Unscented kalman filter for multiple spacecraft formation flying
Lingji Chen, S. Seereeram, R.К. Mehra · 2004
Abstract In this paper, Unscented Kalman Filter (UKF) is presented both in its canonical form and in a form that is suitable for spacecraft attitude estimation using quaternions. An atti- tude quaternion has a unit norm, resulting in a singular co- variance matrix. Techniques have been developed in the past to deal with this problem, in the context of Extended Kalman Filter (EKF), and the current paper presents the counterpart in the context of UKF. Simulation studies con- firm that at low noise level, EKF and UKF behave in essen- tially the same way, while at high noise level, UKF is more accurate and robust. For multiple-spacecraft formation fly- ing, robustness with respect to noise level and choice of co- ordinate frame is highly desirable, hence it is argued that UKF is better suited for the task than EKF, especially in view of the fact that the additional computational cost asso- ciated with UKF is not significant. 1 Introduction Relative state estimation is an integral part of any forma- tion flying mission. One way of solving the nonlinear es- timation problem is by using the Extended Kalman Filter