JP2019135472A - Velocity measurement system and velocity measurement method - Google Patents

Abstract

To expand the range of the distance of an underwater mobile body from the sea bottom, which can measure a ground velocity of the underwater mobile body.SOLUTION: A sound source device 3 is installed on the sea bottom 2. The sound source device 3 includes a function for transmitting an acoustic signal 7 obtained by connecting a waveform with only one peak existing in autocorrelation in a set time interval a plurality of times. The underwater mobile body 4 includes a wave receiving array 5 and an arithmetic unit 6. In the arithmetic unit 6, a first detection unit 10 acquires a signal arrival direction D in which the acoustic signal 7 arrives on the basis of information of the acoustic signal 7 received by the wave receiving array 5, and a second detection unit 11 acquires a velocity v related to the signal arrival direction D of the underwater mobile body 4 by using a Doppler effect. After that, a velocity measurement unit 12 acquires a ground velocity V of the underwater mobile body 4 in a movement direction Dv by using the fact that the acquired velocity v is a vector obtained by orthogonally projecting a velocity vector of the ground velocity V related to the movement direction Dv of the underwater mobile body 4 in the signal arrival direction D.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a speed measurement system and a speed measurement method used for measuring a ground speed of an underwater moving body.

  Detecting the position of an underwater vehicle that moves in the water is important for moving the underwater vehicle along a planned path.

  In addition, for example, when the seafloor is explored by an exploration device mounted on an underwater mobile body, information on the direct position of an object to be detected such as an object detected by the exploration device or the structure of the seabed is usually moved underwater. This is position information in a coordinate space fixed to the body. Therefore, in order to specify the position of the detected object in the coordinate space fixed to the earth such as latitude and longitude, the position of the underwater moving body when the exploration is performed is detected and the underwater movement is detected. It is necessary to perform coordinate conversion processing based on body position information. Therefore, in order to obtain the position of the object to be detected by exploring the seabed, it is necessary to detect the position of the underwater moving body.

  As one of methods for detecting the position of an underwater moving body that moves underwater, a method using an inertial navigation device together with a ground speed meter is known (for example, see Patent Document 1).

  As a ground speed meter mounted on an underwater moving body, a Doppler log (also referred to as DVL: Doppler Velocity Log) is widely used.

  In the inertial navigation apparatus, when the underwater moving body is moved, information on the moving direction of the underwater moving body can be continuously acquired at set time intervals.

  In addition, in the Doppler log, information on the ground speed of the underwater moving body can be continuously acquired for the underwater moving body moving in the water at set time intervals.

  Furthermore, for an underwater vehicle, for example, when the underwater vehicle is floating on the surface of the water, the position of the underwater vehicle using a global navigation satellite system (GNSS) such as GPS is fixed in a coordinate space fixed to the earth. The identified part is set in advance as a movement start point.

  After that, for the underwater vehicle that has started moving from the movement start point, the information on the moving direction obtained by the inertial navigation device and the information on the ground speed in the moving direction obtained by the Doppler log are obtained over time. The position of the underwater moving body can be detected by sequentially integrating and calculating the amount of movement from the movement start point.

JP 2005-321225 A

  However, in the measurement of the ground speed of an underwater vehicle using a Doppler log, the sound wave (ultrasonic wave) signal transmitted from the transmitter of the Doppler log installed in the underwater vehicle to the seabed is reflected on the seabed, and the signal Must be received by a Doppler log receiver.

  Therefore, in the Doppler log, the energy of the sound wave signal transmitted from the transmitter is attenuated according to the distance reciprocating between the underwater moving body and the seabed.

  Further, among the reflected waves reflected from the seabed by the sound wave signal, only the reflected waves directed toward the underwater moving body can be used by the Doppler log. Therefore, the energy of the reflected wave reflected toward the direction other than the direction of the underwater moving body is dissipated. In addition, when the sea bottom is a bottom sediment that is weak in the reflection of sound waves such as sand and mud, the energy of the reflected wave toward the underwater moving body becomes weaker.

  Therefore, although the Doppler log varies depending on the model, the maximum measurement range is set to about 100 m to 300 m.

  Therefore, when the underwater vehicle is at a position where the distance to the seabed (altitude from the seabed) exceeds the maximum measurement range of the Doppler log, the ground speed cannot be measured using the Doppler log. It is a fact.

  Therefore, in the past, when using a submerged mobile unit in an area where the water depth exceeds the maximum measurement range of the Doppler log, for example, when exploring the seabed, the submerged mobile unit is at a distance (altitude) from the sea surface to the seabed. During a dive to a depth that is within the maximum measurement range of the Doppler log, the ground speed measurement result cannot be obtained from the Doppler log, and therefore a position error accumulates during this time.

  Therefore, the present invention can measure the ground speed of the underwater moving body and can expand the range of the distance from the bottom of the underwater moving body that can measure the ground speed compared to the Doppler log. It is an object of the present invention to provide a speed measurement system and a speed measurement method that can be performed.

  In order to solve the above problems, the present invention provides a sound source device installed on the bottom of the water, a receiving array provided on the underwater moving body, and the ground of the underwater moving body based on information received from the receiving array. A calculation device for obtaining a speed, wherein the sound source device has a function of transmitting an acoustic signal obtained by connecting a waveform having only one peak in autocorrelation at a set time interval a plurality of times. Is based on information of the acoustic signal received by the receiving array, a first detector for obtaining a signal arrival direction from which the acoustic signal arrives, and information of the acoustic signal received by the receiving array Based on the second detection unit for determining the speed of the underwater moving body related to the signal arrival direction, information received from the first detection unit, and information received from the second detection unit, Find the ground speed of an underwater vehicle And speed measuring system having a configuration in which a degree measurement unit.

  A plurality of the sound source devices are provided, and each of the plurality of sound source devices has a function of transmitting the acoustic signals that can be distinguished from each other.

  The computing device includes a first detection unit that determines a signal arrival direction in which each acoustic signal arrives based on information of each acoustic signal from each sound source device received by the receiving array; A second detection unit that obtains the velocity of each signal arrival direction of the underwater moving body based on the information of each acoustic signal from each sound source device received by the receiving array. .

  In addition, a step of transmitting an acoustic signal obtained by connecting a waveform having only one peak in autocorrelation at a set time interval from a sound source device installed at the bottom of the water at a set time interval; Receiving the acoustic signal with a wave array, obtaining a signal arrival direction of the acoustic signal based on information of the acoustic signal received with the receiving array, and receiving the acoustic signal with the receiving array. The step of obtaining the speed of the underwater mobile body in relation to the signal arrival direction based on the information of the acoustic signal, the information of the signal arrival direction of the acoustic signal, and the speed of the underwater mobile body in relation to the signal arrival direction. And a step of obtaining the ground speed of the underwater moving body based on the above information.

  According to the speed measurement system and the speed measurement method of the present invention, it is possible to measure the ground speed of the underwater mobile body, and to increase the range of the distance from the bottom of the underwater mobile body that enables measurement of the ground speed. Can be achieved.

It is the schematic which shows 1st Embodiment of a speed measurement system. It is a figure for demonstrating the principle which detects the speed of the signal arrival direction by a speed measurement system. It is a figure for demonstrating the principle which calculates | requires the ground speed of an underwater moving body from the information of the speed of a signal arrival direction with a speed measurement system. It is a schematic side view which shows the outline of 2nd Embodiment of a speed measurement system. It is a figure for demonstrating the principle which calculates | requires the ground speed of the underwater moving body in the speed measurement system of FIG. It is a figure for demonstrating the example which carries out coordinate conversion of the ground speed of the measured underwater moving body to the coordinate system fixed to the underwater moving body. It is a schematic perspective view which shows the outline of 3rd Embodiment of a speed measurement system. It is a figure for demonstrating the principle which calculates | requires the ground speed of the underwater moving body in the speed measurement system of FIG. It is a figure which shows another example of the acoustic signal transmitted from a sound source device as 4th Embodiment of a speed measurement system. It is a figure for demonstrating the principle which detects the speed of the signal arrival direction by the speed measurement system using the acoustic signal of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows a first embodiment of a speed measurement system, FIG. 1 (a) is a schematic side view showing an overall configuration, and FIG. 1 (b) shows details of an arithmetic device provided in an underwater moving body. FIG. FIG. 2 is a diagram for explaining the principle of detecting the speed related to the signal arrival direction of the underwater moving body by the speed measurement system. FIG. 2 (a) is a diagram illustrating a signal transmitted by the sound source device. (b), (c), and (d) are diagrams showing signals received by the receiving array of the underwater vehicle according to the change in the distance between the underwater vehicle and the sound source device. FIG. 3 is a diagram for explaining the principle of obtaining the speed of the underwater moving body from the speed information in the signal arrival direction by the speed measurement system.

  The speed measurement system of the present embodiment is indicated by reference numeral 1 in FIG. 1A, and includes a sound source device 3 installed on the seabed 2, a receiving array 5 provided on the underwater moving body 4, and a receiving array. And an arithmetic device 6 for obtaining the ground speed V of the underwater vehicle 4 based on the information received from the underwater vehicle 4.

  The sound source device 3 includes a wave transmission unit 8 that transmits the acoustic signal 7 to the outside.

  As shown in FIG. 2A, the acoustic signal 7 transmitted from the sound source device 3 from the transmission unit 8 has a waveform with only one peak in the autocorrelation, and a set time interval. At T0, for example, the signal is connected twice. 2A shows an example in which the acoustic signal 7 is a signal obtained by connecting a waveform having only one peak in the autocorrelation twice at a set time interval T0. Of course, a waveform in which only one peak exists in the autocorrelation may be a signal obtained by connecting a plurality of times three or more times. As a waveform having only one peak in this type of autocorrelation, for example, it is preferable to use a waveform of an M-sequence signal, a TSP signal, or a Gold sequence signal, but is not limited thereto.

  The sound source device 3 has a function of sequentially transmitting the acoustic signal 7 from the transmission unit 8 repeatedly at a set transmission interval.

  In the present embodiment, as will be described later, when measuring the ground speed of the underwater mobile body 4, information on the position of the sound source device 3 installed on the seabed 2 is not particularly required.

  Therefore, the sound source device 3 is inserted into the sea from a ship (not shown) such as a mother ship of the underwater moving body 4 before starting the operation of the underwater moving body 4 in the sea area where the underwater moving body 4 is operated. What is necessary is just to make it install in the seabed 2 by making it sink to the seabed 2 with the weight of the ballast part 9 with which the apparatus 3 was equipped.

  In addition, when the sound source device 3 performs the repeated transmission of the acoustic signal 7 from the wave transmitting unit 8 at the time when the underwater moving body 4 is operated, the timing and trigger for starting the repeated transmission of the acoustic signal 7 are as follows: You can set it freely.

  For example, the sound source device 3 may start repetitive transmission of the acoustic signal 7 from the wave transmission unit 8 at the time when the sound source device 3 is thrown into the sea from a ship. Alternatively, when it is detected that the sound source device 3 has reached the water depth set by a water depth meter (not shown) provided in the sound source device 3 after being introduced into the sea from the ship, the acoustic signal 7 from the wave transmission unit 8 is detected. May be started repeatedly. In addition, after the sound source device 3 is installed on the seabed and receives an operation start command from the ship or the underwater moving body 4 by acoustic communication, the sound source device 3 starts to repeatedly transmit the acoustic signal 7 from the wave transmitting unit 8. Good.

  Furthermore, from the viewpoint of collecting and reusing the sound source device 3, an acoustic separation device (releaser) (not shown) that separates the ballast unit 9 is received when a separation command is received from the ship or the underwater moving body 4 by acoustic communication. It is preferable to provide a configuration. In addition, what is necessary is just to make this acoustic isolation | separation apparatus have the structure and function similar to the existing acoustic isolation | separation apparatus used for the collection | recovery of the observation equipment and transponder installed in the seabed.

  In the sound source device 3 shown in FIG. 1, the arrangement, shape, size, shape of the entire device, and the like of the transmission unit 8 and the ballast unit 9 are for convenience of illustration. Of course, in 3, it may be changed freely. In addition, the size ratio of the sound source device 3 to the underwater moving body 4 is also for convenience of illustration, and does not reflect the actual size ratio.

  The receiving array 5 is preferably installed on the lower surface side of the underwater vehicle 4. This is because the acoustic signal 7 transmitted from the sound source device 3 installed on the seabed 2 comes from directly below or obliquely below the underwater vehicle 4 that moves at an altitude from the seabed 2. This is because the signal 7 is easily received by the receiving array 5.

  The wave receiving array 5 is configured to include a plurality of hydrophones (not shown) at intervals and arrangements set in the front-rear direction and the left-right direction of the underwater moving body 4. As a result, the receiving array 5 is configured such that the phase of the acoustic signal 7 received by each hydrophone shifts according to the direction in which the acoustic signal 7 arrives. The receiving array 5 is configured to send the information of the acoustic signal 7 received by each hydrophone to the arithmetic device 6 as it is.

  As shown in FIG. 1B, the arithmetic unit 6 detects a direction in which the acoustic signal 7 arrives as a signal arrival direction D based on information on the acoustic signal 7 received from the receiving array 5. 10 and a second detection unit 11 that detects a speed v related to the signal arrival direction D of the underwater vehicle 4.

  In the present embodiment, the arithmetic device 6 has a function of receiving information related to the moving direction Dv of the underwater moving body 4 from the detecting device 13 that detects the moving direction Dv of the underwater moving body 4. As the detection device 13 for detecting the moving direction Dv of the underwater moving body 4, it is preferable to use an inertial navigation device widely provided in the underwater moving body 4, but it is detected separately from the inertial navigation device. It is good also as a structure provided with the apparatus 13. FIG.

  Furthermore, in this embodiment, the arithmetic unit 6 receives information on the signal arrival direction D received from the first detection unit 10 and information on the velocity v related to the signal arrival direction D of the underwater moving body 4 received from the second detection unit 11. And a speed measuring unit 12 for obtaining the ground speed V of the underwater moving body 4 based on the information on the moving direction Dv of the underwater moving body 4 received from the detection device 13.

  When the first detection unit 10 receives the information of the received acoustic signal 7 from the receiving array 5, the first detecting unit 10 receives the wave based on the phase shift of the acoustic signal 7 received by each hydrophone of the receiving array 5. A function of detecting a direction in which the acoustic signal 7 arrives with respect to the array 5 as a signal arrival direction D is provided.

  In addition, since the technique which detects the direction of a sound source using the array of a some hydrophone is a technique widely used in the technical field of acoustic positioning etc., detailed description of a detection principle is abbreviate | omitted.

  When the second detection unit 11 receives the information of the received acoustic signal 7 from the receiving array 5, the second detection unit 11 has a function of obtaining the velocity v related to the signal arrival direction D of the underwater moving body 4 by the following processing.

  That is, when the second detection unit 11 receives the information of the received acoustic signal 7 from the receiving array 5, the second detection unit 11 performs a correlation process on the acoustic signal 7, and the results shown in FIGS. As shown, a waveform having two peaks along the time axis is obtained. Further, the second detection unit 11 obtains a time interval T1 between adjacent peaks along the time axis for the obtained waveform.

  When the sound signal 7 transmitted from the sound source device 3 is a sound signal 7 in a form in which a waveform having only one peak in the autocorrelation is connected three or more times at a set time interval T0. The second detection unit 11 may perform the following processing. That is, in this case, the second detection unit 11 first performs correlation processing on the acoustic signal 7 received by the receiving array 5 to obtain a waveform having three or more peaks along the time axis. Next, the 2nd detection part 11 calculates | requires separately the time interval of the peaks which adjoin along a time axis about the calculated | required waveform. Next, the second detection unit 11 performs an averaging process based on the obtained time intervals, and performs a process of setting the result as a time interval T1 between adjacent peaks along the time axis. Therefore, according to this method, an effect of obtaining a more stable value for the time interval T1 obtained by the second detection unit 11 can be expected.

  For the acoustic signal 7 transmitted from the sound source device 3, the second detection unit 11 sets the time interval T0 between peaks adjacent to each other along the time axis in the waveform after correlation processing as shown in FIG. Are stored in advance.

  Next, the 2nd detection part 11 compares the time interval T1 calculated | required based on the received signal information with the time interval T0 based on the transmission signal information shown to Fig.2 (a).

  As a result of this comparison, as shown in FIG. 2B, when the time interval T1 is not changed from the time interval T0 shown in FIG. 2A, the Doppler effect is not acting. It can be seen that the speed of the underwater vehicle 4 with respect to the signal arrival direction D is zero. That is, in this case, it can be seen that the underwater moving body 4 does not move in a direction approaching the sound source device 3 and does not move in a direction away from the sound source device 3.

  On the other hand, as shown in FIG. 2 (c), when the time interval T1 is smaller than the time interval T0 shown in FIG. 2 (a), it is due to the Doppler effect. It can be seen that the signal arrival direction D moves in a direction approaching the sound source device 3. Furthermore, from the amount of decrease of the time interval T1 with respect to the time interval T0, the speed at which the underwater vehicle 4 moves in the direction of approaching the sound source device 3 along the signal arrival direction D can be obtained.

  On the other hand, as shown in FIG. 2 (d), when the time interval T1 is larger than the time interval T0 shown in FIG. 2 (a), it is due to the Doppler effect. It can be seen that the direction D is moving away from the sound source device 3. Further, from the increase amount of the time interval T1 with respect to the time interval T0, the speed at which the underwater moving body 4 moves in the direction away from the sound source device 3 along the signal arrival direction D can be obtained.

  Therefore, the second detection unit 11 compares the time interval T1 obtained based on the received signal information with the time interval T0 based on the transmission signal information shown in FIG. 2A based on the above principle. Thus, the velocity v related to the signal arrival direction D of the underwater vehicle 4 is obtained.

  The speed vector of the velocity v related to the signal arrival direction D of the underwater mobile body 4 thus obtained is the speed vector of the ground speed V related to the true movement direction Dv of the underwater mobile body 4 as shown in FIG. This means a vector orthogonally projected in the signal arrival direction D.

  Therefore, the speed measurement unit 12 of the arithmetic device 6 includes information on the signal arrival direction D from the first detection unit 10 and information on the speed v related to the signal arrival direction D of the underwater moving body 4 from the second detection unit 11. Is received from the detection device 13 and the speed vector of the speed v related to the signal arrival direction D of the underwater mobile body 4 is obtained with respect to the movement direction Dv of the underwater mobile body 4. Perform a calculation to find the inverse mapping of the orthogonal projection of.

  At this time, as shown in FIG. 3, from the position of the tip of the velocity vector of the velocity v with respect to the signal arrival direction D of the underwater moving body 4, the virtual plane 14 perpendicular to the signal arrival direction D and the position of the underwater moving body 4. The position of the intersection with the straight line extending in the movement direction Dv is the position of the tip of the speed vector of the ground speed V with respect to the movement direction Dv of the underwater moving body 4.

  Therefore, the speed measuring unit 12 can obtain the speed vector of the ground speed V related to the moving direction Dv of the underwater moving body 4 by geometric calculation.

  Thus, in the speed measurement system 1 of the present embodiment, the ground speed V related to the moving direction Dv of the underwater moving body 4 can be measured based on the above processing by the arithmetic device 6.

  In FIG. 3, the direction of the underwater moving body 4 and the moving direction Dv of the underwater moving body 4 are illustrated so as to match. However, actually, the moving direction Dv of the underwater moving body 4 detected by the detection device 13 is affected by disturbance such as a tidal current even when the underwater moving body 4 is moving forward. Therefore, it does not always coincide with the direction of the underwater moving body 4.

  For this reason, when information on the moving speed of the underwater moving body 4 in the front-rear direction, the left-right direction, and the up-down direction is required, the speed measurement unit 12 of the arithmetic device 6 obtains the information as described above. For the ground speed V related to the moving direction Dv of the underwater moving body 4, the speed components in the respective axial directions fixed to the underwater moving body 4 in the front-rear direction, the left-right direction, and the up-down direction may be obtained.

  Further, in the speed measurement system 1 of the present embodiment, the acoustic signal 7 transmitted from the sound source device 3 may be directly received by the receiving array 5 provided in the underwater moving body 4, and thus is required in the Doppler log. As described above, it is not necessary to reciprocate the sound wave between the underwater vehicle 4 and the seabed 2 or to reflect the sound wave on the seabed 2.

  Therefore, according to the speed measurement system 1 of the present embodiment, energy loss until the acoustic signal 7 transmitted from the sound source device 3 reaches the wave receiving array 5 of the underwater mobile body 4 can be suppressed. The range of the distance from the seabed 2 of the underwater vehicle 4 that enables measurement of V can be expanded. For example, according to the speed measurement system 1 of the present embodiment, the range of the distance from the seabed 2 of the underwater mobile body 4 in which the ground speed V can be measured is twice that of the case of the Doppler log. It becomes possible to greatly expand to the above.

  Therefore, when using the underwater vehicle 4 in a deep water region that exceeds the maximum measurement range of the Doppler log, for example, even when searching for the seabed, according to the speed measurement system 1 of the present embodiment. The ground speed V can be continuously measured while the underwater vehicle 4 is submerged from the sea surface to the vicinity of the seabed 2.

  Therefore, by using the speed measurement system 1 of the present embodiment in combination with an inertial navigation device instead of the conventional Doppler log or in combination with the Doppler log, in a deep water region that exceeds the maximum measurement range of the Doppler log. Even when the underwater moving body 4 is used, the position of the underwater moving body 4 can be detected with higher accuracy.

[First Application Example of First Embodiment]
In the same configuration as the first embodiment, the sound source device 3 has a function of switching and transmitting acoustic signals 7 having two different frequencies from the wave transmitting unit 8 and a distance measuring unit that measures the distance to the underwater moving body 4. When the distance to the underwater moving body 4 measured by the function and the distance measuring function is longer than the set reference distance, the acoustic signal 7 on the low frequency side is transmitted from the transmission unit 8 and measured by the distance measuring function. In addition, when the distance to the underwater moving body 4 is equal to or less than the set reference distance, a function of transmitting the high-frequency acoustic signal 7 from the wave transmitting unit 8 may be provided.

  Note that the ranging function provided in the sound source device 3 is, for example, an existing underwater distance detection in which a transponder provided in the underwater mobile body 4 returns a sound ranging signal transmitted from a transceiver provided in the sound source device 3. An apparatus may be adopted.

  It should be noted that the underwater moving body 4 may have a distance measuring function up to the sound source device 3 so that the measurement result of the distance between the underwater moving body 4 and the sound source device 3 is given to the sound source device 3 by acoustic communication. Of course.

  In this way, the speed measurement system 1 in this application example expands the maximum measurement range in accordance with the distance between the sound source device 3 and the underwater mobile body 4 for the measurement function of the ground speed V of the underwater mobile body 4. And high accuracy can be achieved together.

[Second Application Example of First Embodiment]
In the same configuration as that of the first embodiment, when the receiving array 5 included in the underwater moving body 4 receives the acoustic signal 7 from the sound source device 3, the directivity by beam forming is directed toward the signal arrival direction D. You may make it provide the function to form.

  In this way, the speed measurement system 1 in this application example can be made less susceptible to underwater noise.

[Second Embodiment]
FIG. 4 shows a second embodiment of the speed measurement system, FIG. 4 (a) is a schematic side view showing the overall configuration, and FIG. 4 (b) shows details of the arithmetic device provided in the underwater moving body. FIG. FIG. 5 is a diagram for explaining the principle of obtaining the speed of the underwater moving body from the speed information in the two signal arrival directions by the speed measurement system. FIG. 6 is a diagram for explaining an example of coordinate conversion of the measured ground speed of the underwater moving body into a coordinate system fixed to the underwater moving body. FIG. 6A illustrates the measured ground speed. FIG. 6B is a diagram showing the ground speed, and FIG. 6B is a diagram in which the ground speed is coordinate-converted from the oblique coordinate system to a coordinate system fixed to the underwater moving body.

  4 (a) (b), FIG. 5, FIG. 6 (a) (b), the same components as those shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. .

  The speed measurement system of this embodiment is indicated by reference numeral 1A in FIG. 4A. In the same configuration as that of the first embodiment, instead of the configuration using one sound source device 3, two sound sources are used. The apparatus 3a, 3b is used.

  The sound source device 3a and the sound source device 3b have the same configuration as the sound source device 3 in the first embodiment, and have a function of transmitting an acoustic signal 7a and an acoustic signal 7b that can be distinguished from each other. Note that both the acoustic signal 7a and the acoustic signal 7b have only one peak in the autocorrelation, similar to the acoustic signal 7 (see FIG. 2A) transmitted from the sound source device 3 in the first embodiment. This is a signal obtained by connecting a plurality of waveforms at a set time interval T0.

  The sound source device 3a and the sound source device 3b are installed at different positions on the seabed 2.

  In the arithmetic device 6 in the present embodiment, as shown in FIG. 4B, the first detection unit 10 determines the direction in which the acoustic signal 7 a arrives based on the information of the acoustic signal 7 a received from the receiving array 5. A function of detecting the signal arrival direction Da and a function of detecting the direction of arrival of the acoustic signal 7b as the signal arrival direction Db based on the information of the acoustic signal 7b received from the receiving array 5 are provided.

  The second detection unit 11 in this embodiment is based on the information of the acoustic signal 7a received from the receiving array 5 using the same principle as described in FIGS. 2 (a), (b), (c), and (d). In addition, a function for obtaining the velocity va related to the signal arrival direction Da of the underwater vehicle 4 and a function for obtaining the velocity vb related to the signal arrival direction Db of the underwater vehicle 4 based on the information of the acoustic signal 7b received from the receiving array 5. It is equipped with.

  The speed vector of the speed va related to the signal arrival direction Da of the underwater mobile body 4 obtained in this manner is the speed vector of the ground speed V related to the true movement direction Dv of the underwater mobile body 4 as shown in FIG. It means a vector orthogonally projected in the signal arrival direction Da.

  Further, the obtained velocity vector of the velocity vb related to the signal arrival direction Db of the underwater mobile body 4 is the signal of the velocity vector of the ground speed V related to the true movement direction Dv of the underwater vehicle 4 as shown in FIG. It means a vector orthogonally projected in the direction Db.

  Therefore, as shown in FIG. 5, the virtual plane 15 perpendicular to the signal arrival direction Da at the position of the tip of the velocity vector of the speed va with respect to the signal arrival direction Da of the underwater vehicle 4 and the signal arrival direction of the underwater vehicle 4 When the virtual plane 16 perpendicular to the signal arrival direction Db is formed at the position of the tip of the speed vector of the speed vb related to Db, the position of the tip of the speed vector of the ground speed V related to the moving direction Dv of the underwater moving body 4 is 15 and the imaginary plane 16 on the intersection line 17.

  At this time, if the underwater moving body 4 is arranged other than directly above the straight line connecting the sound source device 3a and the sound source device 3b, the virtual plane 15, the virtual plane 16, and the intersecting line 17 are inclined in the vertical direction. A straight line extending to

  In view of this point, the speed measurement unit 12 according to the present embodiment provides at least information regarding the angle in the vertical direction with respect to the moving direction Dv of the underwater moving body 4 from the detection device 13 that detects the moving direction Dv of the underwater moving body 4. Has the function to receive.

  Accordingly, the speed measurement unit 12 performs geometric calculation based on the intersection line 17 between the virtual plane 15 and the virtual plane 16 and information on the angle in the vertical direction of the moving direction Dv of the underwater moving body 4. Thus, the ground speed V of the underwater vehicle 4 can be obtained.

  In this embodiment, the speed measuring unit 12 may of course obtain the ground speed V of the underwater moving body 4 by the same processing as the speed measuring unit 12 of the first embodiment. That is, the speed measuring unit 12 receives the information on the moving direction Dv of the underwater moving body 4 from the detection device 13, and the speed vector of the speed va regarding the signal arrival direction Da of the underwater moving body 4 or the signal arrival of the underwater moving body 4. The ground speed V of the underwater vehicle 4 may be obtained by performing a calculation for obtaining a reverse projection of the orthogonal projection in the direction Dv of the underwater vehicle 4 with respect to the velocity vector of the speed vb in the direction Db.

  Therefore, the speed measurement system 1A of the present embodiment can be used in the same manner as the speed measurement system 1 of the first embodiment to obtain the same effect.

  Furthermore, in the present embodiment, as shown in FIG. 6A, when the signal arrival direction Da and the signal arrival direction Db intersect at a certain angle φ, the velocity vector of the velocity va with respect to the signal arrival direction Da, The ground speed V of the underwater vehicle 4 obtained from the speed vector of the speed vb with respect to the signal arrival direction Db can be decomposed and displayed into a speed component v1 in the signal arrival direction Da and a speed component v2 in the signal arrival direction Db. it can. 6A, for convenience of explanation, it is assumed that the signal arrival direction Da, the signal arrival direction Db, and the velocity vector of the ground velocity V are located on the same plane (FIG. 6B is the same). ).

  In this case, the relational expression of the speed va related to the signal arrival direction Da, the speed vb related to the signal arrival direction Db, the speed component v1 of the signal arrival direction Da of the ground speed V, and the speed component v2 of the signal arrival direction Db is Is represented by the following equation.

  In this state, as shown in FIG. 6B, when the velocity in the orthogonal coordinate system of the front-rear direction Dy and the left-right direction Dx fixed to the underwater moving body 4 is required, the coordinate conversion by the following equation is performed. Then, the speed vy in the front-rear direction Dy and the speed vx in the left-right direction Dx of the underwater moving body 4 may be obtained.

[Third Embodiment]
FIG. 7 shows a third embodiment of the speed measurement system, FIG. 7 (a) is a schematic perspective view showing the overall configuration, and FIG. 7 (b) shows the details of the arithmetic unit provided in the underwater moving body. FIG. FIG. 8 is a diagram for explaining the principle of obtaining the speed of the underwater moving body from the speed information in the three signal arrival directions by the speed measurement system.

  7A, 7 </ b> B, and 8, the same components as those shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The speed measurement system of the present embodiment is denoted by reference numeral 1B in FIG. 7A. In the same configuration as in the first embodiment, instead of the configuration using one sound source device 3, three sound sources The apparatus 3c, 3d, 3e is used.

  The sound source device 3c, the sound source device 3d, and the sound source device 3e have the same configuration as the sound source device 3 in the first embodiment, and have a function of transmitting the acoustic signal 7c, the acoustic signal 7d, and the acoustic signal 7e that can be distinguished from each other. Yes. Note that each of the acoustic signals 7c, 7d, and 7e has only one peak in the autocorrelation like the acoustic signal 7 (see FIG. 2A) transmitted from the sound source device 3 in the first embodiment. This is a signal obtained by connecting existing waveforms a plurality of times at a set time interval T0.

  The sound source device 3c, the sound source device 3d, and the sound source device 3e are installed at different positions on the seabed 2.

  In the arithmetic device 6 in the present embodiment, as shown in FIG. 7B, the first detection unit 10 determines the direction in which the acoustic signal 7c arrives based on the information of the acoustic signal 7c received from the receiving array 5. The function of detecting the signal arrival direction Dc, the function of detecting the direction of arrival of the acoustic signal 7d as the signal arrival direction Dd based on the information of the acoustic signal 7d received from the receiving array 5, and the direction of arrival of the acoustic signal 7e As a signal arrival direction De.

  The second detection unit 11 in the present embodiment is based on the information of the acoustic signal 7c received from the wave receiving array 5 using the same principle as described in FIGS. 2 (a), (b), (c), and (d). In addition, a function for obtaining the velocity vc related to the signal arrival direction Dc of the underwater vehicle 4 and a function for obtaining the velocity vd related to the signal arrival direction Dd of the underwater vehicle 4 based on the information of the acoustic signal 7d received from the receiving array 5. And a function for obtaining a velocity ve related to the signal arrival direction De of the underwater vehicle 4 based on the information of the acoustic signal 7e received from the wave receiving array 5.

  The speed vector of the speed vc related to the signal arrival direction Dc of the underwater mobile body 4 thus obtained is the speed vector of the ground speed V related to the true movement direction Dv of the underwater mobile body 4 as shown in FIG. This means a vector orthogonally projected in the signal arrival direction Dc.

  Further, the speed vector of the speed vd related to the signal arrival direction Dd of the underwater mobile body 4 is obtained as the speed vector of the ground speed V related to the true movement direction Dv of the underwater mobile body 4 as shown in FIG. It means a vector orthogonally projected in the direction Dd.

  Similarly, the obtained velocity vector of the velocity ve with respect to the signal arrival direction De of the underwater vehicle 4 is obtained as a signal of the velocity vector of the ground velocity V with respect to the true movement direction Dv of the underwater vehicle 4 as shown in FIG. It means a vector orthogonally projected in the arrival direction De.

  Therefore, as shown in FIG. 8, the virtual plane 18 perpendicular to the signal arrival direction Dc and the signal arrival direction of the underwater vehicle 4 at the position of the tip of the velocity vector of the velocity vc with respect to the signal arrival direction Dc of the underwater vehicle 4. At the position of the tip of the velocity vector of the velocity vd related to Dd, the virtual plane 19 perpendicular to the signal arrival direction Dd and the position of the tip of the velocity vector of the velocity ve related to the signal arrival direction De of the underwater mobile body 4 Is formed, the position of the tip of the velocity vector of the ground speed V in the moving direction Dv of the underwater vehicle 4 is located on the intersection 21 of the virtual plane 18, the virtual plane 19, and the virtual plane 20. become.

  Thereby, the speed measuring unit 12 can obtain the ground speed V of the underwater moving body 4 by obtaining the intersection 21 of the virtual plane 18, the virtual plane 19, and the virtual plane 20 by geometric calculation. it can.

  Therefore, in this embodiment, the speed measurement unit 12 can obtain the ground speed V of the underwater moving body 4 without receiving information on the moving direction Dv of the underwater moving body 4 from the detection device 13.

  Of course, the speed measurement unit 12 in the present embodiment may obtain the ground speed V of the underwater moving body 4 by the same processing as the speed measurement unit 12 in the first embodiment.

  The speed measurement system 1B of the present embodiment having the above configuration can be used in the same manner as the speed measurement system 1 of the first embodiment to obtain the same effect.

[Fourth Embodiment]
FIGS. 9A and 9B and FIGS. 10A, 10B, and 10C show a fourth embodiment of the speed measurement system.

  FIG. 9A is a diagram illustrating an example of a signal transmitted by the sound source device, and FIG. 9B is a diagram illustrating an example of a signal received by the receiving array of the underwater moving body. FIG. 10 shows the results of orthogonal detection processing on the signals received by the receiving array. FIGS. 10A, 10B, and 10C show the change in the distance between the underwater moving body and the sound source device. It is a figure which shows the result in different cases, respectively.

  The configuration of the speed measurement system 1 of the present embodiment is the same as that of the first embodiment shown in FIGS. 1A and 1B except for the function of the sound source device and the function of the second detection unit in the arithmetic device. It is.

  The sound source device 3 in the present embodiment has a function of transmitting a tone burst signal based on a sine wave having a constant frequency to the outside as an acoustic signal 22 from the transmission unit 8 as shown in FIG. The frequency of the acoustic signal 22 transmitted from the sound source device 3 is f0 [Hz].

  In addition, the sound source device 3 has a function of sequentially transmitting the acoustic signal 22 from the transmission unit 8 repeatedly at a set transmission interval.

  Therefore, in this embodiment, the receiving array 5 provided in the underwater moving body 4 sends the information of the acoustic signal 22 to the arithmetic device 6 as it is when the acoustic signal 22 is received by a plurality of hydrophones (not shown). The acoustic signal 22 received by the receiving array 5 is a tone burst signal as shown in FIG. 9B, but the frequency is different from that of the acoustic signal 22 transmitted from the sound source device 3. There is a case. The frequency of the acoustic signal 22 received by the receiving array 5 is f1 [Hz].

  When the second detection unit 11 of the arithmetic device 6 in the present embodiment receives the information of the received acoustic signal 22 from the receiving array 5, the velocity v related to the signal arrival direction D of the underwater moving body 4 by the following processing. It has the function to ask for.

  In the present embodiment, the second detection unit 11 stores in advance setting information of the frequency f0 [Hz] of the acoustic signal 22 transmitted from the sound source device 3.

  When the second detection unit 11 receives the information of the received acoustic signal 22 from the reception array 5, the second detection unit 11 performs a quadrature detection process using the setting information of the frequency f0 [Hz].

  When the quadrature detection process performed by the second detection unit 11 obtains a result that the phase θ [rad] takes a constant value along the time axis direction as shown in FIG. This is a state where f1 = f0, that is, a state where the Doppler effect is not acting. From this, it can be seen that the speed of the underwater vehicle 4 in the signal arrival direction D is zero. Therefore, in this case, it can be seen that the underwater vehicle 4 has not moved in the direction approaching the sound source device 3 and has not moved in the direction away from the sound source device 3.

  On the other hand, as a result of the quadrature detection process performed by the second detection unit 11, as shown in FIG. 10B, a change in which the value of the phase θ [rad] increases with time is periodically repeated. If the result is obtained, it can be seen that f1> f0. The increase in the frequency of the acoustic signal 22 from f0 to f1 is due to the Doppler effect. From this result, it can be seen that the underwater vehicle 4 is moving in the direction approaching the sound source device 3 with respect to the signal arrival direction D.

  Further, by measuring the slope (dθ / dt (> 0)) when the value of the phase θ [rad] increases, the frequency f1 of the acoustic signal 22 received by the receiving array 5 is obtained by the following equation: The speed at which the underwater vehicle 4 moves in the direction of approaching the sound source device 3 along the signal arrival direction D can be obtained.

ここで、ｃは水中での音速（１５００ｍ／ｓ）である。

Here, c is the speed of sound in water (1500 m / s).

  On the other hand, as a result of the quadrature detection process performed by the second detection unit 11, as illustrated in FIG. 10C, a result of periodically repeating a change in which the value of the phase θ [rad] decreases with the passage of time is obtained. When obtained, it can be seen that f1 <f0. The decrease in the frequency of the acoustic signal 22 from f0 to f1 is due to the Doppler effect. From this result, it can be seen that the underwater vehicle 4 is moving in the direction away from the sound source device 3 with respect to the signal arrival direction D.

  Further, by measuring the slope (dθ / dt (<0)) when the value of the phase θ [rad] decreases, the frequency f1 of the acoustic signal 22 received by the receiving array 5 is obtained by the same equation as above. While being able to obtain | require, the speed which the underwater moving body 4 moves to the direction which leaves | separates from the sound source device 3 along the signal arrival direction D can be calculated | required as a negative value regarding the speed which moves to the direction approaching the sound source device 3.

  Therefore, the second detection unit 11 is based on the relationship between the frequency f1 of the received acoustic signal 22 and the frequency f0 of the acoustic signal 22 at the time of transmission shown in FIG. And a function for obtaining the velocity v related to the signal arrival direction D of the underwater vehicle 4.

  Thus, in this embodiment, since the speed v regarding the signal arrival direction D of the underwater moving body 4 can be obtained by the second detection unit 11, the moving direction of the underwater moving body 4 is determined by the speed measuring unit 12. A speed vector of the ground speed V related to Dv can be obtained.

  Therefore, the speed measurement system 1 of the present embodiment can also measure the ground speed V related to the moving direction Dv of the underwater moving body 4 based on the processing by the arithmetic device 6, and the same effect as the first embodiment. Can be obtained.

  Note that the sound source device 3 that transmits the acoustic signal 22 and the second detection unit 11 of the arithmetic device 6 in the present embodiment may be applied to the first application example and the second application example of the first embodiment. Of course.

  Furthermore, the sound source device 3 that transmits the acoustic signal 22 in the present embodiment and the second detection unit 11 of the arithmetic device 6 are the speed measurement system 1A of the second embodiment and the speed measurement system 1B of the third embodiment. Of course, it may be applied to.

  The present invention is not limited to the above embodiments and application examples. Of course, the number of tone generators 3, 3a, 3b, 3c, 3d, 3e may be four or more.

  The arrangement of the sound source devices 3a and 3b in the second embodiment and the arrangement of the sound source devices 3c, 3d, and 3e in the third embodiment show examples of arrangements when a plurality of sound source devices are used. The arrangement of the apparatus may be set freely.

  The speed measurement unit 12 is based on the first detection unit 10, the second detection unit 11, and the information on the movement direction Dv of the underwater mobile unit 4 obtained from the detection device 13 as necessary. As long as the ground speed V can be calculated, the actual calculation method and calculation process may be set freely.

  The first detection unit 10, the second detection unit 11, and the speed measurement unit 12 in the arithmetic device 6 are only required to be included in the arithmetic device 6 as functions, and need not be independent components or devices. .

  The speed measurement system of the present invention may be applied to the measurement of the ground speed of the underwater moving body 4 that moves in the water other than the sea. In that case, what is necessary is just to read the sea area, the underwater, the sea surface, and the seabed 2 in description of each embodiment and each application example as a water area, underwater, a water surface, and a water bottom, respectively.

  Moreover, the underwater vehicle 4 that is the object of measurement of the ground speed V may be the underwater vehicle 4 used for any purpose other than exploration.

  Of course, various modifications can be made without departing from the scope of the present invention.

2 sea bottom (water bottom), 3, 3a, 3b, 3c, 3d, 3e 1 detection section, 11 second detection section, 12 speed measurement section, D, Da, Db, Dc, Dd, De signal arrival direction, V ground speed, v, va, vb, vc, vd, ve speed

Claims (4)

A sound source device installed at the bottom of the water,
A receiving array provided in the underwater vehicle;
Based on the information received from the receiving array, a calculation device for obtaining the ground speed of the underwater moving body,
The sound source device has a function of transmitting an acoustic signal obtained by connecting a waveform having only one peak in autocorrelation a plurality of times at a set time interval,
The arithmetic unit is
A first detector for obtaining a signal arrival direction in which the acoustic signal arrives based on information of the acoustic signal received by the receiving array;
A second detection unit for obtaining a speed of the underwater moving body related to the signal arrival direction based on the information of the acoustic signal received by the receiving array;
A speed measurement system comprising: a speed measurement unit that obtains a ground speed of the underwater moving body based on information received from the first detection unit and information received from the second detection unit. The sound source device is a plurality,
The speed measurement system according to claim 1, wherein each of the plurality of sound source devices has a function of transmitting the acoustic signals that can be distinguished from each other. The arithmetic unit is
A first detector that obtains a signal arrival direction in which each acoustic signal arrives based on information on each acoustic signal from each sound source device received by the receiving array;
A second detection unit that obtains a velocity of each underwater moving body with respect to each signal arrival direction based on information of each acoustic signal received from each sound source device received by the receiving array; 2. The speed measurement system according to 2. A step of transmitting an acoustic signal obtained by connecting a waveform having only one peak in autocorrelation at a set time interval from a sound source device installed at the bottom of the water;
Receiving the acoustic signal at a receiving array provided in the underwater vehicle;
Obtaining a signal arrival direction in which the acoustic signal arrives based on information of the acoustic signal received by the receiving array;
Obtaining a velocity of the underwater moving body related to the signal arrival direction based on information of the acoustic signal received by the receiving array;
Obtaining the ground speed of the underwater moving body based on information on the direction of arrival of the signal from which the acoustic signal arrives and information on the speed of the underwater moving body regarding the direction of arrival of the signal. Speed measurement method.

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