A Comprehensive Calibration Method for a Star Tracker and Gyroscope Units Integrated System

Abstract

The integration of a star tracker and gyroscope units (GUs) can take full advantage of the benefits of each, and provide continuous and accurate attitude information with a high update rate. The systematic error calibration of the integrated system is a crucial step to guarantee its attitude accuracy. In this paper, a comprehensive calibration method for the star tracker and GUs integrated system is proposed from a global perspective. Firstly, the observation model of the predicted star centroid error (PSCE) with respect to the systematic errors including the star tracker intrinsic parameter errors, GUs errors and fixed angle errors is accurately established. Then, the systematic errors are modeled by a series of differential equations, based on which the state-space model is established. Finally, the systematic errors are decoupled and estimated by a Kalman filter according to the established state-space model and observation model. The coupling between the errors of the principal point and subcomponents of the fixed angles (i.e., normalΨx and normalΨy) is analysed. Both simulations and experiments indicate that the proposed method is effective at estimating the systematic errors of the star tracker and GUs integrated system with high accuracy and robustness with respect to different star centroid accuracies and gyroscope noise levels.

Neural Network Calibration of Star Trackers

“…Unlike many terrestrial calibration applications, our goal is to predict star direction vectors with minimal angular error; reconstructing full 3D world-vectors is of limited utility. Additionally, compatibility with on-orbit autonomous recalibration methods [18], [19], [20] is also important. Thus, while the absolute orientation of the sensor is known during ground calibration, the relative geometry between stars is the only truth measure available for on-orbit studies.…”

Installation angle calibration between the star sensor and gyro unit using the equivalent rotation vector transformation

“…There are few reports on the calibration of installation angles between the star sensor and GU. In [16], a comprehensive calibration method was proposed based on the difference between predicted and observed star centroids. To calibrate system errors and increase observability in the filtering method, additional measurements are required.…”

A High-Accuracy Star Centroid Extraction Method Based on Kalman Filter for Multi-Exposure Imaging Star Sensors

“…However, the attitude update rate (AUR) of the traditional star sensor is usually 4–10 Hz, which is too low to accomplish navigation tasks independently. In order to improve the AUR, an integrated navigation system of a star sensor and inertial measurement unit (IMU) has become a kind of classic solution [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. The attitude data of the star sensor have no drift but the update rate is low, while the update rate of the IMU is high, but the attitude data drift with time.…”