Spacecraft attitude control using parallel-gimbaled variable speed control moment gyros group

This paper studies the control law for parallelgimbaled variable speed control moment gyros(VSCMG) and it's application in attitude control of a spacecraft.The attitude dynamics equation of a spacecraft with VSCMG and a globally asymptotical stable attitude feedback control law is firstly presented.A pair of parallelgimbaled VSCMG is controlled as one separate unit and a rotational coordinate is introduced.Furthermore,a control law for CMGs is presented,it makes the CMGs controllable in singularity configuration,and the torque error keeps zero in one axis of the rotational coordinate.The parallelgimbaled configuration and the variable speed of rotors are used to compensate for the torque error of the CMGs to make the torque produced by VSCMG equivalent to the required torque.Finally,the numerical simulation of the attitude control of a spacecraft is implemented on the sample of a double parallelgimbaled VSCMG.A control torque distribution scheme is presented in the simulation,and the simulation results demonstrate the proposed control law to be valid.