Abstract
Owing to the vibrations and thermal shocks that arise during the launch and orbit penetration process, the on-orbit installation parameters of multiple star sensors are different from the on-ground measured parameters, causing inconsistencies in the attitude determinations from different combination modes and seriously affecting the geometric accuracy of high-resolution optical remote sensing images. This study presents an on-orbit calibration approach for the installation parameters of a multiple star sensors system using ground control points (GCPs). Based on the on-ground installation parameters of the optical axes of conventional star sensors, a fiducial coordinate system is proposed as the calibration coordinate system. The installation parameters of the conventional star sensors are calibrated using the statistical characteristics of angles between axes of the star sensor and three fiducial vectors in the J2000 celestial coordinate system. Based on the GCPs, the relative fiducial parameters are calculated, and the installation parameter of unconventional star sensor is then calibrated with the relative fiducial parameters and statistical characteristics of angles. It can be used for high-resolution optical remote sensing satellite measuring with only two star sensors to unify the fiducial coordinate system. The proposed method is tested using simulated data and on-orbit measurement data. The results demonstrate that the proposed method can calibrate the optical axis of the star sensor without the restriction of the accuracy of horizontal axis. Moreover, the star sensor with a large installation angle error can be calibrated well using the proposed approach. The results of attitude determinations from different star sensor combination modes are consistent, and the geometric accuracy of the remote sensing images is significantly improved.
Highlights
The geometric accuracy of high-resolution optical remote sensing satellites without ground control points (GCPs) is influenced by factors such as the orbit determination error, attitude determination error, time measurement error, calibration error of the optical camera, and observation conditions [1,2,3]
To improve the geometric accuracy, a high-resolution optical remote sensing satellite is usually equipped with star sensors as the attitude determination system (ADS), owing to its advantages in anti-jamming, resistance to drift with time, and higher measurement accuracy [6,7,8]
Using the statistical characteristics of the angle between the axis of the star sensor and three fiducial vectors in the J2000 celestial coordinate system, the installation parameters of the conventional star sensors are calibrated in the fiducial coordinate system established by the on-ground installation parameters of the optical axes of the conventional star sensors
Summary
The geometric accuracy of high-resolution optical remote sensing satellites without ground control points (GCPs) is influenced by factors such as the orbit determination error, attitude determination error, time measurement error, calibration error of the optical camera, and observation conditions [1,2,3]. The attitude measurement error becomes a key factor influencing the geometric accuracy of high-resolution optical remote sensing satellites without GCPs [5]. To improve the geometric accuracy, a high-resolution optical remote sensing satellite is usually equipped with star sensors as the attitude determination system (ADS), owing to its advantages in anti-jamming, resistance to drift with time, and higher measurement accuracy [6,7,8]. There are usually two star sensors working simultaneously, forming a variety of star sensor combination modes for precise attitude determination These star sensors, which belong to a common combination mode, are denoted as conventional star sensors, i.e., star sensor B and star sensor C. The combined mode with star sensor B and star sensor C is considered as a conventional combined mode, whereas the combined modes with star sensor A and star sensor B or star sensor A and star sensor C are regarded as unconventional combined modes
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