Calibration for a Multichannel Magnetic Sensor Array of a Magnetospinography System

Adachi, Yoshiaki; Higuchi, Masanori; Oyama, Daisuke; Haruta, Yasuhiro; Kawabata, Shigenori; Uehara, Gen

doi:10.1109/tmag.2014.2326869

Cited by 22 publications

(18 citation statements)

References 8 publications

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“…To account for different measurement uncertainties we use three sets of equations: integrated discrete-time strapdown IMU navigation equations, as can be found in [27,Ch. 7], simplified motion capture measurement equations, and magnetic measurement equations corresponding to (9). The augmented problem is then reformulated as a non-linear least-squares identification problem in the same manner as in (11) and (12).…”

Section: Real-world Experimentsmentioning

confidence: 99%

“…These techniques require a homogeneous and static magnetic field to achieve a good calibration precision, which implies manual outdoor data collection or expensive setups. Other techniques exploit gyrometers , coil‐generated homogeneous magnetic fields , or coil‐generated inhomogeneous magnetic fields . Strictly speaking, because calibration processes involving homogeneous magnetic fields do not give access to sensor effective positions, magnetic field gradiometers that rely on the knowledge of such positions cannot be calibrated this way.…”

Section: Introductionmentioning

confidence: 99%

“…Strictly speaking, because calibration processes involving homogeneous magnetic fields do not give access to sensor effective positions, magnetic field gradiometers that rely on the knowledge of such positions cannot be calibrated this way. Among the techniques involving inhomogeneous magnetic fields, the one discussed in requires accurate manipulations, and describe a simple process for calibrating Superconducting Quantum Interference Device (SQUID) magnetometers, but require that sensors be sensitive enough to measure the generated magnetic field. The problem of precisely calibrating an array of single‐axis magnetometers is still not satisfactorily solved in order to be applicable in so‐called magneto‐inertial dead‐reckoning applications, which in general do not use SQUID magnetometers.…”

Section: Introductionmentioning

confidence: 99%

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Calibration of a magnetometer array using motion capture equipment

Chesneau

Robin

Meier

et al. 2019

Asian Journal of Control

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This paper studies the problem of calibrating an array of single-axis magnetometers in an unknown static inhomogeneous magnetic field using motion capture equipment. A proof of identifiability is given, practical identifiability of calibration parameters is established in simulation, and real world experiments are conducted to demonstrate the feasibility of this approach. Unlike many state of the art techniques, the proposed solution does not require a homogeneous field, as in fact, we demonstrate that an inhomogeneous field enlarges the set of identifiable parameters. Under the above-mentioned assumptions, this approach may be used to extend self-calibration techniques of visual-inertial setups to magnetic sensor arrays in indoor environments.

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Section: Real-world Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calibration of a magnetometer array using motion capture equipment

Chesneau

Robin

Meier

et al. 2019

Asian Journal of Control

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“…Calibration of a SQUID chip Figure 6a shows the experimental setup, including a Circular Current Array System (Higuchi et al 1989;Yoshida et al 1994;Adachi et al 2014), for the calibration of a SQUID sensor. The measurements were made in a magnetically shielded room of two-layered PC permalloy with a shielding factor of 1/100 at 1 Hz.…”

Section: Calibration and Evaluationmentioning

confidence: 99%

“…The measurements were made in a magnetically shielded room of two-layered PC permalloy with a shielding factor of 1/100 at 1 Hz. The Circular Current Array System is also used to determine the sensitivity and positioning of the SQUID sensor array used for magnetoencephalography or magnetospinography (Adachi et al 2014). The Circular Current Array System used in this study has the same setup as that shown in Fig.…”

Section: Calibration and Evaluationmentioning

confidence: 99%

Scanning SQUID microscope system for geological samples: system integration and initial evaluation

Oda

Kawai

Miyamoto

et al. 2016

Earth Planets Space

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We have developed a high-resolution scanning superconducting quantum interference device (SQUID) microscope for imaging the magnetic field of geological samples at room temperature. In this paper, we provide details about the scanning SQUID microscope system, including the magnetically shielded box (MSB), the XYZ stage, data acquisition by the system, and initial evaluation of the system. The background noise in a two-layered PC permalloy MSB is approximately 40-50 pT. The long-term drift of the system is approximately ≥1 nT, which can be reduced by drift correction for each measurement line. The stroke of the XYZ stage is 100 mm × 100 mm with an accuracy of ~10 µm, which was confirmed by laser interferometry. A SQUID chip has a pick-up area of 200 μm × 200 μm with an inner hole of 30 μm × 30 μm. The sensitivity is 722.6 nT/V. The flux-locked loop has four gains, i.e., ×1, ×10, ×100, and ×500. An analog-to-digital converter allows analog voltage input in the range of about ±7.5 V in 0.6-mV steps. The maximum dynamic range is approximately ±5400 nT, and the minimum digitizable magnetic field is ~0.9 pT. The sensor-to-sample distance is measured with a precision line current, which gives the minimum of ~200 µm. Considering the size of pick-up coil, sensor-to-sample distance, and the accuracy of XYZ stage, spacial resolution of the system is ~200 µm. We developed the software used to measure the sensor-to-sample distance with line scan data, and the software to acquire data and control the XYZ stage for scanning. We also demonstrate the registration of the magnetic image relative to the optical image by using a pair of point sources placed on the corners of a sample holder outside of a thin section placed in the middle of the sample holder. Considering the minimum noise estimate of the current system, the theoretical detection limit of a single magnetic dipole is ~1 × 10 −14 Am 2 . The new instrument is a powerful tool that could be used in various applications in paleomagnetism such as ultrafine-scale magnetostratigraphy and single-crystal paleomagnetism.

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