A steering law of 3 unit control moment gyros for a small satellite

摘要

A steering law for three unit single gimbal Control Moment Gyros (CMGs) is proposed for an attitude control torquer of a small satellite. Though a usual steering law uses its system redundancy to avoid singularity. a three unit system has no redundancy. The proposed law avoids singularity first by finding a non-singular state with the same angular momentum as of the singular state then by changing the state to the nonsingular state. During this change of the state, the attitude control is switched off but the duration is minimal if the change is made by maximum gimbal rate. Also an attitude deviation by this change is made small by maximum rate. An algorithm of the steering law was outlined for two CMG configurations and the performance of this law was examined by numerical simulations.