Autonomous navigation for lunar satellites using celestial objects and landmarks

With the development of our lunar exploration project, the capability of autonomous navigation is in great demand for lunar satellites for limitations of radiometric tracking. A new autonomous navigation method based on celestial and landmark measurements is proposed in this paper. An advanced unscented Kalman filter and corresponding information fusion technique are used to get a better navigation performance and higher reliability. Furthermore, because updated quaternion hardly obeys a unit norm constraint, and Euler angles always exist singular, an advanced Quaternion-generalized Rodrigues attitude estimation approach is proposed. It guarantees both quaternion and quaternion-error within the norm constraint, and provides the adaptive ability to compensate for system errors. Results verify that all navigation information, including position, velocity and attitude are given with a high accuracy. This method is a promising and attractive scheme for autonomous navigation of lunar satellites.