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