MPC for coupled station keeping, attitude control, and momentum management of low-thrust geostationary satellites

Abstract

This paper develops a model predictive control (MPC) policy for simultaneous station keeping, attitude control, and momentum management of a nadir-pointing geostationary satellite equipped with three reaction wheels and four gimbaled electric thrusters that are located on the anti-nadir face of the satellite. The MPC policy works in combination with an inner-loop SO(3)-based attitude controller that ensures the satellite maintains a nadir-pointing attitude. The MPC policy is able to maintain the satellite's position within a prescribed latitude and longitude window, while minimizing the Δv required by the thrusters. The MPC policy also enforces thruster pointing constraints and manages the satellite's stored momentum. With reference to simulation results, we explain how the MPC is tuned for station keeping, the need for an inner-loop attitude controller, and how these separate systems work together to achieve all the controller's objectives.