Calibrating Inertial Sensors Using an Image

Abstract

A method is provided for calibrating an inertial sensing unit of a device utilizing a vision sensing unit integral to the device. The method includes receiving inertial sensing input data from the inertial sensing unit, receiving vision sensing input data from the vision unit, and determining when the received vision sensing input data represents a predetermined input state of the vision sensing unit. The method includes estimating an error value in the inertial sensing input data received from the inertial sensing unit based on the received vision sensing input data upon determination that the received vision sensing input data represents the predetermined vision sensing input state. The method further includes adjusting first subsequent received inertial sensing input data from the inertial sensing unit based on the estimated error value, thereby calibrating the inertial sensing unit.

1 . A method comprising:
 during a session in which a first application is open on a computing device:
 (a) receiving, from a first inertial sensing unit integral to the computing device, first inertial data indicating movement of the wearable device during a period of time; 
 (b) receiving, from a second inertial sensing unit integral to the computing device, second inertial data indicating the movement of the computing device during the period of time; 
 (c) determining, based on a comparison of the first inertial data to the second inertial data, an error value in the first inertial data; 
 (d) based on the estimated error value, determining an inertial-data adjustment for subsequently received inertial data from the first inertial sensing unit; and 
 (e) storing the inertial-data adjustment in a memory of the computing device; 
   subsequently initiating a session of a second application on the computing device, wherein the second application utilizes inertial data from the first inertial sensing unit; and   applying the stored inertial-data adjustment to at least some inertial data generated by the inertial sensing unit during the session of the second application.   
     
     
         2 . The method of  claim 1 , further comprising, in response to initiating the session of the second application that utilizes inertial data, retrieving the inertial-data adjustment from memory and applying the inertial-data adjustment to at least some inertial data generated by the inertial sensing unit during the session of the second application. 
     
     
         3 . The method of  claim 1 , further comprising:
 determining when the second inertial data represents a predetermined input state of the second inertial sensing unit and responsively performing (c) to (e).   
     
     
         4 . The method of  claim 1 , wherein the second inertial data comprises-input image data received from an image sensing unit integral to the wearable device, the method further comprising:
 determining when the received input image data represents a predetermined input state of the image sensing unit and responsively performing (c) to (e).   
     
     
         5 . The method of  claim 4 , wherein determining when the received input image data represents the predetermined image sensing input state comprises:
 determining when the predetermined image sensing input state corresponds to a predetermined input data threshold.   
     
     
         6 . The method of  claim 5 , wherein the predetermined input data threshold is indicative of a substantial stillness of the input image data. 
     
     
         7 . The method of  claim 5 , wherein the predetermined input data threshold is indicative of a predetermined movement threshold of the device. 
     
     
         8 . The method of  claim 1 , wherein the computing device comprises a wearable computing device. 
     
     
         9 . The method of  claim 1 , wherein the computing device comprises a mobile computing device. 
     
     
         10 . The method of  claim 1 , wherein the computing device comprises a handheld computing device. 
     
     
         11 . The method of  claim 1 , wherein the inertial sensing unit is one of a gyroscope, an accelerometer, and a magnetometer. 
     
     
         12 . The method of  claim 1 , wherein the computing system comprises:
 a memory unit storing program instructions executable to perform the method; and   a processor unit operatively coupled to the memory unit, the inertial sensing unit, and the image sensing unit, and configured to execute the method.   
     
     
         13 . A method comprising:
 determining that no application running on a computing device is utilizing data generated by a first inertial sensing unit integral to the computing device; and   in response to determining that no application is utilizing data generated by the inertial sensing unit:
 (a) operating the first inertial sensing unit to receive first inertial data indicating movement of the computing device; 
 (b) operating a second inertial sensing unit to receive second inertial data indicating movement of the computing device; 
 (c) determining, based on a comparison of the first inertial data to the second inertial data, an error value in the first inertial data; and 
 (d) adjusting subsequently received inertial data from the first inertial sensing unit based on the estimated error value. 
   
     
     
         14 . The method of  claim 13 , further comprising:
 determining when the second inertial data represents a predetermined input state of the second inertial sensing unit and responsively performing (c) and (d).   
     
     
         15 . The method of  claim 13 , wherein the second inertial data comprises-input image data received from an image sensing unit integral to the wearable device, the method further comprising:
 determining when the received input image data represents a predetermined input state of the image sensing unit and responsively performing (c) and (d).   
     
     
         16 . The method of  claim 13 , wherein the computing device comprises a wearable computing device. 
     
     
         17 . The method of  claim 13 , wherein the computing device comprises a mobile computing device. 
     
     
         18 . A non-transitory computer readable storage medium comprising program instructions that cause a computing system to perform functions comprising:
 during a session in which a first application is open on a computing device:
 (a) receiving, from a first inertial sensing unit integral to the computing device, first inertial data indicating movement of the wearable device during a period of time; 
 (b) receiving, from a second inertial sensing unit integral to the computing device, second inertial data indicating the movement of the computing device during the period of time; 
 (c) determining, based on a comparison of the first inertial data to the second inertial data, an error value in the first inertial data; 
 (d) based on the estimated error value, determining an inertial-data adjustment for subsequently received inertial data from the first inertial sensing unit; and 
 (e) storing the inertial-data adjustment in a memory of the computing device; 
   subsequently initiating a session of a second application on the computing device, wherein the second application utilizes inertial data from the first inertial sensing unit; and   applying the stored inertial-data adjustment to at least some inertial data generated by the inertial sensing unit during the session of the second application.   
     
     
         19 . The transitory computer readable storage medium of  claim 18 , wherein the second inertial data comprises-input image data received from an image sensing unit integral to the wearable device, further comprising program instructions that cause the computing system to perform functions comprising:
 determining when the received input image data represents a predetermined input state of the image sensing unit and responsively performing (c) to (e).   
     
     
         20 . The transitory computer readable storage medium of  claim 19 , wherein determining when the received input image data represents the predetermined image sensing input state comprises:
 determining when the predetermined image sensing input state corresponds to a predetermined input data threshold.