Automated Welding System for PVC Roof Membranes

Project Team 43
Senior Design
(MEM491)
Automated Welding System for PVC Roofing Membrane
Final Report
13th
May 2015
Team Members:
Tyler Darrah
Justin Dempsey
Elliot Farquhar
Joseph O'Brien
Robert Stricek
Advisor: Dr. Bor-Chin Chang
Sponsor: SFS intec
Mechanical Engineering and Mechanics
Drexel University, Philadelphia, PA 19104
Abstract
The installation of a flat roof employs fastening together a layer of corrugated steel sheet, rigid
foam insulation, and a weatherproof thermoplastic membrane. Initially, adhesive-coated metal plates are
placed atop the insulation and fasteners are driven through them to secure the insulation. The membrane
is then placed down and secured through a non-destructive bonding process utilizing induction heating to
fuse together the metal plates and membrane. Issues arise with bond strength inconsistencies and excess
job duration due to the tedious manual nature of existing tools. The senior design team had set out to
eliminate these inconsistencies by semi-automating the plate locating and welding processes, thus
improving both job quality and customer satisfaction. The senior design team developed a strong,
efficient, and cost effective prototype which centered on the non-destructive induction heating system. As
critical functions were automated, secondary systems were then integrated to further improve the
performance and capabilities of the device.

Table of Contents
I. Introduction ............................................................................................................................................. 1
1.1 Background ........................................................................................................................................ 1
1.2 Stakeholders and Needs ..................................................................................................................... 1
1.3 Mission Statement.............................................................................................................................. 2
II. Methods .................................................................................................................................................. 2
III. Design Description................................................................................................................................ 2
3.1 Specifications...................................................................................................................................... 2
3.2 Concepts ............................................................................................................................................. 3
3.3 Concept Evaluation............................................................................................................................ 4
3.4 Embodiment........................................................................................................................................ 4
3.5 Detailed Design .................................................................................................................................. 5
3.5. A Logic Design and Programming ........................................................................................ 5
3.5. B Frame.................................................................................................................................... 6
3.5. C Drivetrain ............................................................................................................................. 8
3.5. D Sensors.................................................................................................................................. 9
3.5. E Sensor Array......................................................................................................................... 9
3.5. F Induction Coil..................................................................................................................... 10
3.5. G Induction Coil Sensor........................................................................................................ 11
3.5. H Linear Actuator and Ultrasonic Sensor............................................................................ 12
3.5. I Pressure Roller .................................................................................................................... 12
3.5. J Control System .................................................................................................................... 13
3.5. K Detailed Prototype Pictures ............................................................................................... 14
3.6 Prototype Verification and Testing.................................................................................................. 14
III. Context and Impact............................................................................................................................ 17
4.1 Economic Impact ............................................................................................................................. 17
4.2 Environmental Impact ..................................................................................................................... 17

4.3 Social Impact.................................................................................................................................... 18
4.4 Ethical Impact.................................................................................................................................. 18
IV. Project Management .......................................................................................................................... 18
5.1 Team Organization ........................................................................................................................... 18
5.2 Schedule and Milestones................................................................................................................... 18
5.3 Project Budget................................................................................................................................... 19
V. Discussion.............................................................................................................................................. 19
VI. Summary and Conclusion.................................................................................................................. 20
VII. Future Work...................................................................................................................................... 21
VIII. References ........................................................................................................................................ 22
V. Appendix .............................................................................................................................................. 23

List of Figures
Figure 1: Roof Layers Illustration .......................................................................................1
Figure 2: Von Mises Stresses with Footstep Load ..............................................................6
Figure 3: Shear Stresses with Footstep Load ......................................................................6
Figure 4: Von Mises Stresses Holding the Frame ..............................................................7
Figure 5: Shear Stresses Holding the Frame .......................................................................7
Figure 6: Von Mises Stresses Holding One Leg .................................................................7
Figure 7: Shear Stresses Holding One Leg .........................................................................7
Figure 8: Von Mises Stresses Pushing with 30lbs ..............................................................7
Figure 9: Shear Stresses Pushing with 30lbs ......................................................................7
Figure 10: Front Wheel .......................................................................................................8
Figure 11: Rear Motor Assembly .......................................................................................8
Figure 12: Pillow Block Bearing ........................................................................................8
Figure 13: Proximity Sensor AT1-AN-3A .........................................................................9
Figure 14: NPN Output Configuration ...............................................................................9
Figure 15: Coil Housing.....................................................................................................11
Figure 16: Picture of Ultrasonic Sensor ............................................................................12
Figure 17: Pressure Roller Drawing .................................................................................13
Figure 18: Front Left Side View of Prototype ..................................................................14
Figure 19: Rear Right Side View of Prototype .................................................................14
Figure 20: Right Side View of Prototype .........................................................................14
Figure 21: Prototype Electrical Housing View .................................................................14
Figure 22: Test Section Setup............................................................................................14
Figure 23: Prototype Executing Test ................................................................................15
Figure 24: Pull Test Setup .................................................................................................15
Figure 25: 6s Weld Time ..................................................................................................15
Figure 26: 10s Weld Time ................................................................................................15
Figure 27: 12s Weld Time .................................................................................................15
Figure 28: Detection Time Results ...................................................................................16
Figure 29: Weld Strength Results .....................................................................................16
Figure 30: Methods Approach ..........................................................................................28
Figure 31: Concept 1..........................................................................................................29
Figure 32: Concept 2..........................................................................................................29
Figure 33: Concept 3..........................................................................................................30
Figure 34: Induction Heating Uniformity..........................................................................30
Figure 35: Thermal Imaging Test Apparatus.....................................................................31
Figure 36: Sensory Array Spacing.....................................................................................31
Figure 37: Electrical Wiring Diagram ...............................................................................34
Figure 38: Final Arduino Program.....................................................................................35

List of Tables
Table 1: Material Properties ................................................................................................7
Table 2: Variables Definitions...........................................................................................10
Table 3: Linear Actuator Parameters ................................................................................12
Table 4: Ultrasonic Sensor Specifications ........................................................................12
Table 5: Summary of the Arduino Mega 2560 .................................................................13
Table 6: Various Heating Durations Quantitative and Qualitative Results .......................15
Table 7: Overall Comparison.............................................................................................16
Table 8: Project Schedule Gantt Chart...............................................................................23
Table 9: Bill of Materials...................................................................................................24
Table 10: Needs and Specifications List............................................................................27
Table 11: Prototype Testing Data ......................................................................................32
Table 12: ISO Weld Testing Data......................................................................................32
Table 13: Concept Decision Matrix...................................................................................33

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I. Introduction
1.1 Background
In the commercial flat roofing industry, there are a variety of systems that can be used to protect a
roof from the elements. These systems include tar and ballast, expandable foam, and mechanical
attachment. Focused on trying to capture this growing market, the sponsor asked the senior design team to
come up with an innovative solution to address the challenges of mechanical attachment. The process
begins with the fastening of a steel deck onto purling’s that run the length of the roof. Insulation is then
laid on top of this decking. Adhesive-coated metal plates are placed atop the insulation and
fasteners are driven through into the steel decking below. A layer of PVC or TPO membrane is then
placed on the roof, thus hiding the resin coated plates. A device must then be used to not only locate these
plates but also heat the resin in a way which does not destroy the membrane. After heating the plate, a
magnetic heat sink is placed on the plate to cool the resin and complete the adhesion of the membrane to
the plate surface. These layers can be seen in detail in Figure 1 below.
Figure 1: Roof Layers Illustration [1]
In today’s market there are only two systems which perform the task of locating and heating these
metal plates. Both devices utilize induction heating but perform this task with varying accuracy. The
sponsor’s device, for example, will not perform the induction process on fastener plates which are off-
centered from the induction coil whereas the competitor’s device will perform the induction process on
plates inside a much larger induction coil perimeter. Though the sponsor’s tool ensures maximum bond
strength, it exhibits challenges when positioning the induction coil. On the other hand, the other device is
less taxing on the user but can be less consistent when it comes to the overall bond strength of the welds.
Another flaw both of these devices possess is that the user must tarnish (mark) the roof in order to
determine the general plate locations before positioning the device to perform the weld.
1.2 Stakeholders and Needs
The main needs that the senior design team sought to meet, indicated by the sponsor, were finding
plates underneath the membrane, heating the plates without damaging the membrane, and reducing or
eliminating the tedious manual nature of the overall process all while maintaining the accuracy and
quality of the sponsor’s current device. In an effort to capture more of the market, the design team took
into consideration the needs of those who would be using this device on a daily basis. Their main
concerns were user friendliness, durability, and job time savings. Lastly, flat roof building owners were
surveyed for their perspective on creating a new device. The outcome was to minimize the amount of
marking or scuffing that needs to be done to their new roofs. These stakeholders and their needs can be
found more in depth in Table 10 in Appendix B.

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1.3 Mission Statement
Our mission, as a design team, was to improve the mechanical attachment of roofing membrane
by creating a working proof of concept prototype that addresses as many priority one needs as possible. In
the end, this prototype would provide enough evidence to convince the sponsor to further pursue the
project into the next developmental stage.
II. Methods
The engineering method implemented for this project was a condensed version of the
methodology outlined by Ulrich and Eppinger [2]. As illustrated by the framework shown in Figure 30
Appendix B, the first step was to define the problem. Next, the design team determined the goals of the
project. Minimally, the design team hoped to develop an improved design of the current product but
ultimately agreed with the sponsor to develop a completely new device. With the ground work laid, in-
depth product research and background information was gathered in order to gain a full understanding of
the technologies available. Stakeholders were then polled for their opinions on what they needed to have
in a commercial flat roofing tool. Each need was matched with a quantifiable specification to ensure the
solution adequately agreed with the stakeholder requirements. Once multiple concepts were developed an
evaluation matrix had been used to determine which concept best coincided with the determined needs
and specifications. Lastly, a virtual and physical prototype was then constructed which would be put
through testing and data recording for performance evaluation.
Engineering principles utilized for this project included; basic thermodynamics, static and
dynamic equations, geometric analysis, computer logic analysis, circuit analysis as well as design, ethics,
and economics. Engineering tools include two and three dimensional CAD software, FEA simulation
packages, computer programming software, as well as various data and documentation organization
software.
III. Design Description
3.1 Specifications
In order to provide a device which addressed the sponsors concerns of accuracy and quality, the
design team worked with the sponsor to outline basic specifications paralleling their current device’s
capabilities. Of the needs which relate to accuracy and quality, the most important are distance from
center, heating temperature, and load strength. The distance from center is refereeing to the distance the
center of the induction coil is away from the center of the membrane plate being heated. A half inch was
determined as a nominal value due to sponsor data and results from thermal image tests performed in the
winter term. At this value, the strength of the bond is still within the acceptable limits but it is not as
strong as when the offset is zero. Though the sponsor’s tool does not perform a weld unless this value is
zero, the competitor’s tool claims that strong adhesion can still be achieved an inch off center. The
heating temperature metric was determined by SFS data which stated that 225 °C was the optimum
temperature for heating. The last specification describes the amount of tensile load a plate membrane
bond can withstand before failure. In order to ensure viable data, the speed of the pull would have to be
set to 2 inches per minute, a standard determined by Factory Mutual (FM). At this speed, the bonded
plates would then have to reach a load of at least 583lbf. If the prototype did not meet the load of the
sponsor’s current device, at the speed specified, then this product would have very little hope of gaining
traction in the industry.
Concerning the customer needs, most of these specifications came from interviews with
contractors who have had experience using the sponsor’s current device. Looking at the time
specifications, most are not concrete numbers but are instead percentages. This was done on purpose due
to the extreme variability which exists on job sites. These variables include user familiarity with the tool,
number of plates on a roof, plate patterns and spacing, and weather. To address durability, the impact and
load values of 50 lbf and 200 lbf were chosen by the design team to mimic an average user kicking,
standing, or falling onto the device. Ergonomics was also a concern as per interviewed users conveyed to
the design team. A 50 pound maximum weight limit, for example, was determined due to the limitation of

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the amount of weight that can be carried around a job site. Though independent operation was not a key
focus for this iteration of the prototyping process, some thought was put into the power consumption of
the device. In order to save on consumer cost, the design team wanted to create a device which ideally
operated on 120VAC, which is typically available from a jobsite generator or standard electrical U.S.
electrical outlet.
3.2 Concepts
After researching alternative sensing, heating, and navigating methods in the fall term, three basic
concepts were developed to address the priority one needs of the sponsor. Before all else, the device had
to be able to locate and heat the membrane plates. The designs then focused on meeting the priority one
needs of the customers such as job time reduction, durability, and membrane appearance. All other
secondary and tertiary needs were to be addressed after these key functionalities were met. The following
concept ideas focus on these key functionalities but address them with varying autonomy. After
discussions with the sponsor and various customers, the senior design team felt that it was both
impractical and extravagant to propose a fully autonomous device. Contractors, for example, like the
control a manual device grants to the user but dislike the time the manual device detracts from performing
other tasks. However they also want simplicity in the tools with which they use to complete the job.
Creating a fully autonomous device, in theory, would be simple to use and save time but would not grant
the user any control over the device.
Concept 1, seen in Figure 31 in Appendix B, is a manual device similar to that of the sponsor’s
device. This concept utilizes four wheels, two of which are connected together via a solid axle on the
front of the device. Analogous to a lawnmower, the device would track fairly straight and require minor
physical inputs to correct deviation. On the front of the device a sensor array would be mounted to
indicate to the user the general location of the plate horizontally and vertically in front of it. Inside the
square frame, a large induction coil would be mounted to heat the membrane plates. The larger coil
diameter, in conjunction with a higher power and frequency setting, should eliminate the need for precise
positioning of the device. This, however, would need to be confirmed in the winter term due to the high
inconsistency of the magnetic field strength. It is important to note that both the sensor array and
induction plate are not flush against the surface of the membrane. This is done to allow the plates the
ability to pass under the device as well as account for multiple plate orientations. By having the induction
coil free floating, the device would be able to heat plates driven in on an angle or too far in without
requiring the user to awkwardly position the device flush with the membrane plate surface. The
effectiveness of the induction heating, given angle and depression into the insulation, would also need to
be tested in the following terms.
Concept 2, seen in Figure 32 in Appendix B, utilizes the same frame, wheel, and sensor array
design as concept 1. One difference is that the forward mounted sensor array communicates with a
microprocessor which records the lateral location of the plate. This information will then be used to
physically move the center of the induction coil to the horizontal location of the plate via a linear
translation system. After translating the coil, an encoder will then record the distance the device travels as
the user attempts to position the device. Given the geometry of the device, the vertical difference between
the plate location and the center of the induction coil can be calculated. This calculated distance will then
be subtracted by the distance the encoders are recording until the difference becomes zero. Another key
difference is that the coil diameter of this design is much smaller than that of the first design. Instead of
using the coil to cover a large area, the translational system accounts for some of the area which the coil
needs to reach. Given the design teams research findings in the fall term, smaller coils produced more
even heating distributions. Just like concept 1, both the coil and the sensor array are raised from the
membrane surface.
The last concept, seen in Figure 33 in Appendix B is the most autonomous option. Unlike the
previous concept, this design requires two electric motors to drive the device instead of a human. Again,
the plate position and distance traveled will be recorded and sent to the microprocessor. Instead of
relaying this information to the user via a LED array or LCD screen, the information will be converted

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into a power setting the motors will output. Utilizing the same solid front axle helps to ensure the device
will track in a straight line but proper consideration will need to be taken when deciding upon the drive
motors. These motors will have to be powerful enough to provide the moment needed to correct small
course deviations. The induction coil is even smaller than in the previous design given the increased
accuracy of the control system.
3.3 Concept Evaluation
The first concept had been the least favorable option with respect to the needs and specifications
listed in Figure 31 in Appendix A. Though the device fundamentally would find and heat the plates, the
accuracy of the device would be questionable. Due to its larger size it would require not only more power
but also would be harder for the user to determine if the plate was near the center. One positive aspect is
that the device would ultimately be the fastest in overall job time. Again, due to its size, the coil would
ultimately take longer to heat the plate. This device not only gives the user the control they want but it
also is simple. This simplicity leads to better durability, strength, and user friendliness.
The second concept was determined to be the nominal favorite. This device would be capable of
achieving more accurate positioning due to the linear actuator and distance monitoring. With a better
positioning system the coil would be made smaller, which would save energy as well as improves heating
consistency. This device would become heavier, however, with the additional components and would
have a few more sensitive and weak components. With the added accuracy comes a price in time savings.
Given enough of a sample size, the accuracy would prove its worth versus the manual concept.
The last concept was the most autonomous. This device would be the most accurate but would
also be the weakest in terms of durability. The additional sensors make it easier and faster for the device
to locate the center of each plate as compared to the manual devices. The accuracy also provides the
sponsor the satisfaction of consistent replicable results. This device however does not grant the user the
ability to maintain physical control and may become more complicated than the other options. After
discussions with the sponsor, however, it was determined to pursue this concept. Added time and energy
would have to be put in to ensure these concerns were addressed. Table 13 in Appendix B shows the
decision matrix the design team used to help finalize the decision.
3.4 Embodiment
The initial prototyping began as an idea generating session in which each team member discussed
possible designs and features of the proposed device. The materials and components to be used would be
of standard, readily available, sizes and off frame in which each other component could be easily
attached. A CAD model was constructed utilizing Creo Parametric software, that of which each feature
could be individually designed and added to the overall design assembly later. Once the general CAD
model was developed, a finite element model was constructed to simulate the various loading conditions
that the prototype frame may encounter. The results of these simulations are outlined in the frame section
of the Detail Design. The team then moved on to physical prototyping of other components. First
prototyping` began with the induction coil system. This consisted of dismantling an induction cooking
device and obtaining full control of the heating capabilities through use of an existing circuit board. The
control board was examined, each circuit function was experimentally determined to allow operation via a
microcontroller later, and an induction coil enclosure was constructed out of insulated PPO plastic. Once
functioning with the microcontroller, the induction coil consistency and temperature capabilities were
tested through use of thermal imaging equipment. An example of the uniform heating results of the tests
and apparatus can be observed in Figures 34 and 35 in Appendix B.
Next, the team measured, cut, and welded members of the aluminum frame, and pre-drilled holes
so components, such as the motors, linear actuator, and sensors could be mounted to the frame. An
adjustable PVC tubular arm was constructed to attach the induction coil to the linear actuator, and
aluminum brackets were made for the rear roller. Miscellaneous machine shop and fabrication equipment,
such as a band saw, drill press, manual mill, and many hand tools, were also utilized in the physical
prototyping. The last physical prototyping was the electronics and control system. Initially, the team used

5
temporary breadboards, wire connectors, and a cardboard box to develop a functioning control system.
The electronics were then wired, soldered, and mounted inside an ABS electrical cabinet. The electronics
enclosure was completed with sealed grommets, cooling fans, and shelving to organize all of the control
system components to one centralized location.
3.5 Detailed Design
The team’s design focuses on providing a physical proof of concept prototype that can perform
necessary time consuming tasks autonomously, thus allowing for a more efficient welding process. The
prototype consists of a rigid aluminum rectangular frame with four vertical legs. Two of these legs were
used to attach motors and rear wheels. The front wheels are connected together via a solid axle, assisting
the device with maneuvering forward in a straight path. An array of sensors is mounted to the front of the
device to perform the task of providing information to the microcontroller pertaining to the location of a
detected metal plate. A conventional induction hot plate was utilized as the welding tool for the prototype.
The induction coil is separated from the other components and mounted to a linear actuator beneath the
center of the frame. This actuator in combination with an ultrasonic sensor allows the induction coil to
physically move, within a certain distance, to get as close to the center of the detected plate as possible
based solely on the initial front senor array detection. One additional sensor was designed to be placed at
the center of the induction coil. This sensor is used to improve the positional accuracy of the induction
coil. It marks the endpoints of the detected plate and uses the points to locate and position itself directly
atop the center of the metal plate before performing the weld. The entire system of electrical and
mechanical components is controlled by a microcontroller. The control system is also designed to allow
for operator input specifically pertaining to the number of welds that should be performed simultaneously.
The overall design is meant to be easily adaptable and repairable as well as easy to use while still
maintaining cost efficiency.
3.5. A Logic Design and Programming
A very significant aspect of this design and proof of concept prototype is the overall logic for
exactly how the device operates. The logic needed to be carefully considered and designed such that the
device would operate as desired. The exact logic for how the prototype operates is as follows; the operator
initially places the prototype at the start of a row of un-welded metal plates and squares up the vehicle to
ensure straight travel by turning on the laser attached to the front of the device. Once the vehicle is
squared up, the operator then specifies the total number of plates that he/she would like to weld within the
row. The prototype is then powered on through pressing the “ON” button on the wireless remote to
activate the power strip and supply power to the device. The prototype will then begin rolling forward at a
speed of approximately 0.5 ft/second. While the vehicle is moving forward, the front sensor array
containing seven sensors is looking for a metal plate beneath the thermoplastic membrane. Upon
detection of metal by the front sensor array, the specific combination of sensors that has detected the
metal plate relays that information to the microprocessor which then initiates the ultrasonic sensor and
linear actuator to position the induction coil accordingly. The wheels stop moving until the ultrasonic
sensor indicates that the linear actuator has moved to the proper position. The vehicle then begins moving
forward once again but an additional sensor located inside the induction coil housing at the center of the
induction coil is waiting to detect the already located metal plate. Once the center sensor detects the plate,
it activates the encoders on the rear motors to begin recording the distance traveled. Once the center
sensor no longer detects the plate, the motors stop and the final distance traveled is recorded. The motors
then reverse direction and begin moving backward at a slower speed of approximately 0.4 ft/second. The
motors stop moving once the distance traveled in reverse is exactly half of the distance value recorded by
the encoders when the center sensor was detecting metal and the motors remain off at this point until the
weld is performed.
The induction coil is now in a position where it is centered over the plate vertically, but not
horizontally. The induction coil is then centered horizontally through the adjustment of the linear actuator.
While the center sensor is detecting metal, the linear actuator begins to move to the left until the center

6
sensor stops detecting metal. At this point in time the linear actuator stops moving and records the value
that the ultrasonic sensor is reading. This ultrasonic reading is the left edge of the vertical center of the
metal plate that needs to be welded. The linear actuator then adds exactly 5.5 centimeters (plate radius) to
the recorded ultrasonic value and moves back to the right until the ultrasonic sensor reading is equal to the
left edge of the plate plus 5.5 cm. The induction coil is now fully centered over the located metal plate
and is ready to perform the weld.
The induction coil is then powered on and remains on for a 10 second interval. This ensures that a
strong sufficient weld is created between the membrane and metal plate. After the welding process has
been completed, the total number of welds is increased by one and the entire process repeats until the total
number of welds is equal to the total number of plates specified by the operator during the initial setup.
An Arduino Mega was chosen to drive the control system for the prototype and the code created to
replicate this logic is shown in Figure 38, Appendix B.
3.5. B Frame
The frame functions as the platform for which all other components come together and forms the
functional prototype. The cross-sectional area of the frame had been estimated to be 17”x22” to fit a 15”
linear actuator to the prototype, offering 10” of lateral translation for the heating coil. The 22” length
enables placement of the front axle, rear drive motors and heating coil housing completely within the
body of the prototype with some excess room for improvement initiatives described in Section 7. It had
been constructed out of 1/8” thick Aluminum 6063-T5 Angle, with structural rigidity and corrosion
resistance in mind [3] due to exposure to elements like water in the flat roofing environment. A Finite
Element Analysis had been performed on the frame, in various loading situations, to insure the material
selection and dimensions would satisfy the stakeholder need of being durable. The first simulation mimics
a 250 lbf person stepping in the center of one of the 22” long aluminum bars. By applying the load in the
center it mitigates the contribution the legs have at dispersing the load and is a better test for finding the
stresses at the welded joints. After running the simulation, the maximum Von Mises (28 ksi) and shear
(16 ksi) stresses occurred between the outer leg connection and the square frame. These results are shown
in Figures 2 and 3.
Figure 2: Von Mises Stresses with Footstep Load Figure 3: Shear Stresses with Footstep Load
Considering the fact that this device needs to be able to be transported, the next two tests were
performed in order to see how someone picking up the device will propagate stress. Constraining one of
the 22” long aluminum bars and applying gravity, the device experienced its greatest stresses on the
inside joint connections between the length and width pieces of the frame. For this scenario the maximum
Von Mises stress was 5.4 ksi and the maximum shear stress was 3.1 ksi. When only constraining one leg
and applying gravity, these stresses decreased to 1.1 ksi and 620 psi. The results can be seen below.

7
Figure 4: Von Mises Stresses Holding the Frame Figure 5: Shear Stresses Holding the Frame
Figure 6: Von Mises Stresses Holding One Leg Figure 7: Shear Stresses Holding One Leg
The last simulation mimics a human being pushing near the bottom of one of the legs with 30 lbf
of force. The stresses exhibited in figures 8 and 9 are among the weakest and are 11.6 psi and 6.5 psi.
These maximums occur along the edge where the leg and the square frame meets.
Figure 8: Von Mises Stresses Pushing with 30lbs Figure 9: Shear Stresses Pushing with 30lbs
Comparing the Von Mises and shear stresses to the yield and shear strength properties of
aluminum 6063, which are specified in Table 1, all stresses fall below these critical values except the first
test. The design team felt like this situation was the most uncommon and if these stresses needed to be
addressed that additional braces or bolts could be added to the design to alleviate them. Due to the
importance of being weather resistant, as well as having square 90 degree bends, the design team still
chose aluminum 6063. Lastly, a height clearance of 6” was implemented in the design of the frame to
accommodate for the height of the linear actuator and heating coil housing, while retaining the ability to
adjust the height of the heating coil beneath the prototype.
Table 1: Material Properties [4]
Ultimate Tensile Strength
(psi)
Yield Strength
(psi)
Shear Strength
(psi)
27,000 21,000 17,000
Aluminum 6063-T5

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3.5. C Drivetrain
The vehicle drivetrain was developed based on the proposed design for performance and
functionality. In order to satisfy design constraints, the drivetrain needed to be able to support and move
the maximum projected gross vehicle weight (GVW) of 50 lbs. This weight was based on the allowances
of the roof insulation surface and ability to transport the device to the rooftop. A size wheel diameter of
6” was selected to allow ample ground clearance for the mounted sensors and induction device, as well as
to propel the vehicle over small debris. The front wheels have a maximum load rating of 35lb each,
sufficient for the projected GVW. The front axle, a ½” aluminum shaft, was supported by two pillow
block bearings, which were selected after calculating the manufacture load and velocity specifications
below in Equations 1 and 2 [5].
𝑳𝒐𝒂𝒅 = 𝑷 =
𝑩𝒆𝒂𝒓𝒊𝒏𝒈 𝑳𝒐𝒂𝒅
(𝑫 𝒔𝒉𝒂𝒇𝒕∗𝑩𝒆𝒂𝒓𝒊𝒏𝒈 𝑳𝒆𝒏𝒈𝒕𝒉)
=
𝟒𝟖𝒍𝒃𝒔
(𝟎.𝟓"∗𝟎.𝟔𝟐𝟓")
= 𝟏𝟓𝟑. 𝟔𝒑𝒔𝒊 [Eq. 1]
𝑽𝒆𝒍𝒐𝒄𝒊𝒕𝒚 = 𝑽 = 𝑽 𝒔𝒉𝒂𝒇𝒕 ∗ 𝟎. 𝟐𝟔𝟐 ∗ 𝑫 𝒔𝒉𝒂𝒇𝒕 = 𝟗𝟓𝒓𝒑𝒎 ∗ 𝟎. 𝟐𝟔𝟐 ∗ 𝟎. 𝟓" = 𝟏𝟐. 𝟒𝟓𝒇𝒕/𝒎𝒊𝑛 [Eq. 2]
The selected pillow block bearings were rated at values of P=2000psi and V=1200 ft/min, which
confirm their feasibility for our maximum load and velocity conditions [5]. Below, Figures 10 through 12
are images of the wheels, motor assemblies, and pillow block bearings.
Figure 10: Front Wheel [6] Figure 11: Rear Motor Assembly [7] Figure 12: Pillow Block Bearing [8]
The rear wheels were designed to have two DC motors, one on each side, to propel the vehicle.
The projected maximum GVW was used once again, as well as the maximum desired speed and wheel
diameter to determine the required motor specifications. Equations 3 through 5 were used to calculate the
forces due to maximum roof gradient angle, rolling resistance due to surface friction, and acceleration [9].
The maximum roof gradient and surface friction, the highest approximated coefficient occurring between
the membrane and tire, were utilized for the most severe roof conditions that the device may encounter
[10].
𝑮𝒓𝒂𝒅𝒆 𝑹𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆 = 𝑮𝑹 = 𝑾 𝑮𝒓𝒐𝒔𝒔 ∗ 𝐬𝐢𝐧(𝑮𝒓𝒂𝒅𝒆 𝑨𝒏𝒈𝒍𝒆) = 𝟓𝟎𝒍𝒃𝒔 ∗ 𝐬𝐢 𝐧(𝟏𝟒°) = 𝟏𝟐. 𝟎𝟗 𝒍𝒃𝒔 [Eq. 3]
𝑹𝒐𝒍𝒍𝒊𝒏𝒈 𝑹𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆 = 𝑹𝑹 = 𝑾 𝑮𝒓𝒐𝒔𝒔 ∗ 𝐂 𝑭𝒓𝒊𝒄𝒕𝒊𝒐𝒏 = 𝟓𝟎𝒍𝒃𝒔 ∗ 𝟎. 𝟎𝟒 = 𝟐. 𝟎𝟎 𝒍𝒃𝒔 [Eq. 4]
𝑻𝒐𝒕𝒂𝒍 𝑻𝒓𝒂𝒄𝒕𝒊𝒗𝒆 𝑬𝒇𝒇𝒐𝒓𝒕 = 𝑻𝑻𝑬 = 𝑮𝑹 + 𝑹𝑹 = 𝟏𝟒. 𝟎𝟗 𝒍𝒃𝒔 [Eq. 5]
Once the total force needed to propel the vehicle, or TTE, was determined, the required torque
was calculated using Equation 6 and additional variables of wheel radius and a general resistance factor
from the gear drive system [9].
𝑻𝒐𝒓𝒒𝒖𝒆 𝑹𝒆𝒒𝒖𝒊𝒓𝒆𝒅 = 𝑻𝑻𝑬 ∗ 𝑹 𝑹𝒂𝒅𝒊𝒖𝒔 ∗ 𝑹𝑭 𝑹𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝟏𝟒. 𝟎𝟗𝒍𝒃𝒔 ∗ 𝟑" ∗ 𝟏. 𝟏𝟐𝟓 = 𝟒𝟓. 𝟓𝟓𝒍𝒃 ∗ 𝒊𝒏 [Eq. 6]
The selected motors came equipped with mounting brackets, wheels, tires, and encoders. The
maximum payload rating for both motors is 60lbs, and the maximum torque output is 85 in-lbs each,

9
therefore a total torque of 170 in-lbs which is within our minimum requirements of 45.55in-lbs. The kit
included encoders to track the rotation of each wheel with 144 positions allowing linear accuracy within
0.14”. The motors also operate up to 95 rpm using a 12V and 8A power source, however 31.8 RPM will
be sufficient for our maximum target vehicle speed of 25 ft/min, as per Equation 7 [7].
𝑹𝑷𝑴 𝑻𝒂𝒓𝒈𝒆𝒕 = 𝑽 𝑺𝒉𝒂𝒇𝒕 =
𝑽 𝑻𝒂𝒓𝒈𝒆𝒕
𝟎.𝟐𝟔𝟐∗𝑫 𝒔𝒉𝒂𝒇𝒕
=
𝟐𝟓 𝒇𝒕/𝒎𝒊𝒏
𝟎.𝟐𝟔𝟐∗𝟑"
= 𝟑𝟏. 𝟖 𝑹𝑷𝑴 [Eq. 7]
3.5. D Sensors
A very important part of the team’s design is the front mounted sensor array used for detecting
the metal plates beneath the membrane. Multiple sensors were considered and researched before the team
decided to pursue an inductive proximity sensor. These sensors use an oscillator driven coil to create an
electromagnetic field and when a metallic object comes in close contact to the face of the sensor, the
electromagnetic field decreases and the switch closes [11]. These sensors are relatively inexpensive, yet
are used in a wide variety of applications and are very accurate and reliable. The team chose a digital
sensor manufactured by Automation Direct, Model No. AT1-AN-3A. This model is shielded meaning the
sensor can only detect metal directly in front of the device [11]. It can operate from a distance of up to
15mm away from the metal object, it has a diameter of 30mm, and it has an NPN-normally open
configuration [11]. NPN configuration simply means that when no metal has been detected the sensor will
output slightly less than the voltage value that is being input, and when metal has been detected the output
will be connected to ground and read zero volts. This configuration was chosen due to the fact that no
stray voltage would cause a faulty or inaccurate reading since the “metal detected” state is zero volts.
Figure 13 displays the physical sensor and Figure 14 displays the NPN configuration in more detail.
Figure 13: Proximity Sensor AT1-AN-3A [11] Figure 14: NPN Output Configuration [11]
3.5. E Sensor Array
The function of the sensor array is to detect the location of the metal fastening plates that lie
under the roofing membrane without causing damage to the membrane itself. The array was designed to
prevent the metal fastening plates from going undetected when passing between the physical outer limits
of the array. This is done by spacing the individual sensors, as seen in Appendix B Figure 36, at
calculated intervals to allow for the fastening hex nuts on the sensors to be tightened without interference,
to have the minimal number of sensors required for accurate readings, and allow for the position of the
plates to be determined based on the layout of the sensors in relation to one another. The sensor diameter
is 30mm and the hex nut minor diameter is 36mm. The hex nut major diameter was determined from the
minor diameter of the hex nut and the geometric properties of a standard hexagon.
𝑫𝒊𝒂𝒎𝒆𝒕𝒆𝒓 𝒎𝒂𝒋𝒐𝒓 = 𝑫𝒊𝒂𝒎𝒆𝒕𝒆𝒓 𝒎𝒂𝒋𝒐𝒓 ∗ 𝐭𝐚𝐧(𝟑𝟎°) +
𝑯𝒆𝒙 𝑵𝒖𝒕 𝑴𝒊𝒏𝒐𝒓 𝑫𝒊𝒂𝒎𝒆𝒕𝒆𝒓
𝟐∗𝐜𝐨𝐬(𝟑𝟎°)
= 𝟏. 𝟔𝟑𝟔𝟓𝟖 𝐢𝐧 [EQ. 8]
Based on these criteria, the frame of the array was to be the same width as the frame of the
overall device and the sensors would occupy the same width as the maximum range of the linear actuator,
10 inches. The outer sensors need to have their centers coincidental to the outer most range of the linear
actuator. This meant that the number of sensors needed is dictated by the following equation with the
sensors being placed as close to one another as possible for better sensing resolution.

10
𝑵𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒔𝒆𝒏𝒔𝒐𝒓𝒔 =
𝑨𝒄𝒕𝒖𝒂𝒕𝒐𝒓 𝑹𝒂𝒏𝒈𝒆
𝑯𝒆𝒙 𝑵𝒖𝒕 𝑴𝒂𝒋𝒐𝒓 𝑫𝒊𝒂𝒎𝒆𝒕𝒆𝒓
+ 𝟏 = 𝟕. 𝟏𝟏 ≈ 𝟕 [EQ. 9]
The “+1” term is to allow for the outer sensors to be centered at the range of the actuator. This
shows that seven is the ideal number of sensors. Between each sensor is half an inch of region that cannot
sense metallic objects but since the plates being located are three inches in diameter this does not affect
the ability of the array.
3.5. F Induction Coil
The hot plate would serve as a critical component to the function of the prototype, delivering
electrically induced magnetic fields to the fastener plate which in turn generate heat due to the materials
resistance to the flow of induced current. This then results in a permanent weld, or bond, between the
material and fastener plate. The design team had initially set out to design a job-specialized hot plate from
scratch, however it was quickly realized that it would have been a separate design challenge in itself and
would stray from the scope of the project. Instead, research had been conducted to select a hot plate that
would best realize the mission goal and thus reducing job time, weld error, and manpower. A portable
induction cooktop had been selected based on 2 characteristics, namely the controllability of the device
and its maximum power output at 1800W. Controllability can be further broken down into 3 key aspects,
utilized in the design of the prototype deliverable. These include the ability to enable the device,
switching it on or off, regulating the power level, 0W to 1800W, and being able to strike the device into
oscillation, otherwise initiating the inductive heating process. All 3 of these aspects are handled by the
cooktops onboard computer, with the logic circuitry having already been developed for simple I/O
(Input/Output) and power regulation by Pulse Width Modulation (PWM), therefore making it simple to
commandeer. The connections to the cooktop controller had then been bypassed and distributed to an
Arduino microcontroller board for implementation of a custom control algorithm. The maximum power
output of 1800W had been dependent on the hotplate model itself, due to salvaging components which
would be included in the design of the overall prototype. This maximum of the cooktop is ideal because it
translates to a peak work-piece temperature of approximately 232°C [12] just slightly above the ideal
welding temperature of the fastener plate and membrane. Note that ideal welding temperature had been
pre-determined, through research performed by the project sponsor, to be 225°C [13] making it just
within the capabilities of the cooktop.
In order to calculate a specific heating time, an approximate value can be obtained using
Equation 10 for specific heat capacity below combined with knowledge of the work coils power output.
Mass of the fastener plate is approximated to be ½ lb.
𝒅𝑸 = 𝒎𝑪 𝒑∆𝑻 = 𝒎𝑪 𝒑(𝑻 𝟐 − 𝑻 𝟏) [Eq. 10]
Table 2: Variables Definitions
Sample Calculations 𝒅𝑸 = (. 𝟏𝟏𝟑)(𝟎. 𝟒𝟗)(𝟐𝟐𝟓 − 𝟐𝟎) = 𝟏𝟏. 𝟑𝟓𝑲𝑱
𝑷 =
𝒅𝑸
𝒕
→ 𝒕 =
𝒅𝑸
𝑷
=
𝟏𝟏. 𝟑𝟓
𝟏𝟖𝟎𝟎
= 𝟔. 𝟑𝟎𝟓𝒔
Quantity Description Value
dQ(KJ) Required Energy to Achieve Temperature Differential 22.782
mass (kg) Fastener Plate Mass 0.113
Cp (KJ/kg) Carbon Steel Specific Heating, Constant Pressure 0.49
T1 (⁰C) Ambient, Initial Temperature 20
T2 (⁰C) Final Temperature 225
Power (W) Power Output 1800

11
Equation 10 can also be used as necessary for later implementation in the prototype design for
accommodating various surface temperatures. This initial temperature parameter could then be modified
in the controller program to compensate for warmer or cooler days. Further testing had been conducted to
characterize the heating pattern of the metal plates as well as record equilibrium temperatures with which
various power levels had been capable of achieving. This information was used to develop an ideal
heating cycle which would best reach the steady state temperature of 225°C, and then maintain steady
state, discussed further in Section 3.3.
The physical construction of the prototypes heating mechanism began with extraction of the
heating coil and printed circuit board containing the electrical circuit for necessary functionality. The
printed circuit board would essentially be separated from its compact design in the cooktop to a
completely isolated area on the top of the prototype for protection from the elements. In contrast to the
electrical components, the coil needed its own specialized housing, shown below in Figure 15. The
housing material is made of an electrically insulating Noryl PPO selected for its material properties. It is
rated for temperatures up to 220°F (104°C) and temperatures as low as -40°F (-40°C), making it suitable
to withstand both the coldest and hottest days, as well as indirect heating from the fastener plates. It also
provides moisture resistance and high impact tolerance [14], making it ideal for outdoor applications.
Lastly, the material is electrically insulating keeping the high current, being passed through the heating
coil, contained and safe for operation to on-site personnel. An order of 3/8” thick, 12”x12” material had
been ordered and machined into the housing configuration below. The housing had also been machined
with two holes for the electrical leads to pass through which will later be completely sealed with silicon or
rubber grommets. Finally, the coil was mounted to the linear actuator on the interior of the prototype so
that it may translate laterally to the location of fastener plates beneath the membrane.
Figure 15: Coil Housing
3.5. G Induction Coil Sensor
The overall accuracy of the positioning of the induction coil based on the front sensor array alone
proved to be much lower than the team had initially calculated, so an important addition was designed to
create higher accuracy. This new addition consisted of another Automation Direct Model No. AT1-AN-
3A, NPN inductive proximity sensor placed at the center of the induction coil. The induction coil being
utilized for the prototype had an existing hole in the center of it with a diameter of 35mm, 5 mm larger
than the diameter of the sensor. The sensor was placed at the center of the coil with offset spacing of
approximately 5mm behind the induction coil. This offset spacing was incorporated so that the induction
coil’s magnetic field would not interfere with the operation of the sensor. This single center sensor would
then be utilized to map the outside points of the detected metal plate, and use the points to calculate the
center of the plate and relay that information to the linear actuator and motors of the prototype to position
itself accordingly. Due to the addition of this sensor, the devices detection accuracy was calculated to be
74%. This measurement takes into account the 0.2in tolerance of the ultrasonic sensor, and the 0.14in
tolerance of the motor encoders, to find the difference of area overlay of the heating coil and metal plate.
More information on this overall process is discussed in the Logic Design section of the Detailed Design
Section.

12
3.5. H Linear Actuator & Ultrasonic Sensor
Since it was decided that the device was to follow a linear path for simplicity, it would need a
way to position the induction coil assembly in order to match the position of the plates as they are
detected by the sensor array. This required some sort of linear translating device. A few early ideas were
to use a motorized pulley design, but the predicted issues were cable/belt slippage or motor coasting that
would affect the accuracy of the position of the coil assembly. The strength of a system like this was also
under question. The method decided on by the project group was to use a system that utilized a motorized
power screw. This would be a robust and accurate solution to allow for linear translation of the coil
assembly. The linear actuator being used was chosen since it was the correct dimension and used a
common voltage and amperage. The chosen linear actuator was manufactured by Firgelli Automation and
has a linear span of 15”. This actuator, however, does not have any kind of encoder that allows for the
position of the actuator to be communicated or recorded to the microprocessor. The addition of an
ultrasonic sensor was chosen by the team to monitor, record, and adjust the physical position of the linear
actuator. The ultrasonic sensor is produced by Parallax and is called the PING Ultrasonic Distance
Sensor. A bracket was constructed out of left over aluminum from the frame to work in connection with
the ultrasonic to record and modify the distance of the linear actuator. Figure 16 displays the ultrasonic
sensor and Table 4 displays the relevant specifications on the sensor. The weight of the coil assembly is
also calculated to be significantly less than the limitations of the actuator shown in Table 3.
Table 3: Linear Actuator Parameters [16]
Table 4: Ultrasonic Sensor Specifications [17]
Figure 16: Picture of Ultrasonic Sensor [17]
3.5. I Pressure Roller
The sponsor’s current product required heat-dissipating magnets to be placed on top of the
membrane after each plate was welded. In order to compliment this feature on the prototype, a rear
mounted roller was designed and constructed. The roller’s purpose was to apply a steady pressure to the
membrane as the prototype rolled past a welded plate. This would eliminate any air gap between the plate
and membrane ensuring a close bond to the plate. Brackets were designed on the rear legs of the frame,
those of which utilized two rotating arms, positioned at approximately 45° from the horizontal. In order to
calculate the spring constant needed to apply the desired downward pressure on the roller, the bracket and
arm dimensions, roller diameter, and weight of the prototype were used with Figure 17 and Equation 11
below. The spring utilized on the prototype had a spring rate of 9.3 lbs/in, therefore it would be able to
supply approximately 5lbs of pressure downward to the membrane.
Parameter Value
Linear Rate 2 in/s
Static Force 70 lbf
Dynamic Force 30 lbf
Specification Value
Operating Voltage 5 VDC
Range 2cm to 3m
Communication Positive TTL Pulse

13
𝒌 =
𝑭
𝒙
=
𝟓𝒍𝒃𝒔
𝟎.𝟓"
~𝟏𝟎𝒍𝒃𝒔/𝒊𝒏 [Eq. 11]
Figure 17: Pressure Roller Drawing
3.5. J Control System
Research was performed to determine the controller needed to drive the control system for the
prototype. Some of the topics considered when conducting the controller research included operating
voltage, number of input/output pins, flash memory, SRAM and clock speed. The Arduino platform was
chosen due to the fact that Arduino’s products are rather inexpensive, and it is an open-source electronic
prototyping platform. There is a vast amount of example projects and sketches available for use along
with a great amount of support for both design and troubleshooting related issues. The Arduino Mega
2560 was chosen as the physical controller. The Mega 2560 has a standard operating voltage of 5 volts,
54 digital input/output pins, 16 analog input pins, and a clock speed of 16 MHz which are all values that
theoretically match the needs of the physical prototype [15]. Table 5 summarizes the important
information pertaining to the overall performance of the Mega 2560. The team estimated approximately
20 input/output pins would be needed for most of the prototype’s components including the sensors,
linear actuator, and induction coil.
The motors needed to drive the prototype were separately considered from the other components
as an h-bridge as well as other electrical components would be needed to gain full control of the motors.
An Arduino compatible motor shield was chosen to be used for the prototype as the shield contains all of
the necessary hardware to fully control the speed, direction and faults of the motors. The motors chosen
for the project operate at a higher voltage and current level, specifically 12 volts and up to 8+ amps for
full operation. Thus, the Pololu Dual VNH5019 Motor Driver Shield was selected as it has the capability
to drive motors rated for 5.5 to 24 volts, and up to 12 amps [18]. The shield allows for easy control as it
also comes with an Arduino library specifically for controlling speed, brakes, and direction. The selected
motor shield utilizes 8 digital pins and 2 analog pins, meaning 46 digital pins and 14 analog pins remain
for other selected components. A relay board was utilized for proper functionality of the linear actuator
and induction hotplate. This allowed the induction hotplate to be powered on or off, and the linear
actuator to be adjusted in either direction. All of the various components were connected and soldered to
create a reliable control system. An electrical project bow was purchased to house all of the various
wiring and connections, and three fans were installed to ensure that all of the components maintained an
appropriate temperature.
Table 5: Summary of the Arduino Mega 2560 [15]
Controller Attribute Value
Operating Voltage 5 V
Digital I/O Pins 54 (15 for PWM)
Analog Input Pins 16
DC Current per I/O pin 40 mA
Flash Memory 256 KB
SRAM 8 KB
Clock Speed 16 MHz

14
3.5. K Detailed Prototype Pictures
Figure 18: Front Left Side View of Prototype Figure 19: Rear Right Side View of Prototype
Figure 20: Right Side View of Prototype Figure 21: Prototype Electrical Housing View
3.6 Prototype Verification and Testing
The design team had evaluated the prototypes performance by recreating a section of roof in a
controlled environment at the project sponsor’s facility. Three rectangular sheets of insulation had been
placed adjacent to one-another lengthwise, with an additional section placed atop each. The design team
arbitrarily placed plates, with fasteners, across the insulation boards. Finally, a layer of weatherproof
membrane had been laid overtop the metal plates to complete the test section assembly. It should be noted
that the plates had been placed equidistant from one another with 2 ft. of spacing. They had also been
placed irregularly in the lateral direction to better test the linear actuator’s functionality. A typical pattern
used in this process would be more accurate. Figure 22 below illustrates the test setup with magnets in a
readied position for placement on top of heated plates.
Figure 22: Test Section Setup

15
The core objectives of the test had been to record the total job duration from an un-readied
position to completion of the final weld, record the time from weld to weld, and then test the weld
strength using a tensile testing machine. Results from the design team’s device were then compared to the
performance of the sponsor’s current device. Figure 23 illustrates the prototype traversing the test section
with magnets placed atop the already heated plates. Figure 24 illustrates the tensile test setup from which
all weld strength data had been derived.
Figure 23: Prototype Executing Test Figure 24: Pull Test Setup
A series of 6 weld duration tests had been executed prior to the main testing mentioned
previously, which would serve to optimize the devices welding potential. The design team now had
access to the tensile testing machine, and could therefore determine the strength results of various heating
durations. It had been known from thermal tests conducted in the winter term that the plate had been able
to reach the optimal temperature of 225 ℃ [13] in 6 seconds however it was unknown if this time was
ideal to tell if the adhesive coating across the plates surface had been thoroughly bonded with membrane.
Therefore, bond strength had been tested with a heat time of 6s, 7s, 8s, 9s, 10s and 12s respectively.
Results had shown that 6 seconds had hardly melted the adhesive coating, the plate retaining its pink color
shown in Figure 25, while 12 seconds had thoroughly burned the coating away, illustrated in Figure 27.
The burning is detrimental to the strength of a weld just as much as not welding the plate thoroughly
enough. Of the remaining test results, the 10s heating time had proven to show the most promise. Figure
26 shows the weld quality of a 10s heating duration while Table W shows the tensile strength achieved by
each heating time. Notice the difference between the 6s duration and 10s duration. The 6s duration
illustrates a weld failure, while the 10s duration shows a material failure.
Table 6: Various Heating Durations Quantitative and Qualitative Results
Heat Time (s) Plate Appearance Membrane Appearance Weld Strength (lbf)
6 NA NA 332.59
7 NA NA 283.49
8 NA NA 520.47
9 NA Rubber slightly melted around welded edges 468.05
10 Slight discoloraion around welded edges Rubber slightly melted around welded edges 582.25
12 Resin burnt off around welded edges Rubber melted around welded edges 619.28

16
Figure 25: 6s Weld Time Figure 26: 10s Weld Time Figure 27: 12s Weld Time
The second set (the main set) of tests had then been conducted. Recall, the cumulative test time
had been recorded along with each subsequent weld throughout the duration. The ten plates were then
extracted from the test section and tested for strength. Of the 10 total plates, 9 had actually welded with
an anomaly occurring during the welding of the 6th
plate. This was attributed to sensor failure within the
coil housing. The close proximity of the device’s heating coil and inductance sensor had proven to cause
occasional misreading. The failure to weld plate 6 had not been averaged with the other 9 confirmed
welds in order to preserve an accurate average. The exact same test had then been performed using the
sponsor’s current device in order to contrast the prototype. Figure 28 graphically illustrates a comparison
of the detection time for each device. It shows that the prototype is significantly more consistent than the
sponsor’s current tool, whereas minimal fluctuation in this value is attributed to the translating of linear
actuator or human inaccuracy in timing. Figure 29 shows the weld strength acquired by each device. It
should be noted that the sponsor’s device encountered issues with bunching the membrane material and
therefore weld quality suffered, producing poor results. Tables 11 and 12 can be found in the appendix
form which the graphical results had been derived. Table 7 shows the overall evaluation of both devices.
Figure 28: Detection Time Results Figure 29: Weld Strength Results
Table 7: Overall Comparison
Metric Prototype IsoWeld
Pre-Alignment Time (s) 23 0
Detection Time (s) 12.856 12.514
Weld Time (s) 10 6
Total Job Time (s) 255.94 185.14
Total Personel Time (s) 23 185.14
Failure Rate (%) 10% 0%
Weld Strength (lbf) 655.52 583

17
At first glance, the test results appear to favor the ISOWeld’s performance over the developed
prototype. An analysis of the bigger picture is required to understand how the product improves the
welding process and achieves the desired objectives. The total duration of the job for the prototype is
approximately a whole minute longer than the current device however the user only has to physically
handle the prototype for an average of 23 seconds during a pre-alignment phase. Thus the remaining time
can be utilized for other tasks. The average detection time for each device is roughly the same but the
above figures illustrate that the prototype is much more consistent, and therefore able to deliver more
reliable results. The weld time is 4 seconds longer per plate which is attributed to the type of coil used in
the design but recall that this heating coil is a modified off-the-shelf device. A custom coil could reduce
weld time and be adapted to the device, thus decreasing total job time. The prototype had failed to weld
10% (1 physical plate) of a total of 10 plates. Though this value is large, the sample size had been small
and therefore a conclusion on reliability is not clear. There are known issues with the inductance sensor
within the coil housing and the relay board, and may be attributed to this failure rate. Finally, the
prototype had delivered results above 583lbf, the average weld strength for the current device, with
tensile testing. In summary, the device had consistently supplied above average results and reduced the
total duration of operator interaction to 23 seconds.
IV. Context and Impact
4.1 Economic Impact
Economic impacts of this project are most relevant to commercial roofing contractors, product
manufacturers, and commercial flat roof owners. Thermoplastic membranes are a very established and
common method of roof design, however mechanically fastened membrane is a more specific and smaller
product group. The limited quantity of devices available to install these roofs make a very competitive
market therefore this device was important for the sponsor’s product line. The better functionality and
user ergonomics, greater capabilities, and reduced cost of this product will give the stakeholders an
advantage in the market. The prototype was constructed out of readily available, off-the-shelf parts,
available from a variety of online and in-store suppliers. The construction of the components was very
straight-forward, requiring only general mechanical skills to modify or repair any malfunctions. Overall,
the prototype required approximately half of the overall budget, providing a fully functional and
operational device, at one half of the money potentially invested in the project.
In order to improve the manufacturability and overall cost of the full-scale production of the
prototype, some amendments could be implemented. Components, such as the frame and additional
bracketry, could be produced as one entire weldment, welded by an automated facility for more precision
tolerances. The various electronics and controllers could be pre-assembled and built into a circuit board,
mass produced for a reduced cost from hardwiring as well to save space. Finally, the induction coil
though very functional, could be broken down into simpler components, rather than purchasing an entire
unit and dismantling for the needed components. Overall, the prototype provides an excellent proof of
concept, as well as versatile platform for future modifications or full-scale production.
4.2 Environmental Impact
The materials utilized for the fabrication of the prototype’s frame and main body consist of
extruded aluminum and stainless steel fasteners. The pre-formed aluminum structural members of the
frame are ideal for the design, and also can be easily recycled for other repurposed material
manufacturing. The ABS plastic electrical cabinet, as well as shelving and bracketry also are of recyclable
materials and produced under lean manufacturing processes. One of the specifications for the conceptual
prototype was to have a high structural integrity, while remaining easily repairable and adaptable. This
creates a device that will last for many years and ultimately allow for reuse and adaptability in various
applications. The prototype does not directly release a significant amount of environmentally harmful
particles into the atmosphere, as it will only be slightly heating metal plates to adhere to the roofing
membrane, and not completely igniting the entrapped chemicals. The design is intended to be as
environmentally friendly as possible while still performing its purpose sufficiently.

18
4.3 Social Impact
Improving a product often results in development of certain tradeoffs and possible risks.
Improving efficiency and automation, for example, can lead to lower skilled labor employment while also
increasing higher technical positions. The device was designed to allow the worker to be more valuable to
a company by producing more work output in a shorter timeframe. The operator’s quality of life was also
improved, preventing the normal wear and tear which occurs from physical labor in the construction
environment. Due to the reduction of health risks, the individuals available to perform these types of jobs
will likely increase, and hold higher appeal. Lastly, in order to make this device accessible to a variety of
company sizes, the design has to be cost effective and simple to operate. This allows for intuitive
operation of the device regardless of education or experience level.
4.4 Ethical Impact
The prototype was developed with regard to safety for the operators and general public occupying
the areas around the work site. The operation of the device has no inherent hazards to the user, due to the
very brief interaction between the device and the operator. Though as with all electrical equipment the
risk of shock exists if electrical leads are exposed, all of the electronics and wiring has been concealed
and insulated. In an extreme case that a user may have a pacemaker, possible interference could occur due
to the properties of the induction coil, therefore precautions should be taken to avoid any close
interaction. All of the moving components and oscillating arms have been mounted under the device,
away from direct operator contact, and any edges or cut material have been rounded and chamfered to
avoid sharp edges.
V. Project Management
5.1 Team Organization
All of the documents created and utilized throughout the project were accessed and stored in the
team’s Google Drive. The five members of the team each had specific major roles in both the design and
creation of the prototype but also performed general tasks such as overall design, construction, and
troubleshooting equally. Every member had a part in the overall design of the proof of concept prototype.
Listed below is a brief description of the specific major role that each separate team member had in the
project:
Tyler Darrah (Mechanical Engineering)
 Responsible for integrating induction technology into the prototype. This includes market
research, understanding fundamental induction principles, preliminary calculations, testing,
and analysis.
Justin Dempsey (Electrical Engineering)
 Responsible for developing the main control system of the prototype. This includes market
research, understanding fundamental principles, programming, and logic design.
Elliot Farquhar (Mechanical Engineering)
 Responsible for CAD drafting and modeling as well as fabrication. This includes the
utilization of manufacturing tools and design troubleshooting.
Joe O’Brien (Mechanical Engineering)
 Responsible for motor integration and part sourcing. This includes market research,
preliminary calculations, and analysis.
Robert Stricek (Mechanical Engineering)
 Responsible for performing finite element analyses and sensor integration. This includes
market research as well as a fundamental understanding of finite software and analysis.
5.2 Schedule and Milestones
An outline schedule, Appendix A, Table 8, was constructed to remain punctual on all
submissions, periodic progress reports, and overall project progress. The team immediately began

19
producing a list of needs and specifications as initial project requirements were presented by the sponsor
during the Fall Term. The list consistently developed as additional stakeholders and specifications were
found through component research, contractor job site visits, and product impact studies. An initial phase
was then started, focusing on understanding the current processes and available technology for roofing
membrane attachment, as well as additional technologies that had not yet been tried. Periodic team
meetings were conducted multiple times per week to present findings and hold discussions. Bi-weekly
meetings were also conducted with a representative from the sponsor to assist with idea generation and to
provide available technical information on the current product. The Fall Term was designated as strictly a
“proposal stage” to perform research, gain a better understating and begin narrowing down various
prototype ideas.
The Winter Term was spent primarily as a construction and testing phase. After deciding on the
best design to sufficiently meet the various needs and specifications, CAD models were generated,
analysis was performed and construction was started. The general frame was designed and FEA analysis
was conducted to determine the overall strength of the designed frame. Individual components were
selected based off of functionality and calculations, and extensive testing was performed to better
understand the exact operation of the selected components. The induction hotplate was thoroughly tested
to gain full operation of the device outside the actual control system of the hotplate, and thermal imaging
was performed to determine if the selected hotplate would perform sufficient welds. Overall, the Winter
Term was spent mostly testing and constructing the physical prototype and the various components.
The Spring Term was spent almost entirely developing and finalizing the control system for the
teams design as well as finalizing the construction and addition of a few components. The first three
weeks of the term were spent developing the Arduino program needed to perform all of the operations for
the design. Upon full development of the code, the numerous electrical connections were made permanent
by soldering numerous connections. The majority of wires and connections were placed into an electrical
project box to create more reliable connections that could be easily observed and modified if needed.
Final testing was then performed to ensure that all of the specified logic was properly incorporated. A
final test was conducted at the Sponsor’s Facility to fully observe the operation of the teams designed
prototype. A side by side comparison was performed between the team’s prototype and the sponsors
existing product. This data collected from the visit to the sponsor facility would determine the overall
success of the project and if the specified deliverables were met.
5.3 Project Budget
The budget for the project was provided by the team’s sponsor company in the amount of $5000.
The budget was planned to cover the cost of any materials, tax and shipping, and fabrication labor by any
outside source. The total budget that was spent to complete the project was $2603.23, which was just over
half of the allotted amount. The bill of materials for the project is shown in Table 9, Appendix A. The
document lists every component utilized for this project, including part numbers, manufacturer or seller,
and cost. Overall, the team successfully met the specified deliverable of creating a cost-efficient prototype
spending nearly one half of the provided budget.
VI. Discussion
The design process had started by working with the project sponsor and job personnel to establish
their respective stakeholder needs and specifications. Throughout the duration of the design process, these
needs and specifications had to be re-evaluated to better focus the overall scope of the project. The design
team had been ambitious and considered delivering as many of the stakeholders requests as possible. This
proved to be unrealistic and therefore the design team and sponsor agreed to pursue critical functionality
and priority 1 needs first. It is because the team had been so ambitious that considerable research had
been conducted in induction welding technology and coil design, which later had been discarded because
of the focusing of project scope. This had consumed valuable time that would have been allocated to
developing product concepts. Physical prototyping of the selected concept had been delayed as well due

20
to a legal agreement between the University and project sponsor, which had not been established until the
final week of the term.
The nature of the project did not require extensive theoretical calculations to be performed, rather
it required thought as to how a device could perform necessary operations to find metal plates, position it
and weld them. Significant calculations involved complex geometries considering plate location scenarios
and prototype size as well as planning the positioning algorithm used in the controller. Minor calculations
had also been conducted to approximate the heating potential of the device’s welding coil. Therefore, in
summary, this design project had provided a unique solution to a unique problem using existing
technologies.
The design team had initiated the fabrication process in the winter 2015 term, embodying the
concept developed in the previous academic quarter. This had been an adaptive process, requiring the
group to think every step of the way. The aluminum frame was not designed with tight tolerances and it
had not been considered that thin aluminum stock is very difficult to effectively weld. Therefore, the
design team had to continuously adapt measurements in order to keep the device’s axles level. The sensor
array stock had to be completely replaced because of drilling with an un-lubricated bit using one of the
shop’s drill presses had produced too large a hole. There is considerable thought that had gone into
hardware selection, as to how pieces of the device would fit together, as well as how to wire the
connections to various electrical components. Programming had been another significant aspect of the
projects development. Without it, the device would be completely non-functional. Both this and the
electrical layout had been some of the more complex aspects of the design because it is difficult to
physically sense and troubleshoot issues. The system could become unresponsive because of a loose
connection or the controller program could use troubleshooting. A complex algorithm had to be
developed to position the device in the XY-plane which required in depth brainstorming by the group as a
whole. Even though there had been a lead programmer, the team had been involved with aiding in the
development of control logic. Each member of the senior design team had been equally involved in all
facets of the design process, with many mistakes and challenges faced along the way, which provided just
as much a learning experience as the research and designing phases.
The senior design team had worked with the project sponsor to develop a unique solution from
the ground up. The team had worked with stakeholders to establish their needs and base the design off of
such needs. Refocusing of the scope had been necessary along the way, stressing that the solution be a
proof of concept. It had delivered core functionality, however it also establishes a base point from which
several ideas and designs can be developed or adapted. Overall, the product had produced above average
weld strength results while having reduced the physical interaction time of the user by 83% at 1/8th
the
cost of the current device, thus deeming the design efforts a success.
VII. Summary and Conclusions
Determined from testing, the team accurately located and performed ideal welds on the plates
while requiring little to no hands on interference from a user and performed the tasks in a similar time to
the current tools in the field. The test in which multiple plates were in a row on a simulated roof displayed
the device’s ability to perform its programmed tasks in the way it was theoretically conceived. The welds
were then destructively tested and found to be greater or equal to that of the current tool.
The device created by the team is only a prototype and requires more iteration before it is market
ready. Some issues that were experienced were due to faulty sensors (induction proximity sensors,
ultrasonic sensor, and the motor encoders). Occasionally they were prone to failure or false readings that
the team was aware of through constant component testing. This did not prevent the concept from being
proven and tested, but can only be improved in the future through use of more reliable hardware.
Overall, the project was considered a success by the team as well as the sponsor. The team only
used about half of the allotted budget, created a device that meets the needs set forth, performs the
required tasks at or above satisfactory level, and this project proved to be a professional engineering
learning experience for the team members.

21
VIII. Future Work
This project focused on the design and physical construction of a base platform proof of concept
prototype. Every aspect from the frame itself to the complete working control system needed to be
researched, designed and created throughout the course of this nine month project. Since the focus was on
designing a base platform, there are numerous areas for future work for this project.
The first area of future work would be to custom design and engineer a working induction coil.
The team decided to reverse engineer and modify an existing induction hotplate to satisfy a need for the
prototype due to the extensive list of needs and specifications that were required to be met for the project.
Use of the sponsors current coil design would definitely be an improvement for the prototype, due to the
extensive development behind it.
Another area of future work would be to engineer a mechanism for the rear of the prototype to
eliminate the need for post –weld plates. Currently, after a weld is performed a magnet heat sink is place
directly on top of the weld to ensure a strong durable bond. Since the teams primary focus was on
automating the welding process itself, this mechanism was not able to be designed or constructed for the
existing prototype but would also be a major improvement and addition to the existing platform.
There are many other areas of future work such as adding a human machine interface directly to
the physical prototype to allow any user or operator to directly enter information pertaining to the welding
process to adjust certain settings. The entire platform could also be constructed in a more industrial
marketing fashion so that it can be mass produced and actually sold and utilized for this roofing
application.
Overall the team designed and constructed a highly successful base platform that performs semi-
autonomous welds very well. Due to the fact that the system was required to be researched, designed and
created from the ground up, the amount of additions and improvements were extremely limited simply
because of time constraints. A large amount of time and research was dedicated to researching various
applicable components to ensure that the design would be effective. Many hours were also spent
troubleshooting the device to create a successful working prototype and future additions would only
create an even more successful product.

22
IX. References
[1] “Mechanical Fastening Systems for Flat Roofs.” SFSintec.biz. SFS Intec, 6 Aug. 2013. Web. 23 Nov. 2014.
http://sfsintec.biz/en/web/industry_solutions/construction/flat_roof/flat_roofing.html
[2] Eppinger, Steven D., and Browning, Tyson R.. Engineering Systems : Design Structure Matrix Methods and
Applications. Cambridge, MA, USA: MIT Press, 2012. ProQuest ebrary. Web. 23 November 2014.
[3] Metalsdepot.com, 'MetalsDepot® - Buy Aluminum Angle 6063 Online', 2015. [Online]. Available:
http://www.metalsdepot.com/products/alum2.phtml?page=aangle&LimAcc=%20&aident. [Accessed: 25- Feb-
2015].
[4] Asm.matweb.com, 'ASM Material Data Sheet', 2015. [Online]. Available:
http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6063T5. [Accessed: 27- Feb- 2015].
[5] Mcmaster.com, 'McMaster-Carr', 2015. [Online]. Available: http://www.mcmaster.com/#about-sleeve-
bearings/=w2kjjm. [Accessed: 25- Feb- 2015].
[6] Lowes.com, 'Shop Arnold 6-in x 1-1/2-in Plastic Wheel at Lowes.com', 2015. [Online]. Available:
http://www.lowes.com/pd_543181-442-490-320-
0002_4294612675__?productId=50119663&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_
product_qty_sales_dollar%7C1&facetInfo. [Accessed: 25- Feb- 2015].
[7] Parallax.com, 'Motor Mount & Wheel Kit - Aluminum', 2015. [Online]. Available:
http://www.parallax.com/product/28962. [Accessed: 25- Feb- 2015].
[8] Mcmaster.com, 'McMaster-Carr', 2015. [Online]. Available: http://www.mcmaster.com/#standard-plummer-
block-mounted-bearings/=w56aod. [Accessed: 25- Feb- 2015].
[9] Whitedriveproducts.com, 'WHITE DRIVE PRODUCTS, INC.', 2015. [Online]. Available:
http://www.whitedriveproducts.com/. [Accessed: 25- Feb- 2015].
[10] Metalconstruction.org, 'Low Slope Roofs', 2015. [Online]. Available:
http://www.metalconstruction.org/index.php/applications/low-slope-roofs. [Accessed: 1- Mar- 2015].
[11] Automationdirect.com, 'AT1-AN-3A | 30mm Inductive Proximity Sensor (proximity switch): NPN, 15mm
range', 2015. [Online]. Available: http://www.automationdirect.com/adc/Shopping/Catalog/Sensors_-z-
_Encoders/Inductive_Proximity_Sensors_-z-
_Proximity_Switches/30mm_Round_Industrial_Automation/Extended_Sensing_Distance_(30mm)/AT1-AN-3A.
[Accessed: 25- Feb- 2015].
[12] Product Data Sheet, Max Burton Deluxe Induction Cooktop, 1st ed. Gardnerville, NV: Aervoe Industries Inc.,
2015, pp. 1-2.
[13] SFS intec Ltd, 'Investigation of the Inductive Heating Behavior of Plates for Roof Mounting', Christian
Lammel, Ismaning, Germany, 2011.
[14] Mcmaster.com, 'McMaster-Carr', 2015. [Online]. Available: http://www.mcmaster.com/#noryl/=w2fid1.
[Accessed: 25- Feb- 2015].
[15] Arduino.cc, 'Arduino - ArduinoBoardMega2560', 2015. [Online]. Available:
http://arduino.cc/en/Main/ArduinoBoardMega2560. [Accessed: 25- Feb- 2015].
[16] Firgelli Automation, ‘Mini Track Linear Actuator’, 2015. [Online]. Available:
https://www.firgelliauto.com/products/mini-track-actuator
[17] Parallax Inc., ‘PING))) Ultrasonic Distance Sensor’, 2015. [Online]. Available:
https://www.parallax.com/product/28015
[18] Pololu.com, ‘Pololu Dual VNH5019 Motor Driver Shield Users Guide’, 2015. [Online]. Available:
https://www.pololu.com/docs/pdf/0J49/dual_vnh5019_motor_driver_shield.pdf. [Accessed: 25- Feb- 2015].

23
X. Appendix A
Table 8: Project Schedule Gantt Chart

24
Table 9: Bill of Materials
Part # Vendor Part Description Qty. Unit Price Total Price Ordered
AT1-AN-3A Automation Direct Inductive Proximity Sensor 1 32.5 32.5 1/6/2015
191 AdaFruit Arduino Mega 2560 1 45.95 45.95 1/7/2015
62 AdaFruit Arduino USB Cable 1 3.95 3.95 1/7/2015
798 AdaFruit 12VDC 1A power adapter 1 8.95 8.95 1/7/2015
147 AdaFruit Wire Cutters 1 6.95 6.95 1/7/2015
368 AdaFruit Female DC Power Adapter 1 2 2 1/7/2015
369 AdaFruit Male DC Power Adapter 1 2 2 1/7/2015
290 AdaFruit Wire Spool Black 22AWG 1 2.5 2.5 1/7/2015
288 AdaFruit Wire Spool Red 22AWG 1 2.5 2.5 1/7/2015
289 AdaFruit Wire Spool Yellow 22AWG 1 2.5 2.5 1/7/2015
153 AdaFruit Breadboarding Wire Bundle 1 6 6 1/7/2015
239 AdaFruit Breadboard 1 5.95 5.95 1/7/2015
VNH5019 Pololu Pololu Arduino Motor Shield 1 49.95 49.95 1/7/2015
34102 Walmart
Hamilton Beach Induction Cooktop
(1800W) 1 70.03 70.03 1/8/2015
28962 Parallax
Aluminum Motor Mount and Wheel
Kit 1 299 299 1/14/2015
AT1-AN-3A Automation Direct Inductive Proximity Sensor 1 32.5 32.5 1/15/2015
B0037Z7HQK Amazon
Max Burton Induction Cooktop
(1800W) 1 106.98 106.98 1/16/2015
88805K94 McMaster-Carr
Aluminum Angle 6063, 2"x2", 1/8"
thick, 8ft 2 32.6 65.2 1/16/2015
8561K341 McMaster-Carr PPO Plastic 3/8" Thick, 12"x12" 1 35.52 35.52 1/26/2015
B0037Z7HQK Amazon
Max Burton Induction Cooktop
(1800W) 1 95.99 95.99 1/28/2015
In Store Home Depot 3/8"x8" Galvinized Bolts 1 10.6 10.6 1/31/2015
In Store Home Depot 3/8"x10" Galvinized Bolts 1 12.2 12.2 1/31/2015
In Store Home Depot 3/8" Galvinized Nuts 1 1.76 1.76 1/31/2015
In Store Home Depot 3/8" Galvinized Washers 1 1.76 1.76 1/31/2015
Mini Actuator Fergelli Auto.
Linear Actuator 10" Travel, 15" Tot.
Length 1 119.99 119.99 2/1/2015
dc power ad. Fergelli Auto. 12V, 12A, DC Power Adaptor 1 65 65 2/1/2015
6157K14 McMaster-Carr Clamp Collar 1/2" Shaft 2 2.65 5.3 2/3/2015
9620T22 McMaster-Carr High Voltage Wire max 600V 55A 1 24.45 24.45 2/3/2015
98596A790 McMaster-Carr Tension Pins 1/8" Dia. 1 5.6 5.6 2/3/2015
5912K4 McMaster-Carr Pillow Blocks 1/2" Shaft 2 11.11 22.22 2/4/2015
In Store Home Depot
Front
Wheels/nuts/bolts/washers/axle/etc 1 33.87 33.87 2/4/2015
AT1-AN-3A Automation Direct Inductive Proximity Sensors (5) 5 32.5 162.5 2/5/2015
In Store Home Depot Bolts/nuts/washers/lock washers 1 10.83 10.83 2/9/2015

25
9266K11 McMaster-Carr PTFE Plastic for Top of Coil Enclosure 1 18.19 18.19 2/12/2015
In Store Home Depot 14 Guage Wire (50 ft) 1 10.47 10.47 2/14/2015
In Store Home Depot Digital Multimeter 1 19.99 19.99 2/14/2015
In Store Home Depot Glass Cutter 1 2 2 2/14/2015
In Store Home Depot 3" PVC Cap 2 3.95 7.9 2/14/2015
In Store Home Depot Screws 1 7.94 7.94 2/14/2015
In Store Home Depot Splice Connectors 1 8.57 8.57 2/14/2015
In Store Home Depot Ring Connectors 1 2.18 2.18 2/14/2015
In Store Home Depot 3" PVC Pipe 1 8.8 8.8 2/14/2015
43210000 Amazon Solderless Breadboard 1 8 8 3/15/2015
AT91SAM3X8E Amazon Arduino Due 1 51.44 51.44 3/15/2015
8-CH Amazon SainSmart 8Channel Relay Module 1 14.04 14.04 3/15/2015
SJ02G-
0500300U Amazon 5V 3A Power Supply 1 17.16 17.16 3/15/2015
AT1-AN-3A Automation Direct Inductive Proximity Sensor 4 32.5 130 3/31/2015
In Store Lowes 1/4"-20x1" Bolts 1 2.48 2.48 4/2/2015
In Store Lowes 1/4"-20-3/4" Bolts 1 2.48 2.48 4/2/2015
191 AdaFruit Arduino Mega 2560 1 45.95 45.95 4/2/2015
826 AdaFruit 40x Male/Female Jumper Wires 1 3.95 3.95 4/2/2015
AT1-AN-3A Automation Direct Inductive Proximity Sensor 2 65 130 4/7/2015
NBF-3206 Amazon Electrical Box 1 33.5 33.5 4/8/2015
AN-184 Amazon Rubber Grommet, 180-piece 1 9.69 9.69 4/8/2015
2276T73 McMaster-Carr 2" Diameter Conveyor Roller 1 10.23 10.23 4/9/2015
8975K596 McMaster-Carr 1"x1/4"x6' 6061 Aluminum 1 14.24 14.24 4/9/2015
9433K47 McMaster-Carr 2.5"x0.5"OD Stainless Springs 1 6.87 6.87 4/9/2015
In Store Lowes Masking Tape 1 2.98 2.98 4/10/2015
In Store Lowes Electric Tape 1 1.99 1.99 4/10/2015
In Store Lowes Nylon Spacers 1 4.48 4.48 4/10/2015
In Store Lowes Washers 1 0.56 0.56 4/10/2015
In Store Lowes Nuts 1 0.8 0.8 4/10/2015
In Store Lowes Bolts 1 13.06 13.06 4/10/2015
In Store Lowes Carrying Handles 1 6.98 6.98 4/10/2015
8-CH Amazon SainSmart 8Channel Relay Module 1 13.18 13.18 4/11/2015
SJ02G-
0500300U Amazon 5V 3A Power Supply 1 17.16 17.16 4/11/2015
874 AdaFruit 22AWG Hook Up Wire Set 1 15.95 15.95 4/12/2015
1311 AdaFruit 3 5-Wire Block Connector 1 4.95 4.95 4/12/2015
In Store Radio Shack Small Wire Clips 1 5.38 5.38 4/13/2015
In Store Radio Shack Cable Clips 2 5.84 11.68 4/13/2015
In Store Radio Shack 12VDC Fan 1 53.97 53.97 4/13/2015
In Store Radio Shack Spiral Cable Wrap 1 6.74 6.74 4/13/2015
In Store Radio Shack 3/4" Wire Wrap 5ft 1 6.75 6.75 4/13/2015

26
45121500 Amazon Remote Power Strip 2 19.99 39.98 4/15/2015
28015 Parallax PING Ultrasonic Sensor 1 29.99 29.99 4/17/2015
805-00007 Parallax Arduino USB Cable 1 4.99 4.99 4/17/2015
8657K812 McMaster-Carr
1/8"-48"x48" LDPE Polyehtylene
Sheet 1 35.2 35.2 4/19/2015
AU11404 Barska GLX Green 5mW Laser 1 125.92 125.92 4/19/2015
N/A N/A Misc. Shipping and Tax 1 281.47 281.47 N/A
Total Spent Remaining Budget
2603.23 2396.77

27
X. Appendix B
Table 10: Needs and Specifications List
Stakeholder Concern Quote From Stakeholder Priority Description Metric Marginal Value Ideal Value
SFS Accuracy
"One missed weld can comprimise the integrity of the
entire roof"
1 Locate the membrane plates Failure Rate (Percentage) ≤ 10% 0%
SFS Accuracy
"Weld strength and induction plate alignment go hand in
hand"
1 Locate the center of the membrane plates
Distance Off Centered
(Inches)
≤ 1/2" 0"
SFS Accuracy
entire roof"
1 Heat the membrane plates after locating Failure Rate (Percentage) 0% 0%
SFS Quality "The current optimum heating temperature is 220 °C" 1 Sufficiently heat PVC membrane plates Heating Temperature (°C) 220 °C 220 °C
SFS Quality
"The strongest pull test results occur when the
membrane is evenly adhered to the plate"
1 Evenly heat PVC membrane plates
Appearance of Tensile
Tested Plate
≤ 10% Horshoe Uniform
SFS Quality
"The device is currently FM approved for a 583 lbf
tensile force"
1
Evenly and Sufficiently heat PVC
membrane plates
Tensile Load Strength (lbf) 583 lbf > 583 lbf
SFS Quality
"Sometimes the device will leave burn marks on the
white membrane"
1
Heat the PVC membrane plates without
damaging the membrane
Appearance of Membrane
Slightly burnt or
discolored
Pristene
SFS Budget
"The current device is fairly expensive for most
customers"
1 Create a prototype which is more affordable Cost w/o Labor ($) ≤ $5000 ≤ $5000
Contractor Time
"If the device is slowing us down then we would rather
just do it by hand"
1 Quickly locate the center membrane plates
Reduction Rate
(percentage)
< 25% ≥ 25%
Contractor Time
just do it by hand"
1
Quickly locate the center of angled or
recessed membrane plates
Reduction Rate
(percentage)
< 25% ≥ 25%
Contractor Time
just do it by hand"
1 Quickly heat the membrane plates Heating Time (s) 15 s ≤ T < 6 s ≤ 6 s
Contractor Time
just do it by hand"
1 Reduce job time
Reduction Rate
(percentage)
< 25% ≥ 25%
Contractor
User
Friendliness
"The simpler it is the better" 1 Easy to setup
Number of Required User
Input Settings
5 3
Contractor
User
Friendliness
"It would be nice to be able to train new guys to use this
device in a short amount of time"
1 Intuiative Prior Knowledge Needed Some None
Contractor
User
Friendliness
"If the current device does not weld the plates are not
marked, making it harder to come back and fixe them"
1 Visibly indicate every good or bad weld
Is Mark Noticable on
Worksite
No Yes
Contractor
User
Friendliness
"We have to not only manuever the device but also cary
it onto the roof"
1 Easily lifted/moved Weight (lbs) ≤ 50 lbs ≤ 25 lbs
Owner Durability
"This tool needs to at least hold up to some bumping
and banging"
1 Durable Load Bearing Strength (lbf) 200 lbf > 250 lbf
Contractor Durability
"This tool needs to at least hold up to some bumping
and banging"
1 Durable Impact Strength (lbf) 30 lbf > 50 lbf
Contractor Durability
"We rather not take time to cover or put away things if
we can help it"
1 Durable
Degree of Water
Protection
Water Resistant Water Proof
Contractor Appearance
"It is unfortunate to have to spend money on a brand
new roof that is dirty and marked"
1 Prestene roof appearance Is Mark None Permanant No Yes
SFS Accuracy
entire roof"
2
Locate membrane plates regardles of plate
orientation or recess
Failure Rate (Percentage) ≤ 10% 0%
SFS Accuracy
entire roof"
2
orientation
Membrane Plate Angle
(Degrees)
0° ≤ 15°
SFS Accuracy
entire roof"
2
recess
Membrane Plate Depth
(Inches)
0" ≤ 0"
SFS Accuracy
"Weld strength and induction plate alignment go hand in
hand"
2
Locate the center of membrane plates
regardless of orientation or recess
Distance Off Centered
(Inches)
≤ 1/2" 0"
Green - achieved
Red – not achieved
Blue – not proven

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