TEAM TOTAL RESISTANCE
PRELIMINARY DESIGN REVIEW
Brittany Dupre
Jason Mueller
Jeff Weinell
1
MISSION GOAL
Team Total Resistance will build a
payload to measure Earth’s gravity field
as a function of altitude for heights of up
to 100,000 feet (30,480 meters), and
compare our findings to theoretical and
experimental high altitude gravity
models.
2
SCIENCE OBJECTIVES
The payload shall take measurements to show
an approximately linear decrease in the
relative change of gravitational acceleration
as a function of altitude to 30,480 meters.
Team Total Resistance shall analyze data
recorded by the payload.
3
SCIENCE BACKGROUND
 This graph shows
the theoretical
change in gravity as
function of altitude
according to
Newton’s second
law.
 As the payload’s
altitude increases,
we expect to see a
slight decrease in
gravitational
acceleration.
Figure 1. Change in gravity with increasing altitude
4
SCIENCE BACKGROUND
Figure 2. Experimental data from the DUCKY Ia
5
TECHNICAL OBJECTIVES
Team Total Resistance shall comply with all
LaACES requirements.
The payload shall protect internal components
from balloon interface conditions and ambient
environmental conditions.
6
TECHNICAL BACKGROUND
 The position of the payload
from a fixed point on Earth’s
surface can be determined
by the position of the balloon
relative to a fixed point on
Earth and the payload’s
position relative to the
balloon using the following
equation:
𝒓 = 𝒓 0 + 𝒓′
y
𝑟′
𝑟0
𝑟
 To find the acceleration:
𝒂 = 𝒂 0 + 𝒓 ′ + 𝝎 × 𝒓 ′ + 2𝝎 × 𝒓 ′ +
𝝎 × 𝝎 × 𝒓′
𝑥
Figure 3. Relative position of payload to
balloon
7
TECHNICAL BACKGROUND
 Team Total Resistance will use coordinates from the
GPS receiver that correspond to the position of the
ACES balloon at the time each payload measurement
is taken.
 Team Total Resistance will time stamp each
measurement according to hours, minutes, seconds,
such that the starting time is synchronized with the
clock that ACES staff will use for GPS
measurements.
8
TECHNICAL BACKGROUND
Accelerometers
measure an
object’s proper
acceleration.
Figure 4. A capacitive MEMS accelerometer
design showing the moveable plates and
fixed outer plates
9
TECHNICAL BACKGROUND
 A 3-axis magnetometer measures
the intensity of magnetic flux
density along three perpendicular
axes.
 The payload will obtain
measurements to determine the
angle between the sensing axis
and the direction of gravity.
 Digital MEMS magnetometers
usually contain temperature
sensors and signal conditioning
circuitry to correct for temperature
bias.
Figure 5. A diagram showing how
Earth’s core generates a magnetic
10
field
TECHNICAL BACKGROUND
 When the rotor is
spinning at high speeds,
a gyroscope will remain
stable oriented in the
same direction
independent of its
position.
Figure 6. A diagram of different parts of a
mechanical gyroscope
11
TECHNICAL REQUIREMENTS
 Team Total Resistance shall comply with all LaACES
requirements.
 The payload shall take enough measurements to
show a trend in the relative change of gravitational
acceleration as a function of altitude .
 The payload shall take measurements in order to
calculate relative gravitational acceleration changes
m
to a minimum accuracy of 4.5 × 10 −3 2 .
s
 Team Total Resistance shall analyze data recorded
by the payload.
12
SYSTEM DESIGN
Figure 7. System Design
13
SENSORS
 Type: MXC6226XC
MEMS Accelerometer
 Size: 1.2 mm x 1.7 mm
x 1.0 mm
 Temperature range: -20
to 70 degrees Celsius
 Operating voltage: 2.5
to 5.5 volts
Figure 8. A picture of a micro electromechanical system (MEMS) ADXL330
accelerometer and finger for size
comparison
14
SENSORS
 Type: LSM303DLHC
Magnetometer
 Temperature range: -40
to 85 degrees Celsius
 Operating voltage: 2 to 4
volts
Figure 9. A LSM303DLHC magnetometer by
STMicroelectronics
15
SENSORS
 Type: PS-MPU-6100A
Gyroscope
 Temperature range: -40
to 85 degrees Celsius
 Operating voltage: 2.4
to 3.5 volts
Figure 10. A PS-MPU-6100 by InvenSense
16
SENSOR INTERFACE
Figure 11. Schematic of a capacitive
accelerometer
Figure 12. Schematic diagram of type
MPU-6100 gyroscope
17
SENSOR INTERFACE
 Schematic
diagram of the
LSM303DLHC
Magnetometer
 Can be
programmed by
the user using
the I²C interface
Figure 13. A schematic of a LSM303DLHC
18
SENSOR INTERFACE
 Schematic
diagram of
ADIS16400
 Has a 3-axis
accelerometer,
a 3-axis
magnetometer,
and a 3-axis
gyroscope
Figure 14. An ADIS16400 multi-sensor by iSensor
19
POWER BUDGET
Table 1. Power budget.
Device
Current
Voltage (V)
mA/hr
BalloonSat
(microcontroller)
Accelerometer
80 mA
+9 to +15
320
500 µA
+4 to +6
2
Magnetometer
110 µA
+2 to +4
.44
Gyroscope
3.6 mA
+2 to +4
14.4
ADC
4 mA
0 to +3
16
Total
89 mA
+9 to +15
353
20
FLIGHT SOFTWARE DIAGRAM
 Functional
software flowchart
that demonstrates
how the software
will function.
Figure 15. Flight software diagram
21
THERMAL DESIGN
Our payload must function within an ambient
temperature range of -60 to 38 degrees
Celsius.
The payload structure will be made out of
polystyrene.
We will use Gorilla Glue as the polystyrene and
wood adhesive.
22
MECHANICAL DESIGN
 Isometric view of
preliminary
hexagonal-prism
payload structure
Figure 16. Isometric view of our payload
23
MECHANICAL DESIGN
Figure 18. A schematic of our payload structure
24
WEIGHT BUDGET
Table 2. Weight Budget.
BalloonSat
Sensing Unit
BalloonSat
23%
Payload Structure
BalloonSat
Sensing Unit
1.9%
Payload Structure 75%
Figure 19. Weight budget pie chart
Component Weight
Approximation
(grams)
61.5
Sensing
Unit
5
Payload
Structure
200
Total
266.5
Remaining
Allowed
233.5
25
PAYLOAD DEVELOPMENT PLAN
 Software Design Development
 The software shall be written to perform the required
tasks.
 The software shall be run and tested on the BalloonSat.
 Revisions to the software will be made is bugs are found.
26
PAYLOAD DEVELOPMENT PLAN
 Electrical Design Development
 We shall test and calibrate all chosen sensors.
 Each sensor shall go through temperature and pressure testing.
 After testing is completed, the circuitry must be completed for each
sensor.
 A complete power budget will be completed.
27
PAYLOAD DEVELOPMENT PLAN
 Mechanical Design Development
 The amount of payload insulation, payload volume, and weight
distribution all depend on the choice of sensors.
 We will calculate theoretical ultimate stress values for the payload.
 The dimensions of the payload will be determined by preliminary
circuit design and weight requirements dictated by ACES .
 We will determine how the top of the payload is going to remain
closed.
28
RISK MANAGEMENT
Table 3. Identified Risks
Risk Event
Likelihood
(Low=1, High=5)
Impact
(Low=1,
High=5)
Detection
Difficulty
(Low=1, High=5)
When
1
Impact causes damage to payload memory
1
5
1
Flight
2
Payload rotation rate exceeds measuring range of 2
gyroscope
Magnetic interference from other electronic
2
devices causes magnetometer error
4
2
Flight
3
5
Flight
Timing between payload and balloon beacon data 1
is not set correctly
The EEPROM runs out of storage space due to
2
improper calculations of bytes per measurement
3
1
Preflight
4
2
Flight
6
7
Flight is delayed
The power source’s amp-hours are too low
3
2
2
4
1
2
Preflight
Flight
8
The power source’s current degrades with
temperature at an amount that causes an
electronic device to fail
The payload is too heavy
The payload gets rained on
2
4
2
Flight
1
2
4
3
1
1
Preflight
Flight
3
4
5
9
10
29
RISK MANAGEMENT
11
Rapid depressurization causes payload
structural damage
Shipping is delayed for parts included in
payload design
Parts included in payload design are no
longer manufactured
Software does not convert between
computers
All software needed for post analysis is
not on a team member’s laptop when we
arrive at Palestine, Texas
The WFM crashes
1
4
1
Flight
3
3
3
Preflight
2
3
1
Preflight
2
2
1
Post Flight
1
3
1
Post Flight
2
4
2
Throughout Project
1
5
2
Post Flight
2
5
4
Throughout Project
2
3
3
Throughout Project
20
Position measurements are not available
from ACES management
Units are not all converted to
International System of Units (SI)
Binary, hexadecimal, etc. language is
not translated correctly
The sensing axes are not stable
3
3
2
Flight
21
A team member quits
2
5
3
Throughout Project
12
13
14
15
16
17
18
19
30
RISK MANAGEMENT
Figure 20. Risk severity matrix
31
CONTINGENCY PLAN
Table 4. Contingency Plan
Risk Event
Impact causes damage to payload
memory
Payload rotation rate exceeds
measuring range of gyroscope
Response
Reduce
Contingency Plan
Prepare failure analysis
Reduce
Analyze data that are within
measuring range
Magnetic interference from other
electronic devices causes
magnetometer error
Timing between payload and
balloon beacon data is not set
correctly.
The EEPROM runs out of storage
space due to improper calculations
of bytes per measurement
Flight is delayed
Reduce
Move the magnetometer to a
different position in the
payload
Reset payload to Coordinated
Universal Time (UTC)
7
1
2
3
4
5
Reduce
Trigger
Responsibility
Memory is missing or
Jeff Weinell
unreadable
Measurements are at limits of Brittany Dupre
operating range or missing
Magnetometer does not
Brittany Dupre
record correctly during
payload testing
Verify that the time recorded Jason Mueller
by the payload matches UTC
time
Less measurements were
Jason Mueller
taken than planned
Reduce
Memory expansion
Transfer
Be patient
Flight time has passed and the ACES Staff
balloon is on the ground
The power source’s amp-hours are
too low
Reduce
Failure Analysis
8
The power source’s current
degrades with temperature at an
amount that causes an electronic
device to fail
Reduce
Failure Analysis
9
The payload is too heavy
Reduce
10
The payload gets rained on
Retain
Identify methods to reduce
weight
Retrieve usable data
Multimeter displays current
that is too low for circuitry to
work
The circuitry fails during
thermal testing, and
multimeter displays current
that is too low for circuitry to
work
The scale reads over 500
grams
The payload is wet
6
Brittany Dupre
Brittany Dupre
Jeff Weinell
ACES Staff
32
CONTINGENCY PLAN
11
Rapid depressurization causes
payload structural damage
Reduce
Rebuild payload with an
increase in ultimate stresses
12
Shipping is delayed for parts
included in payload design
Parts included in payload design
are no longer manufactured
Retain
Work on other tasks
Retain
Use different parts
Software does not convert
between computers
All software needed for post
analysis is not on a team
member’s laptop when we arrive
at Palestine, Texas
The WFM crashes
Reduce
Download software that
works
Download software from
WFM
Transfer
Reduce
Reduce
Change them to SI
Correct it
20
Position measurements are not
available from ACES
management
Units are not all converted to SI
Binary, hexadecimal, etc.
language is not translated
correctly
The sensing axes are not stable
Get the files from ACES
computer.
Failure analysis
Reduce
Redesign internal structure to Shock testing and
stabilize sensing axes
calibration
Jeff Weinell
21
A team member quits
Retain
Divide tasks amongst remain The team member informs
team members
the other members
Remaining group members
13
14
15
16
17
18
19
Reduce
Retain
The payload is in multiple
pieces as a result of pressure
testing
The part(s) didn’t show up
on time.
Customer service says that
the part is no longer
available
Error message appears
Jeff Weinell
Jason Mueller
Jason Mueller
Jason Mueller
The team member informed Jason Mueller
other members that the
software is not on their
computer
WFM is unavailable
ACES Staff
ACES Staff informs the
groups
ACES Staff
Calculations errors
Program errors
Jason Mueller
Jason Mueller
33
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Questions?
38