Team 10: The Calvin Bolt
Final Report
Laura Boluyt
Daniel DeVries
Christine De Zeeuw
Vincent Rovedatti
Engineering 340 Senior Design Project
10 May 2016
2016 © Team 10 and Calvin College
Executive Summary
Calvin College’s Engineering Program culminates in a year-long senior design project, integrating
a Christian faith into the engineering design process. Christian perspectives factor into the decision
making process of design as well as traditional engineering design norms.
Team 10 is the senior engineering design team responsible for the Calvin Bolt. The team consists
of two mechanical and two electrical engineers. The Calvin Bolt will be designed as a four person
electric vehicle that will be used for transportation across Calvin’s campus.
The Calvin Bolt is an electrically powered vehicle with an aluminum frame to provide a larger
vehicle while still maintaining a low overall weight. The larger frame design allows for a more
spacious interior of the vehicle, which also incorporates power front seats to provide maximum
driving comfort for the driver. Suicide doors allow the passengers to enter and exit the vehicle
more freely, increasing the accessibility of the vehicle. The Calvin Bolt also features an electronic
dashboard, providing useful information such as speed of the vehicle and a map of Calvin’s
campus.
The conclusion of the Project Proposal and Feasibility Study determined that the construction of a
fully functional prototype was feasible. After completing the construction of the prototype and
testing the Calvin Bolt successfully met the team’s requirements, providing a vehicle that is safe
and comfortable for the passenger.
Table of Contents
Table of Contents ........................................................................................................................................... i
Table of Figures ............................................................................................................................................ v
Table of Tables ........................................................................................................................................... vii
1 Introduction ................................................................................................................................................ 1
1.1 Calvin College Engineering ....................................................................................................... 1
1.1.1 Senior Design Course ................................................................................................ 1
1.2 The Team ................................................................................................................................... 1
1.2.1 Laura Boluyt .............................................................................................................. 2
1.2.2 Vincent Rovedatti ...................................................................................................... 2
1.2.3 Christine De Zeeuw ................................................................................................... 2
1.2.4 Daniel DeVries .......................................................................................................... 2
1.3 Project Definition ....................................................................................................................... 3
1.3.1 Safety ......................................................................................................................... 3
1.3.2 Ease of Use ................................................................................................................ 3
1.3.3 Quality ....................................................................................................................... 3
1.3.4 Maintenance ............................................................................................................... 3
1.3.5 Aesthetics ................................................................................................................... 3
1.3.6 Seasonal Outdoor Usage ............................................................................................ 4
1.4 Motivation .................................................................................................................................. 4
1.5 Customer .................................................................................................................................... 4
1.6 Design Norms ............................................................................................................................ 5
2 Requirements ............................................................................................................................................. 6
2.1 Functionality .............................................................................................................................. 6
2.2 Capacity ..................................................................................................................................... 6
2.3 Speed.......................................................................................................................................... 6
2.4 Safety ......................................................................................................................................... 6
2.5 Time feasibility .......................................................................................................................... 6
2.6 Budget ........................................................................................................................................ 6
2.7 Project Deliverables ................................................................................................................... 6
3 Project Management .................................................................................................................................. 7
3.1 Project Breakdown .................................................................................................................... 7
3.1.1 Dashboard ................................................................................................................. 7
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3.1.2 Braking System .......................................................................................................... 7
3.1.3 Steering ...................................................................................................................... 7
3.1.4 Motor ......................................................................................................................... 7
3.1.5 Frame Design ............................................................................................................. 7
3.2 Schedule ..................................................................................................................................... 8
3.2.1 Team Meetings .......................................................................................................... 8
3.3 Budget ....................................................................................................................................... 8
3.4 Team Roles ................................................................................................................................ 9
4 Design Alternatives and Decisions .......................................................................................................... 10
4.1 Electronic Dashboard ............................................................................................................... 10
4.1.1 Requirements ........................................................................................................... 10
4.1.2 Data Processor ......................................................................................................... 10
4.1.3 Touchscreen ............................................................................................................. 11
4.1.4 Features .................................................................................................................... 12
4.1.5 Sensors ..................................................................................................................... 12
4.1.6 Data Communication ............................................................................................... 13
4.1.7 Power ....................................................................................................................... 14
4.1.8 Operating Specifications .......................................................................................... 14
4.1.9 Case.......................................................................................................................... 15
4.1.10 Final Design ........................................................................................................... 18
4.2 Dashboard GUI ........................................................................................................................ 18
4.2.1 Requirements ........................................................................................................... 18
4.2.2 Coding Language ..................................................................................................... 19
4.2.3 System automation .................................................................................................. 19
4.2.4 Layout ...................................................................................................................... 21
4.2.5 Continually Updating GUI ....................................................................................... 21
4.2.6 Final Design ............................................................................................................. 21
4.3 Brakes ...................................................................................................................................... 23
4.4 Steering .................................................................................................................................... 24
4.5 Electric Motor and Controller .................................................................................................. 25
4.5.1 Requirements ........................................................................................................... 25
4.5.2 Electric Motor .......................................................................................................... 25
4.5.3 Motor Controller ...................................................................................................... 26
4.5.4 Throttle Potentiometer ............................................................................................. 26
4.5.5 Batteries ................................................................................................................... 27
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4.5.6 Final System configuration ...................................................................................... 27
4.6 Frame Design ........................................................................................................................... 28
4.7 Suspension systems .................................................................................................................. 29
4.7.1 Front suspension and Wheel Brackets ..................................................................... 29
4.7.2 Rear suspension ....................................................................................................... 30
4.8 Seats ......................................................................................................................................... 30
4.9 Doors........................................................................................................................................ 31
4.10 Auxiliary Electrical System ................................................................................................... 32
4.10.1 Requirements ......................................................................................................... 32
4.10.2 DC to DC Converter .............................................................................................. 32
4.10.3 Front and rear lights ............................................................................................... 33
4.10.4 Turn signal system ................................................................................................. 33
4.10.5 Brake light.............................................................................................................. 34
4.10.6 Power Seat Motor .................................................................................................. 34
4.10.7 Final Design ........................................................................................................... 34
5 Prototype Construction ............................................................................................................................ 35
5.1 Electrical System ..................................................................................................................... 35
5.1.1 Cabling ..................................................................................................................... 35
5.1.2 Dashboard Integration.............................................................................................. 35
5.1.3 Vehicle Integration................................................................................................... 36
5.2 Electronic Dashboard ............................................................................................................... 37
5.2.1 Case Assembly ......................................................................................................... 37
5.2.2 Sensor Package ........................................................................................................ 39
5.2.3 Vehicle Integration................................................................................................... 39
5.3 Prototype Construction ............................................................................................................ 41
5.4 Final Product ............................................................................................................................ 53
5.5 Future Work ............................................................................................................................. 54
5.5.1 Mechanical Future Work ......................................................................................... 54
5.5.2 Electrical Future Work............................................................................................. 54
6 Testing ..................................................................................................................................................... 56
6.1 Electronic Dashboard and GUI ................................................................................................ 56
6.2 Primary Electrical System........................................................................................................ 57
6.3 Full Vehicle.............................................................................................................................. 57
7 Business Plan ........................................................................................................................................... 59
7.1 Market Research ...................................................................................................................... 59
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7.2 Breakeven Analysis ................................................................................................................. 60
8 Conclusion ............................................................................................................................................... 61
8.1 Final Results ............................................................................................................................ 61
8.2 Project Reflection..................................................................................................................... 61
9 Acknowledgements .................................................................................................................................. 63
10 Works Cited ........................................................................................................................................... 64
11 References .............................................................................................................................................. 66
12 Appendices............................................................................................................................................. 68
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Table of Figures
Figure 1: The Team....................................................................................................................................... 1
Figure 2: Raspberry Pi 7” Touchscreen with Raspberry Pi board in front ................................................. 12
Figure 3: Front Piece of a Touchscreen Case Design ................................................................................. 15
Figure 4: Third Piece of a Touchscreen Case Design ................................................................................. 16
Figure 5: ModMyPi Touchscreen Case and Display Stand Design ............................................................ 16
Figure 6: 3D Printed Touchscreen Case Design ......................................................................................... 17
Figure 7: Final Case Design as seen from the Back (L) and Front (R) ....................................................... 17
Figure 8: Final Circuit Design for the Electronic Dashboard ..................................................................... 18
Figure 9: Instructions for Automatically Logging in to the Raspberry Pi .................................................. 20
Figure 10: Instructions for Automatically Starting the Raspberry Pi X Server .......................................... 20
Figure 11: Instructions for Automatically Running a Python Script .......................................................... 20
Figure 12: Dashboard GUI Process Flow Chart ......................................................................................... 22
Figure 13: Final Design for the Main Dashboard Tab ................................................................................ 22
Figure 14: Final Design for the Calvin Map Tab ........................................................................................ 23
Figure 15: Jake’s Hydraulic Disc Brake Kit ............................................................................................... 23
Figure 16: Front Wheel Support and Brake Design .................................................................................... 24
Figure 17: Rack and Pinion System ............................................................................................................ 24
Figure 18: Mars ME0708 Electric Motor ................................................................................................... 25
Figure 19: Alltrax SPM 48400 Motor Controller ....................................................................................... 26
Figure 20: View of the Broken Lead on the Potentiometer of the Throttle Box......................................... 27
Figure 21: Electric Motor System Schematics ............................................................................................ 28
Figure 22: Original Front Suspension Design............................................................................................. 29
Figure 23: Front Wheel Bracket Design ..................................................................................................... 30
Figure 24: Rear Suspension Design ............................................................................................................ 30
Figure 25: Front Power Seat Design ........................................................................................................... 31
Figure 26: Seat Frame ................................................................................................................................. 31
Figure 27: Dead Bolt Latching Mechanism ................................................................................................ 32
Figure 28: Turn Signal Schematic .............................................................................................................. 33
Figure 29: The Full Schematic for the Calvin Bolt ..................................................................................... 34
Figure 30: The Cut Power Cables for the Electrical Systems ..................................................................... 35
Figure 31: Dashboard Console.................................................................................................................... 36
Figure 32: The Four Batteries Aligned as they would be in the Trunk ...................................................... 36
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Figure 33: Motor Controller Mounting Location ........................................................................................ 37
Figure 34: The Layers of the 3D Printed Touchscreen Case ...................................................................... 37
Figure 35: The Front View of the Assembled Touchscreen Case .............................................................. 38
Figure 36: The Back View of the Assembled Touchscreen Case ............................................................... 38
Figure 37: The Sensor Package ................................................................................................................... 39
Figure 38: Dashboard Console.................................................................................................................... 40
Figure 39: Rear View of Dashboard Console ............................................................................................. 40
Figure 40: Base Frame ................................................................................................................................ 41
Figure 41: Front Suspension Support.......................................................................................................... 41
Figure 42: Rear Suspension Support ........................................................................................................... 42
Figure 43: Setback Day ............................................................................................................................... 42
Figure 44: Front Suspension Support Reattached ....................................................................................... 43
Figure 45: Vertical Circular Tubing Beams ................................................................................................ 43
Figure 46: Rear Suspension and Axle ........................................................................................................ 44
Figure 47: Front A-arm Suspension ............................................................................................................ 44
Figure 48: Complete Front Suspension....................................................................................................... 45
Figure 49: Front Coilover Suspension ........................................................................................................ 45
Figure 50: Front Exterior Design ................................................................................................................ 46
Figure 51: Rear Exterior Design ................................................................................................................. 46
Figure 52: Roof Construction ..................................................................................................................... 47
Figure 53: Frame Transported to Digital Fabrication ................................................................................. 47
Figure 54: Frames for Seats ........................................................................................................................ 48
Figure 55: Calvin Bolt with Panels ............................................................................................................. 48
Figure 56: Calvin Bolt with Seats and Doors ............................................................................................. 49
Figure 57: Addition of Support Beams ....................................................................................................... 49
Figure 58: Completed Steering and Disc Brakes ........................................................................................ 50
Figure 59: The Calvin Bolt before Paint ..................................................................................................... 50
Figure 60: The Calvin Bolt in the Paint Studio ........................................................................................... 51
Figure 61: Battery Box Covers ................................................................................................................... 51
Figure 62: Installation and Detailing .......................................................................................................... 52
Figure 63: Component Installation ............................................................................................................. 52
Figure 64: Final Prototype (Front View) .................................................................................................... 53
Figure 65: Final Prototype (Rear View) ..................................................................................................... 53
Figure 66: A Chart Showing the Speed Readouts Based on Different Modes of Walking ........................ 56
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Table of Tables
Table 1: A comparison of smart tablet devices considered for the electronic dashboard ........................... 10
Table 2: A comparison of the Arduino and Raspberry Pi ........................................................................... 11
Table 3: A comparison of an Adafruit and Parallax GPS unit .................................................................... 13
Table 4: Estimated Fixed and Variable Costs for Production ..................................................................... 59
Table 5: Production Costs Estimates .......................................................................................................... 60
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1 Introduction
1.1 Calvin College Engineering
Calvin College’s Engineering Program is a four-year program that culminates in a senior design project.
Calvin’s Engineering program is designed to have students take engineering courses from all four
concentrations (electrical/computer, mechanical, chemical, and civil/environmental) for the first two
years. The last two years of the program are spent in the student’s chosen concentration with
concentration-specific courses.
1.1.1 Senior Design Course
The Senior Design project is split between the ENGR 339 and ENGR 340 courses, taken in the fall and
spring semesters respectively. The Senior Design project is 6 credit hours in total and serves as the senior
capstone class for Calvin College engineering students. The Senior Design capstone class focuses on team
and project development as well as various topics on professional development. The first half of the
project, ENGR 339, focuses more on developing the project and completing a feasibility study and the
second half of the project, ENGR 340, focuses more on how to complete the final design and analysis of
the project. At Calvin College, Christian perspectives and faith are the foundation of each class, and the
senior design capstone class is no different. The senior design course aims to not only teach students
about the skills and techniques for completing a senior design project, but also integrates a Christian faith
into each design element and strategy.
1.2 The Team
Team 10 consists of Laura Boluyt, Vincent Rovedatti, Christine De Zeeuw, and Daniel DeVries. The
team consists of two electrical engineers, Boluyt and De Zeeuw, and two mechanical engineers, DeVries
and Rovedatti. The dynamic range of experiences for the team makes them well suited for the project.
Figure 1: The Team
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1.2.1 Laura Boluyt
Laura is an electrical and computer concentration engineering student from Grand Rapids, Michigan. She
has industry experience in control systems and project engineering at Consumers Energy. Laura also has
managerial background through her work experience at Calvin College. Her interest and experience with
control systems and design of automation solutions will be beneficial to this project. In her free time,
Laura enjoys dancing, playing musical instruments, traveling, and serving in the high school youth group
at her church.
1.2.2 Vincent Rovedatti
Vincent is a mechanical concentration engineering student with a math minor, and is from Ripon,
California. Vincent hopes to pursue graduate studies in automotive systems, but would not mind working
for automotive or aeronautical companies. Vincent’s knowledge in automotive work (primarily
restoration of old cars), general knowledge of how cars work and run, and simulating programs will aid in
the aerodynamics and construction of the vehicle. As a research assistant at Calvin College, Vincent
provides experience with CFD (Computation Fluid Dynamics), as well as being very knowledgeable
about the metal and wood shop. In his free time (or lack thereof), Vincent enjoys watching movies,
working out, and making latte art for the customers of the Fish House. After graduation, Vincent will be
working for Temper Inc. in Rockford, MI.
1.2.3 Christine De Zeeuw
Christine is an engineering student with an electrical/computer concentration from Dexter, Michigan. She
is an active member of the Calvin College Wind Ensemble, and is Secretary for the IEEE Student Chapter
at Calvin College. Christine has gained research experience through an internship at the University of
Michigan, and industry experience working as an intern for SeaLandAire Technologies. Her experience
and interest in data collection and analysis will be valuable for the dashboard design and interface. In her
free time, Christine enjoys teaching herself piano, playing tennis, cross stitching, and watching movies.
After graduation, Christine will be working for SeaLandAire Technologies in Jackson, MI.
1.2.4 Daniel DeVries
Daniel is pursuing a Bachelors of Science in Engineering with a Mechanical Concentration at Calvin
College. He is from Grand Rapids, MI. He has gained experience in mechanical engineering through
several summer internships. In his free time Daniel enjoys cycling, rock climbing and disc golf, and is
involved with music at Calvin. After graduation in May 2016 he plans to either pursue a graduate level
degree in medical based mechanical engineering or seek a full time position working in mechanical
design and manufacturing.
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1.3 Project Definition
The objective of Team 10’s project is to design and build a 4-person electric vehicle. The design
of this vehicle will use a previous senior design team’s final product as a starting point,
improving the functionality and design of this final prototype. The Calvin Bolt will be a cross
between a golf cart and a standard car, combining design aspects from both types of vehicles to
provide greater comfort and ease of transportation across campus for guests of Calvin College.
The primary elements of this vehicle include the brakes, steering, electric motor, electronic
dashboard, and overall aesthetic design. The specific goals that pertain to this project are as
follows.
1.3.1 Safety
Passengers will be contained within the vehicle during standard travel and sharp or moderate turns. Road
obstacles such as bumps and holes will not compromise the integrity of the vehicle or the safety of the
passengers.
1.3.2 Ease of Use
Driving forwards and backwards, turning, braking, accelerating, and using vehicle lights should not be
more difficult than operating a golf cart or other vehicle. The dashboard elements will be user-friendly,
and the vehicle controls easy to navigate and operate. The vehicle aims to fill a need for those who have
mobility challenges (i.e. elderly community members or those with a temporary or permanent disability)
and difficulties climbing in and out of a golf cart.
1.3.3 Quality
The vehicle will be fully functional and will be a quality-engineered final product. No element of the
vehicle should be partially functional, and care to produce quality parts shall impact every design
decision.
1.3.4 Maintenance
The vehicle will be easy to maintain and repair so that it will be fit for continued use in the future. Any
necessary documentation for the vehicle will be provided by Team 10.
1.3.5 Aesthetics
The vehicle will be visually appealing and present Team 10’s project in an effective way to Calvin
College’s campus. The vehicle should effectively represent the Calvin Engineering Department through a
vehicle that is aesthetically pleasing.
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1.3.6 Seasonal Outdoor Usage
Taking Michigan’s weather into account, the vehicle will have the capabilities of driving in the winter
months. A front windshield will protect the driver from precipitation and wind that may obstruct the
driver’s view while driving.
1.4 Motivation
Team 10 found this project appealing because there were many aspects of the original design that the
team felt could be improved and modified. This project is a great learning experience because it allows
the team to learn from the strengths and weaknesses of the Volts-Wagon design, incorporating that into
Team 10’s project. This experience will be very relatable to industry and will provide valuable experience
for future jobs and design experiences.
Members of the team have personal experience using a golf cart to provide transportation across campus
for those who have mobility challenges. Members of the team have also become aware of the inability for
the parents of fellow Calvin peers to accompany their child on a campus tour due to their low mobility
and the lack of a vehicle designated for this purpose. Team 10 saw this as an opportunity to improve the
accessibility of Calvin’s campus.
As Christian engineers, this project was appealing because it provided an opportunity to design a system
with the community in mind. Team 10 wished to design the Calvin Bolt to be a vehicle that would both
make the campus more accessible and provide a unique service to the community. God asks his children
to love their neighbors as themselves, and a small piece of this could be providing a vehicle that can allow
all guests of Calvin College to experience the campus. Throughout the design process, the team took the
time to think about what design elements would make the vehicle helpful and meaningful to the Calvin
community, taking the engineering scope of the project and expanding it to fit the needs of the
community.
1.5 Customer
The Calvin Bolt will be designed and built for Calvin College. The original design, completed by last
year’s senior design team, was made for the Calvin Admissions Department, but the Admissions
Department has indicated that they no longer desire an admissions vehicle. Despite this, the team is still
designing the vehicle with the Admissions Department in mind in case they should want the vehicle after
the completion of the project. Should the Admission Department not want the vehicle, it could be used to
promote the Engineering department and provide a service for those who have trouble walking long
distances across campus instead.
Indirect customers for this project are those who have mobility challenges or those who have trouble
walking long distances across campus. The vehicle is being designed to accommodate that group of
people, but not for one particular person.
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1.6 Design Norms
Design norms provide a way for Calvin Engineering students to integrate relationships with God and
those around them into the engineering design process. These guidelines challenge the engineer to
consider outside relationships and consequences.
One design norm that characterizes Team 10’s project is Trust. One of the top priorities for this project is
safety, and the passenger should trust the design and know that it is dependable and reliable. The
passenger puts their safety into the team’s hands, and it is the team’s job to make sure that the customer
can trust the design.
Another design norm that fits into the project is Integrity. Team 10’s design strives to be pleasing and
intuitive to use, demonstrating a complete harmony between form and function. The design also strives to
make Calvin’s campus accessible to all, especially those with mobility challenges or limitations,
promoting human relationships and interaction through this vehicle.
A third design norm that fits into the project is Stewardship. The electric motor provides an excellent way
to minimize the degradation of the environment. Other design elements strive to be an efficient use of
resources such as materials and money.
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2 Requirements
To achieve the project goals listed above in accordance with Calvin College’s policies, there exists a
certain set of requirements.
2.1 Functionality
The vehicle must be fully functional and able to withstand minor and possibly major road disturbances
and weather conditions. The vehicle must be in a stable state at all times, and the brakes must be fully
operational and effective. The frame must be able to withstand the load of up to four passengers and
provide some protection in the event of a crash.
2.2 Capacity
The vehicle must be able to hold 4 passengers safely, and provide the electrical power to transport them
across Calvin’s campus. The vehicle must also be able to fit on Calvin’s sidewalks.
2.3 Speed
The vehicle must operate within the maximum 25MPH speed limit set on Calvin’s campus grounds.
2.4 Safety
The vehicle must include safety features for the driver and passenger such as doors, a parking brake, turn
signals, headlights, and brake lights.
2.5 Time feasibility
The vehicle must be designed, constructed, tested, and fully functional before May 7, 2016.
2.6 Budget
The team has a $500 budget set by the Calvin College Engineering Department. Additional funds can be
acquired upon an approved request, but the team should honor the $500 budget as much as possible.
2.7 Project Deliverables
By the end of the project, the team will have completed a Project Proposal and Feasibility Study (PPFS)
and a Final Report. The team will also provide all drawings, relevant calculations, team notebooks, and a
team website in addition to the final vehicle prototype.
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3 Project Management
3.1 Project Breakdown
3.1.1 Dashboard
The Calvin Bolt will feature an electronic dashboard system to display various instruments and readings,
including, but not limited to: the current speed, remaining battery life, time of day, current date, outside
temperature, and a map of Calvin College. To achieve this, a touch screen display will connect via a
programmable device to serve as a straightforward user-interface for the driver.
3.1.2 Braking System
Similar to most modern day ground transportation vehicles, the Calvin Bolt will implement disc brakes
for stopping. Unlike traditional vehicles, however, the Calvin Bolt will have brakes on just the front
wheels rather than all four. The braking system needs to be able to bring the vehicle to a complete stop in
a distance similar to that of a traditional automobile.
3.1.3 Steering
The Calvin Bolt will implement a rack and pinion steering system. This system is proven to be reliable
with little to no maintenance needed and is very easy to install. The steering system must to be able to
maneuver corners with ease for the driver as well as remain stable when going over a bump in the road.
3.1.4 Electric Motor
The Calvin Bolt will be powered by an electric motor and a 48V battery pack, following the zeroemissions trend for golf carts and other related vehicles. The Calvin Bolt will be using an electric motor
and controller obtained from the 2014/2015 senior design Team 04’s Volts-Wagon, which has the
required capacity to properly propel the vehicle. The motor needs to have enough power to allow the
vehicle to travel at least 5 miles or 30 minutes on a single battery charge.
3.1.5 Frame Design
The Calvin Bolt will be made of aluminum pipe rather than steel in order to decrease the weight and
increase the power to weight ratio. The Calvin Bolt will be created with a design that imitates a modern
hatchback, but still has the soul characteristics of an electric golf cart. The design for the Calvin Bolt
needs to look aesthetically pleasing while keeping its passengers safe and comfortable.
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3.2 Schedule
Each team member maintains a Google Calendar, which is shared amongst the whole team; this allows
the team to remain organized and updated on any potential schedule conflicts.
For the second semester, Team 10 primarily focused on prototype construction and implementation of the
team’s designs. A weekly schedule was outlined on the team’s whiteboard, listing the tasks that were to
be completed by the end of the week. This schedule would be updated each week with new tasks or tasks
that carried over from the previous week.
One section of the whiteboard was reserved for upcoming deadlines and goal completion dates. This
allowed the team to keep track of upcoming assignment or report deadlines as well keeping track of the
target completion dates for elements of the prototype construction.
In addition to the whiteboard, the team also generated a daily work calendar for the final month of the
project, which was the month of April 2016. This daily work calendar was created to ensure that the team
kept moving forward in prototype construction so that the vehicle could be completed and painted before
the Senior Design Banquet on May 7, 2016. One version of this calendar can be found in Appendix A.
3.2.1 Team Meetings
The team chose Tuesday afternoons from 12:30 pm to 4:30 pm as the time when all group members
would be working on the project in the engineering building. This created a time when all team members
would be available for team meetings and progress reports. If no official team meeting was called for that
day, each member was still available and located in the engineering building should the circumstances for
a meeting arise.
3.3 Budget
For the entirety of the project, Daniel DeVries maintains the budget for The Calvin Bolt. This includes
keeping records of all costs associated with the purchase of components and materials, including shipping
costs. While the team collectively acknowledges the necessity of any changes in the design process that
might affect budget, DeVries is responsible to ensure that the budget and bookkeeping are accurately
reflected. An Excel Spreadsheet to organize material costs for the project may be useful.
In efforts to build a cost-effective prototype, The Calvin Bolt will employ as many salvageable parts from
the original vehicle as possible. The team is also fortunate enough to have some parts donated or made
available free of charge.
A contingency in budget will be kept to allow for unforeseen costs to be covered. The detailed breakdown
of the budget is presented in Appendix B.
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3.4 Team Roles
Each member of Team 10 is responsible for one aspect of the design project. While one member is in
charge of a particular design aspect, each member will report their progress to the team for design
verification and assistance. In particular, the members in the same engineering concentration will check
the other’s work to ensure safety and quality of design.
Laura Boluyt is taking the lead on the time, temperature, speedometer, and the design of the main
dashboard tab on the electronic dashboard. She is also the team webmaster, responsible for designing and
maintaining the team’s website.
Daniel DeVries is the head of the braking and steering, and is working on the design process of the frame
and other body elements. He is also the budget manager for the team.
Christine De Zeeuw is the head of the electric motor system, and is taking the lead on the battery life,
Calvin map, turn signal system, and the design of the Calvin Map tab on the electronic dashboard.
Vincent Rovedatti is the head of the design of the frame, powertrain and manufacturing of the Calvin
Bolt, and is working on the design process of the frame and other body elements.
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4 Design Alternatives and Decisions
4.1 Electronic Dashboard
The Electronic Dashboard for the Calvin Bolt will display a variety of metrics and tools that the user
would typically find in newer car dashboard. The dashboard aims to provide the user with features that
will display safety information, such as speed and remaining charge, as well as helpful information such
as a map showing the current location of the user on Calvin’s campus.
4.1.1 Requirements
To guide the design of the electronic dashboard, there exists a set of requirements that must be fulfilled to
create the intended functionality. The first requirement for the electronic dashboard is that it must be
portable, so that it may be installed in the vehicle’s dashboard without the need for a wall outlet to
provide power. Another requirement is that the dashboard must be able to display all the features
adequately. The dashboard must also have the hardware to transmit data efficiently and accurately, using
safe and reliable techniques. Another requirement is that the device chosen must be able to process
incoming data and modify it as necessary. The requirements for the electronic dashboard must be met by
the hardware, operating in the desired fashion.
4.1.2 Data Processor
The microprocessor that would serve as the platform for the electronic dashboard would take care of the
Graphical User Interface (GUI) that the user interacts with. The team first considered a tablet or smart
tablet, which would provide about a 7-10 inch screen. Table 1 lists some of the options for smart tablets
on the market today that the team researched. The prices for the various tablets was higher than the team
desired, and there was no guarantee that each tablet would allow the team to program an app that would
allow outside data coming in from the sensors to be manipulated and displayed as desired. Since the team
required that the dashboard device have the capability to modify data from outside sources (such as
sensors), the team decided not to pursue a smart tablet.
Table 1: A comparison of smart tablet devices considered for the electronic dashboard
TG-TEK Tablet [1]
Apple iPad 2[2]
Samsung Galaxy Tab A [3]
10.1 inches
9.7 inches
7 inches
Screen size
$59.99
$189.99
$149.99
Price
16 GB
16 GB
8 GB
Memory Size
4000mAh
10 hours
11 hours
Battery Size/Life
1 micro USB, 1 3.5mm
3.5mm audio jack
3.5mm audio jack, USB 2.0
Ports
audio jack out
Android 5.1
iOS
Android 5.1
Software OS
Outside of a smart tablet, two alternatives were considered for the dashboard microprocessor: an Arduino
or a Raspberry Pi.
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Both the Raspberry Pi and the Arduino were low in cost, but each had individual strengths that the other
could not provide. Table 2 below lists the various capabilities and strengths of the Arduino and Raspberry
Pi, taking into consideration the article in [4].
Table 2: A comparison of the Arduino and Raspberry Pi
Arduino
Raspberry Pi


Low Cost

Easy sensor collaboration

Easy GUI programming

Large Memory

Multiple USB ports

Open-source
documentation

C programming

Python programming

Code available for
sensors

Display cooperation
Since the dashboard system requires both GUI and sensor integration, the team decided to use both an
Arduino and a Raspberry Pi. Table 2 illustrates that the Arduino is superior for sensors while the
Raspberry Pi is superior for graphics programming; therefore, the Arduino would be used for the sensor
data collection and conditioning while the Raspberry Pi would be used for the GUI platform. An Arduino
was donated to the team, and a Raspberry Pi was made available by Calvin College, which eliminated the
costs for the hardware despite the low cost for each unit.
4.1.3 Touchscreen
The screen for the dashboard had to be small, portable, and easily integrated into the Raspberry Pi with
the screen still big enough for the features to be visible. The team then researched a variety of
touchscreens that were tied directly to the Raspberry Pi. A listing of products on the Adafruit website
showed a range of screen sizes from 2.4” to 7” [5]. The team did find a 10.1 inch option at banggod.com,
but the screen was purely a monitor with no touchscreen capability [6]. While the largest size for
touchscreens was 7 inches, the touchscreen feature allowed the user to select different features to view.
The team chose a 7 inch Touchscreen Monitor for the Raspberry Pi, as shown in Figure 2 below. This
particular screen was chosen due to its larger size for Raspberry Pi related touchscreens, its relatively low
cost for a larger screen, and the available documentation of set-up and operation instructions provided by
both the manufacturer and users. The screen allows for the Raspberry Pi to be directly connected to the
back of the touchscreen onto a minimized electronics board, creating a simple a compact system.
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Figure 2: Raspberry Pi 7” Touchscreen with Raspberry Pi board in front [7]
4.1.4 Features
Team 10 considered several different features to be displayed on the electronic dashboard. During the
brainstorming session during the fall semester, the team determined that the necessary features of the
dashboard included the speed of the vehicle, a map of Calvin’s campus, the remaining battery charge of
the vehicle’s batteries, and the current date and time.
The team had considered adding in a lighting control system to the dashboard to add a fun, colorful to the
vehicle, where the dashboard would control an array of multi-colored LED lights to change the color or
brightness. However, the team determined that this was not an essential feature to the dashboard, so the
team decided to pursue this feature only if the team had extra time after developing the primary features
of the dashboard.
Since the team used current car dashboards as an inspiration for the team’s design, the team decided to
add a current outdoor temperature feature. The final features to be displayed on the electronic dashboard
include the current time, current temperature, current date, speed of the vehicle, remaining charge of the
vehicle batteries, and a map showing the vehicle’s current location on Calvin’s campus.
4.1.5 Sensors
Given the list of dashboard features, the team had to determine which sensors could provide the data for
those metrics and meet the data reliability requirement. Since the map of Calvin’s campus requires the
current location of the vehicle, a GPS sensor was required.
Two alternatives were considered for the GPS sensor as listed in Table 3:
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Table 3: A comparison of an Adafruit and Parallax GPS unit
Adafruit Ultimate GPS
Parallax GPS
Cost
$39.95
$37.49
Positional Accuracy
1.8 meters
< 2.0 meters
Update Rate
Arduino compatibility?
1 second
Yes
1 second
Yes
Source code available?
Yes
Yes
Power Regulation?
No
Yes
While both GPS units were nearly identical in offered features, the team chose the Parallax GPS sensor
because it provided power regulation for the sensor and was the brand choice for the 2014/2015 VoltsWagon. The power regulation was an important feature since regulation ensures that any variations (peaks
or minimums) in the power supply to the GPS do not damage the circuitry. Parallax GPS units have also
been used by Senior Design teams in the past, and the teams who used them were happy with the
performance of the GPS. Both the power regulation and the successful use results convinced the team the
Parallax GPS was the best choice.
The GPS sensor would be able to provide the data for the mapping, speed, date, time and battery life
features of the dashboard. Therefore, the temperature feature required another sensor. The team chose to
purchase a Texas Instruments LM35 Temperature Sensor because of its low price, available
documentation for integration with an Arduino, and evidence of its widespread use.
4.1.6 Data Communication
Since the Arduino was utilized to collect sensor data, it would have to transfer that data over to the
Raspberry Pi so the Pi could plug the data into the GUI application. The team found three different
alternatives for communicating between the Arduino and Raspberry Pi, as described by Oscar Liang in
three articles that described these different methods of data transfer [8, 9, 10].
The first alternative was to connect the Arduino and Raspberry Pi using a USB connection [8]. This was
the simplest connection because it required only a USB A to B cable. This connection was also a safe
connection because the USB cable is a high quality cable and current overloading of the port is not a huge
issue. The second alternative was to send data by connecting the GPIO pins on the Raspberry Pi to the
Serial pins on the Arduino [9]. This alternative requires a voltage divider or logic level converter for the
circuit since the Arduino Serial pins have a different voltage than the Raspberry Pi GPIO pins. The third
alternative was to send data by connecting the I2C (Inter-Integrated Circuit) pins, setting the Raspberry Pi
as the master device and the Arduino as the slave to the Pi [10].
The team chose to send data using the first alternative, which was the USB connection. The team chose
this alternative because it was the simplest to integrate through coding, a safe method of data transfer, and
required the least amount of materials. Another reason for choosing the USB connection was that it
allowed for the Arduino to be located farther away from the Raspberry Pi than with the other alternatives.
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The GPS sensor requires an open view of the sky and this means that it would possibly have to be
installed in a location that was farther away from the Raspberry Pi, and the USB cable allows for this
extra distance.
4.1.7 Power
The Raspberry Pi required an operating voltage and current of 5V and 2A respectively, which also was
enough to power the Arduino through the USB port. The touchscreen also required 5V and 2A to power
and function properly.
Since the DC to DC power converted used in the overall electrical system of the vehicle provides 12V,
the team decided that it would be better for the dashboard to have its own independent power supply
instead of dealing with stepping down the voltage to the Raspberry Pi and touchscreen. The
documentation for the touchscreen and the Raspberry Pi also suggest that the power supply should
provide a steady 5V and minimum 2A, where the power input is in the form of a micro USB.
Research into portable Raspberry Pi power supplies, such as the article found in [11] by Christian
Cawely, found that common solutions involved portable battery designed to charge cell phones. Portable
battery banks provide a range of output voltages, output currents, and capacity, and certain battery banks
can provide the desired combination for the Raspberry Pi. The team chose an Innogie 10400mAh Portable
Charger with 5V/2.4A USB output because the output met the voltage/current requirements and it had a
low price point of about $15 per unit.
The team purchased two battery packs because the documentation for the touchscreen recommended that
the touchscreen be powered by a separate power supply from the Raspberry Pi. While there were other
alternatives for powering the screen through the Raspberry Pi, the team decided to follow the suggestion
of the manufacturer to ensure that the proper amount of voltage and current was being supplied at all
times. Additional ports connected to the Raspberry Pi such as the USB cable to the Arduino pull
additional current, and the team decided not to risk overloading current from the Raspberry Pi.
4.1.8 Operating Specifications
Electronics are often not as robust as mechanical systems, and since the electronic dashboard would be
operated outdoors the operating specifications had to be observed. The Raspberry Pi has several
microchips made with Silicon that provide the main processing power. The microchips have a
temperature rating of -25° to 80° C, and the capacitors on the board have a temperature rating of -25° to
85° C [12]. These temperature ratings are the temperatures when the silicon will die, and do not take into
consideration the heat generated when the system is in use. To ensure that the team remains safely in the
temperature range, ventilation holes on the case or enclosure must be added to allow heat to escape during
operation.
According to the touchscreen’s manual, the screen was “designed for reliable operation at normal ambient
room temperatures”. However, the team has taken the screen outside for testing purposes when
temperature were around 40° F and 85° F and the screen was fully functional. The team decided that the
14
touchscreen could handle a wider range of temperatures, but caution should be observed when operating
in extreme temperatures.
The Arduino’s microchip can handle a temperature range of -40° to 85° C, while the other components on
the board can handle -20° to 80° C [13].
The Raspberry Pi, touchscreen, and Arduino are not waterproof, requiring their enclosures to have both a
way to keep the components away from water and provide adequate ventilation.
4.1.9 Case
To provide protection for the touchscreen and Raspberry Pi, a case had to be designed to cover the
exposed electronics. The current designs for the Raspberry Pi Touchscreen case were either expensive for
the solution provided or were simply a stand instead of a surrounding case.
Since no immediate solutions were readily available and the team had a time constraint, the team decided
to design their own case for 3D printing. Research into a variety of different case types provided
inspiration for the team’s design. Figure 3 shows the front piece from a multi-piece design found in [14],
which has an indented slot on the back that the screen would slide into. This allows the screen to be
surrounded and supported by the case.
Figure 3: Front Piece of a Touchscreen Case Design [14]
Figure 4 shows another piece from the same design, showing a clear acrylic piece that surrounds the
mounting holes on the back of the screen. The team chose to incorporate this idea because it would hold
down more of the screen while still leaving the mounting holes available.
15
Figure 4: Third Piece of a Touchscreen Case Design [14]
Figure 5 shows another case design, which can be found in [15]. Much like the case design from [14], the
case is comprised of several layers of clear and black acrylic. The team chose to model the case with the
overall shape and size as seen in Figure 5 since it was the most appealing and had aesthetically pleasing
locations for the screws.
Figure 5: ModMyPi Touchscreen Case and Display Stand Design [15]
Figure 6 shows the design for a case the team had originally wanted to use. The source provided all of the
3D printed files, but the team found that the files could not be modified to fit the needs for the team’s
16
application. Instead, the team chose to design a case that fits over the Raspberry Pi, using the designs in
Figure 6 as a guideline for how the final product should look.
Figure 6: 3D Printed Touchscreen Case Design [16]
Figure 7 shows the final design for the case as seen from the front and back. The case consists of 4 layers
that screw together to form one unified case. The first three layers surround the touchscreen and the fourth
layer covers the extended Raspberry Pi that protrudes from the back of the screen.
Figure 7: Final Case Design as seen from the Back (L) and Front (R)
17
4.1.10 Final Design
The final schematic and connections for the electronic dashboard can be found in Figure 8 shown below.
Figure 8 represents the final schematic that would be implemented in the prototype. The power supply is
connected through a USB to micro-USB cable, the Arduino is connected through a USB Male A to B
cable, the touchscreen and Raspberry Pi are connected through a 15-way FPC connector, and the other
connections will be connected through jumper wires.
Figure 8: Final Circuit Design for the Electronic Dashboard
4.2 Dashboard GUI
The dashboard interface that will appear on the touchscreen for the user to interact with is called a
Graphical User Interface (GUI). This GUI is created through code that handles all of the data coming in
from the Arduino and sensors and displays them in an accessible interface for the user.
4.2.1 Requirements
Requirements for the dashboard GUI helped the team decide how the features were to be implemented
and what techniques would be used to achieve the desired results. One requirement is that the GUI must
implement all of the features so that they are clearly visible to the user. Another requirement is that the
GUI must update every second to match the data output rate of the GPS sensor. To ensure that the user
only has to power the dashboard on to have the GUI appear requires that the system be fully automated,
running the code automatically when power is supplied. Another requirement is that the GUI must be
user-friendly, displaying the information in a clear way and allowing the user to navigate with ease.
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4.2.2 Coding Language
The coding language that was chosen for the GUI on the Raspberry Pi was the Python programming
language. The team chose this language because of the availability of libraries that would provide the
functions that would allow the team to make the interface look as desired. The team had considered the C
programming language, but the lack of GUI programming functionality pushed the team towards Python
instead.
The team chose to use the Python PySide library for writing the GUI application itself. Members of the
team have previously used the PySide libraries to create a GUI application at previous internships. The
team chose this library because it provides far more functionality and high-level programming than
default libraries; there is also a large amount of documentation to go with the library including sample
code other users have written for a variety of applications.
The coding language for the Arduino is the C programming language, which is the default programming
language for Arduino files. The team decided not to pursue changing the programming language to
Python to maintain a common programming language since the documentation for writing Arduino code
for the GPS/temperature sensor was in C. The bulk of the coding to be done was on the Raspberry Pi, so
the team determined that the minimal Arduino coding could be accomplished in C.
4.2.3 System Automation
To ensure that the user does not have to do anything to run the code for the dashboard, a number of
changes to the Raspberry Pi system files had to be made so the dashboard GUI would start up
automatically when powered on.
For the GUI code to start up automatically when the Raspberry Pi was turned on, a specific list of steps
had to be achieved: the Raspberry Pi had to be logged into, the Raspberry Pi server had to be started, and
the code had to be run.
Figure 9 illustrates the commands that had to be entered into the files listed to automatically start the
Raspberry Pi, taken from the article in [17].
19
Figure 9: Instructions for Automatically Logging in to the Raspberry Pi [17]
Figure 10 illustrates the commands that had to be entered to automatically start the Raspberry Pi GUI on
the X server.
Figure 10: Instructions for Automatically Starting the Raspberry Pi X Server [17]
The final step in the automation process was to start the dashboard GUI code once the server and
Raspberry Pi. Figure 11 shows the steps taken to automatically run the dashboard GUI code.
Figure 11: Instructions for Automatically Running a Python Script [18]
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4.2.4 Layout
The features displayed on the dashboard as listed in Section 4.1.4 above are the speed, date, time,
temperature, remaining battery charge, and a map of Calvin College. A multi-tab layout was chosen for
the GUI since all of the listed features cannot fit onto one screen. The Calvin Campus map was placed
onto a second tab since it would require as much screen space as possible to see clearly.
The multi-tab layout also allowed the team to split up the design of the two tabs among the team’s two
electrical engineers, Boluyt and De Zeeuw. Each tab could be designed and tested individually before
combining them into a multi-tab widget.
4.2.5 Continually Updating GUI
Since the sensors are continually sending new data to the Raspberry Pi once every second, the dashboard
GUI would also have to be updated once a second to keep up with the incoming data. The data is sent out
from the Arduino through serial communication at a 9600 baud rate; the Raspberry Pi watches the serial
port for new data coming in, which essentially acts as an infinite loop, stopping only when the system is
stopped or shut down. The GUI application also runs like an infinite loop, quitting only when the user
kills the application. Through preliminary coding, the team found that only one infinite loop could be run
at a time.
The team considered two possible solutions to this problem: interrupt signals or multithreading. Interrupt
signals are signals sent by external devices that tell the current process to stop and execute a set of
instructions as specified by the interrupt signal [19]. In the case of the dashboard GUI, an interrupt signal
could be triggered when new data comes in over the serial port, prompting the GUI to update the
dashboard screens. Multithreading is when a program can run multiple threads at the same time, where
threads allow the program to run several actions at once [20]. Multithreading allows the program to
perform multiple operations at once, which in the case of the dashboard GUI would be to watch the serial
port for new data and run the GUI application.
The team learned from previous coursework that dealing with interrupt signals that they can be very
challenging to work with and require exact and specific instructions for the signals to operate properly; as
a result, the team chose to pursue multithreading. As the team began looking into multithreading, the team
found documentation for setting up a continually updating GUI using multithreading on the GitHub found
in [21]. According to [21], one thread would be used for watching the serial port for new data, storing the
results into a queue, and one thread would be used to run the GUI application itself.
4.2.6 Final Design
Figure 12 shows a block diagram for the basics of the dashboard GUI with the functions as seen in the
final code found on the team’s website [25]. This process flow runs continuously until the application
process is terminated.
21
Figure 12: Dashboard GUI Process Flow Chart
Figure 13 shows the final design for the main dashboard tab. The team sought to create a design that was
as familiar as possible to dashboards users would have seen elsewhere, such as in a car.
Figure 13: Final Design for the Main Dashboard Tab
Figure 14 shows the final design for the GPS mapping tab. Included on this tab are the map of Calvin
College, a campus doors checkbox, a map view selection box, the name of the serial port, a compass, and
the quit button.
22
Figure 14: Final Design for the Calvin Map Tab
4.3 Brakes
The team decided to use hydraulic disc brakes in order to give the Calvin Bolt the maximum braking
power and efficiency possible. A hydraulic brake kit containing the items shown in Figure 15 was
purchased and implemented into the design as shown in Figure 16.
Figure 15: Jake’s Hydraulic Disc Brake Kit [22]
23
Figure 16: Front Wheel Support and Brake Design
The main cylindrical brackets on which the wheel bolt were taken from the 2014-15 Volts-Wagon and
modified to accommodate the rotor spacers from the brake kit. A golf cart brake pedal assembly was
purchase which could be mounted directly to the components included in the brake kit.
4.4 Steering
The team decided to use a rack pinion system (Figure 17) found in the engineering storage room in order
to give the Calvin Bolt the best possible stability while steering and is a widely used steering system for
most production cars today.
Figure 17: Rack and Pinion System
24
4.5 Electric Motor and Controller
The electric motor and controller are two of the most powerful and important electrical components of the
vehicle. They provide the electrical power necessary to move the vehicle, drawing power from the four
high capacity batteries.
4.5.1 Requirements
The requirements set for the electric motor and controller were to ensure that the vehicle could operate
safely to perform the tasks required. One requirement is that the motor must be capable of moving
1400lbs of load weight in addition to the 200lbs of the frame under any road conditions found on Calvin’s
campus, such as hills and bumps. Another requirement is that the motor controller should safely handle
the battery charge and control the motor according to the throttle input of the user. It is also required that
the vehicle must be able to drive across Calvin’s campus on a single battery charge.
4.5.2 Electric Motor
The Calvin Bolt uses a Mars ME0708 8HP electric motor, as seen in Figure 18, which was taken from the
2014/2015 Volts-Wagon. Calculations for the motor, found in Appendix C, demonstrate that the motor is
capable of providing the power to transport the vehicle. Despite the larger size of the vehicle as compared
to the previous year, the calculations in Appendix C show that the motor was still within the rated
horsepower limits. The motor can be considered water resistant, meaning that some water splatter
generated from the axle spinning on a puddle will not completely damage the motor. However, the motor
is not waterproof and the user should take precautions to ensure no motor gets into the motor. Detailed
specifications of the motor can be found in Appendix D.
Figure 18: Mars ME0708 Electric Motor
25
4.5.3 Motor Controller
The team used an Alltrax SPM 48400 motor controller, as seen in Figure 19, which was also taken from
the 2014/2015 Volts-Wagon. The controller reads a 0-5K throttle potentiometer and turns on the motor
when the driver pushes the gas pedal. The controller can handle up to 400 Amps, which is within the
motor’s current output of 100A continuous and 300A maximum.
The Alltrax controller includes a programmable feature, which allows the user to program a variety of
settings on the controller using a PC. Some of the most important settings on the controller are the
maximum current drawn from the batteries, maximum current drawn from the motor, maximum voltage
input from the batteries, and minimum voltage input from the batteries. These values allow the controller
to shut down or reset if the current or voltage through the system reaches dangerous levels, telling the
controller under what conditions it is allowed to operate or run the motor. The controller has an operating
temperature range of -25° C to 85° C with a controller shutdown temperature of 95° C. The controller
itself is waterproof, but the wire connections coming into the controller are only waterproof if the user has
taken the steps necessary to make the terminals waterproof. Images of the programming settings can be
found in Appendix E.
Figure 19: Alltrax SPM 48400 Motor Controller
4.5.4 Throttle Potentiometer
The throttle for the Calvin Bolt is a Curtis PB-6 0-5K potentiometer box (pot box), which was taken from
the 2014/2015 Volts-Wagon. The accelerator pedal is attached to a lever on the pot box, which changes
the resistance of the potentiometer as the lever is rotated. As the resistance changes, differing amounts of
current flow to the motor controller, and the level of current tells the controller how fast the motor should
be running.
26
When the team inspected the pot box and the connections from the previous team, it was discovered that
the leads of the potentiometer were bent to the point where there was almost contact between the leads.
As the team bent the leads away from each other, one of the leads snapped off to the point of no repair, as
seen in Figure 20.
Figure 20: View of the Broken Lead on the Potentiometer of the Throttle Box
While replacing the entire component would cost roughly $110, the team discovered that the
potentiometer itself could be replaced for roughly $10 since the pot box could be disassembled. The team
replaced the broken potentiometer and reassembled the fully functioning pot box.
4.5.5 Batteries
To meet the requirement that the vehicle should be able to drive across Calvin’s campus in a single
battery charge, the batteries used by the Calvin Bolt needed to have the proper capacity to meet this
requirement. The team originally intended to use the batteries from the Volts-Wagon, which were 12V
VMAX Tanks Solar Charge Tank batteries with a 60Ah capacity. After more careful consideration of the
required capacity of the batteries, the team decided, with the advice of a VMAX Tanks consultant
Abraham Ghaleb, to pursue a larger capacity.
The team purchased two 12V VMAX Tanks Solar Charge Tank Extreme batteries with a capacity of
155Ah while VMAX Tanks generously donated the other two. The team anticipates a trip length around
45~60 minutes, depending on the driving conditions.
4.5.6 Final System Configuration
The final system configuration for the electric motor, batteries, motor controller, and throttle
potentiometer can be seen in Figure 21. Figure 21 shows the connections between these components, and
the full schematic can be found in Section 4.10.7. The connections shown in blue used 1/0 AWG power
cable while the red connections used 4 AWG based on the power line ratings specified by the Alltrax
documentation found in Appendix F.
27
Figure 21: Electric Motor System Schematic
4.6 Frame Design
The frame design, as you can see in Appendix G - Original Frame, went through multiple iterations. At
first, the team wanted to make the vehicle small with constant radius pipes. The team decided against the
first design due to harshness of manufacturing the constant radius pipes and not being able to find a
supplier able to produce these parts nearby.
The team then decided to change the first design to only straight pipes, shown in Appendix G - Revision
A. This resulted in a large decrease in cabin room compared to that of the original design.
Therefore, the team decided to redesign the vehicle so that the Calvin Bolt was bigger - feeling more like
a car - and more spacious than the 2014/2015 Volts-Wagon. The redesign can be seen in Appendix G Revision B, in which only straight pipes are utilized, but the vehicle still remains aesthetically appealing.
After initially running tests in FEA on strength and loading capacity of the frame, the team noticed that
the new design was using excess material to get the desired strength and capacity.
Due to the FEA findings, the team decided to design the base of the frame using square tubing instead of
straight piping, as shown in Appendix G - Revision C. The square tubing base gave the Calvin Bolt a
more rigid platform and helped with the strength and capacity that was desired. This particular design was
changed 5 times to accommodate for the front and rear suspension, depicted in Appendix G - Revisions
D-H.
The final design that met all the team’s goals for both cabin room, load capacity, and aesthetics can be
seen in Appendix G - Revision H.
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4.7 Suspension Systems
4.7.1 Front Suspension and Wheel Brackets
In order to minimize the cost of the Calvin Bolt, the front suspension system was initially designed to
reuse the coilovers and front wheel brackets from the 2014-15 Volts-Wagon project. A new set of control
arms were designed to fit within the new frame and mate with the old wheel brackets. The design is
shown in Figure 22.
Figure 22: Original Front Suspension Design
The model shown in Figure 22 was created in Solidworks and was created in such a way that allowed the
wheels to be turned to simulate the turning radius of the wheels. This simulation revealed that the front
wheel well of the vehicle was not long enough to accommodate the steering system. One reason for this
interference was the distance between the center of the wheels and the center of rotation of the wheel
bracket around the front suspension control arms. A new wheel bracket was designed to decrease this
distance and improve the turning radius of the vehicle. The bracket, as shown in Figure 23, was designed
to wrap around the brake calipers in order to get the wheel closer to its center of rotation around the
control arms. The front wheel axles were also moved slightly towards the rear of the vehicle in order to
give the system a castering effect.
29
Figure 23: Front Wheel Bracket Design
4.7.2 Rear suspension
The team decided to reuse the rear axle and leaf springs from the 2014-15 Volts-Wagon project in order
to reduce the total cost. New brackets were designed to mount the front end of the leaf springs to the
vehicle and a new set of shackles and shackle mounts were designed to allow the leafs to properly extend
within the frame. The design is shown in Figure 24. The elements were designed using aluminum so that
they could be welded directly to the aluminum frame.
Figure 24: Rear Suspension Design
4.8 Seats
The 2014/2015 Volts-wagon design included seats that were extremely low to the floor of the cabin,
causing passengers to feel very uncomfortable while sitting in their vehicle. Team 10 wanted to address
this issue by designing front and rear seats to help make the passengers feel comfortable.
30
The team accomplished this by designing adjustable front seats, allowing the driver to adjust his or her
seat to properly reach the gas and brake pedal. The team decide to utilize an electric power seat rather
than a mechanical adjustable seat because the latter is very rigorous to manufacture and design. The front
power seat design can be seen in Figure 25. The back seat design can be seen in Figure 26.
Figure 25: Front Power Seat Design
Figure 26: Seat Frame
4.9 Doors
Team 10 wanted to make the Calvin Bolt the width of a golf cart but the feel of a car. To make the Calvin
Bolt feel like a car, the team decided on making doors instead of a more traditional safety slide off bar
that one typically finds on golf carts.
To make the Calvin Bolt feel more spacious, the team decided to implement suicide doors. Suicide doors
are when front and back doors open in different directions, allowing more space for the user to get in and
31
out very easily. The advantage of a suicide door design requires no B pillar to support the rear door,
whereas a traditional door requires a B pillar.
To open and close the door, the team designed a dead bolt latching mechanism as seen in Figure 27.
Figure 27: Dead Bolt Latching Mechanism
4.10 Auxiliary Electrical System
The auxiliary electrical system of the Calvin Bolt includes all of the electrical elements that are not
critical for the functionality of the system: headlights, rear lights, a brake light, turn signal lights, a seat
gearmotor, and an LED strip for underbody lighting. These components include necessary safety features
as well as features that provide greater functionality to the vehicle such as power seats.
4.10.1 Requirements
The requirements for the auxiliary electrical system are to ensure that the system can operate safely and
reliably. The system must operate at a maximum of 12VDC and 20ADC. Another requirement is that the
system must be able to integrate smoothly into the vehicle.
4.10.2 DC to DC Converter
To meet the 12VDC and 20A requirement, a DC to DC converter was used to take the 48V of the battery
pack and safely convert it into 12V. The converter is rated at 20A of output, and has a 10A fuse at the
input to protect the converter from any current surges.
In addition to providing a safe 12V, the DC to DC converter also ensures that the batteries are equally
drained. Connecting directly to one of the vehicle’s 12V batteries would drain that particular battery much
faster than the other three, which will push the batteries to an under-voltage situation much faster. The
DC to DC converter pulls voltage/current from all four batteries at once, therefore draining the entire pack
equally.
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4.10.3 Front and rear lights
Both the front and rear lights were reused from the 2014/2015 Volts-Wagon. The lights were rated at the
proper voltage and current, so the team decided to reuse these parts.
The headlights are Roadshock Clear Lens Halogen Lights and the rear lights are Optronics Rectangular
Clearance Lights.
4.10.4 Turn signal system
The team conducted research into turn signal kits that could be purchased for universal vehicle
applications. The team found that complete turn signal kits could be purchased for around $100 such as
the kit found in [23]. The team decided to pursue a ‘homemade’ solution to save on money and to make
the system simpler.
Turn signal systems can be made using just a switch, flasher unit, and lights/bulbs [24]. The team found
four cheap 2” LED amber lights, which meant an LED flasher unit was required: the team purchased a
United Pacific 12V electronic LED 2-prong flasher. Figure 28 shows a schematic for a turn signal system
that the team used to guide the design.
Figure 28: Turn Signal Schematic [24]
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4.10.5 Brake light
The team wanted to add a brake light feature so the other drivers on the road and any other observers
would be aware of when the vehicle was braking. Purchasing an LED strip to serve as the brake light was
considered, but the team wanted to reuse as many parts as possible to promote stewardship in the vehicle.
A cuttable 5m red LED strip was used by the 2014/2015 Volts-Wagon project as underbody lighting, of
which Team 10 decided to cut a portion to use for the brake light, saving money and reusing available
materials.
4.10.6 Power Seat Motor
One of the primary goals of the Calvin Bolt was to provide more accessibility to a variety of body types
and physical needs. One way to provide such accessibility was through the addition of adjustable front
seats to the vehicle design. Movable front seats provided the ability for drivers of different heights to feel
comfortable reaching the pedals and driving the vehicle safely.
The team chose to use a gearmotor to provide power seats instead of a slide-and-lock system, as explained
in section 4.8. To meet the 12V and 20A requirement, the team purchased a Bosch 62 RPM 12V 2A
Gearmotor that is reversible and intermittent duty.
4.10.7 Final Design
Figure 29 shows the complete electrical system of the Calvin Bolt, combining the primary and auxiliary
electrical systems. The arrows indicate the direction of current flow through the system.
Figure 29: The Full Schematic for the Calvin Bolt
34
5 Prototype Construction
5.1 Electrical System
5.1.1 Cabling
The team purchased new power cabling for all of the power cable connections that had to be made to
ensure the team had enough length to the cable, and that the cable was properly rated for the team’s
application. The team cut all of the power cables that were shown in red and blue in Figure 21 of Section
4.5.6 based on the various lengths between connections .The ring terminal connectors were crimped to the
cable using a vice grip in the machine shop and then wrapped with electrical tape to ensure the
connections were insulated and well covered. The cut cables can be found in Figure 30.
Figure 30: The Cut Power Cables for the Electrical System
5.1.2 Dashboard Integration
Figure 31 shows the dashboard console that was built for the integration of the vehicle’s switches into the
dashboard area: Forward/Reverse, Power, Lights, and underbody lighting. The electronic dashboard was
mounted to the upper face of the console with the power switches for the Raspberry Pi and Touchscreen.
35
Figure 31: Dashboard Console
5.1.3 Vehicle Integration
The four batteries were mounted in the trunk space at the back of the vehicle, as seen in Figure 32. The
motor controller was mounted below the batteries, as seen in Figure 33. According to the wiring diagram
for the Calvin Bolt’s electrical system, shown in Figure 29, six cables connect from the forward/reverse
switch to the motor controller, which would essentially mean running these cables the length of the
vehicle. To reduce the amount of cable required to achieve this, two short jumper cables were cut to
connect the two positive leads together and the two negative leads together, eliminating the need for two
of the long cables.
Figure 32: The Four Batteries Aligned as they would be in the Trunk
36
Figure 33: Motor Controller Mounting Location
5.2 Electronic Dashboard
5.2.1 Case Assembly
The case for the dashboard touchscreen and Raspberry Pi was printed using Calvin ASME’s 3D printer,
and the results can be seen in Figure 34. The pieces stack on top of each other in the numerical order
shown in the figure.
Figure 34: The Layers of the 3D Printed Touchscreen Case
37
The case was held together using ¼ inch screws, washers, and nuts for the four mounting holes on the
outside of the case. The fourth component of Figure 34 above was mounted using four M3.0 screws.
Figures 35 and 36 show the case as seen from the front and the back.
Figure 35: The Front View of the Assembled Touchscreen Case
Figure 36: The Back View of the Assembled Touchscreen Case
38
5.2.2 Sensor Package
The Parallax GPS and the LM35 temperature sensor were mounted on top of the Arduino through the use
of a plain protoboard as seen in Figure 37. Stackable Arduino pin shields extended the pin connections of
the Arduino to be above the protoboard layer while holding the protoboard flat on top of the Arduino. The
GPS was connected into a pin shield that was mounted perpendicular to the extended Arduino pins as
seen in Figure 37. This allowed the GPS to be easily removed without damaging the leads in the event of
a part replacement or a reconfiguration of the system in the future.
Figure 37: The Sensor Package
5.2.3 Vehicle integration
The electronic dashboard was mounted to right of the steering wheel, as shown in Figure 38, so that the
touchscreen could be easily accessed in an intuitive manner. A dashboard console was designed to
conceal the back of the electronic dashboard, including the Raspberry Pi, wiring, battery packs, Arduino,
and sensors. This console also allowed for natural accessibility to the various switches and can be seen in
Figure 38. Figure 39 shows a view from the rear of the console where the team added a door that could
allow the team to access components inside the console from the hood area.
39
Figure 38: Dashboard Console
Figure 39: Rear View of Dashboard Console
40
5.3 Prototype Construction
The Figure 40, the team constructed
the base square tubing frame and the
base front suspension.
Figure 40: Base Frame
In Figure 41, the team constructed the
front suspension supports and
finished the front bumper.
Figure 41: Front Suspension Support
41
In Figure 42, the team constructed
the rear suspension support and
started to drill holes for the
circular tubing that hold the
panels.
Figure 42: Rear Suspension Support
In Figure 43, the team had a
setback. The team had to cut off
the front suspension support to
add 2 extra inches of wheel well
to have enough room to steer.
The team also added the rear
bumper.
Figure 43: Setback Day
42
In Figure 44, the front
suspension support is
reattached.
Figure 44: Front Suspension Support Reattached
In Figure 45, the vertical circular
tubing is constructed.
Figure 45: Vertical Circular Tubing Beams
43
In Figure 46, the rear suspension and axle are assembled.
Figure 46: Rear Suspension and Axle
In Figure 47, the front A-arms are constructed and
attached to the frame.
Figure 47: Front A-arm Suspension
44
In Figure 48, the front A-arm suspension with the
coilover shocks from last year’s project, tires,
wheel bracket and hydraulic disk brakes.
Figure 48: Complete Front Suspension
In Figure 49, the coilover shocks from last year
were replaced because the coilover shocks were too
small and insufficient for a large vehicle like the
Calvin Bolt, so the team decided to buy a bigger
coilover shock to maintain the ride height and
stability of the vehicle.
Figure 49: Front Coilover Suspension
45
In Figure 50, the team constructed
the front exterior design of the
Calvin Bolt.
Figure 50: Front Exterior Design
In Figure 51, the team constructed
the rear exterior design of the
Calvin Bolt.
Figure 51: Rear Exterior Design
46
In Figure 52, the team
constructed a wooden
apparatus to hold up the
roof while we welded the
A and D pillars on.
Figure 52: Roof Construction
In Figure 53, the team
loaded up the frame to
send to digital
fabrication to get the
panels welded on
Figure 53: Frame Transported to Digital Fabrication
47
In Figure 54, the team constructed
the seat frames for both the front
and back seats.
Figure 54: Frames for Seats
In Figure 55, the team
transported the frame with the
panels welded on from digital
fabrication back to Calvin
College.
Figure 55: Calvin Bolt with Panels
48
In Figure 56, the team
constructed wood
flooring and roof top,
and constructed door
frames.
Figure 56: Calvin Bolt with Seats and Doors
In Figure 57, three square aluminum support beams
were welded to the vehicle to reduce the deflection of
the frame. The team found that the doors could not
close when just one person was on the frame, so the
team added the support beams to decrease the
deflection allowing the doors to close when people
were inside the vehicle.
Figure 57: Addition of Support Beams
49
In Figure 58, the team
completed the rack and pinion
steering system and installed the
brake pedal, connecting the
hydraulic disc brake fluid lines
as well.
Figure 58: Completed Steering and Disc Brakes
Figure 59 shows the vehicle as
it appeared before being sent
off to paint. As seen in the
image, the vehicle also has a
liftable hood panel to allow
both access to the front of the
vehicle and visibility of the
front components for
educational opportunities.
Figure 59: The Calvin Bolt before Paint
50
Figure 60 shows the vehicle in
the paint studio of the Calvin
College Physical Plant. The
color chosen was Calvin
maroon, and two coats were
applied by the Calvin College
Physical Plant.
Figure 60: The Calvin Bolt in the Paint Studio
In Figure 61, the battery box
covers for the vehicle’s four 12V
batteries were mounted, ensuring
that the passengers cannot touch
the live terminals of the battery
while the vehicle is in operation.
Figure 61: Battery Box Covers
51
In Figure 62, the lights and wiring were installed
and the detailing for the vehicle was in progress.
The team obtained decals from Signmakers, Ltd
and also spray painted a bolt shape onto the doors.
Figure 62: Installation and Detailing
In Figure 63, the team installed the seats, carpet, steering
wheel and electronic dashboard. The team also would
install a black canvas roof supported by a wood piece.
Figure 63: Component Installation
52
5.4 Final Product
The final prototype as seen on May 7, 2016 can be found in Figure 64. Figure 65 shows the view of the
vehicle from the rear.
Figure 64: Final Prototype (Front View)
Figure 65: Final Prototype (Rear View)
53
5.5 Future Work
During the construction of the prototype, the team found that certain design features could not be
implemented in the desired manner due to a lack of time. Certain features were dropped or modified from
their original design to allow the prototype to be finished with the basic functionality. The elements that
were eliminated or modified from the project were elements that were not critical to the structural
integrity or operational integrity of the vehicle.
5.5.1 Mechanical Future Work
The Calvin Bolt needs to have its hydraulic disc brakes bled with a vacuum press and obtain a collar for
the steering wheel. While bleeding the hydraulic disc brakes by hand, the team noticed that the master
cylinder is very small and did not have enough internal pressure to get all of the air out of the brake lines,
giving the Calvin Bolt unreliable braking. The team suggests that the hydraulic disc brakes get
professionally bled by a vacuum press or an adaptive pump. The steering wheel for the Calvin Bolt also
needs to have a collar so the steering wheel does not come out while driving. Both the brakes and steering
are simple fixes and will allow the drive not to worry about losing control of the vehicle while driving.
The team also simplified the door locking mechanism by making the lock just a lever that is mounted on
one door and falls to hold the other door in place. This mechanism allow the locking system to be simpler
to implement, saving time to manufacture and install a deadbolt locking mechanism.
The team also removed the adjustable front seat feature due to both a lack of time and a lack of parts. The
team required a threaded rod that was one inch in diameter, 13 inches long, and had 4-6 threads per inch.
The team was unable to find an appropriate rod in the Calvin Metal Shop, and the team could not find a
threaded rod that would be able to arrive in time for installation. Due to the other delays experienced by
the team, the team decided to drop the power front seat option. The team then considered implementing a
mechanical adjustable front seat mechanism, but the team decided to drop the adjustable front seat feature
altogether to allow for more construction time of the critical elements such as brakes and steering.
5.5.2 Electrical Future Work
For the electronic dashboard, the team encountered an issue with the automatic start-up of the dashboard
program. The team got an error message stating, “QGtkStyle was unable to detect the current GTK+
theme”, which caused the GUI application to only display some of the features that were to be presented
on the screen. After consulting with professors in Calvin’s computer science department, the team still
had not found a solution to the error. The team decided to write an instructional file on the desktop that
would guide the user through the steps required for set-up once the Raspberry Pi and touchscreen booted.
While not ideal, the team could not run the code automatically, so an instruction file was determined to be
the best option.
The battery life feature of the Calvin Bolt was unable to be tested and implemented due to a lack of time.
The team wrote code that would determine the remaining battery life of the vehicle based on whether or
54
not the vehicle was accelerating or climbing a hill (change in elevation). The team had planned on
modifying the code calculations based on real time data taken during testing, but the team did not have
the testing time to modify or implement this feature.
The team was also unable to complete the lighting system in the Calvin Bolt. The team simply did not
have time to properly integrate all of the wires and test the system due to the mechanical delays
experienced earlier in the project. Given more time, the team is confident that the lighting system could
be finished and operational.
55
6 Testing
6.1 Electronic Dashboard and GUI
The communication between the sensors and the dashboard GUI was tested several times before
integration with the vehicle. The Parallax GPS sensor, LM35 temperature sensor, and serial
communication from the Arduino to the Raspberry Pi were all tested individually to ensure that each
piece worked on its own before integrating them with the entire system.
The dashboard GUI was first tested using a test Arduino script that would send out dummy values for all
of the metrics that would be sent from the sensors: speed, date, time, temperature, lat/lon positions, and
battery charge remaining. The Arduino script would repeatedly send out these dummy values to test that
the GUI was updating once every second and the application accurately placed the incoming values into
the correct slots. This test allowed the team to fix some small bugs in the code, and after a few rounds of
edits the GUI responded as desired: the values updated once every second and each feature had the proper
data values.
The next test was to have real-time data from the sensors sent from the Arduino to the Raspberry Pi GUI.
This test was conducted several different times under different conditions. One test tested the accuracy of
the GPS location and the speed when there was no motion. The data values were printed out and saved,
and then reentered into Google Maps to ensure that the position reading was adequately accurate. The
speed values were compared to the various changes of motion recorded by the user; this test aimed to see
if the noise floor for the signal was large enough to make the speed reading indicate the car was moving
when it was in reality stationary. Figure 66 shows the results of the speed accuracy test, demonstrating
that a speed value rounded to the nearest integer is sufficient to cancel out the stationary noise floor.
Figure 66: A Chart Showing the Speed Readouts Based on Different Modes of Walking
56
Another test tested the signal integrity, current map view, and accuracy of the position marking on the
map. The team carried the dashboard through Calvin’s campus, trying to walk as many sidewalks as
possible. The team walked close to building and through tighter spaces where the buildings may cause
signal interference. The team conducted this particular test twice: the first test lost the GPS signal for a
few minutes before it came back on and the GUI began to function normally again while the second test
never lost the GPS signal. The test that lost signal was on a cloudy day, which may have contributed to
the loss of signal. Both the current map view and accuracy of the position marking were found to be
functional and accurate in both tests: the current map view changed according to the section of the
campus map the tester was in and the position marking only had minor deviations from the marked paths
on the map. This deviation is most likely due to the fact that the GPS positional coordinates are being
converted from 5 decimal places of accuracy to integer accuracy in the mapping of the coordinates to the
corresponding pixel location on the image.
A final test tested the accuracy of the speed reading when driving and the position marking on the map.
The primary purpose for this test was to determine if the speed readings matched the true acceleration of
the vehicle and if there was any time delay of the speed readings. This test was conducted in De Zeeuw’s
car, with one person driving the car while the other held the dashboard and watched the readings. The
team drove around the campus roads, watching to the position marking to ensure the points were
smoothly following the path. The position marking was successful and demonstrated its functionality
when driving at average speeds for the Calvin Bolt (15~20 mph). The speed reading was tested by having
the driver shout out the speedometer readings on the car as the car accelerated while the passenger
watched the speed reading on the GUI to see how the two matched. The results of the test saw a 1~2
second delay in the speed shown on the GUI to the actual speed of the car. The team determined that this
was an acceptable delay since the data transfer process from the Arduino passes through many stages
before reaching the GUI on the Raspberry Pi.
Videos of the various tests performed can be found on the team’s website [25].
6.2 Primary Electrical System
The primary electrical system of the Calvin Bolt was tested before it was integrated into the vehicle. This
system includes the electric motor, motor controller, batteries, throttle potentiometer, and power switch.
The team successfully tested both the forward and reverse modes of the motor, increasing the speed of the
motor by moving the lever of the throttle.
6.3 Full Vehicle
The team planned to conduct a variety of tests on the full vehicle once it was completed, including tests
for the maximum speed, braking distance, acceleration time to top speed, steering ability, turn radius, ease
of use of the electrical system, and overall safety and comfort of the vehicle. Unfortunately, the team was
unable to conduct thorough testing of the vehicle due to time delays experienced both mechanically and
electrically.
57
The team was able to test the vehicle briefly on May 6, 2016, and videos of the team’s tests can be found
on the team’s website [25]. The team tested the vehicle in both forward and reverse, demonstrating that
the motor could successfully switch between the two directions. The team drove the vehicle around the
commuter parking lot, investigating both top speed and handling of the vehicle. The team estimates that
the vehicle hit a top speed of about 20 mph, which is within the team’s project requirement of a top speed
of 25 mph. The vehicle’s steering was easy to handle and was able to turn cleanly without any bumps in
the turn process. The brakes were not as powerful as the team had hoped, but the brakes did bring the
vehicle to a stop in the approximate location the driver had desired. The team riding in the vehicle
experienced a smooth ride as the road disturbances did not jostle the passengers around inside the vehicle.
The team sought to conduct more thorough tests on May 7, 2016, but as the team was slowing driving out
to conduct the tests, the steering wheel slightly popped out which locked the steering system and the
brakes were not functional. Since the steering and brakes could not be tested until the whole vehicle was
operational, those components would likely need some final adjustments after observing how the
components behaved when the vehicle was in operation. The team believes the brakes and steering are
simple fixes, but due to time constraints the team did not have time to repair the components to complete
more testing. As a result, the team was unable to test the acceleration time to top speed, turn radius, and
exact measurements for the maximum speed and braking distance.
On the night of the Senior Design Banquet and Open House on May 7, 2016 the team was able to obtain
some insight on the ease of use of the electrical system and overall layout and comfort of the vehicle. The
two power switches for the Raspberry Pi and Touchscreen were confusing to a majority of people, and in
the future the team would figure out a new way to provide power to the electronic dashboard that would
involve only one power switch. The team received a lot of positive feedback about the comfort of the
vehicle, voicing praise for the leg room, comfortable seats, and suicide doors. Overall, the team received a
lot of positive feedback about the layout and design on the vehicle, demonstrating that the team was
successful in creating an aesthetically pleasing vehicle that could provide more comfort to the passengers.
58
7 Business Plan
7.1 Market Competition
The small electric vehicle market is well established due to the increased demand for golf-cart like
vehicles in sports venues, university campuses, and senior living communities in addition to the
traditional gold course. The three main competitors for the Calvin Bolt are Club Car, E-Z-GO, and
Yamaha.
Club Car manufactures golf, utility, and transportation vehicles that can fulfill a variety of needs. Club
Car currently has about 40 base models in their stock, and is continuing to grow with an increased
demand for these types of vehicles. Accessories and other parts can be added to any Club Car to make it
customizable to the customer’s application.
E-Z-GO manufactures primarily golf carts with a line of personal vehicles that still maintain the golf cart
style and layout. E-Z-GO’s vehicles are primarily designed to carry people, lacking the hauling
capabilities of certain Club Car models. E-Z-GO offers additional parts and accessories as well, ranging
from audio systems to seating.
Yamaha is a manufacturer of a wide range of transportation vehicles, including speedboats, snowmobiles,
motorcycles, ATVs, and golf carts. Yamaha boasts a 6.7 horsepower A.C. motor in their electric golf cart
models, surpassing both E-Z-GO and Club Car, who have horsepower ratings of 4.4 and 3.3 respectively.
Just like Club Car and E-Z-GO, Yamaha offers a variety of additional parts and accessories to customize
the vehicle. For its electric golf cart line, only two person vehicles are available; a gas motor powers all
four-person vehicles.
The marketing strategy for Calvin Bolt is to create a vehicle that is a cross between a golf cart and a car,
making the vehicle more comfortable and accessible. In the case of mass production, the Calvin Bolt
would be marketed as a product that promotes accessibility for those who have mobility challenges while
maintaining a high aesthetic standard; the product would also be a cheap option for businesses looking to
have a larger capacity vehicle with a larger passenger seating space than a traditional golf cart. Table 4
lists the price points of the Calvin Bolt’s major competitors based on price research for a brand new cart.
Table 4: Competitor Prices for Electric Golf Carts
Competitor
Base Price
Club Car (4 seater)
$6,700
E-Z-GO (4 seater)
$7,500
Yamaha (2 seater)
$5,500
59
7.2 Breakeven Analysis
The costs for the materials and labor to construct the Calvin Bolt was researched and can be found in
Appendix H. The team estimated that mass production of the Calvin Bolt would produce 250 units per
year. The annual fixed and variable costs as well as the per-unit variable costs can be found in Table 5.
The break-even analysis found that 127 units must be sold for the company to start generating a profit.
Table 5: Estimated Fixed and Variable Costs for Production
Cost
Per Unit
Annual
Parts/raw materials (+10%)
$2,997.50
$749,375
Labor and Burden
$720
$180,000
Overhead
$500
$125,000
Factory
$150
$37,500
Total Variable Costs
$4,368
$1,091,875
Building Rent
Building Utilities
Building Operating Costs
Insurance
Engineering Staff (with benefits)
Welding Staff (with benefits)
Linemen Staff (with benefits)
Administration Staff (with benefits)
Marketing Staff (with benefits)
Finance Staff (with benefits)
Total Fixed Costs
Total Costs
Profit
Company
Contingency
Selling Price
Profit
-----------------------
$55,938.75
$34,309.1
$117,993.30
$100,000
$351,000
$236,250
$506,250
$94,500
$67,500
$67,500
$1,631,241.15
--35% margin
40% margin
20% margin
$17,288
---
$2,723,116.15
------$4,322,000
$1,598,884
60
8 Conclusion
8.1 Final Results
Throughout the academic year, Team 10 successfully designed and built a 4-person electric vehicle. This
was determined based on the fact that the project fulfilled all of the requirements laid out at the beginning
of the project, which were previously stated in section 2. While all specific project goals but one were
also met in the final product, the one goal that was not able to be met comes into play with the seasonal
outdoor usage. Team 10 originally desired to implement a front windshield to protect the driver and
passengers from precipitation and wind, this was not a feature that was possible to include in the final
design due to budget restrictions. This is something that the team would love to see implemented as future
work to the vehicle.
8.2 Project Reflection
The Engineering 339 and Engineering 340 courses, commonly referred to as ‘Senior Design,’ provided
immense opportunity for Team 10 to experience and learn skills necessary for projects and teamwork.
After completing the designs for the Calvin Bolt, the team took some time to reflect on the final designs
and contemplated aspects of the design that the team would do differently if given the chance to work on
a second prototype. The team learned valuable lessons about materials, manufacturing and design over the
course of the project, and this new knowledge gave the team insights about different alternatives that
could have been pursued.
In regards to materials, the team would still have picked aluminum as the frame material because of the
lightness the material offers. The team would have liked to have bought new sprocket gears and a higher
power DC motor.
In regards to manufacturing, the team would have designed the vehicle to be more easily manufactured.
The team would make sure all the angles and lengths of cut the team designed would be to the nearest
whole number in degree and inches. Also, the frame would have been designed with more appropriate
tolerances between parts, and construction wouldn’t begin until after all parts have been simulated.
On the electrical side of the project, the team would have integrated the electronic dashboard into the
vehicle’s main electrical system. The team would have accomplished this by adding more sensors tied
directly to the motors and batteries to give a more accurate representation of the current conditions of the
system. The team also would have considered making the charging system for the vehicle more userfriendly. Currently, the devices that need to be charged are spread out, forcing the user to remember to
charge multiple devices; in another design, the team would have centralized all of the devices that needed
to be charged to make it as simple to use as possible. In another design the team would also have spent
more time making the system waterproof. While some of the electronics were enclosed in cases that
would help keep most water out, most of the microelectronics were still exposed in some way which
would present problems if the vehicle was driven in rain. The team would have made sure all of the
electronics were protected better from water, while still maintaining the aesthetics of the vehicle.
61
Through this project, the team learned a valuable lesson about system integration, that while components
and smaller systems can work separately when tested and designed, the larger picture must be focused on
as well. A component is not successful unless it can be successful within the full system, which was the
case for the lighting system. While the lights were all designed and tested successfully before integration,
unfortunately, due to the time constraints at the end of the project, the team was not able to functionally
integrate the system into the prototype. There were scheduling setbacks at the end of the project that
caused there to only be about one day for the team to integrate and install all of the electronics into the
vehicle. The team learned a valuable lesson about the realities of prototyping and setting priorities for
certain components of a project.
On the aesthetics side of the vehicle, there were also multiple ways in which the final product differed in
how the team originally planned. Again, due to time constraints, the painting of the exterior did not turn
out how the team had hoped, but other components in the system were given a higher priority. Carpet was
placed in the interior, which was not originally planned, but gave the vehicle a very polished look with
which the team was very pleased.
The team also had to recognize that the final prototype was only the first attempt at the design, and in
reality multiple prototypes are built for a project of this type before a final product is reached. This project
experience gave the team valuable exposure to engineering projects, team dynamics, scheduling and
budgeting, communication, and more that will be translated to each member’s personal experiences and
careers to come.
62
9 Acknowledgements
Team 10 would like to acknowledge the following companies and individuals for their support, advice,
donations and overall assistance with the Calvin Bolt. Thank you for all of your help and generosity that
has made this project a success.
Digital Fabrication, Inc. - Cutting and welding of sheet metal
Harbor Steel - Donation of sheet metal
Grand Rapids Chair Company - Donation of seats
Signmakers, Ltd. - Donation of exterior decals
Temper - Donation of labor costs for cutting and welding of sheet metal
VMAX Tanks Battery Company and Abraham Ghaleb - Donation of two batteries and industry advice
Professor Randy Brouwer - Electrical advice and expertise
Professor Yoon Kim - Electrical advice and expertise
Professor Mark Michmerhuizen - Electrical advice and expertise
Professor Ned Nielsen - Team advisor
Professor Ren Tubergen - Industry advisor
Phil Jasperse - Manufacturing advice and expertise
Bob DeKraker - Parts and ordering
Michelle Krull - Administrative assistance
Calvin College Physical Plant - Painting facilities and vehicle transportation
Bob Doornbos - Industry advice
Jim VanderVeen - Industry advice
Andrew De Zeeuw - 2012/2013 Senior Design Team 13 - senior design advice and donation of Arduino
Michael De Zeeuw - Raspberry Pi/touchscreen case design
Mike Boluyt - Fabrication construction, use of woodshop, donation of console materials
Josiah Markvluwer - Welding assistance
Alltrax - Technical support and expertise with controller software troubleshooting
Friends and Family for their constant support and enthusiasm
63
10 Works Cited
[1] http://www.walmart.com/ip/TG-TEK-TGH1051-with-WiFi-10.1-Touchscreen-Tablet-PC-FeaturingAndroid-5.1-Lollipop-Operating-System-Black/49557130
[2] http://www.itechdeals.com/apple-ipad-2-with-wi-fi-16gb-black-2nd-generation-in-black.html?gclid=
CKCNnNmBqMwCFQyNaQodZfcANA
[3] http://www.bestbuy.com/site/samsung-galaxy-tab-a-7-8gb-black/4943611.p?id=bb4943611&skuId=
4943611&lsft=ref:212,loc:1&ksid=fe3d200c-6b88-4b9d-b2c41a0f1764dfc&ksprof_id=12&ksaff
code=pg8388&ksdevice=c&ref=212&loc=1
[4] Bourque, Brad. “Arduino vs. Raspberry Pi: Mortal Enemies, or Best Friends?”. DigitalTrends. 8
Mar. 2015. Web <http://www.digitaltrends.com/computing/arduino-vs-raspberry-pi/>
[5] “Raspberry Pi / PIFTS”. Adafruit. Web. <https://www.adafruit.com/categories/804>
[6] http://www.banggood.com/10_1-Inch-1366768-High-Definition-HD-Display-Module-Kit-ForRaspberry-Pi-p1036349.html?currency=USD&createTmp=1&utm_source=google&utm_medium
=shopping&utm_content=jude&utm_campaign=ele-xie-us
[7] http://i0.wp.com/makezine.com/wp-content/uploads/2015/09/IMG_26261.jpg
[8] Liang, Oscar. “Connect Raspberry Pi and Arduino with Serial USB Cable”. Web.
<https://oscarliang.com/connect-raspberry-pi-and-arduino-usb-cable/>
[9] Liang, Oscar. “Raspberry Pi and Arduino Connected Over Serial GPIO”. Web.
<https://oscarliang.com/raspberry-pi-and-arduino-connected-serial-gpio/>
[10] Liang, Oscar. “Raspberry Pi and Arduino Connected Using I2C”. Web.
<https://oscarliang.com/raspberry-pi-arduino-connected-i2c/>
[11] Cawley, Christian. “Pi to Go? 3 Ways of Powering a Raspberry Pi for Portable Projects”.
MakeUseOf.com. 28 May 2015. Web. <http://www.makeuseof.com/tag/pi-go-x-ways-poweringraspberry-pi-portable-projects/>
[12] “Compute Module Hardware Design Guide”. Raspberry Pi. Web. <https://www.raspberrypi.org/
documentation/hardware/computemodule/cm-designguide.md>
[13] “Temperature Range for Arduino” Arduino Forum. 03 May 2010. Web. <http://forum.arduino.cc
/index.php?topic=27228.0>
64
[14] BalearicDynamics. “Raspberry Pi Touch Screen Frame and Case Assembly Guide”. Instructables.
Web. <http://www.instructables.com/id/Raspberry-PI-Touch-Screen-Frame-and-Case-Assembly
-/?ALLSTEPS>
[15] “Raspberry Pi 7” Touch Screen Display Case Assembly Instructions”. ModMyPi. 2 Sept. 2015.
Web. <http://www.modmypi.com/blog/raspberry-pi-7-touch-sreen-display-case-assembly
-instructions>
[16] “Case for Touchscreen 7” - Raspberry Pi 2B - Cam”. Thingiverse. 5 Dec. 2015. Web.
<http://www.thingiverse.com/thing:1164446>
[17] “RPi Debian Auto Login”. eLinux.org. 24 Feb. 2013. Web. <http://elinux.org/RPi_Debian_Auto_
Login>
[18] “How to Autostart Apps in Rasbian LXDE Desktop”. RaspberryPiSpy. 3 May 2014. Web.
<http://www.raspberrypi-spy.co.uk/2014/05/how-to-autostart-apps-in-rasbian-lxde-desktop/>
[19] “1.5. Basics of How Operating Systems Work”. Web. <http://faculty.salina.k-state.edu
/tim/ossg/Introduction/OSworking.html>
[20] Christensson, Per. "Multithreading Definition." TechTerms. Sharpened Productions, 26 September
2008. Web. 24 April 2016. <http://techterms.com/definition/multithreading>
[21] https://github.com/eliben/code-for-blog/tree/master/2009/plotting_data_monitor
[22] http://www.buggiesunlimited.com/images/products/7240.jpg
[23] http://www.eztsk.com/RegularTurnSignalKit.html
[24] “How to Add Turn Signals and Wire Them Up”. HowToBuildHotRods.com. Web. <http://www.
how-to-build-hotrods.com/turn-signals.html>
[25] http://www.calvin.edu/academic/engineering/2015-16-team10/ **
** If Team 10’s website is no longer available, please contact Christine De Zeeuw at christine@dezeeuw.us
65
11 References
https://www.parallax.com/product/28509
https://www.parallax.com/sites/default/files/downloads/28509-PAM-7Q-GPS-Module-ProductGuide-v1.0_1.pdf
http://playground.arduino.cc/Tutorials/GPS
https://www.youtube.com/watch?v=vQixM9TTUyU
https://www.youtube.com/watch?v=Dmo8eZG5I2w
http://doc.qt.io/qt-4.8/qgraphicsscene.html#public-functions
https://pythonprogramming.net/application-structure-pyqt-tutorial/
https://nikolak.com/pyqt-qt-designer-getting-started/
https://wiki.python.org/moin/PyQt/Compass%20widget
http://it.toolbox.com/blogs/enlightenment/pyside-tutorial-using-qt-designer-with-pyside-66012
https://wiki.qt.io/QtCreator_and_PySide
https://quaxio.com/arduino_gps/
http://arduiniana.org/libraries/tinygps/
http://www.instructables.com/id/ARDUINO-TEMPERATURE-SENSOR-LM35/
http://www.ti.com/lit/ds/symlink/lm35.pdf
http://www.makeuseof.com/tag/pi-go-x-ways-powering-raspberry-pi-portable-projects/
http://www.amazon.com/Innogie-10400mAh-AlienPower-Portable-Smartphones/dp/B00WU487J
A/ref=pd_sim_107_2?ie=UTF8&dpID=41tMCjQjOUL&dpSrc=sims&preST=_AC_UL160_
SR160%2C160_&refRID=1B9F04FMZ38BJW44TFP4
https://www.raspberrypi.org/blog/the-eagerly-awaited-raspberry-pi-display/
https://github.com/raspberrypi/documentation/tree/master/hardware/display
http://www.eclipse.org/downloads/index.php?show_instructions=TRUE
https://www.rose-hulman.edu/class/csse/resources/Eclipse/eclipse-python-configuration.htm
http://www.gearbest.com/led-strips/pp_229877.html
https://www.arduino.cc/en/Guide/Windows#toc4
http://www.electriccarpartscompany.com/Curtis-br-2-Wire-PB-6-Pot-Box-Throttle-br-EVController-Component_p_241.html
http://www.evdrives.com/product_p/thr-pb6.htm
http://www.calvin.edu/academic/engineering/2014-15-team04/documents/FINAL_REPORT.pdf
http://www.calvin.edu/academic/engineering/2013-14-team15/files/docs/Team15_Report.pdf
http://stackoverflow.com/questions/21692028/pyqt4-constantly-updating-text
https://wiki.qt.io/Qt_Serial_Port
https://github.com/eliben/code-for-blog/tree/master/2009/plotting_data_monitor
https://github.com/mba7/SerialPort-RealTime-Data-Plotter
https://wiki.python.org/moin/PyQt/Compass%20widget
https://www.kiwi-electronics.eu/modmypi-touchscreen-behuizing-standaard
http://www.thingiverse.com/thing:1021025
http://www.modmypi.com/blog/raspberry-pi-7-touch-sreen-display-case-assembly-instructions
http://www.thingiverse.com/thing:1164446
http://www.instructables.com/id/Raspberry-PI-Touch-Screen-Frame-and-Case-Assembly/?ALLSTEPS
66
https://www.surpluscenter.com/Electric-Motors/DC-Gearmotors/DC-Gearmotors/62-RPM-12-VD
C-BOSCH-GEARMOTOR-5-1832.axd
http://www.gearbest.com/led-strips/pp_141180.html
http://www.gearbest.com/led-strips/pp_229877.html
https://www.etrailer.com/Trailer-Lights/Optronics/MC32RB.html
http://manuals.harborfreight.com/manuals/37000-37999/37349.pdf
http://pinouts.ru/visual/USB.jpg
http://www.recantha.co.uk/blog/?p=1103
https://www.raspberrypi.org/forums/viewtopic.php?p=736227#p736227
http://www.hobbytronics.co.uk/arduino-float-vars
http://www.alltraxinc.com/files/Doc113-002-C_XCT-SRX_Toolkit_Manual.pdf
http://www.alltraxinc.com/files/DOC113-001-D_OP-SPM-SPB-OPERATORS-MANUAL.pdf
http://www.facstaff.bucknell.edu/mastascu/elessonshtml/basic/basic6pe.html#Batteries
http://hypertextbook.com/facts/2002/RaymondTran.shtml
http://www.vias.org/physics/example_4_4_03.html
http://www.school-for-champions.com/science/work_energy.htm#.Vw7jPPn48dU
http://www.powerstream.com/battery-run-time-calculator.htm
https://www.lens.org/images/patent/WO/2009059168/A2/WO_2009_059168_A2.pdf
http://www.techrepublic.com/blog/10-things/10-things-you-should-know-about-usb-20-and-30/
67
12 Appendices
Table of Contents
A.
B.
C.
D.
E.
F.
G.
H.
Daily Schedule for the Final Month
Project Budget
Motor Calculations
Motor Specification Drawing
Motor Controller Program Images
SPM 48400 Motor Controller Wiring Diagram
Frame Design Drawings
Business Plan Production Cost Estimates
68
Appendix A – Daily Schedule for the Final Month
Schedule During Open Machine Hours
March
Monday 28 – Finish Front Suspension Mounts
th
Tuesday 29 – Weld Front Suspension and Tack all vertical beams
th
Wednesday 30 – Weld Back Tubing
th
Thursday 31 – Continue Welding Back Tubing, Start on Front Tubing
st
April
Friday 1 – Continue Welding Front
st
Monday 4 – Continue Welding Front
th
Tuesday 5 – Finish Welding Front, Start on Roof, Vince is speaking at seminar from 3:30 to 4:30
th
Wednesday 6 – Continue on Roof
th
Thursday 7 – Finish Roof, Start on Cross Members
th
Friday 8 – Complete Frame or Continue Cross Members till Frame is completed
th
Monday 11 – Completed Frame – Get Ready to Transport to Design Fab to get Sheet Metal Cut and Sheets
Welded
th
Tuesday 12 – Transport Frame and Metal, Start on Seat Frames (Time of completion 3 to 4 days)
th
Wednesday 13 – Vince is gone for SAE Conference, Continue on Seat Frames
th
Thursday 14 – Finish Front Seat Frame. Start on Back Seat Frame
th
Friday 15 – Continue on Back Seat Frame
th
Monday 18 – Continue/Finish on Back Seat Frame
th
Tuesday 19 – Finish Back Seat Frame, Start on Doors
th
Wednesday 20 – Continue on Doors
th
Thursday 21 – Finish Doors (Structure) and Attach Doors to Frame and Figure out how to stick panels on
doors (glue or silicon), Mechanism to Latch Doors
st
Friday 22 – Start Bondoing Car
nd
Monday 25 – Finish Bondoing Car
th
Tuesday 26 – Send Vehicle in for Paint, Create Mechanism to Latch Doors + Make Sure Automatic Seats
Work and are ready to be put into the car after paint.
th
Wednesday 27 – Get Car Back from Paint/Make sure electrical systems work
th
Thursday 28 – Get Car Back from Paint hopefully and install all electrical components + stickers / detailing
stuff with spray paint and install seats.
th
Friday 29 – Keep on installing….. Make sure door latches work… Make sure everything works.
th
May
Last Week – Test Runs and Report
May 2nd -- Final In-Class Oral Presentation
May 7th -- Senior Design Openhouse, Banquet and Presentation Night
69
May 9th -- Final Website Upgraded
May 11th -- Final Design Report Due
Not During Machine Shop Hours (Things that need to get finished or bought)!





















Detailing Work and Getting Stickers Ready
Connect Rack and Pinion System
Seat Motor Installed on Front Seat
Buy Pedals
Brake Pedal Mechanism
Gas Pedal Mechanism
Steering Mechanism
3D Print Dashboard Holder
Front Suspension Angle and Adjustment
Back Suspension (Done)
Back Tubing Alignment
Front Tubing Alignment
Connect Rods (Pillars)
Buy Wood for Floor
Buy Wood for Rear
Buy Windshield
Buy Canvas for Roof
Buy Paint for Physical Plant
Get Sheet Metal cut list Updated and Sent to Design Fab
Buy Gears for Transfer Case to Motor Efficiency
Get Stickers Designs to Professor Nielsen
70
Appendix B – Project Budget
71
Appendix C – Motor Calculations
72
73
74
75
76
Appendix D – Motor Specification Drawing
77
Appendix E – Motor Controller Program Images
78
Appendix F – SPM48400 Motor Controller Wiring Diagram
79
Appendix G – Frame Design Drawings
Original Frame
Revision A
-
Replaced all bent tube with
straight tube to make assembly
easier.
Revision B
-
80
Converted line model to 3D
tube model
Eliminated cross-members
from roof
Eliminated B Pillars
Increased detail in front end
Revision C
-
-
Replaced base with square
tubing to increase the
strength of the frame
Added support member in
rear wheel well
Revision D
-
Removed seat frame
support members in center
of frame
Revision E
-
81
Modified front suspension
area of frame to
accommodate the front
suspension design
Revision F
-
Converted members on top
of rear wheel well to square
tube to increase the strength
of the frame
Revision G
-
Added support members for
rear suspension
Revision H
-
82
Added additional support
members for rear of frame
Appendix H – Business Plan Production Cost Estimates
Item
Building Rent
Building Utilities
Building Operating Costs
Insurance
Engineering Staff
Administration Staff
Marketing Staff
Labor and Burden
Annual Units Sold
Cost
$3.75/sq. ft. for 14,917 sq. ft.
$2.30/sq. ft. for 14,917 sq. ft.
$7.91/sq. ft. for 14,917 sq. ft.
$100,000 per year
3-5 engineers @$65,000/yr each
1 @ $70,000/yr
1 @ $60,000/yr
$12.50/hr per worker – 8-10 workers
250
83