A method of detecting a vibration comprises determining a vibration flag has been set during a running mode of the magnetic field sensor, remaining in the running mode until a predetermined number of vibration flags have been set, and entering a recalibration mode when the predetermined number of vibration flags have been set. A counter can be implemented for each of the plurality of vibration flags to determine if the predetermined number of vibration flags have been set.

Magnetic field components are measured at multiple longitudinal positions and used to calculate estimated longitudinal position and length of a transversely localized electric current segment flowing across a gap between conductive bodies. The apparatus can be used with a remelting furnace. The electrode and ingot act as the conductive bodies, and arcs, discharges, or slag currents are the current segments spanning the gap. Actuators for movable sensors can be coupled to the sensors in a servomechanism arrangement to move the sensors along with the moving gap. An actuator for moving one of the conductive bodies can be coupled to sensors in a servomechanism arrangement to maintain the gap distance within a selected range as the gap moves.

An illustrative system includes a sensor component and a controller conductively coupled by way of a first wire and a second wire in a twisted pair configuration. The controller includes a driver configured to drive the sensor component by way of the first and second wires with a drive current in accordance with a gain parameter and a control loop circuit. The control loop circuit is configured to receive a control signal representative of a target current value for the drive current, adjust the gain parameter based on a difference between the target current value and an actual current value of current that is actually being driven through the sensor component, and abstain from adjusting the gain parameter based on current capacitively coupled onto the first and second wires by an external electric field.

A magnetic sensor device comprises a substrate. A first magnetic sensor, a second magnetic sensor, and one or more inductors are disposed over the substrate and are controlled by a magnetic sensor controller having a control circuit. The control circuit is adapted for controlling the first magnetic sensor to measure magnetic fields under presence of a first set of magnetic fields, and for controlling the second magnetic sensor to measure magnetic fields under presence of a second set of magnetic fields generated by the inductors. The control circuit calculates a relative sensitivity matching value that converts magnetic field values measured by the second magnetic sensor to a comparable magnetic field value measured by the first magnetic sensor or vice versa. The control circuit is further adapted for correcting a measurement by the second magnetic sensor using the relative sensitivity matching value to produce a corrected measurement, and for calculating a magnetic field gradient by combining a measurement by the first magnetic sensor with the corrected measurement.

A marker detection device which detects a magnetic marker laid in a road by using a sensor unit in which a plurality of combinations of a magnetic sensor and a magnetic-field generation coil are arranged includes a storage part which stores characteristic information of each magnetic-field generation coil, an estimation part which estimates a magnetic differential value acting on the magnetic sensor due to a current differential value acting on the magnetic-field generation coil by referring to the characteristic information of each magnetic-field generation coil, and a calibration part which calibrates each magnetic sensor so as to enhance uniformity in sensitivity, which is a ratio between an output differential value of the magnetic sensor in accordance with a change of a current by the current differential value acting on the magnetic-field generation coil and the estimated magnetic differential value.

A method for calibrating a magnetic source of an electromagnetic tracking system for tracking a position and orientation of an object using an inertial motion unit (IMU) mounted to the magnetic source and aligned with the coil array of magnetic source. Pitch and rolls angles of the coil array are calibrated using the IMU.

A sensor configured to generate a sensor output signal at a sensor output coupled to a pull up voltage through a pull up resistor includes a sensing element configured to generate a sensing element output signal indicative of a sensed parameter and a processor responsive to the sensing element output signal and configured to generate a processor output signal indicative of the sensed parameter. A digital output controller is responsive to the processor output signal and to a digital feedback signal and is configured to generate a controller output signal. An analog output driver is responsive to the controller output signal and configured to generate the sensor output signal at a first predetermined level or at a second predetermined level and a feedback circuit coupled between the sensor output and the digital output controller is configured to generate the digital feedback signal in response to the sensor output signal.

A directional tool and method of surveying a wellbore with the directional tool in a borehole string. A first sensor of the directional tool is disposed in a non-homogeneous ambient magnetic field. A first applied magnetic field is applied to the first sensor. A first measurement is obtained at the first sensor while the first sensor is disposed within the non-homogeneous ambient magnetic field and with the first applied magnetic field applied. A second applied magnetic field is applied to the first sensor. A second measurement is obtained at the first sensor while the first sensor is disposed within the non-homogeneous ambient magnetic field and with the second applied magnetic field applied. The directional tool is calibrated based on the first and second measurement. A downhole survey measurement is obtained with the calibrated directional tool in the wellbore.

The present invention relates to a hall electromotive force signal detection circuit and a current sensor thereof each of which is able to achieve excellent wide-band characteristics and fast response as well as high accuracy. A difference calculation circuit samples a component synchronous with a chopper clock generated by a chopper clock generation circuit, out of an output voltage signal of a signal amplifier circuit, at a timing obtained from the chopper clock, so as to detect the component. An integrating circuit integrates an output from the difference calculation circuit in the time domain. An output voltage signal from the integrating circuit is fed back to a signal amplifier circuit via a third transconductance element.

Methods, apparatus, and systems directed to calibrating a magnetometer. Among such are methods that use only the horizontal components of magnetometer measurements. Then, planar calibrated magnetic field output measurements can be used in sensor fusion with data from gyroscope(s) and accelerometer(s). In other embodiments, heading information from the planar calibrated magnetic field is fused with the heading calculated from gyroscope integration. Other such methods include any of generating combined information including 6-axis fusion information and magnetometer information; accumulating values for any of a first matrix [T] and a first vector [U] according to the combined information; generating a second matrix [{circumflex over (K)}] according to any of a pseudo-inverse of the first matrix [T] and the first vector [U]; generating any of a scale and skew matrix and an offset according to the first matrix [{circumflex over (K)}]; and calibrating the magnetometer according to any of the scale and skew matrix and the offset.