Analysis and precision attitude control using control moment gyro for rapid multi-target observation

Control moment gyros (CMGs) are used for the precision attitude control for their torque amplification capability recent years. Precisely and stable pointing accuracy is very crucial of Nano-satellite for required missions. In order to perform slew maneuvers between the continuous targets, this paper used four CMGs to perform a pyramid structure and compared two useful robust attitude control algorithms (sliding mode control method and high order sliding mode control method). However, the singularity problem inherent CMGs is inevitable during the design period. The pseudo-inverse steering logic that based on mixed two-norm and least-squares minimization is chosen which can deal with both the internal singularity problem and momentum saturation singularities if the steering resolution factors are properly selected. This attitude control system was verified through numerical simulation. And the results demonstrate the validity and feasibility of the proposed approach.