Department of Electrical, Electronic and Information Engineering, University of Bologna, Viale del Risorgimento, 2, 40136 Bologna, Italy.
Sensors (Basel). 2019 Jan 11;19(2):280. doi: 10.3390/s19020280.
While the undisturbed Earth's magnetic field represents a fundamental information source for orientation purposes, magnetic distortions have been mostly considered as a source of error. However, when distortions are temporally stable and spatially distinctive, they could provide a unique magnetic landscape that can be used in different applications, from indoor localization to sensor fusion algorithms for attitude estimation. The main purpose of this work, therefore, is to present a method to characterize the 3D magnetic vector in every point of the measurement volume. The possibility of describing the 3D magnetic field map through Thin Plate Splines (TPS) interpolation is investigated and demonstrated. An algorithm for the simultaneous estimation of the parameters related to magnetometer calibration and those describing the magnetic map, is proposed and tested on both simulated and real data. Results demonstrate that an accurate description of the local magnetic field using TPS interpolation is possible. The proposed procedure leads to errors in the estimation of the local magnetic direction with a standard deviation lower than 1 degree. Magnetometer calibration and magnetic field mapping could be integrated into different algorithms, for example to improve attitude estimation in highly distorted environments or as an aid to indoor localization.
虽然未受干扰的地球磁场是定向的基本信息源，但磁场畸变大多被视为误差源。然而，当畸变具有时间稳定性和空间独特性时，它们可以提供独特的磁场景观，可用于不同的应用，从室内定位到传感器融合算法的姿态估计。因此，这项工作的主要目的是提出一种在测量体积的每个点上描述三维磁场矢量的方法。研究并演示了通过薄板样条（TPS）插值来描述三维磁场图的可能性。提出了一种同时估计磁力计校准参数和描述磁场图参数的算法，并在模拟和真实数据上进行了测试。结果表明，使用 TPS 插值可以对局部磁场进行精确描述。所提出的程序导致局部磁场方向估计的误差，其标准偏差低于 1 度。磁力计校准和磁场绘图可以集成到不同的算法中，例如，在高度失真的环境中提高姿态估计，或作为室内定位的辅助手段。
