Determination device, underwater vehicle, determination method, and program

Abstract

To enable a plurality of underwater vehicles to disperse to a plurality of targets and move autonomously.SOLUTION: A determination device includes transmission and reception means for transmitting a sound wave toward a target to which an underwater vehicle is directed and receiving a sound wave reflected by the target, and determination means for determining whether to maintain the target or to change the target to another target based on comparison between a priority associated with the transmitted sound wave and a priority associated with the received sound wave.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a determination device, an underwater vehicle, a determination method, and a program. [Background technology]

[0002] Techniques have been proposed for using multiple underwater vehicles. For example, Patent Document 1 describes a method of calculating a score indicating the ease of communication between a surface vehicle and an underwater vehicle at a candidate position of a surface vehicle monitoring multiple underwater vehicles based on position information indicating the position of each of the multiple underwater vehicles, and determining the target position of the surface vehicle based on the calculated score and the tracking priority obtained for each underwater vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-032916 Summary of the Invention [Problem to be solved by the invention]

[0004] When there are multiple targets to which the underwater vehicle is directed, it is preferable that the multiple underwater vehicles are distributed among the multiple targets and move autonomously.

[0005] An example of an objective of the present disclosure is to provide a determination device, an underwater vehicle, a determination method, and a program that can solve the above-mentioned problems. [Means for solving the problem]

[0006] According to a first aspect of the present disclosure, the decision-making device includes a transmitting / receiving means for transmitting sound waves toward a target toward which the underwater vehicle is heading and receiving the sound waves reflected from the target, and a decision-making means for determining whether to maintain the target or change to another target based on a comparison between a priority associated with the transmitted sound waves and a priority associated with the received sound waves.

[0007] According to a second aspect of the present disclosure, the underwater vehicle comprises a transmitting / receiving means for transmitting sound waves toward a target toward which the underwater vehicle is heading and receiving the sound waves reflected at the target, a decision means for deciding whether to maintain the target or change to another target based on a comparison between the priority associated with the transmitted sound waves and the priority associated with the received sound waves, and a moving means for moving the underwater vehicle itself toward the set target.

[0008] According to a third aspect of the present disclosure, a decision-making method includes a computer controlling a transmitting / receiving means to transmit acoustic waves toward a target toward which an underwater vehicle is heading and receive acoustic waves reflected from the target, and determining whether to maintain the target or change to another target based on a comparison between a priority associated with the transmitted acoustic waves and a priority associated with the received acoustic waves.

[0009] According to a fourth aspect of the present disclosure, the program causes a computer to control a transmitting / receiving means to transmit sound waves toward a target toward which an underwater vehicle is heading and to receive the sound waves reflected at the target, and to determine whether to maintain the target or change to another target based on a comparison between a priority associated with the transmitted sound waves and a priority associated with the received sound waves. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, multiple underwater vehicles can be dispersed to multiple targets and move autonomously. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of the configuration of an underwater vehicle according to at least one embodiment. [Figure 2] 1A and 1B are diagrams illustrating examples of images of an underwater vehicle sailing according to at least one embodiment. [Figure 3] 1 is a diagram showing an example of an image in which multiple underwater vehicles according to at least one embodiment are dispersed among multiple target ships. FIG. [Figure 4] This is a diagram showing an example of an image in which a large number of underwater vehicles converge on one target ship. [Figure 5] FIG. 10 is a diagram illustrating an example of the difference in the length of the path that sound waves transmitted by a sonar of an underwater vehicle, reflected by a target vessel, and return to the sonar, depending on the size and relative angle of the target vessel, according to at least one embodiment. [Figure 6] FIG. 1 illustrates an example of sound waves transmitted by a sonar in accordance with at least one embodiment. [Figure 7] FIG. 1 illustrates an example of sound waves received by a sonar in accordance with at least one embodiment. [Figure 8] FIG. 2 is a diagram illustrating an example of a data structure of data indicating a combination of frequencies assigned to an underwater vehicle according to at least one embodiment. [Figure 9] FIG. 10 illustrates an example of transmitting coded acoustic waves when multiple underwater vehicles set the same vessel as a target vessel according to at least one embodiment. [Figure 10] 1A-1C illustrate examples of pulse trains in acoustic waves transmitted by an underwater vehicle according to at least one embodiment. [Figure 11] 1A-1C illustrate examples of pulse trains in acoustic waves transmitted by an underwater vehicle according to at least one embodiment. [Figure 12] FIG. 10 illustrates an example of reception of coded acoustic waves when multiple underwater vehicles have set the same vessel as a target vessel according to at least one embodiment. [Figure 13] FIG. 1 illustrates an example of a pulse in an acoustic wave in accordance with at least one embodiment. [Figure 14]FIG. 1 illustrates an example of a pulse in an acoustic wave in accordance with at least one embodiment. [Figure 15] FIG. 1 illustrates an example sonar configuration according to at least one embodiment. [Figure 16] FIG. 16 is a diagram illustrating an example of a signal flow in the configuration shown in FIG. [Figure 17] FIG. 10 is a diagram showing an example of a processing procedure in which a code discrimination processing unit according to at least one embodiment determines whether to maintain or change the target vessel. [Figure 18] 10 is a diagram showing an example of the relationship between the processing cycle in which a fast Fourier transform unit performs a fast Fourier transform according to at least one embodiment and the time width of a pulse of a received sound wave. FIG. [Figure 19] FIG. 1 is a diagram showing an example of a procedure for processing an underwater vehicle according to at least one embodiment to set a target and perform homing navigation. [Figure 20] FIG. 10 is a diagram illustrating an example of a processing procedure in which a sonar according to at least one embodiment checks the homing status of another underwater vehicle. [Figure 21] 1 is a diagram showing an example of an image in which multiple underwater vehicles according to at least one embodiment are dispersed among multiple target ships. FIG. [Figure 22] FIG. 1 is a diagram illustrating an example of a processing procedure for an underwater vehicle to perform homing navigation with a set target according to at least one embodiment. [Figure 23] FIG. 1 illustrates an example of a configuration of a determination device according to at least one embodiment. [Figure 24] 1 is a diagram illustrating an example of the configuration of an underwater vehicle according to at least one embodiment. [Figure 25] FIG. 10 is a diagram illustrating an example of a processing procedure in a determination method according to at least one embodiment. [Figure 26] FIG. 1 illustrates an example configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes embodiments of the present invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0013] First Embodiment 1 is a diagram showing an example of the configuration of an underwater vehicle according to at least one embodiment. In the configuration shown in Fig. 1, the underwater vehicle 10 includes a sonar 11, a homing navigation control unit 12, a payload area 13, a power source area 14, a prime mover 15, a steering control unit 16, a screw propeller 17, and a rudder 18. With respect to a part of the underwater vehicle 10, the underwater vehicle 10 that includes that part will also be referred to as the underwater vehicle 10 itself.

[0014] The underwater vehicle 10 moves autonomously underwater. In particular, when multiple underwater vehicles 10 move toward multiple targets, each underwater vehicle 10 determines a target and moves toward the determined target so that the multiple underwater vehicles 10 are dispersed and head toward the multiple targets. To this end, the underwater vehicle 10 transmits acoustic waves coded to indicate a priority to a target, receives the acoustic waves reflected by the target, detects the target setting status of other underwater vehicles 10 based on the received acoustic waves, and determines whether to maintain the target or change to another target based on the detection results. The movement of the underwater vehicle 10 under its own power is also referred to as the traveling of the underwater vehicle 10. The movement of the underwater vehicle 10 by homing is also referred to as the homing traveling of the underwater vehicle 10.

[0015] In the following, an example will be described in which the target toward which the underwater vehicle 10 is heading is a ship traveling on the water. The ship that is the target toward which the underwater vehicle 10 is heading is also referred to as the target ship. A candidate target toward which the underwater vehicle 10 is heading is also referred to as a target object or simply as a target. However, the target toward which the underwater vehicle 10 is heading is not limited to a specific one, and can be any one that can be homed to using sound waves. In the following, an example will be described in which multiple underwater vehicles 10 are launched from a mother ship. However, the situation at the start of navigation of the underwater vehicles 10 is not limited to a specific situation, and various situations in which multiple underwater vehicles 10 can move toward multiple targets are possible.

[0016] The sonar 11 transmits underwater acoustic waves and receives the underwater acoustic waves reflected by an object such as a ship. Based on the received acoustic waves, the sonar 11 then detects the direction and distance of the object relative to the propulsion direction of the underwater vehicle 10. The sonar 11 transmits directional acoustic waves that are coded to indicate priority to a target vessel selected from the target group, and receives underwater acoustic waves that are reflected by the target vessel. Based on the received acoustic waves, the sonar 11 then detects the target setting status of other underwater vehicles 10. The coded sound waves transmitted by the sonar 11 are also referred to as coded sound waves. The sonar 11 may transmit coded sound waves separately from sound waves for detecting targets.

[0017] The sonar 11 may be configured to detect the direction and distance of the target vessel based on the propulsion direction of the underwater vehicle 10 based on underwater acoustic waves reflected by the target vessel. Alternatively, the sonar 11 may use the direction and distance of the target vessel among the directions and distances of the detected target vessels for homing navigation. Alternatively, the sonar 11 may transmit underwater acoustic waves toward the target vessel and receive underwater acoustic waves reflected by the target vessel to detect the direction and distance of the target vessel, separately from detecting the target vessel and deciding whether to maintain or change the target.

[0018] The sonar 11 for detecting the target and the sonar 11 for detecting the target setting status of the other underwater vehicle 10 may be configured as the same sonar, or may be configured as separate sonars.

[0019] The homing sailing control unit 12 selects a target from among the objects detected by the sonar 11. Furthermore, the homing navigation control unit 12 determines whether to maintain the target or change to another target based on the target setting status of the other underwater vehicle 10 detected by the sonar 11. The homing sailing control unit 12 also calculates a rudder angle for homing sailing to approach the target ship based on the direction and distance of the target ship detected by the sonar 11, and outputs a rudder angle signal to the steering control unit 16. The output of the rudder angle signal by the homing sailing control unit 12 can be considered as operating the rudder 18. Furthermore, the homing navigation control unit 12 may control the speed of the underwater vehicle 10 by controlling the motor 15 .

[0020] The payload area 13 is a storage area for items transported by the underwater vehicle 10. Items transported by the underwater vehicle 10 are also referred to as payloads. The payload is not limited to a specific item, and can be a variety of items depending on the type and use of the underwater vehicle 10.

[0021] The power source area 14 is an area for storing a power source for propelling the underwater vehicle 10. The power source stored in the power source area 14 can be various types of power sources depending on the type of prime mover 15. For example, if the prime mover 15 is an engine, the power source area 14 stores fuel for the engine. Alternatively, if the prime mover 15 is a motor (electric motor), the power source area 14 stores batteries.

[0022] The prime mover 15 converts the energy supplied by the power source into power for propelling the underwater vehicle 10. The prime mover 15 uses the obtained power to rotate the screw propeller 17, thereby propelling the underwater vehicle 10. The prime mover 15 is not limited to a specific type of prime mover. For example, the prime mover 15 may be configured using an engine or a motor. When the prime mover 15 is configured using an engine, the prime mover 15 may further be configured to include a generator for supplying power used by the underwater vehicle 10, such as power used by the sonar 11, the homing navigation control unit 12, and the steering control unit 16.

[0023] The steering control unit 16 operates the rudder 18 in accordance with the rudder angle signal output from the homing sailing control unit 12 .

[0024] The screw propeller 17 is connected to a rotary shaft rotated by the prime mover 15, and is rotationally driven by the rotation of the prime mover 15. The screw propeller 17 generates thrust for propelling the underwater vehicle 10 as it rotates. The screw propeller 17 may be configured using a contra-rotating propeller, which can avoid or reduce the rotation of the underwater vehicle 10 in the opposite direction to the screw propeller 17 due to the reaction of the rotation of the screw propeller 17.

[0025] The rudder 18 is a rudder for controlling the traveling direction of the underwater vehicle 10. The steering control unit 16 operating the rudder 18 can be considered to be controlling the traveling direction of the underwater vehicle 10. The rudder 18 may be configured to include a horizontal rudder and a vertical rudder, and may be capable of adjusting the direction of travel of the underwater vehicle 10 in the left-right and up-down directions.

[0026] 2 is a diagram showing an example of an image of the underwater vehicle 10 sailing. In the example of FIG. 2, a plurality of underwater vehicles 10 are launched from a mother ship 30 and sailing toward a target ship 40. The plurality of underwater vehicles 10 will also be referred to as a group of underwater vehicles 20. The plurality of target vessels 40 will also be referred to as a group of target vessels 50.

[0027] The mother ship 30 can be any of a variety of vessels capable of launching multiple underwater vehicles 10. For example, it may be a vessel capable of submerging underwater, but is not limited to this. Furthermore, as described above, the situation at the start of navigation of the underwater vehicle 10 is not limited to the situation where it is launched from the mother ship. The target vessel group 50 may be a group of target vessels 40 sailing in a convoy.

[0028] 3 is a diagram showing an example of an image in which multiple underwater vehicles 10 are dispersed and sailing toward multiple target ships 40. FIG. 3 shows an example in which the same number of underwater vehicles 10 as the number of target ships 40 are launched from the mother ship 30, and one underwater vehicle 10 sails toward one target ship 40.

[0029] 4 is a diagram showing an example of an image in which a large number of underwater vehicles 10 converge on one target ship 40. In the example of FIG. 4, all of the underwater vehicles 10 launched from the mother ship 30 are traveling toward the one target ship 40 that is closest to the mother ship 30. The homing navigation control unit 12 of the underwater vehicle 10 detects the target setting status of other underwater vehicles 10 using sound waves coded to indicate priority, in order to prevent multiple underwater vehicles 10 from concentrating on sailing toward one target vessel 40 as in the example of Figure 4. If an underwater vehicle 10 with a higher priority than the underwater vehicle 10 itself has set the same vessel as its own target vessel 40 as its target vessel 40, the homing navigation control unit 12 changes the underwater vehicle 10's own target vessel 40 to the other vessel.

[0030] In the first embodiment, an example will be described in which one underwater vehicle 10 sails toward one target ship 40. In the second embodiment, an example will be described in which two underwater vehicles 10 sail toward one target ship 40.

[0031] Figure 5 is a diagram showing an example of the difference in the length of the path that the sound waves transmitted by the sonar 11 of the underwater vehicle 10 take to reflect off the target ship 40 and return to the sonar 11, depending on the size and relative angle of the target ship 40. 5, point P11 indicates the end of the target ship 40 in the longitudinal direction that is closer to the underwater vehicle 10. Point P12 indicates the end of the target ship 40 in the longitudinal direction that is farther from the underwater vehicle 10.

[0032] The line L11 is a line that is oriented in the traveling direction of the sound wave transmitted by the sonar 11 and includes the point P11. The line L11 indicates the path of the sound wave when the sound wave transmitted by the sonar 11 is reflected at the point P11. The line L12 is a line that is oriented in the traveling direction of the sound wave transmitted by the sonar 11 and includes the point P12. The line L12 indicates the path of the sound wave when the sound wave transmitted by the sonar 11 is reflected at the point P12. Line L13 is a line that is perpendicular to the traveling direction of the sound wave transmitted by sonar 11 and includes point P11. Line L13 indicates the arrival position of the sound wave at the time when the sound wave traveling along the path of line L11 reaches point P11.

[0033] The angle θ is the angle between the direction of travel of the sound waves transmitted by the sonar 11 and the longitudinal direction of the target ship 40. The distance D11 is the distance between the point P11 and the point P12. The distance D11 indicates the overall length of the target vessel 40. Distance D12 is the distance between point P12 and the intersection of line L12 and line L13.

[0034] When the sound waves transmitted by the sonar 11 travel along the path of line L11, the path length when traveling along the path of line L12 is longer by a distance D12 on both the outbound and inbound routes than when traveling along the path of line L12. For example, if the distance D11 is 100 meters (m) and the angle θ is 45 degrees, the distance D12 can be calculated as 100×cos45°≈71 [meters]. Because the sound waves transmitted by the sonar 11 reflect off the target ship 40 and return to the sonar 11 in different lengths, the sonar 11 receives sound waves that have been stretched in the time direction.

[0035] Fig. 6 is a diagram showing an example of sound waves transmitted by the sonar 11. The horizontal axis of the graph in Fig. 6 represents time, and the vertical axis represents the level (intensity) of the sound waves. In the example of Figure 6, the sonar 11 transmits a pulse of sound waves with a pulse width of time T11, for example, time T11 is 1 millisecond.

[0036] Fig. 7 is a diagram showing an example of sound waves received by the sonar 11. Fig. 7 shows an example in which the sonar 11 receives sound waves that are the sound waves in the example of Fig. 6 that have been reflected off the target ship 40 and returned. The horizontal axis of the graph in Fig. 7 represents time, and the vertical axis represents the level (intensity) of the sound waves. Time T21 indicates the same time as time T11, which is the pulse width of the transmitted sound wave. Time T22 indicates the time when the sound wave received by the sonar 11 is extended from the transmitted sound wave. In the example of Fig. 7, the sonar 11 receives a pulse with a pulse width of time T21 + T22. If the speed of underwater sound waves is 1500 meters per second and the distance D12 in the example of Figure 5 is 71 meters, the time T22 can be calculated as 71 ÷ 1500 ≒ 0.047 [seconds] = 47 [milliseconds].

[0037] For example, the sonar 11 transmits a sound pulse with a pulse width of 1 millisecond and receives a sound pulse with a pulse width of 47 milliseconds, so the received sound wave is significantly stretched in the time direction compared to the transmitted sound wave from the sonar 11. Moreover, the length of time that the received sound wave is stretched compared to the transmitted sound wave varies depending on conditions such as the overall length of the target ship 40 and the angle between the traveling direction of the sound wave and the longitudinal direction of the target ship 40.

[0038] Therefore, if the sonar 11 transmits sound waves coded using a pulse width or a pulse train (presence or absence of a pulse), or a combination of these, it may not be possible to read the code from the received sound waves and therefore not be able to determine the priority. Therefore, the sonar 11 transmits sound waves coded using a combination of frequencies, allowing the sonar 11 to read the code from the received sound waves by detecting the frequencies contained in the received sound waves.

[0039] The following describes an example in which the sonar 11 transmits a pulse train consisting of a combination of pulses with different frequencies. In this case, the code can be indicated by how many pulses are transmitted from a predetermined number of frequencies (i.e., which combination of frequencies is selected from a predetermined number of frequencies to transmit).

[0040] In the following, an example will be described in which six frequencies, from frequency A to frequency F, are predetermined, and a code based on a combination of one or more of the six frequencies is assigned to each underwater vehicle 10. The code based on the combination of frequencies indicates the priority of each underwater vehicle 10. The code assigned to each underwater vehicle 10 is also referred to as a unique code. The priority indicated for each underwater vehicle 10 is also referred to as a homing priority.

[0041] FIG. 8 is a diagram showing an example of the data structure of data indicating the combination of frequencies assigned to the underwater vehicle 10. As shown in FIG. In the example of Fig. 8, A to F each represent a predetermined frequency. For example, A may represent 70 kHz, B may represent 72 kHz, C may represent 74 kHz, D may represent 76 kHz, E may represent 78 kHz, and F may represent 80 kHz.

[0042] As shown in the example of Figure 8, there are 63 combinations of selecting one or more frequencies from six frequencies, and these 63 combinations correspond to numbers from 1 to 63. Each of these 63 combinations corresponds to an example of a unique code. Furthermore, the number associated with the unique code may be used as a priority of the underwater vehicle 10, with a smaller number indicating a higher priority. Additionally, the "transmission order" indicates the order in which the sonar 11 transmits pulses of each frequency. In the example of Fig. 8, the sonar 11 transmits sound waves of pulse trains of frequencies A, B, C, D, E, and F in this order, or portions thereof.

[0043] For example, the homing sailing control unit 12 may store data showing the correspondence between codes and priorities, as illustrated in Figure 8, and convert the codes read by the sonar 11 from the received sound waves into priorities.

[0044] However, the correspondence between the combination of frequencies and the numbers is not limited to a specific one. For example, numbers from 1 to 63 may be expressed as six-digit binary numbers, with a frequency assigned to each digit. Then, for each digit, it may be specified that transmitting a pulse of the assigned frequency represents the value of that digit, "1," and not transmitting that pulse represents the value of that digit, "0." In this case, the homing sailing control unit 12 may not store data indicating the correspondence between codes and priorities, but may calculate numbers based on whether or not each frequency is included in the received sound waves. It may also be determined that the larger the number, the higher the priority.

[0045] Fig. 9 is a diagram showing an example of the transmission of coded sound waves when multiple underwater vehicles 10 set the same ship as the target ship 40. Fig. 9 shows an example when two underwater vehicles 10 set the same ship as the target ship 40. In the examples of Figs. 9 to 14, the two underwater vehicles 10 are given the reference symbols 10a and 10b to distinguish between these two underwater vehicles 10.

[0046] The sound wave 61a is an encoded sound wave transmitted by the underwater vehicle 10a. The acoustic wave 61b is an encoded acoustic wave transmitted by the underwater vehicle 10b. The underwater vehicles 10 a and 10 b transmit coded acoustic waves toward the same target vessel 40 .

[0047] Fig. 10 is a diagram showing an example of a pulse train in a sound wave 61a transmitted by the underwater vehicle 10a. The horizontal axis of the graph in Fig. 10 represents time, and the vertical axis represents the level (intensity) of the sound wave. The sound wave 61a includes a pulse U11. The frequency of the pulse U11 is assumed to be A. Referring to Fig. 8, the sound wave 61a indicates that the underwater vehicle 10a has the first priority.

[0048] Fig. 11 is a diagram showing an example of a pulse train in a sound wave 61b transmitted by the underwater vehicle 10b. The horizontal axis of the graph in Fig. 11 represents time, and the vertical axis represents the level (intensity) of the sound wave. The acoustic wave 61b includes pulses U21, U22, U23, U24, U25, and U26. The frequency of the pulse U21 is A, the frequency of the pulse U22 is B, the frequency of the pulse U23 is C, the frequency of the pulse U24 is D, the frequency of the pulse U25 is E, and the frequency of the pulse U26 is F. Referring to Fig. 8, the acoustic wave 61b indicates that the underwater vehicle 10b has the sixth priority. The unique code of the underwater vehicle 10a and the unique code of the underwater vehicle 10b indicate that the underwater vehicle 10a has a higher priority than the underwater vehicle 10b.

[0049] 12 is a diagram showing an example of reception of encoded sound waves when multiple underwater vehicles 10 set the same ship as the target ship 40. Fig. 12 shows an example of the case where the underwater vehicles 10a and 10b in Fig. 9 receive sound waves that have echoed off the target ship 40. The sound wave 62a is a sound wave that is the sound wave 61a transmitted by the underwater vehicle 10a and reflected by the target ship 40. The sound wave 62b is a sound wave that is the sound wave 61b transmitted by the underwater vehicle 10b and reflected by the target ship 40. Both underwater vehicles 10a and 10b receive sound waves 62a and 62b.

[0050] Fig. 13 is a diagram showing an example of a pulse in a sound wave 62a. The horizontal axis of the graph in Fig. 13 represents time, and the vertical axis represents the level (intensity) of the sound wave. The sound wave 62a includes a pulse U31. The pulse U31 is a pulse obtained by extending the pulse U11 of the sound wave 61a in the time direction. The frequency of the pulse U31 is A, which is the same as the frequency of the pulse U11.

[0051] Fig. 14 is a diagram showing an example of a pulse in the sound wave 62b. The horizontal axis of the graph in Fig. 14 represents time, and the vertical axis represents the level (intensity) of the sound wave. The sound wave 62b includes a pulse U41. The pulse U41 is a pulse in which pulses U21 to U26 of the sound wave 61b are extended in the time direction and overlap in time. The frequency of the pulse U41 is a frequency in which frequencies A to F of the pulses U21 to U26 are overlapped. In other words, the pulse U41 includes frequency components from frequencies A to F.

[0052] The underwater vehicle 10a receives the sound wave 62b, reads the priority, and detects that the underwater vehicle 10b, which has a lower priority than the underwater vehicle 10a itself, has set the same vessel as the target vessel 40 of the underwater vehicle 10a itself as its target vessel 40. As a result, the underwater vehicle 10a maintains the target vessel 40. The underwater vehicle 10b receives the sound wave 62a, reads the priority, and detects that the underwater vehicle 10a, which has a higher priority than the underwater vehicle 10b itself, has set the same vessel as the target vessel 40 of the underwater vehicle 10b itself as its target vessel 40. As a result, the underwater vehicle 10b changes the target vessel 40 to another vessel. In this way, the underwater vehicles 10a and 10b can be directed towards different ships.

[0053] The priority may be assigned to each underwater vehicle 10 so that the earlier an underwater vehicle 10 approaches the group of target ships 50, the higher the priority. For example, the earlier an underwater vehicle 10 is launched from the mother ship 30, the higher the priority.

[0054] This is expected to cause the underwater vehicle 10 to determine the target vessel 40 in descending order of priority. By having the underwater vehicle 10 determine the target vessel 40 in descending order of priority, it is expected that an underwater vehicle 10 that has already determined a target vessel 40 can avoid changing the target vessel 40 because an underwater vehicle 10 with a higher priority has set the same vessel as its own target vessel 40 as the target vessel 40. In this regard, it is expected that by assigning priorities so that the underwater vehicle 10 that approaches the target ship group 50 earlier has a higher priority, it will be possible to efficiently distribute multiple underwater vehicles 10 among multiple target ships 40.

[0055] Furthermore, if the underwater vehicle 10 receives coded sound waves transmitted by multiple underwater vehicles 10 that have echoed off the target ship 40 and overlap in time, it is possible that the priority of each underwater vehicle 10 will not be able to be accurately detected. For example, if the underwater vehicle 10b receives sound waves in which sound waves 62a and 62b overlap in time, it will receive sound waves with frequencies A to F overlapped together. In this case, it is conceivable that the underwater vehicle 10b will not be able to read the unique code of the underwater vehicle 10a from the received sound waves, and therefore will not be able to detect the priority of the underwater vehicle 10a.

[0056] Therefore, it is possible to transmit coded sound waves at different times for each underwater vehicle 10, so that the underwater vehicle 10 can receive sound waves that are reflected by the target ship 40 after sound waves transmitted by one underwater vehicle 10 are transmitted. For example, the timing of transmitting the coded sound waves may be determined for each underwater vehicle 10 so that the higher the priority of the underwater vehicle 10, the earlier the coded sound waves are transmitted. In this case, the underwater vehicle 10 detects the priority from the sound wave received earliest and compares it with its own priority, thereby determining whether an underwater vehicle 10 with a higher priority than the underwater vehicle 10 itself has set the same ship as the target ship 40 as the target ship 40 of the underwater vehicle 10 itself.

[0057] Alternatively, the underwater vehicle 10 may determine whether or not a plurality of sound waves are overlapping in time based on the level (signal strength) of each frequency component of the received sound waves. For example, when the underwater vehicle 10b receives sound waves in which sound waves 62a and 62b overlap in time, it is conceivable that the level of the frequency A component will be higher than the levels of the other components among the frequency components A to F. As a result, the underwater vehicle 10b may determine that the sound wave of frequency A is included in the received sound waves.

[0058] Fig. 15 is a diagram showing an example of the configuration of the sonar 11. In the configuration shown in Fig. 15, the sonar 11 includes a transmission waveform generating section 101, a digital-to-analog (D / A) converter 102, band pass filters (BPF) 103 and 108, a power amplifier 104, a transmission / reception switching circuit 105, an electrostrictive vibrator 106, a preamplifier 107, an analog-to-digital (A / D) converter 109, a fast Fourier transformation (FFT) section 110, a directivity synthesis section 111, and a code discrimination processing section 112.

[0059] 15 shows a configuration for generating and transmitting unique code sound waves and receiving sound waves to detect the unique code by the sonar 11. The configuration shown in FIG. 15 or a part thereof may also be used for the sonar 11 to perform the function of detecting an object such as a ship.

[0060] 15, a plurality of electrostrictive transducers 106 are arranged in an array so as to impart directionality to the transmission and reception of sound waves by the sonar 11. The sonar 11 includes, for each electrostrictive transducer 106, a transmission waveform generating unit 101, a digital-to-analog converter 102, bandpass filters 103 and 108, a power amplifier 104, a transmission / reception switching circuit 105, the electrostrictive transducer 106, a preamplifier 107, an analog-to-digital converter 109, and a fast Fourier transform unit 110.

[0061] FIG. 16 is a diagram showing an example of a signal flow in the configuration shown in FIG. 16, the homing navigation control unit 12 outputs a unique code to the transmission waveform generation unit 101 and the code discrimination processing unit 112. As described above, the unique code is determined for each underwater vehicle 10 and indicates the priority of the underwater vehicle 10. The transmission waveform generation unit 101 generates a digital signal of the transmission waveform based on the unique code and outputs it to the digital-to-analog converter 102. At this time, the transmission waveform generation unit 101 adjusts the phase of the digital signal of the transmission waveform so as to impart directionality to the sound waves transmitted by the sonar 11.

[0062] The digital-to-analog converter 102 converts the digital signal of the transmission waveform output by the transmission waveform generating section 101 into an analog signal. The digital-to-analog converter 102 outputs the obtained analog signal to the band-pass filter 103.

[0063] Bandpass filter 103 removes unnecessary frequency components so as to smooth the waveform of the analog signal output by digital-to-analog converter 102. Bandpass filter 103 outputs the signal from which the unnecessary frequency components have been removed to power amplifier 104.

[0064] Power amplifier 104 is configured using a power amplifier and amplifies the analog signal output by bandpass filter 103. Specifically, power amplifier 104 increases the voltage amplitude of the analog signal output by bandpass filter 103. Bandpass filter 103 outputs the amplified signal to transmit / receive switching circuit 105.

[0065] The transmit / receive switching circuit 105 switches the signal path depending on whether the sound wave is being transmitted or received. When transmitting sound waves, the transmit / receive switching circuit 105 outputs the signal output by the power amplifier 104 to the electrostrictive vibrator 106. When receiving sound waves, the transmit / receive switching circuit 105 outputs the signal output by the electrostrictive vibrator 106 to the preamplifier 107.

[0066] The electrostrictive vibrator 106 is an element capable of converting between an electric signal and an underwater sound wave in both directions. For example, the electrostrictive vibrator 106 may be made of piezoelectric ceramics. The electrostrictive vibrator 106 corresponds to an example of a transmitting / receiving means. As described above, a plurality of electrostrictive vibrators 106 are arranged in an array so that the transmission and reception of sound waves by the sonar 11 is directional. The sonar 11 transmits directional sound waves. Specifically, the sonar 11 transmits sound waves in a direction determined by the homing sailing control unit 12. When the sound waves are received, the directivity synthesis unit 111 detects the direction from which the sound waves are coming.

[0067] Preamplifier 107 amplifies the electrical signal output from electrostrictive vibrator 106 when receiving sound waves. The electrical signal obtained by converting underwater sound waves by electrostrictive vibrator 106 is weak, and preamplifier 107 amplifies this electrical signal. Preamplifier 107 outputs the amplified signal to bandpass filter 108.

[0068] Bandpass filter 108 removes frequency components that are not required for subsequent signal processing from the signal (amplified received signal) output by preamplifier 107. In particular, this takes into consideration the fact that accurate conversion results cannot be obtained unless frequency components higher than the Nyquist frequency, which is half the sampling frequency, are removed before fast Fourier transform by fast Fourier transform unit 110. The band-pass filter 108 outputs the signal from which unnecessary frequency components have been removed to the analog-to-digital converter 109 .

[0069] Analog-to-digital converter 109 converts the analog signal output by band-pass filter 108 into a digital signal. The converted digital signal corresponds to digital received waveform data. Analog-to-digital converter 109 outputs the digital received waveform data obtained by the conversion to fast Fourier transform section 110.

[0070] Fast Fourier transform section 110 converts the received waveform data output by analog-to-digital converter 109 into level data (voltage magnitude) for each frequency component. The fast Fourier transform unit 110 outputs level data for each frequency component obtained by the transformation to the directivity synthesis unit 111.

[0071] The directivity synthesis unit 111 converts the level data for each frequency component output by the fast Fourier transform unit 110 into level data for each direction and frequency component corresponding to the array arrangement of the electrostrictive vibrators 106. This makes it possible to detect the direction of arrival of each sound wave included in the received sound wave (sound wave for each underwater vehicle 10 that is the sound wave transmitter).

[0072] The directivity synthesis unit 111 outputs level data for each direction and each frequency component to the code discrimination processing unit 112. Alternatively, the directivity synthesis unit 111 may generate level data for each frequency component only for the direction corresponding to the direction of the target ship 40 and output the level data to the code discrimination processing unit 112 .

[0073] The code discrimination processing unit 112 determines whether to maintain the target ship 40 or change the target ship 40 based on the level data for each direction and each frequency component output by the directivity synthesis unit 111. The code determination processing unit 112 corresponds to an example of a determining means. The sonar 11 corresponds to an example of a determination device in that it includes an electrostrictive vibrator 106 and a code discrimination processing unit 112 .

[0074] FIG. 17 is a diagram showing an example of the procedure of the process in which the code discrimination processing unit 112 determines whether to maintain the target ship 40 or change the target ship 40. In the process of FIG. 17, the code discrimination processing unit 112 acquires the level data for each direction and each frequency component output by the directivity synthesis unit 111 (step S101).

[0075] Then, the code discrimination processing unit 112 determines whether or not there is data (data for each frequency component) for a direction corresponding to the direction of the target ship 40 among the level data for each direction and each frequency component output by the directivity synthesis unit 111 (step S102). If it is determined that there is no data for the corresponding method (step S102: NO), the code discrimination processing unit 112 decides to maintain the target ship 40 and notifies the homing sailing control unit 12 that the target ship 40 will be maintained (step S121). After step S121, the code determination processing unit 112 ends the process of FIG.

[0076] On the other hand, if it is determined in step S102 that data in the corresponding direction exists (step S102: YES), the code determination processing unit 112 selects the data in that direction (step S103). Then, the code discrimination processing unit 112 detects the priority corresponding to the frequency component included in the selected data (step S104). For example, the code discrimination processing unit 112 detects a code, of which the pulse frequency matches the frequency component included in the selected data, from among the 63 codes shown in the example of Fig. 8, and reads out the priority associated with that code.

[0077] Then, the code discrimination processing unit 112 determines whether the read priority is higher than the priority of its own underwater vehicle 10 (step S105). The priority of its own underwater vehicle 10 is obtained as the priority associated with the unique code output by the homing traveling control unit 12.

[0078] If the code discrimination processing unit 112 determines that the read priority is equal to or lower than the priority of its own underwater vehicle 10 (step S105: NO), the process proceeds to step S121. On the other hand, if it is determined that the read priority is higher than the priority of the underwater vehicle 10 (step S105: YES), the code discrimination processing unit 112 decides to change the target vessel 40 and notifies the homing sailing control unit 12 of the change in target vessel 40 (step S111). After step S111, the code determination processing unit 112 ends the process of FIG.

[0079] Both the case of step S102: NO and the case of step S105: NO correspond to the case where the same vessel as the target vessel of the own underwater vehicle 10 is set as the target vessel and there is no other underwater vehicle 10 with a higher priority than the own underwater vehicle 10. The homing state of the other underwater vehicle 10 when the same vessel as the target vessel of the own underwater vehicle 10 is set as the target vessel and there is no other underwater vehicle 10 with a higher priority than the own underwater vehicle 10 is also referred to as "not homing." The homing state of the underwater vehicle 10 here refers to the setting status of the homing target for that underwater vehicle 10.

[0080] If step S105: YES, this corresponds to the case where the same vessel as the target vessel of the own underwater vehicle 10 is set as the target vessel, and there is another underwater vehicle 10 that has a higher priority than the own underwater vehicle 10. When the same vessel as the target vessel of the own underwater vehicle 10 is set as the target vessel, and there is another underwater vehicle 10 that has a higher priority than the own underwater vehicle 10, the homing state of the other underwater vehicle 10 is also referred to as "homing in progress."

[0081] Fig. 18 is a diagram showing an example of the relationship between the processing cycle at which the fast Fourier transform unit 110 performs fast Fourier transform and the time width of the pulse of the received sound wave. The horizontal axis of the graph in Fig. 18 represents time, and the vertical axis represents the level (intensity) of the sound wave. The pulse U51 is a pulse included in the received sound wave. The time width of the pulse U51 is defined as time T41. As described above, time T41 is determined according to conditions such as the overall length of the target ship 40 and the angle between the traveling direction of the sound wave transmitted by the sonar 11 and the longitudinal direction of the target ship 40.

[0082] Here, it is conceivable that the sonar 11 periodically repeats the processing, and that the fast Fourier transform unit 110 also periodically repeats the fast Fourier transform processing. Depending on the relationship between the time interval that the fast Fourier transform unit 110 performs the fast Fourier transform on and the reception time of the received sound wave, it is conceivable that the fast Fourier transform unit 110 may perform the fast Fourier transform on each of the two parts into which the received sound wave is divided in the time direction.

[0083] For example, consider a case where the fast Fourier transform unit 110 performs a Fourier transform on data in the time interval from time T31 to T34 and data in the time interval from time T34 to T37, respectively, and time T33, which is the start time of reception of the received sound waves, is earlier than time T34, and time T35, which is the end time of reception of the received sound waves, is later than time T34. In this case, the fast Fourier transform unit 110 performs fast Fourier transform on the portion of the received sound wave from time T33 to T34 and the portion from time T34 to T35. In this way, when the fast Fourier transform unit 110 performs a fast Fourier transform on each part of the received sound wave, there are cases where the frequency components cannot be detected correctly.

[0084] Therefore, the fast Fourier transform unit 110 may repeat the fast Fourier transform so that the periods overlap by half. In the example of FIG. 18, the fast Fourier transform unit 110 may perform fast Fourier transform on each of the time intervals from time T31 to T34, the time interval from time T32 to T36, and the time interval from time T34 to T37.

[0085] In this case, the entire time from time T33 to T35, which is the time when the sound waves are received, is included in the time interval from time T32 to T36, and it is expected that the fast Fourier transform unit 110 can correctly detect the frequency components. Furthermore, even if the reception time of the sound wave falls within the time interval indicated by time T42, the entire reception time of the sound wave is included in the time interval from time T34 to T37, and it is expected that the fast Fourier transform unit 110 will be able to correctly detect the frequency components.

[0086] The time width of the time interval that the fast Fourier transform unit 110 targets for the fast Fourier transform may be set to be included in any of the time intervals that the fast Fourier transform unit 110 targets for the fast Fourier transform, regardless of the timing at which the sonar 11 receives the sound waves. For example, if the total length of a ship is at most 350 meters and the speed of sound in water is 1,500 meters per second, the maximum time width over which sound waves are stretched by reverberation on the ship is calculated to be 350 ÷ 1,500 ≒ 0.233 seconds = 233 milliseconds. If the time width that the fast Fourier transform unit 110 targets for fast Fourier transform is set to 0.233 x 2 = 0.466 seconds or more, it is expected that the entire received sound wave will be included in one of the time intervals that the fast Fourier transform unit 110 targets for fast Fourier transform.

[0087] FIG. 19 is a diagram showing an example of a processing procedure in which the underwater vehicle 10 sets a target and performs homing navigation. In the process of Figure 19, the sonar 11 searches for a target ship 40 (step S201). Specifically, the sonar 11 searches for ships. If one or more ships are detected, the code discrimination processing unit 112 of the sonar 11 provisionally sets one of the detected ships as the target ship 40. A known method can be used as the method for searching for ships by the sonar 11. For example, the sonar 11 may search for ships by performing a general process for sonar to search for ships.

[0088] Next, the code discrimination processing unit 112 determines whether or not the target ship 40 has been detected (step S202). That is, the code discrimination processing unit 112 determines whether or not the target ship 40 has been provisionally set in step S201. If the code discrimination processing unit 112 determines that the target ship has not been detected (step S202: NO), the process returns to step S201.

[0089] On the other hand, if it is determined that the target ship has been detected, the code discrimination processing unit 112 classifies the target ship 40 (step S203). Specifically, the code discrimination processing unit 112 classifies whether the target ship 40 is an actual ship or a fake such as an acoustic decoy. The code discrimination processing unit 112 can use a known method for determining whether the target ship 40 is a fake such as an acoustic decoy as a method for classifying whether the target ship 40 is a real ship or a fake such as an acoustic decoy.

[0090] Then, the code discrimination processing unit 112 determines whether the target ship 40 is a homing target based on the classification result (step S204). Specifically, if the code discrimination processing unit 112 classifies the target ship 40 as a real ship, it determines that the target ship 40 is a homing target. On the other hand, if the code discrimination processing unit 112 classifies the target ship 40 as a fake such as an acoustic decoy, it determines that the target ship 40 is not a homing target.

[0091] If the code discrimination processing unit 112 determines that the target ship 40 is not a target for homing (step S204: NO), the process returns to step S201. On the other hand, if it is determined that the target vessel 40 is a target for homing (step S204: YES), the sonar 11 checks the homing status of other underwater vehicles 10 (step S205).

[0092] 20 is a diagram showing an example of a processing procedure in which the sonar 11 checks the homing state of another underwater vehicle 10. The sonar 11 performs the processing of FIG. 20 in step S205 of FIG. In the process of Figure 20, the sonar 11 transmits coded sound waves toward the target ship 40 (step S301). When transmitting the coded sound waves, the sonar 11 adjusts the directivity width so that ships other than the target ship 40 are outside the range of the transmission directivity of the coded sound waves. As described above, the operation of the sonar 11 to transmit coded sound waves is performed in the order of the transmission waveform generator 101, digital-to-analog converter 102, bandpass filter 103, power amplifier 104, transmission / reception switching circuit 105, and electrostrictive vibrator 106.

[0093] Next, the sonar 11 receives sound waves (step S302). In particular, the sonar 11 receives sound waves that are the encoded sound waves transmitted by the sonar 11 of the underwater vehicle 10 and reflected by the target ship 40. When receiving the sound waves, the sonar 11 adjusts the directivity width so that ships other than the target ship 40 are outside the range of the reception directivity of the sound waves.

[0094] As described above, the operation of sonar 11 to receive sound waves is performed in the order of electrostrictive transducer 106, transmit / receive switching circuit 105, preamplifier 107, bandpass filter 108, analog-to-digital converter 109, fast Fourier transform unit 110, directivity synthesis unit 111, and code discrimination processing unit 112. In particular, fast Fourier transform unit 110 performs fast Fourier transform on the received sound waves to generate level data for each frequency. Directivity synthesis unit 111 converts the level data for each frequency component output by fast Fourier transform unit 110 into level data for each direction and frequency component corresponding to the array arrangement of electrostrictive transducer 106.

[0095] Next, the code discrimination processing unit 112 detects the homing state of the other underwater vehicle 10 based on the level data for each frequency of the sound waves arriving from the direction of the target ship 40 (step S303). Specifically, the code discrimination processing unit 112 determines whether or not there is data from the direction of the target ship 40 using the processing in Figure 17. If it is determined that there is data from the direction of the target ship 40, the code discrimination processing unit 112 reads out the priority associated with the code indicated by the data from the direction of the target ship 40, and determines whether or not the read priority is higher than the priority of the underwater vehicle 10 itself. After step S303, the sonar 11 ends the processing of FIG.

[0096] When the sonar 11 finishes the processing of Figure 20, the processing returns to the processing of Figure 19, and the code discrimination processing unit 112 determines whether the homing state of the other underwater vehicle 10 is "homing in progress" (step S206). As described above, "homing in progress" corresponds to the case of step S105: YES in Figure 17. "Not homing in progress" corresponds to the case of step S102: NO and step S105: NO in Figure 17.

[0097] If the code discrimination processing unit 112 determines that the homing state of the other underwater vehicle 10 is "homing in progress" (step S206: YES), the process returns to step S201. In this case, the code discrimination processing unit 112 may notify the homing traveling control unit 12 that the target vessel 40 will be changed, as in step S111 of FIG. 17 .

[0098] On the other hand, if the code discrimination processing unit 112 determines that the homing state of the other underwater vehicle 10 is "not homing" (step S206: NO), the underwater vehicle 10 performs homing navigation toward the target ship 40 (step S207). After step S207, the underwater vehicle 10 ends the processing of FIG. When the underwater vehicle is performing homing travel in step S207, the processing from step S205 onwards may be repeated periodically.

[0099] As described above, the electrostrictive vibrator 106 transmits sound waves toward the target ship 40 , which is the target toward which the underwater vehicle 10 is heading, and receives sound waves reflected by the target ship 40 . The code discrimination processing unit 112 determines whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted sound wave and the priority associated with the received sound wave.

[0100] The sonar 11 allows multiple underwater vehicles 10 to move autonomously among multiple targets. Here, it is conceivable to guide the underwater vehicle 10 by wire from the mother ship 30, but it is difficult to individually detect the navigation sounds of many ships one by one from a distance using sonar, and furthermore, the navigation sounds of the underwater vehicle 10 overlap with sound waves arriving from the direction of the target ship 40, so it is thought to be extremely difficult to individually detect many target ships 40. Considering the azimuth resolution performance of sonar in detecting incoming sound waves, it is thought to be impossible for the mother ship 30 to individually detect many target ships 40 and many underwater vehicles 10 using sonar and to guide many underwater vehicles 10 by wire in a dispersed manner toward many target ships 40.

[0101] It is also possible to communicate between multiple underwater vehicles 10 using underwater acoustic waves and automatically assign target ships 40 to be homed to using underwater data communication, but this would require adding underwater data communication equipment to the underwater vehicle 10, which would be very costly and would likely increase the size of the underwater vehicle 10.

[0102] In contrast, with the sonar 11, by adding a processing function to an existing sonar, a large number of underwater vehicles can automatically distribute homing targets toward a large number of target ships. In this respect, the sonar 11 allows a large number of underwater vehicles to automatically distribute homing targets toward a large number of target ships at a lower cost than when underwater acoustic wave communication is performed between a plurality of underwater vehicles 10 and target ships 40 to be homing are automatically assigned by underwater data communication.

[0103] Furthermore, the electrostrictive vibrator 106 transmits and receives sound waves that are encoded using a combination of frequencies. This allows the sonar 11 to read the code from the received sound waves even if the pulse train of the encoded sound waves is stretched in the time direction and overlaps when reflected by the ship.

[0104] Furthermore, the electrostrictive vibrator 106 transmits sound waves assigned to each underwater vehicle 10 so that the earlier the underwater vehicle 10 starts moving toward the target, the higher the priority. This is expected to cause the underwater vehicle 10 to determine the target vessel 40 in descending order of priority. By having the underwater vehicle 10 determine the target vessel 40 in descending order of priority, it is expected that an underwater vehicle 10 that has already determined a target vessel 40 can avoid changing the target vessel 40 because an underwater vehicle 10 with a higher priority has set the same vessel as its own target vessel 40 as the target vessel 40. In this regard, it is expected that the sonar 11 will enable multiple underwater vehicles 10 to be efficiently distributed among multiple target vessels 40.

[0105] In addition, if the code discrimination processing unit 112 does not detect a sound wave associated with a priority higher than the priority predetermined for its own underwater vehicle 10, it decides to maintain the target, and if it detects a sound wave associated with a priority higher than the priority predetermined for its own underwater vehicle 10, it decides to change to another target. This allows the sonar 11 to direct one underwater vehicle 10 toward one target ship 40, and in this respect, it is expected that multiple underwater vehicles 10 can be efficiently distributed among multiple target ships 40.

[0106] Second Embodiment In the second embodiment, a case will be described in which a target ship 40 is set for each underwater vehicle 10 so that two underwater vehicles 10 head toward one target ship 40. The configuration of the underwater vehicle 10 in the second embodiment is the same as that in the first embodiment. In the second embodiment, the process by which the code discrimination processing unit 112 determines whether to maintain or change the target ship 40 differs from that in the first embodiment. In all other respects, the second embodiment is similar to the first embodiment.

[0107] Fig. 21 is a diagram showing an example of an image in which multiple underwater vehicles 10 are dispersed and sailing toward multiple target ships 40. Fig. 21 shows an example in which twice the number of underwater vehicles 10 as the number of target ships 40 are launched from the mother ship 30, and two underwater vehicles 10 are sailing toward one target ship 40. In particular, two underwater vehicles 10 are sailing toward the target ship 40 from each side of the one target ship 40. This is expected to enable the underwater vehicle 10 to approach the target ship 40 more reliably. As a method of homing travel in which the underwater vehicle 10 approaches one target ship 40 from both the left and right sides, for example, the method shown in Patent Publication No. 2021-134968 can be used.

[0108] FIG. 22 is a diagram showing an example of a procedure for processing in which the underwater vehicle 10 performs homing navigation with a target set. Steps S401 to S405 in FIG. 22 are the same as steps S201 to S205 in FIG.

[0109] After step S405, the code discrimination processing unit 112 determines whether there are two or more underwater vehicles 10 that have a higher priority than the underwater vehicle 10 itself and that have set the same ship as the target ship 40 of the underwater vehicle 10 as the target ship 40 (step S406). If the code discrimination processing unit 112 determines that there are two or more underwater vehicles 10 that have a higher priority than the underwater vehicle 10 itself and that have set the same ship as the target ship 40 of the underwater vehicle 10 as the target ship 40 (step S406: YES), the processing returns to step S401.

[0110] On the other hand, if it is determined that there is one or less underwater vehicle 10 that has a higher priority than the underwater vehicle 10 itself and that has set the same ship as the target ship 40 of the underwater vehicle 10 itself as its target ship 40 (step S406: NO), the code discrimination processing unit 112 determines the direction in which to approach the target ship 40 (step S407).

[0111] For example, the code discrimination processing unit 112 may determine that of the two underwater vehicles 10, the underwater vehicle 10 with the higher priority will approach from the left side of the target ship 40, and the underwater vehicle 10 with the lower priority will approach from the right side of the target ship 40. Alternatively, the code discrimination processing unit 112 may determine that of the two underwater vehicles 10, the underwater vehicle 10 that determines the target ship 40 first will approach from the left side of the target ship 40, and the underwater vehicle 10 that determines the target ship 40 later will approach from the right side of the target ship 40.

[0112] Next, the underwater vehicle 10 performs homing navigation so as to head toward the target ship 40 from the direction determined in step S407 (step S408). As described above, as a method of homing navigation in step S408, for example, the method shown in Japanese Patent Application Laid-Open No. 2021-134968 can be used. After step S408, the underwater vehicle 10 ends the processing of FIG.

[0113] However, the number of underwater vehicles 10 heading towards one target ship 40 is not limited to one or two. For example, three underwater vehicles may head towards one target ship 40. In this case, in step S406, the code discrimination processing unit 112 determines whether there are three or more underwater vehicles 10 that have a higher priority than the own underwater vehicle 10 and that have set the same ship as the target ship 40 of the own underwater vehicle 10 as the target ship 40.

[0114] As described above, when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle 10 is less than a predetermined number, the code discrimination processing unit 112 decides to maintain the target and determines the direction toward the target based on the sound wave detection status, and when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle 10 is greater than the predetermined number, it decides to change to another target.

[0115] The sonar 11 can make it possible for not just one but a predetermined number of underwater vehicles 10 to head toward one target ship 40. For example, it is possible to make the underwater vehicles 10 head toward one target ship 40 from both the left and right sides, which is expected to make it possible to more reliably bring the underwater vehicles 10 closer to the target ship 40.

[0116] Third Embodiment 23 is a diagram illustrating an example of the configuration of a determination device according to at least one embodiment. In the configuration illustrated in FIG. 23, a determination device 610 includes a transmitting / receiving unit 611 and a determination unit 612.

[0117] In this configuration, the transmitter / receiver 611 transmits sound waves toward a target toward which the underwater vehicle is heading, and receives sound waves reflected at the target. The decision unit 612 decides whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted sound waves and the priority associated with the received sound waves.

[0118] The transmitting / receiving unit 611 is an example of a transmitting / receiving means, and the determining unit 612 is an example of a determining means. The determination device 610 allows multiple underwater vehicles to move autonomously and dispersedly to multiple targets.

[0119] <Fourth embodiment> 24 is a diagram showing an example of the configuration of an underwater vehicle according to at least one embodiment. In the configuration shown in FIG. 24, an underwater vehicle 620 includes a transmitter / receiver 621, a determiner 622, and a mover 623.

[0120] With this configuration, the transmitter / receiver 621 transmits sound waves toward a target to which the underwater vehicle is heading, and receives the sound waves reflected at the target. The decision unit 622 decides whether to maintain the target or change to another target based on a comparison between the priority associated with the transmitted sound waves and the priority associated with the received sound waves. The movement unit 623 moves the underwater vehicle itself toward the set target.

[0121] The transmitting / receiving unit 621 is an example of a transmitting / receiving means, the determining unit 622 is an example of a determining means, and the moving unit 623 is an example of a moving means. According to the underwater vehicle 620, multiple underwater vehicles can be dispersed to multiple targets and move autonomously.

[0122] Fifth Embodiment 25 is a diagram illustrating an example of a processing procedure in a determination method according to at least one embodiment. The determination method illustrated in FIG. 25 includes performing control (step S611) and making a determination (step S612). In the control step (step S611), the computer controls the transmitting and receiving means so that sound waves are transmitted toward the target to which the underwater vehicle is heading and sound waves reflected at the target are received. In making a decision (step S612), the computer determines whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted sound waves with the priority associated with the received sound waves.

[0123] According to the determination method shown in FIG. 25, multiple underwater vehicles can be dispersed among multiple targets and move autonomously.

[0124] FIG. 26 illustrates an example configuration of a computer according to at least one embodiment. In the configuration shown in FIG. 26, a computer 700 includes a CPU 710, a main memory device 720, an auxiliary memory device 730, an interface 740, and a non-volatile recording medium 750.

[0125] One or more of the processes in the underwater vehicle 10, the sonar 11, the determination device 610, and the underwater vehicle 620, or a portion thereof, may be implemented in the computer 700. In this case, the operation of each of the above-described processing units is stored in the auxiliary storage device 730 in the form of a program. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above-described processes in accordance with the program. The CPU 710 also allocates storage areas in the main storage device 720 corresponding to each of the above-described storage units in accordance with the program. Communication between each device and other devices is performed by the interface 740, which has a communication function and performs communication under the control of the CPU 710. The interface 740 also has a port for the nonvolatile storage medium 750, and reads and writes information from and to the nonvolatile storage medium 750.

[0126] When the processing in the underwater vehicle 10 is implemented in the computer 700, the operation of each part of the underwater vehicle 10 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above processing in accordance with the program. Furthermore, the CPU 710 allocates a storage area in the main storage device 720 for the underwater vehicle 10 to perform processing in accordance with the program.

[0127] When the processing in the sonar 11 is implemented in the computer 700, the operation of each part of the sonar 11 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above processing in accordance with the program. Furthermore, the CPU 710 allocates a storage area in the main storage device 720 for the sonar 11 to perform processing in accordance with the program.

[0128] When the processing in the determination device 610 is implemented in the computer 700, the operation of each unit of the determination device 610 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above processing in accordance with the program. Furthermore, the CPU 710 allocates a storage area in the main storage device 720 for the determination device 610 to perform processing in accordance with the program.

[0129] When the processing in the underwater vehicle 620 is implemented in the computer 700, the operation of each part of the underwater vehicle 620 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above processing in accordance with the program. Furthermore, the CPU 710 allocates a storage area in the main storage device 720 for the underwater vehicle 620 to perform processing in accordance with the program.

[0130] One or more of the above-described programs may be recorded on nonvolatile recording medium 750. In this case, interface 740 may read the programs from nonvolatile recording medium 750. CPU 710 may then directly execute the programs read by interface 740, or may temporarily store the programs in main storage device 720 or auxiliary storage device 730 and then execute them.

[0131] Note that the processing of each part may be performed by recording a program for executing all or part of the processing performed by the underwater vehicle 10, the sonar 11, the determination device 610, and the underwater vehicle 620 on a computer-readable recording medium, and loading and executing the program recorded on this recording medium into a computer system. Note that the term "computer system" here includes hardware such as an OS (Operating System) and peripheral devices. Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc Read Only Memory), as well as storage devices such as hard disks built into computer systems. The program may be one that realizes part of the aforementioned functions, or may be one that can realize the aforementioned functions in combination with a program already stored in the computer system.

[0132] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs within the scope of the present invention. Furthermore, the above-described embodiments may be combined with other embodiments as appropriate.

[0133] Some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0134] (Appendix 1) a transmitting / receiving means for transmitting acoustic waves toward a target to which the underwater vehicle is heading and receiving acoustic waves reflected from the target; a decision means for deciding whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; A determination device comprising:

[0135] (Appendix 2) The transmitting and receiving means transmits and receives encoded acoustic waves using a combination of frequencies. 10. The determination apparatus of claim 1.

[0136] (Appendix 3) the transmitting and receiving means transmits the acoustic waves assigned to each underwater vehicle so that the earlier the underwater vehicle starts moving toward the target, the higher the priority. 10. The determination device of claim 1 or 2.

[0137] (Appendix 4) The decision means decides to maintain the target when it does not detect a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself, and decides to change to another target when it detects a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself. 4. The determination device of any one of claims 1 to 3.

[0138] (Appendix 5) The decision means decides to maintain the target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is equal to or less than a predetermined number, and determines the direction toward the target based on the detection status of the sound waves, and decides to change to another target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is greater than the predetermined number. 4. The determination device of any one of claims 1 to 3.

[0139] (Appendix 6) a transmitting / receiving means for transmitting sound waves toward a target to which the underwater vehicle is heading and receiving sound waves reflected from the target; a decision means for deciding whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; a moving means for moving the underwater vehicle itself toward a set target; An underwater vehicle equipped with:

[0140] (Appendix 7) The transmitting and receiving means transmits and receives encoded acoustic waves using a combination of frequencies. 1. An underwater vehicle as described in Appendix 6.

[0141] (Appendix 8) the transmitting and receiving means transmits the acoustic waves assigned to each underwater vehicle so that the earlier the underwater vehicle starts moving toward the target, the higher the priority. 1. An underwater vehicle as described in Appendix 6 or Appendix 7.

[0142] (Appendix 9) The decision means decides to maintain the target when it does not detect a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself, and decides to change to another target when it detects a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself. 9. An underwater vehicle according to any one of appendixes 6 to 8.

[0143] (Appendix 10) The decision means decides to maintain the target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is equal to or less than a predetermined number, and determines the direction toward the target based on the detection status of the sound waves, and decides to change to another target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is greater than the predetermined number. 9. An underwater vehicle according to any one of appendixes 6 to 8.

[0144] (Appendix 11) The computer controlling the transmitting and receiving means to transmit acoustic waves toward a target to which the underwater vehicle is heading and to receive acoustic waves reflected from the target; determining whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; A method of determining whether a

[0145] (Appendix 12) The transmitting and receiving means transmits and receives encoded acoustic waves using a combination of frequencies. The determination method described in Appendix 11.

[0146] (Appendix 13) the transmitting and receiving means transmits the acoustic waves assigned to each underwater vehicle so that the earlier the underwater vehicle starts moving toward the target, the higher the priority. The determination method described in Appendix 11 or Appendix 12.

[0147] (Appendix 14) The decision means decides to maintain the target when it does not detect a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself, and decides to change to another target when it detects a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself. 14. The method of any one of appendices 11 to 13.

[0148] (Appendix 15) The decision means decides to maintain the target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is equal to or less than a predetermined number, and determines the direction toward the target based on the detection status of the sound waves, and decides to change to another target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is greater than the predetermined number. 14. The method of any one of appendices 11 to 13.

[0149] (Appendix 16) On the computer, controlling the transmitting and receiving means to transmit acoustic waves toward a target toward which the underwater vehicle is heading and to receive acoustic waves reflected from said target; determining whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves and the priority associated with the received acoustic waves; A program that executes the following.

[0150] (Appendix 17) The transmitting and receiving means transmits and receives encoded acoustic waves using a combination of frequencies. 16. The program described in Appendix 16.

[0151] (Appendix 18) the transmitting and receiving means transmits the acoustic waves assigned to each underwater vehicle so that the earlier the underwater vehicle starts moving toward the target, the higher the priority. 18. The program according to claim 16 or 17.

[0152] (Appendix 19) The decision means decides to maintain the target when it does not detect a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself, and decides to change to another target when it detects a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself. 19. The program of any one of appendices 16 to 18.

[0153] (Appendix 20) The decision means decides to maintain the target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is equal to or less than a predetermined number, and determines the direction toward the target based on the detection status of the sound waves, and decides to change to another target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is greater than the predetermined number. 19. The program of any one of appendices 16 to 18. [Explanation of symbols]

[0154] 10, 620 Underwater vehicle 11 Sonar 12 Homing navigation control unit 13 Payload Area 14 Power source area 15 Prime Mover 16 Steering control unit 17 Screw propeller 18 Rudder 20 Underwater vehicle group 30 Mothership 40 target ship 50 Target fleet 101 Transmission waveform generator 102 Digital-to-Analog Converter 103, 108 Bandpass filters 104 Power Amplifier 105 Transmit / receive switching circuit 106 Electrostrictive vibrator 107 Preamp 109 Analog-to-Digital Converter 110 Fast Fourier Transform 111 Directional synthesis section 112 Code discrimination processing unit 610 Determination device 611, 621 Transmitter / Receiver 612, 622 Decision Section 623 Mobile Department

Claims

1. a transmitting / receiving means for transmitting acoustic waves toward a target to which the underwater vehicle is heading and receiving acoustic waves reflected from the target; a decision means for deciding whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; A determination device comprising:

2. The transmitting and receiving means transmits and receives encoded acoustic waves using a combination of frequencies. The determination device of claim 1 .

3. the transmitting and receiving means transmits the acoustic waves assigned to each underwater vehicle so that the earlier the underwater vehicle starts moving toward the target, the higher the priority. The determination device of claim 1 .

4. The decision means decides to maintain the target when it does not detect a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself, and decides to change to another target when it detects a sound wave associated with a priority higher than the predetermined priority of the underwater vehicle itself. A determination device according to any one of claims 1 to 3.

5. The decision means decides to maintain the target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is equal to or less than a predetermined number, and determines the direction toward the target based on the detection status of the sound waves, and decides to change to another target when the number of detected sound waves associated with a priority higher than the predetermined priority of the underwater vehicle is greater than the predetermined number. A determination device according to any one of claims 1 to 3.

6. a transmitting / receiving means for transmitting sound waves toward a target to which the underwater vehicle is heading and receiving sound waves reflected from the target; a decision means for deciding whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; a moving means for moving the underwater vehicle itself toward a set target; An underwater vehicle equipped with:

7. The computer controlling the transmitting and receiving means to transmit acoustic waves toward a target to which the underwater vehicle is heading and to receive acoustic waves reflected from the target; determining whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves with the priority associated with the received acoustic waves; A method of determining whether a

8. On the computer, controlling the transmitting and receiving means to transmit acoustic waves toward a target toward which the underwater vehicle is heading and to receive acoustic waves reflected from said target; determining whether to maintain the target or change to another target based on a comparison of the priority associated with the transmitted acoustic waves and the priority associated with the received acoustic waves; A program that executes the following.

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