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Single gimbal control moment gyros (SGCMG) system cannot afford accurate three axis torque in singular states. A singularity escape method is designed based on the analysis of singularity principle. Firstly, a new dynamic coordinate system is created and switched as the steering reference coordinate system. Secondly, one of the control dimensions is abandoned when the SGCMG system moves into the singular state and the system is considered as a redundant SGCMG control system within a plane. Thirdly, a null motion in the two dimensional space is provided so that the SGCMG can move out of the singular state quickly. Finally，the three dimensional steering law needs to be switched on after the SGCMG system escapes from the singular state. The method's impressive performance on singularity escape is demonstrated by the simulation results. [ABSTRACT FROM AUTHOR]

For the attitude control system of a spacecraft, non-smooth control technique is utilized to improve the robustness and dynamic performance. A continuous attitude control law is given to ensure the homogeneity of the closed-loop attitude control system with a negative degree of homogeneity. The resulting attitude control system is finite-time stable, thus guaranteeing the dynamic performance of state variables. Simulation is carried out under the cases of the nominal system and the systems with parameter uncertainties and external disturbances, respectively. The simulation results show that, under the designed control law, the nominal system is finite-time stable, and uncertain systems are robust against uncertainties and disturbances. [ABSTRACT FROM AUTHOR]