A compass includes a magnetic sensing element in the form of a coil surrounding magnetic material. Electric current is supplied to the coil in opposite directions, depending on the state of switches operated at times T.sub.0, for a first direction, and T.sub.5, for a reverse current direction. A voltmeter measures voltages across the coil, namely at least V.sub.1 at time T.sub.1, after T.sub.0, and V.sub.2 at time T.sub.2, after T.sub.5, with T.sub.1−T.sub.0=T.sub.2−T.sub.5=predetermined ΔT. A processor indicates V.sub.1−V.sub.2, the magnitude and sign of which indicate the strength and direction of the earth's magnetic field respectively.

A compass includes a magnetic sensing element in the form of a coil surrounding magnetic material. Electric current is supplied to the coil in opposite directions, depending on the state of switches operated at times T.sub.0, for a first direction, and T.sub.5, for a reverse current direction. A voltmeter measures voltages across the coil, namely at least V.sub.1 at time T.sub.1, after T.sub.0, and V.sub.2 at time T.sub.2, after T.sub.5, with T.sub.1−T.sub.0=T.sub.2−T.sub.5=predetermined ΔT. A processor indicates V.sub.1−V.sub.2, the magnitude and sign of which indicate the strength and direction of the earth's magnetic field respectively.

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.

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.

Methods and systems estimate calibration errors of magnetic sensor measurements collected at mobile devices. Each measurement is associated with a location of one of the mobile devices and has a calibration error. Data from the sensor measurements is partitioned into sets. Each set is associated with a respective calibration error associated with the measurements that generated the data in the set. Pairs of data items are identified, where each pair includes a data item from a first of the sets corresponding to a measurement, associated with a first location, that generated the data in the first set, and a data item from a second of the sets corresponding to a measurement, associated with a second location that is approximately the same as the first location, that generated the data in the first set. The calibration error associated with each of the sets is estimated based in part on the pairs.

A method of controlling a gimbal includes receiving angular velocity information transmitted by a somatosensory controller, the angular velocity information including an angular velocity of the somatosensory controller in a geodetic coordinate system, determining a target attitude of the gimbal according to the angular velocity information, and controlling the gimbal according to the target attitude.

A method of controlling a gimbal includes receiving angular velocity information transmitted by a somatosensory controller, the angular velocity information including an angular velocity of the somatosensory controller in a geodetic coordinate system, determining a target attitude of the gimbal according to the angular velocity information, and controlling the gimbal according to the target attitude.

Disclosed are an electronic device for compensating for geomagnetic sensing data and a method for controlling the same. According to an embodiment of the disclosure, an electronic device may include a processor configured to store, in a memory, a temperature of each of a plurality of heating areas and a variation in a geomagnetic value sensed by a geomagnetic sensor, perform linear fitting using the temperature and the variation in the geomagnetic value, compute an error between the variation in the geomagnetic value and an estimated value for the variation in the geomagnetic value, based on a result of the linear fitting, determine a scheme for compensating for the geomagnetic value based on the computed error, and compensate for the geomagnetic value sensed by the geomagnetic sensor using the determined scheme when a variation in temperature is detected for at least one heating area in the plurality of heating areas.

An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process. Directional sensing systems can be calibrated accurately during a period when the Earth's magnetic field changes rapidly.

An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process. Directional sensing systems can be calibrated accurately during a period when the Earth's magnetic field changes rapidly.