Prototype5 report

1. Aerocom
Portable Military Quadcopter
2/27/15
Prototype 5 Report
Introduction
During field operations, military personnel use radio devices to communicate when
they need assistance. However, mountainous terrain or urban structures can sometimes block
these radio signals, resulting in unheard distress calls. The challenge from the project
sponsor, Northrop Grumman, was to create a device that allows wireless communication,
regardless of the surroundings, by elevating a communication relay to a sufficient altitude to
obtain line­of­sight. The hope is that, using the device we design, a field operator will never be
without an emergency method for communication. The following design constraints
accompanied the assignment of our project:
● It must lift a payload of no less than 1 kg
● It must be man­portable
● It must be able to actively maintain its position in space with an error margin of a 10
meter radius sphere
● It must be able to adjust its altitude
● It must have controllable positions
● It must have a backup parachute triggered in the case of system failure
● It must be quiet
● It must be reusable
● It must cost no more than $500
To solve this problem while following all design constraints as closely as possible, we
have designed a compact quadcopter that improves communication by carrying a relay to the
required height to establish line­of­sight.
After constructing and testing a working prototype 3 as well as a further functional
prototype 4, prototype 5 emphasized the remaining requirement (controllable positions
through the use of flight control software and GPS implementation) and improving on areas
not directly critical to the specified design requirements. The goals for prototype 5, which were
delegated to newly formed subgroups, were as follows:
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2. ● Perform a comprehensive materials study to obtain strength­to­weight ratio data as
well as strength­to­weight­to­cost ratio data on various potential candidates for frame
construction
● Narrow down studied materials to a few promising options and to run comprehensive
FEA analysis to determine an optimal thickness to failure test
● Begin the failure testing process so that a final informed decision can be made early
on for the final prototype’s arm construction and body panel construction
● Prototype parachute deployment concepts
● Qualitatively evaluate the feasibility of a small parachute with the given quadcopter
weight and to order a larger parachute (if deemed necessary) to test and implement
for the final prototype
● Research and utilize the selected open­source flight control software’s onboard
auto­tuning feature to allow even better stabilization during flight
● Test and verify the GPS fly­to­waypoint system
After deliberation, previously discussed possible goals such as increasing propeller
ease­of­removal and the implementation of a safety cage around each of the propellers were
dropped. It was decided that though the propellers must be stored separately and therefore
screwed on and off for use and storage respectively, it is not an unreasonably
time­consuming task, and the need to perform that task does not strongly influence the
system’s ease of use. If time permits, a potential quick release design will be tested. However,
it is doubtful that it will be implemented, seeing as it adds complexity to the system and is not
crucial to the design requirements.
Our sponsor suggested the idea of a safety cage for the propellers to prevent damage
to the propellers and objects or people around it (see Figure 1). Though the merit of such a
component is understood, we find
the cages unnecessary and
unwieldy given the current design
and the ways in which the
quadcopter is intended to be used.
Because it is supposed to be an
outdoor­use device that is primarily
meant to ascend, hover at altitude,
and then descend, crashing into
obstacles from poor piloting is not
something that is a particularly
pressing concern (especially since
most of the flying will be
autonomous). Furthermore, the
ability to catch the quadcopter in
one’s hand is not a desired
feature, especially when the ground
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3. provides a much safer landing area. The cages would also increase both the mass and
volume of the quadcopter, an undesirable addition when we are trying to create a compact
device. On top of those reasons, the addition of a safety shield would take away the ability of
the quadcopter to easily fold away into a storage position through the removal of
quick­release pins. Either the permanently attached safety cages around the propellers would
get in each other’s way when folding into the storage position, or the safety cages would have
to be bolted on and removable by disassembling them and storing them separately. Either
way, the safety shields negate the critical aspect of quick deployment.
Basic Design and Justifications
The basic electronic design of this system is straightforward. As seen below in Figure
2, power is drawn from a suitable, onboard Lithium­Polymer battery. This power is distributed
to the four electronic speed controllers (ESCs) through the aptly­named power distribution
board. The ESC’s input low­voltage pulse­width­modulated signals from the flight controller
and the current from the battery and output a periodic, sequential pulse to the three leads to
the motors. The brushless DC motors then turn the propellers, forcing air downwards and
providing lift.
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4. The flight controller, with the installed ArduCopter V3.2.1 Quad software, has all the
programming necessary to read inputs from the GPS module, the accelerometer, the
compass, and the gyroscope, as well as the inputs from the receiver. It then calculates what
in­flight adjustments must be made to perform the desired action (i.e. stabilize, loiter,
fly­to­waypoint, return­to­land, etc.) and outputs the proper signals to the ESCs to make the
quadcopter perform that action. The flight commands can be manually controlled via a
9­channel transmitter, or command can be delegated to the AI by selecting the appropriate
flight mode on the transmitter. With the proper components, setup, and calibration, the
software also has the capacity to allow control from a smartphone with the associated
application installed and synced.
Supporting Calculations, Simulations, and Analysis for Original Design
The following simulations and analyses were performed in during work on previous
iterations of the device and have been discussed in earlier reports. However, these tests and
calculations are critical for understanding the design choices we have made up to this point.
We will further analyze these testing processes and discuss how they lay the groundwork for
the significant improvements we have made on Prototype 5.
Frame Material Simulation and Testing
In preliminary design phases, we performed FEA simulations on our frame
design in order to verify that the frame would withstand the forces due to the
motor/propeller assembly as well as the weight of the payload. In particular, these
simulations tested and verified our chosen frame geometry.
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5. Figure 3: Original Geometry Shown in MDF frame in Operating Position
Figure 4: FEA Simulation of original geometry
As seen in Figure 4, the
critical areas for failure occur at the
juncture of the arms and the main
frame when forces representing the
motor/propeller assembly and the
maximum payload were applied.
However, the von Mises stress shown
are not sufficient for failure to occur in
the given situation. We verified this
simulation by performing testing on a
single arm frame assembly. By
attaching weights to the arm and
recording the force under which the
assembly failed as well as the exact
place where it failed, we were able to
see that the simulation matched the
actual failure of the arm. Breakage
occurred in the same location as in
Figure 4.
While the material of the frame
and the geometry of the arm and arm
connection will be different for our
final design, we have found this
process of material selection, FEA
simulation, and physical verification
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6. crucial to our design process. Much of our design depends on aspects of our frame
design. Therefore having a reliable simulation and testing method is valuable, ensuring
that we can quickly and accurately determine whether a specific material and
geometry will work. As we will discuss in the next section, this process was repeated
multiple times for Prototype 5.
Propeller Testing
For propeller testing, the motor and propeller were fastened to the end of an
aluminum extruded bar,
which was vertically
attached to a wooden block
and the motor using slightly
modified aluminum
L­brackets originally meant
to attach two aluminum
extruded bars
perpendicularly. The ESC,
the battery, the battery
wattmeter and voltage
analyzer, and the receiver
were placed on top of the
wooden block. We obtained
a scale and attached the test
assembly to the platform of
the scale. The scale was
then attached securely to a
workbench (see Figure 5).
After testing 6
different propellers this way,
we compared the results for
lift vs. current (see Figure 6)
and determined that the 12
inch, 6 inch pitch propeller
was the best choice due to
its high lift:current ratio.
Even after further
experimentation, including
testing with carbon fiber
propellers, we have decided to
continue using the plastic 12x6 propellers as they are more easily replaced if damaged
than expensive materials. The carbon fiber propellers showed negligible difference in
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7. lift:current ratio. For this reason, we will consider this our final design decision and will
not continue the discussion of propeller choice in Prototype 5.
Motor and Battery Life Testing
To test the life of our Lithium­Polymer battery when the quadcopter must
support a payload, we performed flight testing with a 1.1 kg payload. This mass
represents 110% of the maximum weight required to be carried by the device. We
recorded the initial amount of charge in the battery, then began flight testing. We
began timing when the payload left the ground and stopped timing when the payload
landed again. The charge used during transient periods of flight was considered
negligible. The quadcopter was flown for 120 seconds, then flown again for 60
seconds. Each time, the amount of charge left in the battery was recorded. As seen in
Table 1, the battery had 35% charge remaining after the initial 120 second flight and
15% remaining after the second (60 second) flight.
Time (seconds) Charge Usage (% of overall
charge)
120 35%
60 15%
Table 1: Initial Battery Testing Results
These flight tests revealed some quirks about our flight modes that needed
further testing in order to understand. We predicted that a calibration error was the
source of the slight jerking in the air, and we were able to further test and verify this
during our tests on Prototype 5.
For our purposes, the quadcopter only needs to remain in the air long enough
to reach the desired altitude, allow the individual to broadcast a brief message, and
return to the ground. Because of these stipulations, we consider the battery life used
during these flight tests to be successful. Additionally, we plan to further decrease the
overall mass of the device by implementing a lighter frame. This decrease should
allow for increased battery life during flight. The battery life will be tested again once
this new frame, as well as all other modifications, have been implemented.
Competing Products
As is commonly known, the military have been using unmanned technology more and
more as advances allow more complex operations to be performed without putting a human in
harm’s way. That being said, no portable, individually deployed product is currently used to for
specific purpose that was outlined above. However, quadcopters similar to our design are
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8. commonly used for surveillance and reconnaissance purposes when a small, quiet device is
required that has the option to remain still in the air and also maneuver around or above
potential obstacles. These quadcopters are also capable of being fitted with custom payloads.
1. Aeryon Scout™
The Aeryon Scout™ is produced, along with the larger and more robust Aeryon
SkyRanger™, by Aeryon Labs Inc. and features some incredible feats of design. From its
data sheet, it has an operational range of 3 km or up to 25 minutes, and can fly up to 450m
above the ground. It weighs, without a payload, 1.4 kg and is made from predominantly
polycarbonate. It is fully GPS waypoint programmable and features a smart touchpad
interface as a transmitter, which also displays real­time camera data. The camera may be
swapped out for a custom payload. The arms of the quadcopter pop out for storage and the
battery pops out for quick replacement. The more robust model, the SkyRanger™, folds
downward into a compact design that fits into a custom backpack. The plates underneath the
propellers and on the side of the main body are actually fins meant to regulate internal
temperatures. Although these quadcopters feature characteristics that resemble our chosen
design, ​ours is likely an order of magnitude (if not two) less expensive, is lighter, and
likely can support a heavier payload relative to its own unencumbered weight.
Sources: http://www.dtwc.com/sites/default/files/datasheet/Datron_Unmanned­Solutions.pdf
https://vimeo.com/58547229
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2. XAircraft X650 Pro
The XAircraft X650 Pro is another quadcopter that has potentially been used for
military purposes. It has a flight time of 20 minutes and a maximum weight (when
encumbered with a maximum payload) of 3 kg. Its arms fold horizontally into a slightly more
portable position for storage such that they look like an “H” when viewed from the top. This
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10. quadcopter as shown can be fitted with a Hero™ camera, and ​is priced at roughly double
the cost of our design.
Sources: ​http://www.xaircraft.com/products/x650­pro­2/
http://download.xaircraft.com/manuals/XAircraft%20X650%20Pro%20User%20Manual%201.
0.pdf
Justifications for our Design Over Competitors
The quadcopters discussed above represent two of the three categories of
quadcopters. The first is the stunningly capable and stunningly expensive military­grade
quadcopter, the second is the moderately priced but well­engineered quadcopter. The
category not represented above is the cheap and cheaply manufactured quadcopter for short
duration consumer use. Our design is a member of the second category due to its various
features (including folding arms for portability and storage, quick battery exchange, and
payload­ready lift characteristics), but is unique in that it is not nearly as costly as quadcopters
with similar performance characteristics. On the basis of reduced cost, our design is the most
useful for Northrop Grumman and for the US Military for the application we are designing for.
Significant Improvements of Prototype 5
Prototype 5 possesses a number of features that are improvements over previous
prototypes, including a new frame construction choices based on a comprehensive study of
various types of materials, testing of a parachute deployment system and building of a new
parachute, as well as research and utilization of our open­source flight control software’s
onboard auto­tuning feature.
The first of these improvements is the significant work done to select, model, analyze,
and test different materials to determine the best strength to weight ratio, accounting for cost.
The first step in this process was to perform a comprehensive materials study. Many
commonly available thermoplastics were examined, along with some inexpensive metals.
Woods were avoided due to their anisotropy, and plywood was avoided because it is poorly
documented in terms of strength and it is generally expensive compared to the other options.
After preliminary research, a strength­to­weight ratio table was formed (see Figure 7).
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Although this analysis yielded very useful results, a simple strength analysis is not
sufficient for decisions made in an engineering project. Therefore, the cost of the material in a
size standardized over all the samples was recorded, and a strength­to­weight­to­cost ratio
analysis was performed. Although this is not a common measurement, and in this case was
not perfectly standardized, it presented telling trends about what is best suited for an
application where budget is an important factor. See Figure 8 for the tabulated results of this
analysis. It is clear that, though there are very strong plastics with suitable mechanical
properties, they are far too expensive to use when only slightly weaker materials are
significantly less expensive, like the Nylon 6/6 and the Acrylic. Furthermore, because
aluminum (6061 T6) is common, easy to obtain, and has the strength of a metal, it had
highest value according to the usefulness per dollar metric used for all the examined
materials.
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12.
Figure 8​: Strength­to­Weight­to­Cost Ratio Analysis
Based on the results of the analysis, it was decided that Nylon 6/6, Acrylic, and
aluminum would be the materials to be tested for the next phase of design. The extent to
which materials were applied for this prototype is with initial testing that will be discussed
further in the testing section of this report. It was decided, after feedback from the design jury
along with recommendations from Phil and background knowledge about composites and
I­beam construction, that the first test would utilize the strength of aluminum in a composite
form. Because aluminum is so strong compared to the applied loads, it has the potential to be
used in extremely thin sheets.
The practical issue with this material is that when spread apart by a certain distance,
thin aluminum sheets will deform in undesirable ways way before it can utilize its strength
properties. To solve this issue, either an I­beam construction must be formed or a composite
made such that the aluminum sheet is forced to behave like a solid sample in bending. Due to
how thin the aluminum can potentially be (and was for the test), the more reasonable solution
in terms of manufacturing was to form a composite (see Figure 9). To do this, the thin (0.016
in thickness) aluminum sheet was adhered to both sides of a relatively sturdy polystyrene
foam (0.75 in thickness). This way, the aluminum was sufficiently spread out to support the
bending moment from being cantilevered, but was also forced to deform like a solid,
continuous body.
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13.
Figure 9: Aluminum Composite Concept
Because the area of highest stress on the entire quadcopter is on the quad arm
connection to the base, that was the area of focus for the materials selection process for this
prototype.
Parachute
In response to our sponsors preferences, we have implemented our parachute design
for Prototype 5. For our parachute design, we wanted to incorporate two features: manual
deployment and automatic deployment in the case of battery failure. A rubber band holds the
parachute on top of the quadcopter and is attached on two ends, as seen in Figure 10. On
one end, the rubber band is held by a solenoid that releases the rubber band (when the
battery dies), allowing the parachute to unfold. On the other end, the rubber band is held by a
servo motor, which is controlled manually by the transmitter. As a knob on the transmitter is
turned, the servo head turns, releasing the rubber band and allowing the parachute to open.
This way, even if the battery unexpectedly loses power or one of the motors or propellers
break, the quadcopter can be recovered without the destruction of the entire unit. Additionally,
the manual parachute feature is controlled via knob (as opposed to a switch). This way, the
knob has to be turned significantly before the servo motor will release the parachute, avoiding
possible accidental releases by inadvertently hitting a switch. Additionally, a servo motor was
used because the flight controller outputs PWM, and we have yet to determine how to
connect a solenoid using the PWM outputs (the solenoid on the right of Figure 10 is directly
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14. attached to the battery). Nonetheless, we used a smaller servo motor that works just as well
as the bigger servo and is significantly lighter.
Figure 10: Parachute deployment assembly, including attached parachute
Figure 11: Parachute deployment assembly; no parachute, stainless steel attachment shown
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15.
Determining Parachute Size​:
As the quadcopter falls, we want it to reach a certain constant terminal velocity (no
acceleration). Thus, we set drag force equal to . According to online resources,ass x gravitym
the drag coefficient for nylon is 0.75 and by predicting the quadcopter’s terminal velocity
speed to be about 5.2 m/s, we calculated the needed area of the parachute. For this reason,
we ordered a 60” diameter nylon umbrella to make into a parachute. This new, larger
parachute must still be tested to determine the drag coefficient. This will involve dropping the
parachute with an attached load from a substantial height such that the distance required
before the load and parachute reach terminal velocity is negligible compared to the total
distance. Knowing the height and calculating the constant velocity by measuring time, the
drag coefficient can be calculated to be used to verify the drag force of the parachute at
certain speeds.
Estimated mass for prototype 6 = 2.2 kg (with payload)
.2 x 9.8Fd = 2
ensity 1.2 kg/md = 3
.75Cd = 0
elocity (assumed) 5.2 m/sv =
Plugging these numbers into the drag force equation, the diameter is estimated to be
59.1 in. After testing this parachute, we may look at going up to the next size (70 in) in order
to have a more manageable descending velocity, as 5.2 m/s is a relatively high speed.
Flight Modes:
We attempted to enable GPS­based flight modes for Prototype 5. Three flight modes
would be used: stabilize, loiter, and auto. The stabilize mode would allow for manual control of
the quadcopter while the device self­levels the roll and pitch axes. This is the mode we have
used for most of our tests thus far. It requires the most involvement and piloting skill, and we
would like to enable other flight modes in order to reduce the complexity of operation for the
end­user. The loiter mode attempts to automatically maintain the quadcopter’s current
location, heading, and altitude. The pilot may still control the quadcopter manually, but once
the controls are released, the quadcopter will hold its position. This flight mode would be
useful for keeping the quadcopter in a specific location after manually positioning it, and it
would reduce drift caused by factors such as wind or operator error. Auto mode controls the
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16. quadcopter autonomously and routes it through pre­programmed waypoints. This mode is
desired for the greatest ease­of­use because the user will be able to send the quadcopter to a
specified position for a desired length of time with little to no piloting skill. Unfortunately, we
were not able to successfully implement different flight modes for this prototype. Due to
inclement weather, the amount of time we were able to perform flight tests was less than
ideal. However, we did perform a number of trials detailed under the Testing and Analysis
section.
Testing and Analysis
The testing of the composite aluminum­polystyrene­foam arm went successfully. As
the aluminum used was almost as thin as can be purchased without risking immediate tearing
by hand, the results were not expected to match simulation data. However, the aluminum
performed better than expected. See Figure 12 for a Solidworks FEA simulation that was
performed on the composite arm under flight loading maximum conditions. As shown, the
maximum Von Mises stress experienced in the aluminum sheet is about 15 MPa
(megaPascals), where the yield strength of that composition and heat treatment of aluminum
typically has a mean value of 275 MPa. So, assuming the assumptions made in simulation,
this arm would perform far better than the MDF arm and likely far better than the alternatives.
Unfortunately, we will soon see that the the assumptions made by the simulation were not all
valid. Along with the great load­bearing characteristics of the arm in simulation, it was also
estimated to have a mass of 18 grams, nearly half of the mass of the MDF quad arms.
Figure 12: Composite quad arm simulation under ideal flight conditions
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After simulation, the arm was assembled. In order to adhere the “plys”, a 5 minute
epoxy was mixed and spread on the aluminum arms before firmly sticking them to the foam.
After a day of curing, the arm was ready to test. At first, the same protocol was followed from
when the first quad arms were tested: it was bolted down and sandwiched between two
stronger pieces of plywood. Unfortunately, the foam rapidly gave way upon tightening the
bolts. It was decided that this design could only be feasible if a small, more rigid component
was placed at the base (and at the motor mounting point when flight testing occurs) to
facilitate the ability to tighten the assembly down. After this modification, the arm was ready to
test.
A bolted­in plywood insert was used to maintain rigidity at the mounting point, and the
insert was then clamped down firmly to a table. Small notches were cut into the aluminum on
the sides at the loading point so a string could be hung, with a basket containing known
weights suspended on the other end (see Figure 13). Under the basket, after 4 inches of room
to allow deformation, was a stool to keep the weights from falling and potentially cracking.
This was the same testing protocol used for previous failure tests.
Figure 13: Failure Test Assembly for Composite Arm
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Weights were then incrementally added to the basket, and the system was given time
to deform. We quickly noted that though this arm was lighted than the tested MDF arms, it
deformed less at the same weights and very quickly surpassed the MDF arms in terms of
maximum supported load. Finally, the arm failed after supporting 5.3 kg (see Figure 14),
which not only is nearly double the weight supported by the MDF arm, but nearly double the
entire weight of the quadcopter with payload!
Analysis of the quad arm yields interesting results. As seen in the same figure below,
the arm failed through thin “column” buckling of the bottom aluminum ply in compression. This
is where the simulation could not simulate properly. Since column buckling typically occurs at
a slight, potentially imperceptible inhomogeneity in the material, the simulation cannot
simulate the actual situation well. The real reason the arm failed, however, was the foam.
Ideally, if the foam were harder and more rigid, buckling failure would be postponed to an
even higher applied load, if not negated completely.
Figure 14: Failure Mode of the Composite Arm
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19. As it stands, even though the arm failed in an easily remedied way, it supported a far
greater load than would ever be experienced (with the exception of a crash) in common
usage. Even so, it was recommended that a thin layer of crushed fiberglass and resin be
applied to the sides. This would only add a gram or two to the weight of the arm, but
significantly increase the rigidity of the arm, providing a better connection between the top and
bottom aluminum sheets, and possibly delaying buckling failure in a way similar to how using
a more rigid foam would. This addition would also improve the overall aesthetics of the frame.
The overwhelming success of the failure test of the composite arm lessened the
importance of spending time to test other materials in a similar manner. Since the 6061 T6
aluminum had one of the best strength­to­weight ratios as well as the best
strength­to­weight­to­cost ratio, we deemed it unnecessary to test other quad arm concepts
through a similar process. Unfortunately, this construction is not nearly as feasible for the
main quad body. In that case, a thicker but lighter engineering plastic will be used. One­eighth
inch thick acrylic is one option proven to work (see Figure 15) and is readily available, though
further testing and simulation will reveal whether or not nylon can perform similarly well, if not
better, and if the thickness can be reduced to better minimize the frame weight.
Figure 15: ⅛” Acrylic Body Concept Simulation
Our preliminary flight mode test consisted of attempting to activate the quadcopter’s
loiter mode while tethered and flying just 2­3 meters from the ground. After switching from
stabilize mode to loiter mode, the quadcopter began moving erratically, darting back and forth
and oscillating uncontrollably. Initially this inconsistency was thought to be the fault of the
GPS module, but after examining the GPS coordinates we found that the margin of error for
the GPS fix was relatively small and unwavering. Instead, this undesired behavior was caused
by improperly calibrated PID parameters found in the advanced settings for the flight
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20. controller software. We could have attempted to manually calibrate these values by using the
flight controller’s built­in functionality for storing PID data, but this would have required
guesswork and repeated flight tests to check each minor change to the parameters. There
exists an autotune feature present within the mission planner software that can automatically
adjust the PID parameters for greatest response. Autotune works by automatically twitching
the quadcopter in various directions and measuring the observed response with its sensors.
In order to utilize this feature, we had to fly the quadcopter untethered and further from the
ground. We took proper safety precautions by performing this in a large, open field with no
bystanders present and distancing ourselves from the quadcopter. Unfortunately, it was rather
windy during our first opportunity to try the autotune procedure. After achieving the necessary
altitude, the wind began to carry the quadcopter beyond the control of our limited piloting
experience. Though we attempted to land immediately, the quadcopter suffered a minor
impact and one of its arms broke. Luckily there were no other consequences, but as a result
we were unable to complete the autotune procedure or enable flight modes.
Final Plans
Remaining Requirements:
The only steps that need to be taken for the final design of our quadcopter include
perfecting the use of the flight mode software and GPS flight controls as well as making a final
decision about materials and construction and then implementing them.
Given the snowy weather which limited our testing, we didn’t have enough time since
our last report to fully implement the flight mode controls. Once we are able to test and verify
these flight modes, all requirements will be fulfilled.
Design Tweaks Required:
­ Improve manipulability of parachute system setup
­ Test newly constructed parachute
­ Implement new frame materials and geometry
­ Improve usage of flight mode software and GPS system to attain automatic control
Final testing Required for Completion
As discussed in “Remaining Requirements,” we need to perform further flight
testing with implementation of the GPS flight modes. Additionally, testing needs to be
done on the functionality of the parachute we constructed as well as the parachute
system as a whole, including both the battery fail­safe and the manual deployment
sides. Finally, a flight test with payload using the selected materials must be
performed, though given the extensive analysis and testing that went into materials
selection, this should not pose a problem.
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21. Implementation Plan for Device
The implementation of our device is dependent on its functionality and its
capabilities in terms of GPS reliability and sturdiness in the final design. Our sponsors
provided only preliminary requirements in terms of the overall goals of a device such
as ours, stating that our device must only reach a height of 10 meters under ideal
weather conditions. We are also making our design as light and portable as possible
to increase ease of use regardless of specific implementation.
Opinion of Team Progress
We have experienced success as a team, thus far, experiencing no obstacles
that we have found impossible to overcome. We have been able to work well as team.
Our recent division into subgroups for Prototype 5 enabled us to all contribute
concretely and efficiently to the design, building, and testing of aspects of the
quadcopter. Our sponsors have expressed their appreciation for the hard work of our
group and optimism for the overall outcome of design.
Bill of Materials
Item Cost ($)
Spent to date 647
Assorted bolts for sturdier motor attachment ­­ purchased by ME dept.
Parachute assembly materials 11
Future costs: dependent on availability of
aluminum and foam for new
frame, as of now, already
available through department
Total 658
Budget
Given budget for single, assembled quadcopter: ​$500
Total money spent by group thus far:​ $658
We are $158 over our given budget of $500. However, this is due to our choice to
purchase additional electronics components in the case of failure, damage, or faulty parts as
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22. well as our experimentation with parts and alternative materials. The overall cost of the parts
currently in use by the quadcopter is less than the $500 limit, and therefore, meets the
requirement of a device costing less than $500.
Video of Functioning Prototype 5
https://www.youtube.com/watch?v=S8EXqIeXXf4
Appendices
Updated Timeline:
Iteration (due date) Task Status
Prototype 4 (1/29) Complete redesign of frame
arm geometry, new laser cut
complete
Perform flight testing complete
Design and build
payload/battery container
battery container
constructed; exact payload
specs to be determined
Critical Design Review (2/6) Update on design decisions complete
Discuss progress and goals
to further affirm and/or
modify direction of project
complete, received positive
sponsor feedback, evaluated
decisions
Prototype 5 (2/26) Build landing legs incomplete: will instead be
using battery/payload
container as landing cushion
Determine electronics
attachments
complete; holes drilled in
frame for permanent
attachment
Determine other frame
choices; modify
complete materials study;
frame design planned; new
frame yet to be implemented
Implement parachute complete
Improve ease of propeller
use
After study, not very
feasible; would decrease
robustness of design as
22

23. propellers would be less
secure
Prototype 6 (4/9) Fine­tune frame design incomplete
Improve GPS usage final state incomplete;
continuous work required
Alternative transmitter
(phone)
Potential: feasibility to be
determined after further
research and testing
Submit report with complete
analysis including detailed
CAD, computational models,
and dimensioned design
drawings
incomplete
Design Day (4/20) Presentation and
demonstration of final
quadcopter design (video)
incomplete
Sources:
Arducopter. “Flight Modes.”
http://copter.ardupilot.com/wiki/flying­arducopter/flight­modes/
DIY Drones. “Automatic parachute drop.”
http://diydrones.com/profiles/blogs/it­works­fully­automated­parachute­drop­from­quad
copter
NASA. “Terminal Velocity.”
http://exploration.grc.nasa.gov/education/rocket/termvr.html
World Transactions on Engineering and Technology Education. “The determination of
aerodynamic drag force.”
http://www.wiete.com.au/journals/WTE&TE/Pages/Vol.6,%20No.1%20(2007)/21_Njoc
kLibii20.pdf
23

24.
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