Test and Verification of a CubeSat Attitude Determination and Control System in Variable Magnetic Fields

Abstract

The Center for Space Research and Assurance (CSRA) at the Air Force Institute of Technology (AFIT) continues to explore CubeSat initiatives for solving many current space security issues. Regardless of the mission requirements, the success of the CubeSat on orbit frequently depends on the Attitude Determination and Control System (ADCS) functioning correctly. Previous research at AFIT has demonstrated single axis control on a spherical air bearing test bed incorporated within a Helmholtz cage utilizing artificially strong magnetic fields for better signal to noise ratios which are not experienced on orbit. This research explores the process of redesigning, testing, and programming a new 6U CubeSat ADCS to operate in representative magnetic fields using a three wheel reaction wheel array (RWA). A second external magnetometer is utilized while its effect on the quaternion estimate (QUEST) is characterized. The RWA is modularized and displaced from the ADCS controller by the addition of a separate controller on the RWA to handle Hall sensor interrupts allowing the control and estimation task to run uninterrupted. The displacement of the RWA from the primary ADCS controller, which includes the primary magnetometer, minimizes electromagnetic disturbances caused by the RWA on the magnetometer. A quaternion error Proportional-Integral-Derivative (PID) control law is used to control the ADCS test bed while an external motion capture system captures its true orientation. This research effort shows that the quaternion estimate degrades as the magnetic field strength is reduced. The ambient Earth magnetic field increased the final angle error by7.1 during a 90 rotation maneuver when compared to the maximum Helmholtz cage condition.

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Document Details

Document Type
Technical Report
Publication Date
Jun 16, 2016
Accession Number
AD1054252

Entities

People

  • Eric A. Bassett

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Advanced Electronics
  • Sensors
  • Space

DTIC Thesaurus Topics

  • Air Force
  • Computational Science
  • Computer Programming
  • Computers
  • Control Systems
  • Coordinate Systems
  • Gas Bearings
  • Graphical User Interface
  • Magnetic Fields
  • Measurement
  • Operating Systems
  • Performance Tests
  • Spacecraft
  • Test Beds
  • Test Equipment
  • Test Facilities
  • Three Dimensional

Readers

  • Plasma Physics / Magnetohydrodynamics
  • Robotics and Automation.

Technology Areas

  • Space
  • Space - Satellites
  • Space - Spacecraft Maneuvers