Final project design presentation for ENES100, Introduction to Engineering Design.

4. Autonomous navigation
Engineering principles
Competition

5.  Propulsion System
 Original ducting design proved to be inefficient
 Weight of turning system caused imbalance
 Ridges inside ducting and distance between nozzle and fan caused loss
of air flow and hence propulsion force
 Power System
 As power requirements changed, regulator requirements changed, leading
to many changes in voltage regulation
 Faulty parts led to circuit failures and constant redesigning
 Insufficient heat sink (See later slide)

7.  Structure and Levitation System
 Initially small design led to instability and difficulty in balancing
 Fan failures led to restructuring of craft and emergency decisions
 Skirt design allowed large amounts of air to escape and low control of shape
 Programming and Sensors
 Conflicting commands led to an oscillating fan action
 Difficulty in managing drift and fishtailing
 Difficulty in reacting to curve in track

8.  Used 1.5in Foamulur InsulPink Furring Lap Foam for Main Body and
Support Structure
 Used Silicone Impregnated Ripstop Nylon for Skirt
 Design
 A half-inch thick skirt support structure attached underneath for skirt rigidity while
still allowing for soft skirt properties and inflation
 Skirt attached to top of craft and bottom of support structure using double-sided
foam tape
 Adhesives and Attachment Methods
 Adhesive caulk on main structure
 3/16 in metal bar and polycarbonate structures for servo, line sensor, and propulsion
 Screws to attach threaded or drilled components

10. Air Flows Into Body
Air Flows Through
Opening to Inflate Skirt
Air Flows Through
Bottom to Levitate Craft

11.  San Ace 80
 Counter-Rotational
 S-speed model
 80x80x80mm
 350g
 12V, 4.8A

13.  The plotted point (1.91 m^3/min,
86.16 Pa) falls under the curve
 Decreased the fan’s flow rate for
desired hover height
 Central hole smaller than fan’s
output radius
 Tape placed on input side of fan

14. Used half of a SanAce 80 Counter-
Rotating fan
 12v, 0.7 Amps
 About 70CFM
 About 0.26 Newtons of thrust
 Acceleration: 0.145 meters per second
per second
 Turning Rate: 0.454 radians per second
Turned by LEGO servomotor
 Fan attached to a Lexan®™ plate,
supported by steel beams
 Servo placed on a Lexan®™ and steel
support structure
 Allows direct flow, applying immediate
and direct thrust

15. Used a 14.8v Lithium-Manganese-Nickel
battery
Fans in parallel draw 12v and 5.5 Amps
Voltage regulated to 12v using a
LT1083CP 12v, 7.5A Fixed Voltage
Regulator
Used capacitors to maintain signal
stability
Master and secondary switch control
Components soldered to breadboard for
a compact and neat design
Bread board attached to aluminum plate
with insulated standoffs
Battery leads connected with crimp-on
tongue connectors attached to a barrier
block

17.  PD=(I)(ΔV)=(5.5A)(16.6v-12v)=25.3W
 TA=25 C
 TJ=TA+P*ΘJA
= 25 C + (25.3W)(45 C/W)
=25 C+1138.5 C
=1163.5 C
 1163.5 C>125 C
 Hence, the regulator required a heat sink to maintain the device’s
temperature below the maximum temperature.
 Standard Radio Shack heat sink was insufficient and overheated easily

18. Used a custom designed heatsink
manufactured out of aluminum channel
 Increases surface area
 Uses aluminum instead of duralumin
 Thermal conductivity of aluminum: 250 W/mK
 Thermal conductivity of duralumin: 164 W/mK
 Allows high contact without the aluminum
oxide coating
Used silicone heat sink compound to allow a
good thermal connection between the output
plate of the regulator and the heat sink

19. • Used NXT Microcontroller to execute
programmed routines
• Used two sensors to compliment each
other on different portions of the track
• Mindsensors LineLeader
• Provides feedback on position
relative to line
• LEGO Gyroscopic Sensor
• Provides feedback when line sensor
recognizes the friction obstacle,
which has no line to follow
• Provides a reading of the
hovercraft’s angular velocity, which
is then calculated to provide a
heading reading

20. Initialize Variables Turn fan a
-Limits of black and Sensor Yes constant times
Read line leader
white Read the number of
left to right
-gyroscope constants White? sensor degrees to
-recurring values the right
No
Turn fan a
Sensor Yes constant times
Read line leader
Read the number of
right to left
White? sensor degrees to
the left
No
Yes Read
Turn fan to Black
zero degrees Both
Times?
Get
No Calculate
Reading Calculate Turn fan
angle
from fan angle to angle
offset
Gyro

21. Part Manufacturer Part Number Mass (g) Price/Unit Quantity Total Price
San Ace 80 Levitation Fan San Ace 9CR0612P0S03 350 $48.00 1 $48.00
Fan Guard Mesh --- --- 10 $0.50 3 $1.50
San Ace 80 Propulsion Fan San Ace --- 175 $48.00 1 $48.00
Acrylic Sheet for Propulsion LEXAN 31-GE-XL-1 7.5 $4.47 1 $4.47
NXT Intelligent Brick Lego 9841 320 $50.00 1 $50.00
Gyroscopic Sensor Lego MS1044 15 $54.99 1 $54.99
Line Sensor Array for NXT Mindsensors --- 15 $44.95 1 $44.95
Servo Motor Lego 9842 60 $19.00 1 $19.00
14.5" NXT Connector Cables Lego 8529 45 $1.50 3 $4.50
1.3 oz. Silicone Impregnated Ripstop
Nylon Seattle Fabrics --- 35 $11.50 0.5 $5.75
Foamulur InsulPink Furring Lap Foam Owens Corning 271038 85 $12.44 0.5 $6.22
LiMnNi Battery Battery Space 4210 420 $59.95 1 $59.95
Velcro Velcro 90199 4.5 $3.47 1 $3.47
Caulk Polyseamseal 1152297 5 $2.99 1 $2.99
Metal Bar for Propulsion Home Depot 48880 15 $3.53 1 $3.53
Skirt Double Sided Foam Tape Scotch --- 10 $2.97 1 $2.97
Screws and Nuts Home Depot --- 25 $0.98 2 $1.96
Aluminum Sheet Metal --- --- 25 $0.74 1 $0.74
Aluminum C Channel Lowes --- 50 $0.72 1 $0.72
10µF Capacitor Radio Shack 272-1013 10 $1.19 2 $2.38
20A Switch Radio Shack 275-0010 7.5 $2.99 1 $2.99
25A Switch Radio Shack 275-708 7.5 $2.99 1 $2.99
Heat Sink Mounting Kit Radio Shack 276-1373 20 $1.99 1 $1.99
7.5A 12v Voltage Regulator Arrow Electronics LT1083CP-12#PBF 7.5 $8.83 1 $8.83
Tongue Clips Radio Shack 64-3128 5.5 1.99 1 $1.99
Barrier Strip Radio Shack 274-656 15 2.09 1 $2.09
22AWG Wire Radio Shack 278-1218 8 6.99 0.03 $0.21
PC Breadboard Radio Shack 276-168 22.5 2.99 1 $2.99
10mm Insulated Standoffs Radio Shack 276-1381 15 2.99 1 $2.99
Heat Sink Compound Radio Shack 276-1372 10 2.99 1 $2.99
Total 1800.5 $396.15

23. • Product Specifications Met
• Only the in-house fabricated skirt touched the ground
• At 44 minutes, the craft could levitate for over 10 minutes on one battery charge
• Utilized an approved microcontroller to maintain autonomy
• Mesh fan guards used to pass safety requirements
• Total as-built replacement cost under $400
• Product Specifications Not Met
• Navigate the track in under 10 minutes without touching a side wall
• Followed Milestone guideline, maintaining a structured development
process
• Passed all Milestones beyond the final qualification milestone

24. • Component Manufacturing Skills
• Lab Safety
• Engineering Design Process
• Teamwork and Problem Resolution
• Critical Thinking and Design
Development
• Improving Off Success and Developing
from Failure
• Programming and Autonomous
Systems
• Physics
• Electronics
• Fluid Dynamics
• Dynamics
• Thermodynamics

25.  Friction effects and creating a large distance between the fan and the
output drastically decreases the air flow acting on the air
 Improvement Made: Had the fan directly exposed to the air and directly driven
 Readily available and popular products are usually not the best.
 Cases: Two SanAce fans burning out or decreasing in performance, Radio Shack
components breaking under their specified requirements
 Improvements Made
 Used portions of the SanAce fans that still functioned
 Ordered higher quality circuitry components
 Improvements That Would Be Made/Recommendations to Future Teams
 Avoid SanAce and Radio Shack products. Their price is inversely proportional to quality.

26.  The smaller the craft, the less stable it is. Finding a safe middle ground
that provides stability and efficiency is key.
 Improvement Made: Increased size of craft to keep a relatively small size and low
weight, yet maintained more stability than previous smaller designs
 Having only one fan for propulsion can work for turning, but leads
to fishtailing and drifting
 Improvements That Would Be Made/Recommendations to Future Teams
 Make turning controls symmetric to maintain stability when turning

27.  The NXT, servomotor, and half of the gyroscopic sensor models were
originally created by the Carnegie Mellon Robotics Academy.
 Any additional models, graphics and diagrams were originally created by
Team Grease Lightning.