Abstract: The attitude control problems were investigated for the earth-oriented three-axis stabilized satellite with a SGCMGs system that only two control moment gyros can be utilized for the others’ failures, and a hybrid control method combining 2 SGCMGs with magnet torquers was proposed to overcome the robustness deficiency of the 2-SGCMGs underactuated system. The nominal gimbal angles for the zero-momentum system were derived with the geometric method. On the basis of the nominal SGCMG gimbal configuration, a novel control frame was established to divide the 3dofs torque command space into two orthogonal subspaces, in which the control commands can be implemented with 2 SGCMGs and magnet torquers individually, and the decoupled control was in turn accomplished for the two different type actuators with significance of difference. Moreover, implementation algorithms of CMG gimbal rate commands and magnet torquer dipole moment commands were also presented. Finally, the effectiveness and robustness of the proposed method were demonstrated by the numerical simulation for the satellite dynamics in the presence of space environmental disturbance torques, and high accuracy performances were achieved with the attitude error less than 0.05° and the attitude stability higher than 0.0005°/s, which can satisfy the general application requirements of high resolution earth remote-sensing satellites.

Key words: satellite, attitude control, hybrid control, control moment gyro, magnet torquer, magnetic momentum , dumping