Managing Unwinding in Quaternion-Based Anti-Windup Compensation for Constrained Rigid Body Attitude Control

This paper investigates the problem of unwinding in quaternion-based anti-windup compensation for constrained rigid body attitude control. Quaternion-based compensators and controllers can lead to the unwinding phenomenon if the double covering problem of the rigid-body-attitude space is not considered. Moreover, actuator saturation is a source of performance degradation or even instability of control systems. Therefore, in this paper, a quaternion-based anti-windup compensator is proposed and stability proofs are derived that provide asymptotic stability properties and a propensity to avoid attitude unwinding. Simulation results illustrate that the proposed method leads to significantly smaller rotation of the rigid body than an earlier anti-windup approach which does not address the unwinding phenomenon.