Imaging type method for correcting earth oblateness by earth sensor

Abstract

The invention discloses an imaging type method for correcting earth oblateness by an earth sensor, which comprises the following steps: extracting a coordinate of an image point of an earth contour point on a photoelectric detector of the sensor and computing a unit vector of the image point in a spacecraft system; assuming the earth is a standard sphere, computing a geocentric vector VEB, and acquiring a rolling angle and a pitch angle Theta of the spacecraft according to the geocentric vector VEB; estimating a yaw angle Psi of the spacecraft at the current moment according to the posture ofthe spacecraft at previous moment, simultaneously acquiring a current position and a coordinate system transformation matrix of the spacecraft from a spacecraft posture orbit control system, and computing an azimuth angle Sigma of the earth contour point; computing corresponding viewing angle radius Eta according to the azimuth angle Sigma of the earth contour point; and finally, using the viewing angle radius Eta of the earth contour point to remove the influence on the earth oblateness, and acquiring the corrected geocentric vector. The method has simple operation, and can provide more accurate geocentric vector.

Description

technical field [0001] The invention relates to a method for correcting the oblateness of the earth when a space-borne earth sensor is imaging, which can be used to improve the measurement accuracy of the sensor. Background technique [0002] The earth sensor can determine the roll and pitch attitude of the spacecraft through the measurement of the geocentric vector; the combination of the geocentric vector and other celestial vectors (such as star vectors) can also determine the velocity and position of the spacecraft, so the earth sensor is Indispensable for future spacecraft attitude and orbit control systems. [0003] The earth sensor is composed of optical head, sensor and signal processing, and some also include mechanical scanning components. According to whether it contains mechanical scanning components, it can be divided into dynamic scanning type and static imaging type. The dynamic scanning earth sensor uses moving mechanical parts to drive one or more fields o...

AI Technical Summary

Problems solved by technology

However, since the moon is a standard spherical shape, there is no oblateness problem, so when the vector method in this paper is applied to the calculation of the geocentric vector, although the calculated value of the geocentric vector can be obtained, its accuracy is greatly affected

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