Abstract
Abstract. On space remote sensing stereo mapping field, the angle variation between the star sensor’s optical axis and the earth observation camera’s optical axis on-orbit affects the positioning accuracy, when optical mapping is without ground control points (GCPs). This work analyses the formation factors and elimination methods for both the star sensor’s error and the angles error between the star sensor’s optical axis and the earth observation camera’s optical axis. Based on that, to improve the low attitude stability and long calibration time necessary of current satellite cameras, a method is then proposed for real-time on-orbit calibration of the angles between star sensor’s optical axis and the earth observation camera’s optical axis based on the principle of auto-collimation. This method is experimentally verified to realize real-time on-orbit autonomous calibration of the angles between the star sensor’s optical axis and the earth observation camera’s optical axis.
Highlights
Exterior orientation elements are a key factor influencing the positioning accuracy, when performing satellite photogrammetry without ground control points (GCPs) (Wang, 2004)
The method can be realized on the optical mapping satellite on-orbit by installing an optical autocollimator inside the star sensor and earth observation camera optical systems
The change of the main optical axis of each camera can be reflected by the change of the spot image position, using the original optical path of the camera
Summary
Exterior orientation elements are a key factor influencing the positioning accuracy, when performing satellite photogrammetry without ground control points (GCPs) (Wang, 2004). The accuracy of the exterior orientation elements is affected by systematic or random errors in both the star sensor and the angles between the star sensor’s optical axis and the earth observation camera’s optical axis contain, caused by various on-orbit factors, such as pressure, vibration and temperature. Based on previous research results and a large amount of measured data we’ve accumulated in the long-term, the paper analyses the measurement error and on-orbit calibration results of the star sensor, and finds that the thermo elastic error is the main factor to cause the angle variation between the star sensor’s optical axis and the earth observation camera’s optical axis, which limits the positioning accuracy. We calculate the angular variation between the star sensor’s optical axis and the earth observation camera’s optical axis, allowing for real-time calibration on the satellite
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