INS/CNS navigation system based on multi-star pseudo measurements

Abstract

In the integrated navigation of Inertial Navigation Systems (INS) and Celestial Navigation Systems (CNS), small stellar angular distances in a single field-of-view (FOV) star sensor lead to inaccurate navigation parameter estimations. A novel, INS/CNS integrated navigation system based on multi-star pseudo measurements is proposed in this paper. First, according to the identified navigation star's observation information, five candidate stars are directly selected from the Smithsonian Astrophysical Observatory (SAO) star catalog as those most favorable for estimating the probe position. Then, in addition to the identified navigation star's measurement, the five candidate stars' pseudo observation information are estimated to supplement the measurements. Finally, the INS/CNS integrated navigation system in the tightly coupled mode estimates the probe position with high accuracy utilizing the available measurement and pseudo measurements. The simulation results illustrate that, compared to the traditional INS/CNS integrated navigation system which uses the infrared Earth sensor to assist in measuring the celestial measurements of navigation stars in the star image, and the improved method which directly supplements the position measurement by the infrared Earth sensor, the proposed method markedly improves the positioning accuracy, while the three methods' total computational efficiencies including measurement acquisition and filtering are effectively the same.