Head tracking

Patent metadata

Field	Value
Publication number	US-10015620-B2
Application number	US-201013147954-A
Country	US
Kind code	B2
Filing date	Feb 9, 2010
Priority date	Feb 13, 2009
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A head tracking system that determines a rotation angle of a head of a user with respect to a reference direction, dependent on a movement of a user including changes of place, position, and/or posture. The head tracking system includes a sensing device for measuring a head movement to provide a measure representing the head movement, and a processing circuit for deriving the rotation angle of the head of the user with respect to the reference direction from the measure. The reference direction is dependent on the movement of the user.

First claim

The invention claimed is:

1. A head tracking system comprising:
a sensing device configured to sense changes in a direction of a head of a user resulting in a value representing the sensed changes in the direction of the head; and
a processing circuit configured to
determine a reference direction of the head independent of an environment of the user by adaptively averaging the direction of the head during movement of the user, wherein the reference direction of the head is adapted to larger changes in the direction of the head faster than to relatively smaller changes in the direction of the head,
derive a rotation angle of the head with respect to the reference direction from the value,

receive audio including an audio scene from an audio source,
adapt the received audio scene based on the derived rotation angle of the head, and
render an audio signal based on the received audio and the adapted audio scene.

2. The head tracking system as claimed in claim 1 , wherein the averaging of the direction of the head of the user is taken over a sliding time window.

3. The head tracking system as claimed in claim 1 , wherein the sensing device comprises at least one accelerometer for deriving an angular speed of a rotation of the head of the user based on centrifugal force caused by the rotation.

4. The head tracking system as claimed in claim 3 , wherein the processing circuit is configured to derive an average direction of the head of the user from the angular speed of the head of the user.

5. The head tracking system as claimed in claim 4 , wherein the average direction of the head is determined as an average of the rotation angle over an adaptive period of time Ta, wherein the larger changes in the direction of the head result in the adaptive period of time Ta being shorter than the relatively smaller changes in the direction of the head.

6. The head tracking system as claimed in claim 1 , wherein a direction of a body of the user during the movement of the user is used as the reference direction.

7. The head tracking system as claimed in claim 6 , wherein the movement of the user is determined as movement of a reference point located on the body of the user.

8. The head tracking system as claimed in claim 7 , wherein the sensing device comprises a magnetic transmitter attached to the reference point and a magnetic sensor attached to the head of the user for receiving a magnetic field transmitted by the magnetic transmitter.

9. The head tracking system as claimed in claim 8 , wherein the magnetic transmitter comprises two orthogonal coils placed in a transverse plane, wherein the magnetic field created by each of the two orthogonal coils is modulated with different modulation frequencies.

10. The head tracking system as claimed in claim 8 , wherein the magnetic sensor comprises a coil, wherein the coil is placed in a predetermined direction of the head of the user.

11. The head tracking system as claimed in claim 8 , wherein the processing circuit is configured to derive rotation angle of the head of the user from the magnetic field received by the magnetic sensor.

12. A head tracking method comprising acts of:
sensing changes in a direction of a head of a user resulting in a value representing the sensed changes in the direction of the head;
determining a reference direction of the head independent of an environment of the user by adaptively averaging the direction of the head during movement of the user, wherein the reference direction of the head is adapted to larger changes in the direction of the head faster than to relatively smaller changes in the direction of the head;
deriving a rotation angle of the head of the user with respect to the reference direction from the value;
receiving audio including an audio scene;
adapting the received audio scene based on the derived rotation angle of the head; and
rendering an audio signal based on the received audio and the adapted audio scene.

13. An audio reproduction system for audio scene reproduction over headphone comprising:
a headphone for reproducing an audio scene;
a rendering processor for rendering the audio scene to be reproduced;
a head tracking system including
a sensor configured to sense changes in a direction of a head of a user resulting in a value representing the sensed changes in the direction of the head, and
a processor for determining a reference direction of the head independent of an environment of the user by adaptively averaging the direction of the head during movement of the user, wherein the reference direction of the head is adapted to larger changes in the direction of the head faster than to relatively smaller changes in the direction of the head, and for determining a rotation angle of the head of the user with respect to the reference direction from the value,

wherein the rendering processor is configured to:
receive audio including an audio scene from an audio source,
adapt the received audio scene based on the derived rotation angle of the head, and
provide an audio signal based on the received audio and the adapted audio scene to the headphone for reproduction.

14. The audio reproduction system as claimed in claim 13 , wherein head tracking system is at least partially integrated with the headphone.

15. The head tracking system as claimed in claim 1 , wherein the adaptive averaging adapts the reference direction slower to small movements of the head of the user than to larger movements of the head of the user.

16. The head tracking system as claimed in claim 1 , wherein the adaptive averaging adapts the reference direction faster to large changes in the rotational angle of the head of the user than to smaller changes in the rotational angle of the head of the user.

Assignees

• Dillen Paulus Henricus Antonius
• Oomen Arnoldus Werner Johannes
• Schuijers Erik Gosuinus Petrus
• Koninklijke Philips Nv

Inventors

• Dillen Paulus Henricus Antonius
• Oomen Arnoldus Werner Johannes
• Schuijers Erik Gosuinus Petrus

Classifications

• H04S7/304 Primary

  For headphones · CPC title