Determining forward pointing direction of a handheld device

• US 10,120,463 B2
• Filed: 10/27/2017
• Issued: 11/06/2018
• Est. Priority Date: 06/03/2010
• Status: Active Grant

• Current Assignee: CEVA Technologies, Inc. (CEVA Incorporated)
• Original Assignee: IDHL Holdings, Inc. (InterDigital, Inc.)
• Inventors: Liberty, Matthew G., Cook, Bryan A.
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): Fernande, Benjamin Morales
• Application Number:
  US15/796,058
• Publication Number:
  US 20180046266A1
• Time in Patent Office: 375 Days
• Field of Search: None
• CPC Class Codes: G06F 17/16 Matrix or vector computation , e.g. matrix-matrix or matrix-vector multiplication, matrix factorization matrix transposition G06F7/78
• CPC Class Codes: G06F 2203/0384 Wireless input, i.e. hardware and software details of wireless interface arrangements for pointing devices
• 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
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 2201/32 Remote control based on movements, attitude of remote control device
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared
• CPC Class Codes: H04N 21/42204 User interfaces specially adapted for controlling a client device through a remote control device; Remote control devices therefor constructive details of casings for the remote control device H01H9/0235; user interfaces for controlling a tuning device of a television receiver through a remote control H03J9/00; remote control of peripheral devices connected to a television receiver through the remote control device of the television receiver H04B1/205
• CPC Class Codes: H04N 21/42222 Additional components integrated in the remote control device, e.g. timer, speaker, sensors for detecting position, direction or movement of the remote control, microphone or battery charging device

Abstract

A forward pointing direction associated with a handheld device is estimated or determined by, for example, calculating a center of rotation of the device. A resultant combined or selected bias estimate may then be used to compensate the biased output of the sensor in, e.g., a 3D pointing device.

Claims

1. An apparatus for determining a forward pointing direction of a device having a user interface, the apparatus comprising:

an accelerometer for sensing an acceleration of the device and outputting at least one acceleration output;

at least one sensor for sensing rotation of the device and outputting at least one angular velocity output; and

a processor configured to process the acceleration output and the at least one angular velocity output to calculate a center of rotation of the device and determine the forward pointing direction of the device based on the determined center of rotation of the device.

2. The apparatus of claim 1 wherein the processor determines the forward pointing direction of the device as the vector from the center of rotation to the device.

3. The device of claim 1 wherein the calculation of the center of rotation of the device is further based on a gravitational constant.

4. The apparatus of claim 3, wherein the calculation of the center of rotation of the device uses:

an angular velocity matrix based upon the angular velocity output;

an angular acceleration matrix based upon the angular velocity output;

a direction cosine matrix based upon the angular velocity matrix and the angular acceleration matrix for defining the device frame of reference relative to an earth frame of reference; and

a linear acceleration based on the acceleration output.

5. The apparatus of claim 1 wherein the processing comprises converting raw sensor data into International System (SI) unit data and wherein the SI unit data is filtered to remove undesirable sensor characteristics comprising at least one of variable bias offset, cross-axis effects, scale variations, non-linearities, temperature effects and aging effects.

6. The apparatus of claim 5 further comprising a radio frequency (RF) transmitter communicatively connected to the processing unit, wherein the RF transmitter is configured to transmit the forward pointing direction.

7. The apparatus of claim 1 wherein the at least one sensor is a rotational sensor.

8. The apparatus of claim 1 wherein the at least one sensor is a gyroscope.

9. The apparatus of claim 1 wherein said at least one sensor is a magnetometer.

10. The apparatus of claim 4 further comprising a magnetometer, wherein the processor is further configured to use the magnetometer to improve calculation of the direction cosine matrix.

11. The apparatus of claim 1 wherein the processor is further configured to adjust a position of an object on the user interface based on said calculation.

12. A method for determining a forward pointing direction of a device, the method comprising:

collecting data associated with the device'"'"'s acceleration and rotation while the device is in motion; and

calculating of a center of rotation of the device based on the collected data and determining the forward pointing direction of the device based on the calculated center of rotation of the device.

13. The method of claim 12 further comprising:

filtering the data to remove at least one sensor characteristic from a group of sensor characteristics comprising variable bias offset, cross-axis effects, scale variations, non-linearities, temperature effects and aging effects.

14. The method of claim 12 wherein the calculating of the center of rotation of the device comprises calculating:

15. The method of claim 14 wherein the ^bΩ

² is;

16. The method of claim 14 wherein the ^bΩ

² is;

17. The method of claim 14 wherein multiple calculations of the device'"'"'s center of rotation vector are combined to optimize the center of rotation vector calculation.

18. The method of claim 17 wherein the center of rotation vector calculation result is offset based on an offset value of an accelerometer, associated with the device, from a center of the device.

19. The method of claim 12 wherein the calculating a center of rotation of the device comprises calculating:

^bc=((^b{dot over (Ω

)}₂+^bΩ

₂²)−

(I+^bΩ

^TΔ

t)(^b{dot over (Ω

)}₁+^bΩ

₁²))<sup>−

1</sup>(^ba₂−

(I+^bΩ

^TΔ

t)^ba₁), where;

^bΩ

² is an angular acceleration matrix of a first sample associated with the device in a body frame of reference, ^bΩ

² is an angular acceleration matrix of a second sample associated with the device in a body frame of reference, ^bΩ

₁² is the square of the angular velocity matrix of the first sample associated with the device in the body frame of reference, ^bΩ

₂² is the square of the angular velocity matrix of the second sample associated with the device in the body frame of reference, ^ba₁ is a linear acceleration of the first sample associated with the device in the body frame of reference, ^ba₂ is a linear acceleration of the second sample associated with the device in the body frame of reference, ^bΩ

^T Δ

t is the average angular velocity between the first sample and the second sample and I is an identity matrix.

20. The method of claim 12 further comprising:

adjusting a position of an object on a user interface of the device based on said calculation.