KR101117760B1 - 3-d ultrasonics revision method for submarine topography exploration - Google Patents

Abstract

PURPOSE: A three dimensional sound wave correction method is provided to accurately measure an arrival point of a sound wave by enabling a wave transmission and reception unit to emit the sound wave. CONSTITUTION: The three dimensional location and the attitude of a transmission and reception apparatus are determined through the position coordination of an observation platform(S1). A water depth layer is allocated to random numbers according to water depth. The water depth layer which lastly receives a sound wave transmitted by the determined transmission and reception apparatus(S2). A displacement value and a reflection point are calculated(S3).

Description

3-D ultrasonics revision method for submarine topography exploration

The present invention relates to a three-dimensional sound speed correction method for the exploration of the seabed topography, in particular, the point where the sound wave projected from the transceiver to reach the sea floor by using the sound wave is refracted according to the depth of the water, the sound speed varies depending on the depth of the water The present invention relates to a three-dimensional sound velocity correction method for underwater topography that can be measured accurately.

In general, in order to prepare a seabed topography, a wave receiver is installed on an observation platform, and the depth to the sea bottom is measured by measuring the time for the sound wave, for example, the ultrasonic wave, to return to the sea bottom. It is common to create a seabed topography by repeating this process.

However, the speed of sound waves is varied by changing the density, water temperature, etc. according to the depth of the seabed. In addition, a phenomenon in which sound waves are refracted occurs depending on the depth of the sea floor. As light passes through two media having different densities, sound waves are refracted according to the depth of the depth layer, as if refraction occurs at the interface.

Therefore, since the sound waves go straight and reach the sea bottom when the conventional seabed topography is created, the point where the actual sound waves reach the sea bottom is different from the actual state. Therefore, there is a need for a method of correcting sound velocity in order to create a more accurate seabed topography.

The present invention was conceived in consideration of the above-described matters, and reflects the phenomenon that the sound waves are deflected according to the depth of the water, so that it is possible to accurately calculate the point where the sound wave projected from the transceiver reaches the sea bottom. Its purpose is to provide a dimensional sound speed correction method.

A three-dimensional sound speed correction method according to the present invention for achieving the above object, the position and attitude determination step of determining the three-dimensional position of the transceiver using the position coordinates of the observation platform; A depth-depth determination step of dividing the depth layer by an arbitrary number according to the depth of the depth, and calculating a final depth layer in consideration of refraction of sound waves projected from the positioned transceivers through each of the depth layers; And a displacement value calculating step of calculating a displacement value between an imaginary line extending vertically from the transceiver to the sea bottom and a point where the sound wave is reflected from the sea bottom in the depth layer where the sound wave finally reached. It is done.

In addition, the depth-determination step of determining, the initial incident angle calculation step of determining the angle of incidence that the sound waves projected from the positional transceivers into the first depth layer; A depth-of-depth incident angle determining step of calculating a layer incident angle in each depth layer after the initial depth layer using a sound velocity profile providing the sound velocity according to each of the divided depth layers and the initial incident angle; Depth-based distance calculation step of calculating the distance traveled by the sound waves in the first depth layer and each depth layer existing below the first depth layer by using the initial incident angle and the layer-by-layer incident angle; An elapsed time calculating step of calculating an elapsed time of the sound wave required to pass through each depth layer by using the traveling distance of the sound waves calculated in the distance calculation step for each depth layer and the sound velocity in each depth layer; The final depth of the layer at which the sound wave reaches is determined by comparing the 1/2 value of the time when the sound wave is reflected back to the sea bottom and the cumulative elapsed time of accumulating the elapsed time at each depth layer calculated in the elapsed time calculating step. It is preferable to include; sonic wave depth depth determination step.

In addition, the sound wave reaching depth layer determining step, the first cumulative elapsed time required when the sound wave proceeds to the N-1th depth layer, and the second cumulative elapsed time required when the sound wave proceeds to the Nth depth layer; Compared with the 1/2 value, when the 1/2 value exists between the first and second cumulative elapsed times, the sound waves may include a cumulative elapsed time comparison step of determining that the sound waves have reached the N layer. .

The displacement value calculating step may include: an initial incident angle calculation step of determining an incident angle at which the sound waves projected from the positioned transceivers enter the first depth layer; A depth-of-depth incident angle determining step of calculating a layer incident angle in each depth layer after the initial depth layer using a sound velocity profile providing the sound velocity according to each of the divided depth layers and the initial incident angle; It is preferable to include a displacement accumulation step of calculating and accumulating a displacement value moved in a vertical direction from the imaginary line for each depth layer by using the initial incident angle and the incident angle of each floor and the depth of each depth layer.

In addition, the displacement value calculating step, the displacement moved in the vertical direction from the imaginary line for each depth layer by using the initial incident angle and the incident angle of each floor, and the traveling distance of the sound waves for each depth layer calculated in the distance calculation step for each depth layer. It is preferable to include a displacement accumulation step of calculating and accumulating a value.

The displacement accumulation step may include a first displacement accumulation step and an Nth depth layer that accumulate displacement values to an N-1th depth layer when the depth layer reached by the sound wave in the determining depth reaches the Nth layer. And a second displacement accumulation step of calculating a residual displacement value at, wherein the residual displacement value of the second displacement accumulation step is the sound wave at a value of 1/2 of the time when the sound wave is reflected by the sea bottom and returns. A remaining time calculating step of calculating a remaining time by subtracting a first cumulative elapsed time required when the N-1th layer proceeds to the N-1th layer; A remaining distance calculating step of calculating a traveling distance of the sound wave during the remaining time in the Nth layer; And a residual displacement calculation step of calculating a residual displacement value of the sound wave moved in the vertical direction from the imaginary line in the Nth depth layer by using the residual distance and the incident angle in the Nth layer. .

In addition, in the step of determining the position and attitude of the transmitter, it is preferable to consider yawing, pitching, and rolling of the observation platform.

In addition, it is preferable to further include a sea surface coordinate calculation step of calculating the coordinates of the sea surface using the displacement value and the position of the transceiver.

The three-dimensional sound velocity correction method for exploration of the seabed terrain according to the present invention considers that the sound waves are refracted according to the depth of the water, and thus provides the effect of accurately calculating the point where the actual sound waves reach the sea floor.

1 is a block diagram of a sound speed correction method according to an embodiment of the present invention;
2 is a diagram schematically illustrating a process of three-dimensionally determining a position and a posture of a transceiver;
3 is a diagram schematically showing a path of sound waves according to water depth;
4 is a diagram illustrating an essential part of FIG. 3;

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a sound speed correction method according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram schematically illustrating a process of three-dimensionally determining a position and a posture of a transceiver. FIG. 3 is a view schematically showing a path of sound waves depending on the depth, and FIG. 4 is a view illustrating main parts of FIG. 3.

First, referring to Figures 1 and 2, the three-dimensional sound speed correction method for the seabed terrain exploration according to an embodiment of the present invention, the position and attitude determination step (S1), reach depth layer determination step (S2), and displacement value A calculation step S3 is included.

The transceiver position and attitude determination step (S1) is a step of determining the three-dimensional position and attitude of the transceiver using the position coordinates of the observation platform (10). At this time, considering the yawing, pitching, and rolling of the observation platform 10, the position and attitude of the transceiver 20 are determined in three dimensions. That is, the three-dimensional position and attitude of the transceiver 20 is determined first of the three-dimensional position and attitude of the observation platform 10, the combination of the relative position of the transceiver 20 with respect to the observation platform 10 20) determine the three-dimensional position and posture. The transceiver 20 is coupled to the observation platform 10 to project sound waves toward the sea bottom 30. As the sound wave, an ultrasonic wave or the like is used.

The reaching depth layer determining step S2 divides the depth layer by an arbitrary number according to the depth of the depth, and finally considers that the sound waves projected from the positioned transceiver 20 are refracted when passing through each depth layer. It is a step of determining the depth of water. In this case, it is assumed that the sound waves go straight in each depth layer.

As shown in Figures 3 and 4, the sound waves are shown to go straight in each depth layer. When the sound wave is incident at the angle of β1 in the first depth layer, if no refraction is made in each depth layer, the sound wave will proceed to the ideal path B2, but the actual sound wave will be refracted in each depth layer and proceed along the actual path B1.

That is, a sound velocity profile obtained by dividing the depth layer by an arbitrary number according to the depth of the water is prepared in advance, and the sound waves projected from the transceiver 20 pass through each depth layer in advance in consideration of the density, the water temperature, etc. of the depth layer. Considering proceeding at the determined sound velocity. That is, the sound waves are refracted in each depth layer and proceed at different sound speeds according to the respective depth layers.

The depth determination step includes determining an initial incident angle (S21), determining an incident angle for each depth layer (S22), calculating a distance for each depth layer (S23), calculating an elapsed time (S24), and determining an acoustic wave depth layer (S25). Include.

Referring to FIG. 2, in the initial incident angle determining step S21, after determining the position and attitude of the transceiver 20 in three dimensions, the incident angle β1 at which the sound wave projected from the transceiver 20 enters the first depth layer is determined. It's a step.

The position and attitude of the transmitter 20 vary with the yawing, rolling, and pitching of the observation platform 10, and the initial incident angle (β1) of the sound wave projected to the sea floor according to the position and attitude of the transmitter 20 determined in consideration of this. This is different.

As shown in Fig. 2, when the wave receiver 20 projects sound waves to the first depth layer, the angle of inclination with respect to the imaginary line L extending vertically from the wave receiver 20 toward the sea bottom 30 is Initial incidence angle β1.

The determining the incident angle for each depth layer (S22) is a step of calculating the incident angles (β2, ... βn-1, βn) for each depth layer. The sound velocity profile provides the sound velocity in each of the divided depth layers, and since the initial initial incidence angle β1 is known, the incident angle β2 of the next depth layer next to the initial depth layer is calculated using Snell's law. By repeating this process, the incident angles (β2, ... βn-1, βn) in each depth layer after the initial depth layer are continuously calculated.

The distance calculation step (S23) for each depth layer is a step of calculating a travel distance actually progressed by the sound waves in each depth layer. Using the initial incident angle β1 and the layer incident angle β2,..., N-1, βn, the distance traveled by the sound waves in the initial depth layer and each depth layer existing below the initial depth layer is calculated.

Specifically, since the traveling distance Δr1 of the sound waves in the first depth layer (first depth layer) knows the initial incident angle β1 and the depth Δz1 of the initial depth layer in the sound velocity profile, the traveling distance is the depth of the initial depth layer Δz1. It can be calculated by dividing by cos (β1).

The advancing distance Δr2 of sound waves in the depth layer next to the first depth layer (hereinafter referred to as “second depth layer”) may be calculated by dividing the depth Δz2 of the second depth layer by cos (β2). By repeating the above process, the distances (Δr1, Δr2, ... Δrn-1, Δrn) in which sound waves travel in each depth layer are respectively calculated.

The elapsed time calculating step (S24) is a step of calculating the elapsed time of the sound wave required when the sound wave passes through each depth layer. The elapsed time is calculated using the traveling distances Δr 1, Δr 2,... Δrn-1, Δrn of the sound waves calculated in the distance calculation step S23 for each depth layer, and the sound velocity in each of the depth layers.

That is, since the sound velocity in each depth layer is provided in the sound velocity profile, and in the distance calculation step S23 for each depth layer, the travel distances Δr1, Δr2, ... Δrn-1, Δrn in each depth layer are calculated. The elapsed time of sound waves in each depth layer can be calculated.

The sound wave reaching depth layer determining step (S25) is a step of determining the final depth layer that the sound waves finally reached from the depth layer divided according to the depth of the water.

When the sound wave reaches the cumulative elapsed time of accumulating the elapsed time in each depth layer calculated in the elapsed time calculating step (S24) and the 1/2 value of the time when the sound wave is reflected on the bottom surface 30 and returns. Determine the final depth.

The sound wave reaching depth layer determination step S25 includes a cumulative elapsed time comparison step S251.

Specifically, the cumulative elapsed time comparison step (S251), the first cumulative elapsed time required when the sound wave proceeds to the N-1th depth layer, and the second cumulative time required when the sound wave proceeds to the Nth depth layer The elapsed time is compared with the 1/2 value above. When the 1/2 value is present between the first and second cumulative elapsed times, the sound wave reaches the N layer.

Here, the first cumulative elapsed time means the cumulative elapsed time until the sound wave enters the Nth depth layer, and the second cumulative elapsed time is the cumulative elapsed time until the sound wave enters the N + 1th depth layer. Means.

Therefore, the 1/2 value is less than the second cumulative elapsed time means that the sound wave has reached somewhere in the Nth depth layer.

Through this process, the depth layer at which the sound wave finally reaches is determined in consideration of the refractive index of the sound wave according to the depth of the water.

The displacement value calculating step S3 is a step of calculating a displacement value with a point where the sound wave is reflected from the bottom surface 30 in the depth layer where the sound wave finally reached. That is, it is a step of calculating the displacement value between the virtual line L which extends perpendicularly from the wave receiver 20 toward the sea bottom 30 and the point where the sound wave finally reaches the sea bottom 30.

The displacement value calculating step S3 includes an initial incident angle calculating step S31, a depth-deciding incident angle determining step S32, and a displacement accumulation step S33.

The initial incident angle calculating step S31 and the depth-of-depth incident angle determining step S32 employ the method used in the reaching depth layer determining step S2.

In the displacement accumulation step S33, the initial incident angle β1 and the layer incident angle β2,... Βn-1.βn and the depths of the depth layers Δz1, Δz2,... Δzn-1, Δzn The displacement values moved in the vertical direction from the imaginary line L for each depth layer are calculated and accumulated.

3 and 4, the displacement value ΔV1 at the first depth layer is calculated using the initial incident angle β1 and the depth Δz1 of the first depth layer. In other words, multiplying tan (β1) by the depth Δz1 of the first depth layer yields the displacement value ΔV1 in the first depth layer.

Subsequently, the displacement value ΔV2 in the second depth layer that exists immediately below the first depth layer is calculated by multiplying tan (β2) by the depth Δz2 of the second depth layer.

By repeating this process, the displacement values (ΔV1, ΔV2, .., ΔVn-1, ΔVn) in each depth layer are calculated, and when accumulated, from the imaginary line L extending the transceiver 20 vertically downward. The displacement value in the horizontal direction with the point of the sea bottom 30 where the sound wave finally reached is calculated.

At this time, in order to accumulate displacement values in the displacement value calculating step S3, the traveling distances of the sound waves for each depth layer calculated in the distance calculation step S23 for each depth layer Δr1, Δr2, ... Δrn-1, Δrn The displacement value can be calculated using. That is, the displacement value may be calculated by multiplying the advancing distances Δr 1, Δr 2,..., Δrn-1, Δrn of sound waves for each depth layer by the cosine of the incident angle in each depth layer.

Using the initial incident angle β1 and the traveling distance Δr1 of the sound wave in the initial depth layer, the displacement value ΔV1 in the initial depth layer is calculated. In other words, multiplying the traveling distance Δr1 of sound waves in the first depth layer by cos (β1) yields the displacement value ΔV1 in the first depth layer.

Next, the displacement value (DELTA) V2 in the 2nd depth layer which exists just under the initial depth layer is computed by multiplying the traveling distance of the sound wave in a 2nd depth layer by cos ((beta) 2).

By repeating this process, the displacement values (ΔV1, ΔV2, .., ΔVn-1, ΔVn) in each depth layer are calculated, and when accumulated, from the imaginary line L extending the transceiver 20 vertically downward. The displacement value in the horizontal direction with the point of the sea bottom 30 where the sound wave finally reached is calculated.

In addition, in the sound speed correction method according to the present embodiment, the displacement accumulation step S33 includes a first displacement accumulation step S331 and a second displacement accumulation step S332.

The first displacement accumulation step S331 is a step of accumulating displacement values to the N-1 th depth layer when the depth layer reached by the sound wave in the determination of the depth reach layer S2 is the Nth layer.

The second displacement accumulation step (S332) is a step of calculating a residual displacement value in the Nth depth layer in which the acoustic wave finally reached. The second displacement accumulation step S332 includes a residual time calculation step S3321, a residual distance calculation step S3322, and a residual displacement calculation step S3323 to calculate the residual displacement value.

The remaining time calculating step (S3321) is a first cumulative elapsed time required when the sound wave proceeds to the N-1 th layer at a value 1/2 of the time when the sound wave is reflected by the sea bottom 30 and returns. The remaining time is calculated by subtracting. That is, when the sound wave finally reaches the Nth depth layer, the sound wave may be located somewhere in the Nth depth layer. In other words, somewhere in the Nth depth layer becomes the point where the sea bottom 30 is located.

The remaining distance calculating step (S3322) is a step of calculating a traveling distance in which the sound wave proceeds for the remaining time in the Nth layer. The remaining distance is calculated by multiplying the sound speed in the Nth depth layer by the remaining time.

The residual displacement calculation step (S3323), the residual displacement in which the sound wave is moved in the vertical direction from the imaginary line L in the Nth depth layer by using the residual distance and the incident angle βn in the Nth layer. Compute the value.

As a result, the displacement value in which the sound wave projected from the transceiver 20 moves horizontally with respect to the imaginary line L extending vertically downward from the transceiver 20 is accumulated in the first displacement accumulation step S331. It is given by adding up the displacement value and the residual displacement value calculated in the second displacement accumulation step S332.

As described above, the three-dimensional sound speed correction method for seabed terrain exploration according to the present invention utilizes the property that the speed of sound is refracted according to the depth of the water. That is, by dividing the depth layer, a sound velocity profile having a depth and sound velocity set in advance for each depth layer is provided, and the position of the transceiver 20 is determined three-dimensionally, and the initial incident angle of the sound wave projected from the transmitter 20 to the sea floor is projected. And the incident angle for each layer. Finally, the depth of the sound wave reached and the displacement value in the depth of the sea layer are calculated to accurately calculate the position of the bottom surface 30 on which the sound wave reaches.

On the other hand, the three-dimensional sound speed correction method for the seabed terrain exploration according to an embodiment of the present invention, further comprises a seabed surface coordinate calculation step (S4).

The sea surface coordinate calculation step (S4) calculates the coordinates of the sea surface by using the displacement value calculated in the displacement value calculating step (S3) and the three-dimensional position of the transceiver 20. The transmitter 20 calculates the point where each sound wave reaches the sea bottom 30 individually while projecting a plurality of sound waves through the sea bottom, and combines them to calculate the coordinates of the sea bottom surface. Since the three-dimensional coordinates of the transceiver 20 are determined and the displacement value based on the transceiver 20 is calculated, the combination of these implements the absolute coordinates of the sea surface.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and many other modifications can be provided without departing from the scope of the present invention.

10 ... Observation Platform 20 ... Water Transceiver
30 ... bottom

Claims (8)

A transmitter position and attitude determination step of determining a three-dimensional position and attitude of the transmitter using position coordinates of the observation platform;
A depth-depth determination step of dividing a depth layer by an arbitrary number according to the depth of the depth, and calculating a final depth layer in consideration of refraction of sound waves projected from the positioned transceivers through each of the depth layers;
And a displacement value calculating step of calculating a displacement value between an imaginary line extending vertically from the transceiver to the sea bottom and a point where the sound wave is reflected from the sea bottom in the depth layer where the sound wave finally reached. 3D Sonic Wave Compensation Method for Seabed Terrain Exploration. The method of claim 1,
The depth reach determination step,
An initial incident angle calculating step of determining an incident angle at which the sound waves projected from the positioned transceivers enter the first depth layer;
A depth-of-depth incident angle determining step of calculating a layer incident angle in each depth layer after the initial depth layer using a sound velocity profile providing the sound velocity according to each of the divided depth layers and the initial incident angle;
Depth-based distance calculation step of calculating the distance traveled by the sound waves in the first depth layer and each depth layer existing below the first depth layer by using the initial incident angle and the layer-by-layer incident angle;
An elapsed time calculating step of calculating an elapsed time of the sound wave required to pass through each depth layer by using the traveling distance of the sound waves calculated in the distance calculation step for each depth layer and the sound velocity in each depth layer;
The final depth of the layer at which the sound wave reaches is determined by comparing the 1/2 value of the time when the sound wave is reflected back to the sea bottom and the cumulative elapsed time of accumulating the elapsed time at each depth layer calculated in the elapsed time calculating step. A three-dimensional sound speed correction method for submarine topography, characterized in that it comprises a; The method of claim 2,
The sound wave reaching depth layer determining step may include a first cumulative elapsed time required when the sound wave proceeds to the N-th depth layer and a second cumulative elapsed time required when the sound wave proceeds to the Nth depth layer. Compared with the value of 2, when the 1/2 value is present between the first and second cumulative elapsed time, the sound wave comprises a cumulative elapsed time comparison step of determining that the arrival to the N layer 3D Sound Compensation Method for Terrain Exploration. The method of claim 1,
The displacement value calculating step,
An initial incident angle calculating step of determining an incident angle at which the sound waves projected from the positioned transceivers enter the first depth layer;
A depth-of-depth incident angle determining step of calculating a layer incident angle in each depth layer after the initial depth layer using a sound velocity profile providing the sound velocity according to each of the divided depth layers and the initial incident angle;
And a displacement accumulation step of accumulating and accumulating a displacement value moved in the vertical direction from the imaginary line for each depth layer by using the initial incident angle and the incident angle of each floor and the depth of each depth layer. 3D Sound Compensation Method. The method of claim 2,
The displacement value calculating step,
A displacement accumulation step of calculating and accumulating displacement values moved in the vertical direction from the imaginary line for each depth layer by using the initial incident angle and the incident angle of each floor and the traveling distance of sound waves for each depth layer calculated in the distance calculation step for each depth layer. Three-dimensional sound speed correction method for submarine topography, characterized in that it comprises a. The method of claim 4, wherein
The displacement accumulation step,
Computing the first displacement accumulation step of accumulating the displacement value to the N-1th depth layer and the residual displacement value in the Nth depth layer when the depth layer reached by the sound wave in the step of determining the depth reaches the N-th layer; A second displacement accumulation step,
The residual displacement value of the second displacement accumulation step is
A remaining time calculating step of calculating a remaining time by subtracting a first cumulative elapsed time required when the sound wave proceeds to the N-1 th layer from a 1/2 value of the time when the sound wave is reflected by the sea bottom and returns;
A remaining distance calculating step of calculating a traveling distance of the sound wave during the remaining time in the Nth layer;
And a residual displacement calculation step of calculating a residual displacement value of the sound wave moved in the vertical direction from the imaginary line in the Nth depth layer by using the residual distance and the incident angle in the Nth layer. 3D Sonic Wave Compensation Method for Seabed Terrain Exploration The method of claim 1,
In the step of determining the position and attitude of the transmitter, the three-dimensional sound speed correction method for subsea landform exploration, characterized in that yawing, pitching, rolling of the observation platform. The method of claim 1,
And calculating a subsurface surface coordinate using the displacement value and the position of the wave receiver.

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