KR20180096482A - Method for analyzing motion of underwater target - Google Patents

Abstract

Disclosed is a method for analyzing motion of an underwater target. The method for analyzing motion of an underwater target comprise the steps of: a first signal receiving step that a line array sonar is towed along a first movement path and receives a signal generated in an underwater target; a second signal receiving step that the line array sonar is towed along a second movement path in a direction different from the first movement path and receives the signal generated in the underwater target; and a target motion analysis step of analyzing the motion of the underwater target from the signal received in the linear array sonar.

Description

[0001] The present invention relates to a method for analyzing underwater targets,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing underwater target motion, and more particularly, to a method for analyzing motion of an underwater target using a line array sonar.

As a means to detect underwater targets (whales, submarines, etc.), a sonar system using sound waves is operated, which is divided into active sonar systems that detect the target by emitting sound waves and passive sonar systems that detect the radiated noise from the target do. A passive sonar system is the most widely used linear array sonar system in which acoustic sensors are linearly arranged.

Such a linear array sonar system basically detects the orientation of the target through a beam forming technique and performs a target motion analysis (TMA) using the orientation of the target. For this purpose, the orientation detection technique and the target motion analysis technique of the linear array sonar have been studied.

The azimuth detected in the existing line array sonar assumes a plane wave condition in which the signal of the target reaches a straight path on the horizontal plane. However, in the actual ocean environment, the signal of the target is caused by the vertical sound velocity structure which changes according to the water temperature, refraction and reflection phenomenon due to the influence of the water depth and the submarine bottom, and accordingly, do.

The received signal has an error compared with the target orientation calculated by the plane wave condition on the existing horizontal plane due to the refraction and reflection, and if the target motion analysis is performed using the signal having such an error, the inaccurate result It is likely to be derived. Therefore, it is necessary to correct the error due to the multipath propagation phenomenon and to use a suitable target motion analysis technique.

The present invention provides a method for analyzing an underwater target motion that can confirm whether a bearing received by a linear array sonar has propagated through any multipath.

The present invention also provides an underwater target motion analysis method capable of performing accurate target motion analysis according to a multipath signal received in a linear array sonar.

A method for analyzing an underwater target motion according to the present invention includes a first signal receiving step in which a line array sonar is traversed along a first movement path and receives a signal generated in an underwater target; A second signal receiving step in which the line array sonar is traversed along a second movement path in a direction different from the first movement path and receives a signal generated in the underwater target; And a target motion analysis step of analyzing the motion of the underwater target from the signal received in the linear array sonar.

In addition, the detection orientation of a signal received in the linear array sonar may include an actual detection orientation and a false detection orientation, and the target motion analysis step may include a detection orientation of the signal received in the first signal reception step, Wherein the detection direction of the signal received in the receiving step is accumulated over time, and in the section where the line array sonar changes from the first travel route to the second travel route, the detection direction having a relatively large rate of change is referred to as the false detection direction , And it is possible to determine the detection orientation having a relatively small rate of change as the actual detection orientation.

Also, the signal received in the line array sonar may include a sea level reflection signal received after being reflected on the sea surface, a sea floor reflection signal received after being reflected on the sea floor, a signal received with the diameter not reflected on the sea level or the sea floor Wherein the target motion analyzing step accumulates the actual detection orientation of the signal received at the first signal receiving step and the actual detection orientation of the signal received at the second signal receiving step with respect to time, When the rate of change of the actual detection orientation changes during the transition period in the section where the line array sonar changes from the movement route to the second movement route, the signal can be determined as the bottom floor reflection signal.

The target motion analyzing step may set an interval between the detection orientation of the signal determined as the bottom surface reflection signal and the linear array sonar as a target area in which the underwater target can be located, Wherein the unit target orientations are divided into a plurality of groups by a predetermined azimuth unit to calculate arrival angles of signals received in the line array sonar for each of the unit target orientations, It is possible to calculate the distance at which the sea floor reflection signal reaches the expected water depth of the underwater target, display the calculated distance for each unit target orientation, and linearize the display points to generate the target expected diagonal line.

Also, the target expected diagonal line may be generated as a curve.

Also, the target motion analyzing step may include calculating a detection orientation of a signal received in the linear array sonar and an arrival angle of a signal received in the linear array sonar, and determining a target orientation of the underwater target from the detection orientation and the arrival angle Can be estimated.

In addition, it may include a computer-readable recording medium on which a program for performing the above-described underwater target motion analysis method is recorded.

According to the present invention, the actual detection orientation can be identified through the transition of the sonar array sonar.

Also, according to the present invention, it is possible to identify the bottom surface reflection signal of the multi-path signal through the transition of the line array sonar.

Further, according to the present invention, when the detection orientation is identified as the undersurface reflection signal, the target target bearing line of the curve can be applied to perform accurate target motion analysis.

1 is a flowchart illustrating a method of analyzing a motion of an underwater target according to an embodiment of the present invention.
2 is a diagram showing signals received in a line array sonar.
FIG. 3 is a diagram illustrating an average vertical sound velocity structure and a transmission loss of a sound wave according to the embodiment of the present invention in a sea area of 60 NM in Ulleung, Korea.
FIG. 4 is a diagram illustrating a change in multipath propagation according to a distance change in a marine environment according to FIG.
5 is a graph showing the characteristics and the conical angle of the linear array sonar.
6 is a diagram showing the correlation between the detection azimuth, the arrival angle, and the actual target azimuth of the signal received in the line array sonar.
7 is a table showing an example of Eigenray info of the Bellop model based on the sound line theory.
8 to 10 are graphs showing the accumulation of errors between the detection orientation and the target orientation using the arrival angles obtained from Eigenray info for each of the multipath signals.
11 is a graph illustrating accumulation and display of a detection direction of a received signal according to movement of a linear array sonar according to an embodiment of the present invention over time.
12 is a graph illustrating accumulation and display of detection signals of received signals according to movement of a linear array sonar according to a comparative example of the present invention over time.
13 is a graph showing a process of estimating the actual target orientation of the target through the actual detection orientation of the signal with the diameter and the sea level reflection signal.
14 is a graph showing a process of estimating the actual target orientation of the target through the actual detection orientation of the sea floor reflection signal.
15 is a diagram illustrating a method of generating a target anticipation line according to an embodiment of the present invention.
FIG. 16 is a graph of the motion of the target with the target expected diagonal line generated according to the method of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof. Also, in this specification, the term "connection " is used to include both indirectly connecting and directly connecting a plurality of components.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a flowchart illustrating a method of analyzing a motion of an underwater target according to an embodiment of the present invention.

Referring to FIG. 1, a method for analyzing motion of an underwater target receives a signal generated from an underwater target through a linear array sonar, and analyzes the motion of the underwater target through analysis of the received signal. Specifically, the method for analyzing a motion of an underwater target includes a first signal receiving step (S10), a second signal receiving step (S20), and a target motion analyzing step (S30).

The first signal receiving step (S10) traps the line array sonar to the first movement path and receives signals generated in the underwater target. The first signal receiving step (S10) receives the signal during the towing time and accumulates the signal.

The second signal receiving step (S20) towes the line array sonar to the second movement route and receives signals generated in the underwater target. The second movement path is a path that is different from the first movement path and the moving direction, and the path of the linear array sonar is veering in a section where the first movement path is switched to the second movement path. The second signal reception step (S20) receives the signal during the towing time and accumulates the signal.

The target motion analysis step S30 analyzes the motion of the underwater target from the signal received in the linear array sonar in the first signal reception step S10 and the second signal reception step S20.

Hereinafter, the process of analyzing the motion of the underwater target in the target motion analysis step will be described in detail.

2 is a diagram showing signals received in a line array sonar.

Referring to FIG. 2, the signals S1, S2, and S3 generated in the underwater target 200 are received in the line array sonar 100 through multiple paths. Specifically, the signal received in the line array sonar 100 is a signal that is generated in the underwater target 200 and arrives only through the underwater path without being reflected on the sea surface (OS) or the sea floor OB A surface reflect path signal S2 generated by the underwater target 200 and reflected by the sea surface OS and arriving at the underwater target 200; And a bottom bounce path signal (S3).

FIG. 3 is a diagram illustrating an average vertical sound velocity structure and a transmission loss of the sound waves according to the present invention in a sea area of 60NM in Ulleung North, FIG. 4 is a graph showing a change in multi- Fig.

2 to 4, since the above-described multipath signals S1, S2, and S3 are transmitted through different paths, the detection directions of the signals S1, S2, and S3 received in the linear array sonar 100 Are different for each path. Particularly, in the case of the bottom surface reflection signal S3, the sea level reflection signal S2 and the angle of arrival, which is a vertical angle with respect to the signal S1, are large, which may have a large error in consideration of the characteristics of the line array sonar .

In order to correct such an error, it is necessary to firstly check whether the signals S1, S2, S3 received by the line array sonar 100 are propagated through. When each path is classified, a target motion analysis method .

5 is a graph showing the characteristics and the conical angle of the linear array sonar.

As shown in FIG. 5A, the linear array sonar 100 has a directional ambiguity in the detection direction of the received signal, so that the detection direction of the received signal can be expressed in a conical form. 5 (B), a false detection direction MB having the same conical angle in the direction opposite to the actual detection direction RB is displayed as shown in FIG. 5 (B) in the line array sonar 100 This is called mirror phenomenon. The real detection bearing (RB) is called real bearing and the false detection bearing (MB) is called mirror bearing. In order to perform the target motion analysis on the characteristics of the linear array sonar 100, it is required to distinguish between the actual detection direction (RB) and the false detection direction (MB).

6 is a diagram showing the correlation between the detection azimuth, the arrival angle, and the actual target azimuth of the signal received in the line array sonar.

6, the correlation between the detection azimuth (? 3), the arrival angle (? 2), and the actual target azimuth (? 1) of the received signal in the line array sonar 100 can be expressed by a cosine function have.

[Equation 1]

In the actual line array sonar 100, the technique of estimating the target azimuth (? 1) using the detection azimuth (? 3) of the received signal is a very important process in accurate target motion analysis. In the target motion analysis, the detection orientation 3 can be obtained from the signal information received in the linear array sonar 100. Therefore, if the arrival angle of the signal [theta] 2 can be known, the target orientation [theta] 1 can be calculated through the above expression (1).

This arrival angle (θ2) can be calculated through Eigenray info. 7 is a table showing an example of Eigenray info of the Bellop model based on the sound line theory.

Since the path of the signals received in the line array sonar 100 depends on the distance between the line array sonar 100 and the target, the detection angle? 3 and the target azimuth angle? 1).

8 to 10 are graphs showing the accumulation of errors between the detection orientation and the target orientation using the arrival angles obtained from Eigenray info for each of the multipath signals. FIG. 8 is a graph showing the error between the detection orientation and the target orientation in the marine environment of Ulleung, North Korea, January 2000, where the distance between the sonar array and the target is 5 km and the sea floor depth is 2000 m. FIG. 9 is a graph showing the error between the detection orientation and the target orientation in the marine environment of Ulleung, Korea, January 2000 where the distance between the sonar array and the target is 15 km and the sea floor depth is 2000 m. FIG. 10 is a graph showing the error between the detection orientation and the target orientation in the marine environment of Ulleung, North Korea, where the distance between the sonar array and the target is 30 km and the sea floor depth is 2000 m. In the graph, the inverted triangles represent the signal with the diameter, the triangles represent the sea level reflection signal, and the square points represent the sea level reflection signal.

Referring to FIGS. 8 to 10, it can be seen that the diameter signal and the sea level reflection signal of the multipath signals exhibit almost the same error, and the error between the detection direction and the target direction is very small. Therefore, it is possible to perform almost accurate target motion analysis even if the target motion analysis using the existing straight line is performed using the diameter signal and the sea level reflection signal.

However, in the case of sea floor reflections, there is a large error between the detection direction and the target direction as compared with the signal with the diameter and the sea level reflection signal. In particular, the closer the distance from the target is, the larger the error is. Therefore, when performing the target motion analysis using the signal based on the existing straight line, there is a high possibility that many errors occur in the target motion analysis. Therefore, a technique to distinguish the reflections from the bottom of Eigenray info is required.

As described above, in order to perform the target motion analysis, it is necessary to distinguish between the real detection direction (RB) and the false detection direction (MB) due to the characteristics of the linear array sonar (100) Distinction needs to be made between the detection direction? 3 of the multipath signals S1, S2 and S3 and the bottom bottom reflection signal S1 having a large error in the target orientation? 1.

To this end, the target motion analyzing step S30 is a step of analyzing the detection direction? 3 of the signal received in the first signal receiving step S10 and the detection direction? 3 of the signal received in the second signal receiving step S20, , The detection direction in which the relative orientation change rate is relatively large is determined as the false detection direction (MB) in the section in which the linear array sonar (100) changes from the first movement route to the second movement route, This small detection azimuth is determined as the actual detection azimuth (RB).

The target motion analyzing step S30 compares the rate of change of the direction of the direction of the pointer in the actual detection direction RB in the section in which the line array sonar 100 changes and judges the changed signal as the bottom surface reflection signal S3 do. 11 is a graph illustrating accumulation and display of a detection direction of a received signal according to movement of a linear array sonar according to an embodiment of the present invention over time. 12 is a graph illustrating accumulation and display of detection signals of received signals according to movement of a linear array sonar according to a comparative example of the present invention over time.

11 and 12 show the movement path of the linear array sonar 100 and the movement path of the target 200. In FIG. The movement path R0 of the target 200 appears in the direction from the high latitude to the low latitude. 11, a transition R3 is generated from the first movement route R1 to the second movement route R2, whereas in FIG. 12, a straight line And moves to the path R4.

11 and 12 are graphs showing accumulation and display of the detection orientation? 3 of a signal received in the linear array sonar 100. In FIG. Four diagonal lines G1 to G4 are received in the graph by the multipath propagation phenomenon, and the actual detection orientation and the false detection orientation are displayed due to the characteristics of the linear array sonar 100. [ Through the graph, it can be seen that two different path signals among the multi-path signals are received, but it is difficult to distinguish which paths are being received.

11, two diagonal lines G2 and G4 among the four diagonal lines G1 to G4 receive a large influence (refer to area A) in the section R3 where the line array sonar 100 changes, The two diagonals G1 and G3 are relatively less affected. In the target motion analyzing step S30 according to the present invention, the two diagonal lines G1 and G3 which are relatively less influenced are determined as the actual detection direction RB and the two diagonal lines G2 and G4, It is judged to be a false detection direction (MB).

In the section R3 in which the line array sonar 100 changes, one of the two actual detection diagonal lines G1 and G3 is affected little while the other one G3 is relatively influenced. . In the target motion analysis step S30 according to the present invention, the actual dioptric line G1, which is relatively less influenced, is determined to be the signal S1 or the sea level surface reflected signal S2 by the diameter, and the diagonal line G3 ) As the bottom surface reflection signal S3.

12, when the line array sonar 100 does not turn, the four diagonal lines G1 to G3 displayed on the graph exhibit the same rate of change, and the actual detection direction RB and the false detection It is not easy to distinguish the bearing (MB) and the diagonal line by the bottom reflection signal (S3).

As described above, when the bottom surface reflection signal S3 is divided, the motion of the target 200 proceeds to the detection orientation? 3 of the signals. The motion analysis of the target 200 estimates the actual target orientation [theta] 1 of the target 200 through the detection orientation [theta] 3.

FIG. 13 is a graph showing a process of estimating the actual target orientation of the target through the actual detection orientation of the signal with the diameter and the sea level reflection signal, FIG. 14 is a graph showing the actual target orientation of the target through the actual detection orientation of the bottom- And FIG.

First, referring to FIG. 13, when applying the straight line L1, the actual detection orientation 3 of the signal S1 and the sea surface reflection signal S2 with the diameter is oriented in the same direction as the actual target orientation 1 of the target . Accordingly, when the diameter S1 is recognized as the signal S1 or the sea level surface reflection signal S2, the motion of the accurate target 200 can be analyzed by applying the straight line L1.

Referring to FIG. 14, when the straight line L1 is applied to the bottom surface reflection signal S3, it is known that a large error E is generated between the actual detection direction 3 and the actual target direction 1 of the target have. It is difficult to accurately analyze the motion of the target 200 by applying the straight line L1 when it is identified as the bottom surface reflection signal S3.

Due to such a problem, in the present invention, when it is identified as the bottom surface reflection signal S3, it provides a new method of estimating the default line.

In the target motion analysis step S30 according to the present invention, the underwater target 200 is located in a section between the detection orientation? 3 of the signal determined as the bottom surface reflection signal S3 and the line array sonar 100 The target area is set as the target area. Then, unit target orientations are set by dividing the target estimated area into a plurality of predetermined azimuth units, and an arrival angle [theta] 2 of the signals received in the line array sonar 100 is calculated for each unit target azimuth.

Ray-tracing is performed for each of the calculated arrival angles? 2 to calculate a distance at which the bottom floor reflection signal S3 reaches the expected depth of the underwater target 200, And display target points and linearize the display points to generate a target prediction diagonal line. The target expected diagonal line generated by this process appears as a curved diagonal line.

FIG. 15 is a diagram illustrating a method of generating a target prediction diagonal line according to an embodiment of the present invention, and FIG. 16 is a graph of analyzing a target motion with target target diagonal lines generated according to the method of FIG.

Referring to FIG. 15, the detection direction 3 of the bottom surface reflection signal S3 can be confirmed in real time by the value received in the linear array sonar 100. And the undersurface reflection signal S3 are received through bottom surface reflection, the arrival angle 2 reaching the line array sonar 100 has a value between 0 and 90 degrees. It can be seen that the actual target azimuth? 1 of the target 200 is located between the end-fire of the line array sonar 100 and the detection azimuth? 3 of the undersurface reflectance signal S3. Here, the section between the end of the line array sonar 100 and the detection direction 3 of the bottom surface reflection signal S3 is set as the target expected area T1 in which the underwater target can be located.

Then, the unit target orientations T2 are set by dividing the target expected zone T1 into a plurality of predetermined azimuth units, and the arrival of the signals received in the line array sonar 100 for each unit target azimuths T2 The angle? 2 is calculated. Here, the set orientation and the number of unit target orientations T2 are defined by the user. Ray-tracing is performed for each of the calculated arrival angles? 2 to calculate the distance at which the bottom seepage reflection signal S3 reaches the target expected water depth. The calculated distance is displayed for each unit target orientation T2 and the display points P1 are linearized to generate the target expected discretion line L2

Referring to FIG. 16, it can be seen that the target 200 is located on the target expected diagonal line L2 of the curve generated by the above process.

Therefore, when the detection azimuth? 3 is identified as the undersurface reflection signal S3, it can be seen that accurate target motion analysis is possible if the target expected diagonal line L2 of the curve, not the straight diagonal line, is applied.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

S10: Receiving the first signal
S20: receiving the second signal
S30: Target motion analysis step
100: Line array sonar
200: Underwater target
S1: Signal with a diameter
S2: sea level reflection signal
S3: Seabed reflection signal
θ1: Target bearing
θ2: reaching angle
θ3: detection bearing

Claims (6)

A first signal receiving step in which a line array sonar is traversed along a first movement path and receives a signal generated in an underwater target;
A second signal receiving step in which the line array sonar is traversed along a second movement path in a direction different from the first movement path and receives a signal generated in the underwater target; And
And a target motion analysis step of analyzing the motion of the underwater target from the signal received in the linear array sonar.
The method according to claim 1,
Wherein the detection orientation of the signal received in the linear array sonar includes an actual detection orientation and a false detection orientation,
Wherein the target motion analyzing step comprises:
The method comprising: accumulating a detection direction of a signal received in the first signal receiving step and a detection direction of a signal received in the second signal receiving step,
The detection direction having a relatively large rate of change is determined to be the false detection direction in a section in which the linear array sonar changes from the first movement path to the second movement path and the detection direction having a relatively low rate of change is set as the actual detection direction To-be-measured.
The method according to claim 1,
The signal received in the line array sonar includes a sea level reflection signal received after being reflected on the sea surface, a sea floor reflection signal received after being reflected on the sea floor, and a signal received with the diameter being reflected on the sea level or the sea floor In addition,
Wherein the target motion analyzing step comprises:
The actual detection orientation of the signal received in the first signal reception step and the actual detection orientation of the signal received in the second signal reception step are accumulated with time,
Wherein when the rate of change of the actual detection direction changes during the transition period in the section in which the line array sonar transitions from the first movement route to the second movement route as the bottom floor reflection signal, Way.
The method of claim 3,
The target motion analysis step
Setting a zone between the detection orientation of the signal determined as the bottom surface reflection signal and the line array sonar as a target area in which the underwater target can be located,
Setting the unit target orientations by dividing the target expected area into a plurality of predetermined azimuth units,
Calculates an arrival angle of a signal received in the linear array sonar for each of the unit target orientations,
Calculating a distance at which the bottom surface reflection signal reaches the expected water depth of the underwater target by performing line tracing for each of the calculated arrival angles,
Wherein the calculated distance is displayed for each unit target orientation and the display points are linearized to generate a target prediction diagonal line.
The method of claim 3,
Wherein the target expected diagonal line is generated as a curve.
A computer-readable recording medium on which a program for performing the method according to any one of claims 1 to 5 is recorded.

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