LAUSR

Abstract Gyro-less angular velocity estimation is significant for the attitude control of spacecraft when the gyro is unavailable. The paper considered that the angular velocity remains almost constant in a short free-motion period, indicating that these endpoints of celestial body directions are on parallel planes. On this basis, we developed a novel angular velocity estimation method by optimizing these parallel planes with an iterative algorithm. Moreover, we proposed an alternative intermittent attitude control method, including a free-motion period for angular velocity calculation and a control period for attitude stabilization, respectively. Wherein, the length of the free-motion period is adjusted according to the magnitude of angular velocity to improve the calculation accuracy. Besides, we introduced a control law and analyzed the system stability using the Lyapunov method. For validation, we developed some simulation cases by constructing a semi-physical simulation platform and analyzed the effects of observation noise, the moment of inertia, and angular velocity. The simulation results show that the angular velocity estimation method has better accuracy and faster convergence than the Kalman method when considering observation noise. That is, the proposed intermittent attitude control method is feasible for the attitude stabilization.