A system and method that can automatically select a frequency of a magnetic field in a magnetic tracking system. A magnetic tracking system emits an alternating magnetic field using a set of three frequencies. In the present approach, a transmitter is capable of generating multiple sets of three frequencies. A processor selects a first set of frequencies to use and causes the receiver to measure the amplitude of the magnetic field at those frequencies. In one embodiment, the frequency set having the lowest energy is selected. The processor then compares an estimated jitter at those frequencies to the actual jitter experienced using the frequencies. If the actual jitter exceeds the estimated jitter by a predetermined amount, the processor switches to a different set of frequencies and causes the receiver to measure the magnetic field at the new set of frequencies. The process may repeat using the additional sets of frequencies.

A method, device, and system for detecting a current leak in a traction power rail. Magnetic or electrical properties of the rail are measured. The measurements are performed using a rail instrument that senses the properties around the rail at various times while the instrument is being moved down the rail, such as using a cart or train. The rail instrument may be a flux concentrator or open Rogowski coil. The locations of the rail, about which the readings are taken by the rail instrument, may be determined and correlated with the measurements themselves. The method may comprise measuring the magnetic field of the rail along a length of the rail, and identifying a leak based on differences between the magnetic field measurements. The system may comprise a cart comprising the rail instrument and a location instrument.

A method, device, and system for detecting a current leak in a traction power rail. Magnetic or electrical properties of the rail are measured. The measurements are performed using a rail instrument that senses the properties around the rail at various times while the instrument is being moved down the rail, such as using a cart or train. The rail instrument may be a flux concentrator or open Rogowski coil. The locations of the rail, about which the readings are taken by the rail instrument, may be determined and correlated with the measurements themselves. The method may comprise measuring the magnetic field of the rail along a length of the rail, and identifying a leak based on differences between the magnetic field measurements. The system may comprise a cart comprising the rail instrument and a location instrument.

A magnetic field measurement system includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes a first feedback loop that includes a first low pass filter with a first cutoff frequency and a second feedback loop that includes a second low pass filter with a second cutoff frequency. The first and second feedback loops are configured to compensate for magnetic field variations having a frequency lower than the first or second cutoff frequency, respectively.

A magnetic field measurement system includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes a first feedback loop that includes a first low pass filter with a first cutoff frequency and a second feedback loop that includes a second low pass filter with a second cutoff frequency. The first and second feedback loops are configured to compensate for magnetic field variations having a frequency lower than the first or second cutoff frequency, respectively.

A method and apparatus for reducing magnetic tracking error in the position and orientation determined in a magnetic tracking system having a magnetic field generator. In some embodiments, the measured position and orientation of a sensor is compared to an expected theoretical position and orientation. Any error is assumed to be from “floor distortion,” i.e., eddy currents in the floor caused by the magnetic field generated by the magnetic field transmitter. The floor distortion is modeled as being caused by eddy currents caused by a second magnetic field transmitter that is a reflection of the actual transmitter. An algorithm iteratively searches over a parameter space to minimize the difference between the measured position and orientation and the theoretical position and orientation, and applies a correction to the measured position and orientation. The measurements and corrections of the position and orientation run in real-time with no additional hardware or calibration required.

Disclosed herein is a nano-magnetic-particle-imaging apparatus, including a measurement head including excitation and detection coils and accommodating a sample bed for a sample including nano magnetic particles; a gradient magnetic field generation unit for generating a magnetic field having a strength equal to or greater than that of the saturation magnetic field of the nano magnetic particles in a spacing area between identical magnetic poles facing each other and forming a field-free region in a portion thereof; a first driving unit for linearly moving the sample bed; a second driving unit for rotating the gradient magnetic field generation unit in a plane; a third driving unit for linearly reciprocating the gradient magnetic field generation unit; and a control unit for applying a signal to the excitation coil, controlling the driving units, and imaging 3D distribution of the nano magnetic particles based on a detection signal output from the detection coil.

A calibration device comprising: a plurality of magnetic sensors positioned at the calibration device, the plurality of magnetic sensors defining a space; a controller configured to be positioned in the space defined by the plurality of magnetic sensors, wherein the controller includes a magnetic transmitter; and one or more processors configured to: cause the magnetic transmitter to generate magnetic fields; receive signals from the plurality of magnetic sensors that are based on characteristics of the magnetic fields received at the plurality of magnetic sensors; calculate, based on the signals received from the plurality of magnetic sensors, positions and orientations of the plurality of magnetic sensors relative to a position and orientation of the magnetic transmitter; and determine whether the calculated positions and orientations of the plurality of magnetic sensors are within one or more threshold limits of known positions and orientations of the plurality of magnetic sensors.

An electromagnetic field sensor includes a conductor plate, a signal output terminal to output a potential difference between the conductor plate and the signal output terminal, and a linear conductor including a first end electrically connected to a plate face of the conductor plate and a second end opposite to the first end and provided with a signal output terminal. The electromagnetic field sensor includes a loop plane that is formed by the conductor plate and the linear conductor and orthogonal to a plate face of the conductor plate when viewed from the side.

An electromagnetic tracking system including a patient support element and an electromagnetic field generator. The patient support element is superposed relative to the electromagnetic field generator, and the electromagnetic field generator is selectively moveable relative to the patient support element.