Spacecraft angular velocity trajectory planning for SGCMG singularity avoidance

A trajectory planning method for angular velocity of spacecraft is developed to avoid the impassable singular states for singular gimbal control moment gyroscope (SGCMG) systems in this paper. A new set of attitude parameters, named σ-parameters, is first developed. Based on the properties of σ-parameters, two approximate decoupled rotations are presented. To achieve a rapid attitude maneuver, both of the decoupled motions are designed as simple bang-off-bang type maneuvers. Then, a type of SGCMG singularity-free angular velocity trajectory on the conic surface is developed. Thereafter, an attitude controller based on σ-parameters is developed to track the reference trajectory. To avoid the impassable singular state, suitable axes of the approximate decoupled two rotations are chosen to achieve the fastest maneuver under the condition that the minimum distance from the angular momentum trajectory to the impassable surface is greater than a safety distance. Finally, simulations are performed to verify the effectiveness of the proposed SGCMG singularity avoidance method.