client 100 April 30, 2016
Final Presentation and Report 50 May 5, 2016
6. Future Plans
The final completed product has been delivered to the client. The project we were tasked with is held each
year by the Raymond Corporation and the kart will be disassembled by them over the summer. Once
disassembled they will convert it back to a gas version and task the project to yet another team of seniors,
who will try and succeed in doing what we did. Though we have little to do with where the project goes
moving forward,we do have to take what we learned this past year with us in our future endeavours. This
project has taught each and every one of us valuable lessons on time management, teamwork, and
research. Each member will go on their separate ways and will look back upon this project as a vital
learning experience that has contributed to the people we are today.
35. 35
Appendix A: ProjectProposal
Watson Capstone Projects
Project Proposal Form
Computer, Electrical, and Mechanical Engineering
2015-2016 Version
1. Project Title
Battery powered go-kart
2. Organization Name and Address
The Raymond Corporation
22 South Canal Street
Greene, NY 13778
3. Contact Names,Phone, Email Address
Sponsor Management Representative: Fernando Goncalves 607-656-2590
fernando.goncalves@raymondcorp.com
Sponsor Technical Representative: Dan Driscall 607-656-2588
Dan.driscall@raymondcorp.commailto:Dan.driscall@raymondcorp.com
4. Project Description
A Go-Kart is a single operator, off-road, purpose built vehicle. The goal of this project is to take
an internal combustion powered vehicle and convert it to an electric powered vehicle, using
components found in an industrial forklift. Students will be expected to take a fully built kart,
baseline it, convert it, then compare the performance to the baseline. A selection of AC induction
motors, controllers, and battery voltages will be provided to the students. The students will be
responsible for selecting the components to best match or exceed the performance of the IC kart,
The students must then design and build the necessary components to modifying the kart to
accept the electrical hardware. The Raymond Corporation will provide the kart, motor, controller,
battery, wire, and control software.
5. Project Requirements
The project will provide the students with experience in system level design, including, but not
limited to component interactions and design compromise. The students will employ motor
theory, mechanical power conversion, and packaging techniques. This will be accomplished
through the following:
The students shall benchmark the kart with the following criteria:
1. Top speed
2. Acceleration: 0-30mph, 1/8mi
3. Braking: 30-0mph
4. Curb weight and balance
5. Auto-cross course
6. Fuel consumption/efficiency
The students shall create a model that allows the user to configure the following components:
1. AC induction motor
2. Motor controller
3. Battery voltage
36. 36
4. Gear ratio
The model shall predict the theoretical performance of the kart.
From this model the students shall pick the components to be added to the kart and choose a gear
ratio.
The students shall modify the kart to accept these new components and make the kart functional.
The students shall measure the performance of the electric go-kart using the criteria from the
benchmark and compare it to the model and the benchmark.
6. Budget
The Raymond Corporation will provide the following components:
- Kart
- Helmet
- AC induction motor
- Motor controller and software
- Batteries
- Wire
- Throttle potentiometer
- Switches
- Contactor
Required purchases:
Raw material for mounting brackets, motor interface, and drive gear ($100-$500)
Mounting hardware ($10 -$100)
8. Deliverables and Meetings
Semester 1:
In the first semester the students will baseline the un-modified kart. In addition to the criteria
mentioned above, important vehicle parameters will need to be measured. The measured
parameters should include tire diameter, rolling resistance, vehicle mass (with and without IC
motor components), braking torque, and tire static and kinetic friction coefficients.
Once the baseline criteria and measured parameters are captured the students will create a
spreadsheet that will model the top speed, vehicle weight, acceleration, and braking profile. This
spreadsheet will consist of the measured parameters plus the gear ratio, motor, motor controller,
and battery voltage parameters. The user should be allowed to pick from a list of several gear
ratios, motor, motor controller and batteries. The motor, motor controller and battery parameters
will be provided by The Raymond Corporation.
The output of the spreadsheet should be compared to the baseline kart. This will allow for the
selection of components to be used in building the electric kart.
Semester 2:
The second semester will require the students to design and fabricate the mounting brackets to
install the electric components onto the kart as well as the wiring to connect the electrical
components together.
Once the kart has been converted the students will measure the performance of the vehicle with
the same criteria as the baseline and compare the results to the spreadsheet and the baseline.
9. Recommended Team Composition (3-5 students)
Mechanical Engr: 2-3 Electrical Engr: 2-3 Computer Engr:
37. 37
Appendix B: ProjectRequirements
Qualification Methods
Demonstration – D
Test -- T
Analysis -- A
Inspection -- I
Special (i.e., none of the above) -- S
Requirement
ID # Description Source Value
Qualification
Method Test
Pass/
Fail Comments
Mechanical
WCP10-R-01
The electric go-kart shall meet safety
standards as outlinedin the ASTM
F2007-06 go-kart standards
Watson School,
RaymondCorp N/A I WCP10-T-01
WCP10-R-02
The electric motor's mounting
hardware shall not cause damage to
the existingframe RaymondCorp N/A I WCP10-T-02
WCP10-R-03
The electric motor's mounting
hardware shall use only existing
holes in the frame RaymondCorp N/A I WCP10-T-03
WCP10-R-04
The batteries shall be securely
mountedtothe frame ofthe go-kart Project Team N/A I WCP10-T-04
WCP10-R-05
The 30-0mph brakingdistance and
time of the electricgo-kart shall be
comparable to thegas benchmark RaymondCorp
Within 20%
(ft, sec) T WCP10-T-05
Electrical
WCP10-R-06
All electrical wiringwill be carried
out under RaymondCorp electrical
engineeringsupervision, at the
RaymondCorp facilityin Greene. RaymondCorp N/A I WCP10-T-06
WCP10-R-07
A mathematical model shall be
createdto predict the performanceof
the electric go-kart
Watson School,
RaymondCorp N/A D WCP10-T-07
WCP10-R-08
The electric motor,controller,
voltage andgear ratio shall be
selectedaccordingtothe results of
the model RaymondCorp N/A D WCP10-T-08
WCP10-R-09
The electric go-kart shall be use the
Curtis Model 1236 motor controller
suppliedby RaymondCorp RaymondCorp N/A I WCP10-T-09
WCP10-R-10
The electric go-kart shouldbe at
least as efficient as the gas powered Watson School
Within 15%
(miles/GGE) T WCP10-T-10
WCP10-R-11
The electric motor shall be the model
providedby RaymondCorp RaymondCorp N/A I WCP10-T-11
WCP10-R-12
The electric motor shall be powered
by at least its minimumoperating
voltage RaymondCorp
At least 24
Volts T WCP10-T-12
WCP10-R-13
The kart shall be poweredby no less
than 2 andno morethan3 12V
Batteries suppliedby RaymondCorp RaymondCorp N/A I WCP10-T-13
38. 38
WCP10-R-14
The topspeedofthe electric kart
shall meet or exceedthe
benchmarkedspeedof the gas kart RaymondCorp
At least
benchmark
value T WCP10-T-14
WCP10-R-15
The weight distributionof the
electric kart shouldmatch that of the
gas kart Project Team within 20% T WCP10-T-15
WCP10-R-16
The go-kart shall accelerate from 0-
30mph within 1/8ofa mile RaymondCorp N/A T WCP10-T-16
Miscellaneous
WCP10-R-17
The time aroundthe autocross course
shall be comparable tothat of thegas
poweredkart Watson School
within 20%
(seconds) T WCP10-T-17
WCP10-R-18
The go-kart shouldimplement
regenerative braking Project Team N/A D WCP10-T-18
WCP10-R-19
The distance traveledby thego-kart
shall be measuredandthe data stored
using an Arduino kit Project Team Distance (ft) T WCP10-T-19
WCP10-R-20
The speedof the go-kart shall be
measuredandthe data storedusing
an Arduino kit Project Team
Velocity
(mph) T WCP10-T-20
WCP10-R-21
The acceleration ofthe go-kart shall
be measuredandthe data stored
using an Arduino kit Project Team
Acceleration
(ft/s^2) T WCP10-T-21
WCP10-R-22
The budget for this project shall not
exceed$550 ($110perteam
member) Watson School N/A I WCP10-T-22
Requirements: Detail Description
WCP10-R-01
The electric go-kart shall meet safety standards as outlined in the ASTM F2007-06 go-kart
standards.
1.1 The electric go-kart shall not be modified in any way that violates safety standards.
WCP10-R-02
The electric motor's mounting hardware shall not cause damage to the existing frame.
2.1 The mounting hardware shall not interfere with existing parts on the go kart.
2.1.1 Mounting hardware shall be custom designed to achieve this goal
WCP10-R-03
The electric motor's mounting hardware shall use only existing holes in the frame.
WCP10-R-04
The batteries shall be securely mounted to the frame of the go-kart.
4.1 The mount shall not interfere with existing and added pieces of hardware.
4.2 The mount should be positioned to fulfill the requirements for weight distribution.
WCP10-R-05
The 30-0mph braking distance and time of the electric go-kart shall be comparable to the gas
benchmark.
WCP10-R-06
All electrical wiring shall be carried out under Raymond Corp electrical engineering supervision,
at the Raymond Corp facility in Greene.
39. 39
WCP10-R-07
A mathematical model shall be created to predict the performance of the electric go-kart.
7.1 The model shall be created using the Matlab programming tool.
7.2 The model shall use benchmark data from the gas configuration.
7.2.1 The data shall be collected using sensors connected to the go-kart.
WCP10-R-08
The electric motor, motor controller, voltage and gear ratio shall be selected according to the
results of the model.
WCP10-R-09
The electric go-kart shall use the Curtis Model 1236 motor controller supplied by Raymond Corp.
WCP10-R-10
The electric powered kart shall be as efficient as the gas powered go-kart
10.1 The efficiency for the gas configuration shall be calculated by measuring the amount
of fuel used per distance traveled.
10.2 The efficiency for the electric configuration shall be calculated by measuring
electric power consumption per distance traveled and converting to Gas Gallon
Equivalent (1 GGE = 33.4 kWh).
WCP10-R-11
The electric motor shall be the model provided by Raymond Corp.
WCP10-R-12
The electric motor shall be powered by at least its minimum specified operating voltage.
WCP10-R-13
The go-kart shall be powered by no less than 2 and no more than 3 12V Batteries supplied by
Raymond Corp.
10.1 The number of batteries used shall be determined using data from the mathematical
model.
WCP10-R-14
The top speed of the electric go-kart shall meet or exceed the benchmarked speed of the gas kart.
WCP10-R-15
The weight distribution of the electric go-kart should match that of the gas kart.
15.1 The added weight of the electric motor,mounting harness and battery shall be
considered when determining weight distribution
WCP10-R-16
The go-kart shall accelerate from 0-30mph within 1/8 of a mile.
WCP10-R-17
The electric go-kart shall complete the autocross course in a comparable time to the gas powered
kart.
17.1 The time taken for the electric go-kart to complete the autocross course shall be
within at least 20% of the gas powered kart’s time.
WCP10-R-18
The go-kart should implement regenerative braking.
WCP10-R-19
The distance traveled by the go-kart shall be measured and the data stored using an Arduino kit
WCP10-R-20
The speed of the go-kart shall be measured and the data stored using an Arduino kit.
WCP10-R-21
The acceleration of the go-kart shall be measured and the data stored using an Arduino kit.
40. 40
WCP10-R-22
The budget for this project shall not exceed $550 ($110 per team member).
22.1 The budget shall be monitored throughout the project timeline and all purchases
shall be documented
Appendix C: TestProcedures
WCP10-T-01-I
Requirements tested:
R-01 - “The electric go-kart shall meet safety standards as outlined in the ASTM F2007-06 go-kart
standards”
Equipment
● All structural and drive-related components
Procedure (Inspection)
The WCP10 team member will visually inspect the kart to ensure all hardware is secure and no
structural failures are present. Each part of the ASTM safety standards will be inspected in this
way.
Component inspected: Inspection result:
Structural/hardware Pass
Electric insulation Pass
Miscellaneous
components
Pass
WCP10-T-02-I
Requirements tested:
R-02: “The electric motor's mounting hardware shall not cause damage to the existing frame”
R-03: “The electric motor's mounting hardware shall use only existing holes in the frame”
Procedure (Inspection)
The team member inspects the frame of the kart to ensure no damage has been inflicted. This is
done each time a new hardware component is attached to the kart.
41. 41
WCP10-T-04-I
Requirements tested:
R-04: “The batteries shall be securely mounted to the frame of the go-kart”
Equipment
● All battery mounting hardware,custom and standard.
Procedure (Inspection)
The team member will perform non-destructive testing on the mounted batteries. The team
member will first visually inspect the mounted batteries, then he will apply force to them,
checking for abnormal deflection or any mechanical failure.
Battery # Visual inspection result NDT result
1 Pass Pass
2 Pass Pass
3 Pass Pass
WCP10-T-05-T
Requirements tested:
R-05: “The 30-0mph braking distance and time of the electric go-kart shall be comparable to the gas
benchmark”
Equipment
● Speedometer
● Laptop with Data Recording Software
● Distance measuring roller
Procedure (Test)
The team member will set up the speedometer and data recording device. He will then accelerate
the kart to the desired speed, and brake. The time and distance of the braking test are recorded on
the data recording device.
Average Time to Stop Average Distance to Stop
Electric 2.7 sec 39.3 ft
Gas 5.3 sec 93.8 ft
42. 42
WCP10-T-06-I
Requirements tested:
R-06: “All electrical wiring will be carried out under Raymond Corp. electrical engineering supervision,at
the Raymond Corp facility in Greene.”
Equipment
● Multimeter
● Soldering equipment
● Crimping equipment
● Controller programming interface
Procedure (Inspection)
The circuit and cable routing designed by the electrical engineering team is assembled and tested
at the Raymond Corporation facility in Greene, under supervision of Raymond electrical
engineering staff. The circuitry is inspected by the team, then by the Raymond supervisor. The
kart is placed on a stand before the batteries are connected, and the functionality tested on the
stand with the wheels in the air before being approved: the accelerator pedalis depressed and the
rear wheels spun, then stopped with the brakes; the reverse switch is flipped and the wheels spun
again; and the emergency stop button and keyswitch are tested.
Inspection Inspected by:
Circuitry - BU Team Chase Bouchard
Circuitry - Raymond supervisor Dan Driscall
Functionality Pass
43. 43
WCP10-T-07-D
Requirements tested:
R-07: “A mathematical model shall be created to predict the performance of the electric go-kart”
R-08: “The electric motor, controller, voltage and gear ratio shall be selected according to the results of the
model”
Equipment:
● MATLAB programming software
Procedure (Demonstration)
The team member demonstrates the mathematical model created in the Fall semester.
WCP10-T-09-I
Requirements tested:
R-09: “The electric go-kart shall be use the Curtis Model 1236 motor controller supplied by Raymond
Corp”
R-11: “The electric motor shall be the model provided by Raymond Corp”
Equipment:
● Curtis Model 1236 motor controller
● Electric motor provided by Raymond corp
Procedure (Inspection)
The team member will visually inspect that the motor controller being used is the Curtis Model
1236 motor controller. He then inspects the motor to make sure that the motor is, in fact,the motor
that Raymond corp provided.
44. 44
WCP10-T-10-T
Requirements tested:
R-10: “The electric go-kart should be at least as efficient as the gas powered kart”
Equipment
● Data recording device
Procedure (Test)
The current used by the motor is monitored via the motor controller, simultaneously with the
motor RPMs,which are converted to distance traveled and total energy by integration. The
efficiency is converted into equivalent miles per gallon.
Total distance Energy Used Efficiency
0.357 miles 881 BTU
or
0.0077 gas gallon equivalent
50 mpg
WCP10-T-12-T
Requirements tested:
R-12: “The electric motor shall be powered by at least its minimum operating voltage”
R-13: “The cart shall be powered by no less than 2 and no more than 3 12V Batteries supplied by Raymond
Corp”
Equipment
○ Electric motor
○ Lithium ion batteries
○ Multimeter
Procedure (Test and Inspection)
The team member checks the batteries connected to the motor. There must be at least two batteries
connected in series to the motor to provide it with its minimum operating voltage. If there are at
least two batteries connected,the test passes. There can be no more than three batteries connected
in series at once. If there are a maximum of three batteries attached in series to the motor, the test
passes. The voltage across all batteries is tested with the multimeter, and must be no more than
36V.
45. 45
WCP10-T-14-T
Requirements tested:
R-14: “The top speed of the electric cart shall meet or exceed the benchmarked speed of the gas cart”
Equipment
● Speedometer
● Laptop
Procedure (Test)
The gas kart is benchmarked before the conversion, during the gas kart testing at the Tri-Cities
airport in the fall semester. Each team member activates the recording program on the laptop,
performs two top-speed runs down the taxi lane of the airport, and then saves the results on the
laptop. In the spring semester,the test is repeated for each team member during the electric kart
testing at the Tri-Cities airport. The top speeds recorded are averaged across the team for each
kart configuration and compared.
Configuration Top Speed
Internal Combustion 36.7 mph
Electric 57.8 mph
WCP10-T-15-T
Requirements tested:
R-15: “The weight distribution of the electric kart should match that of the gas kart”
Equipment
● Go-kart
● Scales
Procedure (Test)
The team member places the kart on the weight scales (one scale under each tire) in order to weigh
the reaction force on each tire. The results are then compared to the results of the gas-kart weight
distribution.
Tire Weight (Gas) Weight (Electric)
Front Left 36 lbs (20.6%) 90 lbs (26.5%)
Front Right 36 lbs (20.6%) 90 lbs (26.5%)
Rear Left 43 lbs (24.7%) 85 lbs (25%)
Rear Right 59 lbs (33.9%) 75 lbs (22%)
Total 174 lbs 340 lbs
46. 46
WCP10-T-16-T
Requirements tested:
R-16: “The go-kart shall accelerate from 0-30mph within 1/8 of a mile”
Equipment
● Data recording device
Procedure (Test)
The team member sets up the data-recording device. He then drives the kart from rest to 30mph,
then decelerates at a safe rate and brings the kart to a stop again. The data is then saved for
analysis.
Time to 30mph Distance to 30mph
Electric Kart 2.94 sec 41 ft
Gas Kart 9.10 sec 200 ft
WCP10-T-17-T
Requirements tested:
R-17: “The time around the autocross course shallbe comparable to that of the gas powered kart”
Equipment
● Stopwatch
Procedure (Test)
Each team member drives the autocross course two times, while another team member uses the
stopwatch to time them. The times are averaged. The test is performed first on the gas
configuration, and the on the electric configuration. The gas and electric runs of each driver are
compared
Gas Time Electric Time
Average 43 sec 37 sec
Best 39.8 sec 34.5 sec
47. 47
WCP10-T-18-D
Requirements tested:
R-18: “The go-kart should implement regenerative braking”
Equipment
● Speedometer
● Laptop
Procedure (Demonstration)
If regenerative braking is enabled, each driver performs two 15-to-0 mph runs with regenerative
braking only. The data recording program is enabled on the laptop before each run, and the data is
used to calculate the average deceleration of the kart with regenerative braking. If possible, the
charge of the batteries is also recorded to verify that electric braking does recharge the batteries.
WCP10-T-19-T
Requirements tested:
R-19: “The distance traveled by the go-kart shall be measured and the data stored using an Arduino kit”
R-20: “The speed of the go-kart shall be measured and the data stored using an Arduino kit”
R-21: “The acceleration of the go-kart shall be measured and the data stored using an Arduino kit”
Equipment
● Data recording device
Procedure (Test)
The team member activates the data recording device at the beginning of each test run. The
software automatically records distance, acceleration, and speed data. The team member saves the
data to a flash drive after each test.
WCP10-T-22-I
Requirements tested:
R-22: “The budget for this project shall not exceed $550”
Equipment
● N/A
Procedure (Inspection)
The budget is shown to be within its bounds at the end of the project.
48. 48
Appendix D: Code used for Speedometer& Storing Data
The code below was written in the Arduino coding platform. The syntax and format of code written in this
platformis similar to the C/C++ coding languages.
#include <LiquidCrystal.h> //allow us to use commands for lcd display
//initilize the library with the numbers of the attached pin
LiquidCrystal lcd(7,8,9,10,11,12);
const int hallPin = 2; //hall effect sensor is connected to pin 2
const unsigned long sampleTime = 250; //determine how long we want to take data
const float diameter = 10.5; //diameter of wheel
const float circumference = diameter*3.14159;
const float DistperRevFt = circumference/12;
const int magnets = 6; //number of magnets on axle
float distance; //distance traveled
float tempfps;
float temptime;
float rev; //number of revolutions of wheel
float begintime = 0;
float timetothirty = 0;
void setup()
{
lcd.clear();
delay(1000);
int count = 0;
pinMode(hallPin,INPUT); //set pin as input
Serial.begin(9600); //initialize the baud rate of the serial monitor
lcd.begin(16,2); //set up the LCD's rows and columns
lcd.print("Hello Team");
delay(2000);
lcd.clear(); //clear the LCD
}
void loop()
{
float mile = DistperRevFt/5280;
int kount=0;
float temprev = 0;
boolean kflag=LOW;
unsigned long currentTime=0;
unsigned long startTime=millis();
while (currentTime<=sampleTime)
{
if (digitalRead(hallPin)==HIGH)
51. 51
Appendix E: Code used to Build Model
function varargout = WCP10_MathModel(varargin)
% WCP10_MATHMODELMATLAB code for WCP10_MathModel.fig
% WCP10_MATHMODEL, by itself, creates a newWCP10_MATHMODELor raises the existing
% singleton*.
%
% H = WCP10_MATHMODELreturns thehandle to a newWCP10_MATHMODEL orthe handle to
% the existingsingleton*.
%
% WCP10_MATHMODEL('CALLBACK',hObject,eventData,handles,...)calls the local
% functionnamedCALLBACK in WCP10_MATHMODEL.Mwith thegiven input arguments.
%
% WCP10_MATHMODEL('Property','Value',...) creates a newWCP10_MATHMODELor raises the
% existingsingleton*. Startingfromthe left,propertyvalue pairs are
% appliedto the GUI before WCP10_MathModel_OpeningFcn gets called. An
% unrecognizedpropertyname or invalidvalue makes propertyapplication
% stop. All inputs are passedtoWCP10_MathModel_OpeningFcnvia varargin.
%
% *See GUI Options onGUIDE's Tools menu. Choose"GUI allows only one
% instance to run (singleton)".
%
% See also: GUIDE, GUIDATA,GUIHANDLES
% Edit the above text tomodifythe response tohelpWCP10_MathModel
% Last Modifiedby GUIDE v2.502-Dec-2015 16:46:04
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', @WCP10_MathModel_OpeningFcn, ...
'gui_OutputFcn', @WCP10_MathModel_OutputFcn,...
'gui_LayoutFcn', [] , ...
'gui_Callback', []);
if nargin && ischar(varargin{1})
gui_State.gui_Callback = str2func(varargin{1});
end
if nargout
[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
52. 52
gui_mainfcn(gui_State, varargin{:});
end
% Endinitializationcode - DO NOT EDIT
% --- Executes just beforeWCP10_MathModel is made visible.
function WCP10_MathModel_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has nooutput args, see OutputFcn.
% hObject handle tofigure
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% varargin commandline arguments toWCP10_MathModel (see VARARGIN)
movegui(hObject,'center')
Read In Torque Curves
filename = 'Motor1__15V-Limits-torque-rpm.xls';
sheet = 'U-D';
handles.T_200A = xlsread(filename,sheet,'P7:R13');
handles.T_300A = xlsread(filename,sheet,'L7:N13');
handles.T_400A = xlsread(filename,sheet,'H7:J13');
handles.T_500A = xlsread(filename,sheet,'D7:F12');
% Rows are data points,columns are: 1 - Torque (Nm), 2 - Voltage,3 - RPM
Add RPM column to each curve for 36V & convert from Nm to ftlbs
% 200A
handles.T_200A(:,4) = handles.T_200A(:,3)* 36/24;
handles.T_200A(:,1) = handles.T_200A(:,1)* 0.737562149277;
% 300A
handles.T_300A(:,4) = handles.T_300A(:,3)* 36/24;
handles.T_300A(:,1) = handles.T_300A(:,1)* 0.737562149277;
% 400A
handles.T_400A(:,4) = handles.T_400A(:,3)* 36/24;
handles.T_400A(:,1) = handles.T_400A(:,1)* 0.737562149277;
% 500A
handles.T_500A(:,4) = handles.T_500A(:,3)* 36/24;
handles.T_500A(:,1) = handles.T_500A(:,1)* 0.737562149277;
Read in Benchmark Data
handles.bench0_30= xlsread('BenchmarkData.xlsx',2,'X4:Y37','basic');
handles.bench30_0= xlsread('BenchmarkData.xlsx',1,'X4:Y23','basic');
Update Figures & Values
53. 53
re-calculates accelerations, velocities and torques re-plots velocity/time(s) and wheeltorque/rpm
update(handles);
% Choose default commandline output forWCP10_MathModel
handles.output = hObject;
% Update handles structure
guidata(hObject,handles);
% UIWAIT makes WCP10_MathModel wait for user response(see UIRESUME)
% uiwait(handles.figure1);
% --- Outputs fromthis functionare returnedtothe commandline.
function varargout = WCP10_MathModel_OutputFcn(hObject, eventdata,handles)
% varargout cell array for returningoutput args (see VARARGOUT);
% hObject handle tofigure
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Get default commandline output fromhandles structure
varargout{1} = handles.output;
% --- Executes on selectionchange in current.
function current_Callback(hObject, eventdata, handles)
% hObject handle tocurrent (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
Set Current to SelectedValue
contents = cellstr(get(hObject,'String'));
handles.I = str2double(contents{get(hObject,'Value')});
% Hints: contents = cellstr(get(hObject,'String')) returns current contents as cell array
% contents{get(hObject,'Value')} returns selecteditemfromcurrent
% --- Executes duringobject creation,after settingall properties.
function current_CreateFcn(hObject, eventdata, handles)
% hObject handle to current (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
54. 54
Set Current to SelectedValue
contents = cellstr(get(hObject,'String'));
handles.I = str2double(contents{get(hObject,'Value')});
% Hint: popupmenucontrols usually have a white backgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
function motor_teeth_Callback(hObject, eventdata,handles)
% hObject handle tomotor_teeth (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of motor_teethas text
% str2double(get(hObject,'String')) returns contents of motor_teethas a double
% --- Executes duringobject creation,after settingall properties.
function motor_teeth_CreateFcn(hObject, eventdata,handles)
% hObject handle tomotor_teeth (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
function wheel_teeth_Callback(hObject, eventdata,handles)
% hObject handle towheel_teeth (seeGCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of wheel_teethas text
% str2double(get(hObject,'String')) returns contents of wheel_teethas a double
% --- Executes duringobject creation,after settingall properties.
function wheel_teeth_CreateFcn(hObject, eventdata,handles)
% hObject handle towheel_teeth (seeGCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
55. 55
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
% --- Executes on button press in V_24.
function V_24_Callback(hObject,eventdata,handles)
% hObject handle toV_24 (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
handles.V= 24;
set(handles.wt_batteries,'String', '60');
% Hint: get(hObject,'Value') returns toggle state of V_24
% --- Executes on button press in V_36.
function V_36_Callback(hObject,eventdata,handles)
% hObject handle toV_36 (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
handles.V= 36;
set(handles.wt_batteries,'String','90')
% Hint: get(hObject,'Value') returns toggle state of V_36
function wt_frame_Callback(hObject,eventdata, handles)
% hObject handle towt_frame (see GCBO)
% eventdata reserved- tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of wt_frameas text
% str2double(get(hObject,'String')) returns contents of wt_frame as a double
% --- Executes duringobject creation,after settingall properties.
function wt_frame_CreateFcn(hObject,eventdata, handles)
% hObject handle towt_frame (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
56. 56
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
function wt_driver_Callback(hObject, eventdata,handles)
% hObject handle towt_driver (seeGCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of wt_driveras text
% str2double(get(hObject,'String')) returns contents of wt_driveras a double
% --- Executes duringobject creation,after settingall properties.
function wt_driver_CreateFcn(hObject, eventdata, handles)
% hObject handle towt_driver (seeGCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
function wt_batteries_Callback(hObject, eventdata, handles)
% hObject handle towt_batteries (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of wt_batteries as text
% str2double(get(hObject,'String')) returns contents of wt_batteries as a double
% --- Executes duringobject creation,after settingall properties.
function wt_batteries_CreateFcn(hObject, eventdata, handles)
% hObject handle towt_batteries (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
57. 57
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','gray');
end
function wt_total_Callback(hObject,eventdata, handles)
% hObject handle towt_total (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of wt_total as text
% str2double(get(hObject,'String')) returns contents of wt_total as a double
% --- Executes duringobject creation,after settingall properties.
function wt_total_CreateFcn(hObject,eventdata, handles)
% hObject handle towt_total (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'),get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','gray');
end
function update(handles)
% recalculates andreplots velocity/time andtorque/rpm
Update Weight Frame
framewt = str2num(get(handles.wt_frame,'String'));
driverwt = str2num(get(handles.wt_driver,'String'));
battswt = str2num(get(handles.wt_batteries,'String'));
totalwt = framewt + driverwt + battswt;
set(handles.wt_total,'String',num2str(totalwt));
Read Values
contents = cellstr(get(handles.current,'String'));
handles.I = str2double(contents{get(handles.current,'Value')});
I = handles.I;
if I == 200
Tmotor = handles.T_200A;
elseif I == 300
Tmotor = handles.T_300A;
elseif I == 400
58. 58
Tmotor = handles.T_400A;
elseif I == 500
Tmotor = handles.T_500A;
end
if get(handles.V_24,'Value')
Tmotor = [Tmotor(:,3),Tmotor(:,1)]; % col 1: RPMcol2: torque
elseif get(handles.V_36,'Value')
Tmotor = [Tmotor(:,4),Tmotor(:,1)];
end
Calculate Wheel Torque / RPM
percent_wt_rear= 0.6; % fractionof total weight restingonrear axle
% (from empirical measurements)
C_friction= 35 / 0.875/2 / 102; % Coef.of friction;
% slip torque / radius / rear axle weight
max_torque = totalwt * percent_wt_rear * C_friction;% Max torque before slipping[ft-lb]
% calculate mechanical advantage fromgear tooth ratio
mech_adv = str2num(get(handles.wheel_teeth,'String')) / ...
str2num(get(handles.motor_teeth,'String'));
set(handles.gear_ratio,'String',num2str(mech_adv));
% Calculate wheel torque
mRPM = Tmotor(:,1); % motor RPM
wRPM = mRPM / mech_adv;
wheel_diameter= 0.875;% diameter in feet
Vwheel = wRPM * 1000 / 60 * wheel_diameter*pi; % linear velocity at given RPMs [ft/s]
Twheel = Tmotor(:,2).* mech_adv;
fps_to_mph= 3600/5280; % conversionfactor to mphfrom fps
% Plot wheel torque
ax1 = handles.axes1;
plot(ax1,Vwheel*fps_to_mph,Twheel,Vwheel,max_torque*ones(1,length(Vwheel)))
title(ax1,'Wheel Torque')
xlabel(ax1,'Speed(MPH)')
ylabel(ax1,'Torque (foot-pounds)')
legend(ax1,'AppliedTorque','Slip Torque','Location','eastoutside')
Calculate Acceleration & Velocity from Wheel Torque
wheel_diameter= 0.875;% diameter in feet
r = wheel_diameter/2; % radius in feet
Twheel(Twheel>max_torque) = max_torque; % assume no slip
Fwheel = Twheel / r; % [lbs]
59. 59
mass = totalwt / 32.174; % weight / accel due to gravity= mass
% [ lb*sec^2/ft ]
Calculate rolling resistance deceleration
coastTime= 18.02983284; % [sec]
coastDeltaV= 15/fps_to_mph; % [fps]
dec_RR = coastDeltaV/ coastTime; % [ft/s^2]
Numerical iteration to calculate velocity/time for 0-30mph acceleration
iter = 1;
spd= 0; % [ft/sec]
topspd= 30 * 5280 / 3600; % 30 mph convertedtoft/s
step = 1; % time interval [sec]
t(1) = 0; % time [sec]
while (spd(iter) < topspd)&& (iter< 10000)
F = interp1(Vwheel,Fwheel,spd(iter)); % [lb]
A = F / mass - dec_RR; % [ft/s^2]
spd(iter + 1) = spd(iter) + A*step;
t(iter+1)= t(iter) + step;
iter = iter + 1;
end
if iter == 1000
disp('zero to thirtyfail') % if iterative process doesn't reach30mph
end
% Plot 0-30
ax2 = handles.axes2;
plot(ax2,t,spd*fps_to_mph,handles.bench0_30(:,1),handles.bench0_30(:,2),'o')
title(ax2,'Zero-to-30MPH Acceleration')
xlabel(ax2,'Time (seconds)')
ylabel(ax2,'Speed(MPH)')
legend(ax2,'Predicted(EV)','Benchmark(Gas)','Location','eastoutside')
Calculate 30-0
Assumption: Max braking without slipping (max torque applied to wheels)
F = max_torque / r; % [lbs]
A = -F / mass; % [ft/s^2]
deltaV= -30/fps_to_mph; % change in speed[ft/s]
t = deltaV/A; % [seconds]
% Plot 30-0
ax3 = handles.axes3;
plot(ax3,[0t],[300],handles.bench30_0(:,1),handles.bench30_0(:,2),'o')
title(ax3,'30-to-ZeroMPH HardBrakeDeceleration')
xlabel(ax3,'Time (seconds)')
60. 60
ylabel(ax3,'Speed(MPH)')
legend(ax3,'Predicted(EV)','Benchmark(Gas)','location','eastoutside')
function gear_ratio_Callback(hObject, eventdata, handles)
% hObject handle togear_ratio(see GCBO)
% eventdata reserved- tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of gear_ratioas text
% str2double(get(hObject,'String')) returns contents of gear_ratio as a double
% --- Executes duringobject creation,after settingall properties.
function gear_ratio_CreateFcn(hObject, eventdata, handles)
61. 61
% hObject handle togear_ratio(see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles empty - handles not createduntil afterall CreateFcns called
% Hint: edit controls usually have a whitebackgroundon Windows.
% See ISPC andCOMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
% --- Executes on button press in updatebutton.
function updatebutton_Callback(hObject,eventdata,handles)
% hObject handle toupdatebutton (see GCBO)
% eventdata reserved - tobe definedin a future versionof MATLAB
% handles structure with handles anduser data (see GUIDATA)
update(handles);
Published with MATLAB® R2015a
