Session
Poster Session 1
Abstract
This work presents 3 candidate strategies for all-magnetic attitude control of a 3U CubeSat using a magnetometer and sun sensors for attitude determination. The study focuses on the sun-acquisition problem and does not treat rate damping (detumbling). The first method is a ‘naïve’ 3-Axis position control applying torques on each axis depending on the attitude error angle on that axis. This method is well known to yield poor results, but provides a theoretical footing for the rest of the work. The second method takes specificities of actuators and the sun-acquisition problem into account to tailor a better controller. Since the Sun acquisition is a 2-axis positioning problem, this method particularizes the previous one, leaving the pointed axis uncontrolled in rotation. Safeguards are foreseen to avoid velocity build-up on the uncontrolled axis. The last method uses a 2-phases strategy to spin the satellite and provide gyroscopic stiffness before pointing the spun axis towards the sun. The momentum is directed in such a way that if the satellite is perfectly pointed, the momentum is collinear to the target direction. After presenting these 3 strategies, their performances in the simulation environment of CNES are analyzed in terms of pointing accuracy and convergence time.
A Comparative Analysis of All-Magnetic Attitude Control Techniques for Nanosatellites Sun Acquisition
This work presents 3 candidate strategies for all-magnetic attitude control of a 3U CubeSat using a magnetometer and sun sensors for attitude determination. The study focuses on the sun-acquisition problem and does not treat rate damping (detumbling). The first method is a ‘naïve’ 3-Axis position control applying torques on each axis depending on the attitude error angle on that axis. This method is well known to yield poor results, but provides a theoretical footing for the rest of the work. The second method takes specificities of actuators and the sun-acquisition problem into account to tailor a better controller. Since the Sun acquisition is a 2-axis positioning problem, this method particularizes the previous one, leaving the pointed axis uncontrolled in rotation. Safeguards are foreseen to avoid velocity build-up on the uncontrolled axis. The last method uses a 2-phases strategy to spin the satellite and provide gyroscopic stiffness before pointing the spun axis towards the sun. The momentum is directed in such a way that if the satellite is perfectly pointed, the momentum is collinear to the target direction. After presenting these 3 strategies, their performances in the simulation environment of CNES are analyzed in terms of pointing accuracy and convergence time.
