Mobile object image tracking apparatus and method

• US 8,243,142 B2
• Filed: 11/05/2008
• Issued: 08/14/2012
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakamura, Hiroaki
• Primary Examiner(s): Chan, Wing
• Assistant Examiner(s): Yi, David X
• Application Number:
  US12/265,017
• Publication Number:
  US 20090115850A1
• Time in Patent Office: 1,378 Days
• Field of Search: 348/169, 382/103
• US Class Current: 348/169
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: H04N 23/695 Control of camera direction for changing a field of view, e.g. pan, tilt or based on tracking of objects

Abstract

A mobile object image tracking apparatus includes at least one unit rotating about at least one axis, a camera sensor photographing a mobile object to acquire image data, a unit detecting a tracking error as a tracking error detection value, a unit detecting an angle of the rotary unit, a unit estimating the tracking error as a tracking error estimation value, a unit selecting the tracking error detection value when the mobile object falls within the field of view, and selecting the tracking error estimation value when the mobile object falls outside the field of view, a unit computing an angular velocity instruction value used to drive the rotating unit to track the mobile object, a unit detecting an angular velocity of the rotary unit, and a unit controlling the rotating unit to make zero a difference between the angular velocity instruction value and the angular velocity.

Claims

1. A mobile object image tracking apparatus comprising:

at least one rotary unit configured to rotate about at least one axis;

a camera sensor configured to photograph a mobile object to acquire image data, the camera sensor being supported by the rotary unit;

a first detection unit configured to detect a tracking error as a tracking error detection value, based on the image data, the tracking error being a deviation from a center of a field of view of the camera sensor;

a second detection unit configured to detect an angle of the rotary unit;

an estimation unit configured to estimate the tracking error as a tracking error estimation value, using the angle and a temporal differentiation value of the angle;

a selection unit configured to select the tracking error detection value when the mobile object falls within the field of view, and to select the tracking error estimation value when the mobile object falls outside the field of view;

wherein the selection unit compares the tracking error detection value with the tracking error estimation value, and adjusts the tracking error estimation value to match an amplitude of the tracking error estimation value with an amplitude of the tracking error detection value;

a computation unit configured to compute an angular velocity instruction value used to drive the rotary unit to track the mobile object, based on the angle and a selected one of the tracking error detection value and the tracking error estimation value;

a third detection unit configured to detect an angular velocity of the rotary unit; and

a control unit configured to control the rotary unit to make zero a difference between the angular velocity instruction value and the angular velocity.

2. The apparatus according to claim 1, wherein the estimation unit acquires the tracking error estimation value, using, as the temporal differentiation value, an angular velocity dimension value obtained by signal processing of data related to the angle, and also using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

3. The apparatus according to claim 2, wherein the selection unit compares the tracking error detection value with the tracking error estimation value, and adjusts the tracking error estimation value to match an amplitude of the tracking error estimation value with an amplitude of the tracking error detection value.

4. The apparatus according to claim 2, wherein the computation unit computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

5. The apparatus according to claim 2, wherein the computation unit computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

6. The apparatus according to claim 1, wherein the computation unit computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

7. The apparatus according to claim 1, wherein the computation unit computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

8. The apparatus according to claim 1, wherein the computation unit computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

9. The apparatus according to claim 1, wherein the computation unit computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

10. A mobile object image tracking method comprising:

preparing at least one rotary unit configured to rotate about at least one axis;

preparing a camera sensor configured to photograph a mobile object to acquire image data, the camera sensor being supported by the rotary unit;

detecting a tracking error as a tracking error detection value, based on the image data, the tracking error being a deviation from a center of a field of view of the camera sensor;

detecting an angle of the rotary unit;

estimating the tracking error as a tracking error estimation value, using the angle and a temporal differentiation value of the angle;

selecting the tracking error detection value when the mobile object falls within the field of view, and to select the tracking error estimation value when the mobile object falls outside the field of view;

wherein selecting the tracking error detection compares the tracking error detection value with the tracking error estimation value, and adjusts the tracking error estimation value to match an amplitude of the tracking error estimation value with an amplitude of the tracking error detection value;

computing an angular velocity instruction value used to drive the rotary unit to track the mobile object, based on the angle and a selected one of the tracking error detection value and the tracking error estimation value;

detecting an angular velocity of the rotary unit; and

controlling the rotary unit to make zero a difference between the angular velocity instruction value and the angular velocity.

11. The method according to claim 10, wherein estimating the tracking error acquires the tracking error estimation value, using, as the temporal differentiation value, an angular velocity dimension value obtained by signal processing of data related to the angle, and also using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

12. The method according to claim 11, wherein selecting the tracking error detection compares the tracking error detection value with the tracking error estimation value, and adjusts the tracking error estimation value to match an amplitude of the tracking error estimation value with an amplitude of the tracking error detection value.

13. The method according to claim 11, wherein computing the angular velocity instruction value computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

14. The method according to claim 11, wherein computing the angular velocity instruction value computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

15. The method according to claim 10, wherein computing the angular velocity instruction value computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

16. The method according to claim 10, wherein computing the angular velocity instruction value computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.

17. The method according to claim 10, wherein computing the angular velocity instruction value computes the angular velocity instruction using the tracking error estimation value, during a time when the tracking error detection value related to the image data acquired by the camera sensor is not updated.

18. The method according to claim 10, wherein computing the angular velocity instruction value computes the angular velocity instruction value using a relationship between the tracking error, the angle of the rotary unit, and the angular velocity of the rotary unit.