三轴磁强计实时自校正算法

Real-Time Self Calibration Algorithm for Three-Axis Magnetometer

提出一种三轴磁强计的实时自校正算法.通过分析测量误差因素,建立了三轴磁强计输出的参数模型.在此基础上,根据定点地磁场矢量模不变原则建立校正相关参数的非线性状态空间模型,导出了基于扩展卡尔曼滤波器(Extended Kalman Filter,EKF)求解的校正参数估计算法,并相应给出了易于实现的U-D分解滤波形式.相比离线校正,新算法能够对校正参数进行实时估计,且更易于片上实现.通过数值仿真验证了算法推导的正确性.采用三轴磁强计RM3000进行实测校正试验,验证了算法的有效性,并将结果与离线的TWO-STEP算法进行了对比,得出了相应结论.

A real-time self calibration approach for tri-axis magnetometers is proposed. The parameterized model of magnetometer readings is established by analyzing the nature of sensor errors,which lays a basis for the derivation of a nonlinear state-space model of calibration parameter using the invariability of local geomagnetic field. The real-time estimation of calibration parameter is derived based on extended Kalman filter（ EKF） solution,the U-D decomposition filter is given for ease of implementation. Compared with the batch approaches,the proposed method not only can achieve real-time estimation of calibration parameters,but also is convenient for embedded implementation. Simulation results demonstrate the correctness of the derivation of the proposed approach. The effectiveness is validated by experimental test using RM3000 tri-aixs magnetometer. The results of simulations and experiments are analyzed and concluded in comparisons with TWO-STEP method.