Spacecraft Attitude Control with Three of Four CMGs in a Pyramid-type Arrangement

Abstract

This paper addresses the steering law for a control moment gyro(CMG) system with only three units using an inverse kinematics logic. A CMG system, which usually consists of four or more CMG units for redundancy, is required accurate attitude control even when one of the CMG units stops its function. In this paper, a suitable steering law for such the CMG system with only three units is proposed. In order to utilize the full angular momentum workspace of the CMG system, we propose the control method with the inverse kinematics logic, instead of derivation of the inverse of the Jacobian matrix. The proposed method is evaluated with numerical simulations and hardware experiments, and is concluded effective for such the CMG system with one failure.