Abstract: The performances of the extended Kalman filter (EKF), unscented Kalman filter and squareroot Kalman filters (SREKF, SRUKF) for relative navigation based on lineofsightonly measurement in spacecraft rendezvous operation are compared. The characteristics of the proposed relative navigation and the algorithms for the above four Kalman filters are introduced. The relative dynamic models of the chaser and the target spacecraft as well as the measurement model of the lineofsightonly relative navigation are established. Numerical simulations are undertaken for three typical relative motions. The simulation results show that the accuracies of the relative navigation based on lineofsightonly measurement via the four filtering algorithms (EKF, UKF, SREKF, and SRUKF) are at the same level. The UKF performs a little better than the EKF, and the SREKF and SRUKF perform a little better than the EKF and UKF on the accuracy of the relative distance.

Key words: relative navigation, lineofsight measurement, Kalman filter, relative distance