The Singularity Avoidance Analysis and Designed Steering Law for VSCMG

Single Gimbal Control Momentum Gyroscopes (SGCMG) have many advantages over other ac-tuators for attitude control system of a spacecraft. The singularity is main obstacle for successfully per-forming the task of the attitude control of the SGCMG. The singularity can be effectively avoided by the additional variable flywheel speed of the Variable Speed Control Moment Gyros (VSCMG) without con-sidering about amplitude of the flywheel torque. In the process of the practical application, lower spin rate of the flywheel are unrealistic for performing gyroscopic torque amplification. Furthermore, the gyroscopic torque cannot be output when the lower bound of the flywheel speed approaching to zero. Consequently, the flywheel speed of VSCMG should have upper and lower bound. In this paper, the singularity character-istics of VSCMG are further analyzed. Furthermore, the torque requirement of the flywheels is analyzed for the steering law of the weighted pseudo-inverse and weighted pseudo-inverse with null motion based on geometry method. Compare with the steering law of weighted pseudo-inverse, the torque requirement of the flywheel will be increased by adding null motion for singularity avoidance. Later, the new steering law is redesigned to overcome the following problems, one is that the saturation problem of flywheel, which is caused by the range of the flywheel regulation speed can be avoided by balancing flywheel regulation speed. two is that the consume power of the flywheel can be reduced.