The integrated INS/magnetometer measurement is widely used in low-cost navigation systems. The integration has proven more effective in suppressing the divergence of heading than relying solely on a magnetometer because this is susceptible to local magnetic field interference, reducing heading accuracy. Magnetometers sense the local magnetic field that may be interfered by the nearby ferromagnetic material or strong electric currents. Hence, the magnetometer must be calibrated in the vehicle before use. When a magnetometer is installed near power components (engines, etc.), soft iron interference can be ignored. In the vehicle’s external environment, the time-varying hard iron interference can reach 100 times the strength of the geomagnetic field, meaning that a magnetometer cannot function efficiently because its accuracy is so reduced. Hence, the constant hard magnetic interference inside the vehicle is mainly concerned in this paper. An INS/Magnetometer heading estimation algorithm based on a two-stage Kalman filter is proposed to solve the problem by combining inertial sensor and magnetometer with attitude information. In the first stage filter, the constant hard iron interference is estimated by setting upward standing the three IMU axes. In the second stage filter, the INS/Magnetometer heading estimation is implemented. Finally, the results show that the algorithm improves the accuracy of vehicle heading calculations.

集成 INS/磁力计测量广泛用于低成本导航系统。事实证明，这种集成在抑制航向发散方面比仅依靠磁力计更有效，因为磁力计容易受到局部磁场干扰，从而降低航向精度。磁力计检测可能受到附近铁磁材料或强电流干扰的局部磁场。因此，磁力计在使用前必须在车辆中进行校准。当磁力计安装在动力部件（发动机等）附近时，软铁干扰可以忽略不计。在车辆外部环境中，随时间变化的硬铁干扰可以达到地磁场强度的100倍，这意味着磁力计由于精度降低而无法有效发挥作用。因此，本文主要关注车内恒定的硬磁干扰。针对惯性传感器和磁力计与姿态信息相结合的问题，提出了一种基于两级卡尔曼滤波器的惯性导航系统/磁力计航向估计算法。在第一级滤波器中，通过将三个 IMU 轴向上设置来估计恒定的硬铁干扰。在第二级滤波器中，实现了惯性导航系统/磁力计航向估计。最后，结果表明该算法提高了车辆航向计算的精度。针对惯性传感器和磁力计与姿态信息相结合的问题，提出了一种基于两级卡尔曼滤波器的惯性导航系统/磁力计航向估计算法。在第一级滤波器中，通过将三个 IMU 轴向上设置来估计恒定的硬铁干扰。在第二级滤波器中，实现了惯性导航系统/磁力计航向估计。最后，结果表明该算法提高了车辆航向计算的精度。针对惯性传感器和磁力计与姿态信息相结合的问题，提出了一种基于两级卡尔曼滤波器的惯性导航系统/磁力计航向估计算法。在第一级滤波器中，通过将三个 IMU 轴向上设置来估计恒定的硬铁干扰。在第二级滤波器中，实现了惯性导航系统/磁力计航向估计。最后，结果表明该算法提高了车辆航向计算的精度。