An analysis of characteristics of the satellite autonomous optical navigation system

Abstract

The autonomous navigation system characteristics are investigated for an artificial satellite around a planet. Navigation is based on the optical scanning of stars near the planet's horizon. The recognition of stars and the measurement of angles of star elevation above the horizon are carried out. The subsequent statistical processing of the measurements allows one to determine the satellite's orbital elements with an accuracy dependent on the measurement accuracy and procedure. The analysis employs an exact numerical algorithm and approximate numerical-analytical technique. The navigational accuracies are studied in relation to independent and correlated measurement errors. Comparison is made for navigational accuracies determined by the above two methods. It shows that the approximate technique allows rather well (with an error less than 10%) to find navigational errors even at a small number (3–6) of times of measurements per revolution. When this number is increased the methodical error of the approximate technique quickly diminishes. The navigational accuracies are obtained for the satellite in an orbit with altitude of 300 to 36,000 km. The navigational algorithm was tested in direct numerical simulation and its convergence bounds were determined. The latter show admissible deviations of initial values in orbital elements from the exact ones. The analysis shows that the algorithm is stable at rather large errors in giving the elements of initial approximation.