A Study on Singularity of Single Gimbal CMG Systems

Abstract

A single gimbal CMG system is a promising candidate for an actuator of attitude control systems for large space structures. One of its problems is the existence of singular states. Various steering laws assume redundancy in the system and avoid singular states by maximizing a certain criterion function value by a gradient method. But it is not theoretically clear whether these steering laws can avoid all singular states actually. In this paper, a quadratic form is defined for each singular state, which enables to classify singular states into three types. In the vicinity of the two types of singular states, escape from the vicinity is not guaranteed locally. Also it is diffcult to guarantee that the system does not go into the vicinity of any two types of singular points by using the gradient method only. Examples of three type singular states are shown for three configurations.