Methods and systems for calibrating a sensor using a vector field

• US 20070124097A1
• Filed: 11/27/2006
• Published: 05/31/2007
• Est. Priority Date: 11/28/2005
• Status: Active Grant

• Current Assignee: IDHL Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Hillcrest Laboratories Incorporated (CEVA Incorporated)
• Inventors: Turner, Mark, Geck, Friedrich, Liberty, Matthew
• Granted Patent: US 7,719,261 B2
• Time in Patent Office: Days
• US Class Current: 702/116
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• 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
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry

Abstract

Systems and methods according to the present invention address these needs and others by providing a system for calibrating a sensor using a constant vector field.

Claims

1. A method for calibrating a sensor comprising the steps of:

placing the sensor in a cube;

rotating said cube between a plurality of different orientations;

collecting at least one reading from said sensor from each of said plurality of different orientations; and

calibrating said sensor using said collected readings.

2. The method of claim 1, wherein said sensor is a magnetometer.

3. The method of claim 1, further comprising the steps of:

placing said cube in a cube holder; and

rotating said cube between said plurality of different orientations within said cube holder.

4. The method of claim 3, wherein said step of rotating occurs according to a predetermined rotation sequence.

5. The method of claim 1, wherein said collected readings are processed through a sensor model.

6. The method of claim 3, wherein said sensor model is the following equation:

R_I*H_E=a_s*R*f(M/m_s), wherein a_s and m_s are arbitrary scaling vectors, M is the 3×

1 vector of said sensor measurement, R is a 3×

3 rotation matrix that includes rotation, scale and skew, R_I is a 3×

3 rotation matrix corresponding to a placement of said cube in said cube holder, H_E is a value of said vector, and f is a transformation function.

7. The method of claim 6, wherein H_E is represented in spherical coordinates.

8. The method of claim 1, wherein said step of collecting further comprises transmitting said at least one reading from said sensor from each of said plurality of different orientations to a computing device for processing.

9. The method of claim 8, wherein said step of calibrating said sensor using said collected readings further comprises receiving processed data from said computing device.

10. The method of claim 9, wherein said sensor is linked to said computing device for processing.

11. The method of claim 1, further comprising the step of calibrating the vector direction.

12. A system for calibrating a sensor comprising:

a sensor to be calibrated;

a cube within which said sensor is mounted; and

a cube holder on which said cube can be rotated between a plurality of measurement positions.

13. The system of claim 12, wherein said sensor is a magnetometer.

14. The system of claim 12, wherein said cube collects at least one reading from said sensor from each of said plurality of measurement positions.

15. The system of claim 12, wherein rotation occurs according to a predetermined rotation sequence.

16. The system of claim 12, wherein readings are collected at each one of said plurality of measurement positions by a sensor model.

17. The system of claim 12, wherein said sensor model is the following equation:

R_I*H_E=a_s*R*f(M/m_s), wherein a_s and m_s are arbitrary scaling vectors, M is the 3×

1 vector of said sensor measurement, R is a 3×

3 rotation matrix that includes rotation, scale and skew, R_I is a 3×

3 rotation matrix corresponding to a placement of said cube in said cube holder, H_E is a value of said vector, and f is a transformation function.

18. The system of claim 17, wherein H_E is represented in spherical coordinates.

19. The system of claim 14. wherein said cube transmits collected data to a computing device for processing.

20. The system of claim 19, wherein said sensor receives processed data from a computing device for calibration.

21. The system of claim 20, wherein said sensor is linked to said computing device.

22. The system of claim 12, wherein said sensor is calibrated for the vector direction.

23. A system for calibrating a sensor comprising:

means for placing the sensor in a cube;

means for rotating said cube between a plurality of different orientations;

means for collecting at least one reading from said sensor from each of said plurality of different orientations; and

means for calibrating said sensor using said collected readings.