Passability and a Steering Law in Singular States of Control Moment Gyros

Abstract

Singularity is a problem in attitude control of a spacecraft using control moment gyros (CMGs). In this study, the internal singular states of two six-CMG systems; the hexagonal and twin-triangular type CMGs are investigated and one of the CMG arrangement types; the twin triangular type is proven to have only passable internal singular states. By using the passability, the gimbal angle calculation that satisfies the given angular momentum of CMGs is proposed and its effectiveness is compared with an existing method. A steering law for the gimbal angular velocities based on the gimbal angle calculation is also constructed. The attitude control of the spacecraft by using the proposed steering law is examined through numerical simulations.