Spacecraft Attitude Control Using a Double-Gimbal Control Moment Gyro

This paper presents a novel attitude control scheme for a spacecraft. It involves the use of a double-gimbal control moment gyro (CMG), wherein the rotational speed of the momentum wheel is kept constant. Tilting the spin axis of the momentum wheel around either an inner or an outer gimbal axis can generate attitude control torques in one rotational direction. In order to compensate for the absence of control torque in the other rotational direction, a combination of rotations of the inner and outer axes is designed to generate a cyclic motion about the spin axis of the momentum wheel resulting in three-axis attitude control. Analytical and numerical algorithms are developed to compute the control inputs, i.e., the tilt angles of the inner and outer gimbal axes, which are responsible for the desired change in attitude. The effectiveness of the proposed control scheme is verified by numerical simulations.