一种考虑g敏感性的MIMU系统级标定方法研究

A System-level Calibration Method Considering the g-sensitivity for MIMU

针对微机械惯性测量单元(micro-electro-mechanical-system inertial measurement unit,MIMU)中存在陀螺漂移的g敏感性以及因漂移误差大而无法进行自主方位对准问题,建立了MIMU系统级标定Kalman滤波状态空间模型,考虑g敏感性误差状态的影响,在量测方程中加入方位失准角变化率以增强g敏感性的状态估计可观性;直接采用外输入粗略初始方位角进行导航解算,降低地球自转角速度的影响,提高陀螺漂移估计精度。设计了一套完整的系统级标定转位编排方案,陀螺标定和加速度计标定相互依赖,共同协作完成MIMU系统级标定,能够有效分离出所有30个标定参数,利用某型号弹载MIMU进行了实物标定试验验证,分别用标定前后数据进行导航解算,对比导航结算结果发现标定后的3个方向的导航速度都降低了,加速度计的刻度因数和零偏标定精度更高。特别在MIMU存在多轴大角度转动情况下,近10 min内达到优于30 m/s的导航速度精度,验证了系统级标定具有较高的精度。

A MIMU system level calibration Kalman filter state space model is established to address the g-sensitivity of gyroscope drift and the inability to perform autonomous azimuth alignment due to large drift errors in micro electromechanical system inertial measurement unit(MIMU).Considering the influence of g-sensitivity error states,a rate of change of azimuth misalignment angle is added into its measurement equation to enhance the observability of g-sensitivity state estimation.It directly takes a rough initial azimuth angle as external input to perform navigation calculation,so as to reduce the influence of earth′s rotational angular velocity and improve the accuracy of gyroscope drift estimation.Meanwhile,a complete system level calibration and transposition arrangement scheme is designed,in which gyroscope calibration and accelerometer calibration are interdependent and work together to complete MIMU system level calibration.It can effectively separate all 30 calibration parameters.To verify the results,a physical calibration experiment is conducted on a certain model of missile borne MIMU,its navigation calculations are performed using pre-and post calibration data.Comparing the navigation solution results,it shows that the navigation speed in all three directions decrease after calibration,and the calibration factor and zero bias calibration accuracy of the accelerometer are higher.Especially under a condition of the MIMU is rotated with multi axis and large angle,the navigation speed accuracy is better than 30 m/s within about 10 min,this verify that the accuracy of system level calibration is high.