Attitude control system for a three-axis stabilized satellite especially

Abstract

An attitude control device for a three-axis stabilized satellite in terrestrial orbit embodies an attitude sensing system adapted to deliver roll, yaw and pitch attitude signals, a set of at least three non-parallel axis momentum wheels and a set of at least two magnetic coils oriented at least approximately in two non-parallel directions in the roll/yaw plane. A primary control loop embodies a processor and controller connected between the attitude sensing system and the set of at least three momentum wheels. It is adapted to determine from attitude signals and attitude set point signals attitude correction signals for the momentum wheels so as to apply to the satellite primary attitude correction torques. A secondary control loop embodies a coil controller connected between the processor and controller, the set of at least three momentum wheels and the set of at least two magnetic coils. It is adapted to determine from attitude correction signals addressed to the momentum wheels and from signals representative of the behavior of the wheels compensation signals to be applied to the magnetic coils so that by interaction with the terrestrial magnetic field secondary attitude correction torques are applied to the satellite. A circuit for desaturation in pitch of the set of at least three momentum wheels is connected between the set of at least three momentum wheels and a pitch actuator.