Ultrasonic camera tracking system and associated methods

• US 8,249,298 B2
• Filed: 10/15/2007
• Issued: 08/21/2012
• Est. Priority Date: 10/19/2006
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Polycom Incorporated (HP Inc.)
• Inventors: Saleh, Youssef, Chu, Peter, Feng, Jinwei, Nimri, Alain
• Primary Examiner(s): Bella, Matthew
• Assistant Examiner(s): Bitar, Nancy
• Application Number:
  US11/872,303
• Publication Number:
  US 20080095401A1
• Time in Patent Office: 1,772 Days
• Field of Search: 382/100, 382/102, 382/103, 348/14.09, 348/169, 348/16, 348/14.16, 348/14.08, 704/246, 704/218, 704/270, 359/296, 313/478, 313/474
• US Class Current: 382/103
• CPC Class Codes: G01S 3/808 using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 5/22 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence
• CPC Class Codes: H04N 7/15 Conference systems

Abstract

A camera tracking system includes a controllable camera, an array of microphones, and a controller. The microphones are positioned adjacent the controllable camera and are at least responsive to ultrasound emitted from a source. The microphones may additionally be capable of responding to sound in the audible spectrum. The controller receives ultrasound signals communicated from the microphones in response to ultrasound emitted from the source and processes the ultrasound signals to determine an at least approximate location of the source. Then, the controller sends one or more command signals to the controllable camera to direct at least approximately at the determined location of the source. The camera tracking system tracks the source as it moves and continues to emit ultrasound. The source can be an emitter pack having one or more ultrasonic transducers that produce tones that sweep form about 24-kHz to about 40-kHz.

Claims

1. A camera tracking apparatus, comprising:

a first source emitting ultrasound and being portable with a first subject to be tracked;

a controllable camera;

a plurality of receivers being stationary with respect to the controllable camera and the first source and being at least responsive to ultrasound; and

a controller communicatively coupled to the controllable camera and the receivers, the controller configured to;

receive ultrasound signals communicated from the receivers in response to the ultrasound emitted from the first source,

process the ultrasound signals to determine an at least approximate location of the first source, and

control the controllable camera to direct at least approximately at the determined location of the first source while the receivers are stationary.

2. The apparatus of claim 1, wherein to control the controllable camera, the controller commands the controllable camera to perform one or more of:

tilt, pan, or zoom at least approximately to the determined location of the first source.

3. The apparatus of claim 1, wherein each of the receivers comprise a microphone having a substantially flat frequency response within a range of about 24-kHz to about 40-kHz.

4. The apparatus of claim 3, wherein the ultrasound emitted from the first source comprises a tone sweeping in a range between about 24-kHz to about 40-kHz.

5. The apparatus of claim 3, wherein each of the microphones further comprises a frequency response within an audible range.

6. The apparatus of claim 1, wherein the first source comprises a portable emitter having one or more ultrasonic transducers.

7. The apparatus of claim 1, wherein to process the ultrasound signals, the controller is configured to pre-process the ultrasound signals to remove portions of the ultrasound signals caused by reflection.

8. The apparatus of claim 1, wherein to pre-process the ultrasound signals to remove portions of the ultrasound signals caused by reflection, the controller is configured to:

down sample the ultrasound signals,

filter the down sampled signals to substantial impulses, and

zero portions of the filtered signals to remove the portions of the ultrasound

signals caused by reflection.

9. The apparatus of claim 1, wherein at least two of the receivers are positioned along an axis with respect to the first source, and wherein to process the ultrasound signals to determine the at least approximate location of the first source, the controller is configured to:

calculate an approximate location of the first source along the axis using differences in the ultrasound signals between the at least two receivers, and

determine a variable for controlling the controllable camera based on the approximate location along the axis.

10. The apparatus of claim 1, further comprising memory storing a plurality of variables for candidate locations, the controller communicatively coupled to the memory and using the variables to process the ultrasound signals and determine the at least approximate location of the first source.

11. The apparatus of claim 1, wherein the first source has a first ultrasonic transducer positionable on one side of the first subject tracked by the camera and has a second ultrasonic transducer positionable on an opposite side of the first subject, whereby the first and second ultrasonic transducers enable the receivers to receive ultrasound when the first subject is oriented with either side relative to the receivers.

12. The apparatus claim 1, wherein the first source comprises at least one radio frequency transmitter transmitting radio frequency signals, and wherein the controller is configured to use the radio frequency signals to determine a range of the first subject from the controllable camera.

13. The apparatus of claim 12, wherein the at least one radio frequency transmitter also transmits voice signals of the first subject to the controller.

14. The apparatus of claim 1, further comprising one or more second sources separate from the first source and emitting ultrasound, each of the second sources being portable with one or more second subjects to be tracked by the camera.

15. The apparatus of claim 14 wherein each of the first and second sources detects voice from its subject and transmits ultrasound when activated by the detected voice.

16. The apparatus of claim 15, wherein each of the first and second sources when activated transmits a signal to at least one of the other sources to stop emitting ultrasound.

17. The apparatus of claim 14, wherein each of the first and second sources transmits ultrasound in a separate detectable range from the other sources.

18. The apparatus of claim 14, wherein the controller is configured to control the camera to position each of the first and one or more second subjects in a viewable area of the camera for those first and one or more second sources emitting ultrasound signals at the same time.

22. The method of claim 14, wherein removing the portions of the ultrasound caused by reflection comprises:

down-sampling signals of the ultrasound at each of the separate channels;

filtering the down sampled signals to substantial impulses; and

zeroing portions of the filtered signals to remove the portions of the signals caused by reflection.

19. A camera tracking method, comprising:

emitting ultrasound with a first source being portable with a first subject to be tracked;

receiving the ultrasound with a plurality of separate channels, each of the separate channels associated with a receiver being stationary relative to the first source;

determining an at least approximate location of the first source by processing the ultrasound received with the separate channels; and

controlling a camera movable relative to the receivers to at least approximately direct at the determined location of the first source while the receivers are stationary.

20. The method of claim 19, wherein receiving ultrasound with the plurality of separate channels comprise responding to ultrasound in a range of about 20-kHz to about 40-kHz at each of the separate channels.

21. The method of claim 19, wherein processing the ultrasound received with the separate channels comprises removing portions of the ultrasound signals caused by reflection.

23. The method of claim 19, wherein determining the at least approximate location of the first source comprises calculating a variable for controlling the camera based on differences in ultrasound signals received by at least two of the separate channels arranged along an axis with respect to the first source.

24. A non-transitory program storage device, readable by a programmable control device, comprising instructions stored on the program storage device for causing the programmable control device to perform a camera tracking method, the method comprising:

emitting ultrasound with a first source being portable with a first subject to be tracked;

receiving the ultrasound with a plurality of separate channels, each of the separate channels associated with a receiver being stationary relative to the first source;

determining an at least approximate location of the first source by processing the ultrasound received with the separate channels; and

controlling a camera movable relative to the receivers to at least approximately direct at the determined location of the first source while the receivers are stationary.

25. A camera tracking system, comprising:

an emitter unit having at least one ultrasonic transducer emitting ultrasound and being portable to track a subject;

a moveable camera;

a plurality of microphones being stationary relative to the emitter unit and the movable camera and being capable of at least responding to ultrasound emitted by the at least one ultrasonic transducer; and

a control unit communicatively coupled to the moveable camera and the microphones, the control unit receiving ultrasound signals communicated from the microphones in response to ultrasound detected from the at least one ultrasonic transducer, the control unit processing the ultrasound signals to determine an at least approximate location of the at least one ultrasonic transducer and controlling the moveable camera to direct at least approximately at the determined location while the microphones are stationary.