Gaze tracking system, eye-tracking assembly and an associated method of calibration

• US 20050280603A1
• Filed: 08/23/2005
• Published: 12/22/2005
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: Carl J. Vorst, John H. Aughey, Michael V. Rohr, Steven D. Swaine
• Original Assignee: Carl J. Vorst, John H. Aughey, Michael V. Rohr, Steven D. Swaine
• Inventors: Vorst, Carl J., Swaine, Steven D., Aughey, John H., Rohr, Michael V.
• Granted Patent: US 7,130,447 B2
• Time in Patent Office: Days
• US Class Current: 345/8
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: G02B 2027/0138 comprising image capture systems, e.g. camera
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0187 slaved to motion of at least a part of the body of the user, e.g. head, eye
• CPC Class Codes: G02B 2027/0198 System for aligning or maintaining alignment of an image in a predetermined direction
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

A system for tracking a gaze of an operator includes a head-mounted eye tracking assembly, a head-mounted head tracking assembly and a processing element. The head-mounted eye tracking assembly comprises a visor having an arcuate shape including a concave surface and an opposed convex surface. The visor is capable of being disposed such that at least a portion of the visor is located outside a field of view of the operator. The head-mounted head tracking sensor is capable of repeatedly determining a position of the head to thereby track movement of the head. In this regard, each position of the head is associated with a position of the at least one eye. Thus, the processing element can repeatedly determine the gaze of the operator, based upon each position of the head and the associated position of the eyes, thereby tracking the gaze of the operator.

Claims

1. A method of calibrating a gaze tracking system relative to an object, wherein the gaze tracking system includes an eye tracking assembly capable of tracking movement of at least one eye of an operator and a head tracking sensor capable of tracking movement of a head of the operator, said method comprising:

repeatedly moving the head tracking sensor to a plurality of different positions;

measuring a position of the at least one eye and an angle offset of a line of sight of the at least one eye relative to a first reference point, and measuring the position of the head tracking sensor and an angle offset of the head tracking sensor relative to a second reference position, wherein measuring occurs for each of the plurality of different positions; and

calibrating the gaze tracking system based upon the measured positions of the at least one eye, the offset angles of the at least one eye, the positions of the head tracking sensor and the offset angles of the head tracking sensor relative to the second reference position.

2. A method according to claim 1, wherein the calibrating step comprises calibrating the gaze tracking system with an artificial neural network.

3. A method according to claim 1, wherein the calibrating step comprises calibrating the gaze tracking system according to an interpolation technique.

4. A method according to claim 1, further comprising aligning the line of sight of the at least one eye with the first reference point and setting a position of the head tracking sensor as the second reference position, wherein the aligning step occurs before moving the head tracking sensor.

5. A method according to claim 4, further comprising moving the first reference point to at least one additional position, wherein the aligning, moving and measuring steps occur for each additional position of the first reference point.

6. A calibration system for calibrating a gaze tracking system relative to an object, wherein the gaze tracking system includes an eye tracking assembly capable of tracking movement of at least one eye of an operator and a head tracking sensor capable of tracking movement of a head of the operator, said calibration system comprising:

a processing element capable of repeatedly prompting movement of the head tracking sensor to a plurality of different positions,

wherein the processing element is capable of measuring a position of the at least one eye and an angle offset of a line of sight of the at least one eye relative to a first reference point, and measuring the position of the head tracking sensor and an angle offset of the head tracking sensor relative to a second reference position, wherein measuring occurs for each of the plurality of different positions, and

wherein the processing element is capable of calibrating the gaze tracking system based upon the measured positions of the at least one eye, the offset angles of the at least one eye, the positions of the head tracking sensor and the offset angles of the head tracking sensor relative to the second reference position.

7. A calibration system according to claim 6, wherein the processing element is capable of calibrating the gaze tracking system with an artificial neural network.

8. A calibration system according to claim 6, wherein the processing element is capable of calibrating the gaze tracking system according to an interpolation technique.

9. A calibration system according to claim 6, wherein the processing element is further capable of prompting alignment of the line of sight of the at least one eye with the first reference point and setting a position of the head tracking sensor as the second reference position, wherein the processing element is capable of prompting alignment of the line of sight before prompting movement of the head tracking sensor.

10. A calibration system according to claim 9, wherein the processing element is further capable of moving the first reference point to at least one additional position, wherein the processing element is capable of directing alignment of the line of sight and movement of the head tracking sensor, and capable of measuring a position, for each additional position of the first reference point.

11. A method for tracking movement of at least one eye of an operator, said method comprising:

providing an eye tracking assembly, the eye tracking assembly comprising;

an at least partially reflective visor capable of being disposed such that the visor is capable of reflecting an image of the at least one eye, wherein the visor is capable of being disposed such that at least a portion of the visor is located outside a field of view of the operator;

an image capture device disposed in optical communication with the visor; and

a lens disposed in an optical path of the image capture device, the image capture device having an effective focus based upon an optical power of the visor and an optical power of the lens; and

tracking movement of the at least one eye at the image capture device based upon the image of the at least one eye reflected by the visor.

12. A method according to claim 11, wherein the providing step comprises providing an eye tracking assembly including a visor having a concave surface and an opposed convex surface, the concave surface of the visor including a reflective coating.

13. A method according to claim 11, wherein the providing step comprises providing an eye tracking assembly further comprising an illuminator capable of illuminating the at least one eye.

14. A method according to claim 13, wherein the providing step comprises providing an eye tracking assembly further comprising an illuminator capable of illuminating the at least one eye with infrared light.

15. A method according to claim 11, wherein the providing step comprises providing an eye tracking assembly including an image capture device located outside the field of view of the operator.