JP7518802B2 - Underwater observation system and underwater observation method - Google Patents

Description

The present invention relates to an underwater observation system and an underwater observation method.

Conventional techniques for observing ocean conditions include calculating the distribution of sea surface temperatures based on data observed by meteorological observation satellites, and collecting data observed by Argo floats via satellite in the Argo program.

Patent Document 1 describes a technology for remotely controlling multiple drones underwater from land via communications, in which drones located far from land communicate wirelessly via other drones (hopping).
Patent document 2 describes a technology in which multiple communication paths are prepared between a terminal and a base station underwater, and if the terminal does not receive a response from the base station over one communication path, it switches the communication path between the base stations to another communication path.

JP 2018-90017 A JP 2009-260756 A

Data collected by meteorological observation satellites cannot measure undersea conditions. Furthermore, the Argo floats in the Argo mission are spaced at intervals of approximately 300 km, making it difficult to make precise measurements of undersea conditions. Furthermore, Patent Documents 1 and 2 do not disclose how to make precise measurements of underwater conditions.

As shown in Figure 12, by placing multiple sensors on the sea surface or underwater at regular intervals D and measuring the water temperature and salinity at the same time, it is possible to measure the conditions under the sea precisely. Here, sensors placed on the sea surface can determine their own position using the Global Positioning System (GPS) and maintain a predetermined position. On the other hand, sensors placed underwater cannot determine their own position because they cannot use GPS. For this reason, as shown in Figure 13, sensors placed underwater cannot return to their predetermined position even if they are swept away by ocean currents, and the spacing between each sensor is no longer equal.

The present invention was made in consideration of these circumstances, and its purpose is to precisely measure underwater conditions using multiple sensor devices.

(1) One aspect of the present invention is an underwater observation system comprising a plurality of sensor devices capable of autonomously moving on and underwater, the sensor devices comprising a control unit, a sensor unit that measures a specific measurement item, a time information acquisition unit that acquires time information indicating the current time, a position information acquisition unit that acquires position information indicating its own current position, a surface communication unit that performs wireless communication with a base station, and an underwater communication unit that communicates with sensor devices disposed underwater, wherein at least three of the sensor devices are disposed on the water surface and a plurality of the sensor devices are disposed underwater, and in the water surface sensor devices that are the sensor devices disposed on the water surface, the control unit transmits water surface placement information including its own sensor identification information, the time information, and the position information to the sensor devices disposed underwater by the underwater communication unit, receives sensor measurement data transmitted from the sensor devices disposed underwater by the underwater communication unit, and transmits sensor measurement data received by the underwater communication unit to the sensor devices disposed underwater. This is an underwater observation system in which an underwater sensor device is a sensor device that is placed underwater and transmits measurement data to a specified data collection device via the water surface communication unit, the control unit receives water surface placement information transmitted from at least three of the water surface sensor devices via the underwater communication unit, and transmits sensor measurement data of specified measurement items measured by the sensor unit at a specified measurement timing to the water surface sensor device via the underwater communication unit, the position information acquisition unit calculates its own position based on the distance between the water surface sensor device based on the communication delay time between the water surface sensor device and the underwater communication unit, the water surface placement information received by the underwater communication unit, and the water depth measured by the sensor unit, and the control unit controls its own movement based on its own position calculated by the position information acquisition unit and the position of the water surface sensor device so that it has a specified positional relationship with the water surface sensor device.
(2) One aspect of the present invention is an underwater observation system as described above in (1 ), in which, when a sensor device in a first group consisting of a plurality of sensor devices arranged at a predetermined water depth becomes unable to communicate, a sensor device in a second group adjacent to the first group moves from the position of the second group toward the first group, and the groups are reorganized as a result of the movement .
(3) One aspect of the present invention is an underwater observation system of either (1) or (2) above, wherein the sensor device further includes a solar power generation unit that generates solar power, and in the underwater sensor device, the control unit controls the movement of the sensor device so that it rises to the surface after a certain amount of time has elapsed since it was placed underwater.
(4) One aspect of the present invention is an underwater observation system as described above in (3), in which, when a group consisting of a plurality of sensor devices arranged at a predetermined water depth rises to the water surface, other groups other than the group in question move to the original water depth of the group in question.
(5) One aspect of the present invention is an underwater observation system of any of (1) to (4) above, further comprising an autonomous underwater robot, and a sensor group consisting of a plurality of sensor devices arranged at a water depth shallower than the autonomous underwater robot, the sensor group moving in accordance with the movement of the autonomous underwater robot while taking underwater measurements.
(6) One aspect of the present invention is an underwater observation system of any of (1) to (5) above, in which, in the underwater sensor device, the control unit estimates a position to which the water surface sensor device will move after a certain time period based on water surface positioning information and speed information received from the water surface sensor device, calculates its own target position after a certain time period based on the estimated position of the water surface sensor device after the certain time period, estimates its own position to which it will move after a certain time period based on its own speed, and adjusts its own movement direction and speed so that its position after the certain time period becomes the target position.
(7) One aspect of the present invention is an underwater observation system of any of (1) to (6) above, in which at least one of a group consisting of a plurality of underwater sensor devices arranged at a predetermined water depth is connected to a water surface sensor device by an electrical cable and receives power from the water surface sensor device.
(8) One aspect of the present invention is an underwater observation system of any of (1) to (7) above, in which a group consisting of a plurality of underwater sensor devices arranged at a predetermined water depth is arranged in a plurality of layers at different water depths.
(9) One aspect of the present invention is an underwater observation system of any of (1) to (8) above, wherein the water surface sensor device collects location information indicating the location of the underwater sensor device from the underwater sensor device, the water surface sensor device transmits location information indicating its own location and location information indicating the location of the underwater sensor device to an operator terminal via the water surface communication unit, the water surface sensor device receives a target position of the water surface sensor device and a target distance between the underwater sensor device and a higher layer from the operator terminal via the water surface communication unit, the water surface sensor device autonomously moves to the target position, the water surface sensor device notifies the underwater sensor device of the target distance via the underwater communication unit, and the underwater sensor device autonomously moves so as to set the distance between itself and the higher layer to the target distance.

(10) One aspect of the present invention is an underwater observation method for an underwater observation system comprising a plurality of sensor devices capable of autonomously moving on and underwater, the sensor devices comprising a control unit, a sensor unit that measures specific measurement items, a time information acquisition unit that acquires time information indicating the current time, a position information acquisition unit that acquires position information indicating its own current position, a surface communication unit that performs wireless communication with a base station, and an underwater communication unit that communicates with sensor devices disposed underwater, wherein at least three of the sensor devices are disposed on the water surface, and a plurality of the sensor devices are disposed underwater, the control unit of the water surface sensor device that is the sensor device disposed on the water surface transmits water surface placement information including its own sensor identification information, the time information, and the position information to the sensor device disposed underwater via the underwater communication unit, the control unit of the underwater sensor device that is the sensor device disposed underwater receives the water surface placement information transmitted from the at least three water surface sensor devices via the underwater communication unit, and the position information acquisition unit of the underwater sensor device transmits the water surface placement information to the sensor device disposed underwater. The underwater observation method includes the steps of: calculating the position of the underwater sensor device based on the distance between the underwater sensor device and the water surface sensor device based on the communication delay time between the underwater communication unit and the water surface sensor device, the water surface arrangement information received by the underwater communication unit, and the water depth measured by the sensor unit; controlling the movement of the underwater sensor device so that the underwater sensor device and the water surface sensor device are in a predetermined positional relationship based on the position of the underwater sensor device calculated by the position information acquisition unit and the position of the water surface sensor device; transmitting sensor measurement data of a predetermined measurement item measured by the sensor unit at a predetermined measurement timing to the water surface sensor device by the underwater communication unit by the control unit of the underwater sensor device; receiving the sensor measurement data transmitted from the underwater sensor device by the underwater communication unit by the control unit of the water surface sensor device; and transmitting the sensor measurement data received by the underwater communication unit to a predetermined data collection device by the water surface communication unit by the control unit of the water surface sensor device.

The present invention has the advantage that underwater conditions can be precisely measured using multiple sensor devices.

1 is a block diagram showing an example of the configuration of an underwater observation system according to an embodiment. 1 is a block diagram showing an example of the configuration of a sensor device according to an embodiment; 1 is a flowchart illustrating an example of a procedure of an underwater observation method according to an embodiment. FIG. 1 is an explanatory diagram of an underwater positioning method according to an embodiment. FIG. 13 is a diagram showing an example of the configuration of water surface arrangement information according to an embodiment. 1 is an explanatory diagram of an example of a method for measuring a distance between a sea surface sensor device and an underwater sensor device according to an embodiment; 1 is an explanatory diagram of an example of a method for measuring a distance between a sea surface sensor device and an underwater sensor device according to an embodiment; FIG. 2 is a diagram illustrating a configuration example of dynamic measurement according to an embodiment. 1A to 1C are diagrams illustrating an example of a gap correction method according to an embodiment. FIG. 2 is a diagram illustrating an example of an arrangement of a sensor device according to an embodiment. FIG. 2 is a diagram illustrating an example of an arrangement of a sensor device according to an embodiment. FIG. 2 is a diagram illustrating an example of an arrangement of a sensor device according to an embodiment. FIG. 13 is a diagram illustrating an example of an abnormal state of the arrangement of sensor devices.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the surface of the ocean and underwater are used as examples of water surfaces and underwater areas, but the surface of water and underwater areas of lakes, artificial dams, pools, etc. may also be used.

Figure 1 is a block diagram showing an example of the configuration of an underwater observation system according to one embodiment. In the underwater observation system 1 shown in Figure 1, multiple sensor devices 3 (3-1, 3-2, 3-3, 3-4, 3-5, 3-6, 3-7, 3-8) are placed on the sea surface or underwater. When there is no particular need to distinguish between the sensor devices 3 (3-1, 3-2, 3-3, 3-4, 3-5, 3-6, 3-7, 3-8), they will be referred to as sensor devices 3. Furthermore, the sensor devices 3 may be referred to as sensors 3.

The sensor devices 3 are capable of autonomously moving on the sea surface and underwater. At least three sensor devices 3 (3-1, 3-2, 3-3) are placed on the sea surface. In addition, multiple sensor devices 3 (3-4, 3-5, 3-6, 3-7, 3-8) are placed underwater (below the sea surface).

Sensor devices (sea surface sensor devices) 3-1, 3-2, and 3-3 arranged on the sea surface constitute group X. Of sensor devices (subsea sensor devices) 3-4, 3-5, 3-6, 3-7, and 3-8 arranged underwater, subsea sensor devices 3-4 and 3-5 arranged at a certain first depth from the sea surface constitute group Y. Subsea sensor devices 3-6, 3-7, and 3-8 arranged at a certain second depth from the sea surface constitute group Z. The second depth is deeper than the first depth. The group to which it belongs and the arrangement are set in advance for each sensor device 3. For example, as shown in FIG. 12, the arrangement of each sensor device 3 is set in advance so that the sensor devices 3 are equally spaced at a certain interval D.

The base station BS is a base station (cellular base station) of the cellular network NW. When the sea level sensor devices 3-1, 3-2, and 3-3 are within the communication range of the base station BS, they connect to the base station BS via a wireless line 101 and communicate with the data collection device 5 via the cellular network NW. The data collection device 5 collects sensor measurement data measured by each sensor device 3 via the sea level sensor devices 3-1, 3-2, and 3-3.
In the present embodiment, a cellular network NW is used as an example of a wireless communication network, but is not limited thereto. A wireless LAN (Local Area Network), a LPWA (Low Power Wide Area Network), or the like may be used as the wireless communication network.

The sea level sensor devices 3-1, 3-2, and 3-3 receive GPS signals transmitted from GPS satellites 7 and obtain position information (latitude, longitude) indicating their current positions via GPS.

The sea surface sensor devices 3-1, 3-2, and 3-3 communicate underwater with the underwater sensor devices 3-4 and 3-5 belonging to group Y and the underwater sensor devices 3-6, 3-7, and 3-8 belonging to group Z. The underwater sensor devices 3-4 and 3-5 belonging to group Y communicate underwater with the underwater sensor devices 3-6, 3-7, and 3-8 belonging to group Z. Underwater communication is performed using sound waves.

Figure 2 is a block diagram showing an example of the configuration of a sensor device according to this embodiment. In Figure 2, the sensor device 3 includes a control unit 10, a sensor unit 11, a clock unit 12, a GPS unit 13, a surface communication unit 14, an underwater communication unit 15, a power supply unit 16, a solar power generation unit 17, and a propulsion unit 18.

The control unit 10 controls each part of the sensor device 3. The functions of the control unit 10 are realized when the control unit 10 includes computer hardware such as a CPU (Central Processing Unit) and memory, and the CPU executes a computer program stored in the memory. The control unit 10 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device.

The sensor unit 11 measures specific measurement items. For example, the sensor unit 11 measures water depth, water temperature, salinity, etc.

The clock unit 12 (time information acquisition unit) acquires time information indicating the current time. The GPS unit 13 (location information acquisition unit) acquires location information indicating the device's current location via GPS. In addition, the time information acquired by the GPS unit 13 via GPS is used to synchronize the time of the clock unit 12.

When the water surface communication unit 14 is within the communication range of the base station BS, it connects to the base station BS via a wireless line 101 and communicates with the data collection device 5 via the cellular network NW.

The underwater communication unit 15 communicates underwater with the underwater sensor device 3 placed underwater.

The power supply unit 16 supplies power to each component. The solar power generation unit 17 generates solar power. The battery of the power supply unit 16 is charged by the power generated by the solar power generation unit 17.

The propulsion unit 18 moves its own sensor device 3 according to movement instructions from the control unit 10.

Next, the underwater observation method according to this embodiment will be described with reference to FIG. 3. FIG. 3 is a flowchart showing an example of the procedure of the underwater observation method according to this embodiment.

(Step S1) Layout settings are performed for each sensor device 3. In this layout setting, the group to which each sensor device 3 belongs and the layout (water depth, latitude, longitude) of each sensor device 3 are set.

(Step S2) When the sensor device 3 is thrown into the sea, the control unit 10 of the sensor device 3 controls the propulsion unit 18 to move to the location set for the sensor device 3 (water depth, latitude, longitude: predetermined location). At this time, the sea level sensor devices 3-1, 3-2, and 3-3 of group X determine their current positions using the GPS unit 13 and move to the predetermined location. As a result, the sea level sensor devices 3-1, 3-2, and 3-3 move to the predetermined location.

On the other hand, the underwater sensor devices 3-4, 3-5, 3-6, 3-7, and 3-8 of groups Y and Z cannot determine their current positions using the GPS unit 13. For this reason, the underwater sensor devices 3-4, 3-5, 3-6, 3-7, and 3-8 of groups Y and Z determine their current positions based on water surface arrangement information and the like transmitted from the sea surface sensor devices 3-1, 3-2, and 3-3 of group X.

Now, referring to FIG. 4, a method for the underwater sensor device 3 to grasp its current position will be described. FIG. 4 is an explanatory diagram of the underwater position grasping method according to this embodiment. The sea surface sensor device 3 transmits water surface arrangement information including its own sensor identification information (sensor ID), time information, and position information to the underwater sensor device 3 by the underwater communication unit 15. An example of the configuration of the water surface arrangement information is shown in FIG. 5. The underwater communication unit 15 of the underwater sensor device 3 receives each water surface arrangement information from the three sea surface sensor devices 3-1, 3-2, and 3-3. The control unit 10 (position information acquisition unit) of the underwater sensor device 3 grasps its own position (water depth, latitude, longitude) based on "the distance Da between the sea surface sensor device 3 based on the communication delay time between the sea surface sensor device 3 by the underwater communication unit 15" and "the water surface arrangement information received by the underwater communication unit 15" for each of the three sea surface sensor devices 3-1, 3-2, and 3-3, and its own water depth H measured by the sensor unit 11.

Figure 6 is an explanatory diagram for explaining an example of a method for measuring the distance Da between the sea level sensor device 3 and the underwater sensor device 3. In Figure 6, the distance Da is measured using a passive method. In Figure 6, each sea level sensor device 3 transmits water surface location information to the underwater sensor device 3 at the same transmission time of "13:00:00". In the example of Figure 6, the underwater sensor device 3 receives the water surface location information of each sea level sensor device 3 at the same reception time of "13:00:01". From this communication delay time of "1 second", the distance Da between the underwater sensor device 3 and each sea level sensor device 3 is calculated to be "1.7 km". Sound waves propagate in the sea at approximately 1.7 km/s. In each sea level sensor device 3, the clock unit 12 is time-synchronized by the GPS unit 13.

Figure 7 is an explanatory diagram for explaining an example of a method for measuring the distance Da between the sea level sensor device 3 and the underwater sensor device 3. In Figure 7, the distance Da is measured using an active method. In Figure 7, the underwater sensor device 3 simultaneously transmits a predetermined confirmation signal to each sea level sensor device 3. When each sea level sensor device 3 receives a confirmation signal from the underwater sensor device 3, it returns a response signal to the underwater sensor device 3. The underwater sensor device 3 measures the round-trip delay time from transmitting the confirmation signal to receiving the response signal. In the example of Figure 7, the round-trip delay time between the underwater sensor device 3 and each sea level sensor device 3 is 1.5 seconds. From this round-trip delay time of 1.5 seconds, the distance Da between the underwater sensor device 3 and each sea level sensor device 3 is calculated.

This concludes the description of the underwater position determination method according to this embodiment.
As a result, the underwater sensors 3-4 and 3-5 of group Y grasp their current positions and move to their predetermined locations. As a result, the underwater sensors 3-4 and 3-5 of group Y move to their predetermined locations.

When the underwater sensor devices 3-6, 3-7, and 3-8 of group Z are able to communicate underwater with the sea surface sensor devices 3-1, 3-2, and 3-3 of group X, they determine their own positions and move to their designated locations in the same way as the underwater sensor devices 3-4 and 3-5 of group Y. This causes the underwater sensor devices 3-6, 3-7, and 3-8 of group Z to move to their designated locations.

On the other hand, when the underwater sensor devices 3-6, 3-7, and 3-8 of group Z are unable to communicate underwater with the sea surface sensor devices 3-1, 3-2, and 3-3 of group X, they use the underwater sensor devices 3 of group Y instead of group X to determine their current positions using the underwater position determination method of Figures 4-7 described above. In this case, at least three underwater sensor devices 3 of group Y are deployed. As a result, the underwater sensor devices 3-6, 3-7, and 3-8 of group Z determine their own positions and move to the specified positions.

(Step S3) The control unit 10 of the sensor device 3 determines its own position. This is to check whether the sensor device 3 has been carried away by ocean currents and deviated from its designated position after reaching the designated position in step S2.

(Step S4) The control unit 10 of the sensor device 3 determines whether or not its own position has shifted from the predetermined arrangement (position correction is necessary) as a result of determining its own position in step S3. If the result indicates that position correction is necessary, the process proceeds to step S5, and if not, the process proceeds to step S6.

(Step S5) The control unit 10 of the sensor device 3 controls the propulsion unit 18 to return its own position to the specified arrangement. This causes the sensor device 3 to return to the specified arrangement.

(Step S6) The control unit 10 of the sensor device 3 acquires sensor measurement data of a predetermined measurement item (e.g., water depth, water temperature, salinity concentration, etc.) measured by the sensor unit 11 at a predetermined measurement timing. The predetermined measurement timing is simultaneous for all sensor devices 3.

(Step S7) The control units 10 of the underwater sensor devices 3-4 and 3-5 of group Y transmit sensor measurement data for specific measurement items measured by the sensor units 11 at specific measurement timings to the sea surface sensor devices 3-1, 3-2, and 3-3 of group X via the underwater communication units 15.

The control unit 10 of the underwater sensor devices 3-6, 3-7, and 3-8 of group Z transmits sensor measurement data of specified measurement items measured by the sensor unit 11 at specified measurement timing to the underwater sensor devices 3-4 and 3-5 of group Y via the underwater communication unit 15. The underwater sensor devices 3-4 and 3-5 of group Y transfer the sensor measurement data received from the underwater sensor devices 3-6, 3-7, and 3-8 of group Z to the sea surface sensor devices 3-1, 3-2, and 3-3 of group X via the underwater communication unit 15.

The control units 10 of the sea surface sensor devices 3-1, 3-2, and 3-3 in group X hold their own sensor measurement data and the sensor measurement data of each of the underwater sensor devices 3-4, 3-5, 3-6, 3-7, and 3-8.

When a wireless link 101 is established between the sea surface sensor devices 3-1, 3-2, and 3-3 of group X and the base station BS by the water surface communication unit 14, the control unit 10 transmits the sensor measurement data it holds to the data collection device 5 by the water surface communication unit 14.

(Step S8) If the measurement is complete, end the process in FIG. 3; if not, return to step S3.

Next, we will explain a modified example of this embodiment.

(Variation 1)
When a sensor device 3 in a certain group becomes unable to communicate due to a failure or the like, the sensor devices 3 in the groups adjacent to that group (the group in which the failure occurred) are transferred to the group in which the failure occurred, thereby maintaining a balance in the number of sensor devices 3 belonging to each group.

(Variation 2)
The underwater sensor devices 3-6, 3-7, and 3-8 of group Z rise to the sea surface after a certain amount of time has passed since they were deployed in their designated locations. This is to charge the battery of the power supply unit 16 by solar power generation. When the underwater sensor devices 3-6, 3-7, and 3-8 of group Z rise to the sea surface, they receive a GPS signal by the GPS unit 13 and adjust the time in the clock unit 12 by the time information contained in the GPS signal.

Furthermore, when group Z rises to the sea surface, the sea surface sensor devices 3-1, 3-2, and 3-3 of group X move to the predetermined first depth of group Y, and the underwater sensor devices 3-4 and 3-5 of group Y move to the predetermined second depth of group Z. The latitude and longitude at this time remain the same as in the predetermined arrangement. After this, the processing from step S3 onwards in Figure 3 may be continued.

If bad weather reduces the amount of solar power generation and it takes longer than expected to charge the battery of the power supply unit 16, the timing of surfacing to the sea surface for solar power generation may be changed. The sea level sensor device 3 issues an instruction to change the timing of surfacing to the underwater sensor device 3 based on the results of monitoring the amount of power generated by its own solar power generation unit 17.

(Variation 3)
The sensor group can be used for both fixed-point measurement and dynamic measurement (measurement while the sensor group moves). In fixed-point measurement, the sensor group stays at the predetermined location described above and performs measurement. In dynamic measurement, an autonomous underwater vehicle (AUV) 40 is further provided as shown in FIG. 8. A sensor group consisting of multiple sensor devices 3 is placed at a water depth shallower than that of the AUV 40. The sensor group moves in accordance with the movement of the AUV 40. The AUV 40 grasps its own position based on the position information from the sensor group. In dynamic measurement, when a wireless link 101 between the sea surface sensor device 3 and the base station BS is established by the water surface communication unit 14, the control unit 10 of the sea surface sensor device 3 transmits the sensor measurement data held by the control unit 10 to the data collection device 5 by the water surface communication unit 14.

(Variation 4)
The modified example is an example of a method for correcting the interval between the sensor devices 3 due to the influence of ocean currents. FIG. 9 is an explanatory diagram of an example of the method for correcting the interval according to the present embodiment. FIG. 9 shows the arrangement of the sea level sensor device 3 and the underwater sensor device 3 as viewed from directly above the sea surface. The sea level sensor device 3 transmits information 50 to the underwater sensor device 3. The information 50 includes water surface arrangement information and speed information indicating the speed of the sea level sensor device 3. The underwater sensor device 3 estimates a position a to which the sea level sensor device 3 will move after a certain time based on the water surface arrangement information and speed information received from the sea level sensor device 3. Next, the underwater sensor device 3 calculates its own target position b after a certain time based on the estimated position a of the sea level sensor device 3 after a certain time. In addition, the underwater sensor device 3 estimates a position b' to which it will move after a certain time based on its own speed. Next, the underwater sensor device 3 adjusts its own moving direction and speed so that its own position after a certain time becomes the target position b. This corrects the deviation in the spacing between the sensor devices 3 caused by the influence of ocean currents.

(Variation 5)
When changing the arrangement of each water depth, a command to change the arrangement is given to the group (layer) of the water depth to be changed from the sensor device 3 of the layer immediately above. For example, for the layer to be changed,
10 and 11 show examples of the arrangement of the sensor device 3. In Fig. 10 and Fig. 11, a first layer is provided on the sea surface where GPS can be used, and a second, third and fourth layer are provided underwater for performing underwater communication.

When the sensor devices 3 on the third and fourth layers, which are deeper than the second layer, determine their own positions based on the position information of the sensor device 3 on the second layer, the position accuracy may be degraded. This is because the sensor device 3 on the second layer itself cannot obtain accurate position information using GPS. For this reason, the transmission output of the underwater communication unit 15 of the sensor device 3 on the first layer at the sea surface, where GPS is available, may be increased, and the sensor device 3 on the first layer may transmit water surface arrangement information including position information directly to the sensor devices 3 on the third and fourth layers. This allows the sensor devices 3 on the third and fourth layers to accurately determine their own positions based on the information transmitted from the sensor device 3 on the first layer.

Also, a set of sensor devices 3 on the second, third and fourth layers may be provided, each connected to a sensor device 3 on the first layer by an electric cable. The sensor devices 3 on the second, third and fourth layers of the set can be powered by the sensor device 3 on the first layer, eliminating the need to worry about running out of battery. This allows the sensor devices 3 on the second, third and fourth layers of the set to accurately grasp their own positions by constantly communicating with the sensor device 3 on the first layer.
In addition, a water depth corresponding to the water depth layer of the target for measuring the underwater state is set for each sensor device 3 in the same group. The water depth set for each sensor device 3 in the same group may be within the range of the target water depth layer. If the range of the target water depth layer of a certain group is, for example, from 10 m to 20 m, an arbitrary water depth within the range of 10 m to 20 m is set for each sensor device 3 in the group. For example, all sensor devices 3 in the same group may or may not be at the same water depth. For example, multiple sensor devices 3 at the same water depth may exist in the same group. For example, sensor devices 3 at different water depths may be mixed in the same group.

The above-described embodiment has the advantage that the underwater conditions can be precisely measured using multiple sensor devices 3.

Furthermore, according to this embodiment, the following effects can be obtained.
(1) It can measure underwater conditions while moving autonomously underwater, eliminating the need for manned ships and enabling measurements to be made even in bad weather.
(2) It will be possible to measure a wide area with higher spatial resolution than previous projects such as Argo. In addition, it will be possible to change the spatial resolution depending on the water depth. This will make a significant contribution to elucidating the actual state of changes in marine ecosystems.
(3) By taking solar power generation into consideration when ascent, the flight time of the sensor device 3 can be extended.
(4) When sending large volumes of observation data via satellite, it is necessary to mount a large antenna on the sensor at the sea surface. However, in this embodiment, the observation data is sent via the cellular network NW, so this is not necessary.
(5) By arranging a group consisting of multiple sensor devices 3 in multiple layers at different water depths, it is possible to measure underwater conditions in a three-dimensional and multifaceted manner.

Furthermore, this will enable us to improve the overall service quality of, for example, marine monitoring services, thereby contributing to Goal 13 of the United Nations' Sustainable Development Goals (SDGs), which is to "Take urgent action to combat climate change and its impacts."

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment and includes design modifications within the scope of the present invention.

For example, the operator may remotely give instructions to the sensor device. The sea level sensor device collects position information indicating the position of the submarine sensor device from the submarine sensor device. The sea level sensor device transmits position information indicating its own position and position information indicating the position of the submarine sensor device to the operator's terminal via a wireless line. The operator grasps the positions of the sea level sensor device and the submarine sensor device based on the position information of the sea level sensor device and the position information of the submarine sensor device. The operator uses the terminal to transmit the target position of the sea level sensor device and the target distance between the upper layer of the submarine sensor device to the sea level sensor device via a wireless line. The sea level sensor device autonomously moves to the target position. The sea level sensor device notifies the submarine sensor device of the target distance. The submarine sensor device autonomously moves so that the distance between itself and the upper layer becomes the target distance. This allows the sensor device to be placed at the position intended by the operator.

1...underwater observation system, 3...sensor device, 5...data collection device, 7...GPS satellite, 10...control unit, 11...sensor unit, 12...clock unit, 13...GPS unit, 14...surface communication unit, 15...underwater communication unit, 16...power supply unit, 17...solar power generation unit, 18...propulsion unit, BS...base station, NW...cellular network

Claims (10)

An underwater observation system having a plurality of sensor devices capable of autonomously moving on and underwater,
The sensor device includes:
A control unit;
A sensor unit for measuring a specific measurement item;
a time information acquisition unit that acquires time information indicating a current time;
a location information acquisition unit that acquires location information indicating a current location of the device;
A surface communication unit that performs wireless communication with a base station;
an underwater communication unit that communicates with a sensor device disposed underwater;
At least three of the sensor devices are disposed on the water surface;
A plurality of the sensor devices are disposed underwater;
In the water surface sensor device, which is the sensor device disposed on the water surface,
The control unit is
transmitting water surface arrangement information including the sensor identification information, the time information, and the position information to a sensor device arranged underwater by the underwater communication unit;
receiving sensor measurement data transmitted from a sensor device disposed underwater by the underwater communication unit;
The sensor measurement data received by the underwater communication unit is transmitted to a predetermined data collection device by the surface communication unit.
In the underwater sensor device, which is the sensor device disposed underwater,
The control unit is
receiving water surface arrangement information transmitted from at least three of the water surface sensor devices by the underwater communication unit;
transmitting sensor measurement data of a predetermined measurement item measured by the sensor unit at a predetermined measurement timing to the water surface sensor device via the underwater communication unit;
the position information acquisition unit calculates its own position based on a distance to the water surface sensor device based on a communication delay time between the underwater communication unit and the water surface sensor device, water surface arrangement information received by the underwater communication unit, and a water depth measured by the sensor unit;
the control unit controls the movement of the control unit based on the position of the control unit calculated by the position information acquisition unit and the position of the water surface sensor device so that the control unit and the water surface sensor device have a predetermined positional relationship.
Underwater observation system. When a sensor device in a first group consisting of a plurality of sensor devices arranged at a predetermined water depth becomes unable to communicate, a sensor device in a second group adjacent to the first group moves from a position of the second group to the first group, and the groups are reorganized in accordance with the movement .
10. The underwater observation system of claim 1. The sensor device further includes a solar power generation unit that generates solar power,
In the underwater sensor device,
the control unit controls the movement of the robot so that the robot floats to the water surface after a certain time has elapsed since the robot was placed in water.
3. An underwater observation system according to claim 1 or 2. When a group consisting of a plurality of sensor devices arranged at a predetermined water depth rises to the water surface, other groups move to the original water depth of the group.
4. The underwater observation system of claim 3. Further installing an autonomous underwater robot,
A sensor group consisting of a plurality of sensor devices is disposed at a water depth shallower than the autonomous underwater robot;
the sensor group performs underwater measurements while moving in accordance with the movement of the autonomous underwater robot;
An underwater observation system according to any one of claims 1 to 4. In the underwater sensor device,
The control unit is
estimating a position of the water surface sensor device after a certain time based on the water surface arrangement information and the speed information received from the water surface sensor device;
Calculate a target position of the water surface sensor device after a certain time based on the estimated position of the water surface sensor device after a certain time;
Estimating a location of the vehicle after a certain time based on the vehicle's speed;
Adjusting the direction and speed of movement of the robot so that the robot's position after a certain time period becomes the target position;
An underwater observation system according to any one of claims 1 to 5. At least one of the groups of underwater sensor devices arranged at a predetermined water depth is connected to the water surface sensor device by an electric cable and receives power from the water surface sensor device.
An underwater observation system according to any one of claims 1 to 6. A group of underwater sensor devices arranged at a predetermined water depth is arranged in a plurality of layers at different water depths,
An underwater observation system according to any one of claims 1 to 7. the water surface sensor device collects location information indicating a location of the underwater sensor device from the underwater sensor device;
the water surface sensor device transmits location information indicating its own location and location information indicating the location of the underwater sensor device to an operator terminal via the water surface communication unit;
the water surface sensor device receives a target position of the water surface sensor device and a target distance between the water surface sensor device and a higher layer of the underwater sensor device from the operator terminal via the water surface communication unit;
The water surface sensor device autonomously moves to the target position,
the water surface sensor device notifies the underwater sensor device of the target distance via the underwater communication unit;
The underwater sensor device autonomously moves so as to set the distance between itself and the upper layer to the target distance.
An underwater observation system according to any one of claims 1 to 8. An underwater observation method for an underwater observation system having a plurality of sensor devices capable of autonomously moving on and underwater, comprising:
The sensor device includes:
A control unit;
A sensor unit for measuring a specific measurement item;
a time information acquisition unit that acquires time information indicating a current time;
a location information acquisition unit that acquires location information indicating a current location of the device;
A surface communication unit that performs wireless communication with a base station;
an underwater communication unit that communicates with a sensor device disposed underwater;
At least three of the sensor devices are disposed on the water surface;
A plurality of the sensor devices are disposed underwater;
a step in which the control unit of the water surface sensor device, which is the sensor device arranged on the water surface, transmits water surface arrangement information including its own sensor identification information, the time information, and the position information to a sensor device arranged underwater by the underwater communication unit;
a step in which the control unit of the underwater sensor device, which is the sensor device disposed underwater, receives water surface arrangement information transmitted from at least three of the water surface sensor devices via the underwater communication unit;
a step in which the position information acquisition unit of the underwater sensor device calculates its own position based on a distance to the water surface sensor device based on a communication delay time between the underwater communication unit and the water surface sensor device, water surface arrangement information received by the underwater communication unit, and a water depth measured by the sensor unit;
a step in which the control unit of the underwater sensor device controls its own movement based on its own position calculated by the position information acquisition unit and the position of the water surface sensor device so that the underwater sensor device and the water surface sensor device have a predetermined positional relationship;
a step in which the control unit of the underwater sensor device transmits sensor measurement data of a predetermined measurement item measured by the sensor unit at a predetermined measurement timing to the water surface sensor device via the underwater communication unit;
a step in which the control unit of the water surface sensor device receives sensor measurement data transmitted from the underwater sensor device via the underwater communication unit;
A step in which the control unit of the water surface sensor device transmits the sensor measurement data received by the underwater communication unit to a predetermined data collection device via the water surface communication unit;
An underwater observation method comprising:

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