CMG Singularity Avoidance in Attitude Control of a Flexible Spacecraft

This paper deals with spacecraft attitude control using an array of 4, single-axis CMGs. This paper investigates a singularity cost function involving a p norm (p = 20 has been shown to be effective). This approach highly weights the CMG closest to singularity, while avoiding the problems encountered with infinity norms and the resulting chatter that occurs when several CMGs have close to equal proximity to a singularity. Cost function sensitivities are calculated analytically to improve performance. Performance is evaluated using a realistic, flexible-body simulation of the ASTREX, space-based mirror.