Singularity-robust control moment gyro allocation strategy for spacecraft attitude control in the presence of disturbances

Abstract

In this paper, a disturbance and singularity robust steering law for a set of single gimbal control moment gyros (SGCMGs) is addressed to improve the agile rotational maneuverability of spacecraft. A roof array is selected and investigated in this work because of the simplicity of the singularity envelope. Also, a feasible angular momentum chart, which provides a singularity-free bound for the roof array, is utilized. It is very important to recover the momentum vector to the initial gimbal direction to overcome the singularity problem. Thus, an optimization technique is described to restore the gimbal vectors back to their original angular position after the rest-to-rest attitude reorientation. Another issue to be examined is that external disturbances interrupt the gimbal vector going back to the initial position. Therefore, a robust allocation logic based on the optimization technique is exploited to handle the effect of external disturbances adequately by using a magnetic torquer. Finally, several numerical simulations are performed to highlight that the allocation logics proposed can overcome the singularity problem and be operated reliably for the spacecraft installed with a roof array of CMGs generating the control torque required for all time exactly.