1
TEAM TESLA
Anthony Thompson
Philip de la Vergne
Aaron Wascom
Brandon Sciortino
2
Overview
• Address concerns from previous PDR presentation
• Polarity
• Humidity
• Temperature
• Linear Actuator
• Breakdown Voltage at Sea Level
• Data Accuracy
• Data Frequency
• Requirements
• System Design
• Traceability
• Software
• Principal of Operation
• Payload Development
• WBS
3
Polarity
A comparison of breakdown voltages for
positive and negative corona
4
Humidity
Effect of absolute humidity on the breakdown voltage of a 30cm
point-to-plane spark gap
Parameter: Voltage
Positive D.C Voltage
A.C. Voltage
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Temperature
Lower temperatures mean slower molecules, which means that the particles in
the air collide with less kinetic energy.
This drop in energy apprehends the production of ions and free electrons,
which decrease the current created through the corona breakdown mechanism
6
Data
• If the payload passes through a cloud the humidity will
change rapidly making Its effect on the breakdown voltage
more evident.
The Smallest cloud () is about 1000 ft. tall so it insure we
get a measurement inside the cloud we will measure no
less than every 500 feet
We ascend 1000 ft. per min and want to sample every 500
ft. so we will measure every 30 second's .
• How accurate to our results need to be?
• Temperature, Pressure, Humidity, Current, Voltage
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Linear Actuator
• Data must be taken every 500 feet.
• A actuator will increase the distance across the spark gap
to prevent a breakdown and the distance at that instant
will be recorded.
• An analysis of the expected results of this method reveals
that it is not plausible.
• The linear actuator would have to change the spark gap
19 mm every 500 ft.
• Assuming a constant voltage of 3000 V, the sea level
pressure distance product on the x-axis of Paschen’s
curve is 3 Torr-in. This requires a gap distance of 1.002
mm the gap distance would have to change by 19
micrometers every
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Technical Requirements
• The payload shall have a temperature sensor that can measure
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from 40 °C to -70° C and operate throughout the flight.
The payload shall measure Temperature to an accuracy of 1
degree Celsius
The payload shall measure Pressure to an accuracy of 1 Pa
The payload shall have a humidity sensor that can measure 0 to
100% relative humidity and operate throughout the flight.
The payload shall measure relative humidity to an accuracy of 1%
The payload shall have a pressure sensor that can measure 101.3
kPa to 1 kPa and operate throughout the flight.
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Technical Requirements
• The payload shall provide up to 4.5 kV in order to create a
corona discharge at ground level
• The electrodes shall have a point to plane configuration
• The payload shall have a 1 mm spark gap
• The electrodes shall be properly conditioned to provide a smooth
finish
• The anode shall be composed of a gold-plated copper point and
the cathode shall be composed of copper
• The payload shall weigh less than 500 grams.
• The payload shall have two holes 17 cm apart for interfacing with
the LaACES balloon.
• Record and store data from flight so that it can be retrieved after
flight for analysis
• The payload will have enough power to operate throughout entire
flight.
10
Science Requirements
• The electrodes shall be exposed to external temperature and humidity
conditions
• This payload shall consider a corona discharge of 10-5 Amps to be a
breakdown
• The payload shall increase the voltage with an accuracy of
• The electrode configuration shall create a positive corona discharge
• The onboard electronics shall be protected by a Faraday Cage around the
spark gap
• The payload shall record data every 500 feet to observe any clouds in the
flight profile
• The payload shall record temperature, pressure, humidity, and breakdown
voltage from 0 to 100,000 feet
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System Design
12
Principle of Operation
• Measure pressure, temperature, humidity, breakdown
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voltage, and current across the spark gap
Sensors: Piezoelectric, thermistor, relative humidity
Exposed to environmental conditions
Voltage across spark gap increased until 10 microamps
are measured
Voltage comparator observes corona discharge
Switch opened, data recorded, voltage set to zero
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Electrical Development
• Temperature Sensor
• Select sensor that operates within requirements
• Measure from -70 to 40 degrees Celsius
• Operates within 40 degrees Celsius
• Accurate to +/- 1 degree Celsius
• Order Sensor
• Draw preliminary schematic
• Measure accuracy and compare to data sheet accuracy
• Calibrate sensor according to difference between data sheet and
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observed accuracy
Determine necessary gain for op-amp conditioning circuit
Select resistors for op-amp circuit
Test to operate under 100% relative humidity
Test performance in thermal/pressure environments
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Electrical Development
• Pressure sensor
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• Select sensor that operates within requirements
• Measure from -70 to 40 degrees Celsius
• Operates within 40 degrees Celsius
• Accurate to +/- 133 Pa
• Order Sensor
Draw preliminary schematic
Measure accuracy and compare to data sheet accuracy
Calibrate sensor according to difference between data sheet
and observed accuracy
Determine necessary gain for op-amp conditioning circuit
Select resistors for op-amp circuit
Test to operate under 100% relative humidity
Test performance in thermal/pressure environments
15
Electrical Development
• Humidity sensor
• Select sensor that operates within requirements
• Measure from -70 to 40 degrees Celsius
• Operates within 40 degrees Celsius
• Accurate to +/- 1%
• Order Sensor
• Draw preliminary schematic
• Measure accuracy and compare to data sheet accuracy
• Calibrate sensor according to difference between data sheet and
observed accuracy
• Determine necessary gain for op-amp conditioning circuit
• Select resistors for op-amp circuit
• Test to operate under 100% relative humidity
• Test performance in thermal/pressure environments
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Current Detection
• Flight simulation
• Compare to expected results to confirm system design
• Draw Preliminary Schematic
• Select resistor for voltage comparator circuit
• Must allow for 10 microamps created at lowest voltage created
• Select threshold voltage across resistor for voltage comparator
• Select voltage comparator from threshold voltage, environmental
requirements and 2ms response time
• Operate from 40 to -70 degrees Celsius
• Select JK Flipflop
• Operate from -70 to 40 degrees C
• 2ms response time
• Determine high voltage at JK Flipflop for high at BASIC Stamp
• Select transistor
• Response time less than 2ms
• Test transistor to confirm response time
• Purchase materials for electrode configuration
• Test to determine breakdown voltage at sea level
• Finalize circuit schematics
• Flight simulation
• To confirm system design
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Mechanical Development
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Determine required volume to contain components
Determine method of component attachment to payload
Determine required dimensions for interfacing and components
Thermal test to determine required thickness
Shock test
Add to weight budget
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Software Development
• Read/Write to EEPROM
• Determine syntax needed to input and output data to
EEPROM
• Develop subroutine to write data to EEPROM
• Develop subroutine to prevent overwriting
• Test to confirm coding
• Reading sensors
• Develop subroutines to
• Record data from ADC
• Read data from EEPROM
• Timestamp data
• Control Voltage
• Develop subroutine to increase voltage
• Test output voltage sent to DAC from BASIC Stamp
• Ensure HVDC output voltage is the same value indicated by
BASIC Stamp
• Develop subroutine to record breakdown voltage
• Develop subroutine to remove voltage across spark gap
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Mission Development
• Full flight simulation prior to trip
• Bring extra batteries, sensors, voltage comparator, JK flipflop,
resistors, and HVDC
• Assemble payload 24 hours prior to launch
• Test operation off all components prior to launch
• Launch
• Run Pre-flight software that leads into operations software
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HVDC Development
• Select and order HVDC based on electrode testing
• Required breakdown voltage from materials testing
• Draw Preliminary Schematic
• Test and compare measured accuracy to data sheet
• Calibrate HVDC according to difference between data sheet and tests
• Determine required input voltages to create desired output voltages
• Test performance in thermal/pressure environment
• Draw finalized schematics
• Flight simulation
• Compare to expected results to confirm system design
• Add all sensors to weight and power budget
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WBS
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WBS
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WBS
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Overview
• Mission Goal
• Science Objectives
• Technical Objectives
• Science Background
• Science Requirements
• Technical Requirements
• System Design
• Power Budget
• Software Design
• Structural Design
• Management
25
Mission Goal
• To study the effects of humidity and temperature on the
corona breakdown of the atmosphere in an effort to
prevent sparking and ensure safety on future payloads.
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Science Objectives
• Observe the effect of temperature on corona breakdown
voltage of the atmosphere
• Observe the effect of humidity on corona breakdown
voltage of the atmosphere
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Technical Objectives
• Measure temperature of the atmosphere
• Measure pressure of the atmosphere
• Measure humidity of the atmosphere
• Measure the corona breakdown voltage as a function of
pressure and gap distance
• Measure the current across the gap
• Meet all payload standards set by LaACES
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Paschen’s Curve
http://www.sciencedirect.co
m/science/article/pii/S1466
85640200067X
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Electron Avalanche
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Electrode Geometry & Polarity
http://etd.auburn.edu/e
td/bitstream/handle/10
415/2044/Lipham_Mar
k_Thesis.pdf?sequenc
e=1
31
Effects of Humidity
• Humidity has an effect on the corona breakdown voltage
by rearranging the polar water molecules entering the
electric field.
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Effects of Temperature
• Temperature has an effect on the corona breakdown
voltage through increasing the kinetic energy of the
molecules within the spark gap.
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Electrode Material
http://ieeexplore.ieee.or
g/xpls/abs_all.jsp?arnu
mber=13866&tag=1
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Electrode Roughness
http://www.elect.mr
t.ac.lk/HV_Chap1.p
df
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Environmental Conditions
Team
Philosohook’s
Results
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Science Requirements
• The electrodes shall be exposed to external temperature
and humidity conditions.
• This payload shall successfully create a corona
discharge.
• The electrode configuration shall create a positive corona
discharge.
• The payload’s onboard electrons shall be protected with a
Faraday cage.
37
Technical Requirements
• The payload shall have a temperature, pressure, and
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humidity sensor that can measure and operate throughout
the flight.
The payload shall detect a corona discharge by
intercepting a radio interference and detecting a current
spike.
The payload shall have an HVDC Converter.
The electrodes shall have a point-to-plane configuration.
The electrodes shall be properly conditioned.
The anode shall be composed of a gold-plated copper
point and the cathode shall be composed of copper.
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High Level System
Diagram
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HVDC Converter
SMHV Series sub-miniature regulated HV DC
• 0.434 cubic inch converter
• 0 to 10kV at 1 W of power
• 5VDC input
• On/Off Pin
• Voltage and Current monitor outputs
• Current Limiting Control inputs
• SHORT LEAD TIME
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Current & Radio Wave Sensor Interface
V out
Peak
Detector
Conditioning
V out
ADC
RW
Sensor
Conditioning
Resistor
Current
Monitor
Pin
V out
Conditioning
ADC
ADC
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Power Budget
Component
Current
Voltage
Power
Flight Time
Capacity
Full Load – 300 mA
5V
1500 mW
4 minutes
20 mA-hours
SMHV Series
EMCO
Stand by – 20 mA
5V
100 mW
3 hours 56
minutes
79 mA-hours
Humidity Sensor
200 μA
2.7 V
2.5 mW
4 hours
2 mA-hours
BalloonSat
52 mA
12 V
1790 mW
4 hours
208 mA-hours
Pressure Sensor
2 mA
12 V
24 mW
4 hours
8 mA-hours
1 mA
12 V
12 mW
4 hours
4 mA-hours
5V
.8 mW
4 hours
.64mA-hours
Stand by – 1930 mW
Full Load – 3330 mW
4 hours
322 mA-hours
HVDC Converter
HIH-5030 Series
1230 Series
Measurement Spec
Temperature
Sensor
44000 series
OMEGA
DAC
160 μA
Full Load – 355.2 mA
Stand by – 75.2 mA
Totals:
12 V
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Power Source
AAA Energizer L92: Lithium vs. Alkaline
http://data.energizer.com/PD
Fs/l92.pdf
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Flight Software
Flowchart
Temperature: 1 byte
Humidity : 1 byte
Pressure : 1 byte
Time : 3 bytes
Voltage : 2 byte
Voltage Redundancy: 2 byte
Current : 1 byte
Current Redundancy :1 byte
Radio : 1 bit
Total : 97 bits
44
Thermal Design
Device
ADC, RTC, BASIC Stamp,
EEPROM, DAC
Pressure Sensor
Humidity Sensor
Temperature Sensor
HVDC
Current Sensor
Upper Temp (°C)
Lower Temp (°C)
80
-40
125
-40
125
-50
120
-80
85
-55
85
-40
60
-40
Energizer Lithium Batteries
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External Structure
1.2cm
15cm
17cm
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Internal Structure
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Weight Budget
Item
BalloonSat
Signal Conditioning
Mass
Uncertainty
Measured or Estimated
67.6 g
± 5g
Measured
70 g
±5
Estimated
100 g
± 10g
Estimated
15g
±5g
Estimated
150g
±10g
Estimated
402.6g
±35g
and Sensors
Packaging
Wiring
Power Supply
Totals:
48
Group Structure
Functional Group
Team Member
Project Management
Anthony Thompson
Science Requirements
Chris Rowan
Electronics
Aaron Wascom
Flight Software
Aaron Wascom
Mechanical Integration
Philip de la Vergne
System Testing
Brandon Sciortino
Data Processing and Analysis
Anthony Thompson
Documentation
Chris Rowan
49
WBS
50
Milestones
51
Risk Management
Risk Event
Likelihood
Impact
Detection Difficulty When
Faulty Power Supply
4
5
2
Flight
Faulty Preflight
Procedure
2
4
4
Pre-Flight
Incorrect Coding
3
5
1
Calibration
Sparking
Losing a Team
Member
3
2
3
3
2
1
Flight
Pre-Flight
Faulty Parachute
1
3
1
Flight
Component Failure
4
4
2
During Flight/ Testing
Impurities on
Electrode Surface
3
4
2
Pre-Flight/During
Flight
Loss of Payload
3
5
5
Post-Flight
External Deadlines
not Met
2
5
3
Pre-Flight
Over Budget
3
4
2
Pre-Flight
Memory Deficiency
4
4
3
Flight
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Risk Event
Response
Contingency Plan
Trigger
Responsibility
Faulty Power Supply
Reduce
Switch out with new
Batteries
Sensors Malfunction or
Break
Philip de la Vergne
Faulty Preflight
Procedure
Reduce
Pre-Flight To-Do list
Pre-Flight Set up
Anthony Thompson
Incorrect Coding
Reduce
Recode
Will not load to BASIC
Stamp
Aaron Wascom
Sparking
Reduce
Electrode geometry,
sparking type, and
Faraday cage
Faulty Programming
Aaron Wascom
Losing a Team
Member
Reduce
Work is shared among
remaining members
Sudden Workload
Increase
All Members
Faulty Parachute
Transfer
Build payload to protect
data storage
Parachute failure
Dr. Guzik
Component Failure
Transfer
Order another from a
Device does not operate
different company or have properly
a spare
Aaron Wascom
Impurities on
Electrode Surface
Reduce
Check surfaces prior to
launch
Condensation or dust
Brandon Sciortino
Share
Prepare Failure Report
Lack of Payload
All Members
Transfer
Pray we don’t get fired
Lack of Project
Management
All Members
Loss of Payload
External Deadlines not
Met