JP6922958B2 - Number counting device and number counting method - Google Patents

Description

The present invention relates to, for example, a number counting device and a number counting method applied to the measurement of the number of bluefin tuna in a cage.

Bluefin tuna, which is one of the main fish species for fish cage farming, has a biological characteristic that its epidermis is weak, and once it is put into a cage, it cannot be touched until it is shipped, so many aquaculture companies Manages the number of fish from the start of fry to shipping by an empirical method.

The counting device and counting method described in Non-Patent Document 1 have been proposed to solve the drawbacks of the density estimation method, the method using an underwater camera, etc. as a conventional measurement method capable of grasping the number of farmed fish in real time.

The method described in Non-Patent Document 1 focuses on the swimming behavior of bluefin tuna orbiting in a cage in a certain direction, and the number of bluefin tuna passing through one cross section of the cage and the number of passing fish per unit time. This is a method of finding the total number of bluefin tuna in the cage by multiplying the lap times of.

Journal of Nippon Suisan Kaisha "Fisheries Engineering" Vol.54 No.3. Pp215-221 2017 ・

The method described in Non-Patent Document 1 has an advantage that the number of fish can be measured with higher accuracy than the previous method. In this method, a multi-channel image like a normal fish finder from a multi-transmission / reception sonar is displayed on the screen of a PC (personal computer). However, in order to remove the false image (appropriately called ghost) caused by the reflected signal from other channels, the individual reaction images whose measurement time and distance match in the images of each channel displayed on the screen are compared. , The process of capturing an image with a strong individual reaction and removing the reaction that does not have a strong individual reaction as a ghost is performed manually. As a result, there are problems that the processing time becomes long and the processing varies among workers and the accuracy deteriorates.

Therefore, an object of the present invention is to provide a number counting device and a number counting method in which such a problem is solved.

The present invention includes a multi-transmission / reception sonar in which a plurality of ultrasonic wave transmitters / receivers are arranged to have a plurality of ultrasonic wave transmission / reception channels.
A fish number calculation unit that calculates the number of fish that pass through an acoustic curtain formed by multiple ultrasonic wave transmitters and receivers of a multi-wave sonar per unit time, and
A swimming speed calculation unit that calculates the swimming speed of fish,
It is equipped with a number calculation unit that calculates the total number of fish from the number of fish calculated by the number calculation unit and the swimming speed obtained by the swimming speed calculation unit.
It is a tail number measuring device characterized by performing a ghost removal process that leaves the largest echo among echoes of substantially the same distance on adjacent channels in the received signal of the multi-transmission / reception sonar.
Further, the present invention is a method for measuring the number of fish that performs such processing.

According to at least one embodiment, the number of tails can be measured automatically and with high accuracy by removing the ghost in the received signal of the multi-transmission / reception sonar. The effects described here are not necessarily limited, and may be any of the effects described in the present specification or an effect different from them.

FIG. 1 is a block diagram showing an outline of an entire system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a flow of an example of the process of measuring the number of fish fish. FIG. 3 is a flowchart showing the flow of another example of the process of measuring the number of fish fish. FIG. 4 is a schematic diagram for explaining the multi-transmission / reception sonar. FIG. 5 is a flowchart for explaining the processing of the received signal of the multi-transmission / reception sonar. FIG. 6 is a waveform diagram for explaining the processing of peak detection in each channel. FIG. 7 is a schematic diagram showing a state in which a fish passes through an acoustic curtain by a multi-wave transmission / reception sonar. FIG. 8 is a schematic diagram showing an image of echoes of adjacent channels. FIG. 9 is a waveform diagram for explaining signal processing for ghost removal. FIG. 10 is a waveform diagram for explaining the evaluation of continuity. FIG. 11 is a schematic diagram showing an example of an image of the detected fish. FIG. 12 is a graph showing an example of the number of passing fish in each lane. FIG. 13 is a schematic diagram for explaining a state in which tuna swims in a vertical cross section and a horizontal cross section of a cage. FIG. 14 is a schematic diagram showing an echogram of a transmitter / receiver and an echogram of one channel of a multi-transmission / reception sonar. FIG. 15 is a schematic diagram showing the echogram of ch16, the echogram of ch6, and the result of the correlation analysis. 16A and 16B are a schematic diagram of a tuna viewed from above and a waveform diagram of an example of an echo. FIG. 17 is a graph showing an example of the frequency (frequency) distribution of the distance difference. FIG. 18 is a schematic diagram showing the relationship between the transmitter / receiver and the fish. FIG. 19 is a graph showing an example of the frequency distribution of fish body length obtained by the body length measuring method.

Hereinafter, embodiments and the like of the present invention will be described with reference to the drawings. The embodiments and the like described below are suitable specific examples of the present invention, and the contents of the present invention are not limited to these embodiments and the like.

FIG. 1 shows an outline of the entire system. The tail counting system 1 includes an ultrasonic wave transmitter 2 and a receiver 3. The transmitter 2 and the receiver 3 are provided for a plurality of channels (for example, 15 channels) so as to have different directional characteristics, and the transmitter 2 and the receiver 3 provide a multi-wave transmission / reception sonar. It is configured. A transmission signal is supplied from the transmission circuit 4 to the transmitter 2, and the ultrasonic transmission signal is radiated into water. The receiver 3 receives a reflected signal (appropriately referred to as an echo) corresponding to the transmitted signal, and the received signal is supplied to the receiving circuit 5.

The multi-transmission / reception sonar has a performance for measuring bluefin tuna (hereinafter, simply referred to as tuna or fish as appropriate) swimming in the cage 8 of a predetermined determination without overlooking. That is, the frequency, distance resolution (pulse width) and beam width that enable individual identification of swimming tuna are set, the number of pulse shots that can capture individuals swimming at high speed is set, and the vertical cross section of the vagina is covered. It is equipped with an array of transmitters and receivers that form a capable acoustic curtain.

A calculation unit 6 composed of a microcomputer or the like is connected to the transmission circuit 4 and the reception circuit 5. The calculation unit 6 is operated by software (program) and has a function represented by blocks of a passing fish fish number calculation unit 7a, a swimming speed calculation unit 7b, and a fish fish number calculation unit 7c. The measurement result is output by the processing of the calculation unit 6. Although not shown, a storage (recording) device, a display device, and the like for outputting measurement results are provided.

An example of the flow of processing for measuring the number of fish fish is shown in the flowchart of FIG.
Step ST1: Count the number of fish passing through the acoustic curtain using the received signal of the multi-transmission / reception sonar.
Step ST2: Calculate the orbiting speed of the fish using Pinger.
Step ST3: The total number of fish is calculated from the orbiting speed of the fish and the number of fish passing through the acoustic curtain obtained in step ST1.

A pinger (ultrasonic oscillator) is used to determine the time it takes for a tuna to orbit a cage, that is, the orbital time. As an example, a small pinger is inserted into the body of mackerel, which is the food for tuna, and the tuna is fed with the small pinger so that the tuna is taken into the body of the tuna in a non-contact manner.

The method of obtaining the swimming locus based on the Pinger signal is to receive the Pinger signal transmitted from the swimming fish by the receivers installed at four places in the cage, and to obtain the position obtained from the reception time difference of each signal. The position of the fish is obtained in real time from the intersection of the lines. The frequency of Pinger is, for example, 62.5 kHz, and the transmission interval is 1 time / s. Pinger is attached to several fish. The swimming behavior of tuna swimming in the cage can be received and measured in real time every second, and the swimming trajectory is required. From this result, it was found that the tuna orbits in the cage almost regularly counterclockwise. Therefore, from the orbital loci obtained from these pingers, the swimming locus of the fish was extracted for each orbital radius, and the relationship between the orbital radius and the orbital time was investigated. It was found that it is represented by the following linear regression equation with a high correlation coefficient.

y (i) = ax (i) + b
y (i): Orbit time (s) of the i-th lane
i: Lane number every 1 m from the center of the cage to the outer circumference x: Distance from the center of the cage to the outer circumference (circumferential radius) (m)

The number of fish that passed through one section of the cage was calculated as the number of fish that passed per unit time, and the lap time in each lane obtained earlier was multiplied by the number of fish that passed per unit time, and this was calculated as the number of fish that passed in each lane. The total number of tuna in the cage Q can be obtained by totaling. This equation is shown below.

Q = Σ (m (i) / t × y (i)

In the above equation, (m (i)) represents the number of fish passing t time in the i-th lane, and t is the measurement time (s). Further, Σ indicates that the sum of (i = 1) to (i = n) is to be obtained, where the lane number is (1, 2, ..., N).

FIG. 3 is a flowchart showing another example of the flow of processing for measuring the number of fish fish. In another example, the lap time is obtained from the received signal of the multi-transmission / reception sonar without using a pinger.
Step ST11: Count the number of fish passing through the acoustic curtain using multi-transmission and reception sonar.
Step ST12: Calculate the orbiting speed of the fish using multi-transmission and reception sonar.
Step ST13: The total number of fish is calculated from the orbital speed of the fish and the number of fish passing through the acoustic curtain.

Further, an embodiment of the present invention will be described. As shown in FIG. 4, the multi-transmission / reception sonar 9 is designed to measure tuna swimming in a cage 8 having a predetermined determination. As an example, the specifications are as described in Non-Patent Document 1. That is, the frequency is 460 kHz in a high frequency band capable of high resolution, 0.064 ms (distance resolution 4.8 cm) as a pulse width having a distance resolution capable of identifying individual tuna, and a beam for exploration without overlooking one cross section. The number of pulse shots is set to 20 times / s so that the reflected echo from the tuna with a width of 5 degrees and a swimming speed of about 1 m / s can be sufficiently received.

A multi-transmission / reception sonar 9 in which 15 transmitters / receivers having these functional elements are arranged in a fan shape is installed inside the cage 8, and one section of the cage is made into a so-called acoustic cross section by ultrasonic waves transmitted from the multi-transmission / reception sonar 9. It is partitioned by 10 (referred to as an acoustic curtain) so that the number of orbiting tuna that pass through the acoustic curtain 10 can be measured without overlooking.

In the multi-transmission / reception sonar 9, the directional characteristics of the transmitter / receiver are set in order to reliably capture the echo from the fish. Therefore, echoes from the same fish are measured on multiple receivers. The direction of the fish has the highest echo intensity. Echoes other than the direction of the fish are ghosts. In order to automatically count by a computer or the like, it is necessary to remove the ghost and detect it as a single fish.

Furthermore, the measured data also includes noise (echo from other than fish, electrical noise, etc.). It is necessary to remove noise and detect only echoes from fish. In this system of one embodiment, the transmission signal is transmitted 20 times per second. In the case of echoes from fish, echoes are measured continuously, but in the case of noise, it is highly possible that the echoes exist only once.

In one embodiment of the present invention, in consideration of the above points, the received signal of the multi-transmission / reception sonar is processed by the processing as shown in the flowchart of FIG.
Step ST21: A peak is detected from the echo of the received signal measured in each channel (receiver).

Step ST22: When there are peaks in adjacent channels at approximately the same round trip distance, only the echo of the largest channel is left as an echo from one fish (ghost removal).
Step ST23: If a peak exists in the same round-trip distance even in the previous transmission signal, it is regarded as an echo from one fish (echo continuity evaluation). That is, peaks having substantially the same distance as the previous transmission signal are connected.

Step ST24: It is determined whether or not the number of transmissions linked as a peak in the process of step ST23 is equal to or greater than the threshold value. If it is less than the threshold value, the echo is determined to be noise, and the process returns to the first step ST21.
Step ST25: If it is determined in step ST24 to be equal to or greater than the threshold value, the position of the fish is calculated from the detected fish channel and distance.

Step ST26: Calculate the number of fish passing through the acoustic curtain per unit time for each distance (that is, for each orbital lane) from the center of the cage (the center in the orbital trajectory of the tuna obtained from Pinger).
Step ST27: The number of fish in the entire cage is calculated from the orbiting speed and the number of passing fish for each distance from the center of the cage.

FIG. 6 is for explaining the process of peak detection in step ST21, where the horizontal axis is the distance and the vertical axis is the magnitude of the echo. FIG. 6 shows the waveform of the received signal of a certain channel. The threshold value as shown by the broken line is set. As the threshold value, an absolute value or a constant multiple of the overall average value is used. In the example of FIG. 6, two peaks having a value equal to or higher than the threshold value are detected. Although the echo is shown as an analog waveform in FIGS. 6, 9 and 10, the arithmetic unit 6 converts the received signal into a digital signal and processes it by digital signal processing.

FIG. 7 shows an example of the acoustic curtain 10 by the multi-transmission / reception sonar 9. In the multi-transmission / reception sonar 9, for example, 15 transmitters / receivers are arranged in a fan shape, and the transmission / reception path of the transmitter / receiver having horizontal directional characteristics is ch (channel) 1, for example, an interval of 5 °. The transmission / reception path having directional characteristics in the vertical direction is defined as ch2, and hereinafter, ch3, ch4, and so on. .. .. , Ch15 is set. Therefore, the acoustic curtain 10 extending in an angular range of 70 ° from the horizontal position is configured as a whole. These numerical values are examples, but the directional characteristics, the number of channels, etc. that can reliably capture the echo from the fish are set. Further, the distance of the detection range of the acoustic curtain 10 is set according to the radius of the cage. For example, when the radius of the cage is 20 m, the multi-transmission / reception sonar 9 may perform detection based on echo in a range slightly larger than 20 m or 20 m.

As shown in FIG. 7, when the tuna passes through the acoustic curtain 10, there are echoes from the same tuna on a plurality of adjacent channels. In order to remove ghosts, echoes (ghosts) having relatively weak reflections are removed (process in step ST22). FIG. 8 shows an image of echoes of adjacent channels such as ch3, ch4, ch5, ch6, and ch7. Like the fishfinder, the vertical direction indicates the distance and the horizontal direction indicates the time. In addition, the shade represents the magnitude of the echo. The dark part indicates that the echo is larger (stronger reflection) than the light part. In this example, among the echoes generated at substantially the same distance, the echo of ch5 is the largest, so the echoes other than ch5 are determined to be ghosts.

FIG. 9 shows ghost removal signal processing. The echoes of ch3 to ch7 are shown. Among the echoes generated at almost the same distance, the echo with a relatively large level (ch5 echo in this example) is determined to be a true echo, and the other echoes are determined to be ghosts.

Next, the evaluation of continuity performed in step ST23 will be described with reference to FIG. FIG. 10 shows the echo waveform of channel ch5, the vertical axis represents time (s), and the horizontal axis represents reciprocating distance (m). Since transmission is performed 20 times per second, the time interval is 0.05 seconds. If there is a peak at the same round-trip distance of the previous one, connect it as a single fish. That is, in the case of a certain threshold value (eg, set within the range of 5 to 20 times), the number of times of continuous transmission capable of continuously capturing the peak is detected as one fish. Noise can be removed by such processing. That is, in the case of an echo from a fish, the echo is measured continuously, but in the case of noise, it is highly possible that the echo exists only once. Then, as shown in the image shown in FIG. 11, the echo of ch5 is detected as a single fish.

The position of the fish is calculated from the detected fish channel and distance (step ST25). The number of passing fish per unit time for each distance (for example, each lane set in 1 m units) from the center of the cage (for example, the center in the circumference of the tuna) is calculated (step ST26).

By multiplying the lap time (s) of each lane by the number of passing fish per unit time that has passed through the acoustic curtain obtained by the multi-wave sonar, the number of passing fish for one lap of tuna in each lane can be obtained. .. FIG. 12 shows this result as the number of passing fish in each lane. Furthermore, the number of existing tuna in the cage can be obtained by adding up the number of passing tuna in each lane. The above processing is performed by the passing fish number calculation unit 7a of FIG.

Then, using the orbiting speed for each distance (lane) from the center of the cage obtained from the data of Pinger by the swimming speed calculation unit 7b, the fish fish number calculation unit 7c calculates the total number of fish in the entire cage by the above formula. Calculate (step ST27).

According to the above-described embodiment of the present invention, the ghost is removed by processing by a computer and software as compared with the work of visually observing the display image of the echo obtained by the multi-transmission / reception sonar and removing the ghost. This makes it possible to prevent double counting and measure the number of fish with high accuracy. In addition, the working time can be shortened.

In the present invention, speed measurement can be performed using a multi-transmission / reception sonar without using a pinger. The state in which the tuna swims in the vertical and horizontal cross sections of the cage is shown as shown in FIG. It is swimming at a vertical depression angle of 25 °.

Two multi-transmission / reception sonars 9a and a transmitter / receiver 9b are arranged at a horizontal distance of 1 m. On the other hand, the multi-transmission / reception sonar 9a has 15 transmitters / receivers (ch1 to ch15) arranged in a fan shape, similarly to the multi-transmission / reception sonar 9 of one embodiment. The transmitter / receiver 9b is set at the same angle (directional characteristic) as ch6 of the multi-transmission / reception sonar 9a. The channel of the transmitter / receiver 9b is referred to as ch16. The swimming speed can be calculated from the echoes of ch6 and ch16.

That is, the time difference passing through ch16 and ch6 is t, and the distance difference is dr. The swimming speed Vf is (Vf = moving distance / t) (m / sec), and the moving distance is calculated by ^{√ (1 + dr 2).} √ means the square root of (1 + dr ^2).

FIG. 14 shows an example of echoes of ch16 (transmitter / receiver 9b) and ch6 (multi-transmission / reception sonar 9a). The horizontal axis is time and the vertical axis is range (m). When these images are referred to as echograms, the echogram of one ch6 is represented by E6 (r, t), and the echogram of ch16 is represented by E16 (r, t).

With reference to the echogram E6 (r, t) of ch6, how much time difference (τ) and distance (dr) the same image has is evaluated by correlation analysis. From the values of dr and τ, which are the maximum values of R in the following equation, the distance difference between fish and the movement time of fish are calculated, respectively.

Although the distance difference and the time difference are measured using the two-dimensional correlation analysis, it can be changed to the time difference at the start of sound echo or the time difference at the peak.

FIG. 15 shows the echogram of ch16, the echogram of ch6, and the result of the correlation analysis. The figure at the bottom of FIG. 15 is the result of the correlation analysis, and from the maximum value, the movement time is 0.95 seconds and the change in distance is 0.096 m. From this result, the speed is calculated to be 1.06 m / s.

Next, an application example of the present invention will be described. The first application example is the measurement of the body width of a fish such as tuna. FIG. 16A is a view of the tuna from above, and the tuna has a swim bladder 21 in the central part of the body. When the ultrasonic waves of the multi-transmission / reception sonar similar to the above are incident from the side of the tuna, as shown in FIG. 16B, echoes are generated twice due to the reflection of the body surface and the hollow. The vertical axis of FIG. 16B is the interval of transmission time in a certain channel, and the horizontal axis is the range (m). Taking advantage of this, the body width can be obtained by doubling the distance difference between the multiple reflections of the echo in which the multiple reflections occur. For fish without a swim bladder, the body width can be determined by the distance difference between multiple echo reflections.

FIG. 17 shows an example of the frequency (frequency) distribution of the distance difference obtained in this way. By finding the average of the distance differences, the average body width can be found. For example, an average body width of 35.6 cm is required.

A second application example of the present invention will be described. The second application example is a method for estimating the body length of tuna. As shown in FIG. 18, the time at which the reflection of the fish is measured by the ultrasonic wave transmitter / receiver depends on the orbiting speed and the body length of the fish. Therefore, the body length can be estimated by removing the component depending on the orbiting speed from the time when the reflex of the fish is measured. Expressed as an expression, it is as follows.

Fish length L (m) = v × l / 20-d (m) × tan (θ / 2) × 2

l: Number of pings for 1 fish
v: Swimming speed of fish (m / s)
d: Distance from the transmitter / receiver to the fish (m)
θ: Direction angle of transmitter / receiver

FIG. 19 is a graph showing an example of the frequency distribution of fish body length obtained by such a body length measuring method. The horizontal axis shows the body length (m), and the vertical axis shows the frequency. When the body length was estimated from this data, 1.04 m was obtained as the average fish body length.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned one embodiment, and various modifications based on the technical idea of the present invention are possible. For example, as a fish species, it can be applied to fish other than tuna such as yellowtail, amberjack, and salmon. Further, the configurations, methods, processes, shapes, materials, numerical values, etc. mentioned in the above-described embodiments are merely examples, and different configurations, methods, processes, shapes, materials, numerical values, etc. may be used as necessary. May be good.

1 ... tail count system, 2 ... transmitter / receiver, 3 ... receiver, 4 ... transmitter circuit,
5 ... Reception circuit, 7a ... Passing fish number calculation unit, 7b ... Swimming speed calculation unit,
7c ・ ・ ・ Fish tail number calculation unit, 8 ・ ・ ・ Fish cage, 9 ・ ・ ・ Multi-transmission / reception sonar,
10 ... Acoustic curtain

Claims (8)

A multi-wave transmission / reception sonar in which a plurality of ultrasonic wave transmitters / receivers are arranged to have a plurality of ultrasonic wave transmission / reception channels.
A fish number calculation unit that calculates the number of fish that pass through an acoustic curtain formed by a plurality of ultrasonic wave transmitters and receivers of the multi-wave sonar per unit time, and a fish number calculation unit.
A swimming speed calculation unit that obtains the swimming speed of the fish,
The number of fish calculated by the number calculation unit and the total number of fish calculated from the swimming speed obtained by the swimming speed calculation unit are provided.
A tail number measuring device characterized by performing a ghost removal process that leaves the largest echo among echoes of substantially the same distance on adjacent channels in the received signal of the multi-transmission / reception sonar. The tail number measuring device according to claim 1, wherein the peaks of echoes having substantially the same distance to the previous transmission signal are concatenated, and when the number of concatenations exceeds the threshold value, noise is removed by determining that the fish is a fish. .. The swimming speed calculation unit receives signals from a fish to which an oscillator is attached by a plurality of receivers, detects the position of the fish, and calculates the swimming speed of the fish from the detected position of the fish. Or the number measuring device according to 2. The swimming speed calculation unit is provided with another transmitter / receiver at a position horizontally separated from the multi-transmission / reception sonar by a predetermined distance, and is detected by the multi-transmission / reception sonar and the other transmitter / receiver and echoes the fish. The fish number measuring device according to claim 1 or 2 , wherein the swimming speed of the fish is calculated from the above. The fish number measuring device according to any one of claims 1 to 4 , wherein the body width of the fish is measured from the distance between two peaks of the fish echo of the multi-wave sonar. The fish number measuring device according to any one of claims 1 to 5 , wherein the body length of the fish is estimated by calculating the time when the echo of the multi-transmission / reception sonar exists and considering the orbiting speed. An acoustic curtain is formed by a multi-wave sonar made by arranging a plurality of ultrasonic wave transmitters / receivers and having a plurality of ultrasonic wave transmission / reception channels, and the number of fish that pass through the acoustic curtain per unit time is calculated. Calculation steps and
The swimming speed calculation step for obtaining the swimming speed of the fish, and
It has a number of fish calculated by the step of calculating the number of fish and a step of calculating the total number of fish from the swimming speed obtained by the step of calculating the swimming speed.
A method for measuring the number of tails, which comprises performing a ghost removal process that leaves the largest echo among echoes of substantially the same distance on adjacent channels in the received signal of the multi-transmission / reception sonar. The method for measuring the number of fish according to claim 7, wherein the peaks of echoes having substantially the same distance to the previous transmission signal are concatenated, and when the number of concatenations exceeds the threshold value, noise is removed by determining that the fish is a fish. ..

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