JP2012108122A - Submarine audio/video system - Google Patents

Abstract

Provided is a submarine acoustic image system capable of generating a three-dimensional image of an object at the bottom of the sea, on the sea bottom, and under the sea bottom with high resolution by using a synthetic aperture technique and an interferometry technique.
A transmitter is attached to a platform for navigating in the sea and irradiates a first exploration wave to the bottom of the sea in a direction perpendicular to the direction of navigating, a direction perpendicular to the direction of navigating, and the first The received wave array 74 that receives the reflected waves and is arranged in a direction intersecting the irradiation direction of the exploration wave, the synthetic aperture calculation processing unit that generates the synthetic aperture processing information from the reflected waves, and the position information of the platform 60 The arrival angle of the reflected wave is calculated based on the inertial navigation device to be generated and the phase difference between the reflected waves subjected to the synthetic aperture processing, and the reflection source of the reflected wave is calculated based on the angle of arrival and the position information. An interferometry calculation unit that calculates a three-dimensional position.
[Selection] Figure 1

Description

  The present invention relates to a submarine audio video system using a synthetic aperture technique, and more particularly to a submarine audio video system capable of detecting the position and shape of an object buried under the seabed.

  Prior to the construction of the facility on the ocean floor or the ocean floor, exploration / recovery of harmful hazardous materials such as bombs and mines is carried out on the ocean floor and below the ocean floor. As a conventional technique for detecting an object on the seabed and an object buried under the seabed, there is a magnetic exploration technique. In the magnetic exploration technique, for example, a local magnetic field is detected based on a magnetic difference detected by two magnetic coils that are arranged at a constant interval and differentially connected, and an object that generates the local magnetic field is searched. However, magnetic exploration is a technology that confirms the presence or absence of an object based on the strength of the reaction, but it includes a position error of several meters, and it is difficult to distinguish whether it is exposed on the seabed or buried under the seabed. It is difficult to specify the size and shape. Therefore, even if a magnetic anomaly was detected, the probability that a hazardous hazardous substance was actually found there was extremely low.

  Therefore, a synthetic aperture sonar technique based on underwater acoustics has attracted attention as a technique for recognizing the shape of an object at the bottom of the seabed and under the seafloor. Synthetic aperture sonar technology uses a plurality of data that is acquired from time to time in a transmitting / receiving device mounted on a moving body that travels in the sea to reconstruct data (formation of a hologram image) at a certain location. This is a technique for improving the resolution of an image. In order to obtain data on the ocean floor and below the ocean floor, it is necessary to irradiate the ocean with sound waves and receive the reflected waves. To obtain data below the ocean floor, the sound waves are transmitted below the ocean floor. Therefore, it is necessary to irradiate a sound wave having a low frequency of several tens of KHz or lower. Furthermore, various techniques are required to recognize the shape of an object with high resolution. For example, in Patent Document 1, the time difference between the sound wave propagation time of the seabed sedimentary layer and the sound wave propagation time when there is no sedimentary layer is given as resampling of the sonar received signal or correction of the curvature shape in the synthetic aperture processing. Further, a technique for improving the position accuracy and the resolution of drawing using the brightness and contrast of an object in an image after synthetic aperture processing due to the presence of a seabed sedimentary layer as a focus evaluation index is disclosed.

JP 2010-175429 A

  Here, in the prior art including Patent Document 1, a sonar and an inertial navigation device are attached to a moving body that navigates in the sea, and a synthetic aperture image is obtained from position information obtained by the inertial navigation device and reflected wave information obtained by the sonar. I was getting. However, the position information obtained by the inertial navigation device increases in error over time, so it is difficult to obtain a synthetic aperture image with high resolution. Therefore, when the detected sound wave is reflected under the sea bottom, it is difficult to specify the shape of the object that reflects the sound wave and to calculate the position and depth.

  Accordingly, the present invention pays attention to the above-mentioned problems, and uses synthetic aperture technology and interferometry technology to obtain a high-resolution 3D image of an object on the seabed and the seabed and an object below the seabed at a high resolution. An object of the present invention is to provide a submarine audiovisual system that can be generated.

  In order to achieve the above object, a submarine audiovisual system according to the present invention is first attached to a platform navigating in the sea, and a first exploration wave is applied to the bottom surface in a direction perpendicular to the direction in which the platform navigates. A transmitter to be irradiated; and a transmitter mounted on the platform, arranged in a direction perpendicular to a direction in which the platform navigates, and in a direction intersecting with the irradiation direction of the first exploration wave, and reflecting the reflected wave of the first exploration wave A plurality of receivers each receiving a wave, a synthetic aperture calculation processing unit that generates synthetic aperture processing information from the reflected wave of the first exploration wave, and inertial navigation that is attached to the platform and generates position information of the platform And the first exploration wave based on the phase difference between the reflected waves of the synthetic exploration processed first exploration wave constituting the synthetic aperture processing information. An interferometry calculating unit that calculates an arrival angle of a wave and calculates a three-dimensional position of a reflection source of the reflected wave of the first exploration wave based on the arrival angle and the position information; It is characterized by having.

  With the above configuration, the three-dimensional position of the reflection source of the reflected wave can be calculated by using the synthetic aperture technique and the interferometry technique together. Reflected waves are reflected not only on objects on the sea floor but also above the sea floor. Therefore, by calculating this corresponding to all position information, an ocean bottom acoustic image that can generate a three-dimensional image above the object and the object placed on the sea bottom, which is the reflection source of the reflected wave. System.

  Second, the first exploration wave has a wavelength band that can be transmitted below the sea floor, and the synthetic aperture processing information includes information on the sea bottom reflected wave reflected on the sea bottom, Information on the submarine reflected wave reflected at the seafloor, and the interferometry computing unit includes the submarine reflected wave and the submarine reflected wave having the same angle of arrival as the submarine reflected wave. Based on the time difference of the arrival time of the receiver to the receiver, the information on the bottom reflected wave and the information on the submarine reflected wave are respectively extracted from the synthetic aperture processing information and the information on the time difference is extracted. Generating and calculating the reflection position of the bottom reflected wave having the same angle of arrival as the reflected wave from the bottom of the sea, thereby calculating information on the passing position of the reflected wave from the bottom of the sea on the bottom of the sea; And the passing position information and the time difference information. There are characterized by a can be calculated three-dimensional position of the reflection source of the seabed reflected wave.

  With the above configuration, it is possible to calculate the position and depth of the reflection source of the submarine reflected wave by using the synthetic aperture technique and the interferometry technique in combination. Then, by calculating this corresponding to all position information, a three-dimensional image representing the shape, position, and depth of the object buried under the sea floor, which is the reflection source of the submarine reflected wave, is generated. It becomes a submarine audiovisual system that can do this.

  Third, irradiate a second exploration wave attached to the platform and reflected from the sea floor in a direction perpendicular to the direction of navigation of the platform and a direction intersecting the irradiation direction of the first exploration wave, A high-frequency transmitter / receiver that receives a reflected wave of the second exploration wave, and the interferometry calculating unit uses the high-frequency sea bottom information generated from the reflected wave of the second exploration wave The information on the reflected wave under the seabed is extracted from the information.

  With the above configuration, when it is difficult to extract the information on the reflected sea bottom wave and the information on the sea floor reflected wave from the synthetic aperture processing information, the high frequency based on the reflected wave of the second exploration wave that does not pass below the sea floor. By using the sea bottom information, it is possible to identify the information on the reflected submarine reflected wave from the synthetic aperture processing information.

Fourthly, three or more receivers are arranged in a direction perpendicular to a direction in which the platform navigates and in a direction intersecting with the irradiation direction of the first exploration wave.
With the above configuration, it is possible to increase the resolution of the arrival angle of the reflected wave of the first exploration wave detected by the receiver, and to suppress noise in the synthetic aperture processing information.

  Fifth, the sound signal for positioning (question signal) is transmitted to the platform while being placed on the sea, and the reflected signal (response signal for the question signal) of the sound signal for positioning reflected from the platform is received. Positioning means for calculating information on the relative position with respect to the platform, and the positioning means generates positioning information on the platform based on the information on the relative position and geographic information of the positioning means based on GPS positioning. And output to the inertial navigation device, and the inertial navigation device updates the position information with the positioning information.

  With the above configuration, the inertial navigation apparatus can update the position information with the positioning information generated with the accuracy of the geographical information based on the information on the relative position and the GPS positioning. Therefore, in synthetic aperture processing information and 3D images, resolution degradation due to errors in the position information of the inertial navigation system is suppressed, and 3D images of objects on the seabed and the seabed and objects below the seabed are displayed. Can be generated with high resolution.

Sixthly, the positioning means receives a reflected signal (reply signal) of the positioning acoustic signal (question signal) and receives a wave receiving means for detecting a phase difference in three directions orthogonal to each other of the reflected signal. And generating the relative position information based on the phase difference.
Thereby, even in a narrow sea area, a submarine audio video system capable of calculating the relative position between the positioning means and the platform without using a large-scale device is obtained.

Seventh, the sound signals for positioning are transmitted to the platform while being arranged at sea, and the return times of the reflected signals (reply signals) of the sound signals for positioning (question signals) reflected from the platform are respectively set. A plurality of positioning means for calculating, wherein any one of the plurality of positioning means includes information on the return time calculated by each positioning means and at least one of the positioning means among the plurality of positioning means; And generating the positioning information of the platform based on the geographical information based on the GPS positioning and outputting the positioning information to the inertial navigation device, and the inertial navigation device updates the position information with the positioning information. .
Thereby, it becomes a submarine audio visual system which can calculate the position information of a platform.

Eighth, a transponder is disposed on the platform, and the transponder receives the positioning acoustic signal as a question signal and transmits a return signal as a reflection signal of the positioning acoustic signal.
With the above-described configuration, the reflected signal of the positioning acoustic signal can be transmitted with high intensity, and the platform positioning information using the positioning means can be easily generated.

Ninth, the positioning means includes an actuator for moving the positioning means, and the output of the actuator can be adjusted so that the relative position between the platform and the positioning means is constant. To do.
Thereby, it becomes a submarine audio visual system which can suppress the fluctuation | variation of the relative position of a platform and a positioning means, and can suppress the error of the information of a relative position.

Tenth, a plurality of positioning means for transmitting a positioning acoustic signal to the platform and calculating a return time of the reflected signal of the positioning acoustic signal reflected from the platform are fixed to the seabed. Generating the platform positioning information based on the return time information calculated by the means and the position information of each positioning means, and outputting the positioning information to the inertial navigation device. The inertial navigation device uses the positioning information. The position information is updated.
Thereby, since the position of the positioning means can be known, it becomes a submarine acoustic image system capable of generating the positioning information of the platform outside without using the geographical information based on the GPS positioning.

  According to the submarine acoustic video system according to the present invention, since the position information obtained by the inertial navigation device is updated with geographical information based on GPS positioning, deterioration in resolution of the synthetic aperture processing information (synthetic aperture image) and the three-dimensional image is suppressed. It is possible to identify not only an object on the sea floor but also an object buried under the sea floor, and it is possible to specify the shape and calculate the position and depth.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the submarine audio visual system of this embodiment, FIG. 1 (a) is an outline (front view) of the submarine audio visual system of 1st Embodiment, FIG.1 (b) is a bottom view of a surface tracking buoy and a platform. FIG. 1 (c) is a partial detail view of the submarine audiovisual system. The irradiation range of the 1st exploration wave irradiated from a transmitter and the irradiation range of the 2nd exploration wave irradiated from a high frequency transducer are shown. It is a figure which shows the principle of interferometry. It is a figure which shows the propagation path of the 1st exploration wave when the object used as a reflection source is buried under the sea bottom. It is the figure which compared the information of the reflected wave of the 1st exploration wave, and the information of the reflected wave of the 2nd exploration wave. It is a block diagram which becomes an example of the submarine acoustic image system of this embodiment. It is a block diagram which becomes an example of the image generation process of this embodiment.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  FIG. 1 shows an outline of the submarine audiovisual system of the present embodiment, FIG. 1A is an outline (front view) of the submarine audiovisual system of the present embodiment, and FIG. 1B is a bottom surface of the surface tracking buoy and the platform. FIG. 1 and FIG. 1C are partial detailed views of the submarine audiovisual system. FIG. 2 shows the irradiation range of the first exploration wave irradiated from the transmitter and the irradiation range of the second exploration wave irradiated from the high frequency transducer.

  The undersea acoustic imaging system 10 of the present embodiment includes an observation ship 12, a surface tracking buoy 28 that is arranged in a floating state and can be moved by an actuator, and a platform 60 that navigates in the sea. Have. The observation ship 12 is provided with a wireless LAN terminal 14 (PC, monitor). The surface tracking buoy 28 includes a wireless LAN terminal 30, an acoustic modem 46, and the like. The platform 60 is also provided with an acoustic modem 62.

  Therefore, the wireless LAN terminal 14 provided on the observation ship 12 and the wireless LAN terminal 30 provided on the surface tracking buoy 28 can communicate with each other via the wireless LAN 16. In addition, the acoustic modem 46 provided on the surface tracking buoy 28 and the acoustic modem 62 provided on the platform 60 are capable of bidirectional communication using a communication signal 58 (sound wave). The communication signal 58, the question signal 108 (positioning acoustic signal) described later, the reply signal 108a (reflection wave of the positioning acoustic signal) described later, the first search wave 92 and the second search wave 93 described later are It shall have a frequency that does not interfere.

  The wireless LAN terminal 14 installed on the observation ship 12 includes a PC (personal computer), a monitor (not shown), a mouse (not shown), a keyboard (not shown), and the like. Further, the wireless LAN terminal 14 is connected to a handle (not shown) that controls the platform 60 through an interface (not shown). The wireless LAN terminal 14 can give various instructions to the surface tracking buoy 28 and the platform 60 via the wireless LAN 16. The observation ship 12 stands by at a position sufficiently away from the surface tracking buoy 28 and the platform 60 so as not to cause the noise of the reflected wave 92a and the reflected wave 93a described later, such as the engine sound of the observation ship 12.

  The surface layer tracking buoy 28 calculates the positioning information 54 of the platform 60 and transmits it to the platform 60 side. The surface tracking buoy 28 moves so as to maintain a certain distance from the platform 60. Therefore, a transducer 32, a thruster 44, and a GPS receiver 40 are installed on the surface tracking buoy 28.

  The surface tracking buoy 28 is attached with an interrogation signal transmitter 64 that transmits an interrogation signal 108, and transmits the interrogation signal 108 toward the transponder 61 arranged on the platform 60.

  The transducer 32 serving as positioning means is used to calculate the relative position between the surface tracking buoy 28 and the platform 60 by the SSBL (Super Short Base Line) method. The transducers 32 are arranged at different positions in three directions orthogonal to each other, for example, the X-axis direction (azimuth direction), the Y-axis direction (ground range direction), and the Z-axis direction (vertical direction), and transmitted from the transponder 61. It is composed of a plurality of receiving elements (not shown) that receive the reply signal 108a. Then, a phase difference in the X-axis direction, Y-axis direction, and Z-axis direction of the received reply signal 108a is calculated by a wave receiving element (not shown), and the surface layer tracking buoy 28 and the platform 60 are calculated based on this phase difference. The relative position can be calculated. By using the SSBL acoustic positioning system in this manner, the relative position between the surface tracking buoy 28 and the platform 60 can be calculated without using a large-scale device even in a narrow sea area.

  The thruster 44 serving as an actuator moves the surface tracking buoy 28 on the sea surface. The thruster 44 moves and rotates the surface tracking buoy 28 by adjusting the corresponding output parameter 56 (see FIG. 6) as described later.

  As a result, the surface tracking buoy 28 moves in the X-axis direction (azimuth direction), the Y-axis direction (ground range direction) perpendicular to the X-axis, and the Z-axis (vertical direction) perpendicular to the X-axis and Y-axis. Rotational motion can be performed about the rotation axis.

  The platform 60 basically proceeds in the sea in a constant direction at a constant speed. A thruster 112 is attached to the platform 60. A surge (front-rear) in the X-axis direction (azimuth direction), a sway (left-right) in the Y-axis direction (ground range direction), and a Z-axis direction (vertical direction) with respect to the platform 60. Heave (up and down) translation can be performed. Among these, the direction of navigation when the platform 60 irradiates a first exploration wave 92 and a second exploration wave 93 described later is an azimuth direction.

  Further, the thruster 112 can cause the platform 60 to perform roll (X-axis rotation), pitch (Y-axis rotation), and yaw (Z-axis rotation) rotational movements. The movement of the platform 60 can be performed by controlling the output of the thruster 112 based on the navigation program information input in advance or the signal input from the wireless LAN terminal 14 of the observation ship 12 or the like.

  Further, a transponder 61, an inertial navigation device 68 (see FIG. 7), and a Doppler velocimeter 70 are attached to the platform 60. When the transponder 61 receives the interrogation signal 108 transmitted from the interrogation signal transmitter 64, the transponder 61 transmits a reply signal 108a. By disposing the transponder 61, the reply signal 108a (reflection signal of the positioning acoustic signal) can be transmitted with a large intensity, and the generation of the positioning information 54 described later of the platform 60 using the surface tracking buoy 28 is facilitated. It can be carried out.

  The inertial navigation device 68 generates acceleration information at a constant time interval, further integrates it to generate speed information and position information, and outputs them to the storage unit 84 (see FIG. 7) described later. In addition, the inertial navigation device 68 generates the posture information of the platform 60 as described later and outputs it to the storage unit 84 (see FIG. 7) described later.

  The Doppler speedometer 70 generates speed information in the X-axis direction and the Y-axis direction. The Doppler velocimeter 70 irradiates, for example, laser light from the front side and the rear side in the speed direction (X-axis direction and Y-axis direction) with respect to the same position on the sea bottom, which is the object to be measured, The component of the relative velocity between the sea floor and the platform 60 is extracted by detecting the magnitude of the wavelength change of the scattered light.

  The platform 60 may be equipped with a camera 104 (see FIG. 6) for taking a picture of the sea and the sea bottom as a still image or a moving image, and a water depth gauge 106 (see FIG. 6) for measuring the water depth by water pressure. It is also possible to output information of the camera 104 that represents a still image or moving image of the sea or the seabed, and information of the depth meter 106 that indicates the water depth.

  Furthermore, there is a case where a plate 60a is attached to the platform 60 as shown in FIG. 1, and the plate 60a has its normal line oriented perpendicularly to the azimuth direction (advancing direction of the platform 60) as shown in FIG. It is fixed so as to face a certain angle (slant range direction) (off nadir angle: φ) toward the seabed in the state.

  As shown in FIG. 1, the transmitter 72, the receiver array 74 serving as a receiver, and the high-frequency transmitter / receiver 76 have the same direction of sound wave irradiation and reception as in the normal line of the plate 60a. It is installed so as to face a certain angle (slant range direction, off-nadir angle: φ) toward the seabed in a state perpendicular to the azimuth direction (see FIG. 2). In FIG. 1 and the like, the transmitter 72, the receiving array 74, and the high-frequency transmitter / receiver 76 are attached to the plate 60a. However, as long as these components are arranged on the platform 60 in the above-described orientation, It is not always necessary to attach the components to the plate 60a. The transmitter 72 irradiates the first exploration wave 92 toward the seabed, and the receiving array 74 receives the reflected wave 92a (see FIG. 3) of the first exploration wave 92 (see FIG. 3) reflected by the seabed. To do.

  As shown in FIG. 1C, the receiving array 74 (receiver) is formed by arranging a plurality (five in the figure) of receiving elements in a line in the azimuth direction. In the present embodiment, the receiving array 74 is arranged in a direction (see FIG. 1C) perpendicular to the direction (azimuth direction) in which the platform 60 navigates and in the irradiation direction (slant range direction) of the first exploration wave 92. A plurality are arranged at intervals in the intersecting direction (see FIG. 3). Therefore, the information of the reflected wave 92a is generated for each wave receiving element, and is stored in a storage unit 84 (see FIG. 7) described later in a state where the information can be distinguished from each other.

  In the present embodiment, the resolution in the azimuth direction can be increased by performing synthetic aperture processing on the information of the reflected wave 92a. Here, when the length of the receiving element in the azimuth direction is L, the theoretical resolution in the azimuth direction of the synthetic aperture processing information (synthetic aperture image) is L / 2. The transmitter 72 can irradiate the pulsed first exploration wave 92 in the range direction with frequency modulation (for example, chirp modulation) applied. Then, the resolution in the range direction can be increased by compressing the information of the reflected wave 92a of the first exploration wave 92. Here, the synthetic aperture processing information refers to information on a reflected wave 92b (time series information such as the intensity and phase of the reflected wave 92b), which will be described later, with improved resolution by the above-described method, and position information (geographical information on the seabed). Information) and the information of the reflected wave 92b is made to correspond to all the position information included in the search range. Since synthetic aperture processing and frequency modulation are conventional techniques, explanations thereof are omitted.

  The first exploration wave 92 has a low frequency of several tens of kHz or less and a low frequency that can be transmitted under the seabed. Therefore, when an object is buried under the sea bottom, the first exploration wave 92 is reflected by the object. That is, the reflected wave 92a has a component reflected at the sea bottom and a component reflected below the sea bottom. However, since a considerable portion of the first exploration wave 92 is reflected on the sea bottom, the intensity of the component reflected on the sea bottom increases, but the intensity of the component reflected below the sea bottom decreases.

  When there is only one wave receiving array 74 as in the prior art, from the return time until the wave receiving array 74 receives the reflected wave 92a after the first exploration wave 92 is irradiated, from the object to be the reflection source Can be measured, but its direction, i.e. the position of the reflection source, cannot be measured. Therefore, in the present embodiment, as will be described later, the reflected wave 92b (the first exploration wave 92 constituting the synthetic aperture processing information is formed by the interferometry technique using the transmitter 72 and the plurality of receiving arrays 74. The angle of arrival of the reflected wave (synthetic aperture processed) is calculated.

  The high-frequency transmitter / receiver 76 receives a reflected wave from the sea bottom and generates high-frequency sea bottom information. Therefore, the high-frequency transmitter / receiver 76 directs the second exploration wave 93 (see FIG. 7) having a frequency that is hardly transmitted below the seabed and reflected by the seabed toward the seabed at a certain irradiation angle (slant range direction). ) And the reflected wave 93a (see FIG. 5) is received. As shown in FIG. 2, the high frequency transducer 76 has an irradiation angle similar to that of the transducer 72, and has a very narrow angle in the azimuth direction and a wide angle in the range direction (near range to far range). 2 The exploration wave 93 can be irradiated. Therefore, the high-frequency seabed information has resolution in the azimuth direction corresponding to the width of the second exploration wave 93 in the azimuth direction, and resolution in the range direction corresponding to time-series temporal resolution of the intensity of the reflected wave 93a.

  FIG. 3 shows the principle of interferometry. As shown in FIG. 3, the transmitter 72 and the receiving array 74 are arranged side by side in the direction perpendicular to the range direction and the azimuth direction.

  First, consider the case where there are two receiving arrays 74. When the first exploration wave 92 is irradiated from the transmitter 72, the first exploration wave 92 is reflected in a spherical wave shape at the target O serving as a reflection source, and there is a sufficient distance from the target O to the wave receiving array 74. The reflected wave 92b (92a) reaches the receiving array 74 as a substantially plane wave. However, since the distance between each receiving array 74 and the target O is different from each other, the time for the reflected wave 92b (92a) to reach each receiving array, that is, the phase of the reflected wave 92b (92a) is different. Therefore, the arrival angle (α) of the reflected wave 92b can be calculated based on the phase difference of the reflected wave 92b generated between the receiving arrays 74, and the return time of the first exploration wave 92 to the receiving array 74 can be calculated. Based on this, the three-dimensional position (plane position, depth) of the target O can be calculated.

  Further, as described above, even when the transmitter 72 and the receiving array 74 are placed on the plate 60a, they are arranged at different positions, so that the reflected wave 92b reflected from the target O is received by the receiving array 74. There is always a phase difference between the two. Therefore, if there is a signal with no phase difference, it can be removed as noise. The above calculation can be performed in an interferometry calculation unit 80 described later.

  Here, when the dimension between the receiving arrays 74 is set so narrow that the phase difference of the reflected wave 92b detected in the range in the range direction (near range to far range) does not exceed 2π, it is detected. Since the phase difference is always 2π or less, the arrival direction of the reflection source can be calculated, but the resolution is not high. On the other hand, when the dimension between the receiving arrays 74 is designed widely beyond the above-mentioned range, the resolution for calculating the arrival direction of the reflection source is high, but the detected phase difference is a circular component (2nπ). , N: integer), there are a plurality of solutions indicating the direction of the reflection source, and it is impossible to uniquely calculate the direction of the reflection source. Therefore, in the present embodiment, three receiving arrays 74 are arranged (four or more may be used).

  As shown in FIG. 3, it is assumed that the positional relationship between the transmitter 72 and the receiving array 74 (A, B, C) is known, and these are arranged in a straight line. The interval between the receiving array 74 (A) and the receiving array 74 (B) is set to be narrow so that the phase difference between the received reflected waves does not exceed 2π. On the other hand, it is assumed that the interval between the receiving array 74 (A) and the receiving array (C) is set wide so that the phase difference between the received reflected waves exceeds 2π. In the same manner as described above, the receiving array 74 (A, B, C) receives the reflected wave 92b (reflected wave 92a), which is substantially a plane wave, at different phases.

  Here, the distance between the receiving array 74 (A) and the receiving array 74 (C) is longer than that between the receiving array 74 (A) and the receiving array 74 (B). Although the resolution for calculation is high, there are a plurality of solutions for the above-described reason, and therefore it is impossible to calculate the arrival angle (α) uniquely. However, although the resolution is low between the receiving array 74 (A) and the receiving array 74 (B), the arrival angle (α) can be uniquely calculated for the above-described reason. Therefore, among the plurality of arrival angles (α) calculated from the phase difference detected between the receiving array 74 (A) and the receiving array 74 (C), the receiving array 74 (A) and the receiving wave By selecting the one closest to the arrival angle (α) calculated from the phase difference detected with respect to the array 74 (B), the arrival angle (α) can be calculated with high resolution. Based on (α) and the return time of the reflected wave 92b, the three-dimensional position (plane position, depth) of the target O can be calculated.

  Further, when four or more receiving arrays 74 are arranged in parallel, by repeating the operation of selecting the angle closest to the angle at which the resolution is one step lower than the calculated high resolution angles, A high-resolution angle of arrival can be uniquely calculated.

  In the present embodiment, synthetic aperture processing information (reflected wave 92b) is generated based on the reflected wave 92a received by the plurality of receiving arrays 74. If any of the phase differences between adjacent receiving arrays 74 is zero in the reflected wave 92b constituting each synthetic aperture processing information, it is calculated based on the phase difference between adjacent receiving arrays 74. When a plurality of solutions indicating the positions of the targets are significantly different from each other, the reflected wave 92b that is the basis for the phase difference can be removed as noise. Therefore, by using this interferometry technique, a highly accurate three-dimensional image (synthetic aperture image) with less noise can be generated. The above calculation is performed in an interferometry calculation unit 80 described later.

  As described above, the three-dimensional position of the reflection source of the reflected wave 92b can be calculated by using the synthetic aperture technique and the interferometry technique in combination. The reflected wave 92b is also reflected by an object above the sea bottom, but is reflected most strongly at the sea bottom. Therefore, by calculating this corresponding to all the position information, it is possible to generate a three-dimensional image of the object and the sea bottom disposed above the sea bottom as a reflection source of the reflected wave 92b.

  By the way, when there is an object to be a reflection source buried under the sea bottom, the reflected wave 92b is also reflected from under the sea bottom. The reflected wave 92b of the first exploration wave 92 has the largest component reflected from the sea bottom (the sea bottom reflected wave 92d: FIG. 4), and is the component reflected below the sea bottom. What has arrived at the same angle of arrival as 92d (submarine reflected wave 92c: FIG. 4) arrives at the receiving array 74 in time after the seafloor reflected wave 92d. Therefore, the reflected wave 92b has a sea bottom reflected wave 92d and a submarine reflected wave 92c, but they can be distinguished from each other. However, since the sound wave is refracted at the sea bottom, the above-described method cannot calculate the original position and depth of the submarine reflected wave 92c. Therefore, in the present embodiment, from the information of the reflected wave 92b, the information of the sea bottom reflected wave 92d reflected on the sea bottom and the information of the submarine reflected wave 92c (sub-bottom reflected wave) reflected under the sea bottom. Are extracted, and the position of the reflection source of the reflected wave reflected under the sea floor is calculated.

  FIG. 4 shows a propagation path of a sound wave when an object as a reflection source is buried under the sea bottom. FIG. 5 shows a comparison between information on the reflected wave of the first exploration wave and information on the reflected wave of the second exploration wave. As described above, the arrival angle α and the return time of the reflected wave 92b (the sea bottom reflected wave 92d, the submarine reflected wave 92c) are calculated by the interferometry technique. On the other hand, the inclination β (inclination of the plate 60 a) of the transmitter 72 and the receiving array 74 is known when attached to the platform 60, and the change amount of β is also obtained from the attitude information calculated by the inertial navigation device 68. The angle θ formed between the traveling direction of the reflected wave 92b and the sea bottom can be calculated.

  However, since the submarine reflected wave 92c is refracted at the bottom of the sea, the actual target O is positioned as shown in FIG. 4, and the interferometry calculation does not take into account the refraction at the bottom of the sea. The arrival angle α and the return time are calculated for the reflected submarine wave 92c reflected from the target O ′.

  On the other hand, since the 1st exploration wave 92 is irradiated in the range direction (near range-far range), the sea bottom reflection which uses the sea bottom (for example, the position of A, B, C, D, E) in the range as a reflection source. A wave 92d is generated.

  Further, the sea bottom reflected wave 92d includes a wave that reaches the receiving array 74 at the same angle θ as the submarine reflected wave 92c reflected from the sea bottom and reflected below the sea bottom (A in FIG. 4). That is, in FIG. 4, the passage position of the submarine reflected wave 92c on the bottom surface coincides with the reflection position of the bottom surface reflected wave 92d that has reached the receiving array 74 at the same arrival angle α. Further, the position of the receiving array 74 (platform 60) is calculated by the inertial navigation device 68.

  Therefore, it is possible to calculate A reflected by the sea bottom reflected wave 92d using information on the sea bottom reflected wave 92d, and information on the passage position (refractive position) of the sea bottom reflected wave 92c that coincides with A on the sea bottom. Can be calculated. Furthermore, the position of the target O can be calculated by using the sound velocity v1 in water and the sound velocity v2 in the soil that forms the bottom of the seabed.

  As shown in FIG. 4, the distance R from the receiving array 74 to the position A can be obtained by the product of the propagation velocity v1 of the sound wave and the return time t1 from A to the receiving array 74. Here, v1 is known by measuring the speed of sound in the sea, and t1 is calculated from the arrival time of the receiving array 74 of the information of the bottom reflected wave 92d having the same angle of arrival as the reflected wave 92c below the seabed in FIG. Can do. Therefore, the position of A on the sea bottom can be calculated from the position of the receiving array 74 (platform 60) known by the inertial navigation device 68 and θ, v1, and t1.

  Also, the time t2 when the submarine reflected wave 92c reaches from the target O to A is, as shown in FIG. 5, a receiving array 74 of information on the submarine reflected wave 92c and information on the submarine reflected wave 92d in A. It can be obtained by taking the time difference of the arrival times. Therefore, the distance r from the target O to A can be calculated by the product of the sound velocity v2 in the soil that forms the bottom of the seabed and t2. This v2 becomes known by actual measurement.

  In addition, the angle θ ′ formed by the reflected submarine reflected wave 92c with respect to the sea bottom can be calculated by using Snell's law and the like because θ, v1, and v2 are known.

  Therefore, the position of the target O can be calculated using the position of A that has become known, r, θ ′, and the depth of the target O from the sea bottom can also be calculated using r, θ ′. it can. Then, by calculating this corresponding to all the position information, it is possible to calculate the image of the object buried under the sea bottom, which is the reflection source of the submarine reflected wave 92c, and its position and depth. The above calculation can be performed in the interferometry calculation unit 80.

  By the way, when the undulations of the sea bottom to be surveyed are severe, or due to the quality of the soil on the sea bottom, the intensity of the reflected wave 92a (92b) of the first exploration wave 92 on the sea bottom decreases, and the sea bottom reflected on the sea bottom is reflected. It may be difficult to specify the reflected wave 92d. That is, from the reflected wave 92b of the first exploration wave 92 received by the receiving array 74, information on the sea bottom reflected wave 92d in A, B, C, D, E and the target O shown in FIGS. In some cases, it is difficult to identify and extract the information of the reflected submarine reflected wave 92c from the ocean.

  Therefore, in the present embodiment, the high-frequency transducer 76 irradiates the seabed with the second exploration wave 93 in the same manner as the first exploration wave 92, and generates high-frequency seabed information as in the synthetic aperture processing information. Here, the high-frequency seabed information is generated by generating time-series information of the intensity of the reflected wave 93a corresponding to the position information (geographic information of the seabed) of the platform 60, and includes all the position information included in the search range. The information of the reflected wave 93a is made to correspond.

  As described above, the second exploration wave 93 does not transmit below the sea bottom and is reflected by the sea bottom, but the reflection characteristics at the sea bottom are the same regardless of the frequency of the sound wave. Therefore, the component reflected by the sea bottom reflected wave 92d in the synthetic aperture processing information has sea bottom information similar to the high frequency sea bottom information by the reflected wave 93a of the second exploration wave 93. Therefore, if A, B, C, D, and E in FIG. 4 are the reflection sources of the sea bottom reflected wave 92d, they are also the reflection sources of the reflected wave 93a of the second exploration wave 93. Therefore, the information on the reflected sea wave 92d shown in FIG. 5 is identified after the information on the reflected sea wave 92d is specified by associating the information on the reflected wave 93a constituting the high frequency sea floor information with the information on the reflected wave 92b. By taking the difference between the reflected wave information 93a and the reflected wave 93a of the second exploration wave 93, it is possible to extract the information of the reflected submarine reflected wave 92c reflected under the sea floor. Then, using the information on the bottom reflected wave 92d whose arrival angle matches the information on the reflected submarine reflected wave 92c, the position of the reflection source of the reflected submarine reflected wave 92c and the depth from the bottom can be calculated in the same manner as described above. .

  FIG. 6 shows a block diagram as an example of the submarine acoustic image system of the present embodiment. The wireless LAN terminal 14 (PC, monitor) provided in the observation ship 12 outputs a signal for driving the above-described thruster 112 with a constant output via the wireless LAN 16 and the communication signal 58, and the platform 60 is arbitrarily advanced. Direction and rotational direction. Note that during the search, the output of each thruster 112 is adjusted so that the platform 60 can travel at a constant speed in the azimuth direction. Information on the camera 104 attached to the platform 60 and information on the value of the depth gauge 106 are received via the communication signal 58 and the wireless LAN 16 and displayed on the wireless LAN terminal 14 (monitor). It is assumed that the operator can observe after the exploration. The wireless LAN terminal 14 can output a search start signal and a search end signal to the platform 60 side.

  In addition, the wireless LAN terminal 14 includes a synthetic aperture processing calculation unit 78, and uses the information on the reflected wave 92 a of the first exploration wave 92 stored in the storage unit 84, which will be described later, the positional information, and the posture information. Generate processing information. Further, the wireless LAN terminal 14 includes an interferometry calculation unit 80, and information on the reflected wave 93a of the second exploration wave 93 stored in the storage unit 84, position information, posture information, and synthetic aperture processing information (reflection) A wave 92b) is used to generate a three-dimensional image of the reflection source on or below the seabed.

  The wireless LAN terminal 30 of the surface tracking buoy 28 outputs these signals to the acoustic modem 46 when various signals are input from the observation ship 12 side. Further, when various information is input from the acoustic modem 46, the wireless LAN terminal 30 outputs them to the wireless LAN terminal 14 of the observation ship 12.

  When an exploration start signal is input from the wireless LAN terminal 14, the control unit 31 sends a trigger signal as an inquiry signal at a fixed period (for example, a frequency signal obtained by dividing the oscillation signal of a crystal oscillator by a frequency divider). Output to the transmitter 64, the oscillating measurement device 33, the return time calculation unit 35, and the GPS receiver 40, respectively, and when the search stop signal is input, the output of the trigger signal is stopped. When the trigger signal is periodically input from the control unit 31, the interrogation signal transmitter 64 periodically transmits the interrogation signal 108.

  Upon receiving the reply signal 108 a transmitted from the transponder 61, the transducer 32 outputs phase difference information 48 to the relative position information calculation unit 36 and outputs a trigger signal to the return time calculation unit 35. The return time calculation unit 35 calculates the return time from when the query signal 108 is transmitted until the return signal 108a is received from the time difference between the trigger signal from the control unit 31 and the trigger signal from the transducer 32, and the return time is calculated. Information is output to the relative position information calculation unit 36.

  The relative position information calculation unit 36 includes return time information input from the return time calculation unit 35, phase difference information 48 input from the transducer 32, and pre-input information on the propagation speed of sound waves in the sea. , The relative position information 50 between the surface tracking buoy 28 and the platform 60 is calculated, and the relative position information 50 is output to the positioning information calculation unit 38 and the drive control unit 42.

  The fluctuation measuring device 33 is, for example, a member (member) capable of maintaining horizontal with respect to rotation about the rotation axis in the azimuth direction (X-axis direction) and rotation about the slant range direction (Y-axis direction). It has a gimbal structure (not shown) and a compass (not shown) that detects rotation about the vertical direction (Z-axis direction) as a rotation axis. Here, the gimbal structure (not shown) is, for example, the surface tracking buoy 28 based on the relative position between the surface tracking buoy 28 and the above-described member (not shown) when the surface tracking buoy 28 is horizontal. The tilt (rotation) in the X-axis direction and the Y-axis direction can be calculated as a change in the relative position. The fluctuation measuring device 33 rotates the surface tracking buoy 28 around the X axis (roll), the Y axis (pitch), and the Z axis (yaw) from the gimbal structure (not shown) and the compass (not shown). While generating posture information indicating the position, the posture information is constantly updated. Furthermore, when the trigger signal is input from the control unit 31, the motion measurement device 33 outputs the latest posture information 49 to the positioning information calculation unit 38.

  The GPS receiver 40 updates the geographic information 52 based on GPS positioning at a constant cycle by receiving radio waves from GPS satellites, but receives the trigger signal from the control unit 31 to update the latest geographic information 52. Is output to the positioning information calculation unit 38.

  The positioning information calculation unit 38 generates positioning information 54 by associating the relative position information 50 with the geographical information 52 and the posture information 49. That is, the coordinate information of the relative position information 50 is converted based on the geographic coordinates of the geographic information 52, and the position of the platform 60 is determined by correcting the error of the geographic information 52 due to the inclination (rotation) of the surface tracking buoy 28 by the attitude information 49. Information 54 is generated and output to the acoustic modem 46.

  The drive control unit 42, based on the difference between the preset relative position information of the surface tracking buoy 28 and the platform 60 input in advance and the relative position information 50 input from the relative position information calculation unit 36, The output parameter 56 is output to each thruster 44 so that the surface tracking buoy 28 faces a fixed direction with respect to the platform 60 so that the actual relative position between the platform 28 and the platform 60 becomes the set relative position.

  Thereby, the surface tracking buoy 28 can move on the sea while correcting the direction so as to keep the above-mentioned set relative position and direction as the platform 60 moves. Therefore, the surface layer tracking buoy 28 can be rotated and moved so as to maintain a certain direction and distance from the platform 60 to track the platform 60.

  The acoustic modem 46 outputs signals and information input from the wireless LAN terminal 30 and the positioning information calculation unit 38 to the acoustic modem 62 of the platform 60 via the communication signal 58. The acoustic modem 46 outputs the signal and information input from the acoustic modem 62 of the platform 60 to the wireless LAN terminal 30.

  The acoustic modem 62 attached to the platform 60 outputs signals and information input from the acoustic modem 46 to the image generation unit 66 and the thruster 112, and outputs signals and signals output from the image generation unit 66, the camera 104, and the water depth gauge 106. Information is output to the acoustic modem 46.

  FIG. 7 shows a block diagram as an example of image generation processing. The image generation unit 66 includes a control unit 67, an inertial navigation device 68, a Doppler velocimeter 70, a transmitter 72, a reception array 74, a high frequency transmitter / receiver 76, and a storage unit 84.

  The control unit 67 activates the inertial navigation device 68, the Doppler velocimeter 70, the transmitter 72, the receiving array 74, and the high-frequency transmitter / receiver 76 when receiving the search start signal, and receives the search end signal. Stop. The control unit 67 transmits a trigger signal synchronized with the control unit 31 in time after receiving the search start signal and before receiving the search end signal, to the transmitter 72, the receiving array 74, The signal is periodically transmitted to the high frequency transducer 76. Further, when the positioning information 54 is input, the control unit 67 outputs the positioning information 54 to the inertial navigation device 68.

The Doppler speedometer 70 generates speed information of the platform 60 at a constant update time, and outputs the speed information to the inertial navigation device 68.
The inertial navigation device 68 detects acceleration in the translation direction (X axis, Y axis, Z axis) of the platform 60 at regular update times, and generates velocity information and position information. The inertial navigation device 68 holds the latest acceleration information, velocity information, and position information and outputs them to the storage unit 84.

In the inertial navigation device 68, since the speed information and the position information are generated by integration, the error due to the integration constant increases with time.
Therefore, in the inertial navigation device 68, speed information is input from the Doppler speedometer 70, and positioning information 54 is input from the control unit 67, and the speed information and position information of the inertial navigation device 68 are updated.

  Further, the inertial navigation device 68 has a gimbal structure (not shown) and a compass (not shown), like the motion measurement device 33. Then, posture information indicating the rotational positions of the platform 60 around the X axis (roll), the Y axis (pitch), and the Z axis (yaw) is generated from these components, and the posture information is set at regular update times. Is updated and stored in the storage unit 84.

  As a result, the speed information and the position information output from the inertial navigation device 68 to the storage unit 84 are suppressed within a certain range corresponding to the respective update time intervals. High-resolution synthetic aperture processing information (synthetic aperture image) can be generated, and the interferometry calculation unit 80 (to be described later) can accurately calculate the three-dimensional position of the reflection source based on position information and posture information. .

  The transmitter 72 irradiates the first exploration wave 92 toward the seabed at regular time intervals according to the trigger signal input from the control unit 67 and outputs information on the irradiation time to the storage unit 84.

  When receiving the trigger signal input from the control unit 67, the receiving array 74 generates information on the reflected wave 92a of the first exploration wave 92 (time-series information such as the intensity and phase of the reflected wave 92a) and stores it. 84. At this time, the information of the reflected wave 92a includes information on the time when the trigger signal is input (time point information on the zero point). Therefore, the period of the trigger signal is a period until the receiving array 74 completely receives the reflected wave 92a (a reflected wave 93a described later) in the time direction, that is, the intensity of the reflected wave 92a detected by the receiving array 74 is zero. It is necessary to set longer than the period until. The information of the reflected wave 92 a is stored in the storage unit 84 in synchronization with the acceleration information, velocity information, position information, and posture information of the inertial navigation device 68.

  The high frequency transmitter / receiver 76 irradiates the second exploration wave 93 toward the seabed at regular time intervals according to the trigger signal input from the control unit 67. Then, the high frequency transmitter / receiver 76 receives the reflected wave 93a of the second exploration wave 93, generates information of the reflected wave 93a having time series information such as the time information when the trigger signal is received and the intensity of the reflected wave. The data is output to the storage unit 84. The information of the reflected wave 93a is stored in the storage unit 84 in time synchronization with the acceleration information, speed information, position information, and posture information of the inertial navigation device 68. Note that high-frequency seabed information can be generated by associating information on the reflected wave 93a with position information and posture information.

  The information on the reflected wave 92a, the information on the reflected wave 93a, the acceleration information, the speed information, the position information, and the posture information obtained in this manner are taken out from the storage unit 84 after the platform 60 is lifted to the sea. The data is input to a storage area (not shown) of the LAN terminal 14.

  The synthetic aperture calculation processing unit 78 generates synthetic aperture processing information using the information of the reflected wave 92a, position information, posture information, and the like, and records it in a storage area (not shown) of the wireless LAN terminal 14. This synthetic aperture processing information is composed of a reflected wave 92b of the first exploration wave 92 with enhanced resolution in the azimuth direction and the range direction. When generating the synthetic aperture processing information, the synthetic aperture calculation processing unit 78 increases the resolution in the above-described range direction based on the information of the reflected wave 92a of the first exploration wave 92 that has been frequency-modulated. it can.

  By the way, the synthetic aperture calculation processing unit 78 generates acceleration information, velocity information, position information, and posture information corresponding to the time resolution of the signal of the reflected wave 92a appearing in the information of the reflected wave 92a to generate highly accurate synthetic aperture processing information. Must be generated. Therefore, the synthetic aperture calculation processing unit 78 approximates the acceleration information, speed information, position information, and posture information generated with the time resolution related to the update time of the inertial navigation device 68 by an approximate curve such as a polynomial, and the inertial navigation device. It is possible to extract (interpolate) acceleration information, speed information, position information, and posture information with a time interval shorter than 68 update times from the approximate curve. That is, the synthetic aperture processing can be performed by generating acceleration information, velocity information, position information, and posture information corresponding to the time resolution of the signal of the reflected wave 92a. Thereby, the distortion of the synthetic aperture image generated from the synthetic aperture processing information can be suppressed and the resolution can be improved.

  The interferometry calculating unit 80 calculates the arrival angle (see FIG. 4) of the reflected wave 92b from the phase difference of the information of the reflected wave 92b included in the plurality of synthetic aperture processing information, and determines the reflection source of the reflected wave 92b. Calculate the three-dimensional position. Here, although the first exploration wave 92 is irradiated periodically, the phase difference between the reflected waves 92a (reflected waves 92b) of the first exploration wave 92 irradiated at one time is calculated. By performing this processing on the entire synthetic aperture processing information, information on a three-dimensional image that is a three-dimensional image obtained by adding an image of an object that is a reflection source of the reflected wave 92b and depth information (information in the Z-axis direction) is generated. And stored in a storage area (not shown) of the wireless LAN terminal 14.

  Further, the interferometry calculation unit 80 extracts the information of the sea bottom reflected wave 92d and the information of the submarine reflected wave 92c from the synthetic aperture processing information, and the three-dimensional reflection source of the submarine reflected wave 92c by the above-described method. The position of is calculated. Then, by performing this on the entire synthetic aperture processing information, the image of the object that is the reflection source of the submarine reflected wave 92c and the depth information (information in the Z-axis direction) are added to the three-dimensional image. Information is generated and stored in a storage area (not shown) of the wireless LAN terminal 14. Here, when the interferometry calculating unit 80 determines that it is difficult to extract the information of the sea bottom reflected wave 92d from the synthetic aperture processing information, it uses the information of the reflected wave 93a, the position information, and the attitude information. High-frequency sea bottom information is generated, and the information of the sea bottom reflected wave 92d is extracted from the synthetic aperture processing information in correspondence with the synthetic aperture processing information.

  Here, the interferometry calculation unit 80 is substantially the same time as the reflected wave 92b (the reflected wave 92b of the first exploration wave 92 irradiated at one time) constituting one synthetic aperture processing information. When the phase difference between the reflected wave 92b (the reflected wave 92b of the first exploration wave 92 irradiated at one time) and the reflected wave 92b that constitutes other synthetic aperture processing information is zero, The signal of the reflected wave 92b that becomes the basis of the phase difference can be removed as noise. Similarly, even if one of the phase differences is extremely different from the other phase differences, or even when the positions of the reflection sources calculated based on each phase difference are significantly different from each other, the signal of the reflected wave 92b is similarly obtained. Can be removed as noise.

  An example of the operation of the submarine audiovisual system 10 of the first embodiment will be described based on the above configuration. First, the surface tracking buoy 28 is installed in a state of floating on the sea, and the platform 60 is introduced into the sea. Then, the operator searches for the platform 60 while operating the handle (not shown) attached to the wireless LAN terminal 14 based on the underwater / underwater image and water depth information displayed on the monitor (not shown). In the range (measurement target area), the first exploration wave 92 and the like are first guided to the irradiation position.

  Then, the platform 60 is run in a predetermined direction, and the search is started by transmitting a search start signal from the wireless LAN terminal 14. The transmitter 72 installed on the platform 60 irradiates the first exploration wave 92 periodically (successively) toward the seabed, receives the reflected wave 92a by the receiving array 74, and receives information on the reflected wave 92a. Is stored in the storage unit 84. The high frequency transducer 76 installed on the platform 60 irradiates the second exploration wave 93 toward the seabed, receives the reflected wave 93a, and stores the information of the reflected wave 93a in the storage unit 84.

  On the other hand, the surface layer tracking buoy 28 periodically transmits the interrogation signal 108 to the platform 60 at the start of the search and receives the reply signal 108a, and receives the phase difference information 48, the return time information, and the geographical information. Based on 52 etc., the positioning information 54 of the platform 60 is generated and output to the platform 60.

  Further, the inertial navigation device 68 installed on the platform 60 generates acceleration information, velocity information, position information, and posture information when the search starts, and stores them in the storage unit 84. The speed information held in the inertial navigation device 68 is overwritten with the speed information input from the Doppler velocimeter 70, and the position information is overwritten with the positioning information 54 transmitted from the surface tracking buoy 28. Then, after the platform 60 has navigated the entire search range, the information on the reflected wave 92a, the information on the reflected wave 93a, the acceleration information, the speed information, the position information, and the attitude information stored in the storage unit 84 are transmitted to the wireless LAN terminal 14 ( PC) is stored in a storage area (not shown).

  Next, when the synthetic aperture processing is started, the synthetic aperture calculation processing unit 78 generates synthetic aperture processing information based on the information of the reflected wave 92a, position information, and posture information, and stores the storage area (not shown) of the wireless LAN terminal 14 (PC). ).

  Furthermore, by starting the interferometry calculation, the interferometry calculation unit 80 uses the synthetic aperture processing information, the information on the reflected wave 93a, the position information, and the posture information as described above to generate a high-frequency seabed image and a three-dimensional image. Information is generated and stored in a storage area (not shown) of the wireless LAN terminal 14 (PC). Of course, all the information stored in the storage area (not shown) of the wireless LAN terminal 14 (PC) can be drawn on a monitor (not shown) attached to the PC.

  Here, in order to generate a synthetic aperture image and a three-dimensional image generated from the synthetic aperture processing information with sufficient resolution, it is necessary to reduce the error of the position information. However, when the position information obtained by the inertial navigation system is used as in the prior art, the position information error (drift error) increases with time, so that sufficient resolution can be obtained in the synthetic aperture image and the three-dimensional image. Can not. However, in the present embodiment, the relative position information 50 between the surface tracking buoy 28 and the platform 60 is associated with the geographical information 52 based on the GPS positioning of the surface tracking buoy 28 and the attitude information 49 of the surface tracking buoy 28. The positioning information 54 is generated and overwritten on the position information held by the inertial navigation device 68. Therefore, the position information error does not increase with time, and the position error remains within the error range of the geographic information 52, the posture information 49, and the relative position information 50. Therefore, in the synthetic aperture image and the three-dimensional image, The resolution of the image can be increased.

  In this embodiment, the interrogation signal transmitter 64 transmits the interrogation signal 108 from the surface tracking buoy 28 forward in the traveling direction and obliquely downward. Therefore, it is preferable that the surface layer tracking buoy 28 is moved so as to come to a position where the platform 60 is tracked at a depression angle of 45 ° to 60 °.

  In the above-described embodiment, it has been described that the positioning information 54 by the SSBL method using the surface tracking buoy 28 equipped with the GPS receiver 40 is transmitted to the platform. However, the configuration in which the positioning information 54 described above is transmitted to the platform 60 side, the position information is updated, and the positioning information 54 with high resolution is secured is not limited thereto. For example, it is also possible to use a three-dimensional positioning method based on relative distance measurement using a floating body having positioning means in calculating the relative position between the surface tracking buoy and the platform. In this case, a plurality of surface tracking buoys serving as positioning means are provided, and positioning acoustic signals are transmitted to the platform, respectively, and return times of the reflected signals of the positioning acoustic signals are calculated. Then, the platform positioning information may be generated based on the geographical information based on the GPS positioning of each surface tracking buoy and the information on the return time of the reflected signal (distance between each surface tracking buoy and the platform). .

  For example, a reference first surface tracking buoy (not shown), other second surface tracking buoy (not shown), and third surface tracking buoy (not shown) are used. The first to third surface layer tracking buoys are arranged on the sea at regular intervals and generate geographic information based on GPS positioning. The first to third surface layer tracking buoys transmit first to third interrogation signals (positioning acoustic signals) having different frequencies from each other toward the platform. On the other hand, the platform 60 receives a first interrogation signal (not shown) that receives a first interrogation signal and outputs a first reply signal, and outputs a second interrogation signal after receiving the second interrogation signal. A second transponder (not shown) that receives the third interrogation signal and outputs a third reply signal is arranged. Here, the first to third return signals (reflection signals of positioning acoustic signals) have different frequencies. The first surface tracking buoy can receive only the first reply signal, the second surface tracking buoy can receive only the second reply signal, and the third surface tracking buoy can receive the third reply signal. Only to receive the signal.

  Each surface layer tracking buoy calculates a return time from when each interrogation signal is transmitted until each reply signal is received from each transponder. The second and third surface tracking buoys respectively transmit geographical information based on GPS positioning and return time information to the first surface tracking buoy. The first surface tracking buoy is based on the return time information calculated by each surface tracking buoy, the speed of sound in water, and the geographical information based on the GPS positioning of each surface tracking buoy. And the first relative position information of the platform is calculated. Then, the positioning information is generated by associating the information on the first relative position with the geographic information based on the GPS positioning of the first surface tracking buoy, and this may be transmitted to the platform.

  Each surface tracking buoy can generate posture information. For example, geographic information obtained by GPS positioning of each surface tracking buoy can be corrected by the posture information. Further, the reference surface tracking buoy and the surface tracking buoy for transmitting positioning information to the platform may be different from each other. Further, in order to suppress errors in the positioning information, in each surface layer tracking buoy, the above-described positioning information based on each surface layer tracking buoy may be generated, and the average value thereof may be transmitted to the platform side.

  On the other hand, in the first surface tracking buoy, the second surface tracking buoy and the platform are obtained by using the first relative position information and the geographical information based on the GPS positioning of the input second and third surface tracking buoys. The second relative position information is generated and transmitted to the second surface tracking buoy, and the third relative position information between the third surface tracking buoy and the platform is generated and transmitted to the third surface tracking buoy. Send.

  Each surface tracking buoy has a thruster attached to each surface tracking buoy based on the information on each relative position so that the relative position between each surface tracking buoy and the platform has a predetermined positional relationship. Adjust the output of. Thus, each surface layer tracking buoy can be tracked with a certain distance from the moving platform.

  In the above modification, geographical information based on GPS positioning is acquired for each surface tracking buoy, but the relative position between surface tracking buoys (positioning means) is fixed, or between surface tracking buoys (positioning means). If the relative position of can be measured, only one piece of geographic information based on GPS positioning is sufficient. For example, the elements (positioning means) for transmitting / receiving positioning acoustic signals are arranged at the tips of three arms extending in a direction perpendicular to each other from one surface tracking buoy, respectively, and the above-described three-dimensional positioning method based on relative distance measurement Using the same method to calculate the relative position with the platform (SBL: Short Base Line), the positioning information is calculated from the geographical information based on the GPS positioning of the surface tracking buoy and the relative position information by the SBL method. May be output to the platform side.

  It is also possible to perform platform positioning using three positioning means that do not track. In other words, the platform can be positioned with the positioning means fixed to the seabed. For example, the positioning means is fixed to the sea bottom as a landing structure, and the position is measured in advance to obtain position information of each positioning means. Then, in each positioning means, a return time (relative position with respect to the platform) until the inquiry signal is transmitted from each positioning means and a reply signal is received from the platform is calculated, and the position information of each positioning means and each positioning means From the calculated relative position, platform positioning information may be generated and output to the platform. Thereby, since each positioning means does not move, it is possible to generate the platform positioning information without using the GPS positioning information. In addition, when using a bottoming structure as a positioning means, it becomes a LBL (Long Base Line) system.

  In the present embodiment, as shown in FIG. 6, the interrogation signal 108 is transmitted from the surface layer tracking buoy 28 (interrogation signal transmitter 64), and the transponder 61 arranged in the platform 60 receives the response signal 108a. Has been described on the assumption that the surface tracking buoy 28 (transducer 32) receives the return signal 108a, but is not limited thereto. In other words, the transponder 61 is not disposed on the platform 60, the positioning acoustic signal (question signal 108) is transmitted from the surface tracking buoy 28, and the reflected signal of the positioning acoustic signal reflected by the platform 60 housing is reflected on the surface tracking buoy 28. A method in which the (transducer 32) receives may be used. That is, the reflected signal of the positioning acoustic signal corresponds to the return signal 108 a transmitted from the transponder 61. Therefore, the reflection signal of the positioning acoustic signal (question signal 108) is a reflection signal obtained by physically reflecting the housing of the platform 108, and the transponder 61 receives the inquiry signal 108 and transmits it in an information processing manner. Reply signal 108a to be included. In the present embodiment, the high-frequency transducer 76 that transmits and receives the second exploration wave 93 uses sound waves. However, an apparatus that can irradiate electromagnetic waves such as laser light as the second exploration waves may be used.

  In the present embodiment, it has been described that signals and information are exchanged between the surface tracking buoy 28 and the platform 60 using the communication signal 58, but the present invention is not limited to this. For example, the surface tracking buoy 28 and the platform 60 may be connected by a sufficiently long cable that does not interfere with the movement of the platform 60 to exchange signals and information. Similarly, exchange of signals and information between the surface tracking buoy 28 and the observation ship 12 may be performed not by the wireless LAN 16 but by connecting the surface tracking buoy 28 and the observation ship 12 with a cable.

Further, the platform 60 and the observation ship 12 are connected by a cable, and the information on the reflected wave 92a, the information on the reflected wave 93a, the acceleration information, the speed information, and the position information stored in the storage unit 84 are transmitted via the cable. The information may be stored in a storage area (not shown) of the wireless LAN terminal 14 (PC).
Thereby, the information memorize | stored in the memory | storage part 84 can be easily transmitted to the observation ship 12 side, without raising the platform 60. FIG. Of course, the information stored in the storage unit 84 may be transmitted to the observation ship 12 side via the communication signal 58 and the wireless LAN 16.

  In the present embodiment, the observation ship 12 and the surface tracking buoy 28 are used. However, all the components of the surface tracking buoy 28 are mounted on the observation ship 12, and the submarine acoustic image system 10 including the observation ship 12 and the platform 60 is provided. Also good. In this case, during the exploration by the platform 60, the observation ship 12 may stop the engine and track the platform 60 by the thruster 44. Here, it is assumed that the thruster 44 has a power for moving the observation ship and is designed to be sufficiently small so as not to affect the transmission / reception of the positioning acoustic signal. Then, the observation ship 12 serves as a positioning means to generate the positioning information of the platform 60 and transmit the positioning information to the platform 60.

  Furthermore, in this embodiment, the synthetic aperture calculation processing unit 78 and the interferometry calculation unit 80 have been described as being mounted in the wireless LAN terminal 14 (PC, monitor) arranged on the observation ship 12. However, the present invention is not limited to this, and it may be arranged on the platform 60 or mounted on a PC or the like in a land facility.

  Using the synthetic aperture technique and the interferometry technique, it can be used as a submarine acoustic image system capable of generating a high-resolution three-dimensional image of a seabed and an object on the seabed and a three-dimensional image of an object under the seabed.

10 ......... Submarine audio-visual system, 12 ......... Observation ship, 14 ......... Wireless LAN terminal, 16 ......... Wireless LAN, 28 ......... Tracking buoy, 30 ......... Wireless LAN terminal, 31 ... ... Control unit, 32 ... …… Transducer, 33 ......... Moving measurement device, 35 ......... Return time calculation unit, 36 ......... Relative position information calculation unit, 38 ......... Positioning information calculation unit, 40 ......... GPS receiver 42... Drive control unit 44... Thruster 46 46 acoustic modem 48 phase difference information 49 posture information 50 relative position information 52 ......... Geographic information, 54 ......... Positioning information, 56 ......... Output parameters, 58 ......... Communication signal, 60 ......... Platform, 60a ......... Plate, 61 ......... Transponder, 62 ......... Sound Modem, 64 ... Question signal transmitter, 6 ......... Image generation unit, 67 ......... Control unit, 68 ......... Inertial navigation device, 70 ......... Doppler speedometer, 72 ......... Transmitter, 74 ......... Receiving array, 76 ... ... High-frequency transducer, 78 ......... Synthetic aperture calculation processing unit, 80 ......... Interferometry calculation unit, 84 ......... Storage unit, 92 ......... First exploration wave, 92a ......... Reflected wave, 92b ......... Reflected wave, 92c ......... Submarine reflected wave, 92d ......... Submarine reflected wave, 93 ......... Second exploration wave, 93a ......... Reflected wave, 104 ... …… Camera, 106 ......... Depth gauge, 108 .... Question signal, 108a ... Reply signal, 112 ... ... Thruster.

Claims (10)

A transmitter attached to a platform for navigating in the sea, and irradiating a first exploration wave on the sea floor in a direction perpendicular to a direction in which the platform navigates;
A plurality of receivers attached to the platform, arranged in a direction perpendicular to the direction of navigation of the platform and intersecting the irradiation direction of the first exploration wave, each receiving a reflected wave of the first exploration wave. Waver,
A synthetic aperture calculation processing unit that generates synthetic aperture processing information from the reflected wave of the first exploration wave;
An inertial navigation device attached to the platform and generating position information of the platform;
The arrival angle of the reflected wave of the first exploration wave is calculated based on the phase difference between the reflected waves of the first exploration wave that has been subjected to the synthetic aperture processing that constitutes the synthetic aperture processing information, and the arrival angle and the position And an interferometry calculation unit that calculates a three-dimensional position of a reflection source of the reflected wave of the first exploration wave based on the information. The submarine audiovisual system according to claim 1,
The first exploration wave has a wavelength band that can be transmitted below the sea floor;
The synthetic aperture processing information is
Information on the bottom reflected wave reflected on the bottom of the sea and information on the bottom reflected bottom reflected on the bottom of the sea,
The interferometry computing unit is
Based on the time difference of the arrival time of the submarine reflected wave and the seafloor reflected wave having the same angle of arrival as the submarine reflected wave from the synthetic aperture processing information, the seabed Extracting the information of the surface reflected wave and the information of the submarine reflected wave respectively and generating the information of the time difference,
By calculating the reflection position of the reflected sea bottom wave having the same angle of arrival as the reflected wave under the sea floor, information on the passing position on the sea floor of the reflected sea bottom wave is calculated.
A submarine acoustic video system capable of calculating a three-dimensional position of a reflection source of the submarine reflected wave based on the position information, the passing position information, and the time difference information. The submarine audiovisual system according to claim 2,
A second exploration wave attached to the platform and reflected from the sea floor is irradiated in a direction perpendicular to the navigation direction of the platform and in a direction intersecting the irradiation direction of the first exploration wave, and the second exploration wave It has a high-frequency transducer that receives reflected waves,
The interferometry calculation unit extracts information on the submarine reflected wave from the synthetic aperture processing information using high-frequency bottom information generated from the reflected wave of the second exploration wave. Video system. The submarine audiovisual system according to any one of claims 1 to 3,
Three or more receivers are arranged in a direction perpendicular to the direction in which the platform navigates and in a direction intersecting the irradiation direction of the first exploration wave. The submarine audiovisual system according to any one of claims 1 to 4,
Positioning means is disposed on the sea, transmits a positioning acoustic signal to the platform, receives a reflected signal of the positioning acoustic signal reflected from the platform, and calculates information on a relative position with respect to the platform. And
The positioning means generates positioning information of the platform based on the information on the relative position and geographic information of the positioning means based on GPS positioning, and outputs the generated positioning information to the inertial navigation device,
The submarine acoustic image system, wherein the inertial navigation device updates the position information with the positioning information. The submarine audiovisual system according to claim 5,
The positioning means is
Receiving a reflected signal of the positioning acoustic signal and detecting a phase difference in three directions orthogonal to each other of the reflected signal, and generating information on the relative position based on the phase difference A submarine audiovisual system. The submarine audiovisual system according to any one of claims 1 to 4,
A plurality of positioning means arranged on the sea and transmitting positioning acoustic signals to the platform, respectively, and calculating return times of the reflected signals of the positioning acoustic signals reflected from the platform;
Any one of the plurality of positioning means includes: information on the return time calculated by each positioning means; and geographic information based on GPS positioning of at least one of the plurality of positioning means. Based on the generated positioning information of the platform and output to the inertial navigation device,
The submarine acoustic image system, wherein the inertial navigation device updates the position information with the positioning information. The submarine audiovisual system according to any one of claims 1 to 7,
A transponder is arranged on the platform,
The transponder receives the positioning acoustic signal as a question signal and transmits a return signal as a reflection signal of the positioning acoustic signal. The submarine audiovisual system according to any one of claims 5 to 8,
The positioning means is
An actuator for moving the positioning means;
A submarine acoustic image system characterized in that the output of the actuator can be adjusted so that the relative position between the platform and the positioning means is constant. The submarine audiovisual system according to any one of claims 1 to 4,
A plurality of positioning means for transmitting each of the positioning acoustic signals to the platform and calculating return times of the reflected signals of the positioning acoustic signals reflected from the platform are fixed to the seabed,
Based on the return time information calculated by each positioning means and the position information of each positioning means, the platform positioning information is generated and output to the inertial navigation device,
The submarine acoustic image system, wherein the inertial navigation device updates the position information with the positioning information.