JPS5923515B2 - Automatic target tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic target tracking device that compares images of an imaging target area obtained at different times using an imaging device, and controls the imaging direction of the imaging device based on the comparison output.

In such an automatic tracking device, a target image signal is extracted by detecting the level difference in the image signal due to the contrast difference between a specific target image and a background image in the image, and the deviation of this signal on the imaging screen is detected. The so-called point tracker method is used, which generates an error signal and sends this signal as a servo signal to the camera platform supporting the imaging device to track the target so that the target image is always visible on the imaging screen. There is.

However, in this point tracker method, only the outer peripheral part of the target or a part within the target where a certain contrast can be obtained is tracked, so as the target moves, the contrast with the background decreases. Parts of the target object are often obstructed by other obstacles, and automatic tracking becomes impossible in many cases. In such a case, it is necessary to add a memory circuit or the like to the tracking device to temporarily secure an image signal of the area where the target was present, and then re-capture a predetermined contrast portion when the target appears again.

However, when a tracking device is mounted on an aircraft, for example, the relative positional relationship with the target changes at high speed, so partial tracking deviations are large and it is difficult to re-acquire the target. . In addition, in order to eliminate these drawbacks,
It is necessary to add an expensive and complicated device using a computer, etc., and in order to re-acquire and re-track the target in a short time; Furthermore, we focused on a very partial area within the imaging target area as described above, and set the contrast of that partial area to ``0-''.
Until now, no effective remedy has been considered for damage caused when the target point is used for tracking, that is, when the target point is lost.

The present invention has been made in view of the above circumstances, and includes a target detection system using one type of point tracker and a target detection system using one type of area tracker. 6. When the target cannot be detected using this method, it is automatically detected and automatically switched to target detection using one area tracker method, and automatic tracking control of the target is performed using the target detection output using one of the above methods. The present invention provides an automatic target tracking device that can ensure target tracking.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In Figure 1. Reference numeral 11 denotes a television image pickup device using a television image pickup tube or a television scanning type image pickup element array.

The television video signal obtained by imaging the imaging target area by this imaging device 11 is transmitted to a point tracker one-type detection device 12 and an area tracker one-type detection device 1.
I am guided by 3. Each servo control error signal output obtained by each of the detection devices 12 and 13 is led to an automatic switching device 14. This switching device 14 selects and derives the servo control output of the point tracker one-type detection device 12 while the detection operation signal obtained during the target detection operation is being guided. When the switching device 14 can no longer obtain a detection operation signal from the 6-point tracker one-type detection device 12, it automatically detects this and sends a switching command signal to the area tracker one-type detection device 13.
By this command signal, the area tracker one-type detection device 13
The system automatically performs five switching operations to select and derive the servo control error signal output from the servo controller. The servo control error signal derived from the switching device 14 in this manner is guided to the drive device 15, which drives the pan head 16 so that the error signal input becomes zero, thereby changing the imaging direction of the imaging device 11. Control.

Note that the imaging device 11 is not limited to a normal television imaging device, but may also be a device that uses infrared photography or laser beams. Next, the principle of the point tracker one-type detection device 12 will be explained.

Figure 2a shows an example of a screen obtained by guiding the imaging signal output of the imaging device 11 to a television monitor.It is assumed that there is a target image in the center of the screen, for example6, and that it is brighter than the background image. .

Therefore, the video signal during the horizontal scanning period during which the target image is scanned becomes as shown in FIG. 2b. When such a video signal is guided to the point tracker one-type detection device 12,
Here, a target image pulse signal is detected based on the level difference of the video signal (that is, the contrast difference between the target image and the background image).
A change in the position of this target image signal on the screen is detected and output as an error signal. Note that the target multi-sensor signal output is guided to the automatic switching device 14 as a detection operation signal indicating that the six target detection operation is in progress. Next, an example of the area tracker one-type detection device 13 will be explained in detail.

First, in the screen shown in FIG. 3, portions A and B surrounded by solid lines indicate the area of the selected reference scene position on the screen.

Video signal (video signal) of parts A and B surrounded by the solid line
can be easily derived using analog gate circuits of known technology. And area tracker one type detection device 1
3, the video signal of the part A surrounded by a solid line is taken out as a vertical signal, and the video signal of part B, also surrounded by a solid line, is taken out as a horizontal signal. This method detects the phase change of the video signal when the video (image) moves. Note that the method of extracting each of the vertical and horizontal signals and detecting the phase change in each of the above two directions can be realized in principle with the same mechanism in either direction, so the explanation will be given for one direction and the other. is omitted.

In FIG. 4, the image of the imaging target area obtained by the imaging device (FIG. 1 11), that is, the video signal, is supplied to an analog gate circuit 51 (6) where it is displayed as a solid line on the monitor screen as shown in FIG. 3. A horizontal video signal in the area of the enclosed portion B is obtained.

Therefore, the output of the six analog gate circuit 51 is given in a waveform as shown by the solid line a in FIG. 5a.

The output of the analog gate circuit 51 is supplied to an analog-to-digital converter 53 that sequentially digitizes the analog image pattern. The analog-to-digital converter 53 is a smoothing circuit 54
, a first delay circuit 55, and a comparator 56.

The video signal output from the analog gate circuit 51 is divided into six branches, one of which is supplied to a smoothing circuit 54. The smoothing circuit 54 is composed of a low-frequency wave filter, and derives a smoothed waveform as shown by the dotted line A in FIG.
supply to. On the other hand, the other video signal branched from the analog gate circuit 51 is supplied to the delay circuit 55, and after being compensated for the delay time so that the time delay matches the signal on the smoothing circuit 54 path, the signal is sent to the comparator 56. supplied to In this comparator 56. 5A from the smoothing circuit 54 and the signal indicated by the dotted line A in FIG. 5A from the delay circuit 55.
The amplitude level is compared with the signal shown in solid line A, and only when the output amplitude from the 6 delay circuit 55 is large, the level is set to "1".
In other cases, a binary pulse code as shown in FIG. 5b at level "0" is derived. The binary pulse code output thus obtained from the analog-to-digital converter 53 is supplied to an electronic switch 57.

The electronic switch 57 selectively transfers the output signal of the analog-to-digital converter 53 to the first storage circuit 58 and the second storage circuit 5 according to the frame image obtained by the imaging device 11.
It is configured so that the supply can be switched to 9.

Both the first and second storage circuits 58 and 59 only need to have a capacity capable of storing a binary pulse code corresponding to one frame image.

Contents to be compared and contrasted with each other are stored in the first storage circuit 58 and the second storage circuit 59, respectively.

In this embodiment, the content of the first reference image capture screen from the six imaging devices is stored in the first storage circuit 58, and the content of the images to be compared and contrasted that are sequentially obtained from the same imaging device. are replaced and stored in the second storage circuit 59 one after another. Therefore, the digital signal of the first frame image obtained by the imaging device is stored in the first storage circuit 58, and the digital signal of the second, third, and so on frame images is stored in the second storage circuit 58. 59 and stored so as to be sequentially replaced. The first and second storage circuits 58 and 59 as described above are constructed of shift registers, magnetic drums, or the like.

Further, a second delay circuit 60 is added to the second memory circuit 59, and the structure is configured such that the delay time can be arbitrarily set via the second delay circuit 60 and the data can be read out repeatedly. 1. Therefore, the signal 6 read out from the first storage circuit 58 and the digital signal stored in the second storage circuit 59 are sequentially shifted by the second delay circuit 60 and the readout signals are sequentially transferred to the detector. 61.

The detector 61 is composed of an adder 62 and an error detector 63. The adder 62 introduces digital signals corresponding to one frame image from the first storage circuit 58 and the second delay circuit 60, respectively, and performs an AND operation on the two digital signals. A cumulative addition signal of matching signals for each frame image is derived.

The operation of this adder 62 will be explained in detail with reference to FIG.

FIG. 6a shows a digital signal stored in the first storage circuit 58, and FIG. 6b shows a digital signal stored in the second storage circuit 59.

In FIG. 6b, symbol B.

indicates a signal stored in the second storage circuit 59, and the symbols B1, b2, . . . , B4 below are respectively B. (Delay time T.=0) as a reference, the second delay circuit 60 delays each time Tl, t2, . . . T4.
Therefore, the digital signals indicated by these symbols Bl, b2...B4 are digital signals B. are respectively displaced and compared with the digital signals shown in FIG. 6a. In the adder 62, the signal shown in FIG. 6a stored in the first storage circuit 58 and the signal read out from the second storage circuit 59 and sequentially shifted by time delay are made to correspond. A digital match (and) is made.

As a result, as shown in FIG. 6c, a coincidence signal C whose pulse width changes according to each displacement is obtained. , Cl...C4 can be obtained. Next, the adder 62 adds these matching signals, thereby increasing the read delay times Tl, t2, . . . in the second storage circuit 59, as shown in FIG.
- Amplitude information corresponding to T4 can be obtained.

Each amplitude level of this amplitude information (CI, Cr...C4●
6 corresponds to the deviation between the two digital signals that are read out and compared, so it is assumed that they match when the amplitude level is the maximum (Cm). Let the delay time at this time be Tm. Note that in this embodiment, the second delay circuit 60 is
Although the delay circuit is connected to the first memory circuit 59, the delay circuit may be provided on the first memory circuit 58 side as long as the signal input to the adder 62 is relatively displaced.

In short, the second delay circuit 60 determines how much difference there is between the information stored in the first storage circuit 58 and the information stored in the second storage circuit 59. In other words, in images captured by the same imaging device, It serves as a so-called variable phase shifter for relatively comparing the degree of deviation between the first frame image and the second frame image. In FIG. 7, the time Tnl at which the maximum output amplitude Cm is obtained is the reference delay time T.

Compare with. Although the direction is shown as having a large delay (to the right), there are of course cases where the delay is actually in the opposite direction. However, since the purpose is to obtain a relative comparison with the signal shown in FIG. 6a, the reference time T is used. All you have to do is shift it to the left in advance. Now, the output of the adder 62 is supplied to an error detector 63.

The error detector 63 uses the signal stored in the second storage circuit 59 and receives, for example, substantially no delay compensation in the second delay circuit 60 as a reference time T.

signal and set. The error base detector 63 detects the reference time T of the signal that is not subjected to this delay compensation. The time difference signal (TrI]-T until receiving the time Trn at which the maximum amplitude information is obtained from
O) is detected. This time difference signal (t[n-TO) corresponds to the deviation of the image patterns stored in the first and second storage circuits 58 and 59, that is, the displacement.

Therefore, if there is no phase difference between the stored digital signals and they match, Tnl=TO. On the other hand, a vertical synchronization signal for the imaging operation is supplied from the imaging device 6 (FIG. 11) to the control circuit 64.

This control circuit 64 includes the automatic switching circuit (FIG. 14).
), when an output command signal is derived, a control signal for controlling the switching operation of the electronic switch 57 is derived at the timing of the vertical synchronization signal. The electronic switch 57 normally sends the image of the reference area of the tracking target to the first storage circuit 58 and sequentially stores the signals of new frames. By outputting a control signal at that time, the subsequent second, third, etc. frame images are switched and supplied to the second storage circuit 59. Further, a switch switching control signal is also supplied from the error detector 63 of the detector 61 to the electronic switch 57. The switch switching control signal from the error detector 63 is supplied when a normal tracking error detection signal cannot be obtained from the error detector 63. for example. When the center of the target area is accurately captured, the six imaging patterns are often simply enlarged or reduced when the distance becomes closer or farther away. Therefore, the pulsed pattern signal is changed from a to b or b to a in FIG.
By only changing as shown in FIG. 8, the output of the adder 62 will only have flat support as shown in FIG. 8c, and will not become a tracking error signal with a so-called phase difference. Therefore, in such a case, the electronic switch 57 is controlled by the output of the error detector 63, and the output of the analog-to-digital converter 53 is supplied to the first storage circuit 58 to update the reference signal. The six-area tracker one-type detection device 13 described above converts an image pattern into a digital signal, and sequentially compares the first imaging pattern with the second and third imaging patterns to detect a phase difference. Since the comparison result is used to control the imaging direction of the imaging device, the probability of securing an imaging area including the target image is sufficiently large compared to the point tracker one-type detection device 12, and the target tracking function is significantly improved. improves.

Note that in the above embodiments, the configuration in which the direction control of the imaging device is controlled only in the horizontal direction has been described. Tracking in all directions can be easily realized by adding a vertical control system to the configuration of the analog gate circuit 51 and also providing a signal processing system after 6.

That is, an example of the area tracker one-type detection device described above is 6.
An imaging device that sequentially obtains images of a region to be imaged, an analog-to-digital converter that sequentially digitizes analog image patterns obtained by the imaging device, and a first image pattern obtained by the converter. a first memory circuit that stores 6; and a second memory circuit that stores a second image pattern obtained at a different time from the first image pattern stored in the first memory circuit; Detection for moving the second image pattern stored in the second storage circuit so that the positions of the first image pattern are relatively displaced and deriving the amount of displacement until the two image patterns match. Equipped with utensils.

Next, an example of the automatic switching device 14 will be explained in detail.

In FIG. 9, the synchronization signal input terminal 71 is connected to an imaging device (
A horizontal synchronizing signal is introduced from the six target image pulse input terminals 72 (FIG. 11), and a target image pulse signal is introduced from the point tracker one-type detection device (FIG. 12).

The target image pulse signal input and the horizontal synchronization signal input are led to an AND circuit 73. The AND output of the AND circuit 73 is guided to the reset input terminal R of the flip-flop circuit 74. Further, the horizontal synchronization signal is input to a first monostable multi-circuit 75 that responds to the falling edge of the input pulse, and a second monostable multi-circuit 76 that responds to the rising edge of the input pulse.
guided by. The output pulse of the second monostable multicircuit 76 is connected to the set input terminal S of the flip-flop circuit 74.
guided by. The Q of this flip-flop circuit 74 is
The output pulse of the output terminal and the output pulse of the first monostable multi-circuit 75 are guided to an AND circuit 77. Therefore, in the automatic switching device, the switching command signal is not generated or generated at the output of the AND circuit 77 depending on whether or not the target image pulse signal is input.

This operating waveform is shown in Figures 10 and 11.
Figure 0 shows the case where there is a target image pulse signal input. 6 Figure 11 shows the case where there is no target image pulse signal input. In each case, a is the horizontal synchronizing signal input, b is the level 6c of the target image pulse signal input terminal 72, and The output of the circuit 73, d is the output pulse of the flip-flop circuit 74, and e is the output pulse 6f of the first monostable multi-circuit 75.
6 output pulses. g is the output of the AND circuit 77. The output of the AND circuit 77 is then led to a switch circuit 78, and when the switching command signal 6 is not generated at the output of the AND circuit 77, the error signal output of the point tracker one-type detection device (Fig. 1 12) is led to the switch circuit 78. When the switching command signal is generated at the output of the AND circuit TT, the error signal output of the area tracker one-type detection device (FIG. 1, 13) is selected and derived by the switch circuit T8. .

Therefore, according to the automatic target tracking device as described above,
It is equipped with a point tracker one-type detection device and an area tracker one-type detection device, and when the target cannot be detected by the point tracker one-type detection device, the output of this device is used to track the target. When this device is unable to detect a target, it is automatically detected and automatically switched to use the output of the area tracker one-type detection device, so that target detection using the point tracker one-type detection device is no longer possible. It is also possible to capture the space including the date mark using the area tracker method. If the target becomes prone again and can be detected using the point tracker method, the target can be reacquired. Target tracking can be ensured.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the automatic target tracking device according to the present invention, and FIG. 2 is a diagram showing the principle of the point tracker one-type detection device of FIG. 1.
3 to 8 show an example of the area tracker one-type detection device shown in FIG. 1, and FIG. 3 is a pattern diagram showing the imaging target area. Figure 4 is a block diagram of the device, and Figure 5 is a signal waveform diagram explaining the operation of the analog-to-digital converter shown in Figure 4. 6 to 8 are signal waveform diagrams shown to explain the operation of the detector shown in FIG. 4, FIG. 9 is a block diagram showing an example of the automatic switching device shown in FIG. 1, and FIGS.
FIG. 1 is a signal waveform diagram shown to explain the operation of FIG. 9. 11: Television camera imaging device, 12: Point tracker one-type detection device, 13: Area tracker one-type detection device, 14: Automatic switching device. 15: Drive device.

Claims (1)

[Claims] 1 An imaging device that performs television scanning, and an image signal output of this imaging device is guided, and a target image signal corresponding to a specific target in the imaging screen of the imaging device is generated by a level difference portion in the image signal output. a point tracker type detection device that detects and outputs an error signal according to the temporal deviation of the target image signal between each imaging frame; and a point tracker type detection device that outputs an error signal according to the temporal deviation of the target image signal between each imaging frame; an area tracker type detection device that extracts a scene image signal corresponding to a scene and outputs an error signal according to a temporal deviation of the scene image signal between each imaging frame; and a target image signal in the point tracker type detection device. an automatic switching device for selectively deriving the error signal output of the point tracker type detection device or the error signal output of the area tracker type detection device depending on the presence or absence of a detection output; and the imaging device controlled by the error signal derived from this device. 1. An automatic target tracking device comprising: a drive device that tracks the imaging direction of the image in the direction of the target.