491results about "Magnetic field offset compensation" patented technology

The invention discloses a Hall sensor combination system and method for magnetic imaging stability optimization. The system comprises a three-dimensional orthogonal Hall sensor array; the embedded encoder module is used for converting the analog magnetic field signals acquired by the sensor array into digital encoding signals with timestamps; the control module constructs an electromagnetic feature extraction model and is used for carrying out time-frequency domain conjoint analysis on the digital coding signals to obtain magnetic environment disturbance feature parameters; generating a compensation magnetic field parameter opposite to the magnetic environment disturbance characteristic parameter by adopting a closed-loop feedback mechanism; establishing a real-time data channel with a preset electromagnetic imaging module and a preset magnetic field generation module through a preset communication protocol; and constructing a magnetic environment state space model corresponding to the three-dimensional orthogonal Hall sensor array, and obtaining magnetic field distribution data to dynamically adjust and compensate magnetic field parameters so as to realize active magnetic interference cancellation in a three-dimensional space. Problems in the prior art can be effectively solved, and the precision and stability of magnetic imaging are improved.

The invention discloses an external magnetic field active-disturbance-rejection control method and system based on Kalman filtering, and the method comprises the steps: firstly, building an external coil control system to compensate a residual magnetic field in a magnetic shielding cabin measured by a three-axis fluxgate sensor, and enabling the residual magnetic field to be reduced to a normal working range of Quspin; then starting a Quspin sensor, performing data filtering and fusion on the fluxgate sensor and the Quspin sensor through a Kalman filter, and inputting a fusion value and a control quantity into an extended state observer to realize online estimation of a state and total disturbance; and performing feedback control of related linear state errors on the total disturbance estimator so as to compensate a residual magnetic field and magnetic field disturbance in the magnetic shielding cabin. The magnetic field interference resistance of the active magnetic compensation device can be enhanced, the control precision of an external coil control system on the magnetic field in the cabin is effectively improved, and the cost of the magnetic shielding cabin is reduced.

The invention belongs to the technical field of magnetic particle imaging, particularly relates to a magnetic particle imaging system and method based on a flexible receiving coil array, and aims to solve the problems that an existing rigid receiving coil is poor in biological surface adaptability and low in signal-to-noise ratio for micro geometric texture imaging. According to the structure, a receiving coil array adheres to the surface of an object to be measured, the receiving coil array and a compensation coil array are distributed on the two sides of a flexible substrate, the receiving coil array is used for receiving magnetic nanoparticle signals, and the partitioned small compensation coil array is used for conducting feed-through interference and electromagnetic interference compensation on a receiving coil; the reconstruction method comprises the following steps: sequentially carrying out Fourier transform on the collected receiving signals, extracting in-phase third harmonics and superposing to obtain processed signals, interpolating to construct a sinogram for Cartesian coordinate distribution, and reconstructing the three-dimensional particle concentration distribution of a measured object by a filtering back projection method. A flexible receiving coil array strategy is adopted, an adaptive reconstruction method is provided, and the imaging signal-to-noise ratio is improved.

A calibration method of the magnetic field model and a controller for electromagnetic positioning are provided. In the method, a magnetic field is established through a magnetic field transmitter; measurement data is obtained through a magnetic field sensor, where the measurement data includes the amplitude of induced voltage at multiple measurement positions in the magnetic field; and the magnetic field model is corrected according to the error between the measurement data and simulated data correction, where the magnetic field model is used to generate simulation data corresponding to multiple measurement locations. The steps of modifying the magnetic field model include: establishing one or more objective functions through the nonlinear least squares method based on the error between the measured data and the simulated data; and determining the modified magnetic field model based on one or more solutions of the objective function. Therefore, positioning accuracy can be improved.

The invention discloses an electromagnetic interference suppression method and system for ultra-low field magnetic resonance imaging, and belongs to the technical field of nuclear magnetic resonance, and the system comprises an electromagnetic interference signal collection module which is composed of a plurality of EMI coils and corresponding signal collectors and actively detects EMI signals from the environment; the electromagnetic interference suppression module is used for performing model training by using the data, performing electromagnetic interference suppression through a model, predicting and eliminating an EMI component based on the electromagnetic interference suppression model, and outputting k space data without EMI; and the image reconstruction module is used for receiving the EMI-free k-space data and carrying out averaging and image reconstruction on the data so as to generate a high-quality MRI image. According to the invention, EMI noise is effectively suppressed, image quality is improved, and mobile and portable development of MRI equipment is promoted.

The invention is applicable to the technical field of magnetic field measurement, and provides a current sensor magnetic field measurement method based on a tunneling magnetoresistance effect, which comprises the following steps of: analyzing a real-time output signal through a machine learning algorithm based on a mapping relation model of a parasitic capacitance parameter and a signal characteristic of a tunneling magnetoresistance sensor circuit; determining an actual value of a parasitic capacitance parameter; controlling a negative capacitance generation circuit and a numerical control resistance network to adjust an equivalent negative capacitance value and a resistance value according to the actual value of the parasitic capacitance parameter, and generating a matched compensation parameter set; feature extraction is carried out on the compensated signal, and an effective magnetic field component is obtained through multi-resolution time domain decomposition and phase consistency detection; calculating the magnetic field intensity and the change gradient based on the effective magnetic field component, and determining the effective working frequency range of the sensor according to the signal attenuation characteristic; and dynamically adjusting a compensation strategy according to a comparison result of the effective working frequency range and a preset target frequency band, and reducing measurement errors.

A method for making axial magnetic field measurements in a downhole tool includes evaluating axial magnetic field measurements to determine a magnetic interference offset and removing the magnetic interference offset to obtain compensated axial magnetic field measurements.

The invention discloses a method and a system for detecting shielding performance of a shipborne paleomagnetic laboratory, and relates to the technical field of paleomagnetic laboratory detection. According to the invention, a plurality of measurement points are arranged in the shipborne paleomagnetic laboratory, so that the magnetic induction intensity data in the shipborne paleomagnetic laboratory can be accurately and fully measured, and the accuracy of subsequent calculation of the internal average residual magnetism and the shielding coefficient of the shipborne paleomagnetic laboratory is improved; the detection accuracy of the shielding performance of the shipborne paleomagnetic laboratory is further improved; the ship navigation state of the ship is continuously adjusted, the operation environment of the shipborne paleomagnetic laboratory is fully considered, and the situation that the shielding performance of the shipborne paleomagnetic laboratory is detected inaccurately due to the navigation uncertainty of the ship and the complex magnetic environment of the ship navigating in the ocean is avoided in a multi-ship navigation state and multi-measurement-point mode. The accuracy of the internal average residual magnetism and the shielding coefficient is improved through the dynamic characteristics of the ship, and the detection accuracy of the shielding performance of the shipborne paleomagnetic laboratory is ensured.

Systems, circuits, and methods provide self-calibration for magnetoresistance-based magnetic field sensors. Examples can include use of a closed loop acting as a feedback or calibration loop that is configured to process a reference signal applied to one or more magnetoresistance elements in a MR-based magnetic field sensor that also detects one or more external magnetic fields. The closed loop can adjust a bias voltage applied to the one or more magnetoresistance elements based on the reference signal. The calibration loop can accordingly provide for automatic or self-calibration of sensitivity of one or more magnetoresistance elements of the sensors to compensate for external factors affecting sensitivity of the one or more magnetoresistance elements.

An MR element includes a first magnetic layer, a second magnetic layer, and a nonmagnetic layer disposed between the first magnetic layer and the second magnetic layer. The first magnetic layer has a magnetic shape anisotropy set in a first reference direction, and has a magnetization whose direction changes depending on an external magnetic field, the magnetization being oriented in a first magnetization direction in a state where the external magnetic field is not applied. The second magnetic layer has a magnetic shape anisotropy set in a second reference direction, and has a magnetization whose direction changes depending on the external magnetic field, the magnetization being oriented in a second magnetization direction in a state where the external magnetic field is not applied.

To provide a magnetic sensor device in which influence of stress applied is suppressed.SOLUTION: A magnetic sensor device 1 comprises magnetic sensors 10, 20, 30, and a support medium 4. The center of mass of an element arrangement area of the magnetic sensors 10, 20, 30 is displaced from center of mass C4 of a reference plane 4a of the support medium 4. Each of the magnetic sensors 10, 20, 30 includes four resistance parts composed of a plurality of MR elements. Magnetization of a free layer 54 in two resistance parts contains a component in a third magnetization direction. Magnetization of the free layer 54 in each of the remaining two resistance parts contains a component in a fourth magnetization direction opposite to the third magnetization direction.SELECTED DRAWING: Figure 8

A current sensor assembly can include: a coil structure having a first coil and a second coil connected in series, the coil structure configured to generate a differential magnetic field responsive to an electrical current passing through the first and second coils; a first magnetic field sensing element disposed proximate to the first coil and operable to generate a first signal responsive to the differential magnetic field passing through the first magnetic field sensing element in a first direction; a second magnetic field sensing element disposed proximate to the second coil and operable to generate a second signal responsive to the differential magnetic field passing through the second magnetic field sensing element in a second direction; and a circuit operable to subtract the first and second signals to generate a differential signal proportional to the electrical current.

A calibration system leverages a 3-axis Helmholtz coil device for generating a referential magnetic field for calibrating the magnetometer on-board a vehicle. The calibration system may include the magnetic field generator, a vehicle platform, and a computing device to determine the calibration parameters. The vehicle platform supports the vehicle with the magnetometer being calibrated. The magnetic field generator generates a referential magnetic field in three-dimensional space for calibration of the magnetometer. The computing device is configured to: receive magnetometer measurements from the magnetometer on-board the vehicle during generation of the referential magnetic field, and determine calibration parameters for calibrating the magnetometer based on the magnetometer measurements and the referential magnetic field generated by the magnetic field generator.

A method for extracting information about one or more magnetic sources includes obtaining a first plurality of signals corresponding to magnetic sensor data generated by one or more magnetometers in an unshielded environment at a first time; receiving second information of a direction and a magnitude of a first known magnetic field applied to the one or more magnetometer, the first plurality of signals is acquired while the first known magnetic field is applied and wherein the first known magnetic field encodes directional information of the one or more magnetic sources into the first plurality of signals; extracting the information comprising three-dimensional spatial information of the one or more magnetic sources, respective orientations and strengths of the one or more magnetic sources based on the first information, the second information, and the plurality of signals corresponding to the magnetic sensor data.

The present invention relates to a probe for locating a magnetic marker for use during surgery. The probe comprises at least two first coils (3a, 3b) and at least one second coil (5) arranged substantially coaxially on a longitudinal axis of the probe for measuring the proximity of a magnetic marker to the probe, and a baseline voltage sensing device (7) comprising a first elongated conductor defining a conductive path extending partially around the axis of the probe. The conductive path is constructed and arranged to induce a balanced voltage in the sensing coils that, in use, at least partially offsets the baseline voltage. Methods of manufacturing such a probe, methods of configuring such a probe for use in sensing magnetic markers, and detection devices for locating a magnetic marker during surgery are also disclosed.

A system for detecting a target object including: a first and a second detector which have magnetic sensors configured to detect a magnetic field and to generate a signal which indicates a magnetic field intensity; a processing unit configured to receive the signals which indicate an intensity of a magnetic field detected by the sensors; and a communication interface which is configured to transmit the signals generated by the magnetic sensors to the processing unit, the processing unit additionally being configured to determine a corrected value of the signals generated by the magnetic sensors of the first and second detectors and, when the corrected value is greater than a predetermined threshold value, to send instructions for generating an alarm.

The present disclosure provides a method for optimizing a broadband noise of an inductive magnetic field sensor as well as a magnetic field sensor, including: determining a functional relationship between an induced voltage of a coil and an effective permeability of a magnetic core of the inductive magnetic field sensor; determining an equivalent voltage noise expression of a temperature variation-induced permeability noise of the magnetic core according to the functional relationship; determining a key influencing factor of the magnetic core according to the equivalent voltage noise expression of the temperature variation-induced permeability noise of the magnetic core; modifying the magnetic core according to the key influencing factor of the magnetic core to optimize the temperature variation-induced permeability noise of the magnetic core; and constructing a dual-channel composite multi-stage modulation signal-noise separation circuit to optimize a low-frequency band noise and a high-frequency band noise of the inductive magnetic field sensor.

A magnetometer with responsive material is provided that includes a PT symmetric assembly. The PT symmetric assembly includes gain material and responsive material that are positioned to achieve PT symmetry. The responsive material is configured to shift a resonance frequency of point defects in response to a magnetic field. A microwave antenna is configured to generate a microwave field of varying frequencies that engage the responsive material. A controller is configured to adjust a tunable laser source that is input into the PT symmetric assembly based on an output of the PT symmetric assembly to cause a gain generated by the gain material to match a loss caused by the responsive material. The controller is further configured to determine a strength of the magnetic field by determining one of a deviation from the exceptional point and an amplitude of the gain needed to reach the exceptional point.

The invention discloses a magnetic measurement method of a fluxgate sensor, which belongs to the technical field of electromagnetic detection, and comprises the following steps of: placing the fluxgate sensor at a calibration environment temperature, and applying an excitation signal with linearly converted frequency to collect an induced voltage signal; secondly, segmenting the acquired induced voltage signal according to frequency duration to obtain a plurality of induced voltage sub-signals, and recording a temperature value corresponding to each sub-signal; then, calculating signal quality according to the frequency spectrum information of the sub-signals, and selecting a plurality of sub-signals with the optimal quality; then, calculating magnetic field components of the signals, and screening out stable magnetic field components; finally, correction is carried out according to the deviation between the temperature value of the stable magnetic field component and the calibration environment temperature, a corrected magnetic field component is obtained, the magnetic field intensity is calculated, and the magnetic measurement precision of the fluxgate sensor is effectively improved.

To enhance the sensitivity of magnetic field intensity.SOLUTION: A photoexcitation magnetic sensor 1 comprises: a cell 2 filled with alkali metal vapor; a pump laser 4 and a first optical system 6 for making pump light incident on sensitivity regions ARa-ARd in the cell 2 along a y-axis direction; a probe laser 5 and a second optical system 7 for making probe light incident on the sensitivity regions ARa-ARd along an x-axis direction; a bias magnetic field coil 11 for applying a bias magnetic field By along the y-axis direction to the cell 2, and determining the resonant frequency of an electron spin; bias magnetic field gradient correction coils 12 and 13 for correcting the gradient of the bias magnetic field By; a tilting coil 14 for tilting the rotation axis direction of the electron spin; optical sensor pairs 43a-43d for detecting the probe light passed through the sensitivity regions ARa-ARd; and a reading circuit 10 for measuring magnetic field intensity on the basis of the output of the optical sensor pairs 43a-43d.SELECTED DRAWING: Figure 1

A probe for locating a magnetic marker for use in surgery. The probe comprises at least two first coils (3a, 3b) and at least one second coil (5) which are arranged substantially coaxially on a longitudinal axis of the probe for measuring the proximity of a magnetic marker to the probe, and a baseline voltage taring device (7) comprising a first elongate conductor which defines a conducting path extending partially around the probe axis. The conducting path is configured and arranged such that in use the balancing magnetic field induces a balancing voltage in a sense coil that at least partially offsets the baseline voltage. Also disclosed is a method of manufacturing such a probe, a method of setting up such a probe for use in sensing a magnetic marker, and detection apparatus for locating a magnetic marker during surgery.

In described examples, an integrated circuit (IC) written on a substrate that includes a substrate surface includes a magnetic concentrator, a Hall sensor, a primary coil, and a secondary coil. The Hall sensor at least partially overlaps the magnetic concentrator. The primary coil at least partially overlaps the magnetic concentrator. The secondary coil at least partially overlaps the magnetic concentrator and the primary coil, and surrounds the Hall sensor.

The present disclosure relates to a method (100) of magnetically calibrating a magnetometer sensing system (30) with respect to an electronic device (50), the method (100) comprising: detecting (110) a disturbing magnetic source (520) in the electronic device (50) relative to a reference coordinate system (X, Y, Z) of the magnetometer sensing system (30); identifying (120) one or more magnetometers (Sk,l) of the magnetometer sensing system (30) which are magnetically affected by the detected disturbing magnetic source (520); selecting (130) one or more balancing magnetic sources (400) to reduce a magnetic effect of the detected disturbing magnetic source (520) on the one or more identified magnetometers (Sk,l); and placing (140) the one or more selected balancing magnetic sources (400) in a fixed relation to the magnetometer sensing system (30) and / or to the disturbing magnetic source (520).

Systems, circuits, and methods provide self-calibration for magnetoresistance-based magnetic field sensors. Examples can include use of a closed loop acting as a feedback or calibration loop that is configured to process a reference signal applied to one or more magnetoresistance elements in a MR-based magnetic field sensor that also detects one or more external magnetic fields. The closed loop can adjust a bias voltage applied to the one or more magnetoresistance elements based on the reference signal. The calibration loop can accordingly provide for automatic or self-calibration of sensitivity of one or more magnetoresistance elements of the sensors to compensate for external factors affecting sensitivity of the one or more magnetoresistance elements.

The invention relates to a magnetic measuring device. In a magnetic measurement device provided with a plurality of sensor units having a variable relative positional relationship, even if the relative positional relationship of the plurality of sensor units is changed, the relative positional relationship of the plurality of sensor units after the change is easily identified. A magnetic measurement device (100) is provided with: a sensor unit (1) having one or more magnetic sensors (10); a sensor unit (2) having one or more magnetic sensors (10) and one or more magnetic field generating coils (20); and a movable mechanism (4) that changes the relative positional relationship between the sensor unit (1) and the sensor unit (2).

Disclosed herein is a magnetic field measurement device that includes a first sensor unit having one or more magnetic sensors, a second sensor unit having one or more magnetic sensors and one or more magnetic field generating coils, and a moving mechanism configured to change a relative positional relationship between the first and second sensor units.

An optically pumped magnetometer includes a cell, a pump light incidence unit causing pump light to be incident on a sensitivity region inside the cell in a first direction, a probe light incidence unit causing probe light for detecting change in electron spins to be incident on the sensitivity region in a direction intersecting the first direction, a bias magnetic field coil applying a bias magnetic field in the first direction to the inside of the cell and determining a resonance frequency of the electron spins, a gradient correction coil correcting a gradient of the bias magnetic field, an electron spin tilting unit tilting a rotation axis direction of the electron spins, an optical sensor detecting the probe light having passed through the sensitivity region, and a magnetic field measuring unit measuring a magnetic field strength related to the sensitivity region based on an output of the optical sensor.

A system, comprising: a sensing element including a plurality of resistive elements; a switching matrix that is configured to change a total resistance of the sensing element by bringing online or offline one or more of the plurality of resistive elements, the total resistance of the sensing element, at any point in time, being based on respective resistances of only those of the plurality of resistive elements that are currently online; a matrix controller that is configured to detect when a value of a counter signal is updated and cause the switching matrix to change the total resistance of the sensing element by bringing offline or online one or more of the plurality of resistive elements based on the value of the counter signal; and a counter signal generator configured to detect whether an offset signal satisfies a predetermined condition and update the value of the counter signal.

Disclosed herein is a magnetic sensor that includes a sensor chip having a magnetosensitive element, a magnetic field collecting body for collecting a magnetic field to the magnetosensitive element, an excitation coil wound around the magnetic field collecting body, and a modulation circuit that supplies an excitation current having a predetermined frequency to the excitation coil so as to periodically magnetically saturate the magnetosensitive element without magnetically saturating the magnetic field collecting body.