An approach to magnetic torque attitude control of satellites via 'H/sub /spl infin//' control for LTV systems

Abstract

A new approach to the three-axis attitude control of satellites using magnetic torque rods is detailed in this paper. The system is under-actuated, as the magnetic torque rods cannot apply torque in a direction parallel to the Earth's magnetic field. However for orbits inclined to the Earth's magnetic equator, the direction of the field vector changes and this fact can be used to design controllers for the system. An extension of the H/sub /spl infin// control technique to LTV systems is used to design periodic controllers for the periodic system. The resulting controllers are simulated on the full non-linear system. The stability and accuracy of the closed-loop system, to less than a degree of pointing error, is demonstrated in the presence of disturbances including gravity-gradient torques, drag torques, and solar radiation pressure torques.