Three-Axis Satellite Attitude Control Based on Magnetic Torquing - Linear Optimal Approach

Abstract

Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvement of micro-electronics. This paper discusses an attitude controller for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. Magnetic torquing is cheap, lightweight, and power efficient. The actuation principle is to use the interaction between the Earth’s magnetic field and the magnetic field generated by the coils. Design of the attitude controller is based on linear approach since the satellite trajectory remains in a neighbourhood of a reference, due to influence of conservative forces of the gravity gradient and the gyro-effect owing to rotation of the satellite around the Earth. Limited computer capacity and restrictions on power consumption demand computational simplicity and power optimality of the attitude control system. Design of a quasi optimal attitude controller with time varying gain for an earth pointing satellite is a subject of considerations in this paper.