Restoring and storing magnetometer calibration data
First Claim
1. A computer-implemented method, comprising:
- receiving a current reading from a magnetometer of a mobile device;
identifying historical data of readings previously calibrated using the mobile device, wherein each previously-calibrated reading includes an associated bias offset;
calculating multiple estimates of Earth'"'"'s current magnetic field by subtracting bias offsets for the previously-calibrated readings from the current reading;
determining a confidence of a match between at least one estimate of the multiple estimates of Earth'"'"'s current magnetic field and historical data, where the confidence is determined at least in part on historical data including magnitudes of Earth'"'"'s magnetic field for the previously-calibrated readings; and
if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field exceeds a threshold confidence level, calibrating the magnetometer with historical calibration data;
wherein the method is performed by one or more processors.
1 Assignment
0 Petitions
Accused Products
Abstract
Responsive to a recalibration trigger event, magnetometer data output by a magnetometer can be compared to historical magnetometer data previously output by the magnetometer. If a match is determined, a confidence of the match can be determined using theoretically constant data related to Earth'"'"'s magnetic field. The constant data can be calculated from the historical magnetometer data. If the confidence of the match exceeds a confidence threshold level, historical calibration data can be used to calibrate the magnetometer. If the confidence of the match does not exceed the confidence threshold level, a calibration procedure can be performed to generate new calibration data, and the new calibration data can be used to calibrate the magnetometer.
52 Citations
15 Claims
-
1. A computer-implemented method, comprising:
-
receiving a current reading from a magnetometer of a mobile device; identifying historical data of readings previously calibrated using the mobile device, wherein each previously-calibrated reading includes an associated bias offset; calculating multiple estimates of Earth'"'"'s current magnetic field by subtracting bias offsets for the previously-calibrated readings from the current reading; determining a confidence of a match between at least one estimate of the multiple estimates of Earth'"'"'s current magnetic field and historical data, where the confidence is determined at least in part on historical data including magnitudes of Earth'"'"'s magnetic field for the previously-calibrated readings; and if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field exceeds a threshold confidence level, calibrating the magnetometer with historical calibration data; wherein the method is performed by one or more processors. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. An apparatus, comprising:
-
a magnetometer; memory storing historical magnetometer data; and a processor coupled to the magnetometer and the memory, the processor configured for; receiving a current reading from a magnetometer of a mobile device; identifying historical data of readings previously calibrated using the apparatus, wherein each previously-calibrated reading includes an associated bias offset; calculating multiple estimates of Earth'"'"'s current magnetic field by subtracting bias offsets for the previously-calibrated readings from the current reading; determining a confidence of a match between at least one estimate of the multiple estimates of Earth'"'"'s current magnetic field and historical data including magnitudes of Earth'"'"'s magnetic field for the previously-calibrated readings; if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field exceeds a threshold confidence level, calibrating the magnetometer with historical calibration data; and if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field does not exceed the threshold confidence level, performing a calibration procedure to determine new calibration data. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by at least one processor, causes the processor to perform operations comprising:
-
receiving a current reading from a magnetometer of a mobile device; identifying historical data of readings previously calibrated using the mobile device, wherein each previously-calibrated reading includes an associated bias offset; calculating multiple estimates of Earth'"'"'s current magnetic field by subtracting bias offsets for the previously-calibrated readings from the current reading; determining a confidence of a match between at least one estimate of the multiple estimates of Earth'"'"'s current magnetic field and historical data including magnitudes of Earth'"'"'s magnetic field for the previously-calibrated readings; if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field exceeds a threshold confidence level, calibrating the magnetometer with historical calibration data; and if the confidence of the match for the at least one estimate of Earth'"'"'s current magnetic field does not exceed the threshold confidence level, performing a calibration procedure to determine new calibration data. - View Dependent Claims (14, 15)
-
Specification