A new compensation method for magnetic field distortions based on a 3-D Helmholtz coil

High-accuracy geomagnetic vector measurements inevitably suffer from the magnetic interference derived from ferromagnetic materials and electric equipment. Traditionally, to eliminate the influence of magnetic interference, a compensation process can be implemented to estimate the interference parameters that contain hard-iron and soft-iron parameters. The traditional compensation method did not consider the situation where the interference parameters would vary over time due to the change in magnetic properties. To overcome this problem, we proposed an evolutionary compensation method based on the Woodbury equation. Using this approach, the interference parameters can be iteratively updated during the measurement process by combining the previous information and the latest measurement data. Both simulation and experimentation were undertaken to evaluate the effectiveness of our proposed approach. The results demonstrate that the proposed method is successful in minimizing the impact of magnetic interference variations. The experiment shows that the RMS errors of geomagnetic filed total intensity and three components can be decreased from 4042.57 nT, 1425.84 nT, 5342.40 nT, and 2921.34 nT to 170.57 nT, 58.39 nT, 207.99 nT and 137.75 nT respectively by traditional method, while with evolutionary method the errors can be reduced to 47.37 nT, 16.19 nT, 57.61 nT and 38.38 nT respectively.

Section: Evolutionary Compensation Using Woodbury Equationmentioning

confidence: 99%

“…They arrived at the conclusion that the symmetrical strategy can provide the best data. Li et al [13] built a system to compensate the magnetic interference field by using a 3D Helmholtz coil. However, the involved experimental quantities should be measured exactly and the experimental cost is expensive.…”

Section: Introductionmentioning

confidence: 99%

A geomagnetic vector evolutionary compensation method using Woodbury equation

Zhang,

Liu,

et al. 2023

“…where η and B min are the field inhomogeneity and intensity taking into account the cross-sectional effect, while η 0 and B min0 are the ideal values formulated by ( 15)- (23). By integrating equations ( 7) and ( 8) along both the axial and radial directions, the magnetic field generated by the circular three-coil and four-coil with cross-section can be numerically expressed as (26) and (27), respectively. In the analysis, the cross-sectional parameters are normalized as w/s, h 1 /s and h 2 /s.…”

Section: Analysis Of the Cross-sectional Effectmentioning

confidence: 99%

“…With the increasing applications of HMF, traditional coil systems and their optimized forms have drawn extensive attention [21][22][23]. These classical coaxial coil systems and their derived forms have been widely used in measurement improvement [24][25][26][27], wireless power transfer [28,29], robotic motion control [30] and magnetic resonance imaging [31,32]. So far, the main constraints arising in the HMF generation community can be summarized as the following two aspects.…”

Section: Introductionmentioning

confidence: 99%

Optimized and standardized circular-coil systems for homogeneous magnetic field generation

Lu¹,

Yang²,

Wang³

et al. 2022

Nowadays, there is a rising demand for the homogeneous magnetic field (HMF) as exposure resource for electrical immunity tests, biomedical experiments, etc. The design of the conventional HMF generators such as Helmholtz and Barker coils only focuses on the field homogeneity at the coil center, which leads to limitations in the available workspace of HMF. In this paper, based on a comprehensive definition of HMF, the optimized circular three-coil and four-coil systems were analyzed through an optimization method. By standardizing the coil parameters to the HMF parameters, it is easy to scale the coil systems for the desired HMF. In addition, two sets of concise formulae were presented as practical design tools. In comparison with the classic Barker coils, the proposed optimized coil systems enable a highlighted reduction in both total electrical power and conductor mass by 14.9% to 33.6%. Numerical simulations and experimental tests were presented to show the effectiveness of the theoretical results and the improvement in coil performances.

“…However, only the modulus of the distortion field was calculated to compensate for the total field, which led to the loss of vector information of real-time magnetic intensity. Li et al [19] proposed a distortion field compensation method based on the Rauch-Tung-Striebel fixed-interval smoothing method and singular value decomposition, which contributed to the improvement of magnetic measurement accuracy in the dynamic environment. These methods helped to construct more precise distortion models in a dynamic environment.…”

Section: Introductionmentioning

confidence: 99%

A novel magnetic calibration method based on an extended shaping filter

Ma¹,

Zhang²,

Li³

2023

Self Cite

During maneuvering of high-speed aircraft, the eddy-current magnetic field has a significant impact on the real-time geomagnetic field measurement accuracy. However, it is difficult to estimate the eddy-current component directly when it is considered in the magnetic distortion model. In this paper, we proposed a geomagnetic field estimation method based on a shaping filter. Soft-iron, hard-iron and eddy-current field distortions were considered in the compensation system. In the estimation process, a higher-order shaping filter is designed to coincide the higher-order statistics of the alternative system with the input of the original system. Simulation results showed that our proposed method could accurately estimate the eddy-current field. Compared with methods that do not consider the eddy-current field, the root-mean-square error of the geomagnetic field could be reduced by more than 50%, thus significantly improving the accuracy of geomagnetic field measurement.