Seaweed bed evaluation system and seaweed bed evaluation method

Abstract

The position information acquisition unit 101 acquires position information of a moving body traveling near the water surface. The echo intensity acquisition unit 102 acquires echo intensity for each ultrasonic transmitter / receiver using multiple ultrasonic transmitter / receivers. The algae echo detection unit 103 detects algae echoes from the acquired echo intensity. The height estimation unit 104 estimates the height of the algae. The area calculation unit 105 calculates the area of ​​algae present in the width direction of the moving body based on the position information of the moving body. The algae amount estimation unit 106 calculates the volume of algae present between each piece of position information of the moving body's traveling route based on the area of ​​algae for each piece of position information of the moving body's traveling route and the moving distance of the moving body, thereby estimating the amount of algae.

Description

[Technical field]

[0001] The present invention relates to a seaweed bed evaluation system and a seaweed bed evaluation method. [Background technology]

[0002] Conventionally, there is a technique for measuring and evaluating underwater seaweed beds using an ultrasonic transmitter / receiver. For example, Japanese Patent Laid-Open Publication No. 6-281736 (Patent Document 1) discloses an ultrasonic algae measuring device that includes a transmission circuit, a transmitter / receiver, an amplifier circuit, a TVG circuit, a detection circuit, a front and rear edge detection circuit, an algae extraction gate circuit, an algae output circuit, and an arithmetic circuit. Here, the transmission circuit outputs a transmission pulse signal, and the transmitter / receiver receives the transmission pulse signal, transmits an ultrasonic pulse toward the seabed, receives a reflected wave from the sea, and outputs a received signal. The amplifier circuit amplifies the received signal, and the TVG circuit corrects the output signal of the amplifier circuit for propagation attenuation. The detection circuit performs envelope detection of the output signal of the TVG circuit, and the front and rear edge detection circuit detects the leading and trailing edges of the various signals output by the detection circuit. The algae extraction gate circuit detects a seabed signal from the various signals output by the detection circuit, and forms and outputs an algae extraction gate signal of a predetermined time width based on the time position of the detected seabed signal. The algae output circuit forms an algae output gate signal, which is a signal indicating the leading edge and trailing edge output by the leading and trailing edge detection circuit, and has a passing time width between the time positions of the leading edge signal and trailing edge signal that exist within the time width of the algae extraction gate signal, and extracts the algae signal from the various signals output by the detection circuit using the algae output gate signal. The arithmetic circuit calculates the height and amount of algae from the time width and amplitude of the algae signal output by the algae output circuit. This separates the algae signal from the seabed signal, making it possible to automatically measure the height and amount of algae.

[0003] Also, Japanese Patent Laid-Open Publication No. 7-49375 (Patent Document 2) discloses an ultrasonic measuring device including a first means, a second means, an algae signal extraction means, and a calculation means. The first means transmits and receives ultrasonic pulses in a substantially vertically downward direction underwater, corrects the received first reflected signal by TVG, and corrects the propagation attenuation of the reflected signal from the algae that appears before the reflected signal from the seabed. The second means transmits and receives ultrasonic pulses in an oblique direction underwater at a predetermined depression angle in order to increase the level difference between the reflected signal level from the seabed and the reflected signal level from the algae, and obtains the time range of the reflected signal from the seabed by setting a predetermined threshold level for the received second reflected signal. The algae signal extraction means extracts only the reflected signal from the algae from the first reflected signal by utilizing the time range of the reflected signal from the seabed obtained by the second means from the first reflected signal corrected by the first means. The calculation means calculates the height of the algae to be measured from the time length of the reflected signal from the algae extracted by the algae signal extraction means, and calculates the density of the algae from the level of the reflected signal. This makes it possible to automatically measure the height and density of the algae that have settled on the seabed from a remote location, such as on a ship. In addition, JP-A-7-49376 (Patent Document 3) discloses a technology similar to that described in Patent Document 2.

[0004] In addition, Japanese Patent Laid-Open Publication No. 8-271629 (Patent Document 4) discloses an ultrasonic algae measurement device that transmits and receives ultrasonic waves to the sea / lake bottom and outputs a reflected image of algae growing on the sea / lake bottom. The device focuses on the fact that the reflected signal level is in the order of algae stems < algae leaves < sea / lake bottom, and that the algae stems, which have the weakest reflected signal level, are located in the middle. The device expands the reflected signal level difference and then sets the level below the reflected signal level of the algae leaves to 0. The device outputs a reflected image by forming a 0-level separation zone between the algae and the sea / lake bottom in the reflected image from the sea / lake bottom where the algae grow thick. This makes it possible to clearly distinguish between algae and the sea / lake bottom, which was previously difficult to distinguish, by displaying them separately in two layers, and it is said that ultrasonic surveys and measurements of seaweed beds can be performed accurately.

[0005] Also, JP 2013-252096 A (Patent Document 5) discloses a method for measuring the distribution of seaweed beds. Here, this method determines a first seaweed bed candidate area based on the dominance of the g component intensity of pixels in an aerial color image of the water area to be measured, determines a second seaweed bed candidate area based on changes in the measured water depth z of an acoustic bathymetry performed on the water area to be measured, and compares the first seaweed bed candidate area with the second seaweed bed candidate area to estimate the area where the two coincide as the seaweed bed area. This makes it possible to measure the distribution of seaweed bed areas simply and accurately.

[0006] In addition, JP 2019-024377 A (Patent Document 6) discloses a method for acquiring the distribution of seaweed beds by type. Here, in this method, the depth measurement value and the reflection intensity of ultrasonic waves measured together with the position information by a sonar system in a surveyed water area including seaweed beds are positionally associated with each section obtained by dividing the surveyed water area into a plurality of sections. In addition, in this method, for each section, a representative value of the scattering of the depth measurement value, a representative value of the reflection intensity, and the convexity of the section calculated from the depth measurement value are acquired, and the algae species and bottom sediment are statistically distinguished for each section using one or more of the representative value of the scattering of the depth measurement value, the representative value of the reflection intensity, and the convexity. In addition, this method integrates the discrimination results of each section to acquire the distribution of seaweed beds by type in the surveyed water area. As a result, it is said that it is possible to acquire the types of seaweed beds, their distribution, and the biomass distribution in a wide range of water areas with high spatial resolution.

[0007] In addition, JP 2024-071116 A (Patent Document 7) discloses a CO2 absorption evaluation system including a camera, a LiDAR (Light Detection And Ranging), a mobile body, and a CO2 absorption evaluation device. The mobile body is equipped with a camera and a LiDAR and is configured to be movable underwater. The CO2 absorption evaluation device includes a measurement unit and a calculation unit. The measurement unit measures the front area of ​​each seaweed in the seaweed bed from an image taken underwater by the camera, and measures the depth of each seaweed from the result of scanning the water with the LiDAR. The calculation unit calculates the weight of each seaweed based on the measurement result by the measurement unit, and calculates the CO2 absorption amount by the seaweed in the seaweed bed based on the calculated weight of each seaweed and the number of seaweed in the seaweed bed. This makes it possible to evaluate the CO2 absorption amount by the seaweed in the seaweed bed to be evaluated with high accuracy.

[0008] In addition, JP 2024-125623 A (Patent Document 8) discloses a data processing device having an acquisition unit, a modeling unit, and an estimation unit. The acquisition unit acquires captured image data generated by capturing images of underwater seaweed from a direction different from above the seaweed using an underwater camera. The modeling unit models the shape of the seaweed, including the length of the seaweed in the water depth direction and the width of the seaweed, by performing image analysis on the captured image data. The estimation unit estimates the amount of carbon dioxide absorption by the seaweed based on the modeled shape. This is said to improve the accuracy of determining the amount of CO2 absorption by the seaweed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 6-281736 [Patent Document 2] Japanese Patent Application Publication No. 7-49375 [Patent Document 3] Japanese Patent Application Publication No. 7-49376 [Patent Document 4] Japanese Patent Application Publication No. 8-271629 [Patent Document 5] JP 2013-252096 A [Patent Document 6] JP 2019-024377 A [Patent Document 7] JP 2024-071116 A [Patent Document 8] JP 2024-125623 A Summary of the Invention [Problem to be solved by the invention]

[0010] Here, in order to accurately evaluate the amount of carbon dioxide stored in a seaweed bed, it is preferable to use the dry weight of the algae living in the seaweed bed. For example, the dry weight of the algae can be calculated by taking out the algae from the seaweed bed, actually drying the algae, and measuring the dry weight. However, such a method is not practical because it takes time and effort.

[0011] On the other hand, if it were possible to calculate the area and volume of algae in a seaweed bed using an ultrasonic transmitter / receiver, it would be possible to roughly estimate the dry weight of the algae.

[0012] Here, the technology described in Patent Documents 1-4 uses ultrasound to calculate the height and density of algae from the time length and reflection intensity of the reflected signal from the algae, but the ultrasound used is narrow-band and the transmission signal length is long, so there is a possibility that the seabed echo and the algae echo may overlap, and these technologies have a problem that they cannot properly calculate the area and volume of the algae. Also, the technology described in Patent Document 5 uses an aerial camera to detect the distribution of the algae bed, but there is a problem that the aerial camera cannot measure the volume and density of the algae. Also, the technology described in Patent Document 6 uses a narrow multi-beam sonar to measure the depth measurement value and the reflection intensity of the ultrasound to distinguish the type of algae and the bottom sediment, but there is a problem that the narrow multi-beam sonar is expensive and cannot be easily implemented. Furthermore, the technology described in Patent Document 7 uses a camera and LiDAR to measure the area, height, and number of plants of algae, but there is a problem that measurement may be difficult depending on the condition of the algae bed because light attenuation is strong underwater. The technology described in Patent Document 8 uses an underwater camera to measure the height and width of algae, but there is a problem in that the area and volume of algae cannot be measured using only an underwater camera.

[0013] Therefore, the present invention has been made to solve the above-mentioned problems, and has an object to provide a seaweed bed evaluation system and a seaweed bed evaluation method that can easily evaluate underwater seaweed beds by using inexpensive ultrasonic transmitters that are generally used for fish detection. [Means for solving the problem]

[0014] The seaweed bed evaluation system according to the present invention includes a position information acquisition unit, an echo intensity acquisition unit, an algae echo detection unit, a height estimation unit, an area calculation unit, and an algae amount estimation unit. Here, the position information acquisition unit acquires position information of a moving body traveling near the water surface. The echo intensity acquisition unit is provided on the bottom surface of the moving body, and acquires echo intensity, which indicates a change in ultrasonic intensity with respect to the depth from the water surface to the seabed, for each ultrasonic transmitter / receiver using a plurality of ultrasonic transmitter / receivers arranged in the width direction of the moving body. The algae echo detection unit detects algae echoes corresponding to algae on the seabed from the acquired echo intensity. The height estimation unit estimates the height of the algae based on the detected algae echo. The area calculation unit calculates the area of ​​the algae present in the width direction of the moving body in the position information of the moving body, based on the height of the algae estimated from the echo intensity of each ultrasonic transmitter / receiver and the detection positions of the moving body in the width direction by the plurality of ultrasonic transmitter / receivers. The algae amount estimation unit repeats the process from acquiring the position information of the moving body to calculating the area of ​​the algae in the position information of the moving body along the route of the moving body, and calculates the volume of algae present between each piece of position information of the moving body's route based on the area of ​​algae for each piece of position information of the moving body's route and the distance traveled by the moving body, thereby estimating the amount of algae.

[0015] The method for evaluating a seaweed bed according to the present invention comprises a position information acquisition step, an echo intensity acquisition step, an algae echo detection step, a height estimation step, an area calculation step, and an algae amount estimation step. Each step of the method for evaluating a seaweed bed according to the present invention corresponds to each part of the system for evaluating a seaweed bed according to the present invention. Effect of the Invention

[0016] According to the present invention, it is possible to easily evaluate underwater seaweed beds using an inexpensive ultrasonic transmitter that is generally used for fish detection. [Brief description of the drawings]

[0017] [Figure 1] 1A is a schematic diagram showing an example of a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 1B is a diagram showing an example of a travel route of a moving body. [Diagram 2] FIG. 1 is a functional block diagram showing an example of a seaweed bed evaluation system according to an embodiment of the present invention. [Diagram 3] 1 is a flowchart showing an example of a method for evaluating a seaweed bed according to an embodiment of the present invention. [Figure 4] FIG. 4A shows an example of a moving body moving in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 4B shows an example of a case in which multiple ultrasonic transmitters and receivers transmit ultrasonic waves into the sea. [Diagram 5] FIG. 5A shows an example of echo intensity for first location information and second location information in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 5B shows an example of echo intensity with depth on the vertical axis and measurement time on the horizontal axis. [Figure 6] FIG. 11 is a diagram showing an example of a case where an algae echo is detected from echo intensity in the algae bed evaluation system according to the embodiment of the present invention. [Figure 7] FIG. 7A shows an example of estimating algae height from algae echoes in an algae bed evaluation system according to an embodiment of the present invention, FIG. 7B shows an example of calculating an echo integral value from an algae echo, and FIG. 7C shows an example of first related information when the feature value of the algae echo is the echo integral value, and second related information when the feature value of the algae echo is the algae height. [Figure 8] FIG. 8A shows an example of converting the height of algae inclined at a first angle and a second angle into the vertical direction in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 8B shows an example of converting the depth of the seabed inclined at a first angle and a second angle into the detection position of an ultrasonic transmitter / receiver to calculate the area of ​​the algae. [Figure 9] FIG. 9A shows an example of calculating the volume of algae between first location information and second location information in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 9B shows an example of calculating the amount of algae using the volume of algae and the density of algae between the first location information and second location information. [Figure 10]FIG. 10A shows an example of generating a seaweed bed between first location information and second location information in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 10B shows an example of generating a seaweed bed between each piece of location information on a travel route. [Figure 11] FIG. 1 is a diagram showing an example of a procedure from navigation survey to analysis of echo intensity, estimation of algae amount, and estimation of carbon dioxide storage amount in the seaweed bed evaluation system according to an embodiment of the present invention. [Figure 12] FIG. 12A shows an example of estimating the area of ​​algae by capturing underwater images with an underwater camera in a seaweed bed evaluation system according to an embodiment of the present invention, and FIG. 12B shows an example of generating a seaweed bed when the area of ​​algae is not estimated, and an example of generating a seaweed bed when the area of ​​algae is estimated. [Figure 13] FIG. 1 is a diagram showing an example of the procedure in a seaweed bed evaluation system according to an embodiment of the present invention, from navigation surveys to analysis of echo intensity, estimation of seaweed volume, estimation of carbon dioxide storage volume, taking underwater images with an underwater camera, and estimating the area of ​​seaweed. [Figure 14] FIG. 14A shows an example of placing sargassum in an aquarium, FIG. 14B shows an example of echo intensity in the aquarium when the number of sargassum plants is increased or decreased, and FIG. 14C shows an example of first related information showing the relationship between echo integral value and algae density, and second related information showing the relationship between algae height and algae density. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings to help the understanding of the present invention. Note that the following embodiment is an example of the present invention and is not intended to limit the technical scope of the present invention.

[0019] As shown in FIG. 1A, the seaweed bed evaluation system 1 according to an embodiment of the present invention includes a moving body 10, a GPS antenna 20, a plurality of ultrasonic transmitters / receivers 30, an underwater camera 40, a control unit 50, and a communication antenna 60.

[0020] Here, the moving body 10 can travel on the sea O according to the instructions of a user (a measurer, a manager, etc.). Here, the moving body 10 is not particularly limited, but examples thereof include a ship, a surface drone, an underwater drone, and the like.

[0021] Furthermore, a GPS antenna 20 is attached to the mobile body 10 and acquires from GPS satellites position information of the mobile body 10. The position information is position information in a geographic coordinate system, and may include, for example, longitude and latitude.

[0022] The ultrasonic transmitter / receiver 30 is provided on the bottom surface of the moving body 10 and arranged in the width direction of the moving body 10. Here, for example, the ultrasonic transmitter / receiver 30 includes a transmitting element (ultrasonic transducer) that transmits ultrasonic waves and a receiving element (ultrasonic transducer) that receives the reflected waves. The ultrasonic transmitter / receiver 30 transmits ultrasonic waves into the sea O and receives echoes from the seaweed 70 and the seabed 80.

[0023] Here, the arrangement of the ultrasonic transmitters and receivers 30 is not particularly limited, but examples include an arrangement in the shape of a fan extending downward from near the center of the width of the moving body 10, or an arrangement along the width of the moving body 10. The area in which the ultrasonic transmitters and receivers 30 transmit and receive ultrasonic waves extends along the width of the moving body 10, and forms a predetermined detection area D.

[0024] 1A, five ultrasonic transmitters / receivers 30 are arranged evenly in a fan shape along the width direction of the moving body 10. Each ultrasonic transmitter / receiver 30 transmits ultrasonic waves from above downward at the bottom surface of the moving body 10, and receives ultrasonic waves reflected from below upward. Identification information such as ch (channel) is set for each of the ultrasonic transmitters / receivers 30.

[0025] Furthermore, the ultrasonic waves may be, for example, a cone beam that spreads in a cone shape with a directional angle of 5 degrees. Here, the cone shape refers to the case where the shape of the transducer of the ultrasonic transmitter / receiver 30 is circular, and the shape of the transducer is a square pyramid when the shape of the transducer is square. Furthermore, the ultrasonic waves may be, for example, a fan beam. The frequency of the ultrasonic waves may be, for example, 240 kHz or 480 kHz.

[0026] The underwater camera 40 is provided on the bottom surface of the moving body 10. Here, the underwater camera 40 is a water-resistant camera, specifically, a camera for underwater photography in which a photographing element and the like are housed in a waterproof sealed container. The underwater camera 40 can photograph a detection area D in the width direction of the moving body 10 by the multiple ultrasonic transmitter-receivers 30, and the photographing area of ​​the underwater camera 40 constitutes a photographing area C included in the detection area D, for example, as shown in FIG. 1A. The arrangement of the underwater camera 40 is not particularly limited, but examples include an arrangement in which the underwater camera 40 is arranged near the front and rear or near the left and right of a specific ultrasonic transmitter-receiver 30 arranged in the center among the multiple ultrasonic transmitter-receivers 30 in the moving body 10.

[0027] The control unit 50 also controls each component constituting the seaweed bed evaluation system 1, and executes processes related to the operation of the seaweed bed evaluation system 1. There is no particular limitation on the configuration of the control unit 50, but for example, the control unit 50 is composed of a CPU, a dedicated circuit, etc. The control unit 50 also has a built-in CPU, ROM, RAM, etc. (not shown), and the CPU uses, for example, the RAM as a working area and executes programs stored in the ROM, etc. The CPU also executes programs to realize the functions of each component described below.

[0028] The communication antenna 60 is attached to the mobile body 10 and performs wireless communication with the outside, such as a ship or a control tower. Here, the communication antenna 60 can receive instructions and commands from the outside in the mobile body 10 and reflect them in the control unit 50. Also, a user who gets on the mobile body 10 can use the control unit 50 to transmit instructions and commands to the outside via the communication antenna 60. Here, the communication standard of the communication antenna 60 is not particularly limited, and examples thereof include 3G, 4G, 5G, 3GPP (registered trademark: 3rd Generation Partnership Project), 5GPP (5th Generation Partnership Project), LTE (Long Term Evolution), WIMAX (World Interoperability for Microwave Access), Wi-Fi, Internet, LAN (Local Area Network), Wireless LAN, WAN (Wide Area Network), and the like.

[0029] Now, as shown in FIG. 1B, the mobile body 10 travels in the shallow sea O on a beach B (land) and estimates the amount of seaweed in the sea O. Here, the user sets a predetermined route A (path) in the sea O using a map of the beach B where the amount of seaweed is to be estimated. This route A is set by the user in an accordion-like shape, for example, taking into consideration the detection areas D of the multiple ultrasonic transmitters / receivers 30 so that the multiple ultrasonic transmitters / receivers 30 mounted on the mobile body 10 can thoroughly detect the seaweed in the sea O. In other words, it is preferable that the route A is set so that the detection areas D for each position do not overlap. Also, the mobile body 10 travels along the route A by the user's operation or an external operation. For example, if the mobile body 10 is a ship, the user boards the ship and steers the ship to make the ship travel along the route A. Furthermore, for example, when the moving body 10 is a surface drone or an underwater drone, the user can create a route A based on position information such as a GPS in advance, and the moving body 10 can automatically travel based on the created route A. Furthermore, the surface drone or underwater drone can also travel based on the operation of a user on land by wirelessly communicating with the user using the communication antenna 60.

[0030] Next, the configuration and execution procedure according to the embodiment of the present invention will be described with reference to Fig. 2 to Fig. 13. First, a user gets on the moving body 10 and steers the moving body 10 to move to a measurement start point AS of a route A on the sea O, for example, as shown in Fig. 4A. This route A is set in advance by the user, as described above.

[0031] Next, the user starts up the seaweed bed evaluation system 1 mounted on the mobile body 10 (FIG. 3: S101). There is no particular limitation on the method for starting up the seaweed bed evaluation system 1, but for example, the user turns on the power to each component (the multiple ultrasonic transmitter / receivers 30, the underwater camera 40, and the control unit 50) required for processing by the seaweed bed evaluation system 1, and power supply to each component begins.

[0032] Now, when the seaweed bed evaluation system 1 is started up, it becomes possible for the multiple ultrasonic transmitters and receivers 30 to transmit and receive ultrasonic waves. Next, when the user inputs the start key into the control unit 50 of the seaweed bed evaluation system 1, the control unit 50 starts processing, and the position information acquisition unit 101 of the control unit 50 acquires the position information of the moving body 10 (Figure 3: S102).

[0033] Here, there is no particular limitation on the method of acquisition by the position information acquisition unit 101, but for example, the position information acquisition unit 101 acquires current position information P1 (e.g., first position information) (x1, y1) of the moving object 10 using the GPS antenna 20. Here, the acquired position information P1 is expressed, for example, as two-dimensional coordinate values ​​in a geographic coordinate system. In addition to acquiring the position information P1, the position information acquisition unit 101 may also acquire the current time t1 (e.g., first time) at which the position information P1 was acquired using a predetermined timer (e.g., a clock circuit).

[0034] Now, after the position information acquisition unit 101 acquires the position information P1, the echo intensity acquisition unit 102 of the control unit 50 then uses multiple ultrasonic transmitter / receivers 30 to acquire, for each ultrasonic transmitter / receiver 30, the echo intensity, which indicates the change in intensity of ultrasonic waves (echoes) with respect to the depth from the water surface to the seabed (Figure 3: S103).

[0035] Here, there is no particular limitation on the acquisition method of the echo intensity acquisition unit 102, but for example, as shown in Fig. 4B, the echo intensity acquisition unit 102 transmits ultrasonic waves S toward the sea from each ultrasonic transmitter / receiver 30 at the same time. The transmitted ultrasonic waves S are then incident on fish F, seaweed 70, the seabed 80, etc. present in the sea O, and are reflected. Furthermore, the echo intensity acquisition unit 102 receives the reflected ultrasonic waves S using the multiple ultrasonic transmitters / receivers 30, and acquires the reflection intensity of the ultrasonic waves S as the echo intensity.

[0036] Here, for example, as shown in FIG. 4B, when the five ultrasonic transmitters / receivers 30 are set from 1ch to 5ch from the right to the left of the moving body 10, the echo intensity acquisition unit 102 acquires the echo intensity for each channel, such as the echo intensity of 1ch, the echo intensity of 2ch, the echo intensity of 3ch, the echo intensity of 4ch, and the echo intensity of 5ch. In addition, since the five ultrasonic transmitters / receivers 30 are arranged in a fan shape from near the center of the width direction dimension of the moving body 10 toward the bottom, the central ultrasonic transmitter / receiver 30 (3ch) transmits ultrasonic waves S vertically from above to below, the second and fourth ultrasonic transmitters / receivers 30 (2ch, 4ch) from the right transmit ultrasonic waves S inclined from above to below at a first angle θ1, and the first and fifth ultrasonic transmitters / receivers 30 (1ch, 5ch) from the right transmit ultrasonic waves S inclined from above to below at a second angle θ2. The first angle θ1 and the second angle θ2 are then used to calculate the area of ​​the algae 70.

[0037] In the above description, the echo intensity acquisition unit 102 transmits ultrasonic waves S from each ultrasonic transmitter / receiver 30 simultaneously, but this is not limited to the above. For example, the echo intensity acquisition unit 102 may transmit ultrasonic waves S from each ultrasonic transmitter / receiver 30 one by one in a predetermined order.

[0038] Now, when the echo intensity acquisition unit 102 acquires the echo intensity, for example, this echo intensity is represented as a graph of echo intensity with the vertical axis representing echo intensity (10^4) and the horizontal axis representing depth (m) for the first position information P1 (x1, y1) and the first time t1 for a specific ultrasonic transmitter / receiver 30 (e.g., 1ch), as shown in FIG. 5A.

[0039] Then, for example, the moving body 10 travels further, and the position information acquisition unit 101 acquires position information P2 (e.g., second position information) at the next time point (Figure 3: S102), and the echo intensity acquisition unit 102 acquires echo intensity using a specific ultrasonic transmitter / receiver 30 (1ch) (Figure 3: S103), and this echo intensity becomes a graph of the second position information P2 (x2, y2) and echo intensity against the second time t2 at the specific ultrasonic transmitter / receiver 30 (1ch), as shown in Figure 5A.

[0040] In this way, when the echo intensity is sequentially acquired for each piece of position information of the moving body 10 in a specific ultrasonic transmitter / receiver 30 (1ch), it is possible to obtain the echo intensity for each time, with the vertical axis representing depth (m) and the horizontal axis representing a specific time (measurement time) (or specific position information), as shown in Fig. 5B. This echo intensity for each time can be acquired for each ultrasonic transmitter / receiver 30, and by analyzing this echo intensity for each time, it is possible to detect, for example, an echo of algae (algae echo).

[0041] Once the echo intensity acquisition unit 102 has acquired the echo intensity, the algae echo detection unit 103 of the control unit 50 then detects echoes of the algae 70 corresponding to the algae 70 on the seabed 80 from the acquired echo intensity (FIG. 3: S104).

[0042] Here, there is no particular limitation on the detection method of the algae echo detection unit 103, but as shown in Figure 6, for example, in a specific ultrasonic transmitter / receiver 30 (1ch), in the echo intensity for the first position information P1 (x1, y1) and the first time t1, at a shallow depth, there is a sharp peak P1, and at a deep depth, there is a peak P2 that combines with multiple peaks to form a gentler overall peak P2.

[0043] Here, for example, at a shallow depth, a sharp peak P1 corresponds to an ultrasonic wave from an object approaching a specific ultrasonic transmitter / receiver 30, and can usually be assumed to be a fish peak. On the other hand, at a deep depth, a gentle peak P2 corresponds to an ultrasonic wave from an object distant from the specific ultrasonic transmitter / receiver 30, and can usually be assumed to be a peak of, for example, algae 70 growing from the seabed 80. Therefore, the algae echo detection unit 103 detects the peak P2 that exists in a depth range deeper than a predetermined threshold value zd corresponding to the specific depth as an algae echo. Here, the predetermined threshold value zd is preferably set to, for example, a depth at which it is estimated that algae 70 grows from the seabed 80.

[0044] In the above description, the algae echo detection unit 103 detects the peak P2 in a predetermined depth range as an algae echo, but this is not limiting. For example, since a fish peak is a sharp peak and an algae peak is a gentle peak, the algae echo detection unit 103 may detect a gentle peak as an algae echo based on the shape of the peak in the echo intensity. Here, the algae echo detection unit 103 may specify the shape of the peak by, for example, calculating the concentration of the peak. The concentration of the peak is defined as the numerator of the echo intensity of the peak at a specific depth and the denominator of the sum of the echo intensities of the peaks located a predetermined distance (m) before and after the specific depth. Here, if the concentration of the peak is calculated as being sharp with respect to the distance (m) of 0, this means that the peak is sharp, and the peak can be detected as a fish peak. If the concentration of the peak is calculated as being gentle with respect to the distance (m) of 0, this means that the peak is gentle, and the peak can be detected as an algae echo. In this way, it is possible to detect only the algae echo caused by the algae 70 from the echo intensity.

[0045] Now, when the algae echo detection section 103 detects an echo of the algae, next, the height estimation section 104 of the control section 50 estimates the height h (m) of the algae 70 based on the detected algae echo (FIG. 3: S105).

[0046] Here, there is no particular limitation on the estimation method of the height estimation unit 104, but for example, as shown in Fig. 7A, the height estimation unit 104 calculates the start depth zs (m) and end depth ze (m) for peak P2 of the detected algae echo, and estimates the subtraction value obtained by subtracting the calculated start depth zs (m) from the calculated end depth ze (m) as the algae height h1 (m). This makes it possible to easily estimate the algae height h1 (m).

[0047] Here, the height estimation unit 104 may use the algae echo to estimate the height h (m) of the algae 70 and the density d (g / m3) of the algae 70. Specifically, the height estimation unit 104 estimates the height h (m) of the algae 70 based on the algae echo, calculates a feature amount α of the algae echo, and estimates the algae density d (g / m3) using pre-registered association information that associates the feature amount α of the algae echo with the algae density d (g / m3).

[0048] For example, as shown in Fig. 7B, the height estimation unit 104 first estimates the height h1 (m) of the algae 70 from the peak P2 of the detected algae echo. Next, the height estimation unit 104 calculates an echo integral value I1 obtained by integrating the intensity of the algae echo with respect to the depth for the peak P2 of the algae echo as a feature value α. Then, the height estimation unit 104 refers to first related information 700 stored in advance in a predetermined memory.

[0049] Here, the echo integral value I and the density d (g / m3) of the algae are stored in association with each other in the first association information 700, and as shown in Fig. 7C, the first association information 700 is expressed as a graph with the echo integral value I on the vertical axis and the density d (g / m3) of the algae 70 on the horizontal axis. This means that there is a certain correlation between the echo integral value I and the density d (g / m3) of the algae 70.

[0050] Therefore, the height estimation unit 104 compares the echo integral value I1 corresponding to the feature amount α of the algae echo with the echo integral value I of the first related information 700, identifies the density d1 (g / m3) of the algae corresponding to the compared echo integral value I of the first related information 700, and estimates the identified density d1 (g / m3) of the algae 70. This makes it possible to easily estimate the density d1 (g / m3) of the algae 70 from the echo integral value I. Here, by estimating the height h (m) of the algae 70 and the density d (g / m3) of the algae 70, it becomes possible to more specifically calculate the amount of algae from the area and volume of the algae 70.

[0051] In the above, the density d1 (g / m3) of the algae is estimated using the echo integral value I as the feature quantity α of the algae echo. However, this is not limited to the above, and for example, the density d (g / m3) of the algae may be estimated using the height h1 (m) of the algae echo as the feature quantity α of the algae echo.

[0052] For example, the height estimation unit 104 estimates the height h1 (m) of the algae for the peak P2 of the detected algae echo in the same manner as described above. Next, the height estimation unit 104 uses the height h1 (m) of the algae to refer to the second related information 701 stored in advance in a predetermined memory.

[0053] Here, the second association information 701 stores the algae height h (m) and the algae density d (g / m3) in association with each other, and as shown in Fig. 7C, the second association information 701 is expressed as a graph with the algae height h (m) on the vertical axis and the algae density d (g / m3) on the horizontal axis. This means that there is a certain correlation between the algae height h (m) and the algae density d (g / m3).

[0054] Therefore, the height estimation unit 104 compares the estimated algae height h1 (m) with the algae height h (m) in the second related information 701, identifies the algae density d2 (g / m3) corresponding to the compared algae height h (m) in the second related information 701, and estimates the identified algae density d2 (g / m3). This makes it possible to easily estimate the algae density d2 (g / m3) from the algae height h (m). In this case, since no predetermined calculation process is required, as with the echo integral value I, it may be possible to more easily estimate the algae density d2 (g / m3).

[0055] Once the height estimation unit 104 has completed the estimation, the area calculation unit 105 of the control unit 50 calculates the area s (m2) of the algae 70 present in the width direction of the moving body 10 at the position information P1 (x1, y1) of the moving body 10 based on the height h (m) of the algae estimated from the echo intensity of each ultrasonic transmitter / receiver 30 and the detection positions D in the width direction of the moving body by the multiple ultrasonic transmitters / receivers 30 (Figure 3: S106).

[0056] Here, there is no particular limitation on the calculation method of the area calculation unit 105. For example, as shown in Fig. 8A, the height h (m) of the algae 70 present directly below the central ultrasonic transmitter / receiver 30 (3ch) corresponds to the height h (m) of the algae estimated from the algae echo of the central ultrasonic transmitter / receiver 30 (3ch). Here, the height ha (m) of the algae estimated from the algae echo of the second and fourth ultrasonic transmitter / receivers 30 (2ch, 4ch) from the right corresponds to the height ha (m) of the algae inclined from above to below at a first angle θ1, and the height hb (m) of the algae estimated from the algae echo of the first and fifth ultrasonic transmitter / receivers 30 (1ch, 5ch) from the right corresponds to the height hb (m) of the algae inclined from above to below at a second angle θ2.

[0057] Therefore, the area calculation unit 105 uses trigonometric functions to multiply the height ha (m) of the algae tilted at the first angle θ1 by cos θ1, and converts the result into the height hc (m) of the algae at the second and fourth ultrasonic transmitter / receivers 30 (2ch, 4ch).The area calculation unit 105 also uses trigonometric functions to multiply the height hb (m) of the algae tilted at the second angle θ2 by cos θ2, and converts the result into the height hd (m) of the algae at the first and fifth ultrasonic transmitter / receivers 30 (1ch, 5ch).

[0058] 8B, the depth L1 (m) of the seabed 80 of the central ultrasonic transmitter / receiver 30 (3ch) is calculated from the end depth ze (m) of the algae echo of the central ultrasonic transmitter / receiver 30 (3ch). Here, the depth La (m) of the seabed 80 of the second and fourth ultrasonic transmitter / receivers 30 (2ch, 4ch) from the right is calculated from the end depth ze (m) of the algae echo tilted from above to below at a first angle θ1, and the depth Lb (m) of the seabed 80 of the first and fifth ultrasonic transmitter / receivers 30 (1ch, 5ch) from the right is calculated from the end depth ze (m) of the algae echo tilted from above to below at a second angle θ2.

[0059] Then, the area calculation unit 105 uses trigonometric functions to multiply the depth La(m) of the seabed 80 inclined at the first angle θ1 by sin θ1, and converts the multiplied value into the detection position Dc(m) of the second and fourth ultrasonic transmitter / receivers 30 (2ch, 4ch) moved in the width direction of the moving body 10 from the positions of the second and fourth ultrasonic transmitter / receivers 30 (2ch, 4ch). Also, the area calculation unit 105 uses trigonometric functions to multiply the depth Lb(m) of the seabed 80 inclined at the second angle θ2 by sin θ2, and converts the multiplied value into the detection position Dd(m) of the first and fifth ultrasonic transmitter / receivers 30 (1ch, 5ch) moved in the width direction of the moving body 10 from the positions of the first and fifth ultrasonic transmitter / receivers 30 (1ch, 5ch).

[0060] Here, the detection position Dc(m) of the second and fourth ultrasonic transmitter / receiver 30 (2ch, 4ch) and the detection position Dd(m) of the first and fifth ultrasonic transmitter / receiver 30 (1ch, 5ch) can be roughly estimated as the detection position moved in the width direction of the moving body 10 from the position of the central ultrasonic transmitter / receiver 30 (3ch).

[0061] Therefore, the area calculation unit 105 regards the heights h1 (m), hc (m), and hd (m) of the algae 70 from the first to fifth ultrasonic transmitter / receivers 30 (1ch to 5ch) as the upper and lower sides of a trapezoid, and regards the distance between the detection positions Dc (m), Dd (m) of the first to fifth ultrasonic transmitter / receivers 30 (1ch to 5ch) as the height of the trapezoid, and can calculate the area s (m2) of the algae 70 as (hd+hc)*(Dd-Dc) / 2+(hc+h1)*Dc / 2+(hd+hc)*(Dd-Dc) / 2+(hc+h1)*Dc / 2.

[0062] In the above, the height of the seaweed 70 tilted at the first angle θ1 and the second angle θ2 and the depth of the seabed are converted into the desired height and detection position of the seaweed 70 using trigonometric functions, but this is not limited to the above and the conversion may be performed using, for example, a specified interpolation method.

[0063] Also, the case where multiple ultrasonic transmitters / receivers 30 are arranged in a fan shape with respect to the moving body 10 has been described, but this is not limiting, and even if multiple ultrasonic transmitters / receivers 30 are arranged along the width direction of the moving body 10, the area s (m2) of the algae 70 can be calculated by calculating the height and detection position of the algae 70 at each ultrasonic transmitter / receiver 30. In other words, the area s (m2) of the algae 70 can be calculated from the relative positions of the ultrasonic transmitters / receivers 30 and the height of the algae 70.

[0064] Now, when the area calculation unit 105 completes the calculation, the algae amount estimation unit 106 of the control unit 50 next judges whether or not the traveling of the moving body 10 has been completed (FIG. 3: S107). Here, since the first position information P1(x1, y1) of the traveling route A is still the first position information, the algae amount estimation unit 106 judges that the traveling of the moving body 10 has not been completed (FIG. 3: S107 NO). Then, the algae amount estimation unit 106 returns to S102 and repeats the process from obtaining the position information P of the moving body 10 (FIG. 3: S102) to calculating the area s of the algae 70 in the position information P of the moving body 10 (FIG. 3: S106) on the traveling route A of the moving body 10 (FIG. 3: S107).

[0065] On the other hand, when the moving body 10 is operated by the user to move to the measurement completion point AE on the traveling route A, the area calculation unit 105 completes the calculation, and the algae amount estimation unit 106 determines whether the traveling of the moving body 10 has been completed (Figure 3: S107).

[0066] Here, since the moving body 10 has already moved to the measurement completion point AE on the traveling route A, the algae mass estimation unit 106 determines that the traveling of the moving body 10 is complete (FIG. 3: S107 YES). This completes the calculation of the area s of the algae 70 on the traveling route A. Note that the completion of the traveling of the moving body 10 is not limited to this. For example, when the user inputs an end key to the control unit 50 when the user thinks that the traveling of the moving body 10 is complete or wants to stop evaluating the seaweed bed, the algae mass estimation unit 106 may determine that the traveling of the moving body 10 is complete upon receiving the input of the end key (FIG. 3: S107 YES).

[0067] The algae amount estimation unit 106 then calculates the volume v (m3) of the algae 70 present between each piece of position information P on the course A of the moving body 10 based on the area s (m2) of the algae 70 for each piece of position information P on the course A of the moving body 10 and the travel distance p (m) of the moving body 10, and estimates the algae amount m (g) (Figure 3: S108).

[0068] Here, the estimation method of the algae amount estimation unit 106 is not particularly limited, but for example, when the height h (m) of the algae 70 is estimated, it is as follows: That is, as shown in Fig. 9A, a first area s1 (m2) of the algae 70 is calculated from the first position information P1 (x1, y1), and a second area s2 (m2) of the algae 70 is calculated from the second position information P2 (x2, y2).

[0069] First, the algae amount estimation unit 106 calculates the distance p (m) between the second position information P2 (x2, y2) and the first position information P1 (x1, y1) as the movement distance from the first position information P1 (x1, y1) to the second position information P2 (x2, y2). Next, the algae amount estimation unit 106 multiplies the calculated movement distance p (m) by the first area s1 (m2) of the algae 70 and the second area s2 (m2) of the algae 70, respectively, and calculates the multiplied value as the volume v1 (m3) of the algae 70 existing between the first position information P1 (x1, y1) and the second position information P2 (x2, y2).

[0070] The algae amount estimation unit 106 then uses the density d (g / m3) of common algae preregistered in a specified memory to multiply the calculated volume v1 (m3) of the algae 70 by the density (g / m3) of the algae 70 to calculate the multiplied value as the amount m1 (g) of algae present between the first position information P1 (x1, y1) and the second position information P2 (x2, y2). This makes it possible to easily estimate the amount of algae (g) on ​​the specified traveling route A.

[0071] Furthermore, the algae amount estimation unit 106 repeats the above-mentioned process for each position information P on the traveling route A to calculate the volume v (m3) of the algae 70 present at the intervals for each position information P, and estimates the algae amount m (g) using the volume v (m3) of the algae 70 and the density d (g / m3) of the algae 70, thereby making it possible to easily estimate the algae amount m (g) on ​​the traveling route A.

[0072] In particular, the present invention does not require expensive ultrasonic transmitters such as narrow-beam and multi-beam sonar, but instead uses inexpensive ultrasonic transmitters used in general fish detection, and by utilizing related information and appropriately analyzing echo intensity, it is possible to easily evaluate underwater seaweed beds.

[0073] Here, in the above, the amount of algae (g) was estimated using a general algae density d (g / m3), but this is not limited to the above. If the height h (m) of the algae 70 and the density d (g / m3) of the algae 70 are estimated using an algae echo, a more specific amount of algae (g) can be estimated.

[0074] Specifically, as shown in FIG. 9B, in the first position information P1 (x1, y1), a first area s1 (m2) of the algae 70 is calculated and the densities d11 (g / m3) to d15 (g / m3) of the algae 70 of the first to fifth ultrasonic transmitters / receivers 30 (1ch to 5ch) are estimated, and in the second position information P2 (x2, y2), a second area s2 (m2) of the algae 70 is calculated and the densities d21 (g / m3) to d25 (g / m3) of the algae 70 of the first to fifth ultrasonic transmitters / receivers 30 (1ch to 5ch) are estimated.

[0075] That is, a different density d (g / m3) of the algae 70 is estimated for each ultrasonic transmitter / receiver 30. In Fig. 9B, the greater the density d (g / m3) of the algae 70, the darker the color of the algae 70 is displayed. Since the degree of growth of the algae 70 varies depending on the location, this makes it possible to obtain a more realistic amount of algae.

[0076] Therefore, first, the algae amount estimation unit 106 calculates the travel distance from the first position information P1 (x1, y1) to the second position information P2 (x2, y2), and then multiplies the calculated travel distance p (m) by the first area s1 (m2) of the algae 70 and the second area s2 (m2) of the algae 70 to calculate the volume v1 (m3) of the algae 70 present from the first position information P1 (x1, y1) to the second position information P2 (x2, y2).

[0077] Then, the algae amount estimation unit 106 uses the densities d11 (g / m3) to d15 (g / m3) of the first to fifth algae 70 in the first position information P1 (x1, y1) and the densities d21 (g / m3) to d25 (g / m3) of the first to fifth algae 70 in the second position information P2 (x2, y2) to multiply the calculated volume v1 (m3) of the algae 70 by the density (g / m3) of the algae 70 to calculate the amount m1 (g) of algae present from the first position information P1 (x1, y1) to the second position information P2 (x2, y2).

[0078] Here, there is no particular limitation on how the density d (g / m3) of the algae 70 is used by the algae amount estimation unit 106. For example, the density d (g / m3) of the algae 70 may be simply calculated by averaging the densities d11 (g / m3) to d15 (g / m3) of the algae 70 in the first position information P1 (x1, y1) and the densities d21 (g / m3) to d25 (g / m3) of the algae 70 in the second position information P2 (x2, y2), estimating this average value as the density d (g / m3) of the algae 70 existing from the first position information P1 (x1, y1) to the second position information P2 (x2, y2), and multiplying this by the volume v1 (m3) of the algae 70. Alternatively, the density d (g / m3) of each algae 70 may be weighted using the height h (m) of the algae 70 used in calculating the area s (m2) of the algae 70, and the weighted density d (g / m3) of the algae 70 may be multiplied by the volume v1 (m3) of the algae 70. This allows the amount of algae (g) on ​​a given travel route A to be estimated with high accuracy.

[0079] Here, the estimated amount of algae m (g) is used to generate the algae bed MP as follows: When the algae amount estimation unit 106 completes the estimation, the algae bed generation unit 107 of the control unit 50 generates the algae bed MP including the traveling route A based on the traveling route A of the mobile body 10 and the amount of algae m (g / m3) between each piece of position information P of the traveling route A (FIG. 3: S109).

[0080] Here, the method of generation by the seaweed bed generation unit 107 is not particularly limited, but for example, as shown in FIG. 10A, the seaweed bed generation unit 107 prepares a map of the sea O of the beach B to be surveyed this time, and on that map, taking into consideration the detection size in the width direction of the moving body 10, identifies a section (e.g., a rectangular section) between the first position information P1 (x1, y1) and the second position information P2 (x2, y2), and assigns a color to the section according to the amount of seaweed m1. Then, as shown in FIG. 10B, the seaweed bed generation unit 107 generates a seaweed bed MP including the traveling route A by repeatedly identifying the section between each piece of position information P of the traveling route A and assigning a color to the section. This enables the user to visually grasp the distribution state of the seaweed 70.

[0081] Alternatively, the amount of carbon dioxide stored by the algae 70 can be calculated using the estimated algae mass m(g) as follows: When the algae mass estimation unit 106 completes the estimation, the storage amount calculation unit 108 of the control unit 50 calculates the amount of carbon dioxide stored by the algae 70 based on the algae mass m(g) between each piece of position information P on the traveling route A (FIG. 3: S110).

[0082] Here, the calculation method of the storage amount calculation unit 108 is not particularly limited, but for example, the storage amount calculation unit 108 calculates the total algae amount mt(g) by adding up all the algae amounts m(g) between each piece of position information P on the traveling route A, and calculates the dry weight mtd(g) of the entire algae from the total algae amount mt(g) using a predetermined conversion formula. Next, the storage amount calculation unit 108 calculates the amount of carbon dioxide estimated to be stored in the algae 70 from the calculated dry weight mtd(g) using a predetermined conversion formula. In this case, as shown in FIG. 11, the moving body 10 is caused to travel, and echo intensities from multiple ultrasonic transmitters / receivers 30 are acquired and analyzed, thereby estimating the algae amount m and generating the algae bed MP, and it becomes possible to numerically evaluate how much carbon dioxide is stored in the current algae bed.

[0083] As described above, a method for estimating the amount of algae m using multiple ultrasonic transmitters / receivers 30 has been explained. From here on, a method for evaluating a seaweed bed using an underwater camera 40 in addition to multiple ultrasonic transmitters / receivers 30 will be explained.

[0084] That is, in S102, when the position information acquisition unit 101 acquires position information P1 (e.g., first position information) (x1, y1) of the moving body 10, the echo intensity acquisition unit 102 uses multiple ultrasonic transmitters / receivers 30 to acquire the echo intensity for each ultrasonic transmitter / receiver 30 (Figure 3: S103), and in parallel with this, the image acquisition unit 201 of the control unit 50 uses the underwater camera 40 to acquire an underwater image including algae 70 present in the detection area D (Figure 3: S201).

[0085] Here, there is no particular limitation on the acquisition method of the image acquisition unit 201, but for example, when the position information acquisition unit 101 acquires position information P1 (or when the echo intensity acquisition unit 102 acquires echo intensity), the image acquisition unit 201 starts up the underwater camera 40 as shown in Fig. 12A to capture an image of the underwater scene including the algae 70, and acquires an underwater image 1200 including the algae 70. This makes it possible to acquire an underwater image 1200 in the detection area D where the ultrasonic wave S is applied by the ultrasonic transmitter / receiver 30.

[0086] Now, when the image acquisition section 201 completes acquisition, the algae image detection section 202 of the control section 50 next detects an algae image showing the algae 70 based on the acquired underwater image 1200 (FIG. 3: S202).

[0087] Here, there is no particular limitation on the detection method of the algae image detection unit 202, but for example, as shown in Fig. 12A, the algae image detection unit 202 searches for an algae image 1200a corresponding to the shape of the algae from the acquired underwater image 1200 and detects the algae image 1200a. Alternatively, the algae image detection unit 202 may search for an algae image 1200a having a color component of a pre-registered algae from the underwater image 1200 and detect the algae image 1200a. Furthermore, the algae image detection unit 202 may have a predetermined image machine learning unit learn algae images in advance, and detect the algae images by searching for algae images 1200a that are the same as or similar to the algae images learned by the image machine learning unit from the underwater image 1200.

[0088] Once the algae image detection unit 202 has completed detection, the algae region estimation unit 203 then estimates the region R1 of the algae 70 in the detection area D based on the detected algae image 1200a (FIG. 3: S203).

[0089] Here, there is no particular limitation on the estimation method used by the algae region estimation unit 203, but for example, as shown in FIG. 12A, the algae region estimation unit 203 identifies a boundary portion that indicates the boundary between the algae and the water in the detected algae image 1200a, and estimates a region R1 of the algae 70 in the detection area D by connecting together the identified boundary portions that are located furthest from the algae image 1200a. The region R1 of the algae 70 may also be estimated by roughly connecting together a plurality of boundary portions. Then, the estimated region R1 of the algae 70 is distinguished from, for example, a region R2 of the seabed 80.

[0090] Here, the seaweed region estimation unit 203 repeats estimation of the region R1 of the seaweed 70 for the underwater image 1200 acquired for each piece of position information P. As a result, the region R1 of the seaweed 70 is estimated in the sea O of the beach B that is the subject of this investigation, and the above-mentioned seaweed bed MP can be expressed in more detail. For example, as shown in FIG. 12B, when the region R1 of the seaweed 70 is not estimated, the seaweed bed MP is configured with a colored section of a predetermined shape, but when the region R1 of the seaweed 70 is estimated, the seaweed bed MP is configured with the region R1 of the seaweed 70 curved relative to the section. In other words, by using the underwater camera 40, the region R1 of the seaweed 70 in the detection area D of the multiple ultrasonic transmitter-receivers 30 can be specifically identified. This makes it possible to express the seaweed bed MP more accurately.

[0091] The algae region estimation unit 203 may also estimate the type of algae bed MP from the algae image 1200a. Algae beds are usually divided into eelgrass beds made up of eelgrass species, Sargassum beds made up of Sargassum species, Eisenia bicolor beds made up of Eisenia bicolor, kelp beds, wakame beds, etc. It is possible to identify the specific type of algae bed by identifying the types of algae that constitute these algae beds. Therefore, the algae region estimation unit 203 may have a predetermined image machine learning unit learn algae images that constitute the algae bed for each type of algae bed in advance, search for algae images that are the same as or similar to the algae images learned by the image machine learning unit from the algae image 1200a, and estimate the type of algae bed MP corresponding to the searched algae image. This makes it possible to express the algae bed MP more specifically.

[0092] In this way, in the present invention, as shown in Figure 13, by traveling a mobile body 10, it is possible to estimate the amount of algae m and the amount of stored carbon dioxide based on the echo intensity from multiple ultrasonic transmitters and receivers 30, and it is also possible to estimate the area R1 of algae 70 based on underwater images from an underwater camera 40, thereby generating a more accurate seaweed bed MP.

[0093] In the present invention, a simple experiment was carried out to estimate the amount of algae more specifically, and the results of the experiment are shown below.

[0094] First, as shown in FIG. 14A, a tank filled with water was prepared, and the algae Sargassum was placed in the tank, and the echo intensity in the tank was acquired by the ultrasonic transducer 30. At that time, the change in echo intensity was confirmed by increasing or decreasing the number of Sargassum in the tank. Here, an increase or decrease in the number of Sargassum corresponds to an increase or decrease in the density of the algae. As shown in FIG. 14B, it can be seen that the acquired echo intensity changed according to an increase or decrease in the number of Sargassum (an increase or decrease in the density of the algae). In addition, the algae echo was detected from the echo intensity, and the start depth and end depth of the peak of the algae echo were calculated, and the height of the algae was calculated. Since it corresponded to the length of the Sargassum in the tank, the height of the algae could be estimated from the algae echo.

[0095] Next, we tried to calculate the density of algae from the algae echo. Specifically, we detected algae echoes from the echo intensity for each number of sargassum, and calculated the algae echo integral value for each number of sargassum based on the detected algae echo. Then, we created a graph with the echo integral value on the vertical axis and the algae density corresponding to the number of sargassum on the horizontal axis. As a result, as shown in Figure 14C, it was found that there is a certain correlation between the algae echo integral value and the algae density.

[0096] Next, the length of the sargassum (height of the algae) was calculated based on the algae echo for each number of sargassum stalks, and a graph was created with the algae height corresponding to the length of the sargassum on the vertical axis and the algae density corresponding to the number of sargassum stalks on the horizontal axis. As a result, as shown in Figure 14C, it was found that there is a certain correlation between the algae height and the algae density.

[0097] In this way, it was possible to estimate the height of the algae from the algae echo. Furthermore, it was possible to estimate the density of the algae by using the echo integral value of the algae echo or the height of the algae as the feature value α of the algae echo. And, by using the above-mentioned experimental results, the present invention makes it possible to estimate the amount of algae, as well as to evaluate the associated algae bed and estimate the amount of carbon dioxide stored. It can be seen that these estimation results are extremely useful for marine development and global warming countermeasures. [Industrial Applicability]

[0098] As described above, the seaweed bed evaluation system and seaweed bed evaluation method of the present invention are extremely useful not only in the marine field but also in the field of global warming countermeasures, and are effective as a seaweed bed evaluation system and seaweed bed evaluation method that can easily evaluate underwater seaweed beds using inexpensive ultrasonic transmitters used in general fish finders. [Explanation of symbols]

[0099] 1. Seaweed Bed Evaluation System 10 Mobile 20 GPS antenna 30 Ultrasonic Transmitter 40 Camera 50 Control section 60 Communication Antenna 101 Location information acquisition unit 102 Echo intensity acquisition unit 103 Algae echo detector 104 Height Estimation Unit 105 Area calculation part 106 Algae amount estimation section 107 Seaweed bed generation part 108 Storage volume calculation unit 201 Image Acquisition Unit 202 Algae image detection unit 203 Algae area estimation department

Claims

1. a position information acquisition unit that acquires position information of a moving object traveling near the water surface; an echo intensity acquisition unit that is provided on the bottom surface of the moving body and acquires, for each ultrasonic transmitter / receiver, an echo intensity that indicates a change in intensity of ultrasonic waves with respect to a depth from the water surface to the seabed, using a plurality of ultrasonic transmitter / receivers arranged in a width direction of the moving body; an algae echo detection unit that detects an algae echo corresponding to the algae on the seabed from the acquired echo intensity; a height estimation unit that estimates the height of the algae based on the detected algae echo; an area calculation unit that calculates an area of ​​algae present in the width direction of the moving body in the position information of the moving body based on the height of the algae estimated from the echo intensity of each ultrasonic transmitter / receiver and the detection positions of the moving body in the width direction by the plurality of ultrasonic transmitters / receivers; an algae amount estimation unit that repeats the process from acquiring the position information of the moving body to calculating the area of ​​the algae in the position information of the moving body on the traveling route of the moving body, and calculates the volume of the algae present between each piece of position information of the traveling route of the moving body based on the area of ​​the algae for each piece of position information of the traveling route of the moving body and the moving distance of the moving body, thereby estimating the amount of algae; A seaweed bed evaluation system equipped with:

2. the height estimation unit estimates the height of the algae and estimates the density of the algae based on a feature of the algae echo and preregistered association information that associates the feature of the algae echo with the density of the algae; The algae amount estimation unit estimates the amount of algae based on an area of ​​algae for each piece of position information of the traveling route of the moving body, a travel distance of the moving body, and the estimated algae density. The seaweed bed evaluation system according to claim 1.

3. an image acquisition unit that is provided on a bottom surface of the moving body and that acquires an underwater image including algae present in a detection area by using an underwater camera that can capture an image of a detection area in a width direction of the moving body detected by the plurality of ultrasonic transmitters; an algae image detection unit that detects an algae image showing the algae based on the acquired image; an algae region estimation unit that estimates an algae region in the detection area based on the detected algae image; Equipped The seaweed bed evaluation system according to claim 1.

4. a position information acquiring step of acquiring position information of a moving object traveling near the water surface; an echo intensity acquisition step of acquiring, for each ultrasonic transmitter / receiver, an echo intensity indicating a change in ultrasonic intensity with respect to a depth from the water surface to the seabed, using a plurality of ultrasonic transmitter / receivers provided on the bottom surface of the moving body and arranged in a width direction of the moving body; an algae echo detection step of detecting an algae echo corresponding to the algae on the seabed from the acquired echo intensity; a height estimation step of estimating a height of the algae based on the detected algae echo; an area calculation step of calculating an area of ​​algae present in the width direction of the moving body in the position information of the moving body based on the height of the algae estimated from the echo intensity of each ultrasonic transmitter / receiver and the detection positions in the width direction of the moving body by the plurality of ultrasonic transmitters / receivers; an algae amount estimation process for repeating the process from acquiring the position information of the moving body to calculating the area of ​​the algae in the position information of the moving body on the traveling route of the moving body, and calculating the volume of the algae present between each piece of position information of the traveling route of the moving body based on the area of ​​the algae for each piece of position information of the traveling route of the moving body and the moving distance of the moving body, thereby estimating the amount of algae; The method for evaluating seaweed beds comprises:

Images