CN110412588A - A method and system for measuring three-dimensional information of a target based on a cross array - Google Patents

Abstract

The invention discloses a method and system for measuring three-dimensional information of a target based on a cross-array. The method includes: respectively performing dynamic focusing beamforming on the echo data in the element domain of the receiving array to form a horizontal-distance two-dimensional acoustic map and Vertical-distance two-dimensional acoustic image; use the signal amplitude and target model to jointly detect the horizontal-distance two-dimensional acoustic image to obtain target horizontal information; integrate target horizontal information in the vertical-distance two-dimensional acoustic image, and use the energy center Combined detection with dynamic threshold to estimate the vertical information of multiple suspected target points; use dynamic threshold detection for multiple suspected target points to eliminate non-suspect points to obtain target points; combine the pitch angle and structure of the cross array to estimate the seabed The distribution of the sea surface, and then estimate the depth of the target; combine the depth of the target with the horizontal information of the target to obtain the three-dimensional information of the target. The method of the invention improves the adaptability and accuracy of target depth measurement, has small calculation amount and is easy to realize.

Description

A method and system for measuring three-dimensional information of a target based on a cross array

technical field

The invention relates to an underwater acoustic signal processing method in the marine field, in particular to a method and system for measuring three-dimensional information of a target based on a cross array.

Background technique

Image sonar can provide real-time underwater images for underwater navigation, underwater target search, hydraulic engineering monitoring and other application fields to realize underwater target detection. In practical engineering applications, the commonly used image sonar is two-dimensional image sonar. For forward-looking sonar, only the distance information and horizontal orientation information of the target can be obtained. In the process of target detection and recognition, in order to further confirm the target, in order to hunt or avoid the target, it is necessary to estimate the depth information of the target in the water. Three-dimensional imaging sonar can be used for underwater detection, and three-dimensional image information covering targets in waters can be obtained, that is, distance information, horizontal orientation information and depth information, but the hardware complexity of three-dimensional image sonar is high, and target detection is difficult increase.

Existing echo sounders, such as single-beam echo sounders and multi-beam echo sounders, mainly function to measure the depth of the seabed/lake bottom, and have poor performance in detecting and sounding small targets in water.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned technical defects, design a cross array, and propose a target three-dimensional information measurement method and system based on the cross array.

In order to achieve the above object, the present invention proposes a method for measuring three-dimensional information of a target based on a cross array, which is realized based on a cross array, and the cross array includes: a receiving array and a transmitting array, and the receiving array includes a horizontal The receiving base array and the vertical receiving base array share a transmitting base array; the method includes:

Perform dynamic focusing beamforming on the element field echo data of the receiving array to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image;

Using the signal amplitude and the target model to jointly detect the horizontal-distance two-dimensional acoustic image, and obtain the horizontal direction information of the target;

The horizontal information of the target is fused in the vertical-distance two-dimensional acoustic image, and the joint detection of the energy center and the dynamic threshold is used to estimate the vertical information of multiple suspected target points; the dynamic threshold detection is used for multiple suspected target points, and the non-suspected points are eliminated. Points, get the target points;

Combined with the pitch angle and structure of the cross array, the sea surface distribution of the seabed is estimated, and then the depth of the target is estimated;

Combining the depth of the target with the horizontal information of the target, the three-dimensional information of the target is obtained.

As an improvement of the above method, the dynamic focus beamforming is performed on the element field echo data of the receiving array to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image; specifically:

The number of array elements of the horizontal receiving array is M _h , a linear uniform array, and the distance between adjacent array elements is d _h , the number of array elements of the vertical receiving array is M _v , a linear uniform array, and the adjacent array elements The spacing is d _v , the received echo signals are x _h (t) and x _v (t) respectively, and the dynamic focusing reception pre-forming multi-beam forming is performed:

in, and are the weighted vectors of the horizontal receiving matrix and the vertical receiving matrix, respectively, θ _i represents the multi-beam pointing angle, the angle range is [θ _min ,θ _max ], θ _min is the minimum angle, θ _max is the maximum angle, and They are horizontal-distance acoustic image data and vertical-distance acoustic image data respectively, forming a two-dimensional image.

As an improvement of the above method, the joint detection of the horizontal-distance two-dimensional acoustic image by using the signal amplitude and the target model to obtain the target horizontal direction information specifically includes:

Calculate the echo signal strength EL ₀ of the target:

EL ₀ ＝SL ₀ -TL ₀ (R ₀ )+TS ₀

Among them, SL ₀ is the sound source level of the transmitting array; TS ₀ is the target strength of the detection target, the distance between the target and the cross array is R ₀ , and TL ₀ (R ₀ ) is the propagation loss related to the distance of the target point;

Calculate the target echo signal voltage V ₀ according to the receiving sensitivity of the horizontal receiving array:

V ₀ =10^((S _h +20logP _a )/20)

Among them, S _h represents the receiving sensitivity of the horizontal receiving matrix, and _Pa is the sound pressure corresponding to the received signal EL ₀ ;

According to the gain amplification of the receiving circuit system and the gain of beamforming, the signal amplitude A ₀ from the target in the beam domain is estimated;

The signal amplitude A ₀ is used as the detection threshold, combined with the target model pixel number N ₀ , the dynamic threshold detection of the horizontal array target is realized, and the horizontal distance position of the target is estimated and horizontal angle information

As an improvement of the above method, the horizontal information of the target is fused in the vertical-distance two-dimensional acoustic map, and the joint detection of the energy center and the dynamic threshold is used to estimate the vertical information of multiple suspected target points; The target point adopts dynamic threshold detection, removes non-suspect points, and obtains the target point; specifically includes:

in the area In, r ₀ is the distance set according to the test application scene, according to the received signal type and the transmitted pulse width, the calculated distance-to-time resolution is τ;

Select the energy estimation interval T _d , T _d =4τ, use the energy estimation interval T _d to divide the distance interval Divided into K energy intervals, the energy of each interval is expressed as

Among them, t _j is the starting moment of the jth energy interval, is the amplitude value of the j-th energy interval of the i-th beam vertically;

Sort the energy values of the K intervals, and obtain the kth energy concentration interval corresponding to the energy maximum value E _max as [t _k ,t _k +T _d ];

Calculate the average value of the data amplitude in the interval [t _k ,t _k +T _d ] for dynamic threshold detection, eliminate non-target points in the energy interval, and finally use the amplitude-time weighting method to estimate the scattering back of multiple beam targets. Arrival time of wave Arrival instant t _{a_m} :

Among them, N _b is the number of horizontal receiving beams; thus, the time value t _{a_m} and the corresponding amplitude value of the suspected target on each beam are estimated;

The dynamic threshold detection is performed on the suspected target points of multiple beams, and the targets with the number of beams larger than this threshold and the number of beams smaller than this threshold are regarded as non-suspect target points, and N _s suspected targets are obtained after eliminating non-suspect target points, and the estimated The arrival time values of N _s suspected target echoes and the corresponding beam angles, and the target point curve is drawn in the vertical-range acoustic map.

As an improvement of the above method, the combination of the pitch angle and structure of the cross array is used to estimate the distribution of the seabed and sea surface, and then estimate the depth of the target, specifically including:

Convert vertical-distance to rectangular acoustic map data into fan-shaped acoustic map display data:

Among them, rr _v is the distance information in the fan-shaped acoustic map, C is the underwater sound velocity, T _j is the sound wave propagation time, θ _{u, v} is the angle information in the fan-shaped image, x _u is the vertical-distance rectangular acoustic map Abscissa; u, v are positive integers;

The depth coordinate x _m0 of the sea surface in the sector diagram and the depth coordinate x _d0 of the bottom in the sector diagram are respectively:

Among them, H _m is the depth of the cross array from the sea surface; H _d is the depth of the cross array from the sea bottom, and the pitch angle of the cross array is φ _min and φ _max are the minimum and maximum angles of the vertical sector graph, respectively;

The arrival time values of N _s suspected target echoes and the corresponding beam angles are converted into the depth in the fan diagram as

According to the following judgment conditions

x _m0 < x _si < x _d0 , i=1,2,3,...,N _s

Further exclude suspected targets outside the sea surface and seabed;

For the screened suspected targets, perform dynamic threshold detection, estimate the vertical distance and angle (r _s0 , φ _s0 ) corresponding to the point with the maximum amplitude, and obtain the depth information of the target according to the triangular geometric relationship of the cross array for:

As an improvement of the above method, after estimating the depth of the target, it also includes: a step of correcting the depth of the target by using sound ray bending:

According to the information distance and angle (rs _s0 , φ _s0 ) in the vertical direction of the target, combined with the sound velocity profile, the depth direction is uniformly layered, and the depth is divided into N _H layers, and the depth of each layer is ΔH;

Compute the propagation time for each layer:

Δt _l = ΔH/c _l

Among them, c _l represents the sound velocity corresponding to the lth gradient layer; 1≤l≤N _H

Then the accumulative time t _z of the propagation time of each layer is:

When t _z ≥ 2r _s0 /C, the number of layers of the corresponding gradient layer is solved to be n _s ;

Then the corrected target depth for:

Indicates the sound velocity corresponding to the n _s gradient layer, is the final estimated depth of the target in the water.

As an improvement of the above method, the depth of the target is combined with the horizontal information of the target to obtain the three-dimensional information of the target, specifically:

Take the cross array as the body, establish a body coordinate system, the origin is at the intersection of the horizontal matrix and the vertical matrix, the horizontal matrix is to the right as the x direction, the vertical matrix is downward as the z direction, and the y direction is determined according to the right-hand rule;

Then in this coordinate system, the three-dimensional position of the target is:

The present invention also proposes a cross-array-based target three-dimensional information measurement system, the system comprising:

A cross array, the cross array includes: a receiving array and a transmitting array, the receiving array includes a horizontal receiving array and a vertical receiving array, both of which share a transmitting array;

The two-dimensional multi-beam image generation module is used to perform dynamic focusing beamforming on the array element domain echo data of the receiving array to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image;

The target level information estimation module is used to jointly detect the level-distance two-dimensional acoustic image by using the signal amplitude and the target model to obtain target level information;

The vertical target point detection module is used to fuse the horizontal information of the target in the vertical-distance two-dimensional acoustic map, and use the energy center and dynamic threshold joint detection to estimate the vertical information of multiple suspected target points; for multiple suspected targets Points adopt dynamic threshold detection to eliminate non-suspect points and obtain target points;

The depth information estimation module is used to combine the pitch angle and structure of the cross array to estimate the distribution of the seabed and sea surface, and then estimate the depth of the target;

The target three-dimensional information calculation module is used to combine the corrected target depth with the target horizontal direction information to obtain target three-dimensional information.

As an improvement of the above system, the specific implementation process of the two-dimensional multi-beam image generation module is as follows:

The number of array elements of the horizontal receiving array is M _h , a linear uniform array, and the distance between adjacent array elements is d _h , the number of array elements of the vertical receiving array is M _v , a linear uniform array, and the adjacent array elements The spacing is d _v , the received echo signals are x _h (t) and x _v (t) respectively, and the dynamic focusing reception pre-forming multi-beam forming is performed:

in, and are the weighted vectors of the horizontal receiving matrix and the vertical receiving matrix, respectively, θ _i represents the multi-beam pointing angle, the angle range is [θ _min ,θ _max ], θ _min is the minimum angle, θ _max is the maximum angle, and They are horizontal-distance acoustic image data and vertical-distance acoustic image data respectively, forming a two-dimensional image.

As an improvement of the above system, the specific implementation process of the target level information estimation module is as follows:

Calculate the echo signal strength EL ₀ of the target:

EL ₀ ＝SL ₀ -TL ₀ (R ₀ )+TS ₀

Among them, SL ₀ is the sound source level of the transmitting array; TS ₀ is the target strength of the detection target, the distance between the target and the cross array is R ₀ , and TL ₀ (R ₀ ) is the propagation loss related to the distance of the target point;

Calculate the target echo signal voltage V ₀ according to the receiving sensitivity of the horizontal receiving array:

V ₀ =10^((S _h +20logP _a )/20)

Among them, S _h represents the receiving sensitivity of the horizontal receiving matrix, and _Pa is the sound pressure corresponding to the received signal EL ₀ ;

According to the gain amplification of the receiving circuit system and the gain of beamforming, the signal amplitude A ₀ from the target in the beam domain is estimated;

The signal amplitude A ₀ is used as the detection threshold, combined with the target model pixel number N ₀ , the dynamic threshold detection of the horizontal array target is realized, and the horizontal distance position of the target is estimated and horizontal angle information

As an improvement of the above system, the vertical target point detection module includes: a vertical suspected target detection sub-module and a dynamic detection sub-module,

The vertical suspected target detection submodule is used to detect the suspected target on each beam in the vertical direction; specifically:

in the area In, r ₀ is the distance set according to the test application scene, according to the received signal type and the transmitted pulse width, the calculated distance-to-time resolution is τ;

Select the energy estimation interval T _d , T _d =4τ, use the energy estimation interval T _d to divide the distance interval Divided into K energy intervals, the energy of each interval is expressed as

Among them, t _j is the starting moment of the jth energy interval, is the amplitude value of the j-th energy interval of the i-th beam vertically;

Sort the energy values of the K intervals, and obtain the kth energy concentration interval corresponding to the energy maximum value E _max as [t _k ,t _k +T _d ];

Calculate the average value of the data amplitude in the interval [t _k ,t _k +T _d ] for dynamic threshold detection, eliminate non-target points in the energy interval, and finally use the amplitude-time weighting method to estimate the scattering back of multiple beam targets. Arrival time of wave Arrival instant t _{a_m} :

Among them, N _b is the number of horizontal receiving beams; thus, the time value t _{a_m} and the corresponding amplitude value of the suspected target on each beam are estimated;

The dynamic detection sub-module is used to perform dynamic threshold detection on the suspected target points of multiple beams, and the targets with the number of beams greater than the threshold and the number of beams smaller than the threshold are regarded as non-suspect target points, and after removing the non-suspect target points Get N _s suspected targets, estimate the arrival time values and corresponding beam angles of N _s suspected target echoes, and draw the target point curve in the vertical-range acoustic map.

As an improvement of the above system, the specific implementation process of the depth information estimation module is as follows:

Convert vertical-distance to rectangular acoustic map data into fan-shaped acoustic map display data:

Among them, rr _v is the distance information in the fan-shaped acoustic map, C is the underwater sound velocity, T _j is the sound wave propagation time, θ _{u, v} is the angle information in the fan-shaped image, x _u is the vertical-distance rectangular acoustic map Abscissa; u, v are positive integers;

The depth coordinate x _m0 of the sea surface in the sector diagram and the depth coordinate x _d0 of the bottom in the sector diagram are respectively:

Among them, H _m is the depth of the cross array from the sea surface; H _d is the depth of the cross array from the sea bottom, and the pitch angle of the cross array is φ _min and φ _max are the minimum and maximum angles of the vertical sector graph, respectively;

The arrival time values of N _s suspected target echoes and the corresponding beam angles are converted into the depth in the fan diagram as

According to the following judgment conditions

x _m0 < x _si < x _d0 , i=1,2,3,...,N _s

Further exclude suspected targets outside the sea surface and seabed;

For the screened suspected targets, perform dynamic threshold detection, estimate the vertical distance and angle (r _s0 , φ _s0 ) corresponding to the point with the maximum amplitude, and obtain the depth information of the target according to the triangular geometric relationship of the cross array for:

As an improvement of the above system, the system also includes a depth information estimation module, and the specific implementation process is as follows:

According to the information distance and angle (rs _s0 , φ _s0 ) in the vertical direction of the target, combined with the sound velocity profile, the depth direction is uniformly layered, and the depth is divided into N _H layers, and the depth of each layer is ΔH;

Compute the propagation time for each layer:

Δt _l = ΔH/c _l

Among them, c _l represents the sound velocity corresponding to the lth gradient layer; 1≤l≤N _H

Then the accumulative time t _z of the propagation time of each layer is:

When t _z ≥ 2r _s0 /C, the number of layers of the corresponding gradient layer is solved to be n _s ;

Then the corrected target depth for:

Indicates the sound velocity corresponding to the n _s gradient layer, is the final estimated depth of the target in the water.

As an improvement of the above system, the specific implementation process of the target three-dimensional information calculation module is as follows:

Take the cross array as the body, establish a body coordinate system, the origin is at the intersection of the horizontal matrix and the vertical matrix, the horizontal matrix is to the right as the x direction, the vertical matrix is downward as the z direction, and the y direction is determined according to the right-hand rule;

Then in this coordinate system, the three-dimensional position of the target is:

Compared with the prior art, the present invention has the advantages of:

1. The method of the present invention improves the adaptability and accuracy of the target depth measurement system, and reduces the complexity of the measurement system;

2. The method of the present invention can not only estimate the depth of the target, but also obtain accurate three-dimensional information of the target, with a small amount of calculation and easy implementation.

Description of drawings

FIG. 1 is a flow chart of a method for measuring three-dimensional information of a target based on a cross array provided in Embodiment 1 of the present invention;

Fig. 2 is a schematic diagram of a cross array provided by Embodiment 1 of the present invention;

Fig. 3 (a) is the acoustic image of a frame horizontal direction that the example of the present invention provides;

Fig. 3 (b) provides a vertical acoustic image of a frame for the example of the present invention;

Fig. 4 is a schematic diagram of the sound velocity profile used in the examples of the present invention.

Detailed ways

The present invention will be described in detail below according to the drawings and specific embodiments.

Example 1

As shown in Figure 1, Embodiment 1 of the present invention provides a method for measuring three-dimensional information of a target based on a cross array, the method comprising:

Step 101) the design of the cross array, adopting the horizontal base array and the vertical base array cross array as the receiving base array, both share a transmitting base array; the transmitting base array and the vertical base array are on a straight line, and the transmitting base array is on the The detection range is the lower front; the cross array is installed on the bow of the carrier, and the schematic diagram of the cross array is shown in Figure 2.

Taking the cross array as the body, establish a body coordinate system. The origin is at the intersection of the horizontal matrix and the vertical matrix.

Step 102) Using the cross-array of the horizontal basic array and the vertical basic array as the receiving basic array to receive the echo data, respectively perform dynamic focusing beamforming processing on the element domain echo data of the horizontal basic array and the vertical basic array to form a horizontal-distance two-dimensional multi-dimensional Beam acoustic image and vertical-distance two-dimensional multi-beam acoustic image;

The model of the echo signal data of one frame element, assuming that the number of array elements of the horizontal receiving array is M _h , the linear uniform array, the distance between adjacent array elements is d _h , and the number of array elements of the vertical receiving array is M _v , Linear uniform array, the distance between adjacent array elements is d _v , the received echo signals are x _h (t) and x _v (t) respectively, and the dynamic focusing reception pre-forming multi-beam forming is performed:

in, and are the weighted vectors of the horizontal matrix and the vertical matrix respectively, θ _i represents the multi-beam pointing angle, the angle range is [θ _min ,θ _max ], θ _min is the minimum angle, θ _max is the maximum angle, and They are horizontal-distance acoustic image data and vertical-distance acoustic image data respectively, forming a two-dimensional image.

Step 103) For the horizontal-distance two-dimensional image, the threshold and target model fusion detection method is used to estimate the distance information range of the target, and according to the range near the target distance estimated by the horizontal-distance image, in the vertical-distance image, each The beam uses the energy center detection method to estimate the energy concentration interval and the corresponding energy value on each beam, and uses the dynamic threshold detection method to eliminate non-target points in the energy interval, and then uses the amplitude time weighted average to obtain the target scattering echo arrival time;

Step 103) further comprises:

Step 103-1) In the cross array, the horizontal receiving array is the main detection array, and the target detection is realized according to the target echo amplitude and combined with the number of target pixels. Set the target strength of the detection target as TS ₀ , the sound source level of the transmitting array as SL ₀ , and the target distance as R ₀ , the calculated echo signal strength EL ₀ of the target is

EL ₀ ＝SL ₀ -TL ₀ (R ₀ )+TS ₀

Among them, TL ₀ (R ₀ ) is the propagation loss related to the distance of the target point, and according to the receiving sensitivity of the horizontal receiving matrix, the target echo signal voltage is calculated,

V ₀ =10^((S _h +20logP _a )/20)

Among them, S _h represents the receiving sensitivity of the horizontal receiving matrix, and _Pa is the sound pressure corresponding to the received signal EL ₀ . Then, according to the gain amplification of the receiving circuit system and the gain of the beam forming, the signal amplitude A ₀ from the target in the beam domain is estimated, and the signal strength is obtained through statistics of multiple test data.

The detected underwater targets generally have a regular shape, and the number of pixels mapped to the acoustic image is basically fixed, and the number of pixels N ₀ is obtained through the statistics of multiple test data.

Combining the signal amplitude A ₀ as the detection threshold and the number of pixel points N ₀ of the target model, the detection of the horizontal array target is realized, and the horizontal distance position of the target is estimated and horizontal angle information

Step 103-2) Estimating the distance position of the target according to the horizontal matrix estimated in step 103-1) Since the target point is the intersection point of the horizontal-distance acoustic image and the vertical-distance acoustic image, according to the intersection characteristics of the horizontal receiving array and the vertical receiving array, the vertical-distance two-dimensional data is processed next, and in a certain area (r ₀ is the distance interval set according to the test application scenario), the energy center detection method is used to detect the target of each beam in the vertical-distance area, and the energy concentration interval and corresponding energy value on each beam are estimated.

According to the received signal type and the transmitted pulse width, the time resolution in the range direction is calculated as τ. Considering the extension of the echo signal, the energy estimation interval T _d is selected, and the distance interval is divided by the energy estimation interval T _d Divided into K energy intervals, the energy of each interval is expressed as

Among them, t _j is the starting moment of the jth energy interval, is the amplitude value of the j-th energy interval of the i-th beam vertically. Sorting is performed according to the energy values of the K intervals, and it is determined that the energy concentration interval corresponding to the maximum energy E _max is t _k to t _k +T _d . Calculate the average value of the data amplitude in this interval for dynamic threshold detection, eliminate non-target points in the energy interval, and finally use the amplitude time weighting method to estimate the arrival time and arrival time t _{a_m} of multiple beam target scattered echoes

Among them, N _b is the number of horizontal receiving beams. Therefore, the time value t _{a_m} and the corresponding amplitude value of the suspected target on each beam are estimated.

The above target model is mapped to the number N ₀ of pixels on the image. The above-mentioned energy is uniformly distributed, and the selected energy estimation interval T _d is 4τ, and this width is determined by the number of scattering points of the target.

Step 104) For the vertical-range data, perform dynamic threshold detection on the suspected target points of N _b multiple beams, and then estimate N _s suspected targets according to the number of beams greater than the threshold and the number of beams smaller than the threshold The arrival time value of the echo and the corresponding beam angle can obtain the possible distance and angular position of the target. According to the installation angle of the array and the array structure parameters of the array, the depth of the seabed and the sea surface is estimated, and the depth information of the target is estimated according to the triangular geometric relationship of the array, and the target depth is corrected according to the sound velocity profile.

Above-mentioned step 104) further comprises:

Step 104-1) Based on the suspected target points of multiple beams estimated in step 102), dynamic threshold detection is performed, and then non-suspected target points are eliminated according to the number of beams greater than the threshold and the number of beams smaller than the threshold, and N The arrival time values of _s suspected target echoes and the corresponding beam angles, and the target point curve is drawn in the acoustic map.

Step 104-2) converting the vertical-distance rectangular acoustic map data obtained in step 102) into fan-shaped acoustic map display data,

Among them, rr _j is the distance information in the fan-shaped acoustic map, C is the underwater sound velocity, T _j is the sound wave propagation time, θ _i,j is the angle information in the fan-shaped image, and x _i is the abscissa in the histogram.

Suppose the depth of the sonar array from the water surface is H _m , the depth of the seabed is H _d , and the pitch angle of the array is According to the image sonar fan map mapping theory, if the seabed is a flat seabed, the mapping of the sea bottom and the sea surface in the fan-shaped sound map is basically a vertical line, then the depth coordinate x _m0 of the sea surface in the fan-shaped map and the bottom in the fan-shaped map The depth coordinates x _d0 in are respectively

Among them, φ _min and φ _max are the minimum angle and maximum angle of the vertical fan diagram respectively, and the arrival time values and corresponding beam angles of the N _s suspected target echoes estimated in step 104-1) are converted into fan-shaped The depth in the figure is Since the target is a floating target in the water, the suspected target is located between the sea surface and the seabed in the depth information, and the judgment condition is

x _m0 < x _si < x _d0 (i=1,2,3,…,N _s )

Further exclude the suspected targets outside the sea surface and the seabed, and then perform dynamic threshold detection on the screened suspected targets to estimate the vertical distance and angle (r _s0 , φ _s0 ) corresponding to the point with the maximum amplitude, and according to the basis The triangular geometric relationship of the array to obtain the depth information of the target for.

Step 104-3) Since the sounding array is mainly a vertical receiving array, in the actual ocean environment, the sound ray is bent, which affects the longitude of the target sounding, and the target sounding should be corrected for sound ray bending according to the sound velocity profile. According to the vertical information distance and angle (rs _{0 , φ s0 )} of the target detected in step 104-2), combined with the sound velocity profile, the depth direction is evenly layered, which can reduce the computational complexity. According to the sounding accuracy requirements, the The depth is divided into N _H layers, each layer has a depth of ΔH, and according to Snell's law

Among them, α _i is the grazing angle of the sound ray in the _i -th layer, and ci is the corresponding sound velocity. The sound ray correction process is:

Δt _i =ΔH/c _i

The correction can be stopped when the accumulative time t of the propagation time of each layer reaches the target propagation time, that is, t _z ≥ 2r _s0 /C, and the corresponding gradient layer number is n _s , then the corrected target depth for

but For the depth of the target in the water that is finally estimated, combine the target horizontal direction information that is estimated in step 103): the horizontal direction distance position of the target and horizontal angle information The three-dimensional information of the target can be obtained:

Example 2

Embodiment 2 of the present invention provides a cross-array-based target three-dimensional information measurement system, which includes:

A cross array, the cross array includes: a receiving array and a transmitting array, the receiving array includes a horizontal receiving array and a vertical receiving array, both of which share a transmitting array;

The two-dimensional multi-beam image generation module is used to perform dynamic focusing beamforming processing on the echo data of the horizontal array and the vertical array element domain to form a horizontal-distance two-dimensional multi-beam acoustic image and a vertical-distance two-dimensional multi-beam Acoustic image;

The target horizontal direction information estimation module is used to jointly detect the horizontal direction information of the target by using the horizontal image using the amplitude and the target model,

Assuming that the target strength of the detection target is TS ₀ , the sound source level of the transmitting array is SL ₀ , and the target distance is R ₀ , the calculated echo signal strength EL ₀ of the target is

EL ₀ ＝SL ₀ -TL ₀ (R ₀ )+TS ₀

Among them, TL ₀ (R ₀ ) is the propagation loss related to the distance of the target point, and according to the receiving sensitivity of the horizontal receiving matrix, the target echo signal voltage is calculated,

V ₀ =10^((S _h +20logP _a )/20)

Among them, S _h represents the receiving sensitivity of the horizontal receiving matrix, and _Pa is the sound pressure corresponding to the received signal EL ₀ . Then, according to the gain amplification of the receiving circuit system and the gain of the beam forming, the signal amplitude A ₀ from the target in the beam domain is estimated, and the signal strength is obtained through statistics of multiple test data.

The detected underwater targets generally have regular shapes, and the number of pixels mapped to the distance direction of the acoustic image is basically fixed, and the number of pixels N ₀ is obtained through statistics of multiple test data.

Combining the signal amplitude A ₀ as the detection threshold and the distance pixel number N ₀ of the target model, the detection of the horizontal array target is realized, and the horizontal distance position of the target is estimated

Vertical target detection module, including: vertical suspected target detection sub-module and dynamic detection sub-module,

The vertical suspected target detection sub-module is used to estimate the distance position of the target according to the estimated horizontal matrix Since the target point is the intersection point of the horizontal-distance acoustic image and the vertical-distance acoustic image, according to the intersection characteristics of the horizontal receiving array and the vertical receiving array, the vertical-distance two-dimensional data is processed next, and in a certain area (r ₀ is the distance interval set according to the test application scenario), the energy center detection method is used to detect the target of each beam in the vertical-distance area, and the energy concentration interval and corresponding energy value on each beam are estimated.

According to the received signal type and the transmitted pulse width, the time resolution in the range direction is calculated as τ. Considering the extension of the echo signal, the energy estimation interval T _d is selected, and the distance interval is divided by the energy estimation interval T _d Divided into K energy intervals, the energy of each interval is expressed as

Among them, t _j is the starting moment of the jth energy interval, is the amplitude value of the j-th energy interval of the i-th beam vertically. Sorting is performed according to the energy values of the K intervals, and it is determined that the energy concentration interval corresponding to the maximum energy E _max is t _k to t _k +T _d . Calculate the average value of the data amplitude in this interval for dynamic threshold detection, eliminate non-target points in the energy interval, and finally use the amplitude time weighting method to estimate the arrival time and arrival time t _{a_m} of multiple beam target scattered echoes

Among them, N _b is the number of horizontal receiving beams. Therefore, the time value t _{a_m} and the corresponding amplitude value of the suspected target on each beam are estimated.

The above target model is mapped to the number N ₀ of pixels on the image. The above-mentioned energy is uniformly distributed, and the selected energy estimation interval T _d is 4τ, and this width is determined by the number of scattering points of the target.

The dynamic detection sub-module is used to estimate suspected target points of multiple beams, perform dynamic threshold detection, and then eliminate non-suspect target points according to the number of beams greater than the threshold and the number of beams smaller than the threshold, and estimate N _s The arrival time value of the suspected target echo and the corresponding beam angle, draw the target point curve in the acoustic map.

The depth information estimation module is used to convert the rectangular acoustic image into a fan-shaped acoustic image by using an image conversion algorithm, and estimate the vertical information of the suspected target point in the fan-shaped image; use the position information of the fan-shaped image to estimate the depth information of the seabed and sea surface, and then filter Get out of the target point and get the target depth information.

Convert vertical-distance to rectangular acoustic map data into fan-shaped acoustic map display data,

Among them, rr _j is the distance information in the fan-shaped acoustic map, C is the underwater sound velocity, T _j is the sound wave propagation time, θ _i,j is the angle information in the fan-shaped image, and x _i is the abscissa in the histogram.

Suppose the depth of the sonar array from the water surface is H _m , the depth of the seabed is H _d , and the pitch angle of the array is According to the image sonar fan map mapping theory, if the seabed is a flat seabed, the mapping of the sea bottom and the sea surface in the fan-shaped sound map is basically a vertical line, then the depth coordinate x _m0 of the sea surface in the fan-shaped map and the bottom in the fan-shaped map The depth coordinates x _d0 in are respectively

Among them, φ _min and φ _max are the minimum and maximum angles of the vertical fan diagram respectively, and the estimated arrival time values and corresponding beam angles of the N _s suspected target echoes are converted into the depth in the fan diagram as Since the target is a floating target in the water, the suspected target is located between the sea surface and the seabed in the depth information, and the judgment condition is

x _m0 < x _si < x _d0 (i=1,2,3,…,N _s )

Further exclude the suspected targets outside the sea surface and the seabed, and then perform dynamic threshold detection on the screened suspected targets to estimate the vertical distance and angle (r _s0 , φ _s0 ) corresponding to the point with the maximum amplitude, and according to the basis The triangular geometric relationship of the array to obtain the depth information of the target for.

The depth correction module is used to use sound ray bending to correct the target depth. According to the above-mentioned detected target vertical information distance and angle (rs _s0 , φ _s0 ), combined with the sound velocity profile, the depth direction is evenly layered, which can reduce the calculation Complexity, according to the sounding accuracy requirements, the depth is divided into N _H layers, and the depth of each layer is ΔH, and according to Snell's law:

Among them, α _i is the grazing angle of the sound ray in the _i -th layer, and ci is the corresponding sound velocity. The sound ray correction process is

Δt _i =ΔH/c _i

The correction can be stopped when the accumulative time t of the propagation time of each layer reaches the target propagation time, that is, t _z ≥ 2r _s0 /C, and the corresponding gradient layer number is n _s , then the corrected target depth for

Indicates the sound velocity corresponding to the n _s gradient layer, is the final estimated depth of the target in the water.

The three-dimensional information calculation module of the target is used to combine the depth of the target with the horizontal direction information of the target to obtain the three-dimensional information of the target.

example

In this example, the system parameters are: the target depth measurement system based on the cross array, the receiving transducer array is the horizontal receiving array and the vertical receiving array as the cross array, the data used are the data obtained from the lake test, the base array The depth from the water surface is 4.5 meters, the depth of the lake bottom is 65 meters, the speed of sound is 1480m/s, the number of horizontal receiving arrays is 200, the number of vertical receiving arrays is 30, the pitch angle of the array is 0.7°, and only one frame is processed Data, the processing results are as follows.

From Figure 3(a), Figure 3(b) and Figure 4, it can be seen that the horizontal information of the detected target is 272.8 meters in distance, and the horizontal azimuth angle is 1.45°. After correction, the estimated depth of the target is 9.95 meters .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the present invention. within the scope of the claims.

Claims (14)

1. A target three-dimensional information measurement method based on a cross array is realized based on the cross array, and the cross array comprises the following steps: the receiving array comprises a horizontal receiving array and a vertical receiving array which share one transmitting array; the method comprises the following steps:

respectively carrying out dynamic focusing beam forming on array element domain echo data of a receiving array to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image;

performing joint detection on the horizontal-distance two-dimensional acoustic image by adopting the signal amplitude and a target model to obtain target horizontal direction information;

target horizontal information is fused in the vertical-distance two-dimensional acoustic image, and vertical information of a plurality of suspected target points is estimated by adopting energy center and dynamic threshold joint detection; dynamic threshold detection is carried out on a plurality of suspected target points, non-suspected points are removed, and target points are obtained;

estimating the sea surface distribution at the bottom of the sea by combining the pitch angle and the structure of the cross array, and further estimating the depth of the target;

and combining the depth of the target with the horizontal information of the target to obtain the three-dimensional information of the target.

2. The method for measuring the three-dimensional information of the target based on the cross array as claimed in claim 1, wherein the dynamic focusing beam forming is performed on the array element field echo data of the receiving array respectively to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image; the method specifically comprises the following steps:

the number of the array elements of the horizontal receiving array is M_hLinear uniform array with adjacent array elements spaced by a distance d_hThe number of the array elements of the vertical receiving array is M_vLinear uniform array with adjacent array elements spaced by a distance d_vThe received echo signals are x respectively_h(t) and x_v(t) performing dynamic focused reception of pre-multi-beam forming:

wherein,andweighting vectors, theta, for horizontal and vertical receiving matrices, respectively_iIndicating a multi-beam pointing angle in an angular range [ theta ]_min,θ_max]，θ_minIs a minimum angle, θ_maxThe angle is the maximum angle, and the angle is the maximum angle,andthe horizontal-distance sonogram data and the vertical-distance sonogram data are respectively formed into a two-dimensional image.

3. The method for measuring the three-dimensional information of the target based on the cross array as claimed in claim 2, wherein the step of jointly detecting the horizontal-distance two-dimensional acoustic map by using the signal amplitude and the target model to obtain the horizontal information of the target specifically comprises the steps of:

calculating the echo signal intensity EL of the target₀：

EL₀＝SL₀-TL₀(R₀)+TS₀

Wherein SL₀Is the sound source level of the emitting array; TS (transport stream)₀For which the target intensity of the target is detected, the target being at a distance R from the intersecting array₀，TL₀(R₀) Propagation loss as a function of target point distance;

according to the receiving sensitivity of the horizontal receiving array, the voltage V of the target echo signal is calculated₀：

V₀＝10^((S_h+20log P_a)/20)

Wherein S is_hIndicating the receive sensitivity, P, of a horizontal receive array_aFor receiving a signal EL₀Corresponding sound pressure;

according to the gain amplification of the receiving circuit system and the gain of the beam forming, the signal amplitude A of the beam domain target is estimated₀；

Signal amplitude A₀As a detection threshold, combining the number N of target model pixel points₀Realizing dynamic threshold detection of the horizontal array target, thereby estimating and obtaining the horizontal distance position of the targetAnd horizontal angle information

4. The method for measuring the three-dimensional information of the target based on the cross array as claimed in claim 3, wherein the horizontal information of the target is fused in the vertical-distance two-dimensional acoustic map, and the vertical information of a plurality of suspected target points is estimated by adopting the joint detection of an energy center and a dynamic threshold; dynamic threshold detection is carried out on a plurality of suspected target points, non-suspected points are removed, and target points are obtained; the method specifically comprises the following steps:

in a regionInner, r₀Calculating the distance direction time resolution ratio tau according to the distance set according to the test application scene, the type of the received signal and the emission pulse width;

selecting an energy estimation interval T_d，T_dEstimate interval T using energy of 4 τ_dInterval the distanceIs divided into K energy intervals, and the energy of each interval is expressed as

Wherein, t_jIs the starting time of the jth energy interval,the amplitude value of the jth energy interval of the ith beam is vertically;

sorting the energy values of K intervals to obtain the maximum energy value E_maxThe corresponding k-th energy concentration interval is [ t ]_k,t_k+T_d]；

To [ t ]_k,t_k+T_d]The data amplitude values in the interval are averaged to carry out dynamic threshold detection, non-target points in the energy interval are eliminated, and finally the arrival time t of the scattering echoes of the multiple beam targets is estimated by adopting an amplitude-time weighting method_{a_m}：

Wherein N is_bIs the number of horizontal receive beams; thereby estimating the time value t of the suspected target on each beam_{a_m}And a corresponding amplitude value;

performing dynamic threshold detection on suspected target points of a plurality of beams, taking the number of beams larger than the threshold and the number of beams smaller than the threshold as non-suspected target points, and removing the non-suspected target points to obtain N_sEstimating N for each suspected target_sAnd drawing a target point curve in the vertical-distance acoustic diagram by the arrival time value of the suspected target echo and the corresponding beam angle.

5. The method for measuring the three-dimensional information of the target based on the cross array as claimed in claim 4, wherein the estimating the sea surface distribution at the sea bottom and further the depth of the target by combining the pitch angle and the structure of the cross array specifically comprises:

converting the vertical-distance rectangular sonogram data into sector sonogram display data:

wherein rr is_vDistance information in a sector acoustic diagram, C is underwater sound velocity, T_jIs the acoustic wave propagation time, θ_u,vIs the angular information, x, in the sector map_uIs the abscissa in the vertical-distance direction rectangular acoustic diagram; u and v are positiveAn integer number;

depth coordinate x of sea surface in sector graph_m0And depth coordinate x of the sea floor in the sector map_d0Respectively as follows:

wherein H_mThe depth of the cross array from the sea surface; h_dThe depth of the cross array from the sea floor is the pitch angle of the cross array matrixφ_minAnd phi_maxRespectively the minimum angle and the maximum angle of the vertical sector graph;

will N_sThe arrival time value and the corresponding beam angle of each suspected target echo are converted into the depth of a sector graph

According to the following judgment conditions

x_m0＜x_si＜x_d0,i＝1,2,3,…,N_s

Further excluding suspected targets outside the sea surface and the sea floor;

and carrying out dynamic threshold detection on the screened suspected target, and estimating the vertical distance and the angle (r) corresponding to the point with the maximum amplitude_s0,φ_s0) And obtaining the depth information of the target according to the triangular geometric relationship of the cross arrayComprises the following steps:

6. the method for measuring three-dimensional information of the target based on the cross array as claimed in claim 5, wherein the estimating the depth of the target further comprises: and correcting the target depth by utilizing the sound ray bending:

according to the vertical information distance and angle (r) of the target_s0,φ_s0) And combining the sound velocity profile to uniformly layer the depth direction and divide the depth into N_HLayers, each layer having a depth Δ H;

calculating the propagation time of each layer:

Δt_l＝ΔH/c_l

wherein, c_lRepresenting the sound velocity corresponding to the ith gradient layer; l is more than or equal to 1 and less than or equal to N_H

The cumulative time t of the propagation times of the layers_zComprises the following steps:

when t is_z≥2r_s0when/C, the number of the corresponding gradient layers is solved to be n_s；

The corrected target depthComprises the following steps:

denotes the n-th_sThe corresponding speed of sound of the gradient layer,the depth of the target in the water is finally estimated.

7. The method for measuring the three-dimensional information of the target based on the crossbar array according to claim 6, wherein the step of combining the depth of the target with the horizontal information of the target to obtain the three-dimensional information of the target specifically comprises the following steps:

establishing a body coordinate system by taking the cross array as a body, wherein the origin is at the intersection of the horizontal array and the vertical array, the horizontal array is in the x direction towards the right, the vertical array is in the z direction downwards, and the y direction is determined according to a right-hand rule;

then under this coordinate system, the three-dimensional position of the target is:

8. a system for measuring three-dimensional information of an object based on a cross array, the system comprising:

a crossbar array, said crossbar array comprising: the receiving array comprises a horizontal receiving array and a vertical receiving array which share one transmitting array;

the two-dimensional multi-beam image generation module is used for respectively carrying out dynamic focusing beam forming on the array element domain echo data of the receiving array to form a horizontal-distance two-dimensional acoustic image and a vertical-distance two-dimensional acoustic image;

the target horizontal information estimation module is used for carrying out joint detection on the horizontal-distance two-dimensional acoustic image by adopting the signal amplitude and a target model to obtain target horizontal information;

the vertical target point detection module is used for fusing target horizontal information in a vertical-distance two-dimensional acoustic image, and estimating vertical information of a plurality of suspected target points by adopting energy center and dynamic threshold combined detection; dynamic threshold detection is carried out on a plurality of suspected target points, non-suspected points are removed, and target points are obtained;

the depth information estimation module is used for estimating the sea surface distribution at the bottom of the sea by combining the pitch angle and the structure of the cross array so as to estimate the depth of the target;

and the target three-dimensional information calculation module is used for combining the corrected target depth with the target horizontal information to obtain the target three-dimensional information.

9. The system for measuring target three-dimensional information based on the crossbar array according to claim 8, wherein the two-dimensional multi-beam image generation module is implemented by the following processes:

the number of the array elements of the horizontal receiving array is M_hLinear uniform array with adjacent array elements spaced by a distance d_hThe number of the array elements of the vertical receiving array is M_vLinear uniform array with adjacent array elements spaced by a distance d_vThe received echo signals are x respectively_h(t) and x_v(t) performing dynamic focused reception of pre-multi-beam forming:

wherein,andweighting vectors, theta, for horizontal and vertical receiving matrices, respectively_iIndicating a multi-beam pointing angle in an angular range [ theta ]_min,θ_max]，θ_minIs a minimum angle, θ_maxThe angle is the maximum angle, and the angle is the maximum angle,andthe horizontal-distance sonogram data and the vertical-distance sonogram data are respectively formed into a two-dimensional image.

10. The system for measuring the three-dimensional information of the target based on the crossbar array according to claim 9, wherein the target level information estimation module is implemented by the following steps:

calculating the echo signal intensity EL of the target₀：

EL₀＝SL₀-TL₀(R₀)+TS₀

Wherein SL₀Is the sound source level of the emitting array; TS (transport stream)₀For which the target intensity of the target is detected, the target being at a distance R from the intersecting array₀，TL₀(R₀) Propagation loss as a function of target point distance;

according to the receiving sensitivity of the horizontal receiving array, the voltage V of the target echo signal is calculated₀：

V₀＝10^((S_h+20log P_a)/20)

Wherein S is_hIndicating the receive sensitivity, P, of a horizontal receive array_aFor receiving a signal EL₀Corresponding sound pressure;

according to the gain amplification of the receiving circuit system and the gain of the beam forming, the signal amplitude A of the beam domain target is estimated₀；

Signal amplitude A₀As a detection threshold, combining the number N of target model pixel points₀Realizing dynamic threshold detection of the horizontal array target, thereby estimating and obtaining the horizontal distance position of the targetAnd horizontal angle information

11. The system of claim 10, wherein the vertical target point detection module comprises: a vertical suspected target detection submodule and a dynamic detection submodule,

the vertical suspected target detection submodule is used for detecting a suspected target on each beam in the vertical direction; the method specifically comprises the following steps:

in a regionInner, r₀Calculating the distance direction time resolution ratio tau according to the distance set according to the test application scene, the type of the received signal and the emission pulse width;

selecting an energy estimation interval T_d，T_dEstimate interval T using energy of 4 τ_dInterval the distanceIs divided into K energy intervals, and the energy of each interval is expressed as

Wherein, t_jIs the starting time of the jth energy interval,the amplitude value of the jth energy interval of the ith beam is vertically;

sorting the energy values of K intervals to obtain the maximum energy value E_maxThe corresponding k-th energy concentration interval is [ t ]_k,t_k+T_d]；

To [ t ]_k,t_k+T_d]The data amplitude values in the interval are averaged to carry out dynamic threshold detection, non-target points in the energy interval are eliminated, and finally the arrival time t of the scattering echoes of the multiple beam targets is estimated by adopting an amplitude-time weighting method_{a_m}：

Wherein N is_bIs the number of horizontal receive beams; thereby estimating the time value t of the suspected target on each beam_{a_m}And a corresponding amplitude value;

the dynamic detection submodule is used for carrying out dynamic threshold detection on suspected target points of a plurality of beams, taking the number of the beams larger than the threshold and the number of the beams smaller than the threshold as non-suspected target points, and removing the non-suspected target points to obtain N_sEstimating N for each suspected target_sAnd drawing a target point curve in the vertical-distance acoustic diagram by the arrival time value of the suspected target echo and the corresponding beam angle.

12. The system for measuring the three-dimensional information of the target based on the crossbar array according to claim 11, wherein the depth information estimation module is implemented by the following steps:

converting the vertical-distance rectangular sonogram data into sector sonogram display data:

wherein rr is_vDistance information in a sector acoustic diagram, C is underwater sound velocity, T_jIs the acoustic wave propagation time, θ_u,vIs the angular information, x, in the sector map_uIs the abscissa in the vertical-distance direction rectangular acoustic diagram; u and v are positive integers;

depth coordinate x of sea surface in sector graph_m0And depth coordinate x of the sea floor in the sector map_d0Respectively as follows:

wherein H_mThe depth of the cross array from the sea surface; h_dThe depth of the cross array from the sea floor is the pitch angle of the cross array matrixφ_minAnd phi_maxRespectively the minimum angle and the maximum angle of the vertical sector graph;

will N_sThe arrival time value and the corresponding beam angle of each suspected target echo are converted into the depth of a sector graph

According to the following judgment conditions

x_m0＜x_si＜x_d0,i＝1,2,3,…,N_s

Further excluding suspected targets outside the sea surface and the sea floor;

and carrying out dynamic threshold detection on the screened suspected target, and estimating the vertical distance and the angle (r) corresponding to the point with the maximum amplitude_s0,φ_s0) And obtaining the depth information of the target according to the triangular geometric relationship of the cross arrayComprises the following steps:

13. the method for measuring the three-dimensional information of the target based on the crossbar array according to claim 12, wherein the system further comprises a depth information estimation module, and the method is realized by the following specific processes:

according to the vertical information distance and angle (r) of the target_s0,φ_s0) And combining the sound velocity profile to uniformly layer the depth direction and divide the depth into N_HLayers, each layer having a depth Δ H;

calculating the propagation time of each layer:

Δt_l＝ΔH/c_l

wherein, c_lRepresenting the sound velocity corresponding to the ith gradient layer; l is more than or equal to 1 and less than or equal to N_H

The cumulative time t of the propagation times of the layers_zComprises the following steps:

when t is_z≥2r_s0when/C, the number of the corresponding gradient layers is solved to be n_s；

The corrected target depthComprises the following steps:

denotes the n-th_sThe corresponding speed of sound of the gradient layer,the depth of the target in the water is finally estimated;

14. the method for measuring the target three-dimensional information based on the crossbar array according to claim 13, wherein the target three-dimensional information calculation module is implemented by the following steps:

establishing a body coordinate system by taking the cross array as a body, wherein the origin is at the intersection of the horizontal array and the vertical array, the horizontal array is in the x direction towards the right, the vertical array is in the z direction downwards, and the y direction is determined according to a right-hand rule;

then under this coordinate system, the three-dimensional position of the target is: