Communication system, underwater light communication body, and control method

Abstract

To provide a communication system, an underwater light communication body, and a control method for performing underwater light wireless communication.SOLUTION: A communication system 10 comprises: a second underwater light communication body 200 that includes a second light communication section 210 including a second light antenna 212, a second laser unit 220 including a plurality of second laser irradiation sections 230, and a second control section 270 for irradiating the plurality of second laser irradiation sections with laser light in order; and a first underwater light communication body 100 that includes a first light communication section 110 including a first light antenna 112, a first laser unit 120 including a plurality of first laser light reception sections 150, and a first control section 170 for detecting the second laser unit on the basis of laser light received by at least any of the plurality of first laser light reception sections, estimating a relative direction of the second laser unit on the basis of a time series laser light reception situation by the plurality of first laser light reception sections, and controlling a movement mechanism 182 in order to perform positioning with the second laser unit on the basis of the relative direction to adjust a direction of light communication of the first light communication section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication system, an underwater optical communication device, and a control method. [Background technology]

[0002] Submersible vehicles have been known that are equipped with optical wireless communication devices and are capable of performing optical wireless communication with other submersible vehicles via optical wireless communication (see, for example, Patent Document 1). [Prior art document] [Patent Documents] [Patent Document 1] Patent No. 6792686 Summary of the Invention [Means for solving the problem]

[0003] According to one embodiment of the present invention, there is provided a communication system for underwater optical wireless communication. The communication system may include a first underwater optical communication device movable underwater. The communication system may include a second underwater optical communication device. The second underwater optical communication device may include a second optical communication unit including a second optical antenna. The second underwater optical communication device may include a second laser unit including a plurality of second laser emitting units that emit laser light in the direction of optical communication of the second optical communication device. The second underwater optical communication device may include a second control unit that controls the plurality of second laser emitting units to emit laser light in sequence. The first underwater optical communication device may include a first optical communication unit including a first optical antenna. The first underwater optical communication device may include a first laser unit that receives laser light from the direction of optical communication of the first optical communication device and includes a plurality of first laser receiving units arranged in the same arrangement as the plurality of second laser emitting units. The first underwater optical communication device may have a first control unit that detects the second laser unit based on the laser light received by at least one of the multiple first laser receiving units, estimates the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the multiple first laser receiving units, controls the movement mechanism of the first underwater optical communication device to align the first laser unit with the second laser unit based on the relative direction, and controls the direction of optical communication of the first optical communication unit to adjust based on the light from the second optical antenna received by the first optical antenna.

[0004] In the communication system, the second laser emitting units included in the second laser unit and the first laser receiving units included in the first laser unit may be arranged in a circular pattern, and the second control unit may control the second laser emitting units to emit laser light one by one in the order of the circular arrangement.

[0005] In any of the above communication systems, the first underwater optical communication device may have a first OCC unit that performs OCC (Optical Camera Communication) and a first acoustic communication unit that performs acoustic communication, and the second underwater optical communication device may have a second OCC unit that performs OCC and a second acoustic communication unit that performs acoustic communication. When the first underwater optical communication device is located within a range where OCC with the second underwater optical communication device is possible, the first control unit detects the second underwater optical communication device by OCC between the first OCC unit and the second OCC, establishes optical communication between the first optical communication unit and the second optical communication unit, controls a movement mechanism of the first underwater optical communication device so as to increase the distance between the first underwater optical communication device and the second underwater optical communication device, and when the OCC between the first OCC unit and the second OCC unit is disconnected, estimates the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the multiple first laser receiving units, and controls the movement mechanism of the first underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction.

[0006] In any of the communication systems, when the first underwater optical communication device is located within a range where OCC with the second underwater optical communication device is possible, the first control unit detects the second underwater optical communication device by OCC between the first OCC unit and the second OCC unit, establishes optical communication between the first optical communication unit and the second optical communication unit, controls a movement mechanism of the first underwater optical communication device so as to increase the distance between the first underwater optical communication device and the second underwater optical communication device, and when the OCC between the first OCC unit and the second OCC unit is disconnected, estimates the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the multiple first laser receiving units, controls the movement mechanism of the first underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and starts acoustic tracking of the second underwater optical communication device by acoustic communication between the first acoustic communication unit and the second acoustic communication unit while controlling the movement mechanism of the first underwater optical communication device so as to increase the distance between the first underwater optical communication device and the second underwater optical communication device.

[0007] In any of the communication systems, when the first underwater optical communication device is not located within a range where OCC is possible with the second underwater optical communication device, the first control unit may detect the second underwater optical communication device through acoustic communication between the first acoustic communication unit and the second acoustic communication unit, and based on the detection result, may perform a search for the second laser unit using the multiple first laser receiving units while controlling a movement mechanism of the first underwater optical communication device so that the distance between the first underwater optical communication device and the second underwater optical communication device decreases. When the first control unit detects the second laser unit by searching for the second laser unit using the multiple first laser receiving units, it may estimate the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the multiple first laser receiving units, control the movement mechanism of the first underwater optical communication unit so as to shorten the distance between the first underwater optical communication unit and the second underwater optical communication unit while aligning the first laser unit with the second laser unit based on the relative direction, and control the adjustment of the direction of optical communication of the first optical communication unit based on the light from the second optical antenna received by the first optical antenna.

[0008] In any of the above communication systems, the first laser unit may include a plurality of first laser irradiating units that irradiate laser light in the direction of optical communication of the first optical communication unit, and the second laser unit may include a plurality of second laser receiving units that receive laser light from the direction of optical communication of the second optical communication unit and are arranged in a manner similar to the arrangement of the plurality of first laser irradiating units, and the second control unit may detect the first laser unit based on the laser light received by at least any of the plurality of second laser receiving units, estimate the relative direction of the first laser unit based on the position of the second laser unit based on the time-series laser light reception status by the plurality of second laser receiving units, control the movement mechanism of the second underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and control the second optical communication device to adjust the direction of optical communication based on the light from the first optical antenna received by the second optical antenna. The plurality of first laser receiving units and the plurality of first laser emitting units may be alternately arranged in a circle, and the plurality of second laser receiving units and the plurality of second laser emitting units may be alternately arranged in a circle. The plurality of first laser receiving units may be circularly arranged along a first circle with a first radius, the plurality of first laser emitting units may be circularly arranged along a second circle with a second radius different from the first radius and whose center coincides with that of the first circle, the plurality of second laser receiving units may be circularly arranged along a third circle with the second radius, and the plurality of second laser emitting units may be circularly arranged along a fourth circle with the first radius and whose center coincides with that of the third circle.

[0009] According to one embodiment of the present invention, there is provided an underwater optical communication device that can move underwater. The underwater optical communication device may include a first optical communication unit including a first optical antenna. The underwater optical communication device may include a first laser unit including a plurality of first laser light receiving units that receive laser light from the optical communication direction of the first optical communication unit. The underwater optical communication device detects the second laser unit of another underwater optical communication device having a second optical communication unit including a second optical antenna, a second laser unit including a plurality of second laser emitting units arranged in the same manner as the plurality of first laser receiving units and emitting laser light in the direction of optical communication of the second optical communication unit, and a second control unit that controls the laser light to be emitted in sequence from the plurality of second laser emitting units based on the laser light received by at least one of the plurality of first laser receiving units, and estimates the relative direction of the second laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, and controls the movement mechanism of the underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and may be provided with a first control unit that controls to adjust the direction of optical communication of the first optical communication unit based on the light from the second optical antenna received by the first optical antenna.

[0010] According to one embodiment of the present invention, there is provided a control method, which may be executed by a first control unit of an underwater optical communication device that is movable underwater and includes a first optical communication unit including a first optical antenna, a first laser unit including a plurality of first laser light receiving units that receive laser light from the optical communication direction of the first optical communication unit, and a first control unit. The control method may include a step of detecting the second laser unit of another underwater optical communication device having a second optical communication unit including a second optical antenna, a second laser unit including a plurality of second laser emitting units arranged in the same manner as the plurality of first laser receiving units and emitting laser light in the direction of optical communication of the second optical communication unit, and a second control unit that controls the laser light to be emitted in sequence from the plurality of second laser emitting units, based on the laser light received by at least one of the plurality of first laser receiving units, estimating the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, controlling a movement mechanism of the underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and controlling the adjustment of the direction of optical communication of the first optical communication device based on the light from the second optical antenna received by the first optical antenna.

[0011] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0012] [Figure 1] 1 illustrates a schematic diagram of an example communication system 10. [Figure 2] 10 is an explanatory diagram for explaining alignment between the laser unit 120 and the laser unit 220. FIG. [Figure 3] 10 is an explanatory diagram for explaining alignment between the laser unit 120 and the laser unit 220. FIG. [Figure 4]10 is an explanatory diagram for explaining alignment between the laser unit 120 and the laser unit 220. FIG. [Figure 5] 10 is an explanatory diagram for explaining alignment between the laser unit 120 and the laser unit 220. FIG. [Figure 6] 10 is an explanatory diagram for explaining alignment between the laser unit 120 and the laser unit 220. FIG. [Figure 7] 1 is an explanatory diagram for explaining a sequence in which the communication system 10 establishes optical communication and extends the communication distance. [Figure 8] 10 is an explanatory diagram for explaining a sequence in which the communication system 10 resumes optical communication. FIG. [Figure 9] 1 illustrates a schematic diagram of an example communication system 10. [Figure 10] An example of a laser unit 120 and a laser unit 220 is shown schematically. [Figure 11] An example of a laser unit 120 and a laser unit 220 is shown schematically. [Figure 12] 1 illustrates a schematic diagram of an example of an underwater optical communicator. [Figure 13] 1 illustrates a schematic diagram of an example of an underwater optical communicator. [Figure 14] 1 illustrates a schematic diagram of an example of an underwater optical communicator. [Figure 15] 1 illustrates a schematic diagram of an example of an underwater optical communicator. [Figure 16] 1 illustrates a schematic diagram of an example of an underwater optical communicator. [Figure 17] 1 illustrates a schematic diagram of an example communication system 10. [Figure 18] 1 illustrates a schematic diagram of an example communication system 10. [Figure 19] An example of the hardware configuration of a computer 1200 that functions as the control unit 170 or the control unit 270 is shown in schematic form. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0014] The utilization of underwater vehicles, including remotely operated robots (ROVs) and autonomous underwater vehicles (AUVs), is increasing. Communication with underwater vehicles is primarily achieved via wired communication, which has operational limitations, or acoustic communication, which has limitations on communication speed. To overcome these limitations and improve the usability of underwater vehicles, long-distance, high-speed wireless communication that can be used underwater is required. A possible method for achieving this is to combine visible light laser communication with high-precision tracking technology. However, there is currently no tracking technology that can capture and track underwater vehicles moving freely over a wide area while aligning a laser optical axis to achieve stable optical communication. The communication system according to this embodiment contributes to solving these issues by providing optical tracking technology that combines, for example, coarse tracking, which captures the position of an underwater optical communication vehicle using multiple laser emitters and multiple laser receivers, and fine tracking, which aligns a laser optical axis using an optical antenna.

[0015] 1 schematically illustrates an example of a communication system 10 that performs underwater optical wireless communication. The communication system 10 includes an underwater optical communication device 100 and an underwater optical communication device 200 that are disposed underwater. The underwater optical communication device 100 may be an example of a first underwater optical communication device. The underwater optical communication device 200 may be an example of a second underwater optical communication device.

[0016] In this example, the underwater optical communication device 100 has the function of moving underwater by itself. In this example, the underwater optical communication device 200 does not have the function of moving underwater by itself. In the example shown in FIG. 1 , the underwater optical communication device 200 is fixed to a ship 40. The underwater optical communication device 200 may be fixed to any location other than the ship 40.

[0017] The underwater optical communication device 200 has an optical communication unit 210 including an optical antenna 212. The optical antenna 212 may be an example of a second optical antenna. The optical communication unit 210 may be an example of a second optical communication unit. The underwater optical communication device 200 has a laser unit 220. The laser unit 220 may be an example of a second laser unit. As shown in the lower right of FIG. 1 , the laser unit 220 includes a plurality of laser irradiation units 230. In the example shown in FIG. 1 , the laser unit 220 has eight laser irradiation units 230, but the number of laser irradiation units 230 is not limited to this. The number of laser irradiation units 230 may be less than eight. For example, the number of laser irradiation units 230 is 7, 6, 5, 4, or 3. The number of laser irradiation units 230 may be more than eight.

[0018] The multiple laser irradiation units 230 are arranged to form a certain shape. For example, the multiple laser irradiation units 230 may be arranged in a circular shape. Specifically, for example, if there are eight laser irradiation units 230, the eight may be arranged in a circular shape so that they are positioned at equal intervals on the circumference of a circle. Furthermore, for example, the multiple laser irradiation units 230 may be integrated. For example, the multiple laser irradiation units 230 may be integrated to form a ring shape as a whole, and laser light may be emitted from different positions on the circumference of the ring. In other words, the multiple laser irradiation units 230 may be a group of devices that can emit laser light from different positions, or may be a single device.

[0019] The laser irradiation unit 230 irradiates the laser light 22 in the direction of optical communication of the optical communication unit 210. The direction of optical communication of the optical communication unit 210 may be the orientation direction of optical communication of the optical communication unit 210. The direction of optical communication does not have to completely match the direction of optical communication. The laser irradiation unit 230 may irradiate the laser light 22 in a direction that completely matches the direction of optical communication of the optical communication unit 210. The laser irradiation unit 230 may irradiate the laser light 22 in a direction that is slightly deviated from the direction of optical communication of the optical communication unit 210. The irradiation direction of the laser light 22 of the laser irradiation unit 230 may be changeable.

[0020] The underwater optical communication device 200 has a control unit 270. The control unit 270 may be an example of a second control unit. The control unit 270 executes various controls in the underwater optical communication device 200. For example, the control unit 270 controls the irradiation of the laser light 22 by the multiple laser irradiation units 230. The control unit 270 may control the on / off of the irradiation of the laser light 22 by each of the multiple laser irradiation units 230. The control unit 270 may control the multiple laser irradiation units 230 to irradiate the laser light in order. For example, when the multiple laser irradiation units 230 are arranged in a circle, the control unit 270 may control the multiple laser irradiation units 230 to irradiate the laser light in the order of the circular arrangement.

[0021] The underwater optical communication device 100 has an optical communication unit 110 including an optical antenna 112. The optical antenna 112 may be an example of a first optical antenna. The optical communication unit 110 may be an example of a first optical communication unit. The underwater optical communication device 100 has a laser unit 120. The laser unit 120 may be an example of a first laser unit. As shown in the lower left of FIG. 1, the laser unit 120 includes a plurality of laser receiving units 150. The laser receiving units 150 may be an example of a first laser receiving unit. In the example shown in FIG. 1, the laser unit 120 has eight laser receiving units 150, but the number of laser receiving units 150 is not limited to this. The number of laser receiving units 150 may be less than eight. For example, the number of laser receiving units 150 is 7, 6, 5, 4, or 3. The number of laser receiving units 150 may be more than eight.

[0022] The multiple laser receiving units 150 are arranged to form a fixed shape. For example, the multiple laser receiving units 150 may be arranged in a circular shape. Specifically, for example, if there are eight laser receiving units 150, the eight may be arranged in a circular shape at equal intervals on the circumference of a circle. The multiple laser receiving units 150 may be integrated together. For example, the multiple laser receiving units 150 may be integrated together to form a ring shape as a whole, and laser light may be received at different positions on the circumference of the ring. In other words, the multiple laser receiving units 150 may be a group of devices that can receive laser light from different positions, or may be a single device.

[0023] The laser receiving unit 150 receives laser light from the direction of optical communication of the optical communication unit 110. The direction of optical communication of the optical communication unit 110 may be the orientation direction of optical communication of the optical communication unit 110. The laser receiving unit 150 may be configured to receive laser light 22 from a direction that completely matches the direction of optical communication of the optical communication unit 110. The laser receiving unit 150 may also be configured to receive laser light 22 from a direction that is slightly offset from the direction of optical communication of the optical communication unit 110. In the example shown in FIG. 1 , the laser receiving unit 150 receives laser light 22 irradiated from the laser irradiating unit 230.

[0024] The number of laser receiving sections 150 included in the laser unit 120 may be the same as the number of laser emitting sections 230 included in the laser unit 220. The arrangement of the multiple laser receiving sections 150 included in the laser unit 120 may be the same as the arrangement of the multiple laser emitting sections 230 included in the laser unit 220. The arrangement of the multiple laser receiving sections 150 included in the laser unit 120 may be the same as the arrangement of the multiple laser emitting sections 230 included in the laser unit 220. The arrangement of the multiple laser receiving sections 150 included in the laser unit 120 may be slightly shifted from the arrangement of the multiple laser emitting sections 230 included in the laser unit 220.

[0025] In this embodiment, unless otherwise specified, the number of laser receiving units and the number of laser irradiating units are eight will be described as an example, but the number of laser receiving units and the number of laser irradiating units are not limited to eight, as in the example shown in Figure 1.

[0026] The underwater optical communication device 100 has a control unit 170. The control unit 170 may be an example of a first control unit. The control unit 170 executes various controls in the underwater optical communication device 100. For example, the control unit 170 controls the detection of the laser unit 220. For example, the control unit 170 detects the laser unit 220 based on the laser light 22 received by at least one of the multiple laser light receiving units 150. As a specific example, when at least one of the multiple laser light receiving units 150 receives the laser light 22, the control unit 170 determines that the laser unit 220 is present in the light receiving direction.

[0027] For example, the control unit 170 estimates the relative direction of the laser unit 220 with respect to the position of the laser unit 120. For example, the control unit 170 estimates the relative direction of the laser unit 220 with respect to the position of the laser unit 120 based on the reception status of the laser beam 22 by the multiple laser receiving units 150. As a specific example, the control unit 170 may estimate the relative direction based on which of the multiple laser receiving units 150 has received the laser beam 22. For example, the control unit 170 estimates that the laser unit 220 is located in the direction of the laser receiving unit 150 that received the laser beam 22. The control unit 170 may estimate the relative direction based on the reception status of the laser beam 22 by the multiple laser receiving units 150 in chronological order. For example, the control unit 170 estimates the relative direction based on the chronological order in which the multiple laser receiving units 150 received the laser beam 22. For example, the control unit 170 estimates that the laser unit 220 is located in the direction of the laser receiving unit 150 that first received the laser beam 22. The control unit 170 may estimate the relative direction based on the cumulative received intensity of the laser beam 22 per unit time for each of the multiple laser receiving units 150. For example, the control unit 170 estimates that the laser unit 220 is located in the direction of the laser receiving unit 150 that has the greatest cumulative received intensity of the laser beam 22 per unit time.

[0028] The control unit 170 controls the movement mechanism 182 of the underwater optical communication device 100 to align the laser unit 120 and the laser unit 220 based on the estimated relative direction. As a result, the control unit 170 may adjust the positions of the laser unit 120 and the laser unit 220 to a range where light can be transmitted and received between the optical antenna 112 and the optical antenna 212 (sometimes referred to as coarse tracking). The movement mechanism 182 is a mechanism for moving the underwater optical communication device 100 underwater. Although a screw is illustrated as the movement mechanism 182 in FIG. 1, the movement mechanism 182 may be any mechanism as long as it can move the underwater optical communication device 100 underwater.

[0029] The control unit 170 controls the optical communication unit 110 to adjust the direction of optical communication based on the light received by the optical antenna 112 from the optical antenna 212. For example, the control unit 170 adjusts the optical path in the optical communication unit 210 so that the light received by the optical antenna 112 from the optical antenna 212 is positioned at the center of an optical receiver included in the optical communication unit 210. As a specific example, in the case where the optical communication unit 210 includes a two-dimensional CCD (Charge Coupled Device), an optical path adjustment mechanism, a beam splitter that splits the light received from the optical antenna 212 between the two-dimensional CCD and the adjustment mechanism, a four-segment photodiode, an optical receiver, and a plurality of beam splitters that split the light from the adjustment mechanism between the four-segment photodiode and the optical receiver, the control unit 170 first adjusts the light received by the optical antenna 112 so that it is positioned at the center of the two-dimensional CCD, and further adjusts the light that reaches the four-segment photodiode so that it is positioned at the center of the four-segment photodiode. The configuration of the optical communication unit 210 and the method of adjusting the optical path are not limited to these, and other configurations and adjustment methods may be adopted. Furthermore, for example, the control unit 170 controls the movement mechanism 182 of the underwater optical communication device 100 to finely adjust the position of the underwater optical communication device 100 so that the light from the optical antenna 212 received by the optical antenna 112 is positioned at the center of the optical receiver provided in the optical communication unit 210. As a result, the control unit 170 may finely adjust (sometimes called fine tracking) the direction of optical communication between the optical communication unit 210 and the optical communication unit 110. This makes it possible to align the laser optical axis while capturing and tracking the underwater optical communication device, thereby achieving stable optical communication.

[0030] The underwater optical communication device 200 may have an OCC unit 292 that performs OCC (Optical Camera Communication). The OCC unit 292 may be an example of a second OCC unit. The OCC unit 292 may have a light emitting device as a transmitter and a camera as a receiver. The light emitting device as a transmitter irradiates light in the direction of optical communication of the optical communication unit 210. The camera as a receiver captures light from the direction of optical communication of the optical communication unit 210. The OCC unit 292 may not have its own light emitting device, but may use a light emitting device included in the underwater optical communication device 200. For example, the OCC unit 292 uses at least one of the multiple laser irradiation units 230.

[0031] The underwater optical communication device 200 may have an acoustic communication unit 294 that performs acoustic communication. The acoustic communication unit 294 may be an example of a second acoustic communication unit. The acoustic communication unit 294 has a sound wave transmitter and a sound collector, and performs communication by transmitting sound waves containing information and collecting sound waves containing information.

[0032] The underwater optical communication device 100 may include an OCC unit 192 that performs OCC. The OCC unit 192 may be an example of a first OCC unit. The requirements for the light-emitting device used by the OCC unit 192 for OCC are the same as those for the OCC unit 292.

[0033] The underwater optical communication device 100 may have an acoustic communication unit 194 that performs acoustic communication. The acoustic communication unit 194 may be an example of a first acoustic communication unit. The acoustic communication unit 194 has a sound wave transmitter and a sound collector, and performs communication by transmitting sound waves containing information and collecting sound waves containing information.

[0034] The wavelength, phase, intensity, and divergence angle of the laser beam 22 emitted by the laser irradiation unit 230 are not particularly limited. The wavelength of the laser beam 22 may be selected so that the attenuation of the laser beam 22 in the liquid in which the communication system 10 is actually operated is small. For example, a sample of the liquid in which the communication system 10 is actually operated may be obtained, and an absorption spectrum may be obtained by measuring it with a spectrophotometer, and the wavelength band of the laser beam 22 may be selected from a wavelength band with small absorbance. This makes it possible to reduce the influence of attenuation of the laser beam 22 due to dissolved substances and dissipated substances in seawater, for example, when the communication system 10 is operated in a specific sea area. The wavelength of the laser beam 22 may be selected from visible light.

[0035] The wavelength of the laser light 22 may be selected from the range of 360 nm to 830 nm, for example. The divergence angle of the laser light 22 may be adjusted depending on the distance between the underwater optical communication device 100 and the underwater optical communication device 200. Specifically, when the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is large and the intensity of the laser light 22 received by the laser receiving unit 150 is relatively small, the divergence angle of the laser light 22 may be reduced to increase the intensity of the laser light 22. When the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is small and the intensity of the laser light 22 received by the laser receiving unit 150 is relatively large, the divergence angle of the laser light 22 may be increased to increase the range over which the underwater optical communication device 100 can receive the laser light 22. This allows the tracking distance and the searchable range to be adjusted in a balanced manner depending on the distance between the underwater optical communication device 100 and the underwater optical communication device 200. The spread angle of the laser light 22 may be adjusted by adjusting the type and focal length of the collimator lens of the laser irradiation unit 230 .

[0036] The wavelength, phase, and intensity of the laser light received by the laser receiving unit 150 are not particularly limited. The wavelength of the laser light received by the laser receiving unit 150 may be limited to a specific wavelength. For example, the laser receiving unit 150 may be filtered so as to receive only laser light within the same wavelength range as the laser light 22 emitted by the laser emitting unit 230 and not receive laser light within a wavelength range different from that of the laser light 22. This reduces the influence of light received by the laser receiving unit 150 other than the laser light 22 emitted from the laser emitting unit 230, thereby enabling the control unit 170 to more accurately detect the position of the laser unit 220. Furthermore, the wavelength of the laser light 22 emitted by the laser emitting unit 230 may be different from the wavelength of light used by the optical antenna 212 for optical communication. This reduces the influence of light emitted from the optical antenna 212 within the light received by the laser receiving unit 150, thereby enabling the control unit 170 to more accurately detect the position of the laser unit 220.

[0037] The irradiation period during which each of the multiple laser emitting units 230 emits the laser light 22 may be adjustable. Specifically, when the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is large and the intensity of the laser light 22 received by the laser receiving unit 150 is relatively small, the irradiation period of the laser light 22 may be lengthened to adjust the cumulative intensity per unit time of the laser light 22. This increases the probability that the underwater optical communication device 100 can capture the underwater optical communication device 200. When the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is small and the intensity of the laser light 22 received by the laser receiving unit 150 is relatively large, the irradiation period of the laser light 22 may be shortened to adjust the amount of movement of the underwater optical communication device 100 and the underwater optical communication device 200 due to tidal currents, etc., during the period when one laser emitting unit 230 is emitting the laser light 22. This makes it easier for the underwater optical communication device 100 to estimate the accurate position of the underwater optical communication device 200. In this way, a balanced adjustment can be made depending on the distance between the underwater optical communication device 100 and the underwater optical communication device 200, so that when the distance is large, priority is given to the probability of capture, and when the distance is small, priority is given to the accuracy of position estimation.

[0038] 2 to 6 are explanatory diagrams for explaining the alignment of the laser unit 120 and the laser unit 220. 2 to 6 schematically show the positional relationship between the laser unit 120 and the laser unit 220 when the underwater optical communication device 200 is viewed from the side where the underwater optical communication device 100 is located. 2 to 6 will be described using as an example a case where a plurality of laser emitting units 230 and a plurality of laser receiving units 150 are arranged in a circle. For convenience of explanation, parts of the underwater optical communication device 100 other than the laser unit 120 and parts of the underwater optical communication device 200 other than the laser unit 220 will be omitted.

[0039] In Figures 2 to 6, a small overlap between laser unit 120 and laser unit 220 indicates a low degree of alignment between the position of laser unit 120 and laser unit 220, and a large overlap between laser unit 120 and laser unit 220 indicates a high degree of alignment between laser unit 120 and laser unit 220.

[0040] In the example shown in Figures 2 to 6, the laser unit 120 includes multiple laser receiving sections, namely, laser receiving section 152, laser receiving section 154, laser receiving section 156, laser receiving section 158, laser receiving section 160, laser receiving section 162, laser receiving section 164, and laser receiving section 166.

[0041] In the example shown in Figures 2 to 6, the laser unit 220 includes multiple laser irradiation sections, namely, laser irradiation section 232, laser irradiation section 234, laser irradiation section 236, laser irradiation section 238, laser irradiation section 240, laser irradiation section 242, laser irradiation section 244, and laser irradiation section 246.

[0042] 2 represents a state in which the laser unit 120 does not detect the laser unit 220. In stage A, the laser emitting unit 232 emits laser light 22, but none of the multiple laser receiving units of the laser unit 120 receives the laser light 22. In this example, the laser light 22 is not a completely collimated light but has a divergence angle, and the irradiation range of the laser light 22 expands by the divergence angle. Therefore, the range of the circle indicating the irradiation range of the laser light 22 is wider than the range of the laser emitting unit 232.

[0043] After laser irradiation unit 232 irradiates laser beam 22, laser irradiation unit 234 irradiates laser beam 22. Thereafter, laser irradiation unit 236, laser irradiation unit 238, and laser irradiation unit 240 irradiate laser beam 22 in the order of clockwise circular arrangement. In any of these cases, none of the multiple laser receiving units of laser unit 120 receives laser beam 22.

[0044] Stage B in Fig. 2 shows a state in which the laser unit 120 detects the laser unit 220 for the first time and the first sequence starts. In stage B, the laser light 22 emitted by the laser irradiation unit 242 is received by the laser light receiving unit 158 ​​and the laser light receiving unit 156. In Figs. 2 to 6, the laser light receiving unit receiving the laser light 22 is indicated by dense diagonal lines. In this stage, the control unit 170 does not control the movement mechanism 182, and the underwater optical communication device 100 does not move.

[0045] Stage C in Fig. 2 shows the state immediately after stage B. In stage C, the laser beam 22 irradiated by the laser irradiating unit 244 is received by the laser receiving unit 156 and the laser receiving unit 154. Here, the laser receiving unit 158 ​​is outside the irradiation range of the laser beam 22, but has a history of receiving the laser beam 22. In Figs. 2 to 6, the laser receiving units that have a history of receiving the laser beam 22 within the same sequence are indicated by sparse diagonal lines.

[0046] 3 shows a state in which the order of irradiating laser beam 22 has been completed and laser irradiating unit 232 is again irradiating laser beam 22. Although laser irradiating unit 232 is irradiating laser beam 22, none of the multiple laser receiving units of laser unit 120 has received laser beam 22. Laser receiving unit 158, laser receiving unit 156, and laser receiving unit 154 have a history of receiving laser beam 22 during the first sequence.

[0047] After the laser irradiation unit 232 irradiates the laser beam 22, the laser irradiation units 236, 238, and 240 irradiate the laser beam 22 in the order of the circular arrangement, clockwise. In any of these cases, none of the multiple laser receiving units of the laser unit 120 receives the laser beam 22.

[0048] Stage E in Fig. 3 shows a state in which the laser unit 120 detects the laser unit 220 again, and a second sequence begins. The laser beam 22 emitted by the laser emitting unit 242 is received by the laser receiving unit 158 ​​and the laser receiving unit 156. In stage E, the control unit 170 estimates the position of the laser unit 220 based on the state of the laser beam 22 received by the multiple laser receiving units of the laser unit 120 during the first sequence. In stage E, the three laser receiving units, the laser receiving unit 158, the laser receiving unit 156, and the laser receiving unit 154, have a history of receiving the laser beam 22. The control unit 170 may estimate that the underwater optical communication device 100 is located in the relative direction of the vector 30 obtained by combining the vectors of the multiple laser receiving units that have the history of receiving the laser beam, and control the moving mechanism 182 to move the underwater optical communication device 100.

[0049] 3, in response to the movement of the underwater optical communication device 100 in stage E, the position of the laser unit 120 approaches the position of the laser unit 220. In stage F, the laser light 22 irradiated by the laser irradiating unit 244 is received by the laser receiving unit 156, the laser receiving unit 154, and the laser receiving unit 152.

[0050] 4 shows a state in which the order of irradiating laser beam 22 has gone through another cycle, and laser irradiating unit 232 is again irradiating laser beam 22. Although laser irradiating unit 232 is irradiating laser beam 22, none of the multiple laser receiving units of laser unit 120 has received laser beam 22. Laser receiving unit 158, laser receiving unit 156, laser receiving unit 154, and laser receiving unit 152 have a history of receiving laser beam 22.

[0051] Stage H in FIG. 4 shows a state in which the laser unit 120 detects the laser unit 220 again and the third sequence begins. The laser beam 22 emitted by the laser emitting unit 242 is received by the laser receiving units 158, 156, and 154. In stage H, the control unit 170 estimates the position of the laser unit 220 based on the state of the laser beam 22 received by the multiple laser receiving units 150 of the laser unit 120 during the second sequence. In stage H, the four laser receiving units, i.e., the laser receiving unit 158, 156, 154, and 152, have a history of receiving the laser beam 22. The control unit 170 may control the moving mechanism 182 to move the underwater optical communication device 100 in the direction of the vector 30 obtained by combining the vectors of the multiple laser receiving units that have a history of receiving the laser beam.

[0052] 4, the laser unit 120 is brought closer to the laser unit 220 due to the movement of the underwater optical communication device 100 in stage H. In stage I, the laser light 22 irradiated by the laser irradiating unit 244 is received by the laser receiving unit 160, the laser receiving unit 158, the laser receiving unit 156, the laser receiving unit 154, and the laser receiving unit 152.

[0053] 5 shows a state in which the order of irradiation of the laser beam 22 has gone through another cycle, and the laser irradiation unit 232 is again irradiating the laser beam 22. The laser receiving unit 154 and the laser receiving unit 156 receive the laser beam 22 irradiated by the laser irradiation unit 232.

[0054] Stage K in FIG. 5 shows a state in which the laser unit 120 detects the laser unit 220 again and the fourth sequence begins. The laser beam 22 emitted by the laser emitting unit 242 is received by the laser receiving unit 160, the laser receiving unit 158, and the laser receiving unit 156. In stage K, the control unit 170 estimates the position of the laser unit 220 based on the state of the laser beam 22 received by the plurality of laser receiving units 150 of the laser unit 120 during the third sequence. In stage K, five laser receiving units, namely the laser receiving unit 160, the laser receiving unit 158, the laser receiving unit 156, the laser receiving unit 154, and the laser receiving unit 152, have a history of receiving the laser beam 22. The control unit 170 may control the moving mechanism 182 to move the underwater optical communication device 100 in the direction of the vector 30 obtained by combining the vectors of the plurality of laser receiving units that have a history of receiving the laser beam.

[0055] 5, the laser unit 120 has come closer to the laser unit 220 due to the movement of the underwater optical communication device 100 in stage K. In stage L, the center of the circle of the laser unit 120 overlaps within the range of the circle of the laser unit 220. When the laser units 120 and 220 overlap to this extent, adjustment of the optical wireless communication between the optical antenna 112 and the optical antenna 212 can be started. In stage L, the laser light 22 irradiated by the laser irradiating unit 244 is received by the laser receiving unit 166, the laser receiving unit 164, the laser receiving unit 162, the laser receiving unit 160, the laser receiving unit 158, the laser receiving unit 156, the laser receiving unit 154, and the laser receiving unit 152.

[0056] 6 shows a state in which the order of irradiation of the laser beam 22 has gone through another cycle, and the laser irradiating unit 232 is again irradiating the laser beam 22. The laser receiving unit 152, the laser receiving unit 154, and the laser receiving unit 156 receive the laser beam 22 irradiated by the laser irradiating unit 232.

[0057] 6 shows a state in which laser unit 120 detects laser unit 220 again and the fifth sequence begins. Laser light 22 emitted by laser emitting unit 242 is received by laser receiving units 162, 160, 158, and 156. In stage N, control unit 170 estimates the position of laser unit 220 based on the state of laser light 22 received by the multiple laser receiving units 150 of laser unit 120 during the fourth sequence.

[0058] In stage N, all eight laser receiving units 150 included in laser unit 120 have a history of receiving laser beam 22. In this case, the direction in which laser unit 220 is located cannot be estimated solely based on the presence or absence of a history of receiving laser beam 22. Therefore, control unit 170 may estimate vector 30, for example, by further using the chronological order in which the multiple laser receiving units received laser beam 22. In the fourth sequence, the chronological order in which the multiple laser receiving units received laser beam 22 is as follows: first, in stage K, laser receiving units 160, 158, and 156 receive laser beam 22; next, in stage L, laser receiving units 166, 164, 160, 154, and 152 receive laser beam 22. The control unit 170 may estimate the vector 30 in the direction of the laser receiving unit that received the laser beam 22 earliest in the time series. As another example, the control unit 170 may estimate the vector 30 by further using the cumulative intensities of the laser beam 22 received by the multiple laser receiving units during the fourth sequence. The multiple laser receiving units are listed in descending order of cumulative intensities of the laser beam 22 received during the fourth sequence: laser receiving unit 156 receives five intensities, laser receiving unit 154 receives four intensities, laser receiving unit 158 ​​receives three intensities, laser receiving unit 152 and laser receiving unit 160 receive two intensities, and laser receiving unit 162, laser receiving unit 164, and laser receiving unit 166 receive one intensities. The control unit 170 may estimate the vector 30 in the direction of the laser receiving unit that received the laser beam 22 with the highest cumulative intensity during the fourth sequence, for example. In step N, the control unit 170 estimates a vector 30 in the direction of the laser receiving unit 156. In step N, the control unit 170 controls the movement mechanism 182 to move the underwater optical communication device 100 in the direction of the vector 30.

[0059] 6, the laser unit 120 has come closer to the laser unit 220 due to the movement of the underwater optical communication device 100 in stage N. In stage O, the laser unit 120 and the laser unit 220 are almost overlapped. In response to detecting this state, the control unit 170 may stop controlling the movement mechanism 182. The control unit 170 may continue to control the movement mechanism 182 regardless of detecting this state.

[0060] In the examples shown in FIGS. 2 to 6 , the control unit 270 causes the multiple laser emitting units to emit laser light 22 in the order of the circular arrangement. The control unit 270 may control the multiple laser emitting units to emit laser light one by one in the order of the circular arrangement. In this case, the multiple laser emitting units do not emit laser light 22 simultaneously, and only one laser emitting unit emits laser light 22 at a given timing. Therefore, the control unit 170 can identify which of the multiple laser emitting units 230 emitted the laser light 22 received by the laser receiving unit. Furthermore, compared to when multiple laser emitting units emit laser light 22 simultaneously, the number of patterns of the time series order in which the multiple laser receiving units 150 receive the laser light 22 increases. This allows the control unit 170 to more accurately estimate the direction in which the laser unit 220 is located.

[0061] Note that the control unit 270 may control the laser irradiation unit 234 in the circular arrangement to irradiate the laser beam 22 while the laser irradiation unit 232 in the circular arrangement continues to irradiate the laser beam 22, rather than irradiating the laser beam 22 one by one. For example, the control unit 270 may control the laser irradiation unit 234 to irradiate the laser beam 22 while the laser irradiation unit 232 continues to irradiate the laser beam 22. In this case, the multiple laser irradiation units irradiate the laser beam 22 simultaneously. Therefore, at a given moment, the irradiation range of the laser beam 22 irradiated by the laser unit 220 is wider than when the laser irradiation units irradiate the laser beam 22 one by one. Furthermore, the cumulative intensity of the laser beam 22 received by the multiple laser receiving units is greater than when the laser irradiation units irradiate the laser beam 22 one by one. Therefore, the probability that the laser light receiving unit 150 can receive the laser light 22 increases, particularly when the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is long and there is significant attenuation of the laser light 22. This allows the control unit 170 to detect the laser unit 220 with a higher probability.

[0062] 7 is an explanatory diagram illustrating a sequence in which the communication system 10 establishes optical communication and extends the communication distance. Stage A in FIG. 7 shows a state in which the underwater optical communication device 100 and the underwater optical communication device 200 are relatively close to each other and the underwater optical communication device 100 is located within a range in which OCC with the underwater optical communication device 200 is possible. In stage A, optical communication has not yet been established. In stage A, the control unit 170 detects the underwater optical communication device 200 by the OCC32 of the OCC unit 192 and the OCC unit 292.

[0063] The underwater optical communication device 100 and the underwater optical communication device 200 may have a reflecting material on the surface that receives the OCC light emitted by the other communication device. This allows, for example, when the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is relatively short, the underwater optical communication device 100 can estimate the position of the underwater optical communication device 200 and the distance from the underwater optical communication device 200 by irradiating light itself and receiving light reflected by the reflecting material of the underwater optical communication device 200. The reflecting material may be, for example, a corner cube reflector.

[0064] 7, the control unit 170 may adjust and establish optical communication 34 between the optical communication unit 110 and the optical communication unit 210 based on the position of the underwater optical communication device 200 detected by the OCC. In stage B, the control unit 170 controls the movement mechanism 182 of the underwater optical communication device 100 so that the distance between the underwater optical communication device 100 and the underwater optical communication device 200 increases.

[0065] 7 is a stage in which the distance between the underwater optical communication device 100 and the underwater optical communication device 200 increases, and the underwater optical communication device 100 is located outside the range in which OCC with the underwater optical communication device 200 is possible. In stage C, the OCC 32 between the OCC unit 192 and the OCC unit 292 is disconnected. When the OCC 32 between the OCC unit 192 and the OCC unit 292 is disconnected, the control unit 170 may perform tracking with the laser light 22 using the laser unit 120 and the laser unit 220.

[0066] 7 , the control unit 170 estimates the relative direction of the laser unit 220 with reference to the position of the laser unit 120 based on the time-series reception states of the laser beam 22 by the multiple laser receiving units 150, and controls the movement mechanism 182 of the underwater optical communication device 100 to align the laser unit 120 and the laser unit 220 based on the relative direction. Details of the control method are the same as those in the examples shown in FIGS. 2 to 6 . The control unit 170 controls the movement mechanism 182 of the underwater optical communication device 100 so as to increase the distance between the underwater optical communication device 100 and the underwater optical communication device 200, while performing tracking with the laser beam 22 using the laser unit 120 and the laser unit 220. In this way, by changing the means by which the underwater optical communication device 100 tracks the underwater optical communication device 200 depending on the distance between the underwater optical communication device 100 and the underwater optical communication device 200, the time of laser beam irradiation, which consumes a lot of power, can be shortened. In turn, it becomes possible to extend the time during which the underwater optical communication device 100 can navigate alongside the water.

[0067] 7, the underwater optical communication device 100 starts acoustic tracking of the underwater optical communication device 200 by acoustic communication 36 between the acoustic communication unit 194 and the acoustic communication unit 294, while controlling the movement mechanism 182 of the underwater optical communication device 100 so that the distance between the underwater optical communication device 100 and the underwater optical communication device 200 increases. As a result, even if the distance between the underwater optical communication device 100 and the underwater optical communication device 200 increases and tracking by the laser light 22 and optical communication 34 are cut off, as in stage F, acoustic tracking of the underwater optical communication device 200 by acoustic communication 36 is possible, and therefore the time required to restore optical communication 34 can be shortened compared to when the underwater optical communication device 100 completely loses the position of the underwater optical communication device 200.

[0068] FIG. 8 is an explanatory diagram for explaining a sequence in which the communication system 10 restores optical communication after tracking by the laser light 22 and optical communication 34 are cut off.

[0069] 8, the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is relatively large, and the tracking and optical communication 34 by the laser beam 22 are cut off. Because the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is relatively large, the underwater optical communication device 100 is not located within a range where OCC is possible with the underwater optical communication device 200. In stage A, the control unit 170 detects the underwater optical communication device 200 through acoustic communication 36 between the acoustic communication unit 194 and the acoustic communication unit 294, and controls the movement mechanism 182 of the underwater optical communication device 100 based on the detection result so that the distance between the underwater optical communication device 100 and the underwater optical communication device 200 decreases.

[0070] At stage B in FIG. 8 , the distance between the underwater optical communication device 100 and the underwater optical communication device 200 has become close enough to enable tracking using the laser light 22. At stage B, the control unit 270 may control the laser unit 120 to scan the laser light 22 in order to irradiate the laser light 22. For example, the laser light 22 may be scanned horizontally (sometimes referred to as raster scanning). For example, the laser light 22 may be scanned spirally (sometimes referred to as wobbling scanning). The scanning of the laser light 22 may be performed by a mechanism that tilts the entire laser unit 220. The scanning of the laser light 22 may be performed by a mechanism that changes the irradiation direction of the laser light 22 of each of the multiple laser irradiation units. For example, the entire laser irradiation unit may be mechanically driven, or the laser irradiation unit may be provided with a mirror that changes the irradiation direction of the laser light 22 by reflection. The control unit 170 executes a search for the laser unit 220 using a plurality of laser light receiving units 150 in order to receive the scanned laser light 22 emitted from the laser unit 220. This enables the underwater optical communication device 100 to track the underwater optical communication device 200 even when the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is large.

[0071] 8, the control unit 170 detects the laser unit 220 by searching for the laser unit 220 using the multiple laser receiving units 150. Stage C shows a state in which the control unit 270 has completed scanning of the laser light 22 after establishing tracking of the underwater optical communication device 200 by the laser light 22.

[0072] In stage D of Fig. 8, the control unit 170 estimates the relative direction of the laser unit 120 based on the position of the laser unit 120, based on the time-series reception states of the laser light 22 by the multiple laser receiving units 150, and aligns the laser unit 120 with the laser unit 220 based on the relative direction. Details of the alignment method are the same as those shown in Figs. 2 to 6. The control unit 170 controls the movement mechanism 182 of the underwater optical communication device 100 so as to shorten the distance between the underwater optical communication device 100 and the underwater optical communication device 200, and controls the optical communication unit to adjust the direction of optical communication based on the light from the optical antenna 212 received by the optical antenna 112. Then, the state shown in stage E of Fig. 8 is reached.

[0073] As shown in Figure 8, according to the communication system 10 of this embodiment, it is possible to establish optical communication between the underwater optical communication device 100 and the underwater optical communication device 200 even if the distance between the underwater optical communication device 100 and the underwater optical communication device 200 is large.

[0074] FIG. 9 schematically illustrates an example of the communication system 10. In the example illustrated in FIG. 9, differences from the example illustrated in FIG. 1 will be mainly described, and descriptions of common parts with the example illustrated in FIG. 1 will be omitted. In the example illustrated in FIG. 9, the laser unit 120 includes a plurality of laser emitting units 130 in addition to a plurality of laser receiving units 150. The laser emitting units 130 may be an example of a first laser emitting unit. The plurality of laser emitting units 130 may irradiate laser light in the direction of optical communication of the optical communication unit 110. The plurality of laser emitting units 130 may be arranged in a circle.

[0075] 9, the laser unit 220 includes a plurality of laser receiving units 250 in addition to a plurality of laser emitting units 230. The laser receiving units 250 may be an example of a second laser receiving unit. The laser receiving units 250 receive laser light from the direction of optical communication of the optical communication unit. The plurality of laser receiving units 250 may be arranged in a circular shape.

[0076] The number of laser emitting units 130 included in the laser unit 120 may be the same as the number of laser receiving units 250 included in the laser unit 220. The arrangement of the multiple laser emitting units 130 included in the laser unit 120 may be the same as the arrangement of the multiple laser receiving units 250 included in the laser unit 220. The arrangement of the multiple laser emitting units 130 included in the laser unit 120 may be the same as the arrangement of the multiple laser receiving units 250 included in the laser unit 220. The arrangement of the multiple laser emitting units 130 included in the laser unit 120 may be slightly shifted from the arrangement of the multiple laser receiving units 250 included in the laser unit 220.

[0077] 9, the control unit 270 detects the laser unit 120 based on the laser light received by at least one of the multiple laser receiving units 250, and estimates the relative direction of the laser unit 120 with reference to the position of the laser unit 220 based on the time-series laser light reception status by the multiple laser receiving units 250. In the example shown in FIG. 9, the underwater optical communication device 200 is not connected to the ship 40, and is movable underwater like the underwater optical communication device 100. The underwater optical communication device 200 may include a movement mechanism 282. The control unit 270 may control the movement mechanism 282 of the underwater optical communication device 200 to align the positions of the laser unit 120 and the laser unit 220 based on the estimated relative direction, and may also control the optical communication unit 210 to adjust the direction of optical communication based on the light from the optical antenna 112 received by the optical antenna 212.

[0078] In the example shown in Fig. 9, both the underwater optical communication device 100 and the underwater optical communication device 200 are movable underwater, have multiple laser emitting units and multiple laser receiving units, and track each other. This shortens the distance that the underwater optical communication device 100 must travel compared to the example shown in Fig. 1, in which only the underwater optical communication device 100 tracks the underwater optical communication device 200. Therefore, the time required for tracking can be reduced. Furthermore, even if a malfunction occurs in the laser emitting unit or laser receiving unit of either the underwater optical communication device 100 or the underwater optical communication device 200 during operation of the communication system 10, redundancy is provided in which tracking can be maintained by the tracking function of the other device.

[0079] 9, the plurality of laser receiving sections 150 and the plurality of laser emitting sections 130 of the laser unit 120 are alternately arranged in a circle. In the example shown in FIG. 9, the plurality of laser receiving sections 250 and the plurality of laser emitting sections 230 of the laser unit 220 are alternately arranged in a circle.

[0080] 10 and 11 are schematic diagrams showing other examples of the laser unit 120 and the laser unit 220. In the example shown in FIG. 10, the laser unit 120 has a plurality of laser receiving sections 150 each having a radius r a 10, the laser irradiation units 130 are arranged in a circle with a radius r a different radius r b The circular arrangement is along a circle 302 of radius r a may be an example of the first radius, and the radius r b may be an example of the second radius. Circle 301 may be an example of the first circle, and circle 302 may be an example of the second circle.

[0081] In the example shown in FIG. 11, the laser unit 220 has a plurality of laser receiving sections 250 with a radius r b 11, the plurality of laser irradiation units 230 are arranged in a circle along a circle 303 of radius r aThe circles 303 and 304 are arranged in a circular pattern along a circle 304. The circle 303 may be an example of a third circle, and the circle 304 may be an example of a fourth circle.

[0082] 12 to 16 schematically show another example of an underwater optical communication device. In Fig. 12 to 16, only the structure of the underwater optical communication device 100 is described, but the underwater optical communication device 200 may have a similar structure. For example, the underwater optical communication device 200 may have a structure in which the positions of the laser emitting unit 130 and the laser receiving unit 150 of the underwater optical communication device 100 are swapped.

[0083] 12 to 16, the diameter of the circle formed by the plurality of laser emitting units 130 and the plurality of laser receiving units 150 is increased to the extent that it does not hinder the underwater optical communication device 100 from moving underwater. In the examples shown in Fig. 12 to 16, the diameter of the circle formed by the plurality of laser emitting units 130 and the plurality of laser receiving units 150 is larger than in the examples shown in Fig. 1 and Fig. 9. In this way, by increasing the diameter of the circle formed by the plurality of laser emitting units 130 and the plurality of laser receiving units 150, it is possible to increase the tracking range.

[0084] 12 and 13, the diameter of the main body 180 of the underwater optical communication device 100 is the same as in the examples shown in Fig. 1 and 9, and only the diameter of the circle formed by the plurality of laser emitting units 130 and the plurality of laser receiving units 150 is increased. In the example shown in Fig. 12, the laser unit 120 is fixed to the main body 180 by a support unit 184. In the example shown in Fig. 13, a plurality of pairs of laser emitting units 130 and laser receiving units 150 are arranged in a circle, and each pair is fixed to the main body 180 by a support unit 184.

[0085] 14 to 16, the diameter of the main body 180 of the underwater optical communication device 100 is made larger than that of the examples shown in Fig. 1 and Fig. 9, thereby making larger the diameter of the circle formed by the plurality of laser emitting units 130 and the plurality of laser receiving units 150. In the examples shown in Fig. 14 to 16, a plurality of pairs of one laser emitting unit 130 and one laser receiving unit 150 are arranged in a circle along the main body 180.

[0086] In the example shown in FIG. 14, a plurality of pairs of laser emitting units 130 and laser receiving units 150 are arranged in a circle along the outer periphery of the main body 180. In the example shown in FIG.

[0087] In the example shown in FIG. 15, a plurality of pairs of laser emitting units 130 and laser receiving units 150 are arranged in a circle along the inner wall of the main body 180.

[0088] 16, a plurality of pairs of laser emitting units 130 and laser receiving units 150 are arranged in a circular pattern, with the laser emitting units 130 located on the outer shell side of the main body 180 and the laser receiving units 150 located on the inner shell side of the main body 180. The positions of the laser emitting units 130 and the laser receiving units 150 may be reversed, and the circular arrangement may be such that the laser receiving units 150 are located on the outer shell side of the main body 180 and the laser emitting units 130 are located on the inner shell side of the main body 180.

[0089] 17 and 18 schematically illustrate an example of the communication system 10. The following mainly describes the differences between the example shown in FIG. 9 and the example shown in FIG. 9, and omits a description of the common parts. In the example shown in FIG. 17 and 18, the optical communication unit 110 is disposed outside the laser unit 120, not inside the laser unit 120, and the optical communication unit 210 is disposed outside the laser unit 220, not inside the laser unit 220. This separates the optical axis of the laser light used for tracking using the laser unit 120 and the laser unit 220 from the optical axis of the light used for optical communication using the optical communication unit 110 and the optical communication unit 210, thereby preventing optical interference and cancellation. This results in more stable optical communication.

[0090] In the example shown in FIG. 17, the optical communication unit 110 is fixed to the main body unit 180 by an optical communication unit support unit 186 , and the optical communication unit 210 is fixed to the main body unit 280 by an optical communication unit support unit 286 .

[0091] 18, optical communication unit 110 is connected to main body unit 180 by optical communication unit connection cable 188, and can be moved underwater by optical communication unit movement mechanism 114. Similarly, in the example shown in Fig. 18, optical communication unit 210 is connected to main body unit 280 by optical communication unit connection cable 288, and can be moved underwater by optical communication unit movement mechanism 214.

[0092] Underwater optical communication devices require a large-capacity battery, making them difficult to miniaturize. Furthermore, they are significantly affected by ocean currents and inertia, resulting in slow response speeds for attitude control. In contrast, as shown in the example of Figure 18, by separating and controlling the main body and optical communication units of the underwater optical communication device, the optical axis of the optical communication can be controlled with good response speed. Furthermore, when the underwater optical communication device performs underwater work, the control of the device for work and the control of the device for optical communication are mutually exclusive, making it difficult to achieve both work and communication. As shown in the example of Figure 18, by separating and controlling the main body and optical communication units of the underwater optical communication device, it becomes easier to achieve both work and optical communication.

[0093] 19 schematically illustrates an example of the hardware configuration of a computer 1200 functioning as the control unit 170 or the control unit 270. A program installed on the computer 1200 can cause the computer 1200 to function as one or more "units" of an apparatus according to the present embodiment, or can cause the computer 1200 to perform operations associated with the apparatus according to the present embodiment or one or more "units," and / or can cause the computer 1200 to perform a process according to the present embodiment or steps of the process. Such a program can be executed by the CPU 1212 to cause the computer 1200 to perform specific operations associated with some or all of the blocks in the flowcharts and block diagrams described herein.

[0094] The computer 1200 according to this embodiment includes a CPU 1212, a RAM 1214, and a graphics controller 1216, which are interconnected by a host controller 1210. The computer 1200 also includes input / output units such as a communications interface 1222, a storage device 1224, a DVD drive, and an IC card drive, which are connected to the host controller 1210 via an input / output controller 1220. The DVD drive may be a DVD-ROM drive, a DVD-RAM drive, or the like. The storage device 1224 may be a hard disk drive, a solid-state drive, or the like. The computer 1200 also includes a ROM 1230 and legacy input / output units such as a keyboard, which are connected to the input / output controller 1220 via an input / output chip 1240.

[0095] The CPU 1212 operates according to programs stored in the ROM 1230 and the RAM 1214, thereby controlling each unit. The graphics controller 1216 acquires image data generated by the CPU 1212 into a frame buffer or the like provided in the RAM 1214 or into the graphics controller itself, and causes the image data to be displayed on the display device 1218.

[0096] The communication interface 1222 communicates with other electronic devices via a network. The storage device 1224 stores programs and data used by the CPU 1212 in the computer 1200. The DVD drive reads programs or data from a DVD-ROM or the like and provides them to the storage device 1224. The IC card drive reads programs and data from an IC card and / or writes programs and data to an IC card.

[0097] The ROM 1230 stores therein a boot program or the like that is executed by the computer 1200 upon activation, and / or programs that depend on the hardware of the computer 1200. The input / output chip 1240 may also connect various input / output units to the input / output controller 1220 via a USB port, a parallel port, a serial port, a keyboard port, a mouse port, etc.

[0098] The programs are provided by a computer-readable storage medium such as a DVD-ROM or an IC card. The programs are read from the computer-readable storage medium, installed in the storage device 1224, RAM 1214, or ROM 1230, which are also examples of computer-readable storage media, and executed by the CPU 1212. Information processing described in these programs is read by the computer 1200, and causes cooperation between the programs and the various types of hardware resources described above. An apparatus or method may be configured by implementing operations or processing of information in accordance with the use of the computer 1200.

[0099] For example, when communication is performed between the computer 1200 and an external device, the CPU 1212 may execute a communication program loaded into the RAM 1214 and instruct the communication interface 1222 to perform communication processing based on the processing described in the communication program. Under the control of the CPU 1212, the communication interface 1222 reads transmission data stored in a transmission buffer area provided in the RAM 1214, the storage device 1224, a DVD-ROM, or a recording medium such as an IC card, and transmits the read transmission data to the network, or writes reception data received from the network to a reception buffer area or the like provided on the recording medium.

[0100] Furthermore, the CPU 1212 may cause all or a necessary portion of a file or database stored in an external recording medium such as the storage device 1224, a DVD drive (DVD-ROM), an IC card, etc. to be read into the RAM 1214, and may perform various types of processing on the data on the RAM 1214. The CPU 1212 may then write back the processed data to the external recording medium.

[0101] Various types of information, such as various types of programs, data, tables, and databases, may be stored on the recording medium and may undergo information processing. The CPU 1212 may perform various types of processing on data read from the RAM 1214, including various types of operations, information processing, conditional judgment, conditional branching, unconditional branching, information search / replacement, etc., as described throughout this disclosure and specified by the instruction sequences of the programs, and write the results back to the RAM 1214. The CPU 1212 may also search for information in a file, database, etc. on the recording medium. For example, if multiple entries, each having an attribute value of a first attribute associated with an attribute value of a second attribute, are stored on the recording medium, the CPU 1212 may search for an entry whose attribute value of the first attribute matches a specified condition from among the multiple entries, read the attribute value of the second attribute stored in the entry, and thereby obtain the attribute value of the second attribute associated with the first attribute that satisfies a predetermined condition.

[0102] The above-described programs or software modules may be stored in a computer-readable storage medium on or near the computer 1200. A recording medium such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet can also be used as a computer-readable storage medium, thereby providing the programs to the computer 1200 via the network.

[0103] The blocks in the flowcharts and block diagrams in the present embodiments may represent stages of a process in which an operation is performed or "parts" of an apparatus responsible for performing the operation. Particular stages and "parts" may be implemented by dedicated circuitry, programmable circuitry provided with computer-readable instructions stored on a computer-readable storage medium, and / or a processor provided with computer-readable instructions stored on a computer-readable storage medium. The dedicated circuitry may include digital and / or analog hardware circuits, including integrated circuits (ICs) and / or discrete circuits. The programmable circuitry may include reconfigurable hardware circuits, such as field programmable gate arrays (FPGAs) and programmable logic arrays (PLAs), including AND, OR, XOR, NAND, NOR, and other logical operations, flip-flops, registers, and memory elements.

[0104] A computer-readable storage medium may include any tangible device capable of storing instructions that are executed by an appropriate device, such that a computer-readable storage medium having instructions stored thereon comprises an article of manufacture, including instructions that can be executed to create means for performing the operations specified in the flowcharts or block diagrams. Examples of computer-readable storage media may include electronic storage media, magnetic storage media, optical storage media, electromagnetic storage media, semiconductor storage media, etc. More specific examples of computer-readable storage media may include floppy disks, diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), electrically erasable programmable read-only memory (EEPROM), static random access memory (SRAM), compact disc read-only memory (CD-ROM), digital versatile disc (DVD), Blu-ray disc, memory stick, integrated circuit card, etc.

[0105] The computer readable instructions may include either assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk®, JAVA®, C++, etc., and conventional procedural programming languages ​​such as the “C” programming language or similar programming languages.

[0106] Computer-readable instructions may be provided to a general-purpose computer, a special-purpose computer, or another programmable data processing device, or a programmable circuit, either locally or via a local area network (LAN) or a wide area network (WAN) such as the Internet, so that the processor of the programmable data processing device, such as a computer, or the programmable circuit executes the computer-readable instructions to generate means for performing the operations specified in the flowcharts or block diagrams. Here, the computer may be a personal computer (PC), a tablet computer, a smartphone, a workstation, a server computer, a general-purpose computer, a special-purpose computer, or the like, or may be a computer system in which multiple computers are connected. Such a computer system in which multiple computers are connected is also called a distributed computing system, and is a broad definition of computers. In a distributed computing system, multiple computers collectively execute a program by each executing a portion of the program and passing data between the computers as needed during program execution.

[0107] Examples of processors include computer processors, central processing units, processing units, microprocessors, digital signal processors, controllers, microcontrollers, etc. A computer may have one processor or multiple processors. In a multiprocessor system with multiple processors, each processor executes a portion of a program and passes data between processors as needed during program execution, allowing the multiple processors to collectively execute a program. For example, in multitasking, each of the multiple processors may execute a portion of each task in small chunks by switching tasks at time slice intervals. In this case, which portion of a program each processor executes changes dynamically. Which portion of a program each of the multiple processors executes may also be statically determined by multiprocessor-aware programming.

[0108] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0109] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a later process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0110] 10 Communication system, 22 Laser light, 30 Vector, 32 OCC, 34 Optical communication, 36 Acoustic communication, 40 Ship, 100 Underwater optical communication body, 110 Optical communication unit, 112 Optical antenna, 114 Optical communication unit moving mechanism, 120 Laser unit, 130 Laser irradiation unit, 150 Laser receiving unit, 152 Laser receiving unit, 154 Laser receiving unit, 156 Laser receiving unit, 158 Laser receiving unit, 160 Laser receiving unit, 162 Laser receiving unit, 164 Laser receiving unit, 166 Laser receiving unit, 170 Control unit, 180 Main body, 182 Moving mechanism, 184 Support unit, 186 Optical communication unit support unit, 188 Optical communication unit connecting cable, 192 OCC unit, 194 Acoustic communication unit, 200 Underwater optical communication body, 210 Optical communication unit, 212 optical antenna, 214 optical communication unit moving mechanism, 220 laser unit, 230 laser irradiation unit, 232 laser irradiation unit, 234 laser irradiation unit, 236 laser irradiation unit, 238 laser irradiation unit, 240 laser irradiation unit, 242 laser irradiation unit, 244 laser irradiation unit, 246 laser irradiation unit, 250 laser receiving unit, 270 control unit, 280 main body unit, 282 moving mechanism, 286 optical communication unit support unit, 288 optical communication unit connection cable, 292 OCC unit, 294 acoustic communication unit, 301, 302, 303, 304 yen, 1200 computer, 1210 host controller, 1212 CPU, 1214 RAM, 1216 graphic controller, 1218 display device, 1220 input / output controller, 1222 communication interface, 1224 Storage device, 1230 ROM, 1240 I / O chips

Claims

1. A communication system for underwater optical wireless communication, a first underwater optical communication device that is movable underwater; A second underwater optical communication device Equipped with The second underwater optical communication device is a second optical communication unit including a second optical antenna; a second laser unit including a plurality of second laser irradiation units that irradiates laser light in the direction of optical communication of the second optical communication unit; a second control unit that controls the plurality of second laser irradiation units to irradiate laser light in order; and The first underwater optical communication device is a first optical communication unit including a first optical antenna; a first laser unit including a plurality of first laser receiving units arranged in the same manner as the plurality of second laser emitting units, the first laser receiving units receiving laser light from the optical communication direction of the first optical communication unit; a first control unit that detects the second laser unit based on the laser light received by at least one of the plurality of first laser receiving units, estimates a relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, controls a moving mechanism of the first underwater optical communication device to align the first laser unit with the second laser unit based on the relative direction, and controls to adjust the direction of optical communication of the first optical communication unit based on the light from the second optical antenna received by the first optical antenna; having Communication system.

2. the plurality of second laser irradiation units included in the second laser unit and the plurality of first laser receiving units included in the first laser unit are respectively arranged in a circular shape, The communication system according to claim 1 , wherein the second control unit controls the plurality of second laser irradiation units to irradiate the laser light one by one in the order of the circular arrangement.

3. The first underwater optical communication device is a first OCC unit that executes OCC (Optical Camera Communication); a first acoustic communication unit that performs acoustic communication; and The second underwater optical communication device is a second OCC unit that executes the OCC; a second acoustic communication unit that performs acoustic communication; 2. The communication system of claim 1, comprising:

4. When the first underwater optical communication device is located within a range where OCC is possible with the second underwater optical communication device, the first control unit detects the second underwater optical communication device by the OCC between the first OCC unit and the second OCC unit, establishes optical communication between the first optical communication unit and the second optical communication unit, and controls the movement mechanism of the first underwater optical communication device so that the distance between the first underwater optical communication device and the second underwater optical communication device increases. When the OCC between the first OCC unit and the second OCC unit is disconnected, the relative direction of the second laser unit is estimated based on the position of the first laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, and the first laser unit and the second laser unit are aligned based on the relative direction. The communication system described in claim 3, wherein the movement mechanism of the first underwater optical communication device is controlled to align the laser unit.

5. When the first underwater optical communication device is located within a range where OCC with the second underwater optical communication device is possible, the first control unit detects the second underwater optical communication device by OCC between the first OCC unit and the second OCC unit, establishes optical communication between the first optical communication unit and the second optical communication unit, controls the movement mechanism of the first underwater optical communication device so that the distance between the first underwater optical communication device and the second underwater optical communication device increases, and when the OCC between the first OCC unit and the second OCC unit is disconnected, detects the time-series laser light reception state by the plurality of first laser receiving units. The relative direction of the second laser unit based on the position of the first laser unit is estimated based on the situation, and the movement mechanism of the first underwater optical communication device is controlled to align the first laser unit and the second laser unit based on the relative direction, and the first acoustic communication unit and the second acoustic communication unit. While controlling the movement mechanism of the first underwater optical communication device so that the distance between the first underwater optical communication device and the second underwater optical communication device increases, acoustic tracking of the second underwater optical communication device is started by acoustic communication between the first acoustic communication unit and the second acoustic communication unit.

6. When the first underwater optical communication device is not located within a range where OCC is possible with the second underwater optical communication device, the first control unit detects the second underwater optical communication device through acoustic communication between the first acoustic communication unit and the second acoustic communication unit, and based on the detection result, the first control unit controls the movement mechanism of the first underwater optical communication device so that the distance between the first underwater optical communication device and the second underwater optical communication device decreases. The communication system according to claim 3, wherein the first control unit performs a search for the second laser unit using the plurality of first laser receiving units.

7. When the first control unit detects the second laser unit by searching for the second laser unit using the plurality of first laser receiving units, the first control unit estimates the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, and aligns the first laser unit and the second laser unit based on the relative direction. The communication system described in claim 6 controls the movement mechanism of the first underwater optical communication unit so as to shorten the distance between the first underwater optical communication unit and the second underwater optical communication unit, and controls to adjust the direction of optical communication of the first optical communication unit based on the light from the second optical antenna received by the first optical antenna.

8. the first laser unit includes a plurality of first laser irradiation units that irradiate laser light in a direction of optical communication of the first optical communication unit, the second laser unit includes a plurality of second laser receiving units that receive laser light from a direction of optical communication of the second optical communication unit and are arranged in the same manner as the arrangement of the plurality of first laser emitting units, The second control unit detects the first laser unit based on the laser light received by at least one of the plurality of second laser receiving units, and estimates the relative direction of the first laser unit based on the position of the second laser unit based on the time-series laser light reception status by the plurality of second laser receiving units. The second control unit controls the movement mechanism of the second underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and controls to adjust the direction of optical communication of the second optical communication unit based on the light from the first optical antenna received by the second optical antenna.

9. the plurality of first laser receiving units and the plurality of first laser emitting units are alternately arranged in a circle, The communication system according to claim 8 , wherein the plurality of second laser receiving sections and the plurality of second laser emitting sections are alternately arranged in a circle.

10. the plurality of first laser receiving units are circularly arranged along a first circle having a first radius, the plurality of first laser irradiation units are circularly arranged along a second circle whose center coincides with that of the first circle and whose second radius is different from the first radius, the plurality of second laser receiving units are circularly arranged along a third circle having the second radius, The communication system according to claim 8 , wherein the plurality of second laser irradiation units are circularly arranged along a fourth circle having the first radius and a center coincident with that of the third circle.

11. An underwater optical communication device that can move underwater, a first optical communication unit including a first optical antenna; a first laser unit including a plurality of first laser light receiving units that receive laser light from the optical communication direction of the first optical communication unit; and a second control unit that controls the laser beams to be emitted from the second laser emitting units in order based on the laser beam received by at least one of the plurality of first laser receiving units, the second laser unit of another underwater optical communication device having a second optical communication unit including a second optical antenna, a second laser unit including a plurality of second laser emitting units arranged in the same manner as the arrangement of the plurality of first laser receiving units and emitting laser beams in the direction of optical communication of the second optical communication unit, the second control unit that controls the laser beams to be emitted from the plurality of second laser emitting units in order, the second control unit that detects the second laser unit of another underwater optical communication device having a second optical communication unit including a second optical antenna, the second laser unit including a plurality of second laser emitting units arranged in the same manner as the arrangement of the plurality of first laser receiving units and emitting laser beams in the direction of optical communication of the second optical communication unit, the second control unit that estimates the relative direction of the second laser unit based on the time-series laser beam reception status by the plurality of first laser receiving units, the first control unit that controls the movement mechanism of the underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and the first control unit that controls the adjustment of the direction of optical communication of the first optical communication device based on the light from the second optical antenna received by the first optical antenna. An underwater optical communication device comprising:

12. A control method executed by the first control unit of an underwater optical communication device having a first optical communication unit that is movable underwater and includes a first optical antenna, a first laser unit that includes a plurality of first laser receiving units that receive laser light from the optical communication direction of the first optical communication unit, and a first control unit, Based on the laser light received by at least one of the plurality of first laser receiving units, a second optical communication unit including a second optical antenna, a second laser unit including a plurality of second laser emitting units arranged in the same manner as the arrangement of the plurality of first laser receiving units and irradiating laser light in the direction of optical communication of the second optical communication unit, and a second control unit that controls the laser light to be emitted in order from the plurality of second laser emitting units. Detecting the second laser unit of another underwater optical communication device, and estimating the relative direction of the second laser unit based on the position of the first laser unit based on the time-series laser light reception status by the plurality of first laser receiving units, and controlling the movement mechanism of the underwater optical communication device to align the first laser unit and the second laser unit based on the relative direction, and controlling to adjust the direction of optical communication of the first optical communication unit based on the light from the second optical antenna received by the first optical antenna. A control method comprising:

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