Portable electronic device adapted to provide an improved attitude matrix

• US 8,688,403 B2
• Filed: 02/28/2011
• Issued: 04/01/2014
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Oka, Anand Ravindra, Almalki, Nazih, Snow, Christopher Harris
• Primary Examiner(s): Charioui, Mohamed
• Assistant Examiner(s): BLOSS, STEPHANIE E
• Application Number:
  US13/036,563
• Publication Number:
  US 20120221290A1
• Time in Patent Office: 1,128 Days
• Field of Search: 702/141, 702/93, 702/153, 702/150, 702/152, 702/92, 702/9
• US Class Current: 702/153
• CPC Class Codes: G01B 21/16 for measuring distance of clearance between spaced objects
• CPC Class Codes: G01C 19/00 Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
• CPC Class Codes: G06F 15/00 Digital computers in general details G06F1/00 – G06F13/00; Data processing equipment in general
• 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

According to one aspect, a method of determining an attitude matrix on a portable electronic device. The method includes determining a first attitude matrix gradient using data from at least one of an accelerometer and a magnetometer, determining a second attitude matrix gradient using data from a gyroscope, fusing the first attitude matrix gradient and the second attitude matrix gradient based on a mixing coefficient to generate a fused gradient, and based on the fused gradient, updating a fine attitude matrix for the portable electronic device.

Claims

1. A method of determining an attitude matrix on a portable electronic device, comprising:

determining a first attitude matrix gradient using data from at least one of an accelerometer and a magnetometer;

determining a second attitude matrix gradient using data from a gyroscope;

determining, on a processor, in real time or substantially real time, a mixing coefficient having a value between 0 and 1, the value of the mixing coefficient based on an acceleration and a magnetic field currently experienced by the portable electronic device;

fusing the first attitude matrix gradient and the second attitude matrix gradient based on a mixing coefficient to generate a fused gradient D according to;

D=β

(1−

α

)C+Δ

α

B

wherein C is the first attitude matrix, B is the second attitude matrix, β and

Δ

are first and second weighting parameters, and α

is the mixing coefficient; and

based on the fused gradient, updating a fine attitude matrix for the portable electronic device.

2. The method of claim 1, wherein the mixing coefficient is varied based on one or more factors to affect the relative importance of the first and second attitude matrix gradients on the fused gradient.

3. The method of claim 2, wherein data from one or more of the accelerometer, the magnetometer, and the gyroscope are used to adjust the mixing coefficient.

4. The method of claim 3, wherein the mixing coefficient is selected to reduce the relative importance of the first attitude matrix gradient when the accelerometer determines that the device is experiencing an acceleration substantially different from Earth'"'"'s gravity.

5. The method of claim 3, wherein the mixing coefficient is selected to reduce the relative importance of the first attitude matrix gradient when the magnetometer determines that the device is experiencing a magnetic field substantially different from the generally known local magnetic field.

6. The method of claim 3, wherein the mixing coefficient is selected to reduce the relative importance of the second attitude matrix gradient when the accelerometer determines that the device is experiencing an acceleration substantially similar to Earth'"'"'s gravity.

7. The method of claim 1, wherein the fused gradient is determined based on at least one weighting parameter selected to adjust the speed with which at least one of the first and second matrix gradients impact the fused gradient.

8. The method of claim 1, wherein the first attitude matrix gradient is determined based on using at least three local frame vectors to determine a coarse attitude matrix.

9. The method of claim 8, wherein an output of the gyroscope in a local frame of reference is converted to global gyroscope data in a global frame of reference by pre-multiplication of the raw output by the transpose of the current coarse attitude matrix, and subsequently the second attitude matrix gradient is determined by taking a cross product of the global gyroscope data with the transpose of a previous estimate of the fine attitude matrix.

10. The method of claim 1, wherein the first attitude matrix gradient comprises an accelerometer/magnetometer attitude matrix gradient, and the second attitude matrix gradient comprises a gyroscope attitude matrix gradient.

11. A portable electronic device, comprising:

a gyroscope for detecting the rotational velocity of the device;

at least one of an accelerometer for detecting the acceleration experienced by the device, and a magnetometer for determining the position and orientation of the device with respect to a magnetic field; and

at least one processor coupled with the gyroscope, the accelerometer and the magnetometer, the at least one processor adapted to;

determine a first attitude matrix gradient using data from at least one of the accelerometer and the magnetometer;

determine a second attitude matrix gradient using data from the gyroscope;

determine, in real time or substantially real time, a mixing coefficient having a value between 0 and 1, the value of the mixing coefficient based on an acceleration and a magnetic field currently experienced by the portable electronic device;

fuse the first attitude matrix gradient and second attitude matrix gradient based on a mixing coefficient to generate a fused gradient D according to

D=β

(1−

α

)C+Δ

α

B

wherein C is the first attitude matrix, B is the second attitude matrix, β and

Δ

are first and second weighting parameters, and α

is the mixing coefficient; and

based on the fused gradient, update a fine attitude matrix for the portable electronic device.

12. The device of claim 11, wherein the mixing coefficient is varied based on one or more factors to affect the relative importance of the first and second attitude matrix gradients on the fused gradient.

13. The device of claim 12, wherein data from one or more of the accelerometer, the magnetometer, and the gyroscope are used to adjust the mixing coefficient.

14. The device of claim 13, wherein the at least one processor is selected to select the mixing coefficient to reduce the relative importance of the first attitude matrix gradient when the accelerometer determines that the device is experiencing an acceleration substantially different from Earth'"'"'s gravity.

15. The device of claim 13, wherein the at least one processor is selected to reduce the relative importance of the first attitude matrix gradient when the magnetometer determines that the device is experiencing a magnetic field substantially different from the known local magnetic field.

16. The device of claim 13, wherein the at least one processor is selected to reduce the relative importance of the second attitude matrix gradient when the accelerometer determines that the device is experiencing an acceleration substantially similar to Earth'"'"'s gravity.

17. The device of claim 13, wherein the fused gradient is based on at least one weighting parameter selected to adjust the speed with which at least one of the first and second matrix gradients impacts the fused gradient.

18. The device of claim 11, wherein the at least one processor is adapted to determine the first attitude matrix gradient based on using at least three local frame vectors to determine a coarse attitude matrix.

19. The device of claim 18, wherein at least one processor is adapted to determine the second attitude matrix gradient by converting an output of the gyroscope in a local frame of reference to global gyroscope data in a global frame of reference by pre-multiplication of the raw output by the transpose of the current coarse attitude matrix, and subsequently determine the second attitude matrix gradient by taking a cross product of the global gyroscope data with the transpose of a previous estimate of the fine attitude matrix.

20. A method of determining an attitude matrix on a portable electronic device, comprising:

determining a first attitude matrix gradient using data from at least one of an accelerometer and an electronic compass;

determining a second attitude matrix gradient using data from a gyroscope;

determining, on a processor in real time or substantially real time, a mixing coefficient having a value between 0 and 1, the value of the mixing coefficient based on an acceleration and a magnetic field currently experienced by the portable electronic device;

fusing the first attitude matrix gradient and the second attitude matrix gradient based on a mixing coefficient to generate a fused gradient D according to

D=β

(1−

α

)C+Δ

α

B

wherein C is the first attitude matrix, B is the second attitude matrix, β and

Δ

are first and second weighting parameters, and α

is the mixing coefficient; and

based on the fused gradient, updating a fine attitude matrix for the portable electronic device.