Aloft Stratospheric Testbed for Experimental Research on Infrasonic Activity
Courtney Ballard | Emily Daugherty | Connor Dullea | Kyle Garner | Martin Heaney | Ian Thom | Michael Von Hendy |
Kerry Wahl | Emma Young
Topic
Presenter
Michael
Project Overview
Kerry
Schedule
Manufacturing
•
Electrical
Courtney
•
Software
Michael
•
Mechanical
Connor
Kerry
Budget
Background
Design
Overview
Microphone
Thermal
Mechanical
Risks
V&V
Project
Management
2
Background
Schedule
Electronics
Software
Mechanical
Budget
3
Develop a protoflight* high-altitude balloon payload capable
of measuring infrasonic events of frequencies between 0.1
and 20 Hz with a minimum amplitude of 0.1 Pa.
Functional Requirements:
Requirement
Designation
Description
FR.1
ASTERIA shall measure and record simulated
infrasonic sources between 0.1 and 20 Hz, with a
minimum wave amplitude of 0.1 Pa.
FR.2
FR.3
ASTERIA shall be capable of operating on a balloon
that travels to an altitude of 18 to 21 km.
ASTERIA shall operate autonomously for a minimum
of 24 hours, the duration of the mission flight.
*Protoflight: Hardware that is designed to flight standards, but may not
incorporate
all the necessary materials or testing required to be flightProject
Design
Background
Microphone
Thermal
Mechanical
Risks
V&V
Overview
Management
certified
4
Infrasound: Sound waves below the
threshold of human hearing (0.1-20 Hz)
•
Generated by severe weather,
earthquakes, volcanoes, meteors
Current monitoring network is only
capable of detecting ~30% of 0.1-kiloton
events due to wind noise [Pinchon 2010]
Desire to increase detection of events
•
Important for design of re-entering
spacecraft, verification of atmospheric
models
Bolides** produce a majority of their
infrasound at altitudes of 20-30 km.
[Pinchon, 2010]
Microphone
STRATOSPHERE
PRESSURE WAVES (INFRASOUND)
ASTERIA
BOLIDE
GROUND STATIONS
(EXISTING)
Background
Spatial Filter
**Bolides:
Meteors that
explodeMechanical
in the Earth’s
Microphone
Thermal
Risksatmosphere
V&V
Design
Overview
Project
Management
5
VOLTAGE
Current Project: Protoflight Ready Sensor & Support Systems
Patm , Tatm
TIME
Pressure
Data Out
P, T
Microphone
Infrasound
Source
Background
Simulated Infrasound
Waves
Design
(0.1-20Hz)
Microphone
Thermal
Overview
Wind
Barrier
Support Systems:
Power, Thermal,
Structural, Data
ASTERIA
Mechanical
Risks
V&V
Project
Management
Infrasound Pressure
Wave Propagation
(0.1-20 Hz)
ASTERIA
Wind
Barrier (X5)
Microphone System (x5)
Reduced Wind
Noise Signal
Differential
Pressure
Transducer
(Active)
Temperature
Sensor
Amplification +
Low-Pass Filter
Pressure Signals
Differential
Pressure
Transducer
(Reference)
A/D Converter
Conditioned
Signals
Amplification +
Low-Pass Filter
A/D Converter
Digital Pressure
Signals
7V Regulator
3.3V
Regulator
Connector
11.1V
(2200mAh)
Key:
Physical Connection
Digital Signal
Analog Signal
Power
Microphone Board
Control Board
Batteries
PIC Controller
Board
Connector
(x5)
Digital Signals
7.4V
(20.8Ah)
5V
Regulator
±5V
DC/DC
Converter
3.3V
Regulator
Digital Data
PIC
Controller
SD
Storage
USART
USB-USART
Conversion
USB In/Out
Project Element
Description
Microphone Design & Data
Collection
0.01 Pa changes (0.8 μV changes) require
extensive signal conditioning and interfacing.
Stratospheric Survivability of
Payload
Must maintain components within -10 to 45°C in
ambient temperatures of -55 and 30°C.
Infrasound Generation & Test
Equipment
NOAA piston bellows set-up has successfully
generated infrasound.
Data Storage Survivability
Max. loads expected to be well below data
storage system specifications (to be verified by
drop test).
Mass Budget
Current mass (8 kg) is well below requirement
(20 kg).
Power Budget
Batteries provide a power margin of ~25%.
Background
Schedule
Electronics
Software
Mechanical
Budget
8
Background
Schedule
Electronics
Software
Mechanical
Budget
9
Changes:
• PCB Assembly and Structure manufacturing slipped 2 weeks – consumed 2 weeks of margin
• Addition of Pendulation Simulation to Software
• At least 2.5 weeks of margin remaining on all tasks
TSR
MSR
SFR
MP PCB Rev. 2
Electronics
Electronics
Testing
PCBs Rev. 1
New Margin
MC PCB Rev. 2
Software
Data Storage Routine
Circuit Debug Testing
Pendulation Model
Old: Feb. 15
New: Feb. 25
Pre-flight
Diagnostics
Mechanical
Old: March 10
New: March 19
Old: March 1
New: March 9
Schedule
Electronics
Old Path:
Margin
Critical
(At1&2
least
2.5
• PCB Rev
Development
(~4
Weeks)
• Data Storage
Routine Development
Weeks)
• Core/Outer Structure Manufacturing
Payload Integration
Structure Manufacturing
Background
Old: Feb. 15
New: March 9
Software
Mechanical
Budget
10
Background
Schedule
Electronics
Software
Mechanical
Budget
11
Data Collection
• Dual transducer system with acceleration
and temperature compensation
Data Handling
• PIC18 Microcontroller and MicroSD using
SPI communications
Power Systems
• Dual Li-Ion batteries at 7.4V and 11.1V
FR.1 Measure and record infrasound
CPE.1 Microphone Design/Data Collection
LOS.1 Frequency and Resolution
LOS.3 Sampling Rate
LOS = Level of Success
Design Changes from CDR
• Selected different voltage
regulator due to unavailability of
7V regulator
• Switched to PIC18F8722
Microcontroller to handle 3.3V
power supply
Background
Schedule
Electronics
Software
Mechanical
Budget
12
Finished
Control PCB Rev. 1
PCB Rev 1.
Completion
Feb. 6th
Microphone PCB Rev. 1
Set-backs and Solutions:
• Board development required
additional time due to last
minute problems discovered
• Rev.1 Board lacked
programming header,
intermediary revision
ordered
Control PCB Rev. 2
PCB Rev 2.
Completion
March 9th
Microphone PCB Rev. 2
0
5
10
Complete
15
20
Hours
Remaining
25
30
All estimates based on
a 10hr work week per
student
Margin
Summary: All electronics are on schedule
Background
Schedule
Electronics
Software
Mechanical
Budget
13
Future Testing
• Acceleration and temperature sensitivity testing/calibration – Feb. 10th
• Flight-prototype piston bellows test – Feb. 9th
Task
%
Start Date
Completion
Deadline
Status
Rev 1. PCB
Assembly
75%
1/23
2/6
On Schedule
Rev. 1 PCB
Debug
30%
1/25
2/6
On Schedule
Rev. 2 PCB
Layout
25%
1/25
2/12
On Schedule
Rev. 2 PCB
Assembly
0%
2/16
3/9
Not Started
Background
Schedule
Electronics
Software
Mechanical
Budget
14
Background
Schedule
Electronics
Software
Mechanical
Budget
15
Status from CDR:
SPI Communications Protocol
•
Acquires measurements from sensors
• Send/Receive Byte from peripheral device
• Provides 46% timing margin at 100Hz sample rate. 5.685 ms per
operation
SD Card File System
•Provides pre-written C-like functions for archiving data on SD card
•Functionality: Create file, open file, write value to file, etc.
•Meets customer’s data plug and play requirement
USB to USART
•Provides method to directly communicate with laptop for pre-flight
FR.1 Measure/record
CPE.1 Microphone
LOS.2 Minimum
infrasound (0.1-20 Hz,
Design/Data
sampling frequency of
0.1-100 Pa)
Collection
100 Hz
LOS = Level of Success
Background
Schedule
Electronics
Software
Mechanical
Budget
16
Main Loop
Low Priority Interrupts
High Priority Interrupts
Current Buffer?
Data Acquisition
Interrupt
Overflow Prevention
Interrupt
2
1
Buffer Full?
No
Yes
Write Buffer to SD
Clear Buffer
Switch Buffer
Background
Schedule
Enable SPI
Interrupt
Increment
Overflow
SPI Acquisition
Interrupt
Check Sensor Case
Temp.
Buffer Full
Other Buffer Empty?
No
Yes
Error
Change
Buffer
Pressure
Send Data to Buffer
Electronics
Software
Mechanical
Budget
17
Start: 2/15
End: 3/29
Post-processing Code
All estimates based
on a 10hr work
week per student
Start: 2/15
End: 3/29
Pre-flight Code
Main Code Complete by:
Feb. 25th
Main Code
0
10
20
Complete
30
40
Hours
Remaining
50
60
Margin
Summary: All software is on schedule.
Background
Schedule
Electronics
Software
Mechanical
Budget
18
Remaining Functions
• Pre-flight diagnostics: 2/27
• Run main data collection loop on ground. Output data to laptop.
• Post-processing software 3/9
• Convert binary voltage/temperature measurements into calibrated pressure
values
Future Testing
• Peripheral operating test – 2/6
• Pre-flight diagnostics test – 2/28
Percent
Completion
Start Date
Deadline
Status
20%
1/26
2/25
On Schedule
Pre-flight Diagnostics
0%
2/15
2/27
Not Started
Post-Processing
0%
2/15
3/9
Not Started
95%
1/5
2/13
On Schedule
Electronics
Software
Task
Data Collection
Pendulation Model
Background
Schedule
Mechanical
Budget
19
Background
Schedule
Electronics
Software
Mechanical
Budget
20
External Structure Changes:
-Foam barrier inside tubing instead of
on the exterior to simplify assembly
24
”
24”
Internal Structure Changes:
-Casing around batteries for mounting
and protection
-Reduced board sizes for both the
control board and microphone boards
to provide space for battery casing
7.75”
Background
Schedule
Electronics
Software
Mechanical
7.75”
Budget
21
Three-arm Cap Plate
Hoist Rings
6”
Battery Casing
Internal
Support
Arm
Nylon Tubing
24”
7.75”
Polystyrene
Insulation
L-bracket
Internal
Hexagonal cap
External Support Arm
Background
Schedule
Electronics
Software
Mechanical
Budget
22
L-Brackets (x24)
Bandsaw/Mill – due Feb. 11th
Internal Support Arm (x3)
Knee Mill – due Feb. 6th
Internal Hexagonal Cap (x2)
All estimates based on
a 10hr work week per
student
CNC Mill – due Feb. 6th
Support Arm (x2)
Knee Mill – due Feb. 18th
Three-Arm Cap Plate (x2)
CNC Mill – due Feb. 18th
CNC Mill – due Feb. 18th
Polystyrene Insulation (x12)
0
5
Complete
10
15
Hours
Remaining
20
25
Margin
Summary: Structure manufacturing is on schedule
Background
Schedule
Electronics
Software
Mechanical
Budget
23
Future Testing
• Drop test to ensure data card survivability - Feb. 23th
• Thermal test to validate thermal model - Feb. 20th
%
Completion
Start Date
Deadline
Status
Polystyrene Insulation
(x12)
10
2/6
2/18
On Schedule
Three-Arm Cap Plate
(x2)
20
1/29
2/18
On Schedule
Support Arm (x2)
20
1/29
2/18
On Schedule
Internal Hexagonal Cap
(x2)
20
1/29
2/6
On Schedule
Internal Support Arm
(x3)
20
1/29
2/6
On Schedule
L-brackets (x24)
60
1/30
2/11
On Schedule
Task
Background
Schedule
Electronics
Software
Mechanical
Budget
24
Background
Schedule
Electronics
Software
Mechanical
Budget
25
Testing, $100
Current
Expenditures
Structures,
$1,016.53
Structures,
$300
Future Expenses
Margin,
$947
Electronics,
$1,911.97
Remaining,
$1,896.55
Misc., $300
Electronics,
$250
General,
Misc.
$174.95
$174.95
Total Budget:
$5000
Background
Remaining Budget:
$1897
Schedule
Electronics
CDR Margin:
$1500 (30%)
Software
Mechanical
Testing:
Cooler for cold test,
dry ice
Electronics:
Final board revisions,
misc. supplies
Structures:
Foam insulation,
misc. shop supplies
Miscellaneous:
Printing, AIAA
registration
MSR Margin:
$947 (19%)
Budget
26
27
Electrical
• PCB Rev. 1 assembled by Feb. 6th (On Schedule)
• On track to achieve full Level 4 success to measure pressure changes from 0.1-20 Hz
with a 0.1 Pa sensitivity.
Software
• Data Storage Routine completed by Feb. 25th (On Schedule)
• On track to achieve full Level 4 success to operate with an 100Hz sampling frequency.
Mechanical
• Structure manufacturing to be completed March 9th (On Schedule)
• On track to achieve full Level 4 success to survive stratospheric pressure and maintain
internal temperatures between -10 and 45°C.
28
29
30
FR 1
Detects
changes in
pressure from
infrasound
sources from:
Level 4
(Full)
Level 3
Level 2
Level 1
(Minimum)
0.1 – 20 Hz
0.1 Pa Sensitivity
0.1 – 20 Hz
0.5 Pa Sensitivity
0.1 – 20 Hz
1.0 Pa Sensitivity
FR 2
Samples data
at a minimum
rate of:
Maintains
internal
temperature
between:
Records and
stores data for
minimum:
-10 - 45°C
20 hours
4677.89 – 7504.84 Pa
100 Hz
(corresponds to 1821 km)
-
-
-13 - 48°C
16 hours
-
-
-16 - 51°C
12 hours
0.1 – 20 Hz
2.0 Pa Sensitivity
Operates at or
below the
pressures:
FR 3
101 kPa
40 Hz
(corresponds to
ambient sea level)
-20 - 55°C
(min./mix.
operating
temperatures)
6 hours
31
Design Requirements
Designation
Description
The pressure sensors shall register infrasound
DR 1.1
pressure waves of amplitude 0.1-100 Pa.
The pressure sensors shall register infrasound
DR 1.2
pressure waves of frequency 0.1-20 Hz.
An acceleration reference shall be provided with
1.08” x 1.10” x 1.03”
DR 1.3.1
a sensitivity determined by the pressure sensor
Six 0.1” Header Pins
specifications.
Critical Capabilities:
- Differential pressure transducer with a differential range of ±124.5Pa
- Sensitive to pressure waves of 0.044 Hz and up
Supporting Hardware:
- Requires bypass capacitor, ceramic adequate
- Requires ADC interfacing for data collection
- Requires amplification to interface with ADC
- Operates at 7V pulling 1.5mA
Manufacturability Concerns:
- 0.1” headers, can be hand soldered but require bending or additional components to
mount flush with board
- $73.88 each, two extras provided, require long lead time to obtain more replacements
32
Design Requirements
Designation
DR 1.4.1
DR 1.6
Description
The analog to digital conversion shall have a
minimum resolution of 0.01 Pa.
ASTERIA shall collect pressure data with a
minimum signal to noise ratio (SNR) of 5.
Package: MSOP-8
Critical Capabilities:
- Rail-to-Rail input with gain range of 1 to 1000
- 0.005% gain error with 0.5ppm/°C maximum gain drift
Supporting Hardware:
- Requires bypass capacitor, ceramic adequate
- Requires six resistors to set gain, remove errors, and get offset voltage
- Operates at 3.3V pulling 115μA
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $2.76 each, easily replaced if required
33
Design Requirements
Designation
DR 1.4.1
DR 1.4.2
Description
The analog to digital conversion shall have a
minimum resolution of 0.01 Pa.
The analog to digital conversion shall have a
minimum sampling frequency of 40 Hz.
Package: MSOP-12
Critical Capabilities:
- 16-bit conversion, provides resolution of 19.07μV or 3.8mPa
- Selectable sample rate of 208 or 833 samples per second
- 10ppm/°C maximum drift for an independent reference voltage of 1.25V
- 3-Wire + Chip Select SPI interface
Supporting Hardware:
- Requires four bypass capacitors, ceramic adequate
- RC filter applied at input pin
- Operates at 3.3V pulling 3.5mA
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $2.76 each, easily replaced if required
34
Design Requirements
Designation
DR 1.5
DR 1.4.2.1
Description
ASTERIA shall have a data handling system
that manages data collection and storage
processes.
The software and hardware operation and delay
times shall sum to less than 25 milliseconds per
cycle in order to achieve a minimum 40 Hz
sample rate.
Package: 80-pin TQFP
Critical Capabilities:
- 69 available ports, including 2 SPI lines and 2 USART lines
- Can use an external oscillator for clock speeds up to 21MHz (190ns per instruction)
- Has libraries available for most standard functions as well as SD card file systems
Supporting Hardware:
- Requires eight bypass capacitors, ceramic adequate
- Can use an external crystal oscillator for more reliable timing
- Operates at 3.3V pulling up to 100mA
Manufacturability Concerns:
- 0.5mm pitch, can be hand soldered, but reflow faster and easier
- $8.74 each, samples available through Microchip, can be replaced if required
35
Design Requirements
Designation
DR 2.5.2
DR 3.2.1
Description
The data storage system shall store all data onboard for post-flight recovery on a removable
data storage system.
The data storage capacity shall accommodate
storage for data from each pressure sensor and
temperature sensor at a 40 Hz sampling rate for
the 20 hour mission duration.
15mm x 11mm x 1mm
0.5 grams
Critical Capabilities:
- 8GB storage, 0.35GB required for 20 hours of data
- 48MB/s read speed, 5.08KB/s acquisition rate by sensors
- Removable and able to interface with standard computer systems
- Can be written to via 3-Wire SPI
- Water and temperature resistant, survives up to 500G impacts
Supporting Hardware:
- Requires bypass capacitor, ceramic adequate
- Requires a microSD socket
- Operates at 3.3V pulling up to 100mA
Manufacturability Concerns:
- $12.99 each, available at multiple outlet retailers within driving distance
36
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
Package: HTSOP-J8
Critical Capabilities:
- Maximum input voltage of 15V, with a minimum dropout voltage of 1.2V
- Maximum power dissipation of 2110mW
- Maximum 3% error in output voltage
Supporting Hardware:
- Requires 2 bypass capacitors, ceramic adequate
- Temporary: Requires breakout board to interface with debugging board
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $0.69 each, easily replaced if required
37
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
Package: SOT-223
Critical Capabilities:
- Maximum input voltage of 15V, with a minimum dropout voltage of 1.3V
- Maximum 1% error in output voltage, 0.003% output noise
Supporting Hardware:
- Requires 2 bypass capacitors, one tantalum and one ceramic
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $4.52 each, easily replaced if required
38
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
Package: MSOP-8
Critical Capabilities:
- Maximum input voltage of 20V, with a minimum dropout voltage of 0.43V
- Maximum 1% error in output voltage, 20μV output noise
Supporting Hardware:
- Requires 3 bypass capacitors, ceramic adequate
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $3.52 each, easily replaced if required
39
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
Package: SOT-323
Critical Capabilities:
- Maximum input voltage of 13V, with a minimum dropout voltage of 0.3V
- Maximum 3% error in output voltage, 39μV output noise (without bypass capacitor)
Supporting Hardware:
- Requires 2 bypass capacitors, ceramic adequate
Manufacturability Concerns:
- 0.65mm pitch, can be hand soldered or reflowed
- $0.51 each, easily replaced if required
40
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
74mm x 56mm x 19mm
152 grams
Critical Capabilities:
- Li-Ion multicell battery pack, 11.1V nominal with 2200mAh capacity
- 12.8V peak voltage, 6.5A maximum discharge
- Overcharge and overdischarge protection via on board polyswitch
- 70% reduction in capacity at expected temperatures
Supporting Hardware:
- Requires connector to interface with board
- Requires special charger for safe charging
Manufacturability Concerns:
- $27.95 or more, available at multiple online retailers for varying cost
- Requires special handling, must charge using charging bags while observed
41
Design Requirements
Designation
DR 3.1
Description
ASTERIA shall provide necessary power as
dictated by component specifications for a
minimum of 20 hours.
157mm x 40mm x 73mm
770 grams
Critical Capabilities:
- Li-Ion multicell battery pack, 7.4V nominal with 20.8Ah capacity
- 8.4V peak voltage, 14 A maximum discharge
- Overcharge and overdischarge protection via on board polyswitch
- 70% reduction in capacity at expected temperatures
Supporting Hardware:
- Requires connector to interface with board
- Requires special charger for safe charging
Manufacturability Concerns:
- $163 each, require special shipping charges and 5 day lead time
- Requires special handling, must charge using charging bags while observed
42
7.4 V Li-Ion
Battery
8.4V Max
14A Max
5V
Regulator
5V Max
800mA Max
3.3 V
Regulator
3.3V Max
300mA Max
Microcontroller,
MicroSD Card,
USB-USART
Converter,
Temperature
Sensor
Control Board
Microphone Boards
3.3 V
Regulators (x5)
11.1 V Li-Ion
Battery
12.8V Max
6.5A Max
7V
Regulator
7V Max
300mA Max
3.3V Max
50mA Max
Temperature
Sensors (x5),
Analog-to-Digital
Converter (x10),
Op-Amp Chip
(x10)
Pressure
Transducers
(x10)
43
Temp. x6
ADC x10
LTC2470 ADC
Conversion
ADC Write Time and
Delay x10
Margin
SD Card
Conversion Time
0
5
10
15
20
Time Elapsed (ms)
25
30
ADT7320 Temperature
Sensor Write and Delay
x6
SD Card Write Operaiton
Software Timing Loop
•Required each loop under 25 ms
•Assuming Worst Case Timing Scenario
•Loop uses 8.2 ms, worst case
•Provides 16.8 ms margin, or 67%
44
•Physical temperature or pressure values
Raw Data
SPI Sensor
Memory
Buffer
SD Card
•Autonomously collects data (pressure/temp)
•Value sampled through software.
•Two 512 kB RAM buffers
•Incoming data written to active buffer
•Buffer is full, switch buffers write to SD card
•Write inactive buffer to SD card
•Write operation continues independently of software main loop
45
Software
Element
Acquisition
Method
Completed
Hours
Completion
Status
Main Code
Written in
House
1
100%
Data Acquisition
Written in
House
4
10%
SPI Interrupt
Written in
House
0
0%
Read/Write SPI
Pressure
Sensor
Written in
House
1
50%
Read/Write SPI
Temperature
Sensor
Written in
House
1
50%
Prevent
Overflow
Written in
House
0
0%
Initialize SD
Card
Download from
Manufacturer
0
0%
Write to SD
Card
Download from
Manufacturer
0
0%
Compiler
Operating
Software
Complete
by: Feb. 25th
C18 Microchip
Compiler
46
Task Type
Manufactured
Purchased
Background
Item
Method
Progress
Polystyrene Insulation (x12)
CNC Mill
10%
Three-Arm Cap Plate (x2)
CNC Mill
20%
Support Arm (x3)
Knee Mill
20%
Internal Hexagonal Cap (x2)
CNC Mill
20%
Internal Support Arm (x3)
Knee Mill
20%
L-brackets (x24)
Bandsaw/Mill
60%
Hoist Rings (x3)
N/A
Purchased
Nylon Tubing
N/A
Purchased
Wind Barrier Foam
N/A
Purchased
Fixtures
N/A
Purchased
Schedule
Electronics
Software
Mechanical
Budget
47
48
Microphone
Temperature
Sensitivity
Electronic
Software
Integration
Microphone
Acceleration
Microphone
Infrasound NOAA
Wind Barrier – ITLL
Wind Tunnel
Microphone
Infrasound NOAA
Electronics
Testing
Integrated
Testing
Integration and
Flight Duration
CDR
Structural
Loading and
Data Survivability
Survivability
Testing
Software Pre- Flight
Diagnostic
Vacuum
Chamber - JANA
Thermal
49
Design Requirements
Designation
DR 1.1
DR 1.2
Infrasound
Testing
Description
The pressure sensors shall register infrasound pressure waves of
amplitude 0.1-100 Pa.
The pressure sensors shall register infrasound pressure waves of
frequency 0.1-20 Hz.
Verify the requirements for frequency
(0.1 – 20 Hz) and amplitude (0.1-10
Pa) response is met by the pressure
transducer
Strategy
•
•
Vary frequency & pressure amplitude
Self-noise characterization
Location and
Equipement
•
•
Piston Bellows - NOAA
NI 9239 DAQ, LabVIEW
Measurements
•
•
Microphone output voltage
Gear, RPM, and resulting frequency
(accurate to 1-2%)
Issues
•
Electronic noise higher than lowest
amplitude
Gear and
RPM Control
Motor
Bellows
Volume
with Steel
Wool 50
Dial Gauge
Synchronous
Motor and
Gears
Pressure Transducer
Adjustable Eccentric
Sylphon Bellows
Mechanical
Filter
DAQ
Connective Tubing
Open Port
Steel Wool
Measured 0.044 Hz
Pressure Waves
(below 0.1 Hz
Requirement)
Thermal Insulation
Piston Bellows (NOAA)
Simulated Infrasound
Design
Waves Microphone
Background
Overview
(0.1-20Hz)
Thermal
Mechanical
Risks
V&V
Project
Management
51
Gear and RPM
Control
Motor
Background
Pressure
Transducer
To Piston
Bellows
Bellows
Volume with
Steel Wool
Design
Overview
Microphone
Thermal
To Laptop
Mechanical
Risks
V&V
Project
Management
52
0.044 Hz
Pressure
Wave
0.57 Hz
Pressure Wave
1.15 Hz Pressure
Wave
Background
Design
Overview
Microphone
Thermal
Mechanical
Risks
V&V
Project
Management
53
•
•
•
•
•
Microphone Infrasound
Testing
Microphone Acceleration
Testing
Microphone Temperature
Characterization Testing
Electronic Software
Integration Test
Wind Barrier
Shaker Table
Assembly
Reference
Accelerometer
Pressure Transducer
Purpose:
Characterize the microphone’s
sensitivity to accelerations
Procedure &
Strategy
•
Induce low frequency
accelerations to simulate
payload motion at altitude
Location &
Equipment
•
ITLL Shaker Table
Measurements
•
•
Acceleration
Microphone output voltage
Issues
•
Saturation of sensor
diaphragm due to large
response to acceleration
Commanded
Frequency fc
54
•
•
•
•
•
Microphone Infrasound
Testing
Microphone
Acceleration Testing
Microphone
Temperature Sensitivity
Testing
Electronic Software
Integration Test
Wind Barrier
Thermomete
r
Varying
Environment
T °C
Purpose:
Characterize the microphone’s
sensitivity to temperature
Procedure &
Strategy
•
Expose microphone to
varying or controlled
temperature environments
within operational range (15 to 45°C)
Location &
Equipment
•
•
•
•
Dry ice, ice water bath
Large insulated cooler
Temperature sensors
Resistive heating elements
Measurements
•
•
Microphone temperature
Microphone output voltage
Issues
•
Controlled temperature
environment
Pressure
Transducer
Voltage
Data
Out
Temperature
Data Out
Background
Design
Overview
Microphone
Thermal
Mechanical
Risks
V&V
Project
Management
55
•
•
•
•
•
Microphone Infrasound
Testing
Microphone Acceleration
Testing
Microphone Temperature
Characterization Testing
Electronic Software
Integration Test
Wind Barrier
Power
On
SPI
Run
Diagnost
ic
Sensor
Functional
ity
Run Test
Cases
SD
Card
Write
Purpose:
Verify all electronic components
function individually and meet
all electronic performance
requirements
Procedure &
Strategy
•
•
Power on electronics
subsystem with software
loaded onboard
Run diagnostic tests and
various test cases to verify
software and electronics
respond correctly
Location &
Equipment
•
•
•
External power source
Multimeter
Digital logic probe
Measurements
•
•
•
Voltage/Current/Power
Digital Logic/Timing
Data Out
Issues
•
Improper connections
leading to improper data
Port
Check
56
Design Requirements
Designation
Description
DR 1.6
ASTERIA shall collect pressure data with a minimum signal to noise
ratio of 5
Wind Barrier
Test
Strategy
Verify the wind noise reduction
capability of the foam barrier filter
and validate the software model
•
Embed pressure transducer inside foam
wind barrier, vary dynamic pressure
seen by filter/transducer system
Location
•
ITLL Wind Tunnel, Wind Barrier Foam
Hemisphere, Pressure Transducer, Data
Collection Capability
Measurements
•
•
Dynamic pressure
Microphone output voltage
•
Saturation of the microphone at 22 m/s,
test will not exceed this
Issues
Incoming Wind
Wind Barrier
Covered Sensor
57
Design Requirements
Designation
Description
DR 2.6
Maintain structural integrity including gondola connections during
launch and parachute deployment and withstand impact forces up to
2000 N
Drop test
Strategy
•
Expected landing speed of 6.7 m/s
(height of 2.28 m)
Added weight will simulate electronics
Location
•
One story drop – ITLL bridge
Measurements
•
G loading - accelerometers
Issues
•
Safety – maintain perimeter around
drop site
Background
•
Design
Overview
ASTERIA
Structure/Mock
Payload
Measure loading during landing to
verify the SD card will survive (max of
500g)
Microphone
Thermal
Mechanical
Payload
Cavity
Accelerometer
Battery
Fixture to
Payload
Risks
V&V
Project
Management
58
Internal
Payload Test
Configuration
Drop Test
Configuration
(Side View)
Drop Test Configuration
(Top View)
Wall
Impact
Site
Min 8
m
ASTERIA
Structure/Mock
Payload
Monitored
Perimeter
Payload
Cavity
Accelerometer
Battery
or
1 Story
Height
Impact
Site
Fixture to Payload
Impact Site –
Max
Load/Shock
Min 8
m
Design Requirements
Designation
DR 2.3
Strategy
Description
Operate under stratospheric pressure conditions: 5 to 8 kPa
•
Subject critical electronic components to
stratospheric pressure
Equipment
•
Vacuum Chamber - JANA
Measurements
•
•
Chamber pressure
Output from instrument peripherals and
microphone
Issues
•
Safety of electronics and pressure transducer
60
𝑉𝐵𝐷 =
𝐵𝑃𝑔
1
ln 𝐴𝑃𝑔 − ln(ln 1 + )
𝛾
For standard atmospheric pressure air the voltage breakdown through
Paschen’s Law is given in the previous equation where:
• A = 11.25/ m*Pa
• B = 273.77 V/m*Pa
• Γ = 0.01
P and g are variable parameters, P being pressure in pascals, g being
the gap distance in meters
Only battery has
• VBD at 4 kPa (min pressure value):
highest potential
• 8.22V at 1 mm
difference of 11.1V,
• 14.61V at 2 mm
and electrodes
• VBD at 4.7 kPa (pressure value at 21 km):
separated by more
• 9.39V at 1 mm
than 1 mm
• 16.72V at 2 mm
Reference: http://pubs.rsc.org/en/content/articlehtml/2015/an/c4an01101e
Background
Schedule
Electronics
Software
Mechanical
Budget
61
Design Requirements
Designation
Description
Operate in an ambient temperatures of
internal temperature of -10 to 45 ± 1°C
DR 2.5
Experimental
Thermal Test
Verify the thermal model by providing
comparison data. Thermal model will be
used to verify temperature for the flight
duration
Procedure &
Strategy
•
•
Subject the payload (without
electronics) to the temperature
extremes for several hours
Compare results with thermal model
Equipment
•
•
Dry ice and large insulated cooler
Temperature sensors
Measurements
•
Internal and external temperature
-55 to 30°C and maintain
Internal
Temperature
Measurement Side
Insulation
External
Temperature
Measurement Sides
Controlled
Temperature
Environment
62
Design Requirements
Designation
DR 3.1
DR 3.2
Description
ASTERIA shall provide necessary power as dictated by
component specifications for a minimum of 20 hours.
ASTERIA shall be capable of storing onboard a minimum of 20
hours worth of pressure and temperature data.
Integration and
Flight Duration
Test
Verify the entire payload operates when
fully integrated and operates for the mission
duration of 20 hours.
Procedure &
Strategy
•
Run fully integrated payload for a
duration of 20 hours, being monitored at
all times
Equipment
•
Temperature sensors for live data stream
of internal payload
Measurements
•
Internal temperature, payload
temperature and microphone data
63
Design Requirements
Designation
Description
DR 3.3
A pre-flight checkout and status test shall be performed prior to a
flight to ensure that all components are able to operate
autonomously during the flight
Pre-Flight
Diagnostic Test
Verify the pre-flight diagnostic software will
correctly detect the problem
Procedure &
Strategy
•
Run test case scenarios to ensure the
diagnostic software correctly detects the
problem
Equipment
•
Completed payload and electronics
Measurements
•
Software diagnostic output
64