JP2022157362A - Sonar system, target azimuth/distance correction method, and program - Google Patents

Abstract

To allow for reducing errors in azimuth of and distance to a target identified in data received form a line array.SOLUTION: A tilt of a line array consisting of multiple reception elements in a depth direction is detected to correct an error arising due to the tilt of a towed sonar in the depth direction relative to an azimuth to and a direction of a target identified by data received from the line array.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sonar system, a target azimuth/distance correction method, and a program.

Sonar is a device that uses sound waves to identify the position of underwater objects, etc. Underwater acoustic information is obtained based on signals received by an array of multiple receiving elements (wave receivers) that convert received sound waves into electrical signals. get A towed sonar generally has a line array in which a plurality of receiving elements are arranged in a straight line at the end of a cable extending from a platform of a ship or the like. Variable Depth Sonar (VDS) among towing sonars has the advantage that the towing depth is variable according to the underwater sound wave reception conditions.

In Patent Document 1, a sonar (sonar) device includes an array of a plurality of hydrophones suspended from a buoy monitor device, and a sensor unit attached to the bottom of the hydrophone, and the sensor unit is connected to the hydrophone. Depth, water temperature, salinity, and azimuth inclination at the bottom of the phone are detected, and the detected information is transmitted to the signal processing unit together with sonar information from underwater objects. is disclosed. Depth data and azimuth gradient data are used to improve the positioning accuracy of hydrophones and underwater objects.

JP-A-07-198844

In a general towed sonar in which a line array is towed by a ship or the like, the receiving directivity is conical (conical beam), as schematically shown as a directivity image 12 in FIG. 1(A), for example. That is, the reception beams formed by performing phasing addition processing or the like on the reception signals at the reception element rows constituting the line array of the towed sonar 10 have a beam pattern that spreads conically like the directional image 12 . FIG. 1(A) shows a side view (X -Z plane) is a schematic side view. In FIG. 1A, the north side is the X-axis positive side, the south side is the X-axis negative side, the sea surface side is the Z-axis positive side, and the seabed side is the Z-axis negative side. FIG. 1B is a schematic plan view of the underwater towed sonar 10 and target 11 (underwater object) shown in FIG.

As shown in FIG. 1A, when the depth (target depth 14) of the target 11, which is an underwater object, is different from the towed sonar depth 13, which is the depth of the towed sonar 10, as shown in FIG. , an error occurs between the observed azimuth 15 and the actual azimuth 16 of the target 11 . For example, if the depth of the target 11 (target depth 14) is greater than the towed sonar depth 13, the projection of the conical receive beam pattern onto the XY plane at the towed sonar depth 13 (Z-axis coordinate = 0) The orientation corresponding to the left hypotenuse of an inverse isosceles triangle (directional image 12) is taken as the observation orientation 15, but the actual orientation 16 of the target 11 is inside the orientation of the left hypotenuse of the inverse isosceles triangle. .

FIG. 2A schematically shows a case where the towed sonar 10 itself is tilted in the depth direction due to an external force such as an ocean current. FIG. 2(A) is a schematic side view schematically showing the XZ plane when viewing the towed sonar 10 in the sea from west to east (from the Y-axis negative direction to the positive direction), similar to FIG. 1(A). is. The line array of towed sonar 10 is tilted about the Y-axis by a pitch angle α, and the conical directional image 12 is similarly tilted by a pitch angle α. Here, the pitch angle α is positive when counterclockwise around the Y-axis. It should be noted that the beam is flattened (disk-like) at 90 degrees normal to the traveling direction (the north side of the positive value of the X axis) (directivity image 12A). In FIG. 2A, the origin of the three-dimensional coordinate system XYZ (left-handed system) is the acoustic center of the towed sonar 10 (for example, the center of the line array). , the Y-axis is negative on the west side (upper side perpendicular to the paper surface) and positive on the east side (back side perpendicularly to the paper surface), and the Z-axis is positive on the sea surface side and negative on the sea bottom side.

FIG. 2B is a schematic plan view of the underwater towed sonar 10 and target 11 (underwater object) shown in FIG. The received beams based on the received data from the line array tilted at the pitch angle α about the Y axis are represented by the three-dimensional coordinates obtained by rotating the three-dimensional coordinate system XYZ about the Y axis by the angle α, as shown as a directional image 12. In the system X'YZ' (left-handed system), the beam pattern spreads conically with the X' axis as the central axis. Although the actual target 11 is located on the YZ plane with X=0 in the three-dimensional coordinate system XYZ as shown in FIG. 2(A), in the example of FIG. , the target 11A observed based on the received data from the line array is the left end of the inverted isosceles triangle (height=a) obtained by projecting the directional image 12 onto the X'-Y plane. That is, the target 11A to be observed is observed on the YZ' plane where the X' axis value is a, and the observation azimuth 15 is half the apex angle of the inverted isosceles triangle (directional image 12). Thus, an error occurs between the observed bearing 15 and the actual bearing 16, and an error occurs in the distance between the observed target 11A and the actual target 11. FIG. These errors adversely affect the sonar's measurement performance.

The present invention was invented in view of the above problems, and its object is to provide a sonar system capable of reducing target azimuth error and range error specified by data received from a line array, and a target azimuth/distance error. An object is to provide a correction method and a program.

According to the present invention, means for detecting a tilt in the depth direction of a line array composed of a plurality of receiving elements is provided. A sonar system is provided that includes azimuth and distance correction means for correcting an error caused by the tilt of the line array in the depth direction.

According to the present invention, the tilt in the depth direction of a line array composed of a plurality of receiving elements is detected, and the towing-type sonar detects the azimuth and distance of a target specified by the data received from the line array. A target azimuth/distance correction method is provided that corrects errors caused by tilt in the depth direction.

According to the present invention, the computer of the sonar system detects the tilt in the depth direction of a line array composed of a plurality of receiving elements, and detects the target azimuth and distance specified by the data received from the line array. , a program for executing a correction process for correcting an error caused by a tilt of the towed sonar in the depth direction. Furthermore, according to the present invention, a computer-readable recording medium (for example, RAM (Random Access Memory), ROM (Read Only Memory), or EEPROM (Electrically Erasable and Programmable ROM) or other semiconductor storage, HDD (Hard Disk Drive), SSD (Solid State Drive), CD (Compact Disc), DVD (Digital Versatile Disc), and the like.

According to the present invention, it is possible to reduce the azimuth error and range error of the target specified by the data received from the line array.

(A) and (B) are diagrams for schematically explaining a related technology. (A) and (B) are diagrams for schematically explaining a related technology. It is a figure explaining embodiment of this invention. It is a figure explaining an example of the device configuration of the embodiment of the present invention. It is a figure explaining an example of the device configuration of the embodiment of the present invention. FIG. 2 illustrates a method of an embodiment of the invention; It is a figure which shows one Example of this invention. It is a figure which illustrates the structure of embodiment of this invention.

An embodiment of the present invention will be described. FIG. 3 is a diagram illustrating an embodiment of the present invention. In FIG. 3A, as in FIG. 2A, the acoustic center position of the towed sonar 20 is the origin of the three-dimensional coordinate system XYZ (left-handed system). On the Y axis, the west side (upper side perpendicular to the paper surface) is negative and the east side (back side perpendicular to the paper surface) is positive, and the Z axis is positive on the sea surface side and negative on the sea bottom side. FIG. 3A schematically shows the XZ plane viewed from the Y-axis negative side. FIG. 3B schematically shows the XY plane viewed from the positive side of the Z axis in FIG. 3A. Note that the three-dimensional coordinate system XYZ (left-handed system) is for illustration purposes only, and it goes without saying that a right-handed system may also be used. Moreover, of course, this does not mean that the traveling direction of the towed sonar 20 is limited to the north side.

A computer device mounted on a ship equipped with a towed sonar 20 and a transmitting sound source and functioning as a sonar system controller provides the towed sonar with a search target depth 24, which is depth information of a target to be searched (underwater object), It is set in advance from an operation terminal or the like (not shown).

The towed sonar 20 is equipped with a sensor (for example, an attitude sensor) that detects attitude information (angle of the line array in the longitudinal direction (pitch angle)). The computer device calculates an array pitch angle α, which is the inclination of the line array in the depth direction (the pitch angle around the Y-axis in FIG. 3A), based on the orientation information from the sensor. For example, multiple depth sensors are mounted at different locations on a towed sonar 20 line array. It is assumed that the computer device can obtain the angle (array pitch angle) at which the towed sonar 20 is tilted in the depth direction from the depth information at an arbitrary time.

The computer device corrects the azimuth and distance of the target (underwater object) specified by the data received from the line array of the towed sonar 20 from the search target depth 24 and the array pitch angle α, and corrects the azimuth and distance reduce the error of That is, the computer device uses the search target depth 24 and the array pitch angle α to determine the acoustic center position of the towed sonar 20 from the target azimuth and distance specified by the data received from the line array of the towed sonar 20. The three-dimensional coordinates (XYZ coordinates) of the target position with the origin are obtained.

The computer device outputs the azimuth and distance horizontally projected from the determined three-dimensional coordinates onto the two-dimensional coordinates (XY plane) as the target position.

By performing the above processing, the computer device corrects an error caused by the directivity of the line array of the towed sonar 20 being conical (conical beam).

FIG. 4 is a diagram illustrating an embodiment of the present invention. In FIG. 4, the towed sonar 104 corresponds to the towed sonar 20 in FIG. Receives sound waves reflected from and converts them into electrical signals. In a towed sonar 104, at least two depth sensors 106A, 106B are mounted a predetermined distance (L) from each other along the length of the line array.

The transmission control device 101 controls the transmission sound source 102 and transmits the control information to the reception processing device 103 . The transmission control device 101 generates an electric signal from information such as the waveform of the sound wave received from the display device 105 and the transmission time, and outputs the electric signal to the transmission sound source 102 . The transmission control device 101 also outputs information such as the waveform of the sound wave and the transmission time to the reception processing device 103 .

The transmission sound source 102 is a device that generates sound waves, converts an electric signal (transmission signal waveform) sent from the transmission control device 101 into an acoustic signal, and transmits the sound waves underwater.

The towed sonar 104 receives the acoustic signal reflected from the target (underwater object) with respect to the sound wave transmitted from the transmission sound source 102 by the receiving element array (line array), converts it into an electric signal, and outputs it to the reception processing device 103. Send to In addition, the towed sonar 104 transmits the depth information of two points detected by the depth sensor to the reception processing device 103 at predetermined intervals, for example. Received signals from the towed sonar 104 and depth information are transmitted to the receiver and processor 103 of the sonar system mounted on the ship via a cable for towing (not shown).

The reception processing device 103 receives transmission information from the transmission control device 101 (for example, transmission timing, transmission waveform replica signal, etc.), the reception signal received by the receiving element array of the towed sonar 104, and the depth sensor 106A of the towed sonar 104. , 106B and the search target depth, calculations are performed to correct the azimuth and distance information of the target, and the calculation results are output to the display device 105 . The reception processing unit 103 uses the depth of the search target and the tilt angle of the line array in the depth direction to determine the direction and distance of the target specified by the data received from the receiving element array (line array) of the towed sonar 104. The three-dimensional coordinates (XYZ coordinates) of the target position with the acoustic center position of the towed sonar 104 as the origin are obtained, and the azimuth and distance projected horizontally from the three-dimensional coordinates onto the two-dimensional coordinate plane (XY plane) are calculated. Output as target position.

The display device 105 (terminal device) converts the data output from the reception processing device 103 into image information or the like and displays the image information. The display device 105 also has a function of setting information (waveform information, transmission timing, etc.) of sound waves to be transmitted from the transmission sound source 102 and transmitting the information to the transmission control device 101, and inputting a search target depth. From an input device (not shown) of the display device 105, the person in charge inputs information such as the waveform of the sound wave to be transmitted by the transmission sound source 102 and the transmission time, and also inputs the search target depth.

FIG. 5 is a functional block diagram for explaining the processing performed by the reception processing device 103. As shown in FIG. In FIG. 5, a phasing processing unit 1032 inputs N pieces of received data 1031 from N receiving elements 1 to N constituting the line array of the towed sonar 104, performs phasing processing, and performs phasing processing. A phase processing result is output to the signal processing unit 1033 .

The signal processing unit 1033 extracts echoes of the target (underwater object) using correlation processing or the like on the phasing processing result received from the phasing processing unit 1032 .

Since the transmission time and position of the transmission sound source 102 and the position of the towed sonar 104 are known, the azimuth and distance of the reflected sound (echo) are geometrically calculated.

The signal processing _{unit 1033 calculates} the three-dimensional coordinates ( coordinates in the three-dimensional coordinate system XYZ in FIG. 3A).

・・・(1) Suppose a towed sonar 104 (a line array) is equipped with at least two depth sensors 106A, 106B with a spacing between them of L[m]. When the pitch angle (array pitch angle) of the line array with respect to the acoustic center position of the towed sonar 20 is α, the depth at the depth sensor 106A is d ₁ [m] (positive: seabed direction), and the depth at the depth sensor 106B is Assuming that the depth is d ₂ [m] (d ₁ >d ₂ ), since the inclination of the depth sensors 106A and 106B with respect to the horizontal axis is α, the depth difference=d ₁ −d ₂ =Lsin(α) Therefore, the array pitch angle α is given by the following equation (1).

...(1)

The azimuth/distance correction unit 1034 calculates the array pitch angle α from equation (1). The azimuth/distance correction unit 1034 calculates the search target depth d _ss with the acoustic center position of the towed sonar as the reference (0 m) from the information of the depth sensors 106A and 106B and the search target depth 24 (FIG. 3A). do.

The azimuth θ _T ' and the distance r _T ' of the target 21 specified by the N received data from the towed sonar 20 (the N receiving elements of the line array) are expressed in the three-dimensional coordinate system X This is the value obtained by 'YZ'. The three-dimensional coordinate system X'YZ' is obtained by rotating the three-dimensional coordinate system XYZ around the Y-axis by a pitch angle α. The position (x', y', z') of the target 21 in the three-dimensional coordinate system X'YZ' is given below.

・・・(2)

...(2)

・・・(3) However, φ is given by the following equation.

...(3)

In equation (2), the azimuth θ _T ' of the target 21 is the counterclockwise angle from the X' axis in the X'-Y plane. In left-handed coordinates, the counterclockwise angle from the X' axis on the X'-Y plane is negative, but for the sake of simplicity, the orientation θ _T ' is assumed to be a positive value. In FIG. 3A, the target 21 is considered as a vector of length (distance) r _T ' from the origin (acoustic center position of the towed sonar 20), and the projection (projection) value x' of the vector onto the X' axis is is given by r _T 'cos(θ _T '), and the angle φ is the component of length r _T 'sin(θ _T ') orthogonal to the projection r _T 'cos(θ _T ') onto the X' axis. vector) onto the YZ' plane and the angle formed by the Y axis. Therefore, the projection value y' on the Y axis (negative on the west side) is -r _T 'sin(θ _T ')·cos(φ), and the projection value z' on the Z axis is -r _T 'sin(θ It is given by _T ')·sin(φ).

In equation (3), the numerator of the arcsine function sin ⁻¹ is the projection value r _T 'cos(θ _T ') of the distance r _T ' of the target 21 onto the X' axis projected onto the Z axis (negative side). It is a value obtained by adding the search target depth d _ss (<0) to (r _T 'cos(θ _T ')·sin(α)>0). The denominator is a value obtained by multiplying r _T 'sin(θ _T ') by cos(α), and since the numerator is a negative value and the angle φ is a non-negative value, a minus sign is attached.

・・・(4)
を施してＸＹＺ座標系での座標値に変換する。 Azimuth/distance correction unit 1034 applies transformation matrix R(- α):

···(Four)
to convert to coordinate values in the XYZ coordinate system.

・・・(5)

···(Five)

・・・(6) From equation (5),

...(6)

The azimuth/distance correction unit 1034 calculates the coordinates (x, y, z) of the target 21 in the three-dimensional coordinate system XYZ using the above equation (6).

Subsequently, the azimuth/distance correction unit 1034 calculates the positional coordinates (x, y, z) of the target 21 in the three-dimensional coordinate system XYZ, using the following equations (7) and (8), the X A direction θ _t (25 in FIG. 3B) and a distance r _t (26 in FIG. 3B), which are coordinates (x, y) projected onto the −Y plane, are obtained.

・・・(7)

...(7)

・・・(8)

...(8)

In equation (7), since the direction θ _t is a non-negative value, in the calculation of tan ⁻¹ , the Y coordinate value of the target 21: y (negative value) is −y. When the azimuth θ _t indicated by 25 in B) is a negative value, (−y/x) in Equation (7) becomes (y/x).

The azimuth/distance correction unit 1034 outputs the azimuth θ _t and the distance r _t of the target 21A projected onto the two-dimensional XY plane as final processing results.

According to this embodiment, by using the search target depth 24 and the array pitch angle α of the towed sonar 20, the azimuth and distance of the target 21 (underwater object) identified by the towed sonar 104 are corrected, and the error is reduced. can do.

FIG. 6 is a diagram for explaining the method of this embodiment. The reception processing device 103 calculates the azimuth/distance of the target from the reception data of the line array (step S11).

The reception processing device 103 calculates an array pitch angle α, which is the pitch angle (inclination in the depth direction) of the line array, from the orientation information of the line array (depth sensor, sensing information from the orientation sensor) (step S12). Either of steps S11 and S12 may be performed first.

Using the input search target depth 24 and array pitch angle α, the reception processing unit 103 uses the acoustic center position of the towed sonar 20 as the origin from the azimuth and distance of the target specified from the received data of the line array. The three-dimensional coordinates (XYZ coordinates) of the position of the target are obtained by arithmetic processing (step S13).

The reception processing device 103 outputs the azimuth 25 and the distance 26 obtained by projecting the three-dimensional coordinates obtained in step S13 onto the two-dimensional coordinates (XY plane) as the position of the target 21 (step S14).

FIG. 7 is a diagram illustrating an example. The effect of applying the embodiment to the towed sonar detection information (azimuth and distance) obtained when the search target depth 24 is 100m (towing sonar depth standard) and the array pitch angle is 10° is shown. It is. In FIG. 7, the graph is plotted with the acoustic center position of the towed sonar as the origin, and the detected azimuth and distance obtained by the towed sonar and the detected azimuth and distance corrected by applying the present invention are developed into plane coordinates. It is.

When there is a depth difference between the towed sonar and the target, the directivity (conical beam) of the towed sonar causes the actual azimuth to be closer to the origin than the observed azimuth, but this property has been corrected. I know there is. The search target depth can be obtained not only by an operation terminal or the like, but also by a method of storing it in advance in a storage device or the like and arbitrarily reading it.

FIG. 8 is a diagram for explaining an embodiment of the present invention, and is a diagram for explaining the configuration when the reception processing device 103 is implemented in the computer device 110. As shown in FIG. Referring to FIG. 8, the computer device 110 includes a processor 111, semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), and HDD (Hard Disk Drive). etc., a display device 105 , and an interface 114 for communication connection with the towed sonar 104 and the display device 105 . The processor 111 may be a DSP (Digital Signal Processor). By reading and executing the program 113 stored in the storage device 112, the processor 111 performs each processing of the phasing processing unit 1032, the signal processing unit 1033, and the azimuth/distance correction unit 1034 of the reception processing device 103 in FIG. Run. Note that the computer device 110 may implement the functions of the transmission control device 101 in FIG.

In the above embodiment, the tilt in the depth direction of the towed sonar is an example of using two depth sensors, but it is also possible to calculate the tilt using a plurality of depth sensors. Also, any sensor that can obtain posture information, such as an acceleration sensor, can be used. In addition, FIG. 4 shows an embodiment of a line array towed from a warship, but the present invention can be widely used in the case of a line array with conical receiving directivity.

The disclosure of Patent Document 1 above is incorporated herein by reference. Within the framework of the full disclosure of the present invention (including the scope of claims), modifications and adjustments of the embodiments and examples are possible based on the basic technical concept thereof. Also, various combinations and selections of various disclosure elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) are possible within the scope of the claims of the present invention. . That is, the present invention naturally includes various variations and modifications that can be made by those skilled in the art according to the entire disclosure including claims and technical ideas.

10, 20 towed sonar 11, 11A, 21, 21A targets 12, 12A, 22 directional images 13, 23 towed sonar depth 14 target depth 15 observation azimuth 16 actual azimuth 24 search target depth 25 azimuth 26 range 101 transmission control Device 102 Transmission sound source 103 Reception processing device 104 Towed sonar 105 Display device 110 Computer device 111 Processor 112 Storage device 113 Program 114 Interfaces 106A and 106B Depth sensor 1031 Received data 1032 Phase adjustment processing unit 1033 Signal processing unit 1034 Azimuth/distance correction unit

Claims (9)

comprising means for detecting a tilt in the depth direction of a line array composed of a plurality of receiving elements; and
A sonar system comprising azimuth/distance correcting means for correcting an error caused by tilt of the line array in the depth direction with respect to the target azimuth and distance specified by the data received from the line array. wherein the line array is a towed sonar line array;
comprising means for inputting a search target depth of said target;
The azimuth/distance correction means calculates the acoustic center position of the towed sonar using the search target depth set and input in advance with respect to the azimuth and distance of the target specified by the received data from the line array. 2. The sonar system of claim 1, wherein the sonar system of claim 1 corrects for errors caused by differences between the depth of the target and the depth of the target. comprising at least two depth sensors spaced apart from each other on the towed sonar;
The azimuth/distance correction means is
calculating an array pitch angle, which is a tilt in the depth direction, from the depth information detected by the depth sensor;
Using the search target depth and the array pitch angle, the azimuth and distance of the target specified by the data received from the line array are used to determine three possible positions of the target with the acoustic center of the towed sonar as the origin. find the dimensional coordinates,
3. The sonar system of claim 2, outputting bearing and distance projected from said three-dimensional coordinates to two-dimensional coordinates. Detecting the tilt in the depth direction of a line array composed of multiple receiving elements,
A target azimuth/distance correcting method for correcting an error caused by tilt in the depth direction of the towed sonar with respect to the target azimuth and distance specified by the data received from the line array. wherein the line array is a towed sonar line array;
inputting a set value for the target search depth;
An error caused by a difference between the depth of the acoustic center position of the towed sonar and the depth of the target is preset and input with respect to the azimuth and distance of the target specified by the data received from the line array. 5. The target azimuth/distance correction method according to claim 4, wherein correction is performed using a search target depth. mounting at least two spaced apart depth sensors at the same height on the towed sonar;
calculating an array pitch angle, which is a tilt in the depth direction, from the depth information detected by the depth sensor;
Using the search target depth and the array pitch angle, the azimuth and distance of the target specified by the data received from the line array are used to determine three possible positions of the target with the acoustic center of the towed sonar as the origin. find the dimensional coordinates,
6. The target azimuth/distance correction method according to claim 5, wherein the azimuth and distance projected from the three-dimensional coordinates onto the two-dimensional coordinates are output as the target position. on the sonar system computer,
a process of detecting a tilt in the depth direction of a line array composed of a plurality of receiving elements;
Correction processing for correcting an error caused by the tilt of the line array in the depth direction with respect to the target azimuth and distance specified by the data received from the line array;
program to run. wherein the line array is a towed sonar line array;
In the correction process, an error caused by a difference between the depth of the acoustic center position of the towed sonar and the depth of the target is corrected in advance with respect to the azimuth and distance of the target specified by the data received from the line array. 8. The program according to claim 7, wherein correction is performed using the set and input target search depth. The correction process uses the array pitch angle, which is the inclination in the depth direction, from depth information detected by at least two depth sensors attached to the towed sonar with a space from each other, and the depth of the search target, to determine the line Obtaining three-dimensional coordinates of the position of the target with the acoustic center position of the towed sonar as the origin from the azimuth and distance of the target specified by the data received from the array;
9. The program according to claim 8, wherein the azimuth and distance projected from the three-dimensional coordinates to the two-dimensional coordinates are output as the target position.

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