High-accuracy star sensor calibration based on intrinsic and extrinsic parameter decoupling

Abstract

The performance of star sensors largely depends on the accuracy of the model parameter estimation carried out through calibration. Measurement errors in the calibration data would cause estimated values to deviate from the actual values and couple with one another. Only the intrinsic parameters estimated through calibration are useful to star sensors. Thus, the coupling between estimated intrinsic and extrinsic parameters would affect star sensor accuracy. High-accuracy star sensors are significantly affected by such coupling between the aforementioned parameters. This study investigates the coupling between extrinsic and intrinsic parameters through calibration residual and starlight pointing error. A calibration method based on the decoupling of intrinsic and extrinsic parameters is then proposed. The proposed method uses the invariance of intrinsic parameters and estimates intrinsic parameters through simultaneous optimizations with distinct extrinsic parameters. In both the simulations and the experiment, the decoupling calibration effectively improves the accuracy of the intrinsic parameter estimation. Using the same calibration data, the intrinsic parameters’ estimation precision of a high-accuracy star sensor increased by a range from 50.83 to 86.47%.