Calibration of SQUID Magnetometers in Multichannel MCG System Based on Bi-Planar Coil

Yang, Kang; Wu, Dan; Gao, Wengen; Ni, Tianming; Zhang, Qiannian; Zhang, Hongwei; Huang, Dengchao

doi:10.1109/tim.2022.3150588

Cited by 16 publications

(10 citation statements)

References 27 publications

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“…We compare the proposed AnFIPNet with the following methods: (MUSIC) algorithm; [ 33 ] PDDA; [ 18 ] MHSA‐EC; [ 22 ] Hi‐Loc; [ 23 ] attention‐based IPS model by Tang et al; [ 24 ] Gaussian–Bernoulli restricted Boltzmann machine plus liquid‐state machine (GBRBM + LSM); [ 34 ] time series attentional prototype network (TapNet); [ 20 ] CNN‐based joint APs model by Koutris et al; [ 9 ] and 2D image CNN by Hajiakhondi et al [ 11 ] For the MUSIC and PDDA algorithm, due to various interference and complex indoor environments, we remove 10% maximum and minimum phase difference outliers of each anchor to mitigate the phase difference ﬂuctuations. After deriving the angle estimations from anchors, we use the least squares to estimate the final 2D positions.…”

Section: Methodsmentioning

confidence: 99%

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Deep Learning‐Based Bluetooth Low‐Energy 5.1 Multianchor Indoor Positioning with Attentional Data Filtering

Lyu,

Chan,

Hung

et al. 2023

Advanced Intelligent Systems

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Indoor positioning system (IPS) technologies have widespread applications in logistics, intelligent manufacturing, healthcare monitoring, etc. The recently released Bluetooth low‐energy (BLE) 5.1 specification enables in‐phase and quadrature‐phase (I/Q) data measurements. It allows angle of arrival estimation and becomes a natural choice for IPS implementation. Conventional BLE 5.1 IPSs use multiple anchors to provide massive redundancy to improve system robustness. It however demands effective approaches to leverage redundancy. Besides, interference due to various environmental factors can introduce severe errors to I/Q data and affect positioning accuracy. Facing these challenges, herein, a novel deep learning‐based multianchor BLE 5.1 IPS is proposed. The system aggregates measurements from multiple anchors and makes them available at regular time steps. Then, a novel attentional filtering network tailored to infer high‐quality I/Q sample data is developed and a spatial regularization loss incorporating spatial location relationships to strengthen the feature embedding discrimination is proposed. Two multianchor BLE 5.1 I/Q sample datasets are developed and released for public download. Numerical experiments are carried out to compare the proposed method with previous BLE 5.1 IPS methods and methods utilizing other radio frequency data. Results indicate that the proposed method consistently achieves submeter accuracy and significantly outperforms the state‐of‐the‐art approaches.

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Section: Methodsmentioning

confidence: 99%

“…To implement the models MHSA‐EC, [ 22 ] Hi‐Loc, [ 23 ] GBRBM + LSM, [ 34 ] TapNet, [ 20 ] Hajiakhondi, et al, [ 11 ] and Koutris, et al [ 9 ] on our datasets, we transform the data into the default format defined in their original papers. The data construction process is illustrated as follows.…”

Section: Methodsmentioning

confidence: 99%

Deep Learning‐Based Bluetooth Low‐Energy 5.1 Multianchor Indoor Positioning with Attentional Data Filtering

Lyu,

Chan,

Hung

et al. 2023

Advanced Intelligent Systems

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“…Large-scale magnetic shielding devices, used high permeable magnetic materials and high conductivity materials, such as permalloy and aluminum, to prevent the external magnetic field from entering its interior, based on the flux shunt effect [ 1 , 2 , 3 ] and eddy current effect [ 4 , 5 ], are used to provide extremely weak magnetic field environment. In the weak magnetic environment, many scholars have carried out frontier work, such as the measurement of biological signals such as magnetocardiography and magnetoencephalography [ 6 , 7 , 8 ], the measurement of geophysical research samples [ 9 ], the measurement of electric dipole moments [ 10 ], research on high-precision magnetic measuring instruments, such as serf atomic gyroscopes and magnetometers [ 11 , 12 ] and so on. Since the internal magnetic field of the magnetic shielding device is very small, the remanence of internal supporting structures (such as platforms for placing instruments) and scientific instruments equipment (such as cardio brain magnetic equipment) may have a greater impact on the internal magnetic field, so the remanence of the magnetic shielding device should be analyzed when selecting the supporting material of the magnetic shielding device.…”

Section: Introductionmentioning

confidence: 99%

Testing and Analysis Method of Low Remanence Materials for Magnetic Shielding Device

et al. 2023

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Magnetic shielding devices with a grid structure of multiple layers of highly magnetically permeable materials (such as permalloy) can achieve remanent magnetic fields at the nanotesla (nT) level or even lower. The remanence of the material inside the magnetic shield, such as the building materials used in the support structure, can cause serious damage to the internal remanence of the magnetic shield. Therefore, it is of great significance to detect the remanence of the materials used inside the magnetic shielding device. The existing test methods do not limit the test environment, the test process is vulnerable to additional magnetic field interference and did not consider the real results of the material in the weak magnetic environment. In this paper, a novel method of measuring the remanence of materials in a magnetic shielding cylinder is proposed, which prevents the interference of the earth’s magnetic field and reduces the measurement error. This method is used to test concrete components, composite materials and metal materials commonly applicated in magnetic shielding devices and determine the materials that can be used for magnetic shielding devices with 1 nT, 10 nT and 100 nT as residual magnetic field targets.

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“…Another approach for SQUID sensor calibration after cooling is to apply large square Helmholtz-like coils placed outside the cryostat to generate reference magnetic fields [8][9][10]. Yang et al proposed a special bi-planar coil designed using the target field method to allow application of a uniform reference magnetic field instead of Helmholtz coils [11]. A method of calibration using a single coil to generate reference magnetic fields from multiple locations while changing the relative distance to the cryostat was also proposed [12].…”

Section: Introductionmentioning

confidence: 99%

A Spherical Coil Array for the Calibration of Whole-Head Magnetoencephalograph Systems

Adachi

Oyama

Higuchi

et al. 2023

IEEE Trans. Instrum. Meas.

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We proposed a spherical coil array for determining the positions, orientations, and sensitivities of the magnetometers for whole-head magnetoencephalograph (MEG) systems. The coil array comprises 16 concentric and symmetrically oriented circular coils with a diameter of 150 mm, which is larger than those of conventional calibration coil arrays, such as 5 mm or 60 mm. The accuracy of the calibration was expected to improve because the relative mechanical errors in machining and assembly could be reduced when the coil diameter was increased. Moreover, we also proposed a method to estimate the uncertainties in calibration, and it was demonstrated that the sensor parameters of each sensor were successfully obtained with uncertainties using a spherical calibration coil array. Additionally, the accuracy of the calibration was evaluated using a dry-type MEG phantom, and as expected, it was found that the accuracy was improved from that of a conventional calibration coil array composed of an assembly of multiple 3-axis bobbins.

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Calibration of SQUID Magnetometers in Multichannel MCG System Based on Bi-Planar Coil

Cited by 16 publications

References 27 publications

Deep Learning‐Based Bluetooth Low‐Energy 5.1 Multianchor Indoor Positioning with Attentional Data Filtering

Deep Learning‐Based Bluetooth Low‐Energy 5.1 Multianchor Indoor Positioning with Attentional Data Filtering

Testing and Analysis Method of Low Remanence Materials for Magnetic Shielding Device

A Spherical Coil Array for the Calibration of Whole-Head Magnetoencephalograph Systems

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