JP3519648B2 - Automatic tracking device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking device in a multifunction radar system having an electronic scanning antenna, for example.

[0002]

2. Description of the Related Art Generally, when a certain air space is searched by a radar and an automatic target tracking of a track-wil scan (TWS) system is performed, an unnecessary video signal due to the sea surface or clouds or a disturbing wave intentionally radiated is used. In order to prevent erroneous tracking, a method has been adopted in which a correlation gate is generated around an already-discovered target and unnecessary video signals are removed. An example thereof is shown in FIG.

That is, the received video signal obtained by the radar device 10 is input to the quantizer 11 and is "1" at a certain threshold value for each processing unit in the distance direction called a range bin.
(= Target), “0” (= no target). This quantized signal is sent to the AND gate 12 and ANDed with a correlation gate (“1” = around the target predicted position, “0” = other) generated by a correlation gate generator 18 described later. This logical product output is the run length determiner 13
The run length is judged by the sliding window.

The discriminated video signal is input to the correlator 14. The correlator 14 correlates the input video signal with the previous predicted position calculated by the next position predictor 16 based on the beam angle and distance information obtained by the radar device 10. The correlation result is smooth. In the device 15, smoothing processing by various algorithms is performed as described later, and thereby the observation error is removed. Then, the smoothed position data is sent to a display device or the like, appropriately displayed, and displayed.

In the smoothing process, for example, Xp is a predicted position,
When Xx is the measured position and α is a coefficient, the equation Xp + α (Xx−Xp) holds, and T is the search cycle, and β is a coefficient and is calculated based on the equation Xp + β / T (Xx−Xp). .

The smoothed position processed by the smoother 15 is
Next time, it is sent to the position predictor 16, where the predicted position for the next search is obtained from the position and speed, and stored in the position memory 17. At this time, the position prediction is obtained using the current search time. The position data stored in the position memory 17 is sent to the correlation gate generator 18.

The correlation gate generator 18 generates a correlation gate corresponding to the position data read from the position memory 17 based on the beam angle and distance information from the radar device 10. The correlation gate is
It is sent to the AND gate 12 described above.

The above operation will be described with reference to FIG. 4 in terms of movement in space.

The next predicted position 23 is obtained from the smoothed position and speed closest to the predicted position 20 and updated by the observation position 22 in the correlation gate 21 and the time until the next search. The correlation gate 24 is set to the next prediction device 23 and waits until the next search is completed. At the time of the next observation, the next predicted position is obtained in the same manner as above using the observed position 25 that is closest to the predicted position 23 and is inside the correlation gate 24. Or later,
By repeating the same operation, the target can be continuously tracked.

However, in the above-mentioned conventional method, although no particular problem occurs in the case of a radar apparatus having a fixed search time such as mechanical scanning, it has the following drawbacks.

For example, in a multi-functional radar device capable of arbitrarily changing the search time by electronic scanning, the function as a search radar and the function as a tracking radar are processed in a time division manner. The radar device 10 has a characteristic that the search time greatly changes due to an increase or decrease in the number of tracking targets or a change in the tracking sample rate due to a change in target motion.

FIG. 5 shows the state of the tracking processing of the conventional track-and-wheel scan system when the search time changes.

That is, in the conventional tracking processing method, as is apparent from FIG. 5, when the search time changes (when the search time becomes long in the figure), the next predicted position 31 calculated from the current observation position 30 is obtained. Next time the observation position 32 will be displaced,
There is a problem that the quality of the track for target tracking deteriorates.

Further, according to this, the next predicted position 3
If the deviation between 1 and the next observation position 32 is large, there is a risk of mistracking due to deviation from the correlation gate.

[0015]

As described above, the conventional automatic tracking device calculates the next target position at the time of target observation and sets the correlation gate. There is a problem in that the calculated next predicted position and the next observed position are displaced from each other, and the track quality of the target tracking is deteriorated. Also, if this deviation is large, there is a risk that the deviation from the correlation gate may occur and false tracking may occur.

The present invention has been made to solve the above problems, and provides an automatic tracking device capable of reliably preventing a deviation between a next predicted position and a next observed position due to a change in search time. The purpose is to

[0017]

The present invention is based on a quantizer for quantizing a received video signal from a radar device for each processing unit in the distance direction, and a beam angle and distance information obtained by the radar device. A correlation gate generator that generates a correlation gate centered on a predicted position, and a gate circuit that passes only a video signal in the correlation gate generated by the correlation gate generator among the video signals quantized by the quantizer And a correlator that correlates the gate circuit output with the predicted position based on the beam angle and distance information obtained by the radar device, and a smoother that smoothes the correlation result obtained by this correlator and observes the target position. And a clock generation means for generating a clock signal having a cycle shorter than the search time of the radar device, and the clock generation for the target position obtained by the smoother. Position change amount calculating means for obtaining a position change amount in a clock signal cycle generated by a stage, and the position change amount calculated by the position change amount calculating means in the clock signal cycle generated by the clock generating means The automatic tracking device is configured to include a predicted position generation / update unit that cumulatively adds to the observation position obtained by the vessel and generates / updates the next predicted position.

According to the above configuration, the received video signal is quantized for each processing unit in the distance direction, only the video signal in the correlation gate centered on the predicted position is passed, and the predicted position is determined based on the beam angle and the distance information. Then, after smoothing, the target position is observed after smoothing.

At the same time, a clock signal having a shorter cycle than the search time of the radar device is generated, and based on this clock signal, the position change amount for the smoothed target position is obtained and the position change amount is calculated. The next predicted position is generated and updated at the clock signal cycle by cumulatively adding to the observed position obtained by the smoother. This allows
The next predicted position and the correlation gate are always updated to the latest position independently of the search time of the radar device, so that the next predicted position caused by the change in the search time is not affected by the change in the search time. Therefore, it is possible to prevent the deviation of the observation position at the next time, and it is possible to perform stable automatic tracking of the target by the track-and-wheel scan method even with the radar device in which the search time changes.

Further, the present invention is a clock generating means,
The clock signal period is set shorter than the search time, and the search time is set to an integer multiple.

According to the above configuration, since the position data is stored based on the time clock whose search time is an integral multiple, the subsequent arithmetic repair can be simplified.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An automatic tracking device according to an embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 shows the configuration of an automatic tracking device according to an embodiment of the present invention. A received video signal obtained by a radar device 10 is input to a quantizer 11. This quantizer 11 has a threshold value of “1” (= target) for each processing unit in the distance direction called a range bin,
Quantize to "0" (no target). Here, the quantized video signal is sent to the AND gate 12.

The AND gate 12 inputs a correlation gate and a quantized video signal from a correlation gate generator 18 which will be described later, and performs a logical product operation in Boolean algebra,
Extract the video signal in the correlation gate. This logical product output is sent to the run length determiner 13.

The run length judging device 13 judges the extent of spread of the input video signal by using, for example, a sliding window, and removes unnecessary signal components such as clutter. Here, the video signal subjected to the determination processing is the correlator 14
Sent to.

This correlator 14 correlates the next predicted position with the observed video signal based on the beam angle and distance information obtained by the radar device 10, and finds the position of the observed video signal with the highest correlation, for example, in polar coordinate format. Detect with. Here, the detected position data is sent to the smoother 15.

This smoothing device 15 has
As described above, for example, the observation error is removed by performing the smoothing process using an algorithm such as an α-β predictor filter. And this smoothed position data is
While being sent to the position memory 17 via the selector 19,
It is sent to the speed calculator 1A which constitutes the position change amount calculating means.

The speed calculator 1A calculates a position change per time clock (hereinafter referred to as speed data) generated by the time clock generator 1C from the observation position smoothed as described above. Then, this speed data is stored in the speed memory 1B, read at the time clock cycle, and sent to the cumulative adder 1D.

The selector 19 selects the output on the smoother 15 side when the smoothed position is updated, and selects the output from the cumulative adder 1D otherwise, and selects the position memory. Derived to 17. The position memory 17 stores the position data from the selector 19 for each time clock generated by the time clock generator 1C. Then, the stored position data is sequentially read and sent to the cumulative adder 1D.

The cumulative adder 1D cumulatively adds the speed data (position change amount) read at the time clock cycle to the smoothed position data. Then, the addition result is derived as the next predicted position to the correlator 14, the selector 19 and the correlation gate generator 18, respectively.

The time clock generator 1C generates a clock signal that periodically changes to "1" or "0" at fixed time intervals, and defines the storage timing of the position storage unit 17. As the clock signal cycle, the radar device 1
It is set sufficiently shorter than the accuracy (search time) required for 0 tracking. Then, the clock signal period is set sufficiently shorter than the search time of the radar device 10 and the search time of the radar device 10 is set to an integral multiple, whereby the arithmetic processing can be simplified.

The correlation gate generator 18 uses "1" as a correlation gate when the beam angle and the distance from the radar device 10 are around the target based on the predicted position from the cumulative adder 1D, for example, in polar coordinates. AND gate 12
, And otherwise sends “0” to the AND gate 12.

The size of the correlation gate may be controlled by the difference between the predicted position obtained by the smoother 15 and the observed position.

In the above-mentioned configuration, the AND gate 12, the run length judging device 13, the correlator 14, the smoothing device 15, the selector 19, the speed calculator 1A, the cumulative adder 1D, and the correlation gate generator 18 are the computers or the like. It can also be expressed in software. Further, if a plurality of the above-mentioned configurations are configured by hardware and software in parallel, it is possible to support a plurality of targets.

That is, in the automatic tracking device having the above-mentioned structure, the quantizer 11 sets the received video signal from the radar device 10 to "1" (= target), "0" (with a target) for each range bin. = No target), and ANDed with the correlation gate ("1" = around the predicted position, "0" = other) by the AND gate 12. And
This logical product result is input to the correlator 14 through the run length determiner 13 such as a sliding window, the correlation with the previous predicted position is obtained, and the smoothing device 15 removes the observation error by various algorithms.

Here, the obtained smoothed position data is stored in the position memory 17 via the selector 19, and at the same time, the speed calculator 1A calculates the speed data which is the position change per time clock and stores the speed. Store in device 1B. And
When the storage is completed, the selection of the selector 19 is changed to the accumulator 1
Switch to the D output side.

After this, until the next observation is completed, it is stored in the speed memory 1B at the next predicted position by the cumulative adder 1D according to the clock cycle generated by the time clock generator 1C (sufficiently shorter than the search time). The position change amount is cumulatively added, and the next predicted position is updated every time clock.
A correlation gate generator 18 generates a correlation gate centering on the next predicted position. After that, tracking is automatically performed by sequentially repeating this closed loop.

The above processing operation will be described with reference to the spatial movement shown in FIG.

First, the observation position 22 closest to the predicted position 20 and within the correlation gate 21 is smoothed as described above to obtain the smoothed position and velocity. After that, predicted position 2
3. While updating the correlation gate 21 according to the cycle of the time clock, wait until the next search is completed.

That is, even if the search time changes during this period and the next observation position changes from 26 to 27, the predicted position 23 and the correlation gate 21 are updated in accordance with the cycle of the time clock from the time clock generator 1C. To be done. Therefore, as shown in FIG. 5 described above, a deviation occurs between the next predicted position 31 calculated from the current observation position 30 and the next observation position 32 to deteriorate the track quality of the target tracking, or the deviation becomes large, and the correlation gate There is no chance that it will be mistracked.

Then, at the time of the next observation, the smoothed position and velocity are obtained in the same manner as above using the observed position 27 that is closest to the predicted position 23 and is inside the correlation gate 24. After that, the target can be continuously tracked by repeating the same operation.

As described above, the automatic tracking device is provided with the time clock generator 1C for generating the time clock at a cycle shorter than the search time of the radar device 10, and the next predicted position and the correlation gate are set to the search time of the radar device 10. And is configured to always update to the latest position independently.

According to this, the next predicted position can be updated without being affected by the change in the search time, the deviation between the next predicted position and the next observed position due to the change in the search time can be prevented, and the search time can be prevented. Even if the radar device 10 changes in position, it is possible to perform stable automatic target tracking of the track-and-wheel scan system.

In the above embodiment, the time clock generator 1C is configured to generate the time clock at a cycle sufficiently shorter than the search time, but the present invention is not limited to this. Time clock generator 1
The generation cycle of the time clock generated by C may be selectively variably set in a cycle shorter than the search time of the radar device 10. Also in this case, the clock signal period is, for example, sufficiently shorter than the search time of the radar device 10,
In addition, the search time of the radar device 10 may be set to a cycle that is an integral multiple.

According to this, the precision of the automatic target tracking can be further promoted, and a more effective effect can be expected.

Therefore, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0047]

As described above, according to the present invention,
It is possible to provide an automatic tracking device capable of reliably preventing a deviation between the next predicted position and the next observed position due to a change in the search time.

[Brief description of drawings]

FIG. 1 is a block circuit diagram shown for explaining a configuration of an automatic tracking device according to the present invention.

FIG. 2 is a diagram showing a spatial movement for explaining the signal processing operation of FIG.

FIG. 3 is a block circuit diagram showing a configuration of a conventional automatic tracking device.

FIG. 4 is a diagram showing a movement in space for explaining a processing operation in the conventional configuration of FIG.

FIG. 5 is a diagram showing a state of a tracking process of a conventional track-and-wire scan system when the search time is changed in the conventional configuration of FIG.

[Explanation of symbols]

10 ... Radar device. 11 ... Quantizer. 12 ... AND gate. 13 ... Run length judging device. 14 ... Correlator. 15 ... Smoother. 16 ... Next position predictor. 17 ... Position memory. 18 ... Correlation gate generator. 19 ... Selector. 1A ... Speed calculator. 1B ... speed memory. 1C ... Time clock generator. 1D ... Cumulative adder. 20, 23, 30, 31 ... Predicted position. 21, 24 ... Correlation gate. 22, 25, 26, 27, 32 ... Observation position.

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Claims (4)

(57) [Claims] 1. A quantizer for quantizing a video signal received from a radar device for each processing unit in a distance direction, and a correlation gate centered on a predicted position based on beam angle and distance information obtained by the radar device. And a gate circuit for passing only the video signal in the correlation gate generated by the correlation gate generator among the video signals quantized by the quantizer, A correlator that correlates the gate circuit output with the predicted position based on beam angle and distance information, a smoother that smoothes the correlation result obtained by the correlator to observe the target position, and a search for the radar device Clock generating means for generating a clock signal having a cycle shorter than time, and a clock generated by the clock generating means for a target position obtained by the smoother A position change amount calculating means for obtaining a position change amount in a signal cycle, and an observation position obtained by the smoother for the position change amount obtained by the position change amount calculating means in a clock signal period generated by the clock generating means. An automatic tracking device including a predicted position generation / update unit that cumulatively adds to and generates / updates a predicted position for the next time. 2. The predictive position generation / updating means, and a selector for selectively deriving the observed position when the target position is observed by the smoother and the predicted position otherwise. And a position storage unit for storing the selection result of the above in the clock signal cycle, and the position change amount calculated by the position change amount calculation means is cumulatively added to the storage position of the position storage unit in the clock signal cycle to obtain the next predicted position. The automatic tracking device according to claim 1, further comprising: a cumulative adder for obtaining 3. The automatic tracking device according to claim 1, wherein the clock generating means sets the clock signal cycle to a cycle in which the search time is an integral multiple. 4. The automatic tracking device according to claim 1, wherein the clock generating means is configured to variably set a clock signal period.