Patent ID: 6523786
Filing Date: 2003-02-25
Classification: B64G

Abstract:
An apparatus for determining the attitude of an artificial satellite comprising:at least one star sensor; a star catalog data base in which information on each of stars in an inertial coordinate system is stored; a star identification section in which star images output from the star sensor are collated with a star catalog in the star catalog data base, with respect to each star sensor, and which outputs a group of corresponding star image candidates; an attitude computation section computing a value of an attitude candidate of the artificial satellite with respect to each corresponding star image candidate; an attitude candidate unification section comparing the values of the attitude candidates, recognizing attitude candidates that agree within a tolerance, thereby indicating correct attitude candidates, and unifying the attitude candidates that agree within the tolerance into a single attitude candidate indicating correct attitude of the artificial satellite; an attitude updating section directly communicating with the star sensor and the attitude candidate unification section and updating the value of each attitude candidate based on star images output from the star sensor and the star catalog; and an attitude propagation section for computing the value of an attitude candidate at a present sampling time from the value of the corresponding attitude candidate at a preceding sampling time and angular velocity of the artificial satellite, wherein the attitude candidate unification section, the attitude updating section, and the attitude propagation section are connected in a processing loop for reducing number of attitude candidates compared to obtain the correct attitude of the artificial satellite.