Non-Dimensional Star-Identification.

Carl Leake,David Arnas,Daniele Mortari

doi:10.3390/s20092697

Abstract

This study introduces a new “Non-Dimensional” star identification algorithm to reliably identify the stars observed by a wide field-of-view star tracker when the focal length and optical axis offset values are known with poor accuracy. This algorithm is particularly suited to complement nominal lost-in-space algorithms, which may identify stars incorrectly when the focal length and/or optical axis offset deviate from their nominal operational ranges. These deviations may be caused, for example, by launch vibrations or thermal variations in orbit. The algorithm performance is compared in terms of accuracy, speed, and robustness to the Pyramid algorithm. These comparisons highlight the clear advantages that a combined approach of these methodologies provides.

Highlights

IntroductionAlgorithm can be used to identify stars using only the observed directions of the unknown stars and the on-board star catalog
If a star tracker is working as intended, a nominal lost-in-space star identification (Star-ID)algorithm can be used to identify stars using only the observed directions of the unknown stars and the on-board star catalog
When the nominal lost-in-space algorithm fails due to perturbations of the focal length and/or the optical axis (OA) offset in the star tracker, the non-dimensional Star-ID algorithm (NDSIA) is still able to identify stars

Summary

Introduction

Algorithm can be used to identify stars using only the observed directions of the unknown stars and the on-board star catalog. These algorithms are paramount for determining the attitude of a spacecraft using a star tracker. In terms of speed and robustness, the state-of-the-art algorithm to identify stars in the nominal lost-in-space scenario is the nominal lost-in-space algorithm Pyramid [1]. The Pyramid algorithm recognizes observed stars using the invariance of the angles between observed and cataloged stars. The k-vector range searching technique [2,3] is the internal engine of Pyramid that facilitates a quick and robust Star-ID. The Pyramid algorithm is summarized in Appendix B

Objectives

Results

Conclusion