IVMD降噪下的磁梯度张量系统集成校准方法

磁梯度张量系统（MGTS）经过校准能够减小传感器系统误差、阵列非对准误差和载体磁干扰误差，但磁测信号常受到环境电磁场、地磁脉冲信号等噪声的干扰，使得系统校准精度受限。为此，提出了在独立变分模态分解（IVMD）降噪下的MGTS集成校准方法。首先，进行旋转采样获得足量磁场矢量信号，并合成为总场强度和方向信号以避免降噪失真；然后，利用谱循环相关系数对信号进行端点延拓以抑制端点效应，对合成信号进行变分模态分解（VMD），并对主分量进行核独立成分分析（KICA），进一步消除噪声和模态混叠；最后，利用集成补偿和旋转对准（ICRA）方法的一步校准系统，消除系统误差、非对准误差和硬软磁干扰的影响。实测表明，相较于ICRA直接校准，该方法在室内电场环境中将张量分量均方根误差（RMSE）由近100 nT/m约束在5.6 nT/m内；在磁性目标定位实验中，定位距离均方根误差由0.157 m减小至0.066 m。

Integrated Calibration Method of Magnetic Gradient Tensor System with IVMD Noise Reduction

The magnetic gradient tensor system (MGTS) can be calibrated to reduce the systemic error of sensors, misalignment error of arrays, and magnetic interference error of carriers. However, the measured signal is also interfered by the ambient electromagnetic field, the geomagnetic pulse and other noises, which limits the accuracy of the system calibration. Hence, an integrated calibration method of MGTS with independent variational modal decomposition (IVMD) is proposed. Firstly, the sufficient magnetic field vector signals can be obtained by rotation samplings and synthesized into the total field strength and direction signals to avoid noise reduction and distortion. Then, the signal end-point extension is conducted with the spectral cyclic correlation coefficient, the synthesized signals are processed with variational mode decomposition (VMD), and the major intrinsic mode functions (IMFs) are analyzed with the kernel independent component analysis (KICA) to further eliminate noise and modal aliasing. Finally, the system is calibrated with the method of integrated compensation and rotation alignment (ICRA) to eliminate the influences of the systemic error, the misalignment error and the hard and soft magnetic interferences. The experiments show that this method constrains the root mean square error (RMSE) of the tensor components from nearly 100 nT/m to within 5.6 nT/m in the indoor electric field environment, compared with direct calibration with ICRA; the RMSE of the target positioning distance is reduced from 0.157 m to 0.066 m in the magnet target positioning experiment.