Session
Technical Session III: Advanced Technologies I
Abstract
The Satellite Design Laboratory at the University of Texas at Austin is building a general purpose guidance, navigation, and control (GN&C) module with 6 degree-of-freedom maneuver capability. The GN&C module is capable of meeting multiple pointing constraints autonomously utilizing new constrained attitude control algorithms. Attitude keep-out zones are avoided by first discretizing the unit sphere into a graph using an icosahedron-based pixelization subroutine. An admissible path is found using the A* pathfinding algorithm. The trajectory is followed by a rate and torque constrained quaternion feedback controller. The algorithm is capable of running in real-time on a low power embedded flight computer. The module has secured flight opportunities on two student-built 3U CubeSats for flight projects sponsored by the Air Force and NASA. Both sets of mission requirements are satisfied with the same 3U CubeSat attitude control system, demonstrating the algorithm’s versatility as a general purpose controller. The autonomy provided by the advanced constrained control algorithms enables more complex picosatellite missions and decreases the cost of spacecraft subsystems by shifting requirements away from the hardware and onto the control algorithm.
Presentation Slides
A Constrained Attitude Control Module for Small Satellites
The Satellite Design Laboratory at the University of Texas at Austin is building a general purpose guidance, navigation, and control (GN&C) module with 6 degree-of-freedom maneuver capability. The GN&C module is capable of meeting multiple pointing constraints autonomously utilizing new constrained attitude control algorithms. Attitude keep-out zones are avoided by first discretizing the unit sphere into a graph using an icosahedron-based pixelization subroutine. An admissible path is found using the A* pathfinding algorithm. The trajectory is followed by a rate and torque constrained quaternion feedback controller. The algorithm is capable of running in real-time on a low power embedded flight computer. The module has secured flight opportunities on two student-built 3U CubeSats for flight projects sponsored by the Air Force and NASA. Both sets of mission requirements are satisfied with the same 3U CubeSat attitude control system, demonstrating the algorithm’s versatility as a general purpose controller. The autonomy provided by the advanced constrained control algorithms enables more complex picosatellite missions and decreases the cost of spacecraft subsystems by shifting requirements away from the hardware and onto the control algorithm.
