The invention relates to a method for determining a coupling between magnetometers of an array of N magnetometers, for example with optical pumping, where each magnetometer comprises a field cancellation system capable of being activated to operate the magnetometer in zero field. This method comprises a first phase (P1) during which the N magnetometers are separated into N−1 magnetometers whose field cancellation system is deactivated and a measuring magnetometer whose field cancellation system is activated. This first phase comprises: the generation (GENj), by the magnetometers, of a plurality of reference magnetic fields of known amplitudes and distinct directions, the measurement (MESi), by the measuring magnetometer, of the ambient magnetic field on a plurality of measurement axes determination (CALCij) of coupling coefficients between the measuring magnetometer and each of the N magnetometers from said measurement and said known amplitudes.

This application discloses a vector sensor zero-point calibration method, device, and, apparatus, an electronic device, and a non-volatile computer-readable storage medium. The calibration method includes: acquiring reference data during two measurements of a reference vector performed by a vector sensor; acquiring a zero-point offset M.sub.0 of the vector sensor according to the reference data; acquiring original data R.sub.k of any vector measured by the vector sensor; and acquiring valid data V.sub.k according to the zero-point offset M.sub.0 and the original data R.sub.k. With the calibration method in this application, the valid data V.sub.k is obtained after a zero-point error of the original data R.sub.k is eliminated, which is more closely approximated to an actual value of a to-be-measured vector.

A digital compass with two or more multi-axis magnetometers and a processing element to determine a heading and detect any offset error in the heading is described. One electronic device includes first and second magnetometers. The second magnetometer can be disposed at least a specified distance or co-located and offset at least a specified angle from the first magnetometer. A processing device determines a magnetic field at the electronic device using a first output from the first magnetometer, detects an offset error in the magnetic field using a second output from the second magnetometer, and reports the offset error in the magnetic field.

There is provided a method and system for identifying the location of an obstruction in a pipeline comprising: sensing the magnetic field generated by a pipeline at an initial pressure from a first location along the length of the pipeline to obtain a baseline reading; altering the pressure from a first end until a maximum pressure or minimum pressure is attained; sensing the magnetic field at the maximum or minimum pressure from the first location to obtain a stress reading; and identifying the location of the obstruction as a) being between a second end and the first location when there is a deviation between the stress reading and the baseline reading at the first location or as b) being between the first end and the first location when there is an absence of a deviation between the stress reading and the baseline reading at the first location.

A three-axis magnetic sensor apparatus is described that is processed together into a single chip, with high performance, low cost, as well as small size. The three-axis magnetic sensor apparatus include a substrate, a two-axis magnetic sensing structure and a single-axis sensing structure. The two-axis sensing magnetic structure consisting of two shielded Wheatstone bridge configurations in conjunction with an annular or semi annular magnetic flux-guiding structure, and the single-axis sensing structure consisting of a push-pull Wheatstone bridge in conjunction with a flux guide that is capable of generating a fringe field whose horizontal component is proportional to the vertical component of an external magnetic field. The two-axis magnetic sensing structure and the single-axis structure are processed together into a single chip, and can be used to measure respectively X, Y and Z components of external magnetic fields.

A magnetic sensor circuit includes a plurality of magnetic sensors having bias input and bias output terminals and first and second measurement terminals. The circuit includes a diagnostic sensor having bias input and bias output terminals and first and second measurement terminals. The circuit includes a first multiplexer configured to selectively couple a current source to the bias input terminals of the magnetic sensors or to the bias input terminal of the diagnostic sensor and includes a second multiplexer configured to selectively couple the bias output terminals of the magnetic sensors or the bias output terminal of the diagnostic sensor to a first terminal of a switch. The circuit includes a third multiplexer configured to selectively couple the measurement terminals of the magnetic sensors or the measurement terminals of the diagnostic sensor to differential input terminals of an amplifier.

For triaxial magnetic detection data sequentially acquired as data points in a triaxial coordinate system, an offset calculation unit 30 calculates virtual data points P1′-P6′ by evenly parallel-translating each of data points P1-P7 so that a reference data point P7, for example, arbitrarily chosen from the data points P1-P7 coincides with an origin point O. A virtual offset point C′ for which the sum of the distances between the virtual data points P1′-P6′ and a curved surface H1 passing through the origin point O is minimized is then calculated. An offset value C for the magnetic detection data is then calculated by parallel-translating the virtual offset point C′ so as to restore the parallel-translated portion.

A system and method for calibrating rigid and non-rigid arrays of 3-axis magnetometers as disclosed. Such arrays might be used to analyze structures containing ferromagnetic material. The calibration determines scale factor and bias parameters of each magnetometer in the array, and the relative orientation and position of each magnetometer in the array. Once the parameters are determined, the actual magnetic field value at the magnetometer location can be simply related to magnetometer measurements. The method and system can be used to calibrate an array of 3-axis magnetometers in aggregate as opposed to individual magnetometers. This is critical in large arrays to increasing reproducibility of the calibration procedure and decreasing time required to complete calibration procedure.

Head-mounted augmented reality (AR) devices can track pose of a wearer's head to provide a three-dimensional virtual representation of objects in the wearer's environment. An electromagnetic (EM) tracking system can track head or body pose. A handheld user input device can include an EM emitter that generates an EM field, and the head-mounted AR device can include an EM sensor that senses the EM field. EM information from the sensor can be analyzed to determine location and/or orientation of the sensor and thereby the wearer's pose. An improved or optimized pose can be provided by reverse-estimating a reverse EM measurement matrix and optimizing the pose based on a comparison between the reverse EM measurement matrix and an EM measurement matrix measured by the EM sensor.

Disclosed is a method to remove distortion from a navigation system. The navigation system may be used to perform a procedure on a subject. The procedure may be any appropriate procedure. The navigation system may be used to account for the distortive effects of various conductive objects positioned near the subject on which the procedure is performed.