Control moment Gyro gimble motor ultra-low velocity control system design with direct-drive PMSM

The advent of a Control Moment Gyro (CMG) system has a significant impact on the valid powerful torque output for a three axis attitude control of a spacecraft. The accurate torque of CMG output is mainly determined by the fluctuation of velocity of gimbal servo motor. In this paper, in order to achieve precise position of gimbal absolute position, the dual-channel rotating transformer is select. A velocity measurement method couple thick channel with thin channel is proposed. The feedback calibration of phase is proposed, which can great reduce nonlinear effect and weaken the parameter sensitive of gimbal servo system. The experiment results show that the velocity ratio can achieve 1:30000, and the lowest velocity can reach 1/10000rad/s.