Medium-frequency disturbance attenuation for the spacecraft via virtual-gimbal tilting of the magnetically suspended reaction wheel

A medium-frequency disturbance attenuation strategy based on the virtual-gimbal effect of the active magnetically suspended reaction wheels (MSRWs) is proposed to improve the pointing stability for the high-resolution observation of the spacecraft. The disturbances decreasing the pointing stability include not only the space environment disturbances with low frequency but also the flexible modes and vibrations with medium frequency which are excited by the flexible appendix and the rotating components. The model of the MSRW is constructed firstly and the model of the spacecraft with one MSRW is then developed. Furthermore, a hybrid three-loop control strategy is designed to stabilise the pointing of the spacecraft and the MSRW, where the compensation loop is used to attenuate the medium-frequency disturbances beyond the bandwidth of the attitude control loop. The bandwidth of the MSRW is expanded by tilting the rotor shaft, and the attitude angular velocity is directly feedback to the compensation loop. In addition, the cross feedback control is introduced to attenuate the medium-frequency disturbances. Finally, simulations are constructed and the results indicate the medium-frequency disturbances are effectively attenuated.