JP2004061178A - Position measuring system and position measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broader-based position measuring system which measures a self position in a wide range. <P>SOLUTION: The broader-based position measuring system is characterized by transmitting a sound wave signal of very low frequency, in a broader-based position measuring system which measures a position of an underwater object by using acoustics. The broader-based position measuring system is equipped with sound producing devices (pingers or transponders) 1-3 for transmitting the sound wave signals of very low frequency, echo sounder receivers 11 with filters which are installed in an AUV 10 and receive the respective sound wave signals transmitted from the sound producing devices 1-3, and an arithmetic operation section 103 which measures a position of the AUV 10, on the basis of the sound wave signal received by the echo sounder receiver 11 with filter. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wide-area position measurement system that measures the position of an underwater object using sound, and more particularly to a wide-area position measurement system that measures an underwater object using low-frequency sound waves.
[0002]
[Prior art]
Conventionally, in an underwater position measurement system, a positioning range of about 10 km is sufficient, in which case, a sound wave signal transmitted from one transponder (transmitter) is received by two receivers, The position of a submarine (underwater vehicle) was measured using the time difference between the two waves.
[0003]
Conventional systems are disclosed in an acoustic marker device of Japanese Patent Application Laid-Open No. 05-319376, an acoustic positioning device of Japanese Patent Application Laid-Open No. 05-302974, and in each of the three systems, three transponders are used. Sound waves (underwater sound waves) having different frequencies are transmitted from the transponder. The frequency employed in this system is a low frequency of about 500 Hz to 2 kHz in the former acoustic marking device, and 15 kHz, 16 kHz, and 17 kHz in the latter acoustic positioning device.
[0004]
Further, the latter acoustic positioning device specifies one of two positions simultaneously obtained from three transponders using a depth gauge, and the former acoustic marker device does not disclose measurement of depth.
[0005]
Underwater sound speed is about 1500 m / s, and it is known that sound waves are transmitted over long distances by using low-frequency sound waves in water. In a conventional system, for example, when a sound wave having a frequency of 5 kHz is transmitted, the wavelength is about 30 cm, and the phase difference between the two received waves is detected when the two receivers are separated by about 10 cm. And could calculate the angle between the transponder and the direction of travel of the submarine.
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional acoustic positioning device or the like, since the frequency is high or about 500 Hz even at a low frequency, sound waves cannot be transmitted over a long distance in water. There was a problem that it could not be used. In other words, underwater, the higher the frequency of the transmitted sound wave, the greater the attenuation during propagation, and the more likely it is to be affected by noise.Therefore, transmit the sound wave over a certain distance and receive it on the submarine. There was a problem that was difficult.
[0007]
In particular, an autonomous underwater vehicle (AUV: Autonomous Underwater Vehicle) for exploring the deep sea may travel a long distance in the deep sea, and there is a strong need for the construction of a system capable of position measurement over a wide area. For example, if the AUV attempts to cross the Arctic Ocean under the ice, the AUV must travel autonomously for a distance of several thousand kilometers, and as a position measurement system, transmit a distance of at least several thousand kilometers, It is necessary to use identifiable sound waves.
[0008]
In addition, in order to measure the position of a submarine over a wide area using low-frequency sound waves as the transmission waves transmitted from the transponders, the individual transponders must be arranged at a considerable distance from each other. In such a case, it is conceivable that the submarine can receive sound waves from only two transponders. In such a case, it is conceivable that the user's own position must be measured using a conventional inertial navigation system (INS).
[0009]
Furthermore, by using lower frequencies than the conventional device, the wavelength at each frequency becomes longer than in the case of the conventionally used frequency, so it is necessary to increase the interval between the plurality of receivers installed on the submarine. Also, there is a problem that the phase difference cannot be detected.
[0010]
Therefore, the present invention has been made in view of the above problems, and provides a wide-area position measurement system capable of measuring its own position in a wide area by using sound waves having a lower frequency than conventionally used. With the goal.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a wide-area position measurement system that measures a position by an underwater positioning method, transmitting an extremely low frequency sound wave signal into water and receiving the sound wave signal to perform position measurement. Is performed. By using an extremely low frequency sound wave signal as the transmission signal, the sound wave signal is less likely to be attenuated in water, so that the position of the object can be measured in a wide area. Here, in the present invention, the extremely low frequency sound wave signal is a sound wave signal in a frequency band of 20 to 300 Hz. Since the underwater sound wave has a characteristic that it propagates over a longer distance as its frequency is lower, this characteristic is applied to position measurement in the present invention.
[0012]
Further, in order to solve the above problems, a wide-area position measurement system according to the present invention is provided with a sounding device including a pinger or a transponder for transmitting a sound wave signal of an extremely low frequency, and provided on an underwater vehicle, and transmitted from each sounding device. Receiving means for receiving the respective sound wave signals to be transmitted, and position measuring means for measuring the position of the underwater vehicle based on the sound wave signals received by the receiving means.
[0013]
According to the present invention, the sounding device transmits an extremely low frequency sound wave signal, which is received by the underwater moving body by the receiving means of the underwater moving body, and the position of the underwater moving body is measured based on the received sound wave signal. The position of the underwater vehicle is measured by the means. Therefore, according to the present invention, the position of the underwater vehicle can be measured in a wide area.
[0014]
Here, the sound wave signal may be coded itself based on at least the identification signal, or the sound wave signal may be a carrier wave, and may be modulated to put at least the identification signal on the carrier wave. Is also good. At least the identification signal includes an identification signal of the sounding device, a transmission time, and the like. By using such an identification signal or the like, it is possible to specify which sounding device transmitted the message and when, and it is possible to measure the position of the underwater moving body together with the position information of the sounding device.
[0015]
Further, when the transmission time is coded, the transmission time can be specified by the received sound signal even if the time at which the sound signal is transmitted from the sound generator is not predetermined, and the reception time and the reception time can be specified. The distance from the sounding device to the underwater vehicle can be measured based on the time difference between the transmission times. If the identification signal is coded, even if the frequencies of the sound waves transmitted from the respective sound generating devices are the same, as long as they do not overlap, the sound signals are transmitted from any sound generating device. It can be determined whether the signal is a sound wave signal.
[0016]
Furthermore, the receiving means receives the sound wave signal transmitted from each sounding device a plurality of times, and the position measuring means averages position information data measured from each sound wave signal, The position may be measured. As a result, the influence of noise can be reduced, and more accurate position measurement can be performed.
[0017]
Further, the wide area position measuring method of the present invention is based on a step of transmitting an extremely low frequency sound wave signal from the sounding device, a step of receiving the sound wave signal transmitted from the sounding device, and a propagation time of the sound wave signal. Calculating the distance from each sounding device to the underwater vehicle, and based on the calculated respective distance data, or based on the respective distances and depth data obtained from a depth sensor of the underwater vehicle. And measuring the position of the underwater vehicle.
[0018]
Further, the wide area position measurement method may further include a step of repeating each of the steps a plurality of times and averaging the position data obtained in each of the position measurement steps. These wide-area position measurement methods have the same effects as the above-described wide-area position measurement system.
[0019]
Further, in order to solve the above-mentioned problem, a sound generating device according to the present invention transmits an extremely low frequency sound wave signal. The sound wave signal may be coded at least on the basis of the identification signal, and the sound wave signal may be a carrier wave, and may be modulated so that the carrier wave carries at least the identification signal.
[0020]
Next, in order to solve the above-described problem, the underwater vehicle angle measuring device of the present invention is provided in an underwater vehicle that receives a sound wave signal from at least one sound emitting device that transmits a very low frequency sound wave signal. An angle measuring device, based on a received first sound wave signal, first calculating means for calculating a distance between the sounding device and the underwater vehicle, and Second calculating means for calculating a distance between the sounding device and the underwater moving object based on the reception time of the first and second sound wave signals, and measuring a moving distance of the underwater moving object based on reception times of the first and second sound wave signals. Based on three distances obtained by the moving distance measuring means, the first and second calculating means, and the moving distance measuring means, an angle at which the sounding device is positioned with respect to the traveling direction of the underwater vehicle is calculated. Angle calculation means Characterized in that it obtain.
[0021]
According to the present invention, the distance between the sound generating device and the underwater vehicle at the position where the sound wave signal is received is calculated based on the first and second sound wave signals, and based on the reception times of the two sound wave signals. Then, the distance that the underwater vehicle has moved during that time is measured, and the angle at which the sound generating device is positioned with respect to the traveling direction of the underwater vehicle is calculated using these three distances.
[0022]
Therefore, by using the distance between the underwater vehicle and the three sides of the triangle created by the sound generator, the angle at which the sound generator is located with respect to the traveling direction of the underwater vehicle can be calculated, and the depth sensor provided in the underwater vehicle. The position of the underwater vehicle can be measured based on the output and the angle. Also, by using the moving distance of the underwater vehicle itself, the position of the underwater vehicle can be specified without receiving a plurality of receivers for receiving the sound wave signal and detecting the angle from the phase difference. Can be.
[0023]
Here, the angle calculating means may calculate the angle using the cosine theorem when three sides of the triangle are known.
[0024]
Further, the angle measurement method for an underwater vehicle according to the present invention includes an underwater vehicle that measures an angle between the underwater vehicle that receives a sound wave signal from at least one sounding device that transmits an extremely low frequency sound wave signal and the sounding device. A body angle measurement method, based on a received first sound wave signal, calculating a distance between the sounding device and the underwater vehicle, and based on a received second sound wave signal, Calculating a distance between the sounding device and the underwater vehicle; measuring a movement distance of the underwater vehicle based on reception times of the first and second sound signals; Calculating the angle at which the sounding device is located with respect to the traveling direction of the underwater vehicle based on the three distances obtained in (1).
[0025]
Here, in the angle calculation step, the angle may be calculated using a cosine theorem in a case where three sides of the triangle are known.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a wide-area position measurement system according to the present invention will be described in detail with reference to FIGS. This embodiment is given as an example, and the present invention should not be construed as being limited thereto.
[0027]
(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic layout diagram of the wide area position measurement system according to the first embodiment of the present invention. In FIG. 1, the wide-area position measuring system includes an AUV 10, three sounding devices (pingers or transponders; the same applies hereinafter) 1, 2, and 3, and the AUV 10 has one filter for receiving a signal from each sounding device. A wave receiver 11 is provided.
[0028]
The sounding devices 1 to 3 are disposed at a depth of about 100 m from the sea floor, or with anchors lowered from the sea surface, or fixed to the bottom of the bus bar, and generate sound waves (underwater sound waves) having different frequencies. And send it. All of the sound generating devices 1 to 3 are synchronized at the time of installation, and all generate sound wave signals at the same time or with a predetermined time shift as needed, for example, using an atomic clock.
The synchronization method is a well-known ocean acoustic tomography technology (ocean acoustic tomography uses a sound wave to instantaneously know the state of the sea about three times the total area of the land in Japan. This is possible by using a photographing device. Note that the sound generation devices 1 to 3 and the timer unit 104 of the AUV 10 described later are synchronized in advance.
[0029]
For example, considering the case where an AUV crosses the Arctic Ocean, sounding devices are appropriately spaced around the Arctic Ocean.
[0030]
The frequency of the underwater sound wave transmitted from these sounding devices is lower than usual or conventionally used, and actually, a sound wave having a frequency of about 50 Hz to 200 Hz is used. By using the marine acoustic tomography technique, it is possible to transmit a distance of about 500 km at a frequency of 200 Hz and 1000 km or more at 100 Hz in water. When the frequency of the sound wave is 50 Hz, the sound wave can propagate over a distance of about several thousand km.
[0031]
Next, a method of position measurement in AUV will be described with reference to FIG. FIG. 2 is a block diagram illustrating processing of a sound wave received by the AUV 10 according to the first embodiment of the present invention. 2, the signal processing unit 100 includes a wave receiving unit 101, an amplifying unit 102, an arithmetic processing unit 103, and a timer unit 104. Although not shown, the signal processing unit 100 may be connected to a battery and further include a display unit and the like. The timer unit 104 includes an atomic clock.
[0032]
Further, the arithmetic processing unit 103 includes a storage unit that stores an application program used by a computer for executing various processes. This storage unit stores coordinate data (longitude, latitude, and depth) of each sounding device in advance. It is used to store the position information obtained by the arithmetic processing described later as needed. Further, the arithmetic processing unit 103 receives depth information from a depth sensor (not shown) that measures the depth of the AUV 10, and calculates a current position based on the information and the arithmetically processed longitude and latitude information.
[0033]
FIG. 3 is a diagram illustrating functional blocks of the arithmetic processing unit 103 according to the first embodiment of the present invention. In FIG. 3, the arithmetic processing unit 103 includes a sounding device-underwater moving body distance calculating unit 1031, a three-point positioning unit 1032, a depth detecting unit 1033, and a position measuring unit 1034. In the present embodiment, the sounding device-underwater moving body distance calculating means 1031 calculates the distance between the three sounding devices 1 to 3 and the AUV 10, and based on the calculation result, the three-point positioning means 1032 generates the AUV 10 And the depth detecting means 1033 detects the depth of the AUV 10 and corrects the specified position data (determines on which side of the plane including the three points the AUV 10 is located).
[0034]
Next, the operation of the present invention will be described with reference to FIG. FIG. 4 is a flowchart of the position measurement processing of the AUV 10 according to the first embodiment of the present invention. When the sound wave signals are transmitted from the three sounding devices 1 to 3 (step S1), the AUV 10 receives the sound wave signals transmitted from the sound generating devices 1 to 3 by the filter-equipped receiver 11 (step S2). At this time, the sound wave signals received by the receivers 11 to 13 are output to the receiver 101, amplified by the amplifier 102, and input to the arithmetic processor 103.
[0035]
In the arithmetic processing unit 103, the coded information is extracted from the coded sound wave itself or coded on the carrier wave of the input sound wave signal. This coded information includes at least the identification signal and the transmission time. The identification signal information indicates from which sound generator the sound wave signal is transmitted, and is used to prevent the frequency of the received sound wave signal from being erroneously recognized due to attenuation or influence of noise during propagation. By including the transmission time information, it is possible to calculate the propagation time of the sound wave signal without generating a sound wave signal from the sound generating device at a fixed time.
[0036]
The arithmetic processing unit 103 uses the difference between the transmission time obtained from the information encoded on the carrier wave and the reception time of the atomic clock in the timer unit 104 as the propagation time, and sets the sound speed in water (about 1500 m / s). Then, the distance (propagation distance) from the AUV 10 to each of the sound generating devices 1 to 3 is calculated (step S3).
[0037]
The arithmetic processing unit 103 measures the current position of the AUV 10 in a wide area based on the distance from the three sounding devices 1 to 3 to the AUV 10 and depth data obtained from a depth sensor (not shown) (step S4). However, since the influence of noise and the like can be considered, in order to reduce the influence, the wide-area position measurement system according to the present invention may perform averaging processing based on a plurality of calculations. In this case, the calculation result of each time is temporarily stored in a storage unit in the calculation processing unit 103, and after all position measurements are performed, the calculation processing unit 103 determines the longitude, latitude, and longitude of the calculation result (position information). The current position is specified by averaging the depths (step S5). Then, the arithmetic processing unit 103 stores the specified current position data in the storage unit (Step S6).
[0038]
As described above, in the wide-area position measurement system according to Embodiment 1 of the present invention, the frequency of the sound wave signal transmitted from the plurality of sounding devices 1 to 3 is lower than that of the related art, that is, approximately 50 to 200 Hz. The identification signal and the transmission time information are coded on the carrier of the sound wave signal.
[0039]
Therefore, the transmitted acoustic wave signal can propagate over a long distance of several thousand km, so that the AUV 10 can receive the acoustic wave signal in a wider area (wider area) than in the past, and can determine its position in a wider area. It is possible to measure.
[0040]
Further, in the wide-area position measurement system of the present invention, since the identification signal and the like are encoded on the carrier wave, the current position of the AUV 10 can be measured without generating a sound wave signal at a predetermined time.
[0041]
In this embodiment, three sounding devices 1 to 3 are used, but it goes without saying that four or more sounding devices may be used.
[0042]
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a schematic explanatory diagram of an angle measurement device for the AUV 10 sound generation device according to Embodiment 2 of the present invention. In FIG. 5, three AUVs 10 are shown, but those indicated by broken lines indicate imaginary positions, and the others indicate the positions of the AUVs 10 before and after the lapse of a predetermined time. As can be seen, the AUV 10 travels from left to right in the figure.
[0043]
Since the frequency of the sound wave signals transmitted from the sound emitting devices 1 to 3 is extremely low, 50 to 200 Hz, the sound wave signals from one sound emitting device cannot be received by a plurality of receivers with an appropriate phase difference. Therefore, in the present embodiment, the angle at which the sound generating device is positioned with respect to the traveling direction of the AUV 10 is measured by treating one receiver as a plurality of receivers by the AUV 10 traveling by itself.
[0044]
Note that a block diagram showing the processing of the sound wave signal received by the AUV 10 is the same as that of the first embodiment, and is not shown in this embodiment, and will be described using the reference numerals in FIG. 2 if necessary. I do. FIG. 6 is a diagram showing functional blocks of the arithmetic processing unit 103 according to Embodiment 2 of the present invention. 6, the arithmetic processing unit 103 includes a sounding device 1-underwater moving body distance calculating unit 1035, an underwater moving body moving distance detecting unit 1036, a sounding device 2-underwater moving body distance calculating unit 1037, Device angle measuring means 1038.
[0045]
Returning to FIG. 5, the arrangement of the AUV 10 and the sound generating device 1 will be described. The sounding device 1 (and 2) transmits sound wave signals at regular intervals. Then, the AUV 10 first receives, via the filter-equipped receiver 11, the sound wave signal transmitted from the sound generator 1 at the first position of the AUV 10 (solid line on the left side in the figure). The propagation distance at this time is l₂+ L₄Indicated by Next, the AUV 10 receives a sound wave signal from the sound generating device 1 again at a position on the right side of the figure after a predetermined time has elapsed. The propagation distance at this time is l₃Indicated by Here, since the AUV 10 includes the above-described INS, the AUV 10 can measure its own moving distance from the first reception of a sound wave signal to the next reception thereof. In this figure, the moving distance of the AUV 10 in the meantime is l₁Indicated by Also, the angle between the traveling direction of the AUV 10 and the sound generating devices 1 and 2 at the initial position is α₁₁And α₁₂And at the next position,₂₁And α₂₂It is.
[0046]
As in the first embodiment, all of the sound generators 1 and 2 (only two are shown in FIG. 5) and the AUV 10 are synchronized (with a built-in synchronization clock), and the storage unit (not shown) of the AUV 10 Position information (longitude and latitude) and depth information of the sounding devices 1 and 2 on the earth are stored in advance.
[0047]
Information such as an identification signal, a transmission frequency, and a transmission time is coded in the sound wave signal. For this reason, the distance between the sound generator and the AUV 10 (in FIG. 5, l is shown in FIG. 5) based on the time at which the sound signal was received by the AUV 10 and the coded transmission time.₂+ L₄And l₃) Is calculated. The AUV 10 has a distance l between the first reception of a sound wave signal and the next reception thereof.₁Just move. This distance and the moving direction of the AUV 10 are measured by INS provided in the AUV 10. Further, the depth of the AUV 10 is measured by a depth sensor (not shown).
[0048]
One angle measuring method according to the present embodiment applies the cosine theorem to a triangle connecting the two AUVs 10 and the sound generating device 1 in FIG.₁₁Is to seek. That is, in this method, the length of three sides is l₁, L₂+ L₄, L₃In the triangle of cosα₁₁= ｛L₁ ²+ (L₂+ L₄)²−l₃ ²｝ / 2 * l₁* (L₂+ L₄) Is substituted for three known distances, and the angle α₁₁Is calculated. Where angle α₁₁Has an imaginary position, the angle α calculated from the sound generator 2₁₂, The actual position can be specified. It is also possible to calculate the actual position by changing the needle of the AUV 10.
[0049]
Next, the operation of the present invention will be described with reference to FIG. FIG. 7 is a flowchart of the angle measurement processing of the position of the sound generation device with respect to the traveling direction of the AUV 10 according to the second embodiment of the present invention. When receiving the first sound wave signal transmitted from the sound generating device via the receiver with filter 11 (step S11), the arithmetic processing unit 103 extracts the transmission time encoded in the received sound wave signal, and The propagation time is calculated by comparing with the time, and the first propagation distance is calculated based on the propagation time (step S12).
[0050]
Subsequently, after the AUV 10 has moved for a predetermined time, a second sound wave signal is received (step S13), and a second propagation distance is similarly calculated (step S14). At this time, the time between receiving the first and second sound wave signals is measured by the timer 14 (step S15), and the self-propelled distance traveled by the AUV 10 during that time is calculated using INS (step S16).
[0051]
Based on the three distances thus obtained, the angle of the sound generator with respect to the traveling direction of the AUV 10 is calculated by using any of the above-described methods (step S17), and the calculated angle data is not shown. It is stored in the storage unit (step S18).
[0052]
When the angle of the sounding device with respect to the traveling direction of the AUV 10 is calculated in this way, the position information (longitude, latitude, and depth) of each sounding device stored in a storage unit (not shown) in the arithmetic processing unit 103 and this The current position of the AUV 10 can be calculated from the angle, and this step may be added to the present invention.
[0053]
As described above, in the angle measuring device according to the second embodiment of the present invention, the frequency of the sound wave signal transmitted from the sound generating devices 1 and 2 is lower than that of the related art by about 50 to 200 Hz. The identification signal, the transmission frequency, and the information of the transmission time are coded on the carrier of the signal, and the AUV 10 receives the sound wave signal twice, and calculates the distance between the sound source and the moving distance of the AUV 10 between the received points. By calculating, the angle of the sound generating device with respect to the traveling direction of the AUV 10 is measured.
[0054]
Therefore, even when the sound wave signal has a low frequency, the angle of the sound generating device with respect to the traveling direction of the AUV 10 is measured without providing two or more receivers in the AUV 10 and measuring the phase difference of the sound wave signal transmitted. Can be. When the position of each sounding device is stored in the storage unit of the AUV 10 in advance, the position of the AUV 10 can be specified by the coordinates, the measured angle, and the depth obtained by the depth sensor.
[0055]
【The invention's effect】
As described above, according to the present invention, since an extremely low frequency is used as the transmission frequency of the sound generating device, the underwater vehicle can receive a transmission signal even at a long distance, so that the position can be measured in a wide area. . Further, since the identification signal or the like is encoded in the transmission signal, each sound generation device can be identified even if the transmission frequency is the same.
[Brief description of the drawings]
FIG. 1 is a schematic layout diagram of a wide-area position measurement system according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram illustrating processing of a sound wave signal received by AUV according to Embodiment 1 of the present invention.
FIG. 3 is a diagram showing functional blocks of an arithmetic processing unit according to the first embodiment of the present invention.
FIG. 4 is a flowchart of an AUV position measurement process according to the first embodiment of the present invention.
FIG. 5 is a schematic explanatory diagram of an angle measuring device for an AUV sound generating device according to Embodiment 2 of the present invention.
FIG. 6 is a diagram showing functional blocks of an arithmetic processing unit according to Embodiment 2 of the present invention.
FIG. 7 is a flowchart of an angle measurement process of the position of the sound generation device with respect to the AUV traveling direction according to the second embodiment of the present invention.
[Explanation of symbols]
1,2,3 sound generator
10 AUV
11 Receiver with filter
101 receiving part
102 amplifier
103 arithmetic processing unit
104 Timer section

Claims (14)

In a wide-area position measurement system that measures position by underwater positioning method,
A position measurement system that transmits an extremely low frequency sound wave signal into water and receives the sound wave signal to perform position measurement. A sounding device including a pinger or transponder for transmitting an extremely low frequency sound wave signal in water,
Receiving means provided on the underwater vehicle, for receiving each sound wave signal transmitted from each sounding device,
Position measuring means for measuring the position of the underwater vehicle based on the sound wave signal received by the receiving means,
A position measuring system comprising: The position measurement system according to claim 1, wherein the sound wave signal is coded based on at least an identification signal. The position measurement system according to claim 1, wherein the sound wave signal is a carrier wave, and the carrier wave is modulated at least to carry an identification signal. The receiving means receives the sound wave signal transmitted from each sounding device a plurality of times, and the position measuring means averages position information data measured from each sound wave signal to determine a current position. The position measurement system according to claim 1, wherein measurement is performed. Transmitting an extremely low frequency sound wave signal from the sounding device into the water;
Receiving a sound wave signal transmitted from the sounding device;
Based on the propagation time of the sound wave signal, calculating the distance from each sounding device to the underwater vehicle,
Measuring the position of the underwater vehicle based on the calculated respective distance data or based on the respective distances and depth data obtained from a depth sensor of the underwater vehicle,
A position measuring method comprising: The position measuring method according to claim 6, further comprising the step of repeating each of the steps a plurality of times and averaging the position data obtained in each of the position measuring steps. A sound producing device for transmitting an extremely low frequency sound wave signal into water. The sound generating device according to claim 8, wherein the sound wave signal is coded at least based on at least an identification signal. 9. The sound generating device according to claim 8, wherein the sound wave signal is a carrier wave, and the carrier wave is modulated to carry at least an identification signal. An angle measurement device provided in an underwater vehicle that receives a sound wave signal from at least one sound generating device that transmits an extremely low frequency sound wave signal in water,
First calculating means for calculating a distance between the sounding device and the underwater vehicle based on the received first sound wave signal;
Second calculating means for calculating a distance between the sounding device and the underwater vehicle based on the received second sound wave signal;
Moving distance measuring means for measuring a moving distance of the underwater vehicle based on reception times of the first and second sound wave signals;
An angle calculation unit that calculates an angle at which the sounding device is positioned with respect to a traveling direction of the underwater vehicle based on the three distances obtained by the first and second calculation units and a movement distance measurement unit;
An angle measuring device for an underwater vehicle, comprising: The angle measuring device of the underwater vehicle according to claim 11, wherein the angle calculating means calculates the angle using a cosine theorem when three sides of the triangle are known. An angle measurement method for an underwater vehicle that measures an angle between an underwater vehicle and an acoustic device that receives an acoustic signal from at least one sounding device that transmits an extremely low-frequency acoustic signal,
Calculating a distance between the sounding device and the underwater vehicle based on the received first sound wave signal;
Calculating a distance between the sounding device and the underwater vehicle based on the received second sound wave signal;
Measuring the moving distance of the underwater vehicle based on the reception times of the first and second sound wave signals;
Calculating an angle at which the sounding device is positioned with respect to a traveling direction of the underwater vehicle based on the three distances obtained in each of the steps;
An angle measurement method for an underwater vehicle, comprising: 14. The angle measuring method for an underwater vehicle according to claim 13, wherein in the angle calculating step, the angle is calculated using a cosine theorem when three sides of the triangle are known.

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