MOVING OBJECT IMAGE TRACKING APPARATUS AND METHOD

• US 20100246886A1
• Filed: 08/31/2009
• Published: 09/30/2010
• Est. Priority Date: 03/26/2009
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakamura, Hiroaki, Kuroiwa, Tadashi
• Granted Patent: US 8,098,893 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments

Abstract

An apparatus includes a first-computation unit computing first-angular-velocity-instruction values for driving first-and-second-rotation units to track a moving object, using a detected tracking error and a detected angles, when the moving object exists in a first range separate from a zenith by at least a preset distance, a second-computation unit computing second-angular-velocity-instruction values for driving the first-and-second-rotation units to track the moving object and avoid a zenith-singular point, using the detected angles, the detected tracking error and an estimated traveling direction, and a control unit controlling the first-and-second-rotation units to eliminate differences between the first-angular-velocity-instruction values and the angular velocities when the moving object exists in the first range, and controlling the first-and-second-rotation units to eliminate differences between the second-angular-velocity instruction values and the angular velocities when the moving object exists in a second range within the preset distance from the zenith.

Claims

1. A moving object image tracking apparatus comprising:

a first rotation unit configured to rotate about an azimuth axis vertically oriented and rotatably supported;

a second rotation unit configured to rotate about an elevation axis rotatably supported and horizontally oriented, the elevation axis being perpendicular to the azimuth axis, the second rotation unit being horizontally rotatable from a front position at which the second rotation unit faces a front, to a back position at which the second rotation unit faces a back, via an angular position corresponding to a zenith, the second rotation unit having a movable range of at least 180°

;

a driving unit configured to drive the first rotation unit and the second rotation unit to rotate independent of each other;

an acquisition unit supported by the second rotation unit and configured to acquire image data of a moving object by photography;

a first detection unit configured to detect, in the image data, a tracking error indicating a deviation of the moving object from a center of a field of view of the acquisition unit;

a second detection unit configured to detect angles indicating attitudes of the first rotation unit and the second rotation unit;

a third detection unit configured to detect angular velocities of the first rotation unit and the second rotation unit;

a first computation unit configured to compute first angular velocity instruction values for driving the first rotation unit and the second rotation unit to track the moving object, using the detected tracking error and the detected angles, when the moving object exists in a first range separate from the zenith by at least a preset distance;

an estimation unit configured to estimate a traveling direction of the moving object using the detected angles and the detected tracking error, when the moving object exists in a second range within the preset distance from the zenith;

a second computation unit configured to compute second angular velocity instruction values for driving the first rotation unit and the second rotation unit to track the moving object and avoid a zenith singular point, using the detected angles, the detected tracking error and the estimated traveling direction; and

a control unit configured to control the driving unit to eliminate differences between the first angular velocity instruction values and the angular velocities when the moving object exists in the first range, and to control the driving unit to eliminate differences between the second angular velocity instruction values and the angular velocities when the moving object exists in the second range.

2. The apparatus according to claim 1, wherein the estimation unit detects a position of the moving object in a zenith coordinate system, based on a positional component of an optical axis of the acquisition unit determined from the detected angles, and a positional component of the optical axis determined from the detected tracking error, and the estimation unit estimates a traveling direction of the moving object based on a difference between a currently detected position of the moving object and a position of the moving object detected a sampling interval before.

3. The apparatus according to claim 1, wherein until the moving object passes the zenith, the second computation unit controls a first angular velocity of the first rotation unit to cause a difference between an angle of the azimuth axis of the first rotation unit and the traveling direction to approach 0.

4. The apparatus according to claim 1, wherein after the moving object passes the zenith, the second computation unit controls a first angular velocity of the first rotation unit in accordance with the detected tracking error, to compensate for the detected tracking error.

5. The apparatus according to claim 1, further comprising a third computation unit configured to estimate an angular velocity of the moving object in accordance with the detected tracking error when the moving object exists in the second range,

and wherein if the second computation unit starts to track the moving object in the second range, and if the optical axis falls within a certain range of the field of view, the second computation unit controls a first angular velocity of the first rotation unit to compensate for the detected tracking error, and controls a second angular velocity of the second rotation unit to cause the second rotation unit to orient the zenith.

6. The apparatus according to claim 5, wherein when the moving object exists in the first range, the third computation unit estimates the angular velocity of the moving object based on the angles detected by the second detection unit and the angular velocities detected by the third detection unit.

7. A moving object image tracking method comprising:

preparing a first rotation unit configured to rotate about an azimuth axis vertically oriented and rotatably supported;

preparing a second rotation unit configured to rotate about an elevation axis rotatably supported and horizontally oriented, the elevation axis being perpendicular to the azimuth axis, the second rotation unit being horizontally rotatable from a front position at which the second rotation unit faces a front, to a back position at which the second rotation unit faces a back, via an angular position corresponding to a zenith, the second rotation unit having a movable range of at least 180°

;

driving the first rotation unit and the second rotation unit to rotate independent of each other;

preparing an acquisition unit supported by the second rotation unit, and acquiring image data of a moving object by photography;

detecting, in the image data, a tracking error indicating a deviation of the moving object from a center of a field of view of the acquisition unit;

detecting angles indicating attitudes of the first rotation unit and the second rotation unit;

detecting angular velocities of the first rotation unit and the second rotation unit;

computing first angular velocity instruction values for driving the first rotation unit and the second rotation unit to track the moving object, using the detected tracking error and the detected angles, when the moving object exists in a first range separate from a zenith by at least a preset distance;

estimating a traveling direction of the moving object using the detected angles and the detected tracking error, when the moving object exists in a second range within the preset distance from the zenith;

computing second angular velocity instruction values for driving the first rotation unit and the second rotation unit to track the moving object and avoid a zenith singular point, using the detected angles, the detected tracking error and the estimated traveling direction; and

controlling the first rotation unit and the second rotation unit to eliminate differences between the first angular velocity instruction values and the angular velocities when the moving object exists in the first, range, and controlling the first rotation unit and the second rotation unit to eliminate differences between the second angular velocity instruction values and the angular velocities when the moving object exists in the second range.