Methods, apparatus and systems for gyroscope scale calibration

Abstract

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.

What is claimed is: 
     
         1 - 30 . (canceled) 
     
     
         31 . A method, implemented in a device having a sensor, to calibrate a scale of the sensor, comprising:
 receiving, by the device, a first input indicating that the device is in a first angular position, as a start position;   providing, by the device, a first indication that the device is ready to be moved to another position or a final position;   measuring, by the device, a plurality of output values of the sensor, after the first indication is provided;   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;   estimating, by the device, the scale of the sensor using the plurality of output values measured while the device moved between the start position and the final position; and   providing, by the device, a second indication of whether the estimate of the scale of the sensor is within a predefined threshold.   
     
     
         32 . The method of  claim 31 , wherein the providing of the first indication includes presenting, via a display or a light, the first indication that the device is ready to be moved to the other position or the final position, as an indication that the device is ready for calibration. 
     
     
         33 . The method of  claim 32 , wherein the providing of the second indication includes presenting, via the display or the light, the second indication indicating whether the sensor satisfies the predefined threshold, as a calibration threshold. 
     
     
         34 . The method of  claim 31 , wherein the estimating of the scale of the sensor includes:
 averaging one or more output values of the sensor taken while the device is at the start position;   determining, by the device, a zero rate offset (ZRO) from the averaged one or more output values of the sensor taken while the device is at the start position; and   compensating, by the device, for the ZRO in the estimation of the scale of the sensor.   
     
     
         35 . The method of  claim 31 , wherein the start position is a position such that the device is in a docking station. 
     
     
         36 . The method of  claim 35 , further comprising undocking the device such that the device is undocked from the docking station while the device was moving between the start position and the final position. 
     
     
         37 . The method of  claim 36 , further comprising redocking the device such that estimating of the scale of the sensor is conditioned on the device being redocked in the docking station. 
     
     
         38 . The method of  claim 31 , further comprising:
 sending, by the device, any of: (1) data associated with the output values of the sensor measured while the device moved between the start position and the final position; (2) estimation information in accordance with the estimating of the scale of the sensor; (3) one or more error codes indicating a type of error associated with a scale estimation operation; or (4) a calibration record.   
     
     
         39 . A device, having a sensor, comprising:
 an interface configured to:
 receive a first input indicating that the device is in a first angular position, as a start position, and 
 provide a first indication that the device is ready to be moved to another position or a final position; and 
   a processor configured to:
 measure a plurality of output values of the sensor, after the first indication is provided, and 
 estimate the scale of the sensor using the plurality of output values measured while the device moved between the start position and the final position, 
   wherein the 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 the final position, and 
 provide a second indication indicating whether the estimate of the scale of the sensor is within a predefined threshold. 
   
     
     
         40 . The device of  claim 39 , wherein the interface includes a display or light configured to:
 present, to an external entity, the first indication that the device is ready to be moved to the other position or the final position, as an indication that the device is ready for calibration; and   present, to the external entity, the second indication indicating whether the estimate of the scale of the sensor is within the predefined threshold.   
     
     
         41 . The device of  claim 39 , wherein the processor is configured to:
 average one or more output values taken while the device is at the start position;   determine a zero rate offset (ZRO) from the averaged one or more output values taken while the device is at the start position; and   compensate for the ZRO in the estimation of the scale of the sensor.   
     
     
         42 . The device of  claim 39 , wherein the interface includes a transmit unit configured to send any of: (1) data associated with the output values measured while the device moved between the start position and the final position; (2) estimation information in accordance with the estimation of the scale of the sensor; (3) one or more error codes indicating a type of error associated with a scale estimation operation; or (4) a calibration record. 
     
     
         43 . The device of  claim 39 , wherein the start position is a position such that the device is in a docking station. 
     
     
         44 . The device of  claim 43 , further comprising;
 a motor unit configured to:
 undock the device from the docking station; 
 move the device between the start position and the final position; and 
 redock the device in the docking station. 
   
     
     
         45 . The device of  claim 44 , wherein the processor is configured to estimate the scale of the sensor on condition that the device is redocked in the docking station. 
     
     
         46 . A device having a sensor, comprising:
 a transmit/receive unit configured to:
 send a first indication that the device is ready to be moved to another position or a final position after being positioned in a first angular position, as a start position, and 
 receive a first input indicating that the device is in a second, preconfigured angular position, relative to the start position, as the final position; and 
   a processor configured to estimate the scale of the sensor using a plurality of output values of the sensor measured while the device moved between the start position and the final position.   
     
     
         47 . The device of  claim 46 , wherein the transmit/receive unit is configured to provide a second indication of whether the estimate of the scale of the sensor is within a predefined threshold. 
     
     
         48 . The device of  claim 46 , wherein the transmit/receive unit is configured to receive another input indicating that the device is in the first angular position. 
     
     
         49 . The device of  claim 44 , wherein the processor is configured to measure a plurality of output values of the sensor, after the first indication is sent.