Safeguarding the Three Corner Sat Constellation

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Safeguarding the Three Corner Sat Constellation

• By
• Stephen Levin-Stankevich
• Stephen Nauman

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Mission Overview

• Joint project between the University of Colorado,
  Arizona State University, New Mexico State
  University, and AFRL.
• Demonstration of formation flying.
• Stereoscopic imaging to determine cloud heights.
• Demonstrate capabilities of innovative artificial
  intelligence software, CASPER, developed by JPL.

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Mission Requirement

• The mission should demonstrate constellation
  autonomy by using SCL.
• The on-board system shall perform constraint and
  rule checking.
• The mission shall use SAMMI as the ground station
  user interface.

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Autonomous Safeguarding

• SCL
• Stores each hs set in database.
• Rules can react to faults in the hs.
• Real-time analyses of system values for
  constraint checking

• CASPER
• Analyzes resources before starting a task.
• Continuously re-evaluates the schedule.
• Avoids conflicts with locked resources.

5
SCL Overview

• A scripting language used to carry out tasks that
  require many flight software commands to the
  hardware.
• Contains a database for each satellite that
  carries the most recent health and status.
• Performs continuous rule checking for analysis of
  satellites health.

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SCL Rules

• Rules are a reaction to an event that already
  occurred on satellite.
• Allow for solutions to failure mode effects.
• Autonomous safeguarding of satellite

• Rule change_master
• Subsystem none
• Category power
• Activation yes
• Continuous no
• if volt_batt lt 10.5 and master_sv
  satellite_name_sv then
• --give master duties to diff. Sat.
• execute schedule_change_master in 1 tick
• end change_master

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SCL Constraints

• Constraints allow for prevention of faults on the
  satellite.
• function reject_crosslink dest_sat
• if dest_sat 1 or dest_sat 2 or dest_sat 3
  then
• if isl_mode_sv 0 then
• rtedebug "cannot send via crosslink
  because out of isl mode"
• return yes
• end if
• end if
• return no
• end reject_crosslink

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Constellation Commanding

• One satellite is designated as master and
  controls the other two designated as slaves.
• CASPER runs on the master only.
• SCL controls each slave autonomously.

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What is SAMMI?

• SAMMI is a GUI that allows the mission operator
  to control and monitor the Satellite.
• SAMMI consists of
• The main page Monitor all three satellites at
  once.
• Three master pages Monitor all the sub-systems
  of each satellite.
• The subsystem pages Display all the values
  retrieved from the health and status
• The plots Will plot the hs values over time.

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What will SAMMI do?

• Retrieve data from the health and status package
  sent by the satellite.
• It will display these values on the screen with a
  sensor that will determine if they are within
  nominal ranges.
• A history of these values can also be displayed
  in a graph.
• Retrieve data from STK and tell the user when the
  satellite will be in range of a ground station.
• Interface with SCL, so the user will be able to
  issue commands from the SAMMI master page.
• The user will be able to find and see the
  problems easily.

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Summary

• SCL will provide autonomous safeguarding of the
  satellite
• Rules will continuously monitor sensors and
  states to protect the satellite
• SAMMI will allow quick error detection and
  analyses on the ground.

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Acknowledgements

• Colorado Space Grant Consortium
• Air Force Research Laboratories
• University of Colorado Space Grant Staff
• Dave Beckwith
• Elaine Hansen
• Chris Koehler
• Elaine Hansen