Abstract:

The core idea of inertial/celestial integrated navigation sytem composed of SINS and star tracker is to estimate and correct SINS navigation errors through a designed kalman filter by use of star’s accurate angle information measured by the star tracker. In this way, divergence of navigation errors along with time could be restricted , and thus navigation accuracy during long time flight could be improved significantly. Based on analysis of the relationship between star tracker’s measurement and SINS’s navigation errors, two integrated navigation algorithms called position plus azimuth correction algorithm and angle error integrated navigation correction algorithm are designed for the system Then, navigation accuracies of the two algorithms are analysed theoretically and validated by using a series of long time flight simulations. The results show that position plus azimuth correction algorithm not disturbed by initial position errors is more suitable when star tracker works intermittently; while angle error integration algorithm which doesn’t disturbed by initial attitude errors is more suitable when SINS’s initial position errors are small or corrected effectively before intergation.

Key words: SINS, Star tracker, Inertial/celestial integrated navigation, Position plus azimuth correcting algorithm, Angle err integration algorithm.