On Disturbance Rejection for Gimbal Servo System of Flexible Mounting Control Moment Gyroscope

Harmonic disturbance is the main form of disturbances in control moment gyroscope (CMG) gimbal servo system. Also, flexible vibration isolation platform inevitably introduces unmodeled dynamics to the gimbal servo system. These disturbances and dynamics destroy the performance of the CMG gimbal servo system. However, few studies on flexible mounting dynamics have been proposed. In this paper, the model of flexible mounting dynamics is built firstly. Then, this paper designs compensation controllers in the speed loop and current loop which can completely compensate the speed attenuation oscillation of gimbal servo system caused by flexible mounting dynamics. Based on these, a harmonic disturbance observer (HDOB) is designed to compensate harmonic disturbance. It has better observation effect than general disturbance observer (DOB). The entire composite controller is designed under the frequency domain. The simulation results show the superiority of the control performance.