JP2009162498A - Survey/classification method and device for object under water bottom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To survey an object under the water bottom, and simultaneously to perform classification by its material or the like. <P>SOLUTION: An under water sailing body 1 is loaded with a low-frequency sound source 2 for transmitting a wave having a low frequency obtained by changing a frequency over a required band width, a receiver 3 for receiving a low-frequency scattered wave 9 by a survey target object 7, a signal processor 5 for analyzing the scattered wave 9 received by the receiver 3, and a navigation device 6, to thereby form a survey/classification device for the object under the water bottom. By the signal processor 5, a frequency pattern of the low-frequency wave received by the receiver 3 is collated with a database wherein a frequency pattern of the scattered wave obtained from an object whose shape, size, material plate thickness or the like are known beforehand is accumulated, to thereby detect the survey target object which is an artificial object buried under the water bottom, and to classify its shape, size or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an underfloor object exploration classification method and apparatus used for classifying the shape, size, and the like of an object buried under a water bottom.

  Conventionally, as a means for measuring the size and shape of an object existing in water or at the bottom of the water, exploration using an acoustic image has been widely used.

  This is because a high frequency of several tens to several hundreds kHz from a transmitter (sound wave source) is converged into a highly directional beam, irradiated onto the object, reflected from the object, and placed at the same position as the sound wave source. By receiving the reflected wave returning at the receiver, the distance to the reflection point is measured based on the time information required from the irradiation of the high frequency by the transmitter to the reception of the reflected wave by the receiver, By accumulating a large number of position information of this reflection point, it is possible to create an audio image, search for an object existing in the water or the bottom of the water, and obtain information about the size and shape of the object visually. Has been.

  By the way, there is a case where an object such as an artificial object buried in a solid part such as sand, mud, gravel or the like under the water bottom is required.

  However, since the high frequency of several tens to several hundreds of kHz has a characteristic that it does not easily penetrate below the bottom of the water, it is difficult to search for an object buried under the bottom of the water using the conventional acoustic image exploration technique. Moreover, the obtained audio image is noisy and it is difficult to determine the shape of the object. Therefore, it is difficult to detect an object under the water bottom.

  On the other hand, in view of the fact that the low frequency has the characteristic of being easily transmitted under the bottom of the water, the low frequency is irradiated from the transmitter toward the bottom of the water and reflected from the object buried under the bottom of the water. When a wave is received by a receiver, an object buried in the bottom of the water based on the time information required from the low-frequency irradiation by the transmitter to the reception of the reflected wave by the receiver as described above Conventionally, a method for performing a search for the above has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  However, since the low frequency has a large wavelength, the resolution decreases. Therefore, in the conventional method for searching an object under the seabed, there is a problem that it is difficult to visually grasp the shape of the object to be searched like an acoustic image obtained when using the high frequency.

  Therefore, as a technique for enabling the discovery of an underwater resource (object) having a desired shape regardless of the shape or the state of being buried in the bottom of the water, the applicant of the present application Irradiate and receive scattered waves from unknown underwater resources at multiple locations around the exploration direction, arrival time of scattered waves received by multistatic measurement at these multiple locations, scattered wave reception level and scattering An underwater resource exploration method for estimating the location of an unknown underwater resource that causes the scattering and the shape and attitude of the underwater resource based on the pattern is proposed. Furthermore, it has also been proposed to use a low frequency of 20 kHz or less as the sound wave (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 4-13988 JP 2002-31136 A JP 2004-184268 A

  However, when searching for an object buried in the bottom of the water, especially when the object to be searched is made of an artificial elastic object, it has a natural vibration depending on its shape, size, material, and thickness, or It has the characteristic that the level of the scattered wave becomes very high with respect to the sound wave of a specific frequency.

  By using this characteristic, it is easy to distinguish an artifact, and by collating it with a database that stores the frequency pattern of scattered waves, the work efficiency of exploration and classification work can be greatly increased. It is considered to be.

  Therefore, the present invention improves the work efficiency of the exploration and classification work by using the scattered wave frequency pattern for the artificial elastic object in addition to the exploration of the underwater object and the detection of the shape of the underwater object. It is an object of the present invention to provide a submarine object exploration classification method and apparatus that can be greatly enhanced.

  In order to solve the above-mentioned problem, the present invention requires a frequency from the transmitter in the traveling body including a transmitter, a receiver, and a navigation device to a submerged object. The low frequency changed in the frequency band is transmitted, the low frequency scattered wave by the low frequency underwater object is received by the receiver, and the scattering received by the receiver is received. By comparing the frequency pattern of waves with a database in which the frequency patterns of scattered waves from objects with known shapes, sizes, materials, and plate thicknesses are stored in advance, the detection target object and its shape and size are detected. This is a method for classifying under-floor objects to be classified.

  Further, in accordance with claim 2, a low-frequency wave having a frequency changed in a required band is transmitted from the above-mentioned transmitter in the traveling body including the transmitter and the navigation device to the object under the seabed, The low-frequency scattered wave from the low-frequency underwater object is received by a receiver in a traveling body equipped with a receiver and a navigation device, and the scattered wave received by the receiver. By comparing the frequency pattern with a database in which the frequency patterns of scattered waves from objects with known shapes, sizes, materials, and thicknesses are stored in advance, the detection target object and its shape and size are detected. This is a method for searching and classifying objects under the bottom of the sea so as to classify the objects.

  Furthermore, in each of the above-described configurations, as a low frequency transmitted from the transmitter, a pulse wave having a slightly different frequency is transmitted by a low frequency or frequency modulation so as to cover a bandwidth of 20 kilohertz or less. A low frequency that transmits a pulse wave having a certain frequency bandwidth so as to cover a bandwidth of 20 kilohertz or less is used.

  Corresponding to claim 4, a transmitter and a receiver for transmitting a low frequency whose frequency is changed in a required band are mounted on a water or underwater vehicle equipped with a navigation device. In addition, the frequency pattern received by the receiver in a state where the low frequency transmitted from the transmitter is scattered by the object under the bottom of the water, an object whose shape, size, material, and plate thickness are known in advance. Compared with a database in which frequency patterns of scattered waves are stored, detection of the object to be probed, and analysis means that classifies its shape, size, etc. It is an exploration classification device.

  Further, in the above configuration, the transmitter and the receiver are individually mounted on a traveling body provided with a navigation device.

According to the present invention, the following excellent effects are exhibited.
(1) From the above-mentioned transmitter in a traveling body equipped with a transmitter, a receiver, and a navigation device, a low frequency whose frequency is changed in a required band is transmitted to an object under the seabed. The low-frequency scattered wave from the underwater object is received by the receiver, and the frequency pattern of the scattered wave received by the receiver has a shape, size, material, and plate thickness in advance. An under-floor object search classification method for detecting a target object and classifying its shape, size, etc. by collating it with a database in which frequency patterns of scattered waves from known objects are stored, and Since it is an apparatus, it is possible to detect the presence of an exploration target object that is an artificial object existing under the water bottom, and to further classify the shape, size, and the like of the exploration target object. In particular, when an object is made of an artificial elastic object, it uses natural vibration according to shape, size, material, and plate thickness, and collates with a database that stores scattered wave frequency patterns. By doing so, it becomes easy to distinguish the artifact, and the work efficiency of the exploration and classification work can be greatly increased.
(2) From the above-mentioned transmitter in a traveling body equipped with a transmitter and a navigation device, a low-frequency wave whose frequency is changed in a predetermined band is transmitted to an underwater object, and the underwater object of the low frequency is transmitted. The low-frequency scattered wave by the receiver is received by a receiver in a traveling body equipped with a receiver and a navigation device, and the frequency pattern of the scattered wave received by the receiver is shaped in advance. Detecting the object to be searched and classifying its shape, size, etc. by collating it with a database that stores frequency patterns of scattered waves from objects with known size, material, and plate thickness By using the underfloor object search method and apparatus, the positional relationship between the transducer and the underwater object in the sea can be set freely. Therefore, by sending a wave in a state where the underwater vehicle is traveling around the underwater object, the direction of the scattered wave level due to the shape and posture of the underwater object is found, The scattered wave can be measured in the direction in which the level of the scattered wave is high. In addition, a plurality of navigation bodies equipped with a receiver and a navigation device are prepared and arranged so as to surround the underwater object to be explored. A low-frequency wave is transmitted from the transmitter in the middle-running vehicle, and a scattered wave of the low-frequency underwater object to be searched is arranged so as to surround the underwater object to be searched. It is possible to receive the waves with the receivers of the plurality of underwater vehicles. For this reason, it becomes possible to detect the scattered wave of the underwater object to be searched at a high level regardless of the shape and posture of the underwater object to be searched, and to analyze the frequency pattern of the scattered wave. Can be performed satisfactorily.
(3) Low frequency that is transmitted from the transmitter as a low frequency, a pulse wave that is slightly different in frequency so as to cover a bandwidth of 20 kilohertz or less, or a certain frequency by frequency modulation By using a low frequency that transmits a pulse wave having a bandwidth so as to cover a bandwidth of 20 kilohertz or less, a scattered wave caused by a submerged object as shown in the above (1) and (2) The frequency pattern can be easily obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 to FIG. 3 show a method and apparatus for searching for underwater objects according to the present invention, which are configured as follows.

  That is, as shown in FIGS. 1 and 2, the underfloor object exploration classification apparatus according to the present invention includes an underwater vehicle 1 as a navigation vehicle, a low-frequency sound source 2 as a transmitter, and a receiver 3. And an amplifier 4 for amplifying the signal received by the receiver 3 and a signal processor 5 as analysis means for analyzing the received signal amplified by the amplifier. Further, the underwater vehicle 1 includes a navigation device 6 that can identify the positional relationship between its own position and the object 7 to be searched.

  More specifically, the low frequency sound source 2 can transmit a low frequency changed with a required bandwidth as a directional beam 8. Specifically, the low-frequency sound source 2 transmits, for example, pulse waves having slightly different frequencies so as to cover the entire range of the required bandwidth, or a certain frequency by frequency modulation. The configuration has a function of transmitting a pulse wave having a bandwidth so as to cover the entire area of the required bandwidth. The required band of the low frequency is 20 kHz or less, for example, a frequency band of several kilohertz to tens of kilohertz.

  The receiver 3 can detect the scattered wave 9 when the low frequency transmitted from the low frequency sound source 2 hits a desired object below the bottom of the water and scatters.

  The signal processor 5 has a function of detecting the search target object 7 and classifying the detected search target object 7 based on the frequency pattern of the scattered wave 9 received by the receiver 3. is there.

  Here, the principle of the detection target object 7 in the signal processor 5 and the classification method will be described.

  When a low-frequency wave that is easily transmitted through the bottom of the water from the low-frequency sound source 2 is transmitted to the underwater object, and the scattered wave 9 is received by the receiver 3 and measured, the underwater object is a hollow elastic body. 3 has a natural vibration, for example, a scattered wave (line A) by a hollow cylindrical elastic body closed at both ends as shown in FIG. 3 and a scattered wave by a rigid object of the same shape as shown in FIG. As is clear from comparison with (Line B), it has a characteristic that the level of the scattered wave becomes very high with respect to a sound wave of a specific frequency.

  Since such a phenomenon does not occur in naturally existing objects such as rocks and stones under the water bottom, it is possible to identify that the object under the water bottom is an artificial object by using the above characteristics.

  Furthermore, when the object under the seabed is an elastic body such as metal or FRP, the level of the scattered wave at a specific frequency increases or decreases depending on the shape, size, material, thickness, etc. of the object. Or

  Therefore, for various objects with known shapes, sizes, materials, plate thicknesses, etc., a pattern for the frequency of scattered waves for low frequencies within the required bandwidth range is obtained in advance by database measurement and numerical calculation. When the unknown object 7 to be detected is transmitted at a frequency lower than that of the low-frequency sound source 2 while changing the frequency within the required bandwidth, the receiver 3 receives the wave. The frequency pattern of the scattered wave 9 is compared with the frequency pattern of the scattered wave for the various objects stored in the database, and a frequency pattern that matches well is detected. The shape, size, etc. can be classified. Further, when there is no frequency pattern that matches well in the database, the shape, size, etc. of the unknown exploration target object 7 may be obtained approximately based on the data of the close frequency pattern.

  Further, as shown in Patent Document 1, depending on the shape and posture of the search target object 7 below the bottom of the water, even if a low frequency is transmitted to the search target object 7 from a certain direction, the search is performed. In some cases, the scattered wave from the target object 7 is difficult to return in the direction in which the low-frequency wave is transmitted. In view of this point, the underfloor object exploration classification apparatus according to the present invention transmits a low frequency from the low-frequency sound source 2 to the exploration target object 7 in order to increase the measurement accuracy of the scattered wave frequency pattern of the exploration target object 7. The scattered wave 9 is received by the receiver 3, the level of the scattered wave with respect to the frequency is recorded by the signal processor 5, and this operation is relative to the object to be searched 7 of the underwater vehicle 1. Based on the frequency pattern of the scattered wave 9 measured when the underwater vehicle 1 is arranged in a direction in which the return of the scattered wave is strong, A comparison is made.

  In the above description, the underwater vehicle 1 is used as the vehicle on which the low frequency sound source 2 and the receiver 3 are mounted. The underwater vehicle 1 is not easily affected by disturbances such as wind waves. This is because having the navigation device has the advantage of easily specifying the position.

  When using the underfloor object exploration classification device having the above configuration, the frequency is changed in the required bandwidth from the low-frequency sound source 2 mounted on the underwater vehicle 1 in the required direction. Transmit low frequency. At this time, if a specific frequency pattern is detected by the signal processor 5 in the transmitted low-frequency scattered wave 9 measured by the receiver 3, the transmission of the low-frequency sound source 2 is performed. It is detected that the search target object 7 that is an artificial object exists in the wave direction.

  Furthermore, the navigation device 6 of the underwater vehicle 1 specifies the positional relationship between the low frequency sound source 2 and the receiver 3 of the underwater vehicle 1 and the exploration target object 7 which is an artificial object whose presence has been detected. Under the condition, the frequency pattern of the scattered wave 9 by the search object 7 received by the receiver 3 by the signal processor 5 is collated with the database, so that the shape of the search object 7 Size etc. come to be classified.

  As described above, according to the submarine object search method and apparatus of the present invention, in addition to the detection of the presence of the exploration target object 1 which is an artificial object existing under the water bottom, the shape and size of the exploration target object 1 are determined. Etc. can be classified.

  In the above, for an object whose shape, size, material, thickness, etc. are known, a frequency pattern within the required bandwidth range as shown by line A in FIG. By identifying the frequency pattern within the required bandwidth range similar to the above obtained for the object 7 with the database, the shape, size, material, plate thickness, etc. of the object 7 to be searched are identified. As described above, in order to improve the signal-to-noise ratio of the signal of the scattered wave 9 received by the receiver 3, the level of the scattered wave increases according to the shape, size, material, plate thickness, etc. of the object. For an object to be probed that obtains a specific frequency, for example, the frequency pattern of line A in FIG. 3, the frequency in the region C in FIG. 1 to send to the object 7 The level of the scattered wave 9 that is scattered by the search target object 7 and received by the receiver 3 is the same as that of the receiver 3 after the low frequency transmitted from the low frequency sound source 2 is scattered by the search target object 7. A determination may be made as to whether or not the level is higher than the level assumed in the case of attenuation due to the propagation until the return to.

  The present invention is not limited to the above embodiment, and the signal processor 5 mounted on the underwater vehicle 1 analyzes the frequency pattern of the scattered wave 9 received by the receiver 3. Instead of classifying the shape, size, etc. of the object 7 to be searched based on the data, the scattered wave 9 data received by the receiver 3 is provided on a ship such as the mother ship of the underwater vehicle 1. To the analysis device provided on the ground or the analysis device provided on the ground, the analysis device provided on the ship, or the analysis device provided on the ground, the analysis of the frequency pattern of the scattered wave and the search object 7 based on the analysis Classification such as shape and size may be performed.

  A low-frequency transmission in which the frequency is changed within a predetermined band from the low-frequency sound source 2 while the underwater vehicle 1 travels around the object 7 to be searched, and the object to be searched By receiving the scattered wave 9 by 1 at the receiver 3, a direction in which the level of the scattered wave is high due to the shape and orientation of the object 7 to be searched is found, and the water in the direction where the level of the scattered wave is high You may make it perform the measurement of the scattered wave in the state which has arranged the middle traveling body 1. FIG. Further, separately from the underwater vehicle 1 equipped with the low-frequency sound source 2, a plurality of underwater vehicles 1 equipped with a receiver 3 are prepared, and a plurality of underwater vehicles equipped with the receiver 3 are prepared. In a state where the traveling body 1 is arranged so as to surround the search target object 7, a low frequency is applied from the low frequency sound source 2 of the underwater vehicle 1 including the low frequency sound source 2 toward the search target object 7. The scattered wave 9 generated by the low-frequency search target object 7 is received by the receivers 3 of the plurality of underwater vehicles 1 arranged so as to surround the search target object 7. By doing so, the direction in which the level of the scattered wave is increased depending on the shape and orientation of the object to be searched 7 is found, and the scattered wave 9 is measured in the direction in which the level of the scattered wave is increased. You may do it. In this way, the scattered wave 9 of the exploration target object 7 can be detected at a high level regardless of the shape and orientation of the exploration target object 7, and the frequency pattern of the scattered wave 9 can be analyzed well. become able to.

  As the navigation body, it is preferable to use the underwater navigation body 1 from the viewpoint that it is easy to specify the position with respect to the exploration target object 7, but a marine navigation ship may be used.

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

It is a general | schematic cutting side view which shows one Embodiment of the exploration classification method and apparatus of the underwater object of this invention. It is a schematic front view which shows the state which is exploring the underwater object by what is shown in FIG. It is a schematic diagram which shows the frequency pattern of the scattered wave by a hollow elastic body.

Explanation of symbols

1 Underwater vehicle (Navigator)
2 Low frequency sound source (transmitter)
3 Receiver 5 Signal processor (analyzer)
6 Navigation system 7 Object to be searched 9 Scattered wave

Claims (5)

  From the above-mentioned transmitter in a traveling body equipped with a transmitter, a receiver, and a navigation device, a low frequency whose frequency is changed in a predetermined band is transmitted to an object under the seabed, The low-frequency scattered wave from the object is received by the receiver, and the frequency pattern of the scattered wave received by the receiver is an object whose shape, size, material, and plate thickness are known in advance. Searching for underwater objects characterized by detecting the object to be searched and classifying its shape, size, etc. by collating with a database that stores the frequency pattern of scattered waves Method.   A low frequency with a frequency changed in a predetermined band is transmitted from the transmitter in the traveling body including the transmitter and the navigation device to the underwater object, and the low frequency by the low frequency object under the water is transmitted. A scattered wave of a frequency is received by a receiver in a traveling body equipped with a receiver and a navigation device, and the frequency pattern of the scattered wave received by the receiver is previously shaped and sized. Detecting the object to be searched and classifying its shape, size, etc. by collating it with a database that stores the frequency patterns of scattered waves from objects with known materials and plate thickness Characteristic method for exploring underwater objects.   As a low frequency to be transmitted from the transmitter, a pulse wave having a slightly different frequency is transmitted so as to cover a bandwidth of 20 kilohertz or less, or a certain frequency bandwidth by frequency modulation. The method according to claim 1 or 2, wherein a low-frequency wave is used to transmit a pulse wave to be able to cover a bandwidth of 20 kilohertz or less.   A transmitter and receiver for transmitting a low frequency whose frequency is changed in a required band are mounted on a water or underwater vehicle equipped with a navigation device. The frequency pattern received by the receiver while the low frequency wave is scattered by the object under the bottom of the water is accumulated as the frequency pattern of the scattered wave from an object with a known shape, size, material, and plate thickness. An underfloor object exploration classification apparatus comprising an analysis unit configured to collate with a database to detect an object to be explored and classify the shape, size, and the like.   The underfloor object exploration classification apparatus according to claim 4, wherein the transmitter and the receiver are individually mounted on a traveling body including a navigation device.

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