GYROSCOPE STABILIZER FILTER

• US 20150226578A1
• Filed: 04/30/2014
• Published: 08/13/2015
• Est. Priority Date: 05/02/2013
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings SAS (InterDigital, Inc.)
• Original Assignee: Hillcrest Laboratories Incorporated (CEVA Incorporated)
• Inventors: LIBERTY, Matthew G., COOK, Bryan A., LI, Yun
• Granted Patent: US 9,482,554 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A63F 13/25 Output arrangements for video game devices
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A method, a filtering module, and a computer-readable medium are configured to filter measurements acquired in a sensor reference system. Filtered measurements of motion sensors and a magnetometer attached to the device may then be used to determine orientation of a device in a non-inertial reference system. The measurements are filtered in a reference system, whose position relative to the sensor system can be calculated, and in which gravity and Earth'"'"'s magnetic field have substantially constant direction and magnitude during the filtering window.

Claims

1. A method for filtering a measurement acquired in a sensor reference system, the method comprising:

determining a transformation from a sensor reference system to a gyroscope reference system;

rotating at least one measurement from the sensor reference system to the gyroscope reference system using the transformation;

filtering the rotated at least one measurement to remove at least a high-frequency time-dependent portion thereof; and

rotating the filtered at least one measurement back into the sensor reference system.

2. The method of claim 1, wherein the transformation is determined using a previous angular position of the gyroscope reference system in the sensor reference system, and an angular velocity measured in the sensor reference system.

3. The method of claim 2, wherein the angular velocity and the at least one measurement are acquired by sensors attached to a device, the sensor reference system being associated to a rigid body of the device.

4. The method of claim 3, wherein the method is performed by a data processing unit of the device.

5. The method of claim 3, wherein the angular velocity is measured by a 3D gyroscope.

6. The method of claim 3, wherein the device is a mobile communication device.

7. The method of claim 1, wherein the at least one measurement corresponds to an acceleration and/or to a magnetic field.

8. The method of claim 7, wherein the magnetic field is measured using a 3D magnetometer.

9. The method of claim 7, wherein the acceleration is measured using a 3D accelerometer.

10. The method of claim 7, wherein one of the at least one measurement corresponds to acceleration and the filtered time-dependent portion thereof is used to estimate a current linear position of the device.

11. The method of claim 7, further comprising:

applying a sensor fusion method to determine a current orientation of the sensor reference system relative to an Earth-type reference system, using the filtered rotated at least one measurement as an input.

12. The method of claim 11, further comprising:

displaying an image for a gaming system user according to the current orientation.

13. The method of claim 11, further comprising:

determining a position of a cursor on a display according to the current orientation.

14. The method of claim 11, wherein the method is performed by a processor of an apparatus controlled based on the current orientation.

15. The method of claim 1, wherein the transformation determined as a quaternion representing angular position of the gyroscope reference system relative to the sensor reference system.

16. A computer readable medium storing executable codes which when performed by a computer make the computer perform a method for filtering a measurement acquired in a sensor reference system, the method comprising:

determining a transformation from a sensor reference system to a gyroscope reference system using a previous angular position of the gyroscope reference system in the sensor reference system, and an angular velocity measured in the sensor reference system;

rotating at least one measurement from the sensor reference system to the gyroscope reference system using the transformation;

filtering the rotated at least one measurement to remove at least a high-frequency time-dependent portion thereof; and

rotating the filtered at least one measurement back into the sensor reference system.

17. A filtering module, comprising:

a first input configured to receive a current value of an angular velocity of a device;

a second input configured to receive a measurement of an acceleration or a magnetic field from sensors mounted on the device;

an integration unit configured to receive the angular velocity and to determine a transformation to be applied to the received measurement;

a first rotation unit configured to receive the transformation and to apply the transformation to the received measurement;

a filter configured to modify the transformed measurement, so that the modified measurement to correspond to a substantially time-independent portion; and

a second rotation unit configured to receive the transformation, to apply an inverse of the transformation to the modified measurement and to output a result thereof.

18. A method for filtering a measurement acquired in a sensor reference system, the method comprising:

determining a transformation from a sensor reference system to an estimated Earth-type reference system using a fusion quaternion determined by applying a fusion method to a set of measurements previously acquired in the sensor reference system and integrating an angular velocity measured in the sensor reference system;

rotating at least one measurement from the sensor reference system to the estimated Earth-type reference system using the transformation;

filtering the rotated at least one measurement to remove a high-frequency time-dependent portion thereof; and

rotating the filtered at least one measurement back into the sensor reference system.