Methods, apparatus and systems for gyroscope scale calibration
Methods, apparatus, and systems for estimating and calibrating a gyroscope's scale using a magnetometer mounted on the same device by rotating the device about an axis multiple times; and, during the first rotation, storing the magnetometer magnetic field reading and a heading (from integration of the gyroscope readings) at each of a plurality of angular reference points; then, during each subsequent rotation, determining magnetometer/gyroscope-heading output pairs for which the magnetometer output matches the magnetometer reading corresponding to one of the reference points, thereby indicating that the device has reached the same heading as the matching reference point; then, for each matching output sample pair, using that magnetometer/gyroscope-heading output sample pair to update the gyroscope scale factor for the corresponding angular reference point; and averaging those scale estimates to generate a final gyroscope scale factor estimate.
1. A method, implemented in a device having a gyroscope, to calibrate a gyroscope scale, comprising:
receiving, by the device, a first input indicating that the device is in a first angular position, as a start position to estimate the gyroscope scale;
starting an integration period on a condition that the first input is received and the device is ready for calibration;
presenting, by the device to an external entity, a first indication that the device is ready to be moved to another position or a final position, as an indication that the device is ready for the calibration;
sampling, by the device, a set of gyroscope outputs during the integration period;
receiving, by the device, a second input indicating that the device is in a second, preconfigured angular position, relative to the start position, as the final position;
ending the integration period, on a condition that the second input is received;
estimating, by the device, the gyroscope scale using samples of the set of gyroscope outputs sampled during the integration period; and
presenting, by the device to the external entity, a second indication of whether the estimate of gyroscope scale is within a threshold of a reference gyroscope scale.
2. The method of claim 1 , wherein the estimating of the gyroscope scale includes:
averaging one or more samples taken while the device is at the start position;
determining, by the device, a zero rate offset (ZRO) from the averaged one or more samples taken while the device is at the start position; and
compensating, by the device, for the ZRO in the estimation of the gyroscope scale.
3. The method of claim 1 , wherein the start position is a position such that the device is in a docking station.
4. The method of claim 3 , further comprising undocking the device such that the device is undocked from the docking station during the integration period.
5. The method of claim 4 , further comprising redocking the device such that the ending of the integration period is further conditioned on the device being redocked in the docking station.
6. The method of claim 1 , further comprising:
sending, by the device, any of: (1) data associated with the samples sampled during the integration period; (2) estimation information in accordance with the estimating of the gyroscope scale; (3) error codes indicating a type of error associated with a gyroscope scale estimation operation; or (4) a calibration record.
7. A method, implemented in a device having a gyroscope, to calibrate a gyroscope scale, comprising:
determining, by the device, that the device is in a first angular position, as a start position;
starting an integration period based on the determination that the device is in the start position and the device is ready for calibration;
presenting, by the device to an external entity, a first indication that the device is ready to be moved to another position or the final position, as an indication that the device is ready for the calibration;
sampling, by the device a set of gyroscope outputs during the integration period;
determining, by the device, that the device is in a second, preconfigured angular position, relative to the start position, as the final position based on samples taken from the gyroscope and/or an accelerometer;
ending the integration period based on the determination that the device is in the final position;
estimating, by the device, the gyroscope scale using samples of the set of gyroscope outputs sampled during the integration period; and
presenting, by the device to the external entity, a second indication of whether the estimated gyroscope scale is within a threshold of a reference gyroscope scale.
8. The method of claim 7 , wherein the determining that the device is in the start position includes determining that the device is in the start position based on samples from the gyroscope and/or the accelerometer.
9. The method of claim 8 , further comprising
receiving, by the device, user input; and
configuring, by the device, to be in a calibration mode based on the received user input.
10. A device having a gyroscope to calibrate a gyroscope scale, comprising:
a user interface configured to receive a first input indicating that the device is in a first angular position, as a start position to estimate the gyroscope scale;
a processor configured to:
start an integration period on a condition that the first input is received and the device is ready for calibration, and
sample a set of gyroscope outputs during the integration period,
wherein:
the user interface is configured to receive a second input indicating that the device is in a second, preconfigured angular position, relative to the start position, as a final position,
the processor is configured to:
end the integration period, on a condition that the second input is received, and
estimate the gyroscope scale using samples of the set of gyroscope outputs sampled during the integration period; and
a display or light configured to:
present, to an external entity, a first indication that the device is ready to be moved to another position or the final position, as an indication that the device is ready for the calibration; and
present to the external entity, a second indication of whether the estimate of gyroscope scale is within a threshold of a reference gyroscope scale.
11. The device of claim 10 , wherein the processor is configured to:
average one or more samples taken while the device is at the start position;
determine a zero rate offset (ZRO) from the averaged one or more samples taken while the device is at the start position; and
compensate for the ZRO in the estimation of the gyroscope scale.
12. The device of claim 10 , further comprising:
a transmit unit configured to send any of: (1) data associated with the samples sampled during the integration period; (2) estimation information in accordance with the estimation of the gyroscope scale; (3) error codes indicating a type of error associated with a gyroscope scale estimation operation; or (4) a calibration record.