Error Analysis And Calibration In Starsensor Application

To solve the analysis and calibration problem of star sensor’s measurement error, this paper builds several measurement error models of star sensor and conducts these errors’ on-orbit calibration. This paper also analyzes the effect of these errors on star sensor’s performance, and the main contents are listed as below.At first, this paper researches on the effect of space environment on star sensor’s performance. The effects of plasma, high-energy particle, space radiation, thermal vacuum, elemental oxygen and contaminated environment are researched individually. This paper indicates that the space environment causes several measurement errors of star sensor, such as lens’ thermal distortion and image plane displacement.Furthermore, this paper researches on the thermal distortion of star sensor lens. The thermal distortion model based on starlight vector calibration is used in this paper. An optical software is used to design a star sensor optical system and then verify the distortion model. This paper uses a modified Kalman Filter to conduct the on-orbit calibration of thermal distortion.Moreover, this paper researches on the image plane displacement error of star sensor. An original six-degree-of-freedom displacement model is built, and the effect of image plane displacement on star sensor’s measurement error is analyzed. And a new iteration estimation algorithm with a changeable feedback parameter is introduced. This algorithm’s effectiveness is verified by simulating several estimation models. This paper uses the iteration estimation algorithm based on Extended Kalman Filter to calibrate the displacement.In addition, this paper researches on the effect of star sensor’s image plane displacement on star point extracting. The centroid algorithm and the Gauss curved fitting algorithm are compared. Two calibration methods of image plane displacement with the consideration of extracting process are introduced. The effect of star sensor’s image plane displacement on star point extracting is analyzed. This paper indicates that the displacement should be calibrated after the extracting process.Finally, this paper verifies simulately the big effect of star sensor’s image plane displacement on spacecraft’s attitude control system. A simulation model of satellite attitude control is built, and star sensor’s image plane displacement is added into the simulation model. The effect of star sensor’s image plane displacement on spacecraft’s attitude control accuracy is analyzed. And the displacement’s effect and the gyro error’s effect are compared.