Iterative calibration technique of microsatellite magnetic sensor error in orbit based on multi-parameter algorithm

Magnetometer is the main instrument to determine the attitude of micro satellite. Magnetometer accuracy is an important indicator which influences the micro satellite attitude performance. In order to improve magnet estimation accuracy, in-orbit calibration based on multi-parameter is utilized in two stages to estimate the error of Magnetometer`s bias and scale factor. The results can be used to compensate the attitude algorithm, which improves the navigation accuracy of the satellite. Firstly, Based on the scale factor on the ground test as the standard, the bias is calibrated. Secondly, the error model is reconstructed with the result of the first stage. The optimal method is utilized to recalibrate the bias and scale factor. In this paper, sun sensor and gyro are used to measure and correct the magnetometer error. Magnetometer error estimation method is derived, and satellite pitch angle and angular velocity are calculated through the pith filter using the output of sun sensor and gyro. Then, outputs of the filter are used to calculate magnetometer error. The estimated results are used to correct the magnetometer outputs through the filter. Simulation shows that the method is effective, and enhances the stability of the satellite. It is favorable for imaging tasks, and improves the micro satellite navigation system performance.

I. Introduction

Magnetometer is the main instrument to determine the attitudes in micro satellite. Magnetometer accuracy is an important indicator which influences the micro satellite attitude performance [1]–[7]. Attitude measurement and control system of a low power micro satellite is composed of magnetometer, sun sensor, gyroscope, momentum wheel, and magnetic torque. The control system of micro satellite realizes inertial orientation by using constant speed momentum wheel, so an important work of the control system is to control the pitch attitude. Magnetometer is used to estimate pitch attitude and pitch attitude rate. Sun sensor gets sun information in the light period, which is integrated with the solar calendar to gain pitch attitude of satellite. What is more, when sun sensor is combined with magnetometer, the satellite pitch attitude can be calculated with filters. Because of gyroscope's high precision, but high power consumption, it is only configured in pitch direction and periodically monitors satellite pitch rate. The satellite remanence interference is the main error sources of the magnetometer. Remanent magnetization is generally controlled by prelaunch remanence measurement and compensation. However, the effect is limited. Remanent magnetization is still about 900 nT after compensation. It will produce large error in attitude measurement. Traditional in-orbit error calibration algorithms only calibrated zero-biased error. In fact, scale factor error of magnetometer can't be ignored too.