Mission Statement and Objectives
Design Requirements
Functional
•
Log radiation and corresponding altitude for duration of flight
(up to 90,000 feet and back)
•
Store data on non-volatile memory
•
Provide power for duration of flight plus one hour set up and
one hour for recovery (4 hours minimum)
•
Indicate the unit is powered on
•
Indicate system is running properly
•
Ensure system is both water-resistant and buoyant
•
Provide internal fire resistance
•
Provide internal temperature regulation
•
Ensure system will operate within temperature range and
withstand forces of launch, ascent, balloon breaking, descent,
and landing
•
Ensure system can attach to research computer payload
•
Ensure combined system can attach to Borealis balloon
Performance
•
Log radiation and altitude data each second
•
Provide 5 watts per hour over 4 hour flight
•
Provide sound and/or light to indicate power is on
•
Provide sound and/or light to indicate the system is operating
properly
•
•
Ensure water cannot leak into system and payload floats
Enable system to shut down if internal temperature exceeds
100 C
•
Ensure system can withstand vertical force of 10Gs and
horizontal force of 5Gs (according to HASP requirements)
•
Ensure payload temperature stays within and will operate
between -60 and 60C (external) and between -20 and 40C
(internal)
•
Ensure pressure sensor can withstand 0-90kPa
Physical
•
Ensure system does not exceed maximum dimensions: 5.5” by
5.5” by 5.5”
•
Ensure system does not exceed maximum mass: 6 lbs
Reliability
•
Ensure system can launch twice and withstand internal tests:
• Drop test
• Bench-top burn test
• Cold room test
• Water resistance test
• Pressure test
•
Recover all components and ensure internal components are
not damaged
Design Alternatives
Arduino Uno
Raspberry Pi
Freescale
Data Logger
25 + 20 + 13 = $58
25 + 13 = $38
13 + 13 + 20 = $46
45 + 10 = $55
Cost
System Shield SD Card Total
Mass
System Shield SD Card Total
30 + 22 + 2 = 54g
System SD Card Total
31 + 2 = 33g
System SD Card Total
System SD Card Shield Total
15 + 2 + 22 = 39g
System SD Card Shield Total
System x2 Micro SD
13 +
Total
1 = 14g
System x2 Micro SD
Total
Power
1.15 Watt
1.50 Watts
.25 Watts
.05 Watts
Dimensions
2.95” x 2.09”
3.37” x 2.20”
3.2” x 2.1”
0.6” x 0.75” and
0.90” x 0.70”
Input Voltage
7 – 12V
5V
5V
3.3 – 12V
Non-Volatile
Storage
Separate SD Shield
Built-in SD Shield
Separate SD Shield
Built-in Micro SD Shield
and Flash Storage
Sensor
Interface
UART to Geiger Counter
Analog to Pressure Sensor
UART to Geiger Counter
I2C to Pressure Sensor
UART to Geiger Counter
Analog to Pressure Sensor
UART to Geiger Counter
Analog to Pressure Sensor
Design Comparison
Final Decisions and Budget
Raspberry Pi:
+
SD Card:
$25
Total:
$38
$13
Computer Subsystem Tests
Test 1- Connect Geiger counter to development board
- Read and interpret data
Test 2- Connect pressure sensor to development board
- Read and interpret data while in pressure chamber
Test 3- Write to SD card
Program Design
Radiation Sensors
Sparkfun Geiger Counter SEN11345
Mighty Ohm Geiger Counter
Kit
Price
$149.95
$99.95
Voltage Supply
5V (USB)
3V (two AA batteries)
Temp Range
-40 – 75C
-60 – 70C
Current
30mA
10mA
Size
4.15” x 1.75” x 1”
4.75” x 2.75” x 1”
Weight
~117g
~200g
Ratings
Additional
Acrylic conformal
coating to protect
both Geiger
counter and the
rest of the circuit
MG Chemicals
419C-340G
MG Chemicals 419C-55ML
Price
$17.96
$10.95
Type
Aerosol
Liquid
Size
12oz
2oz
Max Temp
40C
40C
Pressure/Altitude Sensor
LPS331AP
Pressure/Altitude
Sensor
HSCDLNN400MGSA5
SSCMRNN100PG4A5
Price
$11.59
$35.45
$32.54
Temp Range
-45 – 80C
-20 – 85C
-40 – 85C
V In
2.5V
5V
5V
Pressure Range
26 – 126kPa
0 – 40kPa
0 – 689kPa
Analog vs Digital
Output
Digital
Digital
Digital
Ratings
Load
DC/DC Converter
XP Power Recom Power
Rohm
Rohm
Semiconductor
Semiconductor
w/Heat Sink
Fairchild
Semiconductor
Price
$10.50
$7.49
$6.25
$6.25
$0.67
V out
5V
5V
5V
5V
5V
I out
1A
1A
500mA
800mA
1A
V in
6.5 – 18V
6.5 – 18V
6 – 14V
6 – 14V
5 – 18V
Power
5W
5W
2.5W
4W
5W
Temperature
Range
-40 – 85C
-40 – 85C
-30 – 85C
-30 – 85C
-40 – 85C
Linear vs
Switching
Switching
Switching
Switching
Switching
Linear
Efficiency
88 – 93%
89 – 94%
88% Nominal
88% Nominal
NA
External
Components
Capacitor
Optional Blocking
Diode
NA
Heat Sink
NA
Ratings
Power Source
Energizer
Advanced Lithium
Energizer
Rechargeable
Energizer
Industrial
Duracell Ultra
Lithium
Price
$1.75
$1.89
$0.70
$1.50
Temp Range
-40 – 60C
-18 – 55C
-18 – 55C
-20 – 60C
V Out
1.5V
1.5V
1.5V
1.5V
Weight
14.5g
23.0g
23.0g
16.2g
Configuration
5 Batteries
6 Batteries
8 Batteries
+7.5V
+9V
+12V
V Out DC/DC
5V
5V
5V
P Out
2.5W
2.5W
2.5W
I Out
500mA
500mA
500mA
Efficiency
90%
90%
90%
P In
2.8W
2.8W
2.8W
V In
7.5V
9V
12V
I In
370mA
310mA
230mA
Configuration
Energizer
Advanced Lithium
Energizer
Rechargeable
Energizer
Industrial
Duracell
Ultra Lithium
Time
Cost
Mass
Time
Cost
Mass
Time
Cost
Mass
Time
Cost
Mass
+7.5V
8hrs
$8.75
72.5g
4.3hrs
$9.45
115g
4.3hrs
$3.50
115g
7hrs
$7.50
81g
+9V
10hrs
$10.50
87g
5.65hrs
$11.34
138g
5.7hrs
$4.20
138g
10hrs
$9.90
97.2g
+12V
15hrs
$14.00
116g
8.7hrs
$15.12
184g
8.7hrs
$5.60
184g
15hrs
$12.00
129.6g
Ratings
Electrical Subsystem Tests
Burn in test
• Breadboard the design and power the circuit, to see how
long the batteries last
DC/DC converter test
• Test to make sure the DC/DC converter is outputting the
right value
Cold test
• Place the fully manufactured circuit in the enclosure and
test the enclosure in the cold lab
Final Decisions and Budget
Geiger Counter:
+
Pressure Sensor:
+
DC/DC Converter:
+
Batteries:
+
Battery Boxes:
+
PC Boards:
+
Misc:
$150
Total:
$307
$33
$7
$80
$5
$12
$20
Structural Alternatives
-Hard Foam
-Gorilla Tape
1.
-Packing Tape
-Hard Foam
-Gorilla Tape
2.
-Packing Tape
-Fiberglass
-Thinsulate
3.
-Fiberglass
4.
-Vinyl
Preliminary Testing- Prototype 1
Enclosure
Specifications Pass?
Attachment
Impact Forces/Environmental Protection
Specifications
Pass?
Specifications
Pass?
5.5" cube
yes
Attach to Research
computer payload*
yes
Meets HASP requirements for Gforces*
yes
Fits Electronics
yes
Attach to BOREALIS
yes
Buoyant &Water Resistant
yes
0.1394 kg
yes
Electronics are secure
yes
Materials resist fire*
yes
Meets Internal Temperature
Range*
yes
*Preliminary testing results to follow
-Hard Foam
-Gorilla Tape
-Packing Tape
-Fiberglass
Attachment Method- Prototype 1
•Bottom of our payload will be bolted to top of
research computer payload
•Research computer payload will attach to BOREALIS
Balloon
-Prototype Lid
-4 Screws
-Prototype Box
-Existing Research
Payload
Drop Test- Prototype 1
HASP
Requirements
Avg. Descent Rate
BOREALIS
Drop Test Results
Impact Velocity (m/s)
3.13
7.62
14.9
Height (m)
0.546
3.43
11.3
Deceleration at Impact
(m/s^2)
98.01
2,903
4,040
G-Force (G’s)
10
296
411.94
Internal Testing- Prototype 1
Burn test- tested material resistance to fire
•Shredded Polyurethane Foam
Burns only when flame is held on foam
•Thinsulate
Melts when flame is held on it but does
not catch fire
•Packing tape
Melts when flame is held on it but does
not catch fire
•Polystyrene Foam Board
Melts when flame is held on it but does
not catch fire
•Fiberglass
Melts when flame is held on it but does
not catch on fire
Cold Test- Prototype 1
Test 1: No Thinsulate Bag,
Shredded Packing Foam
Test 2: Thinsulate Bag,
Shredded Packing Foam
Thermocouple on
circuit board
Test 3: Control Box: No
Thinsulate Bag, No Shredded
Packing Foam
Thermocouple on
battery pack
Cold Room Test- Prototype 1
50
40
30
Temperature (⁰C)
20
Environmental Temperature
10
Test 1 Battery Thermocouple
Test 2 Battery Thermocouple
0
Test 3 Battery Thermocouple
Test 1 Thermocouple on Circuit Board
-10
Test 2 Thermocouple on Circuit Board
Test 3 Thermocouple on Circuit Board
-20
-30
-40
-50
0
10
20
30
Time (minutes)
40
50
60
Budget
Building Materials:
$40
packing tape, fiberglass kit,
gorilla tape, gorilla glue, etc.
+
Shredded Foam:
+
Polystyrene ½” Board:
+
Thinsulate:
+
TI Sensor Tag:
Total:
$2
$2
$15
$25
$84
Overall Budget
CS Materials
+
EE Materials
+
ME Materials
$38
Total:
$429
$307
$84
$171 under budget!!!
Computer Subsystem Anticipated Schedule
Week 1:
June 17
= Event
= Milestone
M
T
W R
Week 2:
June 24
F
M
T
W R
Week 3:
July 1
F
M
T
W R
Week 4:
July 8
F
M
T
W R
Week 5:
July 15
F
M
T
W R
Week 6:
July 22
F
M
T
W R
Preliminary Design
Review
Order Components
Program Geiger
Counter Interface
Program Pressure
Sensor Interface
Program SD Card
Interface
Critical Design
Review
Full Program
Design
Test Support
Software
Full System Test
Launch #1
Launch #2 (if
necessary)
Documentation
Window
Window
F
Electrical Subsystem Anticipated Schedule
Week 1:
June 17
= Event
= Milestone
M
T
W R
Week 2:
June 24
F
M
T
W R
Week 3:
July 1
F
M
T
W R
Week 4:
July 8
F
M
T
W R
Week 5:
July 15
F
M
T
W R
Week 6:
July 22
F
M
T
W R
Preliminary Design
Review
Order Components
Circuit Design
Bread Board Circuit
Testing
Critical Design
Review
Manufacturing
Perform Additional
Testing
Full System Test
Launch #1
Launch #2 (if
necessary)
Documentation
Window
Window
F
Mechanical Subsystem Anticipated Schedule
Week 1:
June 17
= Event
= Milestone
M
T
W R
Week 2:
June 24
F
M
T
W R
Week 3:
July 1
F
M
T
W R
Week 4:
July 8
F
M
T
W R
Week 5:
July 15
F
M
T
W R
Week 6:
July 22
F
M
T
W R
Preliminary Design
Review
Test All
Prototypes
Choose Optimal
Prototype
Simulation Testing
Critical Design
Review
Manufacturing
Perform Additional
Testing
Full System Test
Launch #1
Launch #2 (if
necessary)
Documentation
Window
Window
F
Thank you!