JPS61189474A - Tracking device for object - Google Patents

Abstract

PURPOSE:To continue tracking operation by forming a means for calculating the position of a back end of an objective picture, a means for calculating an objective speed from the positional change of the back end of the objective picture and a means for calculating a forecasting objective position during the hidden period of the object. CONSTITUTION:The presence and absence of an image picture are converted into ON and OFF signal in each scanning line, and when these signals are differentiated and the timing of the trailing edges of the signals, the back end position on each scanning line can be obtained. The back end position P of the objective picture can be obtained by averaging the back end positions of respective scanning lines. The back end position P obtained by a back end position calculating circuit 8 is sent to an objective speed calculating circuit 9 and the objective speed vi is calculated on the basis of the equations I, II. When a centroid calculating circuit 4 is disabled to execute centroid calculation, that the object is hidden on the back of a shielding substance is decided and a changeover switch 11 is controlled so as to be turned to the (b) side. Thus, tracking operation can be continued without manual operation every time that the object is hidden.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a target tracking device that automatically tracks a moving target using a sensor such as a television camera.

[Conventional technology]

FIG. 4 is a block diagram of a commonly used optical target tracking device (TV tracker). In the figure, (1
) is a television camera, (2) is a digitization circuit that quantizes the video signal captured by the television camera (1) and converts it into a digital signal, and (3) is this digitized image signal. Image memo 17 for temporarily storing the image as an image, <4) is a center of gravity calculation circuit for calculating the center of gravity position of this image, and (5) is a center of gravity calculation circuit for calculating the center of gravity position of this image. This is a control circuit for outputting a control signal to the servo mechanism (6).

A conventional target tracking device is configured as described above.

For example, a certain target can be captured by a television camera (1), and an image of the target can be obtained on the image memory (3).

When automatic tracking is instructed, the center of gravity calculation circuit (1) uses the center of gravity position of the image on the image memo (January 3) as the target position (7).
4) is calculated, and thereby the control circuit (5) adjusts the direction so that the pointing center of the television camera (1) and the target position coincide.
Calculates and outputs a control signal to the servo mechanism (6).

[Problem that the invention seeks to solve]

In a target tracking device such as the one described above, when the target is temporarily hidden behind an object and cannot be seen.

Obtain the speed and direction of the target from the previous tracking data, estimate the target's position until the target is visible again,
Need to keep tracking.

However, the speed of the target just before it disappears behind an object can be determined from the change in the center of gravity of the target image captured by a television camera.

As is clear from Fig. 5, since the target H is hidden behind the obstruction (13), the calculated center of gravity position shifts from the true center of gravity position, and the apparent speed of the target is significantly reduced. Even if you predict the target's motion at this speed and continue tracking, it will not work again.

When the target emerges from cover, the target cannot be seen within the tracking field of view. For example, in FIG. 5, the true center of gravity position x of the target +11 at time 2 N matches the center of gravity position calculated by the center of gravity calculating circuit.

At time N+1, the center of gravity position is calculated only from the shaded area α2 of the image of the target α3, and it deviates from the true center of gravity X.

This invention was made in order to solve these problems, and the purpose of this invention is to obtain the true movement speed of the target just before it hides behind an object, and calculate the movement of the target while it is hidden behind an object. The object of the present invention is to provide a target tracking device that can correctly predict the following and continue the tracking operation.

[Means for solving problems]

The target tracking device according to the present invention includes means for calculating the position of the rear edge of the target image instead of the position of the center of gravity of the target image, and means for calculating the position of the rear edge of the target image based on the position change of the rear edge of the target image in order to calculate the true moving speed of the target. Means for calculating the velocity and means for calculating the predicted target position while the target is hidden behind an obstruction are provided.

[Operation] In this invention, the moving speed of the target is calculated not from the change in the position of the center of gravity of the target image, but from the change in the position of the rear end,
Since the position of the target is predicted when it is no longer visible, automatic tracking can continue if the target appears again.

〔Example〕

FIG. 1 is an overall configuration diagram showing an embodiment of a target tracking device according to the present invention. The embodiment of the present invention shown in FIG. 1 is obtained by adding a rear end position calculation circuit (8), a target speed calculation circuit (9), a predicted target position calculation circuit 01, and a changeover switch I to the device shown in FIG. be.

FIG. 2 is an explanatory diagram of the calculation algorithm of the rear end position calculation circuit (8). In the figure (a) is image memory (3)
In the content of the image data above, the diagonally shaded portion α3 is the target. For each 1.2.5...N scanning line in the figure, presence or absence of the image is changed to an on or off signal.

By differentiating these and detecting the falling timing, we get
Trailing end position P1*P2+...PN on each scanning line
but.

Obtained as illustrated in (b). By averaging these, the rear end position P of the target image can be obtained.

However, in the two examples, the target is moving to the left of the roundworm.

Next, the operation of the above embodiment will be explained.

In FIG. 1, the rear end position P obtained by the rear end position calculation circuit (8) is sent to the target speed calculation circuit (9).

Target speed v1 is calculated by the following equation.

x1=@x1-1+(f-K)・P ・・・−・・
...(1)v, -J -vx-t + (1-J
) −(Xi−Xl−j ), + song (2) However,
K and J are constants set according to the dynamic characteristics of the target, and xl is the current target position #XL-1 is the value of the target position in the previous calculation cycle.

vl-1 is the value of the target speed in the previous calculation cycle.

The predicted target position calculation circuit a1 calculates the target position Xp! p =
! p + T ” 'Vp ”
"""' Calculate as in (3). However, T is the calculation period.

In Figure 1, the selector switch αυ is tilted to side a,
When the target image cannot be obtained, that is, when the center of gravity calculation circuit (4) is unable to calculate the center of gravity, it is determined that the target is hidden behind a shielding object, and control is performed so that the target falls to side b.

In the predicted target position calculation circuit α1, the changeover switch αυ is
If it is lying on side a, before calculating equation (3).

zp=gz1, yp=y1, and substitute xl for Xp and vl for Vp each time,
These substitutions are not made when the changeover switch aυ is in b.Therefore, when the changeover switch I is in b, the last speed and position when the changeover switch αD was in a are held, and from now on, The target position is predicted and the control circuit (5
).

FIG. 3 shows the calculation flow of the predicted target position calculation circuit.

By operating the changeover switch t1υ, the center of gravity position of the input image of the actual target is tracked while the target is visible, and the target position predicted within this device is tracked when the target is behind an obstruction. As you do.

A control circuit (5) drives a servomechanism (6).

In addition, the center of gravity calculation circuit (4), rear end position calculation circuit (8), target speed calculation circuit (9), predicted target position calculation circuit, changeover switch U, etc. in the above embodiment are 7.-
It may be realized by Dounia logic or by a microcomputer and its program.

〔Effect of the invention〕

As described above, according to the present invention, even if the target is temporarily hidden behind an object, automatic tracking is continued using the previous data, so it is not necessary to return to manual operation every time the target is out of sight. This greatly increases the usefulness of automatic tracking devices.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of a target tracking device according to the present invention, and FIG. 2 is a rear end position calculation circuit (8
), Fig. 3 is the calculation flow of the predicted target position calculation circuit (9), Fig. 4 is an overall configuration diagram of a conventional target tracking device, and Fig. 5 is a diagram showing the problems encountered in the conventional target tracking device. It is an explanatory diagram of the operation. In the figure, (1) is a television camera, (2) is a digitizing circuit, (3) is an image memory, (4) is a center of gravity calculation circuit, (5) is a control circuit, (6) is a servo mechanism, (7) is
is a target position signal, (8) is a rear end position calculation circuit, (9) is a target speed calculation circuit, α[ is a predicted target position calculation circuit, and α force is a changeover switch. Note that the same reference numerals in the two figures indicate the same or corresponding parts.

Claims (1)

[Claims] An image memory that temporarily stores the image of the target obtained from the sensor as image data; a center of gravity position calculation circuit that calculates the center of gravity position of the image data on the image memory based on the output of this image memory; A trailing edge position calculation circuit that detects the moving direction of the target and calculates its trailing edge position based on the change in the gravity center position calculated by the gravity center position calculation circuit, and A target speed calculation circuit and a predicted target position calculation circuit calculate the speed of the target and the future position of the target from the changes, respectively, and the target position information calculated by the predicted target position calculation circuit or the center of gravity position calculated by the center of gravity position calculation circuit. A target tracking device comprising: a changeover switch for introducing any of the target position information into a control means for controlling the pointing direction of the sensor.