CN115407340A - Bistatic positioning method based on grid matching under variable acoustic velocity - Google Patents

Abstract

The invention provides a bistatic positioning method under variable acoustic velocity based on grid matching, which is characterized in that firstly, a time delay information matching method is applied to bistatic positioning, compared with the traditional elliptical positioning, the problem of positioning error caused by acoustic ray bending in bistatic positioning is solved, and the positioning accuracy is improved. The invention carries out grid matching based on the time delay information, divides the possible areas of the target into grids, independently calculates the corresponding time delay information by taking each grid as the target, and matches the time delay information with the actual sound ray propagation time to realize target positioning.

Description

A Bistatic Positioning Method Based on Grid Matching under Variable Sound Velocity

technical field

The invention belongs to the field of underwater acoustic positioning, and relates to a bistatic positioning method, in particular to a bistatic positioning method in a variable sound velocity environment based on grid time delay information matching.

Background technique

Bistatic sonar separates the transmitting equipment from the receiving equipment, which is an important means to avoid the influence of platform noise and increase the detection distance. The basic method of bistatic positioning is the ellipse positioning method. When the sound wave is emitted by the transmitting base station and scattered by the target to reach the receiving base station, the total propagation distance is calculated as the long axis value of the ellipse based on its propagation time. The transmitting and receiving base stations are the focus, and the target is here On the ellipse trajectory, multiple ellipses intersect to determine the target position.

However, due to the non-uniform characteristics of the seawater medium, the sound velocity in seawater is affected by temperature, salinity and depth, and the sound ray is bent. At this time, if the target position is still calculated according to the constant sound velocity, a positioning error will occur. For sound ray bending, Wu Deming proposed a sound ray correction method suitable for hyperbolic positioning systems in "An Iterative Method for Sound Ray Correction" in 1992. This method approximates the sound velocity distribution to a layered and equal gradient distribution , and use an iterative method to achieve target positioning. At the end of the last century, Vincent, H.T and Hu, S.L.J combined the theoretical model of positioning with actual physics in "Geodetic position estimation of underwater acoustic sensors", and introduced an effective sound velocity for each point of the direct sound propagation space in the deep sea environment. Through the effective The speed of sound is used to determine the accurate distance and get more accurate target position information. In 2002, Wang Yan and Liang Guolong et al. proposed an iterative method to process the test data of the long baseline underwater acoustic positioning system in their paper "A Sound Ray Correction Method Applicable to Long Baseline Underwater Acoustic Positioning System", and obtained better processing results. . In 2009 "A Table Lookup Method for Sound Ray Correction", Liang Minzan used the sound ray correction table lookup method to process the sea test data, and verified that the algorithm can effectively improve the positioning performance. In 2019, Sun Dajun and others proposed a sound velocity correction algorithm based on an effective sound velocity table in the article "Sound velocity correction based on effective sound velocity for underwater acoustic positioning systems". This algorithm is suitable for ultra-short baseline positioning systems and can be offline based on the sound ray tracking method. Calculate the effective sound velocity of all positions in the area, and use the calculation results at all positions to form an effective sound velocity table. When it is applied, it only needs to be called according to the depth, which greatly improves the calculation speed and ensures the positioning accuracy.

The above method basically solves the problem caused by the bending of sound rays in the case of single base, but due to the active and passive combination of dual bases and the separation of sending and receiving, only the total propagation time from the transmitting station to the receiving station through the target scattering can be obtained. The line correction method is difficult to apply.

Contents of the invention

The purpose of the present invention is to provide an underwater bistatic positioning method based on grid matching, which can overcome the failure of the bistatic elliptical positioning method caused by sound ray bending at variable sound speeds, and improve positioning accuracy.

The object of the present invention is achieved like this: comprise the following steps:

Step 1. Determine environmental parameters, including sound velocity distribution, ocean depth, and sound ray propagation environmental parameters of seabed topography.

Step 2, input the deployment parameters of the bistatic base station, including the location information of the transmitting station and the receiving station, and the actual measured value t of the total propagation time of the sound rays under the deployment parameters.

得到每个网格的总传播时间

Step 3: Divide the grid within the target search range, traverse the grid, and calculate the direct sound ray propagation time t ₁ from the transmitting station to a certain grid and the direct sound ray propagation time t ₂ from the receiving station to a certain grid, by

Get the total travel time for each grid

与给定声线总传播时间t的欧几里得距离，设定时延误差检测门限Δt，若

则保存该网格坐标，将该网格位置标记为亮点；若

则不保留网格坐标，继续计算下一网格。计算完成所有网格后的亮点坐标组成亮点图1。Step 4, calculate the propagation time corresponding to each grid in turn

Euclidean distance from the total travel time t of a given sound ray, set the delay error detection threshold Δt, if

Then save the grid coordinates and mark the grid position as a bright spot; if

Then the grid coordinates are not reserved, and the calculation of the next grid is continued. The coordinates of the bright spots after all grids are calculated form the bright spot map 1.

Step 5, change the deployment parameters of the bistatic base station, repeat steps 2 to 4, and obtain a new bright spot map 2.

Step 6: Take the intersection of the coordinates of the bright spots in the bright spot map 1 and the bright spot map 2, and obtain the result of target positioning coordinates.

In the above step 3, the target search range is discretized into N grids. The more the number of grids, the lower the delay error detection threshold, the higher the positioning accuracy, and the greater the calculation amount. The calculation process uses the ray acoustic model.

In the above steps 5 and 6, since the delay values corresponding to different grids may be the same, a large number of false target positions are retained in a single simulation, and a large number of false positions can be eliminated by repeatedly obtaining the intersection of bright spot maps.

The present invention performs grid matching based on time delay information, divides the possible target area into grids, and calculates corresponding time delay information for each grid as a target, and matches the time delay information with the actual sound ray propagation time to realize target positioning.

Compared with the prior art, the beneficial effect of the present invention is: the grid matching-based bistatic positioning method under variable sound velocity proposed by the present invention firstly applies the delay information matching method to bistatic positioning, compared with the traditional The ellipse positioning solves the positioning error problem caused by the sound ray bending in the bistatic positioning, and improves the positioning accuracy.

Concrete advantage of the present invention is as follows:

1. Shorten the positioning calculation time. The above steps 1 and 3 can be completed before positioning the target, that is, the propagation time required by each grid can be calculated in advance, and only the time delay information of each grid needs to be called during positioning to shorten the calculation time.

2. Overcome the problem of positioning error caused by sound ray bending. After the sound ray is bent, the single-base sound ray correction method cannot be directly applied to the bistatic background, and the positioning accuracy of the traditional elliptical positioning in bistatic positioning is greatly reduced after the sound ray is bent. The time delay information is used for matching to achieve positioning, and the change of sound velocity can be reflected in the time delay information of each grid, which improves the positioning accuracy.

Description of drawings

Figure 1 is a grid matching flow chart;

Fig. 2 is an environmental sound velocity profile in the implementation example;

Fig. 3 is the bright spot diagram 1 corresponding to transmitting station 1 in the implementation example;

Fig. 4 is the bright spot diagram 2 corresponding to the transmitting station 2 in the implementation example;

Fig. 5 is the intersection diagram of bright spots corresponding to two transmitting stations in the implementation example;

Fig. 6 is a diagram of the positioning result in the implementation example.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The implementation case of the present invention is given as follows in conjunction with specific parameters:

(1) Determination of environmental parameters: the sound velocity profile is shown in Figure 2, using the horizontal seabed, the ocean depth is 5000m, the seabed parameters are seabed sound velocity 1600m/s, seabed density 1.83g/cm ³ , seabed attenuation coefficient 0.8dB/λ , input it into the sound field modeling software BELLHOP;

(2) Determine the deployment parameters of the bistatic base station: the target area is the horizontal distance range of 0-15km, the coordinate unit is km, the depth range is 0-2000m, the coordinate unit is m, the coordinates of the transmitting station 1 (0,1000), and the coordinates of the receiving station (15, 4990).

网格坐标与

一一对应。(3) Divide the target area into 100×30(m) grids, traverse the grids, calculate t ₁ and t ₂ through BELLHOP and sum them to get

grid coordinates with

One to one correspondence.

与t的欧几里得距离，设定时延误差检测门限Δt＝10ms。若

则保存该网格坐标，将该网格标记为亮点；若

删除该网格坐标，继续匹配下一网格。将保留的坐标标记为亮点，形成亮点图1，如附图3所示。(4) Obtain the total propagation time of the actual measured sound ray t=10.8604s, and calculate the corresponding propagation time of each grid

Euclidean distance from t, set time delay error detection threshold Δt=10ms. like

Then save the grid coordinates and mark the grid as a bright spot; if

Delete the grid coordinates and continue to match the next grid. Mark the reserved coordinates as bright spots to form a bright spot map 1, as shown in Figure 3.

(5) Change the coordinates of transmitting station 2 in the layout parameters of the bistatic base station to (0,2000), repeat (2) to (4), and obtain the bright spot map 2, as shown in Figure 4, for the two reserved The intersection of the target positions is shown in Figure 5, and the obtained intersection point is the target positioning result, as shown in Figure 6.

Claims (3)

1. A bistatic positioning method based on grid matching under variable sound velocity, characterized in that the steps are as follows: Step 1: Determine environmental parameters, including sound velocity distribution, ocean depth, and sound ray propagation environmental parameters of seabed topography; Step 2: Input the deployment parameters of the bistatic base station, including the location information of the transmitting station and the receiving station, and the actual measured value t of the total propagation time of the sound rays under the deployment parameters; Step 3: Divide the grid within the target search range, traverse the grid, and calculate the direct sound ray propagation time t ₁ from the transmitting station to a certain grid and the direct sound ray propagation time t ₂ from the receiving station to a certain grid, respectively, by

Get the total travel time for each grid

Step 4: Calculate the propagation time corresponding to each grid in turn

Euclidean distance from the total travel time t of a given sound ray, set the delay error detection threshold Δt, if

Then save the grid coordinates and mark the grid position as a bright spot; if

Then the grid coordinates are not reserved, and the calculation of the next grid is continued. The coordinates of the bright spots after all the grids are calculated form the bright spot map 1; Step 5: Change the deployment parameters of the bistatic base station, repeat steps 2 to 4, and get a new bright spot map 2; Step 6: Take the intersection of the coordinates of the bright spots in the bright spot map 1 and the bright spot map 2, and obtain the result of the target positioning coordinates. 2. A kind of bistatic positioning method based on grid matching according to claim 1, characterized in that, in step 3, the target search range is discretized into N grids, the more the grid number, The lower the time delay error detection threshold, the higher the positioning accuracy and the greater the calculation amount. The calculation process uses the ray acoustic model. 3. A grid-matching-based bistatic positioning method with variable sound velocity according to claim 1, characterized in that, in steps 5 and 6, the delay values corresponding to different grids may be the same, and a single simulation retains A large number of false target positions can be obtained by repeatedly obtaining the intersection of bright spot maps to eliminate a large number of false positions.

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