DemoSat IV:
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Transcript of DemoSat IV:
DemoSat IV:
RedRoverSatRedRoverSat
University of Colorado at Boulder
Jaime Catchen, Chris Homolac,
Emily Walters
Jaime Catchen, Chris Homolac,
Emily Walters
August 9, 2006August 9, 2006
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Mission Statement & Goals:
RedRoverSat is an autonomous rover
designed to measure wind speed and direction and the moisture of the soil at its landing site. This research hopes to
be beneficial to understanding the objectives of the
Astrobiology Field Laboratory.
Launch
Thermal system heats payload
Payload lands
C&DH senses landing
After rover senses landing, rover detaches from flight line
Rover moves four times in a pre-programmed path and stops for one
minute to run experiments and record data
Recovery
Mission Timeline
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Benefits to NASA:
• Students working on the design of autonomous payloads with moving parts
• The rover will perform experiments similar to those that will be part of the Astrobiology Field Laboratory
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Project Management:
Project start date: May 22, 2006Project start date: May 22, 2006
ScienceChris Homolac – WindJenny O’Brien – WindEmily Walters – Soil
C&DHJaime CatchenChris HomolacLeon Slavkin
StructuresRebekah Hanson
Leon SlavkinEmily Walters
Power/Thermal
Chris Homolac
Project ManagementJaime Catchen
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Design: Structure
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Design: C&DH
Atmega32— 32 Kb programmable flash, 1
Kb EEPROM— 32 I/O pins— 8 analog inputs — Software in C programming
language
H-bridge Motor control
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Design: Landing Sensors
Accelerometer checks stability of the rover every 30 seconds for 5 min.
Temperature and/or Pressure Sensors confirm that rover is not at high altitude.
Safety Timer ensures that rover does eventually deploy, no single point of failure.
Safety TimerIf >30 Minutes
AccelerometerIf Stable for
5 min
Control Timer
2:15 hours
Temperature SensorIf >16 C
PressureSensor
If > 83 kPa
Detach From Flight Line
No
Yes Yes
Yes
No
No
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– Soil probe measures the voltage across the two metals
– Driven by servo
Design: Science
Wind Soil
NiCr Wire
Panel for Wire 1
Panel for Wire 2
Servo mount
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Design: Power & Thermal
Power– Lithium Polymer [11.1V
2100 mAh] Heaters/Main systems
– Lithium 9V Battery Deployment Nichrome
Thermal– Series of (6) 5W 4Ω Ceramic Resistors
– Foam/Aluminum tape insulation
– Thermostat Control
Lithium Polymer Power Supplywith insulation and heaters
Lithium 9V Battery/Resistance Heater
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Design: Budgets
Total Cost $730.00
Total Mass 1658 gMass Budget
C&DH
Power &
Science
Structures
Thermal
Monetary Budget
Power &
Structures
C&DH
Science
Thermal
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Testing
Test Results
Subsystem Check All subsystems met requirements
Rover path test Rover can maneuver around obstacles
Data logging test Science data was stored to EEPROM
Drop test Mild damage to Aluminum Frame
Whip test No damage to structure or nichrome circuit
Full mission test (x2) Rover’s thermal subsystem kept components at required temperatures,
Nichrome tried to melt line, servos deployed
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Results
Recovery• Both wheels came off during landing• Flight line Nichrome was broken• Flight line torn• Servos tried to deploy science experiments in proper orientation• Soil probe bent, wind panel bent• Wind Nichrome broken
Post Flight• No data stored to EEPROM• Battery discharged to 8v• H-bridge, battery, right motor, heaters, servos, AVR still in working order• Motor gears stripped
Wheel Hub
Motor Shaft
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Improvements and Lessons Learned
Improvements to the Design• Put wheels inside frame• Write a byte to EEPROM periodically throughout flight code • Put experiments inside structure or make rover a vessel for any experiment• Mechanical detachment mechanism instead of Nichrome
Lessons Learned• No test like the actual flight• Dealing with unpredictability of flight circumstances and landing site
DemoSat IV:
Questions?Questions?
University of Colorado at Boulder