Hybrid magnetic attitude control gain selection

Abstract

For spacecraft in low Earth orbits, attitude control via the torques provided by the geomagnetic field is an attractive option. Recent research has demonstrated that asymptotic pointing of attitude setpoints is possible using a linear combination of Euler parameter and angular velocity feedback. However, given the time-varying nature of the magnetic field, the size of the gains leading to stability is restricted. The present work looks at a hybrid scheme consisting of magnetic control using on-board dipole moments and an independent three-axis actuation scheme (i.e. reaction wheels or thrusters). A stability analysis is presented using passivity concepts that shows that the limitation on magnetic control gains can be removed if a minimum level of three-axis actuation augments the magnetic scheme.