JP2018070125A - Underwater acoustic communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater acoustic communication system that expands a range in which underwater acoustic communication is possible between a ship or the like in the vicinity of a water surface and an underwater vehicle under water.SOLUTION: The underwater acoustic communication system, in which communication is performed by using an acoustic signal between floating acoustic communication means 30 disposed in the vicinity of a water surface A and a sailing body acoustic communication means 40 provided in an underwater vehicle 22 traveling in the water, includes acoustic communication relay means 50 disposed in a predetermined region X below the water surface A. At least when the underwater vehicle 22 travels beyond the predetermined region X, the floating acoustic communication means 30 and the sailing body acoustic communication means 40 perform acoustic communication via the acoustic communication relay means 50.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an underwater acoustic communication system that performs communication using an acoustic signal between a watercraft or the like on or near the water surface and an underwater vehicle that is thrown into the water.

In the ocean, lakes, etc., when investigating the bottom of the water by putting an underwater vehicle into the water, a device placed on the water or near the surface of the water and the underwater vehicle or underwater Communication with the underwater vehicle is performed using an underwater acoustic communication system using acoustic signals.
For example, in Patent Document 1, an underwater station cable-connected to a mother ship is placed in the sea, an acoustic transponder is placed on the sea floor near the exploration point, and an unmanned unmanned submersible for exploration is connected to the underwater station and the acoustic transponder. A technique is disclosed in which guidance is performed by communicating using an ultrasonic signal, and if necessary, an unmanned unmanned submersible is docked in an underwater station to perform charging or battery exchange and search data acquisition.
In Patent Document 2, an underwater station equipped with a first transponder, a first receiver and a second receiver is suspended from a mother ship into the sea, a second transponder is installed on the seabed, and an autonomous type for exploration. A third transponder and a third receiver are installed in the unmanned vehicle, and the underwater station receives the signal from the second transponder at the first receiver to maintain a fixed point. While the second transponder receives the signal from the second receiver by the third receiver, and when the power decreases, the first transponder receives the signal from the third receiver to move toward the underwater station. A technique is disclosed in which the underwater station performs attitude control for accommodating autonomous unmanned traveling by receiving a signal from a third transponder with a second receiver.
Patent Document 3 discloses a pixel signal in underwater acoustic communication in which a mother ship located on water is provided with a transmitter, a receiver is provided in an unmanned submersible for exploration, and a control signal is transmitted from the mother ship to the unmanned submersible. A technique for correcting a transmission error using the Hough transform is disclosed.
In Patent Document 4, a self-propelled repeater that relays communication between the mother ship and the underwater vehicle is arranged near the water surface in the observation area, and communication between the self-propelled repeater and the mother ship is radio wave communication. The technology which improves the communicable distance of a horizontal direction is performed by performing in communication and performing communication between a self-propelled repeater and an underwater vehicle by acoustic communication.

JP-A-3-266794 JP 2003-26090 A Japanese Patent Laid-Open No. 5-147583 JP 2001-308766 A Special table 2001-500901 gazette

When an underwater vehicle underwater such as a ship on or near the surface of the water performs underwater acoustic communication, generally the volume of the cone with the ship as the apex due to the reflection of the water surface of the sound wave However, it becomes an underwater acoustic communication possible area. However, it is conceivable that the underwater vehicle will leave the underwater acoustic communication area during observation work. When the underwater vehicle exceeds the underwater acoustic communication possible area, the underwater acoustic communication is interrupted.
In the invention described in Patent Document 1, since the mother ship and the underwater station are connected by a cable, the movement of the mother ship and the underwater station is restricted. Moreover, the influence on the acoustic communication by the sound wave reflecting off the water surface or the water bottom is not considered.
In the invention described in Patent Document 2, since the underwater station is suspended from the mother ship, movement of the mother ship and the underwater station is limited. Moreover, the influence on the acoustic communication by the sound wave reflecting off the water surface or the water bottom is not considered.
The invention described in Patent Document 3 considers that underwater acoustic communication is likely to be affected by reflected sound from the water surface or the seabed, and the unmanned submersible is in an uncontrolled state by estimating a correct control signal even if transmission errors are included. It is intended to prevent falling into. However, if the unmanned submarine exceeds the substantially conical underwater acoustic communication area with the mother ship at the top, communication is interrupted.
In the invention described in Patent Document 4, the acoustic communication deteriorates due to reflection from the sea surface and the sea floor, so that there is a region where the sound wave is not transmitted especially in the horizontal communication, and with the mother ship via the self-propelled repeater It is intended to increase the horizontal communicable distance by communicating with the underwater vehicle. However, since the self-propelled repeater is disposed in the vicinity of the water surface, it cannot communicate with the underwater vehicle that is outside the substantially conical underwater acoustic communication area with the self-propelled repeater as the apex.

  Then, this invention aims at providing the underwater acoustic communication system which expands the underwater acoustic communication possible range with the ship etc. which are in the water surface vicinity, and the underwater vehicle which is underwater.

In the underwater acoustic communication system corresponding to Claim 1, between the floating body acoustic communication means arrange | positioned in the vicinity of the water surface, and the navigation body acoustic communication means provided in the underwater vehicle which sails in water. In an underwater acoustic communication system that performs communication using an acoustic signal, an acoustic communication relay means disposed in a predetermined area in a substantially conical range that is downward from the surface of the water and is easily reachable by an acoustic signal transmitted by a floating acoustic communication means. The floating acoustic communication means and the navigation acoustic communication means perform acoustic communication via the acoustic communication relay means when at least the underwater vehicle travels beyond a predetermined area.
According to the first aspect of the present invention, the floating body acoustic communication unit and the navigation body acoustic communication unit can perform acoustic communication via the acoustic communication relay unit. Sound waves from the acoustic communication relay means arranged in the water are not easily affected by water surface reflection, and therefore easily reach the traveling body acoustic communication means outside the predetermined area. That is, since the range in which the floating body acoustic communication means and the navigation body acoustic communication means can perform acoustic communication is increased, the activity range of the underwater vehicle is expanded.
The "floating acoustic communication means arranged near the water surface" is located near the water surface even if all or most of the floating acoustic communication means provided on a buoy or the like floating on the water surface is submerged in water. Includes floating acoustic communication means. Moreover, the state mounted in floating bodies, such as a ship, shall also be included.

The present invention according to claim 2 is characterized in that the acoustic communication relay means is arranged in a low water temperature layer having a low underwater sound speed in a predetermined region.
According to the second aspect of the present invention, since the low water temperature layer is more likely to reach the far side in the horizontal direction, the communicable range via the acoustic communication relay unit between the floating body acoustic communication unit and the traveling body acoustic communication unit is provided. Expand further.

The present invention according to claim 3 is characterized in that the underwater acoustic communication system is used in the ocean, and the acoustic communication relay means is arranged in a low salinity layer having a low underwater sound speed in a predetermined region.
According to the third aspect of the present invention, since the low salinity layer is more likely to reach the farther horizontal sound wave, the communication range via the acoustic communication relay means between the floating acoustic communication means and the navigation acoustic communication means is increased. Expand further.

The present invention according to claim 4 is characterized in that the acoustic communication relay means is arranged at an optimum position in a predetermined area in accordance with the communication status of underwater acoustic communication grasped by the acoustic communication relay means.
According to the fourth aspect of the present invention, the stability of communication via the acoustic communication relay unit between the floating body acoustic communication unit and the traveling body acoustic communication unit is further increased.

The present invention according to claim 5 is characterized in that the communication status is a communication status between the acoustic communication relay means and the navigation vehicle acoustic communication means.
According to the fifth aspect of the present invention, the stability of communication is further increased, and the communicable range with the vehicle acoustic communication means is further expanded.

The invention according to claim 6 is characterized in that the acoustic communication relay means transmits acoustic signals in the lateral direction to perform acoustic communication with the navigation vehicle acoustic communication means.
According to the sixth aspect of the present invention, it is possible to stably communicate with the vehicle acoustic communication means that is particularly far away in the horizontal direction.

The present invention according to claim 7 is characterized in that when an underwater vehicle is present in a predetermined area, direct communication is performed between the floating acoustic communication means and the navigation acoustic communication means.
According to the seventh aspect of the present invention, the energy consumption and load of the acoustic communication relay means can be reduced, and the communication speed between the floating acoustic communication means and the navigation acoustic communication means can be increased.
Note that “direct communication” refers to communication that does not go through acoustic communication relay means.

The present invention according to claim 8 is characterized by comprising communication switching means for switching between direct communication between the floating acoustic communication means and the navigation acoustic communication means and indirect communication via the acoustic communication relay means.
According to the eighth aspect of the present invention, direct communication and indirect communication can be switched according to the communication status between the floating acoustic communication means and the navigation acoustic communication means, and if necessary.

The present invention according to claim 9 includes position data as data used for acoustic communication.
According to the ninth aspect of the present invention, by including the position data, correction of the position of the floating acoustic communication means, the acoustic communication relay means or the underwater vehicle and the association with the data acquired by the underwater vehicle Etc. can be performed.

The tenth aspect of the present invention is characterized in that the underwater vehicle and / or the acoustic communication relay means has storage means for storing data for use in acoustic communication.
According to the tenth aspect of the present invention, data can be retransmitted as necessary, or data can be verified after the underwater vehicle or acoustic communication relay means is recovered from the water.

The present invention according to claim 11 has a plurality of underwater vehicles and the acoustic communication relay means relays the acoustic signals of the plurality of underwater vehicles.
According to the present invention described in claim 11, the efficiency of observation work and the like can be improved by using a plurality of underwater vehicles.

The present invention according to claim 12 is characterized in that each of the plurality of underwater vehicles is equipped with an acoustic communication relay means, and the underwater vehicle existing in a predetermined area relays the acoustic communication.
According to the twelfth aspect of the present invention, the underwater vehicle itself can also serve as an acoustic communication relay function. In addition, by providing a plurality of acoustic communication relay means, indirect communication can be performed using the acoustic communication relay means mounted on another underwater vehicle even if one unit breaks down.

According to a thirteenth aspect of the present invention, the acoustic communication relay means is configured to be movable in water, and the moving speed of the acoustic communication relay means is slower than the traveling speed of the underwater vehicle. .
According to the thirteenth aspect of the present invention, since the acoustic communication relay means is movable, by tracking the floating acoustic communication means, even if the floating acoustic communication means moves, the acoustic communication relay means moves from the predetermined area. It can be prevented from coming off. In addition, since it is possible to move to a position where acoustic communication with the underwater vehicle is possible at most within a predetermined area of the substantially conical range, the observation range of the underwater vehicle can be expanded. Moreover, the energy consumption of the acoustic communication relay means can be saved to prepare for indirect communication by making the moving speed of the acoustic communication relay means slower than the traveling speed of the underwater vehicle.

The present invention according to claim 14 causes the underwater vehicle and / or the acoustic communication relay means to float on the water surface when acoustic communication between the traveling body acoustic communication means and the acoustic communication relay means becomes impossible. It is characterized by that.
According to the present invention as set forth in claim 14, the vehicle can be recovered before losing sight of the underwater vehicle and / or the acoustic communication relay means by ascending early.

In the present invention according to claim 15, after the underwater vehicle and / or the acoustic communication relay means have surfaced on the surface of the water, the communication between the floating acoustic communication means and the underwater vehicle and / or the acoustic communication relay means is performed in a space. It is characterized by switching to the used wireless communication.
According to the present invention as set forth in claim 15, communication between the floating acoustic communication means and the surfacing underwater vehicle and / or the acoustic communication relay means can be further performed stably by increasing the amount of information to a horizontal distance. .

  According to the underwater acoustic communication system of the present invention, the floating acoustic communication means and the navigation acoustic communication means can perform acoustic communication via the acoustic communication relay means. Sound waves from the acoustic communication relay means arranged in the water are not easily affected by water surface reflection, and therefore easily reach the traveling body acoustic communication means outside the predetermined area. That is, since the range in which the floating body acoustic communication means and the navigation body acoustic communication means can perform acoustic communication is increased, the activity range of the underwater vehicle is expanded.

  In addition, when the acoustic communication relay means is arranged in a low water temperature layer where the underwater sound speed is slow in the predetermined area, since the low water temperature layer is more likely to reach sound waves in the horizontal direction, the floating acoustic communication means and the navigation acoustic communication The communicable range via the acoustic communication relay means with the means is further expanded.

  In addition, when the underwater acoustic communication system is used in the ocean, and the acoustic communication relay means is placed in a low salinity layer where the underwater sound speed is slow in a predetermined area, the low salinity layer is more likely to reach the horizontal distance, so that the floating acoustics The communicable range of the communication means and the navigation vehicle acoustic communication means via the acoustic communication relay means is further expanded.

  In addition, according to the communication status of underwater acoustic communication grasped by the acoustic communication relay means, when the acoustic communication relay means is arranged at an optimal position in the predetermined area, the floating acoustic communication means, the navigation acoustic communication means, The stability of communication via the acoustic communication relay means is further increased.

  In addition, when the communication status is a communication status between the acoustic communication relay unit and the traveling body acoustic communication unit, the stability of communication is further increased, and the communicable range with the traveling body acoustic communication unit is further expanded.

  In addition, the acoustic communication relay means stably communicates with the traveling body acoustic communication means that is far away in the horizontal direction, particularly when the acoustic signal is transmitted in the lateral direction to perform acoustic communication with the traveling body acoustic communication means. It can be performed.

  In addition, when there is an underwater vehicle in a predetermined area, when performing direct communication between the floating acoustic communication means and the navigation acoustic communication means, energy consumption and load of the acoustic communication relay means can be reduced, The communication speed between the floating acoustic communication means and the navigation acoustic communication means can be increased.

  Further, in the case of including communication switching means for switching between direct communication between the floating acoustic communication means and the navigation acoustic communication means and indirect communication via the acoustic communication relay means, the floating acoustic communication means and the navigation acoustic communication means The direct communication and the indirect communication can be switched according to the communication status between and the direct communication.

  Further, when position data is included as data to be used for acoustic communication, correction of the position of the floating acoustic communication means, acoustic communication relay means or underwater vehicle, association with data acquired by the underwater vehicle, and the like are performed. be able to.

  In addition, when the underwater vehicle and / or the acoustic communication relay means have storage means for storing data to be used for acoustic communication, the data is retransmitted as necessary, the underwater vehicle or acoustic communication relay means The data can be verified after recovering from the water.

  In addition, when there are multiple underwater vehicles and the acoustic communication relay means relays the acoustic signals of multiple underwater vehicles, by using multiple underwater vehicles, Efficiency can be improved.

  In addition, when a plurality of underwater vehicles are equipped with acoustic communication relay means, and underwater vehicles in a predetermined area relay acoustic communication, the underwater vehicles themselves also function as an acoustic communication relay function. be able to. In addition, by providing a plurality of acoustic communication relay means, indirect communication can be performed using the acoustic communication relay means mounted on another underwater vehicle even if one unit breaks down.

  The acoustic communication relay means is configured to be movable in water, and the acoustic communication relay means is movable when the moving speed of the acoustic communication relay means is slower than the traveling speed of the underwater vehicle. Therefore, by tracking the floating acoustic communication means, it is possible to prevent the acoustic communication relay means from moving out of the predetermined area even if the floating acoustic communication means moves. In addition, since it is possible to move to a position where acoustic communication with the underwater vehicle is possible at most within a predetermined area of the substantially conical range, the observation range of the underwater vehicle can be expanded. Moreover, the energy consumption of the acoustic communication relay means can be saved to prepare for indirect communication by making the moving speed of the acoustic communication relay means slower than the traveling speed of the underwater vehicle.

  Also, when acoustic communication between the traveling body acoustic communication means and the acoustic communication relay means becomes impossible, when the underwater navigation body and / or the acoustic communication relay means are floated on the surface of the water, the aircraft is surfaced early. Thus, the underwater vehicle and / or the acoustic communication relay means can be recovered before losing sight.

  In addition, after the underwater vehicle and / or the acoustic communication relay means has surfaced, the communication between the floating acoustic communication means and the underwater vehicle and / or the acoustic communication relay means is switched to wireless communication using space. In addition, the communication between the floating acoustic communication means and the surfacing underwater vehicle and / or the acoustic communication relay means can further increase the amount of information and can be performed stably up to a horizontal distance.

1 is a schematic configuration diagram of an underwater acoustic communication system according to a first embodiment of the present invention. Diagram showing the relationship between depth and water temperature Diagram showing the relationship between depth and salinity Flow chart showing relay control of acoustic communication relay means Flow chart showing relay control of acoustic communication relay means The schematic block diagram of the underwater acoustic communication system by the 2nd Embodiment of this invention.

  Below, the underwater acoustic communication system by embodiment of this invention is demonstrated.

FIG. 1 is a schematic configuration diagram of an underwater acoustic communication system according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between depth (water depth) and water temperature, where the vertical axis represents depth [m] and the horizontal axis represents water temperature [° C.].
FIG. 3 is a diagram showing the relationship between depth (water depth) and salinity, where the vertical axis represents depth [m] and the horizontal axis represents salinity [permil].

FIG. 1 shows a state in which a floating acoustic communication means 30 is arranged near the water surface A in the ocean, a lake, and the like, a plurality of underwater robots 20 are inserted, and mineral resources and energy resources in the bottom B are searched. .
The ship 10 floating on the water surface A includes a floating acoustic communication means 30, communicates with the underwater robot 20 existing in the water where radio waves do not reach, using the acoustic signal, and monitors and controls the underwater robot 20. .
The underwater robot 20 is an unmanned autonomous underwater vehicle (AUV) that autonomously travels underwater without using a cable for connection to the floating acoustic communication means 30. Observe etc. By making the communication between the ship 10 and the underwater robot 20 acoustic communication instead of cable communication, it is not necessary to provide a facility for the cable in the ship 10, and the cable is entangled or the movement of the ship 10 is restricted by the cable. There is nothing to do.
The underwater acoustic communication system performs communication using acoustic signals between the floating acoustic communication means 30 and the navigation acoustic communication means 40 provided in the underwater robot 20.

The floating acoustic communication means 30 includes a transmitter that transmits sound waves and a receiver that receives sound waves, and is provided in the ship (investigation mother ship) 10 that floats on the water surface A.
The ship 10 can grasp the position of the ship by receiving a GNSS signal from a GNSS (Global Navigation Satellite System) satellite 1.
The ship 10 transmits a search-related command or the like from the floating acoustic communication unit 30 to the underwater robot 20, and the observation data transmitted from the underwater robot 20 is received by the floating acoustic communication unit 30.

The underwater robot 20 includes a single relay body 21 and a plurality of underwater vehicle bodies 22. The relay body 21 is equipped with an acoustic communication relay means 50, a communication switching means 60, and a storage means 70. Observation of the bottom B is mainly performed by the underwater vehicle 22, but the relay body 21 can also observe the bottom B and the like.
The vehicle acoustic communication means 40 includes a transmitter that transmits sound waves and a receiver that receives sound waves. The relay body 21 is provided with relay body acoustic communication means 41 as the navigation body acoustic communication means 40, and the underwater navigation body 22 is provided with navigation body acoustic communication means 42 as the navigation body acoustic communication means 40. ing.
The relay body 21 and the underwater vehicle 22 transmit observation data and the like obtained by observation to the ship 10 from the relay body acoustic communication means 41 and the navigation body acoustic communication means 42, and send commands and the like transmitted from the ship 10. It is received by the relay body acoustic communication means 41 and the navigation body acoustic communication means 42.
The acoustic communication relay means 50 mounted on the relay body 21 relays the acoustic communication between the ship 10 and the underwater vehicle 22. Thereby, the ship 10 and the underwater vehicle 22 can perform indirect communication via the acoustic communication relay means 50 of the relay body 21.
Like this embodiment, it has two or more underwater vehicles 22, and the relay body 21 relays the acoustic signal transmitted / received between the plurality of underwater vehicles 22 and the ship 11, and is efficient. Underwater exploration can be performed.

In the present embodiment, when the underwater vehicle 22 exists in the predetermined area X, the underwater vehicle 22 existing in the predetermined area X includes the acoustic communication relay unit 50 of the relay body 21. Direct communication without intervention. This reduces energy consumption and load of the acoustic communication relay means 50 of the relay body 22 and improves the communication speed between the ship 10 and the underwater vehicle 22 compared to indirect communication.
In FIG. 1, solid arrows indicate underwater acoustic communication.
The relay body 21 includes a communication switching unit 60 that switches between direct communication and indirect communication, and performs direct communication and indirect communication according to the communication status between the ship 10 and the underwater vehicle 22 or as necessary. Can be switched. When the ship 10 and the underwater vehicle 22 always perform indirect communication, the communication switching means 60 can be omitted.

When acoustic communication is performed between the ship 10 and the underwater robot 20, the sound wave transmitted downward is reflected by the water surface A, and acoustic communication in the horizontal direction and the depression direction close thereto is particularly difficult. As shown in FIG. 1, the region where the acoustic signal transmitted from the ship 10 is likely to reach is a predetermined region X that is a substantially conical range with the floating acoustic communication means 30 as a vertex.
The relay body 21 is located below the water surface A and is disposed in a predetermined area X where the acoustic signal from the ship 10 can easily reach, and is controlled not to travel beyond the predetermined area X. By keeping the relay body 21 within the predetermined region X, it is possible to prevent the acoustic communication between the ship 10 and the relay body 21 from being interrupted.
In addition, since the acoustic signal transmitted from the relay body 21 disposed in the water is less affected by water surface reflection, the horizontal reach is wider than the acoustic signal transmitted from the ship 10. Therefore, the relay body 21 can easily perform acoustic communication with the underwater vehicle 22 even when the underwater vehicle 22 is outside the predetermined region X.
Therefore, the acoustic communication between the ship 10 and the underwater vehicle 22 is at least when the underwater vehicle 22 is traveling beyond the predetermined region X, and the acoustic communication relay means 50 mounted on the relay body 21. By performing indirect communication via the communication, communication interruption can be avoided. Thereby, the range in which the acoustic communication between the ship 10 and the underwater vehicle 22 can be expanded, and the range in which the underwater vehicle 22 can be searched is expanded.
The deeper the position of the relay body 21, the smaller the influence of water surface reflection on the acoustic signal transmitted from the relay body acoustic communication means 41. However, when the relay body 21 gets too close to the bottom B, it is reflected at the bottom B. Since the influence of sound waves (water bottom reflection) is increased, it is preferable to consider not only the depth from the water surface A but also the altitude from the water bottom B. In this case, since the shape of the bottom B is more complicated than the water surface A and the bottom reflection is also complicated, it is more preferable to consider the altitude depending on the shape of the bottom B. The reachable range of the acoustic signal transmitted from the relay body 21 in the horizontal direction can be estimated from the depth and altitude at which the relay body 21 is located, the incident / reflection angle of the sound wave toward the water surface A and the bottom B, and the like.

The relay body 21 which is AUV can move following the movement of the ship 10 by a vertical thruster or a horizontal thruster, or can maintain a position even in a place where there is a water flow or the like. Therefore, as in this embodiment, the acoustic communication relay unit 50 is mounted on the relay body 21, that is, the acoustic communication relay unit 50 is configured to be movable, so that the acoustic communication relay unit 50 remains in the predetermined region X. Can do. In addition, since the relay body 21 can move to a position where acoustic communication with the underwater vehicle 22 is possible within the predetermined area X, the observation range of the underwater vehicle 22 can be expanded. Can do.
In addition, since the relay body 21 remains in the predetermined region X, the moving range is narrower than the underwater vehicle 22. Therefore, the traveling speed of the relay body 21 may be slower than the traveling speed of the underwater vehicle 22. By suppressing the traveling speed of the relay body 21, energy consumption of the relay body 21 can be saved and prepared for indirect communication.

The position in the vertical direction of the relay body 21 on which the acoustic communication relay means 50 is mounted is determined so as to be a position where acoustic communication can be performed with the underwater vehicle 22 outside the predetermined area X.
It is preferable to arrange the relay body 21 at an optimal position in the predetermined region X according to the communication status of underwater acoustic communication grasped by the relay body acoustic communication means 41. By arranging the relay body 21 with the acoustic communication relay means 50 mounted at a position where the communication condition is good in the predetermined area X, the ship 10 and the underwater vehicle 22 perform indirect communication via the acoustic communication relay means 50. The stability of communication when performing is further increased. The communication status of underwater acoustic communication is grasped by, for example, a signal / noise ratio (S / N ratio).
In determining the optimum position, the communication state between the relay body 21 and the ship 10 may be followed. However, the relay body 21 is arranged at the optimum position according to the communication state between the relay body 21 and the underwater vehicle 22. In this case, the stability of communication is further enhanced, and the range of acoustic communication with the underwater vehicle 22 can be further expanded.
Moreover, you may arrange | position the relay body 21 in the low water temperature layer with a slow underwater sound speed among the predetermined area | region X. FIG. When the water temperature is in the range of about 3 to 74 ° C., the lower the water temperature, the lower the sound speed in water, and the more easily the sound waves reach farther to the horizontal, so by placing the relay body 21 in the low water temperature layer where the water temperature is lower than the others, The range in which acoustic communication is possible between the vehicle 10 and the underwater vehicle 22 via the acoustic communication relay means 50 is further expanded. Here, FIG. 2 is a diagram showing the relationship between the depth and the water temperature created based on the survey in the sea area with a water depth of 1700 m or more. From FIG. 2, it can be seen that the water temperature in this sea area is in the range of 3 to 74 ° C. where the underwater sound speed becomes slower as the water temperature is lower, and tends to decrease as the distance from the water surface A increases. Therefore, when only the water depth and the water temperature are considered, it is preferable to make the position of the relay body 21 in the vertical direction deeper. However, when there is a hydrothermal deposit at the bottom of the water and there is a high water temperature layer where the temperature of the water is higher than the others, the high water temperature layer is avoided. In this way, by measuring or estimating the water temperature change due to the depth and arranging the relay body 21 in a place where the water temperature is lower in the predetermined region X based on the result, the acoustic communication possible range is further increased as described above. Expanding.
Moreover, when using an underwater acoustic communication system in the ocean, you may arrange | position the relay body 21 in the low salinity layer whose salinity is lower than the others in the predetermined area X. The lower the salinity, the slower the sound velocity in the water and the easier it is for sound waves to reach further horizontally. Therefore, by arranging the relay body 21 in the low salinity layer, the acoustic communication relay means 50 between the ship 10 and the underwater vehicle 22 is provided. The range in which acoustic communication can be further expanded. As a result of investigating the relationship between depth and salinity in a sea area with a water depth of 1700 m or more, it was found that a depth of about 400 to 600 m was the lowest salinity layer as shown in FIG. In addition, if the water depth is about 400 m or more, a depth of about 400 to 600 m is a low salinity layer regardless of the maximum depth. Therefore, when considering only the water depth and salinity, it is preferable to arrange the relay body 21 at a depth of about 400 to 600 m in the predetermined area X in the sea area where the water depth is about 400 m or more. In addition, when both the water temperature and the salinity are low, the underwater sound speed is further slower than when only one of them is low, so it is more preferable to determine the position of the relay body 21 based on both the water temperature and the salinity. Since the pressure (depth) also affects the underwater sound speed, the position of the relay body 21 may be determined in consideration of this pressure.

A method for determining the position of the relay body 21 on which the acoustic communication relay means 50 is mounted will be described in further detail.
Mackenzie's equation (Equation 1) is an equation that approximates the relationship between water temperature, salinity, water depth, and underwater sound speed.
here,
c: Sound velocity (m / s)
T: Water temperature (° C)
S: salt (permil)
D: Water depth (m)
It is.
When considering the water temperature, salinity, and water depth, it is preferable to obtain the sound speed according to the Mackenzie equation.

Using the relationship between water depth and water temperature shown in FIG. 2 and the relationship between water depth and salinity shown in FIG. 3 and calculating the speed of sound in consideration of the water temperature, salinity and water depth based on the above equation 1, The result is as follows.
In this case, the water depth (sound speed minimum point) at which the sound speed is the smallest is 1000 m, and the water depth from 600 m to 1400 m can be said to be a slow sound layer where the sound speed is 1490 m / s or less. Furthermore, it can be said that the depth of water from 800 m to 1200 m is a sound velocity minimum layer where the sound velocity at which the sound velocity is 1486 m / s or less is slower.
In the sea area where the water temperature of the water surface A is as high as 30 ° C., as shown in FIG. In the sea area where the water temperature of the water surface A is low, the influence of changes in water depth and salinity prevails over changes in water temperature.
Layers with slow sound speed vary depending on the water temperature profile, salinity profile, and water depth, so for accuracy, the sound speed is appropriately adjusted according to the water temperature profile, salinity profile, and water depth of the applicable sea area. It is preferable to obtain the layer that slows down using Equation 1 or the like. For more accuracy, it is possible to measure the water temperature, salinity, and water depth, for example, with the acoustic communication relay means 50, calculate the sound speed based on Equation 1 and the like, and place the acoustic communication relay means 50 in a layer with a low sound speed. preferable. Moreover, it is more preferable to arrange the acoustic communication relay means 50 in the sonic minimum layer.

  As described above, the underwater acoustic signal transmitted from the relay body 21 disposed in the water is less affected by water surface reflection, and thus the horizontal reach is longer than the underwater acoustic signal transmitted from the ship 10. . Therefore, when the relay body 21 transmits an acoustic signal in the horizontal direction (horizontal direction) and performs acoustic communication with the underwater vehicle 22, the underwater vehicle 22 that is far away in the horizontal direction is particularly stable. Can communicate.

The relay body 21 and the underwater vehicle 22 are provided with storage means 70 such as a hard disk drive and a semiconductor memory for storing data used for acoustic communication. Or the data can be verified after the acoustic communication relay means 50 is recovered from the water.
The data used for acoustic communication can include position data such as the self position and the observation position. By including the position data, it is possible to correct the position of the ship 10, the relay body 21, or the underwater vehicle 22, or to associate the data with the data acquired by the underwater vehicle 22.

When acoustic communication between the relay body acoustic communication means 41 of the relay body 21 and the navigation body acoustic communication means 42 of the underwater vehicle 22 becomes impossible, the relay body 21 and the underwater vehicle 22 are floated on the water surface A. May be.
By ascending early, the relay body 21 and the underwater vehicle 22 can be recovered before losing sight.
In addition, after the relay body 21 and the underwater vehicle 22 have surfaced on the water surface A, it is preferable to switch the communication between the ship 10 and the relay body 21 and the underwater vehicle 22 to wireless communication using a space.
Since sound waves are difficult to reach on the water, switching to wireless communication facilitates communication even if the distance between the ship 10 and the surfacing relay body 21 or the underwater navigation body 22 is long. Note that radio communication, optical communication, acoustic communication, and the like can be used as wireless communication using space.

The plurality of underwater vehicles 22 are each equipped with the acoustic communication relay means 50, and in addition to the relay body 21 or instead of the relay body 21, the underwater vehicle 22 existing in the predetermined region X is acoustically connected to the ship 10. Communication relay may be performed.
Thereby, the underwater vehicle 22 itself can also serve as a function of relaying acoustic communication. In addition, each of the plurality of underwater vehicles 22 includes the acoustic communication relay means 50, so that even if one unit breaks down, indirect communication is performed using the acoustic communication relay means 50 mounted on another underwater vehicle 22. Can be done.

  Next, an underwater acoustic communication system according to the second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same functional member as 1st Embodiment, and description is abbreviate | omitted.

FIG. 4 is a schematic configuration diagram of an underwater acoustic communication system according to the second embodiment of the present invention.
This embodiment is provided with an offshore surface vehicle (ASV) 11, a ship (investigation mother ship) 10 is provided with a ship acoustic communication means 31 as a floating acoustic communication means 30, and the offshore repeater 11 is provided with a floating body sound. It differs from the first embodiment in that an offshore repeater acoustic communication means 32 is provided as the communication means 30. Communication between the ship 10 and the offshore repeater 11 is performed by radio communication using radio waves. By using the offshore repeater 11, the activity range of the underwater vehicle 22 can be further expanded.

The ship 10 and the offshore repeater 11 can grasp their own positions by receiving the GNSS signal from the GNSS satellite 1.
The offshore repeater 11 is used in a semi-submersible state in which the main body 11A is submerged in water and located at a depth of about 1.5 m, and the upper part of the antenna 11B protrudes above the water surface A.
The ship 10 and the offshore repeater 11 transmit a search-related command and the like from the ship acoustic communication unit 31 and the offshore repeater acoustic communication unit 32 to the underwater robot 20, and the observation data transmitted from the underwater robot 20 is transmitted to the ship acoustic communication unit. 31. Received by the offshore repeater acoustic communication means 32.

The relay body 21 and the underwater vehicle 22 transmit observation data and the like obtained by observation to the ship 10 and the offshore repeater 11 from the relay body acoustic communication means 41 and the navigation body acoustic communication means 42. A command transmitted from the repeater 11 is received by the relay acoustic communication means 41 and the navigation acoustic communication means 42.
The acoustic communication relay means 50 mounted on the relay body 21 relays the acoustic communication between the ship 10 and the underwater vehicle 22. Thereby, the ship 10 and the underwater vehicle 22 can perform indirect communication via the acoustic communication relay means 50 of the relay body 21.

The relay body 21 is located below the water surface A and is disposed in a predetermined area X where the acoustic signal from the ship 10 can easily reach, and is controlled not to travel beyond the predetermined area X.
The underwater vehicle 22 is disposed below the water surface A and in a predetermined region Y where an acoustic signal from the offshore repeater 11 is easily reached.
The acoustic communication between the ship 10 and the underwater vehicle 22 is an acoustic communication relay mounted on the relay body 21 at least when the underwater vehicle 22 is traveling beyond the predetermined region X and the predetermined region Y. By performing indirect communication via the means 50, communication interruption can be avoided. Thereby, the range in which the acoustic communication between the ship 10 and the underwater vehicle 22 can be expanded, and the range in which the underwater vehicle 22 can be searched is expanded.

  The relay body 21 may be arranged in the predetermined area Y and controlled so as not to travel beyond the predetermined area Y. In this case, since the communication between the relay body 21 and the ship 10 is performed via the offshore repeater 11, the ship 10 can omit the ship acoustic communication means 31 and is not affected by the position of the relay body 21. You can sail.

  Next, an example of relay control of the acoustic communication relay unit 50 will be described with reference to FIGS. 5 and 6. Although the description will focus on the first embodiment, the second embodiment is basically the same.

FIG. 5 is a flowchart showing relay control of the acoustic communication relay means when the establishment of acoustic communication is requested from the ship to the underwater vehicle.
When the ship 10 requests the underwater vehicle 22 to establish acoustic communication, the ship 10 transmits a first acoustic signal for requesting a response to the underwater vehicle 22 from the floating body acoustic communication means 30. Since the sound wave is omnidirectional, the first acoustic signal transmitted by the floating acoustic communication means 30 is also received by the relay acoustic communication means 41 of the relay body 21 in the predetermined area X. When the relay acoustic communication means 41 receives the first acoustic signal, the relay control of the acoustic communication relay means 50 starts (step 1). In the second embodiment, the ship 10 transmits a signal for requesting a response to the underwater vehicle 22 to the offshore repeater 11 by wireless communication, and the ship acoustics as the first acoustic signal. A call is sent from the communication means 31. A signal by wireless communication is converted into an acoustic signal by the offshore repeater 11 and transmitted from the offshore repeater acoustic communication means 32 as a first acoustic signal.
When the traveling body acoustic communication means 42 receives the first acoustic signal transmitted in step 1, the underwater traveling body 22 receives the second acoustic signal that informs that the first acoustic signal has been received. Originating from the acoustic communication means 42. After the first acoustic signal transmitted in step 1 is received by the acoustic communication relay means 50, has the relay acoustic communication means 41 received the second acoustic signal that should be transmitted from the underwater vehicle 22? It is determined whether or not (step 2).
If it is determined in step 2 that the relay acoustic communication means 41 has received the second acoustic signal, the acoustic communication relay means 50 ends the relay control as it is (step 3). This is because it can be determined that direct communication between the ship 10 and the underwater vehicle 22 is possible. In this case, the acoustic communication between the ship 10 and the underwater vehicle 22 is performed by direct communication not via the relay body 21.
If it is determined in step 2 that the second acoustic signal is not received by the relay acoustic communication means 41, the acoustic communication relay means 50 uses the first acoustic signal received in step 1 as the relay acoustic communication. A call is made from the means 41 (step 4). This is because it can be determined that the first acoustic signal transmitted in step 1 has not reached the vehicle acoustic communication means 42.
When the traveling body acoustic communication means 42 receives the first acoustic signal transmitted in step 4, the underwater traveling body 22 receives the second acoustic signal that informs that the first acoustic signal has been received. Originating from the acoustic communication means 42. After transmitting the first acoustic signal in step 4, the acoustic communication relay unit 50 determines whether the relay unit acoustic communication unit 41 has received the second acoustic signal that should be transmitted from the underwater vehicle 22. Judgment is made (step 5).
If it is determined in step 5 that the second acoustic signal has been received by the relay acoustic communication unit 41, the acoustic communication relay unit 50 switches to indirect communication by the communication switching unit 60 (step 6). This is because it can be determined that indirect communication between the ship 10 and the underwater vehicle 22 is possible. In this case, acoustic communication between the ship 10 and the underwater vehicle 22 is performed by indirect communication via the relay body 21.
If it is determined in step 5 that the second acoustic signal has not been received by the relay acoustic communication means 41, the acoustic communication relay means 50 ends the relay control as it is (step 7). This is because it can be determined that indirect communication between the ship 10 and the underwater vehicle 22 is also impossible. The relay body 21 may be levitated and collected. In the second embodiment, even in this case, there is a possibility that the ship 10 and the underwater vehicle 22 can communicate via the offshore repeater 11. Therefore, an acoustic signal indicating whether or not the ship 10 has received the second acoustic signal converted into radio waves by the offshore repeater 11 is transmitted from the ship acoustic communication means 31 to the relay body 21. Good.

  In the ship 10, when the floating acoustic communication means 30 does not receive the second acoustic signal, an acoustic signal for requesting a response as to whether or not the first acoustic signal has been transmitted (the operation of step 4 has been performed) is sent to the floating body. The first acoustic signal transmitted from the acoustic communication unit 30 to the relay body 21 or transmitted from the relay body acoustic communication unit 41 in step 4 may be received by the floating body acoustic communication unit 30.

FIG. 6 is a flowchart for explaining the relay control of the acoustic communication relay unit when the establishment of acoustic communication is requested from the underwater vehicle to the ship.
When the underwater vehicle 22 requests the ship 10 to establish acoustic communication, the underwater vehicle 22 transmits a third acoustic signal for requesting a response from the ship 10 from the vehicle acoustic communication means 42. There is a possibility that the omnidirectional third acoustic signal transmitted by the traveling body acoustic communication means 42 can be received also by the relay acoustic communication means 41. When the relay acoustic communication means 41 receives the third acoustic signal, the relay control of the acoustic communication relay means 50 starts (step 11). In the second embodiment, the third acoustic signal that has reached the offshore repeater 11 is converted into a radio wave and transmitted to the ship 10 by wireless communication.
When the floating acoustic communication means 30 receives the third acoustic signal transmitted in step 11, the ship 10 transmits a fourth acoustic signal from the floating acoustic communication means 30 informing that the third acoustic signal has been received. . After receiving the third acoustic signal transmitted in step 11, the acoustic communication relay means 50 determines whether the relay acoustic communication means 41 has received the fourth acoustic signal that should be transmitted from the ship 10. Judgment is made (step 12). In the second embodiment, the ship 10 transmits a signal notifying that the third acoustic signal has been received to the offshore repeater 11 by wireless communication, and the ship acoustics as the fourth acoustic signal. A call is sent from the communication means 31. The signal by wireless communication is converted into an acoustic signal by the offshore repeater 11 and transmitted from the offshore repeater acoustic communication means 32 as a fourth acoustic signal.
If it is determined in step 12 that the relay acoustic communication means 41 has received the fourth acoustic signal, the acoustic communication relay means 50 ends the relay control as it is (step 13). This is because it can be determined that direct communication between the ship 10 and the underwater vehicle 22 is possible. In this case, the acoustic communication between the ship 10 and the underwater vehicle 22 is performed by direct communication not via the relay body 21.
If it is determined in step 12 that the fourth acoustic signal is not received by the relay acoustic communication unit 41, the acoustic communication relay unit 50 uses the third acoustic signal received in step 11 as the relay acoustic communication. A transmission is made from the means 41 (step 14). This is because it can be determined that the third acoustic signal transmitted in step 11 has not reached the floating acoustic communication means 30.
When the floating acoustic communication unit 30 receives the third acoustic signal transmitted in step 14, the ship 10 transmits a fourth acoustic signal that informs that the third acoustic signal has been received from the floating acoustic communication unit 30. . The acoustic communication relay means 50 determines whether or not the relay acoustic communication means 41 has received the fourth acoustic signal that should be transmitted from the ship 10 after transmitting the third acoustic signal in step 14 ( Step 15). In the second embodiment, the ship 10 transmits a signal notifying that the third acoustic signal has been received to the offshore repeater 11 by wireless communication, and the ship acoustics as the fourth acoustic signal. A call is sent from the communication means 31. The signal by wireless communication is converted into an acoustic signal by the offshore repeater 11 and transmitted from the offshore repeater acoustic communication means 32 as a fourth acoustic signal.
In step 15, when it is determined that the fourth acoustic signal is received by the relay acoustic communication unit 41, the acoustic communication relay unit 50 transmits the received fourth acoustic signal from the relay acoustic communication unit 41. At the same time, the communication switching means 60 switches to indirect communication (step 16). This is because it can be determined that indirect communication between the ship 10 and the underwater vehicle 22 is possible. In this case, acoustic communication between the ship 10 and the underwater vehicle 22 is performed by indirect communication via the relay body 21.
If it is determined in step 15 that the fourth acoustic signal is not received by the relay acoustic communication means 41, the acoustic communication relay means 50 ends the relay control as it is (step 17). This is because it can be determined that indirect communication between the ship 10 and the underwater vehicle 22 is also impossible. The relay body 21 may be levitated and collected. Further, in this case, since the fourth acoustic signal does not reach the traveling body acoustic communication means 42, a command to ascend when the fourth acoustic signal is not received for a predetermined time to the underwater traveling body 22 is provided. By giving in advance, the underwater vehicle 22 can be levitated and collected. In the second embodiment, even in this case, there is a possibility that the ship 10 and the underwater vehicle 22 can communicate via the offshore repeater 11. Therefore, an acoustic signal indicating whether or not the ship 10 has received the third acoustic signal converted into radio waves by the offshore repeater 11 is transmitted from the ship acoustic communication means 31 to the relay body 21. Good.

  The underwater acoustic communication system of the present invention can expand the range in which acoustic communication between a ship near the water surface and the underwater robot can be expanded during underwater exploration in the ocean, lakes and the like. Exploration can be performed.

22 underwater vehicle 30 floating body acoustic communication means 40, 42 navigation body acoustic communication means 50 acoustic communication relay means 60 communication switching means 70 storage means A water surface X predetermined area

Claims (15)

  In an underwater acoustic communication system that performs communication using acoustic signals between a floating acoustic communication means arranged near the water surface and a traveling body acoustic communication means provided in an underwater vehicle traveling in water An acoustic communication relay unit disposed in a predetermined region in a substantially conical range that is lower than the water surface and is easy to reach the acoustic signal transmitted by the floating acoustic communication unit, and at least the underwater vehicle is the predetermined An underwater acoustic communication system, wherein the floating acoustic communication means and the navigation acoustic communication means perform acoustic communication via the acoustic communication relay means when sailing beyond an area.   The underwater acoustic communication system according to claim 1, wherein the acoustic communication relay unit is arranged in a low water temperature layer having a low underwater sound speed in the predetermined region.   3. The underwater acoustic communication system according to claim 1, wherein the underwater acoustic communication system is used in the ocean, and the acoustic communication relay unit is arranged in a low salinity layer having a low underwater sound speed in the predetermined region. .   4. The acoustic communication relay unit is arranged at an optimum position in the predetermined area in accordance with a communication status of the acoustic communication in the water grasped by the acoustic communication relay unit. The underwater acoustic communication system according to 1 above.   The underwater acoustic communication system according to claim 4, wherein the communication status is a communication status between the acoustic communication relay unit and the navigation vehicle acoustic communication unit.   The said acoustic communication relay means transmits the said acoustic signal to a horizontal direction, and performs the said acoustic communication with the said navigation body acoustic communication means, The one of Claims 1-5 characterized by the above-mentioned. Underwater acoustic communication system.   The direct communication between the floating body acoustic communication unit and the navigation body acoustic communication unit is performed when the underwater vehicle is present in the predetermined region. The underwater acoustic communication system described in 1.   8. The underwater sound according to claim 7, further comprising communication switching means for switching between the direct communication of the floating acoustic communication means and the navigation acoustic communication means and indirect communication via the acoustic communication relay means. Communications system.   The underwater acoustic communication system according to claim 1, wherein position data is included as data used for the acoustic communication.   10. The underwater sound according to claim 1, further comprising a storage unit that stores data to be used for the acoustic communication in the underwater vehicle and / or the acoustic communication relay unit. Communications system.   11. The vehicle according to claim 1, wherein the underwater vehicle has a plurality of underwater vehicles, and the acoustic communication relay unit relays the acoustic signals of the plurality of underwater vehicles. Underwater acoustic communication system.   The underwater sound according to claim 11, wherein a plurality of the underwater vehicles are equipped with the acoustic communication relay means, and the underwater vehicles existing in the predetermined area relay the acoustic communication. Communications system.   12. The acoustic communication relay unit is configured to be movable in water, and the moving speed of the acoustic communication relay unit is slower than the traveling speed of the underwater vehicle. The underwater acoustic communication system according to one of the above.   The underwater vehicle and / or the acoustic communication relay means are floated on the water surface when the acoustic communication between the navigation body acoustic communication means and the acoustic communication relay means cannot be performed. The underwater acoustic communication system according to claim 1.   After the underwater vehicle and / or the acoustic communication relay means have surfaced on the water surface, the wireless communication using the space is used for communication between the floating acoustic communication means and the underwater vehicle and / or the acoustic communication relay means. It switches to communication, The underwater acoustic communication system of Claim 14 characterized by the above-mentioned.