Position tracking system

• US 8,031,227 B2
• Filed: 03/07/2006
• Issued: 10/04/2011
• Est. Priority Date: 03/07/2005
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Ye, Cang, Neal, Homer A., Herr, Jeremy
• Primary Examiner(s): Ye; Lin
• Assistant Examiner(s): HSU, AMY R
• Application Number:
  US11/369,572
• Publication Number:
  US 20060197840A1
• Time in Patent Office: 2,037 Days
• Field of Search: 348/169
• US Class Current: 348/169
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

A position tracking system includes an infrared-sensitive device, such as an infrared camera that generates signals in response to detected infrared light in a field of view of the infrared-sensitive device. A processor is responsive to the signals generated by the infrared-sensitive device for determining a position of the detected infrared light. The processor also generates tilt and pan signals based on the position of the detected infrared light. A tilt and pan mechanism moves a visible-light video camera in response to the tilt and pan signals from the processor. The active infrared light-emitting device includes a loop having at least two infrared light-emitting elements disposed along the loop, on opposite sides of the loop. A control box is disposed in the loop and is in electrical communication with the infrared light-emitting elements. When the loop is disposed around an object that rotates relative to the infrared-sensitive device, a constantly unimpeded viewing channel is provided between the infrared-sensitive device and at least one of the elements due to the positioning of the elements. The position information obtained from the infrared-sensitive device is used to direct a visible-light camera to track the active infrared light-emitting device in a manner similar to that performed by a human camera operator.

Claims

1. A position tracking system comprising:

an infrared-sensitive device that generates signals in response to detected infrared light in a field of view of said infrared-sensitive device;

a processor responsive to said signals generated by said infrared-sensitive device for determining a position of the detected infrared light with said processor generating tilt and pan signals based on said position, wherein said processor determines said position of the detected infrared light in a two-dimensional coordinate image plane based on said signals and determines a distance of said position from a set point in the two-dimensional coordinate image plane;

a visible-light video camera for recording visible light within the same field of view as the infrared-sensitive device;

a tilt and pan mechanism that moves said visible-light video camera in response to said tilt and pan signals from said processor; and

an active infrared light-emitting device including a loop having at least two infrared light-emitting elements disposed along said loop on opposite sides thereof and a control box disposed in said loop in electrical communication with said infrared light-emitting elements for providing a constantly unimpeded viewing channel between said infrared-sensitive device and at least one of said elements when said loop is disposed around an object that rotates relative to said infrared-sensitive device;

wherein said loop is further defined as necklace or accessory to be placed around a person'"'"'s waist, neck, or other appendage.

2. A position tracking system as set forth in claim 1 wherein said loop is further defined as a closed loop with said control box disposed in said closed loop in electrical communication with said infrared light-emitting elements.

3. A position tracking system as set forth in claim 2 wherein at least one of said infrared light-emitting elements is disposed opposite said control box across said loop.

4. A position tracking system as set forth in claim 3 wherein infrared light-emitting elements are spaced at intervals of less than or equal to two inches along said loop.

5. A position tracking system as set forth in claim 1 wherein said infrared light-emitting elements are further defined as infrared light-emitting diodes having a width of less than 5 mm, a length of less than 5 mm, and a depth of less than 3 mm.

6. A position tracking system as set forth in claim 1 wherein said loop is further defined as an open loop having a first end and a second end adapted for connection to each other with said control box disposed in said open loop adjacent to one of said ends and in electrical communication with said infrared light-emitting elements.

7. A position tracking system as set forth in claim 1 wherein said processor generates tilt and pan signals based on the distance of said position from said set point.

8. A position tracking system as set forth in claim 1 further comprising a software package that synchronizes a recording from said visible-light video camera and slides from a presentation.

9. A position tracking system as set forth in claim 1 wherein the processor determines a point to track between the infrared light-emitting elements that is indicative of the position of the detected infrared light.

10. A position tracking system as set forth in claim 9 wherein the point to track is a center point within a ring of the detected infrared lights.

11. A method of tracking with a position tracking system including an infrared-sensitive device, a processor, a visible-light video camera, a tilt and pan mechanism, and an active infrared light-emitting device, said method comprising the steps of:

generating signals with the infrared-sensitive device in response to detected infrared light in a field of view of the device;

transmitting the signals to the processor;

determining a position of the detected infrared light in a two-dimensional coordinate image plane based on the signals with the processor;

determining a distance of the position from a set point in the two-dimensional coordinate image plane with the processor;

generating tilt and pan signals with the processor based on the position;

transmitting the tilt and pan signals to the tilt and pan mechanism;

moving the visible-light video camera with the tilt and pan mechanism in response to the tilt and pan signals from the processor;

placing the active infrared light-emitting device on an object that rotates relative to the infrared-sensitive device;

emitting infrared light from the active infrared light-emitting device including a loop having at least two infrared light-emitting elements disposed along the loop on opposite sides thereof, wherein said loop is further defined as necklace or accessory to be placed around a person'"'"'s waist, neck, or other appendage; and

providing a constantly unimpeded viewing channel between the infrared-sensitive device and at least one of the elements.

12. A method as set forth in claim 11 further comprising the step of simultaneously pulsating the infrared light emitted from each the elements at a predetermined frequency.

13. A method as set forth in claim 11 further comprising the step of synchronizing a recording from the visible-light video camera and slides from a presentation.

14. A method as set forth in claim 11 wherein the step of generating tilt and pan signals is further defined as generating the tilt and pan signals with the processor based on the distance of the position from the set point.

15. A method as set forth in claim 11 wherein the processor determines a point to track between the infrared light-emitting elements that is indicative of the position of the detected infrared light.

16. A method as set forth in claim 15 wherein the point to track is a center point within a ring of the detected infrared lights.