JPS6366461A - Aquatic animal monitor - Google Patents

Abstract

PURPOSE:To secure the safety of an inflow water at a purification plant and a sewage treating plant, by detecting an abnormal behavior of fish from a gravity center position and speed of fish. CONSTITUTION:A camera device 3 recognizes an image of fish 11 in a water tank 1 and sends an electric signal corresponding to the brightness of a pixel recognized to an image processor 4. The processor 4 recognizes fish 11 based on image information thereof 11 obtained with the device 3 to calculate the gravity center G thereof 11. An output signal of the gravity center G from the processor 4 is transmitted to a central arithmetic unit 6 to compute a moving speed of the fish 11 from a signal of the gravity center G. This processing is repeated for a specified time to compute a distribution of gravity centers and speeds of the fish 11. Here, when the distribution thus obtained gives a difference above a deviation preset in comparison with the normal distribution, the behavior of the fish 11 is determined to be abnormal and the results of the judgement are sent to an alarm 8. Thus, the behavior of the fish 11 is monitored continuously and quantitatively according to the gravity center position and the moving speed thereof thereby securing the safety of water at a purification plant or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aquatic animal monitoring device for monitoring the contamination of toxic substances in raw water of a water treatment plant or inflowing sewage of a sewage treatment plant.

[Prior art]

At the water treatment plant, in order to monitor whether or not poisonous substances have been mixed into the raw water, a portion of the raw water is introduced into an aquarium where aquatic animals such as crucian carp, carp, dace, tanager, rainbow trout, and oysterfish are raised in this aquarium. There is. That is, when a poisonous substance is mixed into the raw water, the inflow of the poisonous substance into the raw water is monitored using the phenomenon that the fish behave abnormally or die. Also,
Sewage treatment plants need to know whether legally prohibited toxic substances have entered the influent sewage, so they rely on intermittent manual water quality analysis.

As described above, monitoring of toxic substances in water currently relies on human visual observation and analysis. As a result, continuous monitoring and early detection were not possible, and countermeasures such as stopping water distribution to customers had to be taken late.

One way to monitor fish is to detect fish in an aquarium from the top of the tank using an industrial TV camera (ITV) and process the image (Reference: 36th Gold Country Waterworks Research Presentation, Lecture Collection P464)
~466) have been devised. According to this method, when a fish floats on the water surface with its belly on its side, the fish can be recognized as an ``independent bright spot of a certain size or more'', and the high brightness area of the fish near the water surface and the It is stated that by extracting only the changes in light due to the unevenness of the surface, the background can be sorted out and the behavior of the fish can be determined.

[Problem that the invention seeks to solve]

A method of detecting fish in an aquarium from the top of the tank using ITV and image processing (36th Gold Country Waterworks Research Presentation, Lecture Collection P464)
~P466) When the raw water flowing into the aquarium is cloudy, it is not possible to recognize fish by binarization with a fixed threshold value, so floating binarization is necessary, but in that case, the threshold value can be changed. It is necessary to do so, and no one knows how to change it.

Furthermore, although it is stated that this method can be used to recognize fish, there is no mention of a method for detecting abnormalities in fish.

An object of the present invention is to provide an aquatic animal monitoring device that determines the presence or absence of toxic substances in water by objectively and continuously monitoring the movement of fish.

[Means to solve problems]

The present invention includes an imaging device that images the water surface including aquatic animals in an aquarium, and a first imaging device that alternately stores images obtained at different times with the imaging device. a second memory; and a second memory; a first means for obtaining a difference between images in a second memory; a second means for obtaining a ternary logical value by comparing the difference image with a predetermined threshold; It consists of a means for determining the existing position and a center of gravity position and a moving speed from that position, and a means for determining an abnormality from the center of gravity position and moving speed.

[Effect]

The imaging device converts images of fish kept in an aquarium into brightness signals. This luminance signal is digitized and captured into the image memory at different times. These fish images in the image memory are subjected to differential processing to obtain a differential image. By converting this differential image into three values, the fish before and after movement are recognized, and the center of gravity of each fish is calculated. Furthermore, the moving speed of the fish is calculated from these center of gravity positions.

In this way, the movement of the fish is detected based on its center of gravity position and speed. Abnormal behavior can also be detected by measuring these distributions and comparing them with normal patterns.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. 1 is an aquarium for breeding fish, and water is constantly supplied.

The water to be supplied is raw water at a water treatment plant, inflow sewage at a sewage treatment plant, and river water when monitoring toxic substances in a river. Fish 11 are kept in an aquarium 1. Usually, a plurality of fish are kept, but one fish is used in this example for ease of explanation and understanding.

Let's take the case of one fish as an example. The fish 11 are those that live in the water supply 6, such as crucian carp, carp, etc.
These include Japanese dace, Japanese tanager, and Oikawa. Lighting device 9
illuminates fish 11 in tank 1.

Since the present invention applies image processing technology, uniform illumination is required. For this reason, a back screen 2 corresponding to a light scattering plate made of ground glass, white acrylic, or the like is provided between the lighting device 19 and the aquarium 1. back screen 2
It also has the role of recognizing the fish 11 with good contrast. Namely.

By making the background white using the back screen 2 and making the fish black, it is possible to recognize the fish with good contrast. The lighting device 9 receives a lighting instruction and a light amount instruction from the lighting control device 10 .

Imaging device! A is an industrial television camera (ITV) that recognizes the image of the fish 11 in the aquarium 1 and converts it into a video signal.
is used. In other words, the brightness of the pixel to be recognized is 11
Emit electrical signals with different output voltages depending on the degree of
The electrical signal output from the imaging device 3 is transmitted to one image processing device 4.
The 0 image processing device 4 sent to is an imaging device! For 3,
It outputs a horizontal synchronization signal and a vertical synchronization signal to control the timing of imaging.

The image processing device 4 is an image processing device that recognizes the fish 11 based on the image information of the fish 11 obtained with the imaging bag [3] and calculates its center of gravity G! The detailed structure and operation of the centroid calculation method in No. 4 will be described later.0 A monitor 5 is connected to the image processing device 4, and displays an ITV image of the fish and the results of image processing of this image.

The signal of the center of gravity G output from the image processing device 4 is as follows.

It is transmitted to the central processing unit 6. Although the details will be explained later, the central processing unit 6 calculates the moving speed V of the fish 11 from the signal of the center of gravity G of the fish 11. This process is repeated for a predetermined period of time, and 1 fish
Calculate the distribution of the center of gravity G and velocity V of 1.

The central processing unit 6 has a memory, and the fish 11 is stored in the memory.
The velocity distribution and the center of gravity position distribution when the state is normal are stored, and these normal values are compared with the measured values (actual measured values) obtained online.

That is, if the movement speed V of the fish 11 is measured for a predetermined period of time and the distribution differs from the normal distribution by more than a preset deviation, the 0 judgment result that determines that the movement of the fish 11 is abnormal is , is sent to the alarm device 8.

When the alarm device receives an abnormal signal, it sounds an alarm or outputs a voice message to prompt the supervisor to investigate the water quality.

Note that the normal values of the distribution of the gravity center position and moving speed of the fish 11 can be corrected or changed according to environmental conditions such as the type of fish and water temperature.

This correction and change operation can be performed manually or automatically. For example, when making corrections for changes in water temperature, first.

The water temperature in the water tank is measured with a water thermometer 13, and this temperature measurement value is sent to the central processing unit 6 to correct the center of gravity position and movement speed distribution.

The central processing unit 6 includes a display device 7. A keyboard 12 is connected, and operations such as displaying the calculation results of the fish's center of gravity position and speed distribution, correcting the normal values, and initializing the processing time and criteria for determining behavioral abnormalities can be performed.

FIG. 2 shows the configuration of the image processing device 4. An input/output control device 401 captures an image signal from an imaging device using a horizontal synchronization signal and a vertical synchronization signal. After capturing, AD conversion is performed and the data is stored in grayscale image memories 402 and 403.

The capturing period Δt of one image is given from the central processing unit 6. One image obtained every period Δ is.

They are stored alternately in memories 402 and 403.

For example, the grayscale image memories 402 and 403 have horizontal and vertical dimensions of 256 pixels x 236 pixels, and one pixel is 8 pixels.
Consists of bits. That is, each pixel had 256 gradations.

The luminance information of the pixel in the i row and j column of the memories 402 and 403 is expressed as H'(i, Jt t)t H(iy jy t+Δt
), this information will be information before the fish 11 moves and information after it moves during the time Δt. The interval time Δt was approximately 0.1 seconds to 5 seconds.

The luminance information H(i, j, t) and H(is Je t+Δt) taken into the grayscale image memories 402 and 403 are subjected to image processing, and finally the center of gravity position itG of the fish 11 before and after the movement is calculated. do.

The difference bag R404 stores the luminance information H(i, j, t) and H(L jt
The difference is calculated from t+Δt). That is, the difference calculation according to equation (1) is performed for all pixels to calculate a difference image S (1+js t), which is stored in the grayscale image memory 405.

S (i, j, t) = H (i, j, t + Δt) - H (iy
, Lt)...(1) A difference image is calculated to extract a moving object. Here, a high value of brightness represents a bright object, and a low value represents a dark object. Let f be the brightness of the fish, and W be the brightness of the water. If the fish is black and the water background is white, the time t in the difference image
The part of the water that has the same brightness at time t + Δt is subtracted, and the brightness takes a value close to O. The image of the fish at time 0 time t + Δt is changed from the dark brightness f of the fish to the bright brightness W of the water at time t.
is subtracted, so f-W<O and takes a negative value.

On the other hand, the image of the fish before moving at time t is t+Δ
Since the dark brightness f of the fish at time t is subtracted from the bright brightness W of water at time t, W-f>O, which takes a positive value.

In this way, the difference image 4 obtained by the difference device 404
05 is input to the ternarization device 406.

The ternarization device 406 performs ternarization calculations according to equations (2), (3), and (4), and stores the results in the image memory 407. Let Ls be a threshold value for ternarization.

When S(1*Jtt)<-Ls, S(x*,), t)=
1...(2) When S(i-jet)>Ls, 5(itjtt)=1...
・(3) When −Ls≦S(i+Jyt)≦Ls, S (x + J v t ) = O...(4) The value of the threshold Ls is the difference W- between the brightness W of the water and the brightness f of the fish. f'
Choose from more than that.

In the 3' value conversion device 406, according to equations (2), (3), and (4), the brightness of the fish at time t takes a value of -1, and the brightness at time t+
The fish at Δt has a brightness of 1, and the background water has a brightness of 0.

The centroid calculation bag [408 calculates the centroid G of each image having values of -1 and +1. Each calculation result Gn(1wJy
tL Gp(ltj+t) is sent to the central processing unit 6.

This center of gravity is the number of pixels N in the area where “1” exists in the binarized image.
, is calculated based on the coordinates (xt, YJ) of the "1" existing region.

In addition, the input control device 401. Grayscale image memory 402.4
03. Difference image memory 405. The digital signal from the ternary storage image memory 407 can be output to the monitor 5 via the selector 410.

FIG. 3 is a diagram showing the ternarization process of fish by the image processing device 4. Figure 3 (a), (b).

(Q) is a grayscale image of the fish at time t, and time t
The grayscale image of the fish at +Δt, the position before and after the fish is moved by 3
This is a valued image. In FIG. 3(c), x, y, and z represent the water part of the background, the fish at time t, and the fish at time t+Δt, respectively. The numbers in the diagram represent the respective brightnesses.

FIG. 4 shows the configuration of the central processing unit 6.

The center of gravity G n (x p
jetL Gp(xejst) is one centroid storage device 601
After being stored in , the moving speed calculation device 602 calculates the moving speed V (t) using equation (6).

v(t)”1Gp(1+J*t)-Gn(1*jt
t) I/Δt...(6) In this way, 1 hour 1.1+Δt, t+2・at...
..., the moving speed V of each fish at t+k・at
(t); v(t+Δt), v(t+2・at)...
..., V(t+k·at) is calculated for each time Δ using the following formula. These calculated moving speeds V (t), the zero center of gravity stored in the moving speed storage device 603, and the data in the moving speed storage devices 601 and 603 can be displayed on the display 7 via the selector 600.

The determination circuit 604 stores the distribution of the center of gravity position of the fish 11 when it is normal;
The moving speed distribution is stored. The center of gravity and moving speed storage devices 601 and 803 store the center of gravity position I input in real time.
I G p y G n , the moving speed V(1) is stored in time series, and at the same time, the center of gravity position distribution G(i
y at t), calculate the moving speed distribution V (t),
It is output to the determination circuit 604.

The determination circuit 604 compares the moving speed distribution V (t) and the center of gravity position G (x t jt T) with the normal state, and when the deviation is large, sends a signal to the alarm output device 605 indicating that an abnormality has occurred. The alarm output device outputs this signal as WI! Output to device 8.

When the center of gravity position and movement speed distribution stored in the determination circuit 604 are normal, they are constantly corrected based on environmental conditions such as water temperature in the aquarium, lighting time zone, season, type of fish and number of fish.

FIG. 5 shows an example of determination based on moving speed.

FIGS. 5(a)-(b) and (c') show the distribution during unit time T when the moving speed V is small, normal, and large, respectively. In this way, the moving speed distribution during a certain time T is obtained, the deviation E from the normal state (b) is calculated, and if the deviation is larger or smaller than the set value EIl, it is determined that there is an abnormality.

If it is determined that the deviation E of the moving speed distribution is small, then the distribution of the center of gravity G (T) of the fish is determined.

In general, fish do not normally sit on the surface of the water, but when they become difficult to navigate at a certain depth, they often position themselves close to the water's surface, with their noses up. As a result, if the moving speed of the fish is slow and the center of gravity of the fish is near the water surface, a strong warning such as a buzzer will be output. If the fish's moving speed is low and the fish's center of gravity is in the correct position, a weak warning such as a chime will be issued.

〔Effect of the invention〕

According to the present invention, since the behavior of fish can be continuously and quantitatively monitored based on the position of the center of gravity and the speed of movement, it is possible to quickly and automatically determine whether or not a poisonous substance has entered the water. Therefore, monitoring of toxic substances in inflow water at water purification plants and sewage treatment plants can be carried out simply and accurately, and water safety can be ensured.

[Brief explanation of the drawing]

1 Wi is an overall configuration diagram of an embodiment of the present invention, FIG.
3, 4 and 5 are detailed views of the embodiment. 1...Aquarium, 3...Industrial television camera, 4...
Image processing device, 6... Central processing unit, 9... Lighting,
11...Aquatic animals (fish).

Claims (1)

[Claims] 1. An aquarium in which aquatic animals are raised to detect poisonous substances in the water, and an imaging device that captures an image of the inside of the aquarium containing the aquatic animals;
first and second memories that alternately store images obtained from the imaging device at predetermined time intervals as grayscale image information; and a second memory that calculates a difference between the images in the first and second memories to obtain a difference image. For each pixel S of the difference image, whether S≧Ls, S≦−Ls, or −Ls<S a second means for performing ternarization of 1, -1, and 0 depending on whether the
Based on the ternarization processing result by the means, the pixel areas of 1 and -1 are set as the positions of the aquatic animals before and after the predetermined time,
a third means for determining the center of gravity on the two existing positions;
An aquatic animal monitoring device comprising: two center of gravity positions; and fourth means for determining poisonous substance contamination from the moving speed determined from the two center of gravity positions.