Modeling of Axial Drift of a Single Gimbal Control Moment Gyroscope

A single gimbal control moment gyroscope (SGCMG) suffers from drift of the gimbal axis. The drift of the gimbal axis results in the null motion of SGCMG, and eventually it causes the instability of the SGCMG-embedded system. Therefore, in this paper, an axial drift of a single gimbal control moment gyroscope (SGCMG) is studied and identified through an extensive empirical process of investigating the relationship between input torques and output angles. It is found that the axial drift can be modeled as a nonlinear sigmoidal function that mimics the sliding mode function for friction models that consist of viscous friction and Coulomb friction approximately. Experimental studies are conducted to confirm the modeling performance of the gimbal axis.