Nutrient salt supply monitoring and control system for underwater plants

Abstract

To provide a nutrient salt supply monitoring and control system for underwater plants, which allows monitoring based on color information while suppressing the effect of absorption characteristics caused by seasonal, weather-based, or temporal variations in ambient light and seawater quality.SOLUTION: A nutrient salt supply monitoring and control system for underwater plants comprises an underwater camera for capturing images of aquatic plants and a color chart, a hue correction unit for correcting the hue of the image of the underwater plants captured by the underwater camera based on the captured image of the color chart, a nutrient salt supply amount calculation unit for calculating the nutrient salt supply amount to the underwater plants based on the color information of the hue-corrected image of the underwater plants, and a nutrient salt supply unit for supplying nutrient salt to the underwater plants.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a system for monitoring and controlling nutrient supply to underwater plants. [Background technology]

[0002] To mitigate climate change, Direct Air Capture (DAC) technology is being developed to fix atmospheric carbon dioxide using marine algae. In some cases, algae growth can be promoted by fertilizing nutrient components such as nitrogen, phosphorus, and iron in nutrient-poor water, but an excess supply of nutrients can lead to red tides, so it is necessary to control the supply of appropriate amounts at the appropriate time. The following prior art has been proposed in relation to this control:

[0003] Patent Document 1 relates to a method for preventing and recovering discoloration of the nori algae at nori farms by identifying the nutrient salt substances that are causing discoloration of the nori algae at an early stage and applying fertilizer appropriate to the causative substance, and shows that fertilizer is applied based on the measurement of the color of the nori.

[0004] Patent Document 2 is an invention related to a method for growing seaweed, in which seaweed is grown using corroded materials or fish waste and steel slag. It shows the use of an autoanalyzer as a method for controlling the concentrations of nitrogen and phosphorus. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5505374 [Patent Document 2] JP 2015-107061 A Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 describes that the discoloration of the Nori algae is judged by visual inspection, but does not describe a method for photographing the Nori algae. When traveling offshore by boat to visually inspect the Nori algae, or photographing the Nori algae with an above-water or underwater camera, it is difficult to grasp subtle changes in the color tone of the algae, because the ambient light varies depending on the season, weather, time of day, and the presence or absence of a sunset or sunrise, and the light absorption characteristics in the water also vary depending on the seawater quality.

[0007] Patent Document 2 directly measures the concentration of nutrients such as nitrogen and phosphorus, and although it is possible to manage the concentrations of nitrogen and phosphorus, it is not possible to control them. Furthermore, the concentration of nutrients (nitrogen and phosphorus) required by seaweed for growth varies depending on the state of photosynthesis. In other words, since the appropriate concentration varies depending on conditions such as water temperature and sunlight, it is not possible to determine whether there is an excess or deficiency of nutrients by simply measuring the concentration of nutrients in seawater with an autoanalyzer.

[0008] Based on the above, the present invention aims to provide a nutrient supply monitoring and control system for aquatic plants that enables monitoring based on color information that reduces the influence of light absorption characteristics due to environmental light and seawater quality that vary depending on the season, weather, and time of day. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides "a nutrient supply monitoring and control system for underwater plants, characterized by comprising an underwater camera for photographing underwater plants and color samples, a color correction unit for correcting the color tone of the image of the underwater plants photographed by the underwater camera based on the photographed image of the color sample, a nutrient supply amount calculation unit for calculating the amount of nutrients supplied to the underwater plants based on color information of the color-corrected image of the underwater plants, and a nutrient supply unit for supplying nutrients to the underwater plants." Effect of the Invention

[0010] According to the present invention, monitoring based on color information is possible with reduced influence of absorption characteristics due to environmental light and seawater quality that differ depending on the season, weather, and time of day.

[0011] Furthermore, according to the embodiment of the present invention, it is possible to realize nutrient supply control based on the monitoring results. Since the monitoring is not just about the nutrient concentration but also about the growth state of the seaweed itself, which varies depending on conditions such as water temperature and sunlight, it is possible to comprehensively evaluate the excess or deficiency of nutrients, enabling appropriate nutrient supply control. Furthermore, since dirt on the surface of the color sample can be reduced, the maintenance interval can be extended. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing an image of color correction. [Diagram 3] FIG. 13 is a diagram showing an example of a graph for calculating the amount of nutrient salt supply from color information after color correction. [Figure 4] FIG. 5 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. EXAMPLES

[0014] FIG. 1 is a schematic diagram of a nutrient salt supply monitoring and control system for aquatic plants according to a first embodiment of the present invention.

[0015] Underwater plants 10 are growing in the water 32, and a color sample 12 is also placed underwater. An underwater camera 14 photographs the underwater plants 10 and the color sample 12. A weight 36 and a float 38 are connected to the underwater camera 14 to prevent the underwater camera 14 from being carried away by wind or currents, and to prevent the underwater plants 10 and the color sample 12 from moving out of the field of view. An image transmission unit 34 is connected to the float 38, and transmits a captured image signal 40 to an image receiving unit 42 installed in a remote location.

[0016] The image receiving unit 42 provides the photographed image 16 of the color sample and the photographed image 22 of the underwater plant, which are included in the photographed image signal 40 of the underwater camera 14, to the color correction unit 18. The color correction unit 18 corrects the color tone of the photographed image 22 of the underwater plant based on the photographed image 16 of the color sample, and provides the color information 20 of the color-corrected underwater plant to the nutrient supply amount calculation unit 26. The nutrient supply amount calculation unit 26 determines whether the underwater plant 10 is receiving an excess or deficiency of nutrients, and provides a nutrient supply amount signal 24 to the nutrient supply unit 30. The nutrient supply unit 30 supplies nutrients 28 into the water 32 at a concentration and amount corresponding to the nutrient supply amount signal 24.

[0017] The above-mentioned underwater 32 may be fresh water or sea water. In the case of sea water, the underwater plants 10 are seaweed or seaweed. Although various products are commercially available as the color sample 12, it is preferable that the color sample 12 is not a product but has various different colors painted in different areas.

[0018] When the light source is sunlight, which is natural light, the color and brightness of the light differs between daytime and sunset. Also, the color and brightness of the light differs between sunny and rainy days, even at the same time. Therefore, when an underwater plant 10 is photographed by an underwater camera 14 under natural light at different times and dates, there will generally be a difference in color tone of the photographed image 22 of the underwater plant. This difference in color tone occurs not only in the photographed image 22 of the underwater plant, but also in the photographed image 16 of the color sample.

[0019] Furthermore, the color tone of the underwater plant 10 when photographed when the water 32 is highly transparent differs from the color tone of the underwater plant 10 when photographed when the water is green due to proliferation of phytoplankton. This is because the wavelength of light that is absorbed and attenuated in the water 32 differs depending on the water quality. This difference in color tone occurs not only in the photographed image 22 of the underwater plant, but also in the photographed image 16 of the color sample.

[0020] Therefore, in the present invention, the photographed image of the underwater plant 10 is subjected to color correction based on the photographed image of the color sample 12, thereby reducing the influence of natural light and the influence of light absorption in water. This makes it possible to obtain more accurate color information of the underwater plant 10.

[0021] An image of color correction is shown in Figure 2. The color correction unit 18 performs the color correction. Since a computer is used for this process, Figure 1 shows the case where the color correction unit 18 is installed on the land side, which is a remote location, rather than on the sea side. The installation location is not limited to the land side, and it may be an object located on the sea, such as a ship or a large buoy. Since the captured image signal 40 needs to be transmitted wirelessly from the underwater camera 14 to the remote location, an image transmission unit 34 is provided on the underwater camera 14 side, and an image reception unit 42 is provided on the color correction unit 18 side.

[0022] An example of a color correction method in the color correction unit 18 will be described below, but the method is not limited to this.

[0023] The RGB values ​​for each color of the color sample 12 are acquired before the color sample 12 is placed in the water 32. As an example, the RGB values ​​of the colors in one area acquired in the air are R0, G0, and B0, respectively. In contrast, suppose the RGB values ​​of the same area included in the image 16 of the color sample 12 captured by the underwater camera 14 are R01, G01, and B01, respectively.

[0024] Here, assume that equation (1) contains four undetermined coefficients (αR, βR, γR, δR). [Number 1] R0=αR·R01+βR·G01+γR·B01+δR···(1) Since there are four undetermined coefficients, it is theoretically possible to determine the values ​​of these four undetermined coefficients if there are four or more areas of different colors in color sample 12. Similarly, for G0 and B0, if there are four or more areas of different colors in color sample 12, it is possible to determine the values ​​of the four undetermined coefficients (αG, βG, γG, δG, αB, βB, γB, δB) included in equations (2) and (3). [Number 2] G0=αG·R01+βG·G01+γG·B01+δG···(2) [Number 3] B0=αB·R01+βB·G01+γB·B01+δB···(3) By using these determined coefficients (αR, βR, γR, δR, αG, βG, γG, δG, αB, βB, γB, δB), when the RGB values ​​of the photographed image 22 of the underwater plant are R11, G11, B11, it is possible to estimate the RGB values ​​R1, G1, B1 of the underwater plant 10 assumed to be photographed in air using equations (4) to (6). [Number 4] R1=αR·R11+βR·G11+γR·B11+δR···(4) [Number 5] G1=αG·R11+βG·G11+γG·B11+δG···(5) [Number 6] B1=αB·R11+βB·G11+γB·B11+δB···(6) The color information 20 of the underwater plants that has been color-corrected in this manner and output from the color correction unit 18 is provided to a nutrient supply calculation unit 26, which judges whether there is a nutrient deficiency or excess. An example of a method for judging whether there is a nutrient deficiency or excess will be described below, but the method is not limited to this.

[0025] It is known that when seaweed such as nori and wakame lack nutrients, the color of the algae, which should be dark green, turns light green, brown, or yellow. Therefore, it is simple to judge whether there is a nutrient deficiency or excess by the shade of the color.

[0026] Figure 3 is an example of a graph showing the relationship between shading, i.e. brightness, and the amount of nutrient salt supply. Small brightness values ​​on the horizontal axis indicate darker algal color, and large brightness values ​​indicate lighter algal color. The relationship between brightness and the amount of nutrient salt supply slopes upward to the right. A small brightness value, i.e., a darker algal color, indicates that there is a sufficient amount of nutrients, so a small amount of nutrient salt supply is output. Conversely, a large brightness value, i.e., a lighter algal color, indicates a nutrient deficiency, so a large amount of nutrient salt supply is output. Note that while the relationship between brightness and the amount of nutrient salt supply is shown as a straight line in Figure 3 for easy understanding, it may also be a curved line as long as it slopes upward to the right.

[0027] By supplying the nutrients 28 into the water 32 in a concentration and amount according to the nutrients supply amount signal 24 obtained as described above, the aquatic plants 10 can be grown appropriately.

[0028] Although only one underwater camera 14 is shown in FIG. 1, multiple underwater cameras 14 may be provided, and some of them may photograph only the underwater plants 10 or only the color samples 12.

[0029] Although not shown in the figure, an artificial light capable of illuminating the shooting range of the underwater camera 14 may be additionally provided. In this case, the influence of natural light as described above can be reduced. However, even in this case, the wavelength of light absorbed and attenuated in the water 32 may differ depending on the water quality, so it is effective to provide a color correction unit 18 and perform color correction based on the captured image 16 of the color sample. EXAMPLES

[0030] FIG. 4 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a second embodiment of the present invention, in which dirt adhering to the surface of the color sample 12 is removed by using a wiper 44.

[0031] Since the color sample 12 exists in the water 32, it is common for aquatic organisms such as algae to attach to the surface, causing the surface to become dirty over time. In such a case, the color of each area of ​​the surface of the color sample 12 will differ from that before it became dirty, and an inappropriate result will be output in the correction calculation by the color correction unit 18. As a result, the nutrient supply amount calculation unit 26 will output a nutrient supply amount signal 24 that does not represent the concentration or amount of nutrients 28 that should be supplied, making it impossible to grow the underwater plants 10 properly, or there may be an oversupply of nutrients 28 that leads to the occurrence of red tides. To avoid this problem, it is necessary to maintain and manage the surface of the color sample 12 so that it does not become dirty as much as possible.

[0032] Therefore, in this embodiment 2, a wiper 44 is provided that can physically remove dirt adhering to the surface of the color sample 12. By driving this wiper 44 periodically or as needed to remove dirt from the surface of the color sample 12, the calculation of the nutrient salt supply amount calculation unit 26 becomes appropriate, and nutrients 28 of a concentration and amount corresponding to the resulting nutrient salt supply amount signal 24 can be supplied to the water 32. This makes it possible to properly grow the aquatic plants 10 over a long period of time. EXAMPLES

[0033] FIG. 5 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a third embodiment of the present invention, in which ultraviolet lighting 46 is used to reduce the adhesion of dirt to the color sample surface 12.

[0034] The ultraviolet rays 50 emitted from the ultraviolet lighting 46 damage the DNA of aquatic organisms that attach to the surface of the color sample 12, suppressing their attachment and proliferation. If the organism is organic rather than aquatic organisms, the unsaturated bonds in particular can be optically oxidized to alter the organism's properties and suppress attachment. Note that to prevent the color sample 12 itself from fading due to the ultraviolet rays 50 emitted from the ultraviolet lighting 46, it is desirable to place a transparent ultraviolet-blocking resin on the surface of the color sample.

[0035] By periodically or appropriately emitting ultraviolet light 50 from the ultraviolet lighting 46 to prevent dirt from adhering to the surface of the color sample 12, the calculation of the nutrient salt supply amount calculation unit 26 becomes appropriate, and nutrients 28 of a concentration and amount corresponding to the resulting nutrient salt supply amount signal 24 can be supplied to the water 32. This makes it possible to grow the aquatic plants 10 appropriately over a long period of time. EXAMPLES

[0036] FIG. 6 is a schematic diagram of a nutrient salt supply monitoring and control system for underwater plants according to a fourth embodiment of the present invention, in which a color sample 12 is placed on the water surface to reduce adhesion of dirt to the surface.

[0037] Placing the color sample 12 in the air above the water surface rather than in the water can prevent aquatic organisms from attaching to the surface. As a result, the calculations of the nutrient supply amount calculation unit 26 become appropriate, and nutrients 28 can be supplied to the water 32 at a concentration and amount corresponding to the obtained nutrient supply amount signal 24. This makes it possible to grow the aquatic plants 10 appropriately for a long period of time.

[0038] In addition, if the installation position in the air is close to the water surface, splashes may adhere to the color sample 12. If the components of the water 32 are not fresh water but contain a high concentration of salt like seawater, the splashes that adhere to the surface of the color sample 12 dry, and the remaining salt crystallizes and hardens into a white solid. As a result, the color tone of the color sample 12 changes. In such a case, the calculation of the nutrient salt supply amount calculation unit 26 becomes inappropriate. To prevent this, it is desirable to provide the color sample 12 on the water surface with a wiper that removes the splashes that adhere to it or a water washing mechanism that washes away the crystallized salt, or to cover the surface of the color sample 12 with a super water-repellent transparent material that does not adhere to the surface even if splashes are applied to the surface.

[0039] In addition, if it is difficult to photograph the underwater plants 10 and the color samples 12 on the water surface with a single underwater camera 14, it is desirable to have multiple underwater cameras 14, and in Figure 6, the camera that photographs the color samples 12 on the water surface is shown as an underwater camera 48 for photographing in the water surface direction. [Explanation of symbols]

[0040] 10: Underwater plants 12: Color sample 14: Underwater camera 16: Photograph of color sample 18: Color tone correction section 20: Color information of underwater plants after color correction 22: Underwater plant images 24: Nutrient supply signal 26: Nutrient supply calculation section 28: Nutrients 30: Nutrient supply section 32: Underwater 34: Image transmission unit 36: Weight 38: Float 40: Shooting image signal 42: Image receiving unit 44: Wiper 46: Ultraviolet lighting 48: Underwater camera for shooting on the water surface 50: UV rays

Claims

1. A nutrient supply monitoring and control system for underwater plants, comprising: an underwater camera for photographing underwater plants and a color sample; a color correction unit for correcting the color tone of the image of the underwater plant photographed by the underwater camera based on the photographed image of the color sample; a nutrient supply amount calculation unit for calculating the amount of nutrients supplied to the underwater plant based on color information of the color-corrected image of the underwater plant; and a nutrient supply unit for supplying nutrients to the underwater plant.

2. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, A nutrient supply monitoring and control system for underwater plants, comprising a wiper for removing substances adhering to the surface of the color sample.

3. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, A nutrient supply monitoring and control system for underwater plants, comprising an ultraviolet illuminator for treating organisms attached to the surface of the color sample with ultraviolet light.

4. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, A nutrient salt supply monitoring and control system for underwater plants, characterized in that the color sample is placed on the water surface.

5. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, A nutrient supply monitoring and control system for underwater plants, comprising: an image transmitting unit that transmits an image signal captured by the underwater camera; and an image receiving unit that receives the image signal captured by the underwater camera.

6. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, A nutrient supply monitoring and control system for underwater plants, comprising a weight connected to the underwater camera and a float connected to the underwater camera.

7. The nutrient salt supply monitoring and control system for underwater plants according to claim 1, The nutrient salt supply calculation unit calculates the amount of nutrient salt supplied to the underwater plant based on the luminance of the color-corrected image of the underwater plant.

8. The nutrient salt supply monitoring and control system for underwater plants according to claim 7, The nutrient supply calculation unit reduces the amount of nutrients supplied to the underwater plants when the brightness of the color-corrected image of the underwater plants is low, and increases the amount of nutrients supplied to the underwater plants when the brightness of the color-corrected image of the underwater plants is high.

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