IEEE Trans Neural Syst Rehabil Eng. 2017 Dec;25(12):2398-2406. doi: 10.1109/TNSRE.2017.2760356. Epub 2017 Oct 6.
The direction of the Earth's magnetic field is used as a reference vector to determine the heading in orientation estimation with wearable sensors. However, the magnetic field strength is weak and can be easily disturbed in the vicinity of ferromagnetic materials, which may result in inaccurate estimate of orientation. This paper presents a novel method for estimating and compensating for magnetic disturbances. The compensation algorithm is implemented within a kinematic-based extended Kalman filter and is based on an assessment of the magnetic disturbance and the change of orientation in each time step. The proposed algorithm was experimentally validated by measuring the orientation of a simple mechanical system with three degrees of freedom in an artificially disturbed magnetic field. The results of the experimental evaluation show that an Kalman filter algorithm that incorporates compensating for magnetic disturbances is capable of estimating the orientation with moderate error (the absolute median errors , ) when the Earth's magnetic field is disturbed by magnetic disturbance with a magnitude equal to twice the magnitude of the Earth's own magnetic field in different directions.
地球磁场的方向被用作参考向量，以确定佩戴传感器的定向估计中的航向。然而，磁场强度较弱，在铁磁材料附近很容易受到干扰，这可能导致定向估计不准确。本文提出了一种新的估计和补偿磁场干扰的方法。补偿算法在基于运动学的扩展卡尔曼滤波器内实现，并且基于在每个时间步长评估磁场干扰和方向变化的基础上实现。该算法通过在人为干扰磁场中测量具有三个自由度的简单机械系统的方向进行了实验验证。实验评估的结果表明，当地球磁场受到与地球自身磁场强度相等的磁场干扰时，包含补偿磁场干扰的卡尔曼滤波器算法能够以中等误差（绝对中位数误差 ）估计方向， 在不同方向上。
