Nanosatellite Three-Axis Attitude Control and Determination Using Two Magnetorquers Only

The paper considers two magnetorquers as the sole attitude control system unit used both for control and determination. An algorithm of the three-axis attitude determination is proposed. It utilizes the measurements of the electromotive force induced in magnetorquers during the free motion of the satellite when the control is not applied. The extended Kalman filter is used. The estimation of the state vector consisting of the vector part of quaternion and the angular velocity vector is used for the control calculation. Three axis attitude is achieved with the same magnetorquers using the Lyapunov control approach. The paper studies the accuracy of the developed algorithm, its dependence on orbit inclination and orbit altitude.