Reconstruction Method of Satellite Gravity Gradient Measurement Angular Velocity by Combining Star Tracker Quaternion

  Objectives  In order to calculate the high precision gravity gradient in level 1b (L1b) data processing of gravity field and steady-state ocean circulation explorer(GOCE)satellite, it is necessary to accurately measure the satellite attitude angular velocity. In the coordinate system transformation of the attitude data of astrology, the low precision angular velocity components of a single astrology instrument will transmit the noise to other angular velocity components, which will affect the calculation accuracy of the whole gravity gradient.

  Methods  In this paper, based on the noise characteristics of the astrological instrument, the weighted matrix of the noise distribution on each axis of the astrological instrument is constructed, and the optimal attitude quaternion is solved jointly for the attitude quaternion of two or more astrological instruments, so as to provide accurate attitude control for subsequent angular velocity recovery.

  Results  Compared with the single astro-meter calculation method, the accuracy of the optimal attitude angular velocity components w_y and w_z obtained by the combination of multiple astro-meters can reach about 1 order of magnitude higher within 10-100 mHz, and the noise level is up to 10^-6 rad/s, which can effectively suppress the noise propagation caused by the low precision angular velocity components in coordinate system transformation.

  Conclusions  The results show that the satellite attitude angular velocity calculated by the combination of multiple astrological instruments can be significantly improved in the whole power spectral density, the power spectral density of gravity gradient trace values calculated by the combined method of multiple astrologers is also significantly improved compared with the single astrologer method.