Singular Direction Escape Steering Law for Control Moment Gyros

Abstract

This paper proposes a new singularity direction escape steering law for control moment gyros (CMG) using singular value decomposition (SVD). The proposed steering law differs from the classical singular direction avoidance (SDA) steering law in two respects. First, torque errors are introduced in the direction of the smallest two singular values through modification of the diagonal matrix. This is done by tuning parameters related to the magnitude of torque error so that both singularity avoidance and escape performance can be achieved. Second, instead of using a conventional singularity measure, new output torque metrics of the CMG cluster along the torque command direction are introduced and adopted in this steering law, so as to reduce unnecessary torque error for certain near-singular circumstances. Several numerical simulations are provided at last, and comparisons with existing steering laws are presented to demonstrate the superior performance of the proposed method.