Sun-Pointing Attitude Control Scheme for Magnetic-based Satellite

Abstract

For some low-orbit satellites, SADA (solar array drive assembly) is not necessary but steady sun-pointing is required. Magnetic-based attitude control schemes are adopted by more and more low-cost low-orbit satellites and magnetic-based sunpointing attitude control schemes have been proposed for various satellites. For magnetic Attitude Determination and Control System (ADCS), magnetometer and magnetic torquer are the core ADCS components while sun sensor and gyro, which would be employed to determine or estimate sun vector, are important ones. Due to the underactuated characteristics, magnetic attitude control torque could not stabilize the full attitude but the two components of the attitude, simultaneously, which means that magnetic attitude control effort could orientate the solar panels to the Sun. A Lyapunov function, combining the rotational energy and sun angle, is formulated and a PD-type sun-pointing attitude control scheme is proposed to meet the requirements corresponding to sun-pointing task. Further, the effectiveness of the PD-type sun angle-based magnetic attitude control scheme, composed of proportional term, damping term and spinning term, has been verified by use of Lyapunov direct method. Simulations show that, the proposed PD-type attitude control scheme is a suitable sun-pointing scheme for magnetic satellites.