System and method for determining an attitude of a device undergoing dynamic acceleration

• US 9,152,249 B2
• Filed: 10/31/2013
• Issued: 10/06/2015
• Est. Priority Date: 10/20/2008
• Status: Active Grant

• Current Assignee: Sensor Platforms, Incorporated (Knowles Corporation)
• Original Assignee: Sensor Platforms, Incorporated (Knowles Corporation)
• Inventors: Shaw, Kevin A., Chen, Ian
• Primary Examiner(s): Tzeng, Fred
• Application Number:
  US14/069,318
• Publication Number:
  US 20140139432A1
• Time in Patent Office: 705 Days
• Field of Search: 345/158, 345/157
• US Class Current: 1/1
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors

Abstract

A system and a method for determining an attitude of a device undergoing dynamic acceleration is presented. A first attitude measurement is calculated based on a magnetic field measurement received from a magnetometer of the device and a first acceleration measurement received from a first accelerometer of the device. A second attitude measurement is calculated based on the magnetic field measurement received from the magnetometer of the device and a second acceleration measurement received from a second accelerometer of the device. A correction factor is calculated based at least in part on a difference of the first attitude measurement and the second attitude measurement. The correction factor is then applied to the first attitude measurement to produce a corrected attitude measurement for the device.

Claims

1. A method, comprising:

at a respective computer system having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective computer system to perform the method, the method comprising;

obtaining a first acceleration measurement received from a first accelerometer of a device, wherein the first acceleration measurement corresponds to respective movement of the device;

obtaining a second acceleration measurement received from a second accelerometer of the device, wherein the second acceleration measurement corresponds to the respective movement of the device and the first accelerometer is spaced apart from the second accelerometer in the device by an accelerometer offset distance;

obtaining a pivot distance that corresponds to distance between the device and a pivot origin for the respective movement; and

determining an attitude measurement for the device based on the first acceleration measurement, the second acceleration measurement, the pivot distance and the accelerometer offset distance.

2. The method of claim 1, wherein the first accelerometer and the second accelerometer are spaced apart from each other by the accelerometer offset distance on a rigid body.

3. The method of claim 1, including:

determining a preliminary attitude of the device based on sensor measurements from a set of one or more sensors that includes the first accelerometer and the second accelerometer;

calculating a correction factor that is based on the accelerometer offset distance and the pivot distance; and

determining the attitude measurement based on the preliminary attitude of the device and the correction factor.

4. The method of claim 1, wherein the correction factor is the ratio of the accelerometer offset distance and the pivot distance.

5. The method of claim 1, wherein obtaining the pivot distance includes:

determining a pivot origin based on sensor measurements obtained during a plurality of measurement epochs; and

determining the pivot distance based on the pivot origin.

6. The method of claim 5, wherein determining the pivot origin includes determining whether movement of the device corresponds to movement of a user'"'"'s wrist, movement of the user'"'"'s elbow, or movement of the user'"'"'s shoulder.

7. The method of claim 1, wherein the first accelerometer is selected from the group consisting of:

a 2-axis accelerometer that measures a magnitude and a direction of an acceleration force in two dimensions; and

a 3-axis accelerometer that measures a magnitude and a direction of an acceleration force in three dimensions.

8. The method of claim 7, wherein the second accelerometer is selected from the group consisting of:

a 2-axis accelerometer that measures a magnitude and a direction of an acceleration force in two dimensions; and

a 3-axis accelerometer that measures a magnitude and a direction of an acceleration force in three dimensions.

9. A computer system comprising:

one or more processors;

memory; and

one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions to;

obtaining a first acceleration measurement received from a first accelerometer of a device, wherein the first acceleration measurement corresponds to respective movement of the device;

obtaining a second acceleration measurement received from a second accelerometer of the device, wherein the second acceleration measurement corresponds to the respective movement of the device and the first accelerometer is spaced apart from the second accelerometer in the device by an accelerometer offset distance;

obtaining a pivot distance that corresponds to distance between the device and a pivot origin for the respective movement; and

determining an attitude measurement for the device based on the first acceleration measurement, the second acceleration measurement, the pivot distance and the accelerometer offset distance.

10. The computer system of claim 9, wherein the first accelerometer and the second accelerometer are spaced apart from each other by the accelerometer offset distance on a rigid body.

11. The computer system of claim 9, including instructions for:

determining a preliminary attitude of the device based on sensor measurements from a set of one or more sensors that includes the first accelerometer and the second accelerometer;

calculating a correction factor that is based on the accelerometer offset distance and the pivot distance; and

determining the attitude measurement based on the preliminary attitude of the device and the correction factor.

12. The computer system of claim 9, wherein the correction factor is the ratio of the accelerometer offset distance and the pivot distance.

13. The computer system of claim 9, wherein obtaining the pivot distance includes:

determining a pivot origin based on sensor measurements obtained during a plurality of measurement epochs; and

determining the pivot distance based on the pivot origin.

14. The computer system of claim 13, wherein determining the pivot origin includes determining whether movement of the device corresponds to movement of a user'"'"'s wrist, movement of the user'"'"'s elbow, or movement of the user'"'"'s shoulder.

15. A non-transitory computer readable storage medium storing one or more programs configured for execution by one or more processors of a computer system, the one or more programs comprising instructions to:

obtain a first acceleration measurement received from a first accelerometer of a device, wherein the first acceleration measurement corresponds to respective movement of the device;

obtain a second acceleration measurement received from a second accelerometer of the device, wherein the second acceleration measurement corresponds to the respective movement of the device and the first accelerometer is spaced apart from the second accelerometer in the device by an accelerometer offset distance;

obtain a pivot distance that corresponds to distance between the device and a pivot origin for the respective movement; and

determine an attitude measurement for the device based on the first acceleration measurement, the second acceleration measurement, the pivot distance and the accelerometer offset distance.

16. The non-transitory computer readable storage medium of claim 15, wherein the first accelerometer and the second accelerometer are spaced apart from each other by the accelerometer offset distance on a rigid body.

17. The non-transitory computer readable storage medium of claim 15, including instructions which, when executed, cause the computer system to:

determine a preliminary attitude of the device based on sensor measurements from a set of one or more sensors that includes the first accelerometer and the second accelerometer;

calculate a correction factor that is based on the accelerometer offset distance and the pivot distance; and

determine the attitude measurement based on the preliminary attitude of the device and the correction factor.

18. The non-transitory computer readable storage medium of claim 15, wherein the correction factor is the ratio of the accelerometer offset distance and the pivot distance.

19. The non-transitory computer readable storage medium of claim 15, wherein obtaining the pivot distance includes:

determining a pivot origin based on sensor measurements obtained during a plurality of measurement epochs; and

determining the pivot distance based on the pivot origin.

20. The non-transitory computer readable storage medium of claim 19, wherein determining the pivot origin includes determining whether movement of the device corresponds to movement of a user'"'"'s wrist, movement of the user'"'"'s elbow, or movement of the user'"'"'s shoulder.