A method for compensating a magnetic heading includes one or more of obtaining a magnetic heading from a magnetic instrument deployed with an apparatus, determining location data for the apparatus, determining local field data based on the location data, obtaining a magnetic profile for the magnetic instrument deployed with the apparatus, and compensating the magnetic heading based the magnetic profile. For example, the magnetic profile may be responsive to perturbation of the local geomagnetic field by the apparatus, so that the compensated heading is more responsive to a directional heading of the apparatus, when deployed in the geomagnetic field. An apparatus for performing the method is also described, along with another method for calibrating the magnetic instrument when deployed with the apparatus, in order to generate the magnetic profile.

Methods of calibrating strapdown heading sensors and strapdown heading sensors are provided. The methods include compensating raw sensor data generated by sensors of an uncalibrated strapdown heading sensor to compensate for errors in an instrument frame of the strapdown heading sensor. The strapdown heading sensor is put in a target apparatus and output data is compensated to compensate for errors in an apparatus frame relative to the instrument frame. The strapdown heading sensors include a housing and a compass module having a first sensor configured to detect a magnetic field of the Earth and a second sensor configured to detect a gravitational force of the Earth. The first sensor and the second sensor are each passively isolated from bending and/or flexing of the housing such that an alignment between the first sensor and the second sensor is not disturbed due to the bending and/or flexing.

Methods of calibrating strapdown heading sensors and strapdown heading sensors are provided. The methods include compensating raw sensor data generated by sensors of an uncalibrated strapdown heading sensor to compensate for errors in an instrument frame of the strapdown heading sensor. The strapdown heading sensor is put in a target apparatus and output data is compensated to compensate for errors in an apparatus frame relative to the instrument frame. The strapdown heading sensors include a housing and a compass module having a first sensor configured to detect a magnetic field of the Earth and a second sensor configured to detect a gravitational force of the Earth. The first sensor and the second sensor are each passively isolated from bending and/or flexing of the housing such that an alignment between the first sensor and the second sensor is not disturbed due to the bending and/or flexing.

The present method includes a first step of obtaining first values of compensation coefficients for magnetic anomalies of the magnetometer, and a second step of in-flight refining including: a) an acquisition of a plurality of magnetic field vector values and associated aircraft attitude angle values; b) a calculation of a magnetic heading as a function of the first values of the compensation coefficients and values of magnetic field vector; c) a recursive calculation of a slope coefficient, as a function of a difference in heading between the calculated magnetic heading and a reference magnetic heading, and of values for aircraft attitude angles; and d) a calculation of a value of compensation coefficient for vertical magnetic anomalies using a vertical bias estimator as a function of the slope coefficient, aircraft attitude angle values, and local terrestrial magnetic field values.

Calibrating a pressure sensor of a mobile device incudes determining an absolute calibration value used to calibrate pressure measurements by a pressure sensor of a mobile device; determining a first revisit zone as a first location to which the mobile device repeatedly returns; determining first and second calibrations for first and second visits to the first revisit zone; determining a first relative calibration adjustment value based on a difference between the first and second calibrations; determining an adjusted absolute calibration value based on a sum of the absolute calibration value and the first relative calibration adjustment value; and estimating an altitude of the mobile device based on a pressure measurement by the pressure sensor and the adjusted absolute calibration value.

Calibrating a pressure sensor of a mobile device incudes determining an absolute calibration value used to calibrate pressure measurements by a pressure sensor of a mobile device; determining a first revisit zone as a first location to which the mobile device repeatedly returns; determining first and second calibrations for first and second visits to the first revisit zone; determining a first relative calibration adjustment value based on a difference between the first and second calibrations; determining an adjusted absolute calibration value based on a sum of the absolute calibration value and the first relative calibration adjustment value; and estimating an altitude of the mobile device based on a pressure measurement by the pressure sensor and the adjusted absolute calibration value.

A method for determining a flight path for an aircraft system, for example an unmanned aircraft system (UAS) comprises analysing an intensity map relating to a three dimensional space. The intensity map comprises an array of voxels, each voxel defining a volume in the three dimensional space, and each voxel having a related traffic intensity value based on historical flight data through that voxel. The method comprises determining a probability of an encounter for a preferred flight path between a start point and an end point via one or more voxels in the three dimensional space, based on traffic intensity values of the one or more voxels along the preferred flight path. The preferred flight path is selected if the probability of encounter is less than a first threshold value.

An increase in power consumption involved in calibration for calibrating an offset of a geomagnetism sensor is suppressed. An electronic device performs calibration of an output error of the geomagnetism sensor so that the geomagnetism sensor can output more accurate geomagnetism data based on angular speed data output by a gyro sensor. The electronic device controls turning ON/OFF of the gyro sensor. The electronic device determines whether or not calibration of the geomagnetism sensor is necessary. When it is determined that calibration of the geomagnetism sensor is unnecessary, the electronic device performs a control operation to turn OFF the gyro sensor.

An increase in power consumption involved in calibration for calibrating an offset of a geomagnetism sensor is suppressed. An electronic device performs calibration of an output error of the geomagnetism sensor so that the geomagnetism sensor can output more accurate geomagnetism data based on angular speed data output by a gyro sensor. The electronic device controls turning ON/OFF of the gyro sensor. The electronic device determines whether or not calibration of the geomagnetism sensor is necessary. When it is determined that calibration of the geomagnetism sensor is unnecessary, the electronic device performs a control operation to turn OFF the gyro sensor.

Calibrating a pressure sensor of a mobile device incudes determining an absolute calibration value used to calibrate pressure measurements by a pressure sensor of a mobile device; determining a first revisit zone as a first location to which the mobile device repeatedly returns; determining first and second calibrations for first and second visits to the first revisit zone; determining a first relative calibration adjustment value based on a difference between the first and second calibrations; determining an adjusted absolute calibration value based on a sum of the absolute calibration value and the first relative calibration adjustment value; and estimating an altitude of the mobile device based on a pressure measurement by the pressure sensor and the adjusted absolute calibration value.