A method for calculating the d-coordinate of the intersection of the optical axis and the celestial sphere based on a star sensor

Abstract

The invention relates to a method for calculating coordinates of an intersection point D of an optical axis and a celestial surface based on a star sensor. The method comprises the steps of establishing a space rectangular coordinate system under a celestial coordinate system, performing translation or rotation transformation on the space rectangular coordinate system to enable the space rectangular coordinate system to coincide with a star sensor coordinate system to obtain a transformation relationship between the two coordinate systems, and representing a coordinate expression of the pointD in the celestial coordinate system by using each parameter; obtaining the relationship among the coordinates according to the cosine law, and obtaining an approximate expression of the distance f from the projection center to the projection point on the star sensor light-sensitive surface by using a Taylor expansion formula; substituting the approximate expression into the coordinate expressionof the point D in the celestial coordinate system to obtain a celestial coordinate approximate value expression of the point D; performing error analysis in combination with a median theorem, and obtaining a fixed star selection standard to further improve the coordinate precision of the point D. The invention aims to establish a mathematical model, solve the coordinates of the intersection pointD of the optical axis and the celestial surface, enables coordinates of the point D to be accurate through an optimization algorithm, and improve the attitude measurement precision of the star sensor.

Description

technical field [0001] The invention relates to the field of celestial navigation, in particular to a calculation method based on the D coordinate of the intersection point of the optical axis of a star sensor and the celestial sphere. Background technique [0002] Celestial navigation is based on the natural celestial body with known accurate spatial position, and realizes the autonomous attitude measurement of the vehicle through the star sensor. The attitude here refers to the orientation element of the image space coordinate system of the vehicle in a given reference system. In this way, the navigation information of the carrier where the measurement point is determined is calculated. Since the star sensor uses the astronomical information of the stars, it has the characteristics of good autonomy, high precision, and reliable operation, and has broad application prospects in spaceflight. At present, the star sensor has been able to achieve completely autonomous attitude...

AI Technical Summary

Problems solved by technology

The advantage of the deterministic method is that it does not require a priori attitude information, but it is difficult to overcome various errors of the reference vector, such as the measurement error, offset error, and installation error of the star sensor, and it is difficult to establish the attitude determination mode and weighting of the aircraft body. Handling Measurements with Different Accuracy

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