航姿参考系统三轴磁强计的两步校正算法

Two-step Calibration Algorithm of Three-axis Magnetometer in Attitude an Heading Reference System

针对MEMS三轴磁强计在线误差校正的需要,提出了两步校正算法。通过极大极小值法初步校正磁强计,利用零速检测获取载体的无干扰加速度区间,在该区间内利用重力矢量和地磁矢量的点积不变性求解误差矩阵,进一步校正磁强计。理论分析和实验测试均表明,这种两步校正算法克服了椭球拟合法的缺陷,能求解磁强计误差模型中的全部参数,从而实现更好的误差校正效果。

A two-step calibration algorithm is proposed for the online error correction of 3-axis MEMS magnetometer.In the first step,the zero offset of the magnetometer is evaluated and compensated by the maximal minimum value method.Then,the non-interference acceleration time intervals of moving carrier is obtained by zero velocity detection.In these intervals,the error matrix is solved according to the dot product invariance of gravity vector and geomagnetic vector,hence the magnetometer error can be corrected further.Theoretical analysis and experimental tests show that this two-step calibration algorithm has better results for MEMS magnetometer error correction than the traditional ellipsoid fitting method since it can solve all the parameters of magnetometer error model.