Fall
2008
Design Report
Tim Palmer, Matt Cerro, Mark Pennington,
Eli Henson, Nick Yankee, Achala Akuretiya,
David Mehaffey
robo-horizon@uidaho.edu
Contents
Executive Summary....................................................................................................................................... 3
Background ................................................................................................................................................... 4
Problem Definition ........................................................................................................................................ 5
Concept Development .................................................................................................................................. 6
Concepts Generated ..................................................................................................................................... 7
Catapult ..................................................................................................................................................... 7
Electromagnetic Launcher (EML) .............................................................................................................. 9
Sling ......................................................................................................................................................... 10
Concept Selection ....................................................................................................................................... 12
Product Description .................................................................................................................................... 13
Launching Process ....................................................................................................................................... 13
Control System ............................................................................................................................................ 14
Product Evaluation ...................................................................................................................................... 15
Economic Analysis ....................................................................................................................................... 16
Conclusion and Recommendations ............................................................................................................ 17
Appendix A .................................................................................................................................................. 19
2
Executive Summary
This report presents the design of an electromechanical catapult designed to launch
sensor to gather information on the moon. The National Aeronautics and Space Administration
(NASA) believes that hydrogen could be trapped in deep craters on the Moon’s surface. In
order to search for hydrogen, NASA plans on landing a stationary platform in one of these
craters. The craters are deep enough to prevent sunlight from reaching the crater’s bottom,
thus negating the use of solar power to run the platform and requires all components to use
power efficiently. In order to collect sample points from the surrounding terrain and keep
weight and power consumption low, NASA has charged us with developing a system which will
launch a sensor array and retrieve it for repeated use.
The design we decided on is modeled after a basic siege weapon, the catapult. There
are numerous advantages to this design including the fact that its subsystems are decoupled
and easy to troubleshoot. In addition it uses considerably less power than the other designs
considered.
A major limiting factor for the project is power consumption so we used rechargeable
batteries that maximize the available power for the system. We also used high efficiency DC
converters at numerous voltage levels to supply the minimum power needed.
In regards to our control software, there are two main points of interest. Control of the
catapult was accomplished through C code to actuate specific motors. Our power monitoring
software came with the rechargeable batteries and allows for efficient charging/discharging of
the batteries.
In regards to the control hardware, there are also two main points of interest. The
“mind” controlling all the motors is a Rabbit 4100 utilizing its multiple pulse width modulator
channels as well as standard I/O ports. The power management station is a pelican case with a
modulated computer inside as well as the power management circuit boards.
3
Background
“The Moon is the first milestone on the road to the stars.” This quote by Arthur C. Clark
captures the very essence of Robotic Horizons’ existence. Robotic Horizons, a University of
Idaho capstone design team, has been tasked by NASA to develop a device to deploy sensors
with the intent of locating hydrogen on the Moon. In the near future, NASA plans to set down a
lander into some of the deep, permanently shadowed craters on the moon. Their desire is to
take soil samples looking for hydrogen around the lander’s location. Due to limited information
regarding terrain and conditions, NASA does not expect a rover to be able to maneuver
successfully. In essence, another method is necessary to gather data from various points
around the lander. It is speculated that there is hydrogen within the dust on the Moon’s
surface. Due to the low gravity, gasses escape the atmosphere of the Moon easily. NASA wants
to search within the craters of the moon where the possibility of finding hydrogen is much
higher. The ultimate goal is to harvest hydrogen on the moon in order to create habitats
suitable for humans to work in. This would make launching missions to Mars much more
feasible as the Moon could be used as either the launching point, command point, or a staging
point. There are many more possibilities for scientific activity upon discovery of hydrogen on
the Moon.
NASA plans to land a stationary platform within one of the larger craters. This is where
the design by Robotic Horizons would be utilized. Complex devices, such as rovers, are
expensive and potentially unreliable. In order to gather valuable data as economically as
possible, Robotic Horizons has designed an Instrument Launcher – a device designed to launch,
and retrieve, a sensor up to 10 meters on Earth, 60 meters on the moon. The design will deploy
sensors throughout the crater collecting environmental samples. These sensors will use a
method, such as mass spectrometry, to search for hydrogen. The design of the sensors,
however, is not within the scope of the project.
4
Problem Definition
Neil Armstrong said, “…we're going to the moon because it's in the nature of the human
being to face challenges. It's by the nature of his deep inner soul... we're required to do these
things just as salmon swim upstream.” Yet, the challenges on the moon are not over yet. The
moon has unlimited potential. The moon can be used as a staging point for missions to Mars,
and beyond. The moon also can be used to further many kinds of research from medical to
advanced physics. NASA aims to go back to the moon relatively soon. However, such a feat is
very difficult and expensive. If there were some way to create habitats on the moon, lunar
activities would be much more possible. It is this goal of finding some source of creating an
environment suitable for humans that spawned the idea of searching for gases on the moon.
The moon’s gravity is too weak to hold an actual atmosphere, but there exists the possibility
that hydrogen is trapped within the dust on the moon in the deeper lunar craters. One obvious
solution would be rovers; however their current technology is ineffective. Rovers are unreliable
due to their high power consumption and their mobility is limited. The question then arises,
how can we search for this hydrogen? It is Robotic Horizons’ plan to build a device to send out
sensors from a stationary unit to search for the gas trapped in the lunar dust. Robotic Horizons
will be working for NASA to transform the idea of lunar habitats into reality.
Table 1 describes the objectives and outcomes more in depth. See Appendix A: House
of Quality for a complete list of design criteria.
Table 1
Proposed Objectives
Expected Outcomes
Ability to launch sensor array 60 m (lunar
Design launches sensor array 10 m (Earth
gravity)
gravity)
Ability to retrieve sensor array after
Design incorporates a tethered payload
launch
Ability to control catapult remotely
Wireless systems interface via adhoc
network
5
Long battery life
Enough battery life to execute 100
launch/retrieve cycles
Due to this mission being slated for the moon, certain constraints need to be
mentioned. The most significant cost of the final design will be weight. This means that the
cost of materials and construction are almost negligible compared to the cost of transporting
the instrument to the Moon. Also, the instrument will need to be self powered because of the
permanently shadowed nature of the craters.
With the unknown conditions in the lunar craters the Robotic Lunar Exploration
Program (RLEP), Instrument Launcher was envisioned. A device is needed to launch a sensor,
one kilogram in mass and approximately 26 cubic centimeters in volume, up to 60 meters in any
direction under lunar gravity. The current plan calls for 10 launches for the proof of concept;
the final design is required to have the capability of 100 launches or more.
Concept Development
Our design process consisted of several steps. The first was identifying the project and
completely understanding the scope, purpose, and problem the project was trying to solve.
Since there was no need to reinvent the wheel, the next step was to see what was currently on
the market and see if we could adapt anything for our project. The next step was to brainstorm
different solutions to our problem. We didn’t want to be critical of ideas during that stage; we
were simply coming up with as many ideas as possible. Once we had several design ideas, our
next step was to select three of the best ideas and research them further. We then built
several quick prototypes to better understand the potential problems with each design. Then
we decided on one idea and focused all of our energy on that. We then analyzed our design
and made necessary improvements. We continued the process of prototyping, testing,
analyzing, and making improvements until we had our final design that we presented to our
customer.
As the lander arrived at its final destination the first step was to initialize itself and
prepare to launch the sensor package. The next step was to define the targets. The options
6
included user defined targets or a predefined pattern. After the target acquisition phase, the
sensor package then loaded into the catapult arm, a distance and angle was then calculated
and translated into physical motion (catapult arm pulled back and turned to an appropriate
angle). Once all preparations for launch of the sensor were completed, the sensor package was
then deployed to the specified coordinates, collected viable data, and retrieved and prepared
for another launch.
Robotic Horizons has searched out multiple solutions to the problem of sending out
sensors from a stationary unit. Preliminary prototypes of several design ideas have already
been made. Three designs in particular have been researched further. Robotic Horizons has
built an Electromagnetic Launcher, a Sling, and a Catapult. While each of the prototypes has
their strengths and weaknesses, Robotic Horizons decided to focus their effort on the catapult
design. The catapult design had the most reliability, production feasibility, and the best ability
of electromechanical systems to be decoupled for technical problem solving.
Concepts Generated
Catapult
One of the forefront concepts the group has decided to investigate further is the
Catapult. Historically the catapult has proven to be a very effective, accurate, and efficient way
of hurling an object over a distance. With this design, instead of re-inventing the wheel, we’re
just refining an already good idea. Figure 1 shows a sketch of the initial prototype.
7
Figure 1: Catapult Prototype
What we like about the Catapult is its simplicity. Building designs and mathematical
models including the physics of a catapult are readily available. There are relatively few
variables to consider when dealing with the operation of a catapult when compared to other
concepts. As compared to the Sling model it is not limited by other objects on or around the
platform. The only power required for launching is a motor used to pull the arm back. As for
re-loading, the design makes this very simple. The very act of retracting the sensor array pulls it
back into the cup of the catapult as seen in Figure 1 (above).
Another aspect of the Catapult design is its ability to use and or interchange different
sources of launching force. The main option right now is a simple spring which will pull the arm
up rapidly. This will facilitate rapid prototype production as well as allow us to refine some of
the details of the design while minimizing complexity. In addition to the spring we are looking
into an electromagnetic design. The electromagnet would be charged very briefly producing a
very strong magnetic field which would repel another electromagnet or permanent magnet.
The final major consideration for the Catapult was the power consumption. Regardless
of whether or not the Catapult uses a spring or electromagnet, it is still projected to use a
minimal amount of power. This is a strong benefit as one of our primary design restrictions is
battery life. The equations used to calculate power for the Catapult can be found in Appendix
A, Figure 11.
8
Electromagnetic Launcher (EML)
The electromagnetic launching system was inspired by numerous different sources. Rail
guns have often been considered for explosive-free projectile launching. A favorite
demonstration of many physics departments and garage experimenters involves launching an
aluminum plate from an energized coil of wire. Many modern companies are investigating the
use of electromagnetic launchers with a similar apparatus for propelling satellites and other
space craft into orbit. We looked to these technologies and saw the opportunity to scale it into
a small, lightweight, package.
Figure 2: Electromagnetic Launcher Design
The EML concept consists of wire wound solenoid using a steel core as a highly
permeable flux path. A MOSFET controlled by a Rabbit microcontroller is used to manipulate
the discharge pulse. Multiple capacitors are connected in parallel to store the charge required
for firing the projectile. A simple DC to DC converter will be used to step up the battery voltage
to charge the capacitors to the required potential level. The projectile is guided at launch by a
short barrel protruding from the steel core. Figure 2 is an image of the EML concept. Figure 3
reflects the proposed circuit implemented in this design. Mathematical models pertaining to
the specifics of this conceptual design can be found in Appendix A, Figures 12, 13, and 14.
9
Figure 3: EML Circuit Design
The first advantage of this concept is related to energy efficiency. Due to the lack of
moving parts, frictional losses within the launcher itself are very limited. High power levels are
required for operation, but only for an extremely short duration. In this design a capacitor bank
is utilized to provide storage for the charge and to allow for a quick discharge producing the
large energy pulse. The short pulse width factors in to low average power utilization. Retrieval
and targeting power consumption are similar to the other designs. The low power
consumption meets one of our major design requirements.
Another design constraint we sought to achieve with the EML concept was accuracy and
repeatability. The purely electrical nature of the launching mechanism allows for precise
control of the projectile using a microcontroller and supporting hardware. Targeting will be
achieved with a combination of bearing control, using a motor and turntable, combined with
varying the discharge pulse width by means of a microcontroller and MOSFET. Few friction
forces present in the launcher limit the variance of each launch from ideal. This allows for
consistent control using algorithms to account for known variables and targeting instructions.
Sling
The sling design utilizes rotational momentum to launch the projectile. By maintaining a
constant angular velocity and increasing the radius between the load and the center of
rotation, a significant amount of energy can be stored. This design could also launch multiple
10
projectiles at one time in a random pattern. Mathematical models for sling projectile motion
can be found in Appendix A, Figures 9 and 10.
Figure 4: Sling Design
Some of the benefits of this design are the random launch pattern and the device’s
ability to throw the projectile in 360 degrees without the need of a turntable. Also it has the
benefit of simplicity. The device does not require any complex electronic aids. A simple motor
controller can increase or decrease the rotational velocity and another simple motor will reel
the tether in and out.
There are a few problems with this method. The first problem is that it requires a
considerable amount of space and would be adversely affected by obstructions near the
platform. The power cost decreases as the radius of the circle increases. A nearby obstacle
would require the device to use considerably more energy per launch due to the decreased
radius. Another problem is the device must remain level. The optimal launch angle for any
object seeking to travel the farthest distance is 45 degrees. The current sling design does not
take advantage of this and as a result requires an initial velocity over four times greater than
other designs. Figure 5 is an exploded 3D view of the current prototype sling.
11
Concept Selection
The following morphological chart, Table 2, was used to asses each alternative for
completion of the process flowchart (Appendix A, Figure 8) design. From this analysis, three
initial concepts were chosen. The sling, catapult, and EML were selected for further review.
Function
Launch
Retrieve
Deployment (set up)
(storage)
Loading (Re-loading)
Aim-controls
Target Acquisition
Launch Distance
Guidance Sensors
Communication
Method
Electromagnetic
Launcher
Catapult
Cable
Vehicle
Self Contained
Assembly
Mechanical
Magazine(Spring)
Telescoping Arm
Telescoping Arm
R/C Vehicle
(Wheels)
R/C
Vehicle
(Tracks)
Magazine
(Gravity)
Spring
Stepper Motor / Microcontroller
Trajectory
Tension
Pre-programmed points
User aim by range/direction
Mechanical
Electrical
(Spring)
Laser Range Finder
Baseline Zeroing
Wired
Wireless
(Umbilical)
Pattern
Table 2: Morphological Chart
At a team meeting three weeks prior to Senior Snap Shot Day, it was decided as a team
that the sling was not capable of meeting the standards. It used too much power and did not
make use of the optimum 45 degree launch angle. It was decided that we would discontinue
research on this concept to focus our attention on production of the Catapult and EML
prototypes.
Our first prototype of the EML did not work as expected. It attracted the dummy
projectile as opposed to repelling it. After talking to Dr. Hess, a Professor in Electrical
Engineering, it was suggested that the design could not operate with the switch used. It was
determined that a MOSFET used in place of the switch, and operating at the resonant
frequency, would make the device operate as desired. Unfortunately this idea was too complex
to be of use to us, and after much time and effort we still did not have a working prototype so it
was sidelined.
12
According to the decision matrix, the catapult design is the most viable. With this in
mind the Electrical engineers will be working on the coding and electronic controls while the
Mechanical Engineers will be working on improving the catapult design.
Catapult Electomagnetic Launcher
Complexity
5
1
Minimal Size
4
5
Launch Velocity
5
5
Aim Controls
5
5
Platform Compatability
4
4
Power
4
4
27
24
Sling
5
4
2
3
4
2
20
Table 3 Decision Matrix
Product Description
Launching Process
As stated earlier, Robotic Horizons has chosen
an electromechanical catapult. The design has been
kept as simple as possible since the availability to
troubleshoot and fix problems on the moon is limited.
Based on our conceptual design, we have built a
design that includes two upright supports, one on
each side, two mechanical springs, each connected to
an upright, and the catapult arm in the middle. A
motor pulls back the arm and holds it through a spool
and ratcheting gear system. As the pawl and ratchet
disengage, the springs pull the arm up quickly. An
advanced motion inhibitor system stops the arm at
45⁰ from its initial position. This angle will allow for
the maximum distance with the given force applied.
The sensor is then launched. The sensor is attached to
13
Figure 5 Catapult - Elevated Back View
a tether, which is, in turn, attached to a bait-casting reel system. The reel is attached to a
motor, which reels in the tether and prepares the catapult for another launch. A lever arm
actuates the release switch to allow the tether to free spool as the sensor is launched. We are
controlling the catapult wirelessly through a microcontroller interfaced with a laptop.
Control System
The control system utilizes a distributed
embedded processor design in which two separate
microcontrollers share the work. The first and
foremost microcontroller is the Rabbit 5400W
(“RCM54”). The RCM54’s primary responsibility is to
establish a wireless access point which allows other
wireless devices to connect to it. Its second job is to
provide a user control interface which converts
commands given by the user into meaningful data
streams and then sends them to the Rabbit 4100
(“RCM41”). The RCM41 is the second microcontroller
which is ultimately responsible for motor control and
sensor reading. The RCM41 utilizes RCM54 and turns
Figure 6 Control Box - Elevated Front View
certain motors to a specified position. The RCM41 then confirms that the motors have turned
correctly and informs the RCM54 of a successful (or unsuccessful) completion. The RCM54 in
turn informs the user of the status of the catapult.
The decision to use a distributed processing approach was a simple one. It allowed the
control system to reduce code complexity while increasing security and reliability. An end
result for the system would be that either microcontroller would be able to run the catapult by
itself in the event of a major failure of the other. The decision to use the Rabbit 5400W was
simple enough. It was chosen for its processing power and capability as well as for user
familiarity. The decision to use the Rabbit 4100 was a more complicated and prolonged
scenario. We originally wanted to use a Basic Stamp 2px for its ability to easily interface with
14
motor controllers. Insurmountable difficulties were encountered, however, while attempting
to get the BS2 and RCM54 to communicate. In order to complete the design, the use of the
RCM41 was used.
It was decided that there should be a control box that would act as the “Remote Control
System.” The idea was to build a computer, essentially, which can hold all the necessary
programming tools, programs, warranty information, and other team files which can be passed
on to next year’s team. The design includes a 15” touch screen and a protective case to house
all the components. It has also been speculated to use the box as the primary battery charging
station for the batteries used on the catapult.
Product Evaluation
Mechanically, the catapult behaves just as we had planned. By simply changing the springs,
controlling how far back we pull the catapult, and adjusting the weight of the payload, we can adjust the
launching distance with a high level of accuracy. The retrieval subsystem works as planned as well. By
adjusting the voltage supplied to the motor controlling the reel, we can control how fast the sensor is
pulled in. Also, we can adjust the drag on a baitcasting fishing reel. This allows us to control how much
force is opposing the sensor before the line slips. The lever arm that pushes the reel release down
works as planned as well. The ratcheting system successfully holds the arm down, keeping the force
opposing the motor to a minimum, preserving the life of the motor and allowing us to keep pulling back
the arm and releasing the arm decoupled. The base rotates 360⁰ and the stepper motor works
flawlessly. Overall, the catapult performs as expected and is a solid, durable design.
Electrically, the catapult is very sound. We can control each of the motors exactly how we want
through whatever code we decide to write. We were not, however, able to establish wireless
communications between the Rabbit and the Control Box. We also weren’t able to have a more
interactive interface. We wanted to be able to either put in points manually (one at a time or multiple
times) or have a preset pattern database to choose from. We were only able to incorporate a one point
at a time sequence. The computer behind all the programming is top of the line and can hold its own as
technology continues to advance.
The catapult meets the launching distance requirement of 10 meters on Earth. This was tested
by simply launching half a pound weight and seeing how far it went. The catapult has a full 360⁰ of
15
rotation, supplied by the stepper motor. This was tested by inputting the desired range of motion into
the user interface and ensuring the catapult turned the desired degrees. It was desired to make over a
hundred launches. Our Ocean Server batteries have been used all day and still had plenty of power left
in them. We wanted to be able to launch a payload of up to 1 kilogram in weight. We were able to
launch several differently weighted and sized payloads. We wanted to consume less than 760 Watthours, which we did. We wanted to ensure we still had out of line of sight communication. This was
achieved, however, still needed some modification to work as planned. We wanted to be able to
retrieve 8 out of every 10 payloads launched. We were able to retrieve every payload launched. We
wanted to be able to pinpoint the payload landing. However, we did not work on acquiring the position
of the payload after it had landed. We wanted to be able to make sure this design could be used on the
moon. However, due to the low temperature of the moon, the dusty environment, and other unknown
conditions, we were not able to make our project moon-ready, though it was Earth-ready. Materials
that could work on the moon are just too expensive to implement in our project design at this point.
We wanted the base of the catapult to be 16 inches by 16 inches, with a height of 3 feet. We also
wanted the catapult to be less than 24 inches and 10 kilograms. All of these design constraints were
met.
Table 6 in Appendix A is our Design Failure Mode And Effect Analysis (DFMEA). It details each of
the possible methods of failure, their severity, how we can recover from the situation and the
recommended actions to limit the possibility/severity of the failure. Each of the subsystems have been
analyzed using this method.
Economic Analysis
We started with a budget of $6,000. Because of that, we decided to go with top quality
products. Based on an analysis of our expenses, we realized that we would finish the semester
right at our budget limit. However, we received news that our budget had increased by
approximately $4,000. With this, we decided to improve some of the components to the
control box, improve our spring selection and improve various aspects to the instrument
launcher design. Table 4 shows an approximated list of expenses broken down by subcategory.
Table 5 in Appendix A shows a complete breakdown of the team’s spending.
16
Table 4 - Proposed Budget
Project Category Sub Category
Materials
Motors
Mechanical
Launching Subassembly
Retrieval Subassembly
Manufacturing Services
Remote Control System
Onboard Control System
Electrical
Power Management System
Miscellaneous Components
Estimated Cost
$500
$200
$300
$300
$800
$1,200
$600
$2,500
$300
It is difficult to put a price on the time spent on the design. As a team, we spent a whole
academic year designing, building, improving, and rebuilding our catapult as well as
administrative paperwork, public relations, and other senior design tasks. Countless hours
were spent on this project. If seven members averaged 20 hours per week for 24 weeks (how
long we had to work on the project) for a total of 3360 man hours at $25.00 per hour (average
starting engineer’s salary), the project is worth $84,000. The hard cost of the project itself was
$8000. In all, the project cost was approximately (excluding travel) $92,000.
Compared to other NASA projects such as rovers and other mobile units, this project is
much more economical. Also, all of these products were purchased retail. NASA may be able
to purchase many of these products used in our design at a government discount price or may
simply be able to manufacture similar products. If NASA implemented this design, they would
save approximately $80,000 in labor costs. Also, because of the simplicity and repeatability of
this design, it can be used over and over and can also be mass manufactured which would cut
down on costs.
Conclusion and Recommendations
In summary, we have found that an acceptable method for launching a sensor array to collect
data and retrieve it is a simple design based on a catapult. The strong points of our design are its
17
simplicity and low power consumption. In addition, selecting an advanced control system allowed for
precise motor control as well as organized programming.
We feel that our design is an exceptional stepping stone in the process of developing an
effective stationary instrument launcher. That being said, we believe that there are numerous points
which can be improved. The first of which is the reloading mechanism. While ours is basically a ramp, a
more interactive device may be required should the sensor become irretrievable and need to be
untangled or detached and a new package loaded. Another major point to consider is the ratcheting
system. This will need to be improved in order to more efficiently transfer energy. Suggestions include
a ratchet with more teeth to improve the resolution of the range and an autonomous release system. In
addition to the aforementioned improvements, a braking clutch can be integrated with the spool
method of pulling back the arm to allow for a more efficient release of the arm. As of now, the control
system is a very powerful system and allows for quite a bit of modification. No recommendations for
improvement can be made at this point.
Even though the sensor is outside the scope of this project, two things to keep in mind are
optimizing the mass and spring and motor selection. The mass pulls back on the tether, which keeps the
reel from “bird nesting.” The more mass present, the less the line will bird nest, but too much mass will
restrict the maximum range of the catapult. A payload which is too light will not overcome the internal
drag of the reel and line. Because of the adaptability and scalability of the catapult, we can change
springs to accommodate different needs. Stronger springs, however, will need a stronger winching
motor.
If NASA decides to use this instrument launcher on the moon, we will be closer to reaching the
reality of lunar habitats. Our catapult leads the process in search of hydrogen and advancing lunar
research. With the advent of lunar habitats, scientists will be able to much more freely research
advances in spatial physics, lunar activity, missions to Mars and perhaps beyond. Our catapult forms the
foundation to achieving great and wondrous accomplishments.
18
target values
Power
X
X
Figure 7: House of Quality
19
16X16in
X
<10 kg
X
X
Package Self Deployment
Platform Height
Dusty Environment
Low Temperature Design
Pinpoint Payload Landing
Repeatable Retrieval
Maintain Communication
Max Power Consumption
Size of Payload
Mass of Payload
# of Data Points
Payload Rotational Range
Package Footprint
X
Package Mass
X
Package Height
Minimal Size
<24in
Autonomy
No human interaction
Platform Compatability
1m
Environmental Concerns
Dust Proof Storage
Communication
< 50K
Aim Controls
< 1 m error
Retrievable Payload
8 out of 10
Terrain Limitations
out of line of sight
Target Acquisition
< 760 Wh
X
<=6x6x6in
Payload Versitility
<=1kg
X
>100
Range
360 deg
customer
needs
Payload Launching Distance
tech specs
60m +/- 5m
Appendix A
X
X
X
X
X
X
X
X
X
X
Storage
Flight
Land at final
destination
Deployment /
Initialization
(Zeroing)
No
User targeting
(Range and
Bearing)
Target
Definition
Predefined Pattern
Autonomous?
Predefined Points
(Relative Bearing
and Range)
Yes
More Targets?
Payload loading
Yes
Retrieve Payload
Calculate Force /
Trajectory
Payload
Deployment
Payload Tracking
(Location)
Figure 8: Process Flowchart
20
Retrieve Data
No
!!! Self Destruct !!!
Figure 9: Sling Math Model
Figure 10: Sling Graphical Model Angular Velocity Vs. Radius of Cable
21
FOR Catapult
Velocity = 10m/s
mass (total) = 1.5kg
Powermoon(W)
Voltage
acceleration = 100m/s^2
Powerearth(W)
mW-hrsmoon
0.1
0.174
0.1811
0.004834
Force req. = 150 N
1
1.74
1.811
0.048337
pulse time = .1s
5
8.7
9.055
0.241686
F (moon) = 157.5N
8
13.92
14.488
0.386698
12.2
21.228
22.0942
0.589714
I = R/90 (see log book for defined values for the14.4
90)
25.056
26.0784
0.696056
F (earth) = 163N
Current (moon) = 1.75 A
Current (earth) = 1.811 A
Voltage = 5, 8, 12.2, 14.4 V
for reel motor on moon
for reel motor on earth
under max load
under max load
Time to
reel
60m in
(in
Torque
Power second …in
…in
(lbs in) F.L. amps (W)
s)
hours minutes
output
RPM
Watthrs
Time to
reel 10m
in (in
seconds)
…in hours Watt-hrs
10
100
2.7 1.047 2255.6 0.627
37.594 0.656
375.9398
0.104428
0.109356
30
100
5.2 3.142
751.9 0.209
12.531 0.656
125.3133
0.034809
0.109356
55
50
5.6 2.880
410.1 0.114
6.835 0.328
68.3527
0.018987
0.054678
90
36
5.8 3.393
250.6 0.070
4.177 0.236
41.77109
0.011603
0.039368
Figure 11: Catapult Power Spreadsheet
22
Variables/Constants
y 0  1.5m
g  9.807 m  s
Equations
2
v 0y v 0   v 0  cos ( )
  45deg
v 0x v 0   v 0  cos ( )
y  t v 0  g   y 0  v 0y v 0   t 
1
2
( g )  t
2
x t v 0   v 0x v 0   t
Trajectory on Moon
20


Height (Meters)
y  t 9
1 
  g
s
6  15
m


m


m
y  t 10
y  t 11
s
1 
  g
6 10
1 
  g 5
s
6 
0
0
8
16
24


32
x t 9
m
s
Trajectory on Earth
40
 
 
  x t 10
48
m
s
 
 
56
  x t 11
m
s
64
72
12
13.5
80


 
Distance (Meters)
5


Height (Meters)
y  t 9
m
s


m


m
y  t 10
y  t 11
 4

 g
s
s
3

 g


2
 g
1
0
0
1.5
3
4.5


x t 9
6
m
s
7.5
 
 
  x t 10
m
s
9
 
 
  x t 11
Distance (Meters)
Figure 12: Projectile Trajectory vs. Initial Velocity at 45 degrees
23
10.5
m
s


 
15
Figure 53: EML Force vs Turns vs AWG
Figure14: Force vs. Distance vs. Number of Turns
24
Table 5 (List of Expenses)
Date Order
Description
Quantity Price
Expenses
Running Total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------6000
39769 McMaster ball bearing for Sling Proto 1 1
10.21
5989.79
39772 Assorted Hardware for Emag Proto
multiple
1
44.01
5945.78
39773 3d Printing of the Sling
1
162.58
5783.2
39792 RCM4100 RabbitCore Development Kit 1
229
5554.2
39792 Laser 6 75 MHz Transmitter
1
142.98
5411.22
39829 Pelican 1600 Protector Case
1
165
5246.22
39840 BP-033R Backplane, Single 5.00mm 5 Position
8
Header
152
5094.22
39840 Combination Backplane Connector & Cable
4 24”59.84
5 Position Header
5034.38
39840 XP-08s Mini Battery Management Module
1
1195.7
3838.68
Line is used for above entry extra data sheet
0
3838.68
39849 Stepper motor
1
73
3765.68
39849 Stepper motor Control
1
99
3666.68
39849 Large Diameter turntable
1
31.59
3635.09
39849 LINKSYS WUSB54G USB 1.1/2.0 Wireless-G
1 Adapter
49.99- Retail
3585.1
39849 Kingston 2GB 240-Pin DDR2 SDRAM DDR2
1 667 (PC2
19.99
5300) Desktop Memory Model
3565.11
KVR667D2/2GR - Retail
39849 intec DS Lite Stylus Pens
2
9.98
3555.13
39849 Seagate Momentus 7200.3 ST9320421AS1320GB89.99
7200 RPM SATA 3.0Gb/s Notebook
3465.14
Hard Drive (Bare drive) - OEM
39849 Intel BOXD945GCLF2 Atom 330 Intel 945GC
1 Mini
83.99
ITX Motherboard/CPU Combo
3381.15
- Retail
39849 SAMSUNG Gray & Black USB 2.0 Slim External
1
8X
74.69
DVD Drive USB-Powered Model
3306.46
SE-S084B - Retail
39849 Logitech V10 2.0 USB Notebook Speakers
1 - Retail
99.99
3206.47
39850 15" Touch Screen Monitor
1
499.99
2706.48
39855 Cabela's All Pro Casting Reel
1
38.98
2667.5
39855 30 lb Cabela's ProLine® Original Line – Natural
1
Clear
5.99
2661.51
39855 Black & White USB 2.0
1
36.99
2624.52
39855 Freewheel 13 tooth
1
24.99
2599.53
39856 1/8" Aluminum 6061-T6 Sheet 36x48" 1
107.14
2492.39
39856 3/2"x3/16" 6061-T6 Aluminum tubing 84"
2 long 67.36
2425.03
39856 3/4" 6061-T6 Aluminum Round, Cold Finish
1 12"40.61
long
2384.42
39856 Angle Bracket
8
4.72
2379.7
39856 3/4" shaft mount
1
56.26
2323.44
39856 Metric Socket Screw M4 P.7 by 10 mm long
1 package
6.85 of 100
2316.59
39861 .19 Lb/in K Tension Spring
6
37.38
2279.21
39861 .38 lb/in K Tension Spring
4
14.64
2264.57
39861 Plain Bearing (bushing)
2
8.9
2255.67
39861 Graphite Dry Lube
6
19.74
2235.93
39861 Angle Brace 90 deg
8
7.52
2228.41
39863 Polypropylene Base Furniture Set
4
33.16
2195.25
39863 2x12x.75" Aluminum Strip
1
13.18
2182.07
39863 Polyethylene-Cushioned Base Furniture4Set 28.56
2153.51
39863 .125x.125" Brass Key Stock
2
2.48
2151.03
39867 320 W Power Supply 18 V
1
214.25
1936.78
39867 DC in power cable with ring tongue
4
20.68
1916.1
39867 Mini Fir Connectors 2 Pin
20
24
1892.1
39867 Mini Fir Connectors 4 Pin
20
30
1862.1
39867 Mini Fir Connectors 6 Pin
15
26.25
1835.85
39867 Mini Fir Connectors 8 Pin
20
39
1796.85
39867 Mini Fir Connectors 10 Pin
5
14.75
1782.1
39867 Mini Fir Connectors 12 Pin
2
7
1775.1
39868 20 Ft Primary Wire 11 Violet
1
6.5
1768.6
39868 30 Ft Primary Wire 3 Green
1
6.5
1762.1
39868 40 Ft Primary Wire 2 Black
1
6.5
1755.6
39868 40 Ft Primary Wire 4 Red
1
6.5
1749.1
39868 40 Ft Primary Wire 5 Yellow
1
6.5
1742.6
39868 Shipping for all Action Electronics
1
13.42
1729.18
39868 Facilities Fees on Monitor Mount and Shearing
1
Metal
133
1596.18
39869 Fully Keyed 1045 Steel Drive Shaft 1/2" OD,
1 1/8"
18.21
Keyway 1' long
1577.97
39869 Bronze Flange Bearing 1/2" ID
4
5.08
1572.89
39869 Steel external Retaining Ring for 1/2" diameter
1
2.17
shafts 10 pack
1570.72
39869 Steel external Retaining ring for 1/4" diameter
1
8.09
shafts 10 pack
1562.63
39869 Zinc plated steel threaded Rod 1/4"-20 thread,
1
1'0.8
length
1561.83
39869 Mounted Pully 1/4" diameter rope 11/16"
1 OD on
7.11
Pully
1554.72
39869 Alumminum Bar 1" x 2" x12"
1
54.2
1500.52
39869 Sleave Bearing 1/4"
5
3.1
1497.42
39869 T3257S-12V 12Vdc, 0.75” stroke, push solenoid
2
103.32
1394.1
39897 Annodizing multiple catapult parts
1
165
1229.1
39900 Rapid Prototype of battery case and reel4 mount
455.08
774.02
39903 3mm Keyway Broach style A
1
42.06
731.96
39903 4mm Keyway Broach style B1
1
49.25
682.71
39903 Keyway Bushing Collared 8mm A
1
10.47
672.24
39903 Keyway Bushing Collared 10mm A
1
10.47
661.77
39903 Keyway Bushing Collared 12mm A
1
10.47
651.3
39903 Keyway Bushing Collared 12mm B1
1
10.36
640.94
39903 Plain Steel Angle Brackets 6x8"
4
53.6
587.34
39903 ¼-20 2” Screws
1
7.13
580.21
39903 5’ of 2” adhesive backed Velcro strip
1
15.01
565.2
39905 Omnex Wireless Kill Switch
1
1073
-507.8
25
26
27