Method and apparatus for automatically tracking a moving object

• US 6,507,366 B1
• Filed: 04/20/1998
• Issued: 01/14/2003
• Est. Priority Date: 04/16/1998
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Hee-Jong
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Villecco, John M.
• Application Number:
  US09/062,556
• Time in Patent Office: 1,730 Days
• Field of Search: 348/170, 348/358, 348/103, 348/345, 348/349, 348/211, 348/169, 348/352
• US Class Current: 348/352
• CPC Class Codes: G06T 7/223 using block-matching
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• 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
• CPC Class Codes: H04N 7/142 Constructional details of the terminal equipment, e.g. arrangements of the camera and the display

Abstract

An apparatus and method for automatically tracking an object is provided. The apparatus for performing the method includes a camera having a zoom lens, an automatic focus lens, and a charge coupled device for converting an image of an object input via the lens into electrical signals. The camera is mounted on a camera supporter to rotate the camera around a first axis and the axis perpendicular to the first axis. The supporter includes holes and sensors for detecting the rotational limit of the camera in the horizontal and vertical directions. A pan/tilt controller detects a motion vector of the object, and controls the camera to move in the direction and degree corresponding to the detected motion vector. A zoom focus controller performs a zooming operation to expand an object search region of the camera whenever the camera reaches the limit of the rotational range in at least one direction, and adjusts an automatic focusing lens. A system controller connected to the pan/tilt controller and zoom/focus controller initializes a camera in order to automatically track a moving object and controls the operations sequence of each functional block.

Claims

1. An apparatus for automatically tracking a moving object, the automatic tracking apparatus comprising:

a camera including a zoom lens and an automatic focus lens, for converting an image of the object input through the lenses into electrical signals;

camera support means including;

a camera driver on which the camera is mounted, said camera driver rotating the camera around a first axis between first and second rotation limits and a second axis between third and fourth rotation limits, said second axis being perpendicular to the first axis; and

a rotation limit detector for detecting whether the camera reaches any of said first through fourth rotation limits and outputting a detection signal when one of said first through fourth rotation limits is reached by the camera;

a first controller for comparing a current unit image output from the camera with a previous unit image, detecting a motion vector of the object, and controlling said camera driver so that the camera moves in a direction and degree corresponding to the motion vector; and

a second controller for adjusting the zoom lens in a direction for expanding an object search region of the camera whenever the camera reaches one of said first-through fourth rotation limits, thereby allowing the camera to track the moving object, and adjusting the automatic focusing lens using a luminance component of the image received in the camera,

wherein said camera support means comprises;

a base;

said camera driver including a first motion carrier mounted on said base and connected to a first motor via a first shaft, for rotating said camera in the horizontal direction as the first motor rotates, and a second motion carrier mounted on said first motion carrier and connected to a second motor via a second shaft distinguished from said first shaft, for rotating said camera in the vertical direction as the second motor rotates; and

said rotation limit detector including said first and second motion carriers, each having a hole formed therein, a position sensor provided at each of the first and the second rotation limit positions of the first motion carrier and a position sensor provided at each of the third and fourth rotation limit positions of the second motion carrier for outputting a detection signal if the hole of one of the first and second motion carriers reaches the position of one of the sensors as the motion carriers rotate.

2. The apparatus according to claim 1, wherein said second controller continuously performs a zooming operation in the direction of expanding the object search region of the camera until the object is included in a predetermined effective region.

3. The apparatus according to claim 2, wherein said predetermined effective region is a region for determining whether the object approaches the center of a screen of the camera.

4. The apparatus according to claim 3, wherein said effective region is set at a proper configuration in advance according to a use to which the apparatus for automatically tracking the moving object is to be applied, in which the set configuration is set equal to or smaller than the camera screen.

5. The apparatus according to claim 2, wherein said second controller judges that the object is beyond the object search region of the camera when the object is not included in the predetermined effective region and the zoom lens reaches a zooming limit;

and

wherein the second controller initializes the camera when the object is judged to be beyond the object search region of the camera.

6. The apparatus according to claim 2, wherein said second controller performs a zooming operation in a direction that enlarges an appearance of the size of the object until the region ratio becomes greater than or equal to a predetermined value, said region ratio corresponding to an area occupied by the object with respect to the effective region, in order to prevent the appearance of the size of the object from being excessively reduced in size.

7. A method for automatically tracking a moving object for use in an apparatus including a camera having a zoom lens and an automatic focus lens, for converting an image of an object into electrical signals, a driver for rotating the camera in at least two directions which are orthogonal to each other, a detector for detecting limits of the rotational range in each direction of the camera and controllers for controlling the camera, the driver and the detector, the automatic object tracking method comprising the steps of:

(a) comparing sequential unit images of the object with each other, detecting a motion vector of the object, generating camera control signals corresponding to the detected motion vector, and controlling the camera to track the moving object; and

(b) performing a zooming operation in a direction for expanding an object search region of the camera until the object is positioned within a predetermined effective region whenever it is checked that the camera reaches a limit of one of the rotational ranges of the camera,

wherein said step (b) comprises;

(b1) checking whether the camera reaches a limit of the rotational range in at least one direction;

(b2) continuously performing a zooming operation in the direction of enlarging the object search region of the camera whenever the camera reaches the limit of the rotational range in at least one direction in said step (b1);

(b3) judging whether the object is included in a predetermined effective region said step (b2), continuously performing a zooming operation until the object is included in the predetermined effective region, and rotating the camera one step in the direction reverse to the previous rotational direction once the object is included in the predetermined effective region, to then stop the zooming operation; and

(b4) initializing the camera if the object it is not included in the effective region and the zoom lens reaches a zooming limit.

8. The method according to claim 7, wherein if the camera does not reach a limit of the rotational ranges with respect to all directions in the result of said step (b1) and a region ratio is smaller than a predetermined value, said region ratio corresponding to a ratio of the region occupied by the object with respect to the effective region on a camera screen, a zooming operation is continuously performed in a direction of enlarging the size of the object until the region ratio is larger than the predetermined value.

9. The method according to claim 7, wherein said step (b1) judges that the camera reaches a limit of the rotational ranges in at least one direction of the camera if at least one sensor installed at positions corresponding to the limits of the rotational ranges of the camera is activated.

10. The method according to claim 7, wherein the predetermined effective region of said step (b3) is a region set to determine whether the object is positioned in a center portion of a camera screen.