A method and system for locating non-cooperative targets in water based on iterative neighborhood search

Abstract

The present invention relates to an underwater target positioning method, in particular to an underwater non-cooperative target positioning method and system based on neighborhood iterative search, obtaining an estimated search area of ​​an underwater non-cooperative target, deploying a distributed long baseline measurement system and measuring corresponding information, narrowing the search range by iteratively updating the current search area in the estimated search area based on a domain iterative search strategy, the current search area is an optimal sub-area selected from a number of current sub-areas by a current eigenvalue sequence obtained by a eigenfunction, and the number of current sub-areas are formed by cutting the current search area updated in the previous iteration according to the current iteration step length, until a preset iteration termination condition is reached, and the position of the selected optimal sub-area is the position of the underwater non-cooperative target. The present invention has a simple principle and a small amount of calculation, is more suitable for application in real-time systems and embedded systems, and solves the problem that the prior art is easily subject to geometric constraints of positioning nodes, resulting in unsatisfactory final positioning results.

Description

Technical Field

[0001] The invention relates to an underwater target positioning method, and in particular to an underwater non-cooperative target positioning method and system based on neighborhood iterative search. Background Art

[0002] The positioning of non-cooperative targets in water plays an important role in many fields such as military, civil, scientific research and public safety. At present, the usual practice is to measure the time delay difference between the signal sent by the target and the positioning nodes, and then obtain the distance difference between the target and the positioning nodes to achieve the positioning of non-cooperative targets. This method requires complex mathematical operations and a large amount of data processing, and has high requirements on the computing power of the processor. In addition, the high amount of calculation of this method may cause delays, affect real-time performance, and lead to unsatisfactory application effects in real-time systems and embedded systems. This method is also susceptible to the geometric constraints of the positioning nodes, especially when the three commonly used positioning nodes are used for triangulation. If the node layout is unreasonable, the final positioning result will be unsatisfactory.

[0003] In summary, the current technology is not suitable for real-time systems and embedded systems, and is easily constrained by the geometry of the positioning nodes, resulting in unsatisfactory final positioning results. Summary of the invention

[0004] The purpose of this application is to provide a method and system for locating non-cooperative targets in water based on iterative neighborhood search, so as to solve the problem that the current technology is not suitable for real-time systems and embedded systems, and is easily constrained by the geometry of the positioning nodes, resulting in unsatisfactory final positioning results. In view of the above problems, this application provides a method and system for locating non-cooperative targets in water based on iterative neighborhood search.

[0005] In the first aspect, the present application provides a method for locating non-cooperative targets in water based on neighborhood iterative search, the method comprising: obtaining an estimated search area for underwater non-cooperative targets, deploying a distributed long baseline measurement system based on the estimated search area, the distributed long baseline measurement system comprising a plurality of measurement units, the monitoring unit comprising a pair of underwater monitoring components and above-water monitoring components; based on a domain iterative search strategy, narrowing the search range by iteratively updating the current search area within the estimated search area, the current search area being the optimal sub-area selected from a plurality of current sub-areas by a current eigenvalue sequence obtained by a eigenfunction, the plurality of current sub-areas being formed by cutting the current search area updated in the previous iteration according to the current iteration step, and obtaining a plurality of current The three-dimensional coordinates of the position of the sub-area are obtained until the preset iteration termination condition is reached. The position of the optimal sub-area screened out is the position of the underwater non-cooperative target, wherein the current eigenvalue sequence obtained by the characteristic function: the underwater monitoring component obtains the acoustic signal emitted by the underwater non-cooperative target in real time, and extracts the time when the acoustic signal arrives at each measuring unit. At the same time, the above-water monitoring component obtains the current three-dimensional coordinates of the position of each measuring unit when the acoustic signal arrives at each measuring unit; the underwater monitoring component measures the underwater sound speed of the estimated search area, and inputs the time when the acoustic signal arrives at each measuring unit, the current three-dimensional coordinates of the position of each measuring unit, the three-dimensional coordinates of the position of several current sub-areas and the underwater sound speed as parameters into the characteristic function to obtain the current eigenvalue sequence.

[0006] In the second aspect, the application provides an underwater non-cooperative target positioning system based on neighborhood iterative search, the system comprising: a distributed long baseline measurement system module, the distributed long baseline measurement system module is used to obtain an estimated search area for underwater non-cooperative targets, and a distributed long baseline measurement system is deployed based on the estimated search area, the distributed long baseline measurement system comprises a plurality of measurement units, and the monitoring unit comprises a pair of underwater monitoring components and above-water monitoring components; a neighborhood iterative search module, the domain iterative search module is used to narrow the search range by iteratively updating the current search area within the estimated search area based on a domain iterative search strategy, the current search area is the optimal sub-area selected from a plurality of current sub-areas by a current eigenvalue sequence obtained by a eigenfunction, and the plurality of current sub-areas are obtained by dividing the previous sub-areas by the current iteration step size. The current search area updated by one iteration is cut out, and the three-dimensional coordinates of the positions of several current sub-areas are obtained until the preset iteration termination condition is reached. The position of the optimal sub-area screened out is the position of the underwater non-cooperative target, wherein the current eigenvalue sequence obtained by the characteristic function: the acoustic signal emitted by the underwater non-cooperative target is obtained in real time by the underwater monitoring component, and the moment when the acoustic signal arrives at each measuring unit is extracted. At the same time, the current three-dimensional coordinates of the position of each measuring unit when the acoustic signal arrives at each measuring unit are obtained by the above-water monitoring component; the underwater monitoring component measures the underwater sound speed of the estimated search area, and the moment when the acoustic signal arrives at each measuring unit, the current three-dimensional coordinates of the position of each measuring unit, the three-dimensional coordinates of the position of several current sub-areas and the underwater sound speed are input as parameters into the characteristic function to obtain the current eigenvalue sequence.

[0007] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0008] The estimated search area of ​​underwater non-cooperative targets is obtained, and a distributed long baseline measurement system is deployed based on the estimated search area to achieve multi-point positioning, reduce geometric constraint problems, and improve positioning accuracy. The robustness can be improved through redundant data and fault-tolerant mechanisms to ensure the continuity and reliability of the positioning function, and unnecessary resource consumption can be reduced through efficient search to reduce overall costs. Based on the domain iterative search strategy, the search range is narrowed by iteratively updating the current search area within the estimated search area until the preset iteration termination condition is reached. The location of the optimal sub-area selected is the location of the underwater non-cooperative target. The search range is gradually narrowed through the domain iterative search strategy, the amount of calculation is reduced, and the convergence speed can be improved to quickly converge to the vicinity of the target position, with high positioning accuracy and practicality.

[0009] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are specifically cited below. It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easy to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0011] Figure 1 A schematic diagram of a flow chart of a method for locating a non-cooperative target in water based on neighborhood iterative search according to an embodiment of the present application;

[0012] Figure 2 This is a structural diagram of an underwater non-cooperative target positioning system based on neighborhood iterative search in an embodiment of the present application;

[0013] Figure 3 A schematic diagram of the neighborhood iterative search process in an embodiment of the present application;

[0014] Figure 4 A schematic diagram of an estimated search area for underwater non-cooperative targets in an embodiment of the present application.

[0015] Description of reference numerals:

[0016] Distributed long baseline measurement system module 11, neighborhood iterative search module 12. DETAILED DESCRIPTION

[0017] The present application provides a method for locating non-cooperative targets in water based on neighborhood iterative search. By narrowing the search range through the neighborhood iterative search strategy, the positioning of non-cooperative targets in water can be searched more accurately and efficiently, thereby improving the efficiency of the search work and having strong practicality.

[0018] Below, the technical solutions in the present application will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments of the present application. It should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application. It should also be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, rather than all of them. Embodiment 1

[0019] The present application provides a method for locating non-cooperative targets in water based on neighborhood iterative search, and the method specifically comprises the following steps:

[0020] An estimated search area for underwater non-cooperative targets is obtained, and a distributed long baseline measurement system is deployed based on the estimated search area. The distributed long baseline measurement system includes a plurality of measurement units, and the monitoring unit includes a pair of underwater monitoring components and above-water monitoring components.

[0021] Specifically, the estimated search area of ​​underwater non-cooperative targets can be obtained by pre-judgment based on the movement law of underwater non-cooperative targets, or can be roughly measured by other measurement methods, or obtained based on historical information. According to the estimated search area, the distributed long baseline measurement system is deployed in the area to form a monitoring system that fully covers the area. The data provided by multiple nodes is used to achieve multi-point positioning of underwater non-cooperative targets and improve positioning accuracy. The long baseline can reduce geometric constraint problems and help reduce the impact of multipath effects. Because the difference in signal propagation paths is greater, it is easier to distinguish between direct signals and multipath signals, and it has strong robustness. The distributed long baseline measurement system includes several measurement units, which include paired underwater monitoring components and surface monitoring components. The underwater monitoring component is used to obtain the time difference between the acoustic signals emitted by underwater non-cooperative targets and the arrival of each measurement unit to achieve accurate positioning of the target. It can also be used as a part of the underwater communication network. Nodes can transmit data to each other to form an underwater communication network. Nodes can share information and work together to improve the overall performance of the system. It can also measure the underwater sound speed in the deployment area of ​​the distributed long baseline measurement system, that is, the estimated search area; the surface monitoring component can be connected to GPS or Beidou to obtain the location information of the measurement unit. A synchronization mechanism is provided to ensure that the underwater monitoring component obtains the acoustic signal while the surface monitoring obtains the three-dimensional coordinate information of the current position of the measurement unit. Synchronous acquisition of underwater information and surface information is very important for accurate positioning.

[0022] Based on the domain iterative search strategy, the search range is narrowed by iteratively updating the current search area in the estimated search area. The current search area is the optimal sub-area selected from a number of current sub-areas by the current feature value sequence obtained by the feature function. The several current sub-areas are cut according to the current iteration step size by the current search area updated in the previous iteration, and the three-dimensional coordinates of the positions of the several current sub-areas are obtained until the preset iteration termination condition is reached. The position of the selected optimal sub-area is the position of the underwater non-cooperative target.

[0023] Among them, the current eigenvalue sequence obtained by the characteristic function is:

[0024] Acquire the acoustic signal emitted by the underwater non-cooperative target in real time through the underwater monitoring component, extract the time when the acoustic signal arrives at each measurement unit, and at the same time, acquire the three-dimensional coordinates of the current position of each measurement unit when the acoustic signal arrives at each measurement unit through the above-water monitoring component;

[0025] The underwater monitoring component measures the estimated underwater sound speed in the search area, and inputs the time when the sound signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several current sub-areas and the underwater sound speed as parameters into the characteristic function to obtain the current characteristic value sequence.

[0026] Specifically, the domain iteration search strategy is a layer-by-layer refinement search method, which gradually approaches the target positioning by gradually narrowing the search range. Especially in the underwater non-cooperative target positioning application, it is within an iterative search framework, and the current iteration step is used to perform the task of narrowing the search range and iterative convergence. The current eigenvalue sequence of the characteristic function is used to screen several current sub-regions to obtain the optimal three-dimensional coordinates of the current sub-region. The sub-region corresponding to the optimal three-dimensional coordinates of the current sub-region is the current search region of the next iterative search. It is also a technical process for positioning using acoustic signals. The acoustic signals emitted by underwater non-cooperative targets are obtained in real time through underwater monitoring components, and the time t when the acoustic signals arrive at each measurement unit is extracted. i (i=1, 2, 3, ..., n), and at the same time, t is obtained through the water monitoring component i The current position P of each measurement unit at the moment i (x i ,y i ,z i ), (i=1, 2, 3, ..., n), obtain the three-dimensional coordinates of the positions of several current sub-areas, these coordinates of the current sub-areas are used for subsequent characteristic function calculations, and the underwater monitoring component measures the estimated sound speed C in the search area, and converts t i , P i (x i ,yi ,z i ), C and the three-dimensional coordinates of the positions of several current sub-regions are input as parameters into the feature function, and a result sequence is output, which is the result sequence of all current sub-regions, that is, the current eigenvalue sequence. The feature function is used to evaluate the possibility of sound sources in several current sub-regions. The maximum value is searched in the current eigenvalue sequence. The sub-region corresponding to the three-dimensional coordinates of the position of the sub-region corresponding to this maximum value is the current search region of the next iteration. When the preset iteration termination condition is reached, the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value are the positions of underwater non-cooperative targets. The maximum or minimum value in the search result sequence depends on the design purpose of the feature function.

[0027] Further, if Figure 1 As shown in the figure, the location of the selected optimal sub-area is the location of the underwater non-cooperative target, including:

[0028] S1; obtain the estimated search area Π1 of the underwater non-cooperative target;

[0029] S2: cutting the estimated search area Π1 into several sub-areas according to the initial step size, and obtaining the three-dimensional coordinates of the positions of the several sub-areas of Π1;

[0030] S3: Input the time when the acoustic signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π1 and the speed of sound in water as parameters into the characteristic function, obtain the Π1 eigenvalue sequence, search for the maximum value therein, obtain the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and complete the first iteration;

[0031] S4: taking the sub-region corresponding to the three-dimensional coordinates obtained in the first iteration as the current search region Π2, cutting the current search region Π2 into several sub-regions according to the current iteration step, obtaining the three-dimensional coordinates of the positions of several sub-regions of Π2, inputting the time when the acoustic signal arrives at each measurement unit, the current three-dimensional coordinates of the position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π2 and the sound speed in water as parameters into the characteristic function, obtaining the Π2 eigenvalue sequence, searching for the maximum value therefrom, obtaining the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and completing the second iteration;

[0032] S5: Repeat S4 until the current iteration step meets the preset iteration termination condition, and use the sub-region corresponding to the three-dimensional coordinates obtained in the previous iteration as the current search region Π q , Π q The three-dimensional coordinates of the position of the sub-region corresponding to the maximum value in the eigenvalue sequence are the positions of the underwater non-cooperative targets. The qth iteration is completed and the iteration is terminated.

[0033] Specifically, in the first iteration, the estimated search area Π1 is cut according to the initial step size θ1: sub-regions, the coordinates of each sub-region are P 01_i (x 01_i ,y 01_i ,z 01_i ), 01_i=1,2,..., . i、 P i (x i ,y i ,z i ), C, P 01_i (x 01_i ,y 01_i ,z 01_i ) is substituted into the characteristic function, and the resulting sequence is D 01_i (x 01_i ,y 01_i ,z 01_i ), and search for the maximum value D 01_m , D 01_m The position coordinates of the corresponding sub-region are P 01_m (x 01_m ,y 01_m ,z 01_m ).

[0034] Iteration 2: P 01_m (x 01_m ,y 01_m ,z 01_m ) is used as the target area, and the cutting area Π2 is obtained according to the current iteration step θ2 (θ2 < θ1). sub-regions, and the position coordinates of each sub-region are

[0035] P 02_i (x 02_i ,y 02_i ,z 02_i ), 02_i=1,2,..., . i、 P i (x i ,y i ,z i ), C, P 02_i (x 02_i ,y 02_i ,z 02_i ) is substituted into the characteristic function, and the resulting sequence is D 02_i (x 02_i ,y 02_i ,z 02_i ), and search for the maximum value D 02_m , D 02_m The position coordinates of the corresponding sub-region are P 02_m (x 02_m,y 02_m ,z 02_m ).

[0036] Repeat the above iterative process until the current step length θ q This is equivalent to the positioning resolution requirement for underwater non-cooperative targets. 0q_m The position coordinates of the corresponding sub-region are P 0q_m (x 0q_m ,y 0q_m ,z 0q_m ), which is the positioning result of the underwater non-cooperative target. The three-dimensional coordinates of the positions of several sub-regions can be represented by the coordinates of the geometric center of each sub-region, or by the coordinates of specific points selected on the boundaries of each sub-region, or can be calculated in a certain weighted manner within the region.

[0037] Furthermore, the current iteration step size satisfies the preset iteration termination conditions, including:

[0038] Preset underwater non-cooperative target positioning resolution, where the positioning resolution is the minimum resolvable distance that can be achieved;

[0039] Acquire the estimated search area size, the initial step size corresponds to the estimated search area size, and perform the first iterative cutting;

[0040] Obtaining the iteratively updated current search area size, wherein the current iteration step size corresponds to the current search area size, and performing iterative cutting;

[0041] When the current iteration step meets the preset underwater non-cooperative target positioning resolution, the iterative cutting stops. Specifically, the positioning resolution is the minimum resolvable distance that can be achieved, including meters, centimeters, seconds, arc seconds, etc. In the domain iterative search strategy, the iteration step is set to perform the task of gradually refining the search area. The iteration step selection corresponds to the size of the iteration area, which means that the step selection will be dynamically adjusted according to the size of the current search area, obtain the estimated search area size, preset a fixed adjustment ratio (such as 10%) and an initial step, the initial step is based on a certain ratio of the estimated search area side length (such as 1 / 5, 1 / 10, etc.), and perform the first iterative cutting; obtain the iteratively updated current search area size, adjust the current iteration step according to the current search area size and the preset fixed adjustment ratio, and perform iterative cutting. The preset fixed adjustment ratio is set based on historical experience and understanding of the characteristics of the search area. The current iteration step can be a uniform step or a non-uniform step.

[0042] like Figure 3 In the embodiment shown, the positioning resolution is agreed to be meter level, the iteration termination condition is that the step length is 1m, and a uniform step length is selected to cut the area;

[0043] In the first iteration, the size of area Π1 is several kilometers, and the step size 1 is 100m;

[0044] The size of the second iteration area Π2 is 100m, and the step size 2 is 10m;

[0045] The size of the third iteration region Π3 is 10m, and the step length 3 is 1m. At this time, the step length reaches the iteration termination condition, and the position coordinates of the sub-region corresponding to the maximum value P 03_m (x 03_m ,y 03_m ,z 03_m ) is the estimated position of the underwater non-cooperative target .

[0046] Furthermore, the characteristic functions include:

[0047] Based on the isotropy of the water medium in the estimated search area, according to the time t at which the acoustic signal reaches each measuring unit i and the speed of sound in water C, calculate the time t at which the acoustic signal arrives at each measuring unit i The current distance A from the current position of each measurement unit to the underwater non-cooperative target i ,

[0048] A i = C ( t i - t ) (1)

[0049] Where t is the time when the underwater non-cooperative target transmits the acoustic signal;

[0050] According to the three-dimensional coordinates of the current position of each measuring unit, the time t at which the acoustic signal arrives at each measuring unit can be listed. i The current distance formula from the current position of each measurement unit to the underwater non-cooperative target is: (2)

[0051] in, is the time t when the sound signal arrives at each measurement unit i The current distance from the current position of each measurement unit to the underwater non-cooperative target, is the three-dimensional coordinate of the current position of each measurement unit, The location of the underwater non-cooperative target to be determined;

[0052] From formula (1), we can get

[0053] , (i,j=(1,2,...,k), i ≠ j) (3)

[0054] From equations (1) and (2), we can conclude that

[0055] (i=1, 2, ..., n) (4)

[0056] From equations (3) and (4), we can conclude that

[0057] , (i,j=(1,2,...,k), i ≠ j) (5)

[0058] According to the actual experience of underwater acoustic positioning, it is found that there is an error between the time when the measurement sound signal arrives at each measurement unit and the current position of each measurement unit, that is, If is not 0, the characteristic function is:

[0059] , (i,j=(1,2,...,k), i ≠ j) (6)

[0060] Here, n is the number of measurement units.

[0061] Specifically, the estimated search area of ​​underwater non-cooperative targets is the distributed long baseline measurement system, which is also the initial area of ​​neighborhood iteration. Figure 4 As shown in the three-dimensional rectangular coordinate system, the estimated search area of ​​underwater non-cooperative targets is defined as Π1[Xϵ(x a ,x b ),Yϵ(y a ,y b ),Zϵ(z a ,z b )], where x a is the minimum value of the X component corresponding to Π1 in the coordinate system, x b is the maximum value of the corresponding X component, y a Corresponding to the minimum value of the Y component, y b Corresponding to the maximum value of the Y component, z a Corresponding to the minimum value of the Z component, z b The corresponding maximum value of the Z component. A distributed long baseline measurement system is deployed in Π1, with a total of n (n≥4) measurement units. The underwater monitoring component measures the speed of sound in water as C. The underwater non-cooperative target emits an acoustic signal. The underwater monitoring component obtains the acoustic signal emitted by the underwater non-cooperative target in real time and extracts the time t when the acoustic signal arrives at each measurement unit. i (i=1, 2, 3, ..., n), at the same time, the current position P of each measurement unit i (x i ,y i ,z i ), (i=1, 2, 3, ..., n). Assuming that the water medium in region Π1 is isotropic, we can know that:

[0062] The time when the sound signal reaches each measuring unit The current distance from the current position of each monitoring unit to the underwater non-cooperative target ,

[0063] A i = C ( t i - t ) (1)

[0064] Where t is the time when the underwater non-cooperative target transmits the acoustic signal;

[0065] According to the three-dimensional coordinates of the current position of each measurement unit, the current distance formula from the current position of each measurement unit to the non-cooperative target can be listed.

[0066] (2)

[0067] in, is the time t when the sound signal arrives at each measurement unit i The current distance from the current position of each measurement unit to the underwater non-cooperative target, is the three-dimensional coordinate of the current position of each measurement unit, The location of the underwater non-cooperative target to be determined;

[0068] From formula (1), we can get

[0069] , (i,j=(1,2,...,k), i ≠ j) (3)

[0070] In theory,

[0071] (i=1, 2, ..., n) (4)

[0072] In order to eliminate the unknown quantity t, the following set of equations can be listed from equations (3) and (4):

[0073] , (i,j=(1,2,...,k), i ≠ j) (5)

[0074] In actual underwater acoustic positioning, the time when the measured sound signal reaches each measurement unit is affected by various factors. and the current position of each measurement unit There must be errors, that is, If is not 0, the characteristic function is:

[0075] , (i,j=(1,2,...,k), i ≠ j) (6)

[0076] Here, n is the number of measurement units.

[0077] If we create a neighborhood of the position P(x, y, z) where the underwater non-cooperative target is located:

[0078]

[0079] When the position estimate It is exactly at the actual location of the underwater non-cooperative target, that is, When , it is obvious that formula (6) takes the minimum value, that is, the time when the sound signal arrives at each measurement unit, the current three-dimensional coordinates of each measurement unit, the three-dimensional coordinates of the positions of several current sub-regions and the speed of sound in water are input as parameters into the characteristic function formula (6), and the current eigenvalue sequence is output. The minimum value is searched from it to obtain the three-dimensional coordinates of the position of the current sub-region corresponding to the minimum value.

[0080] In summary, the embodiment of the present application provides a method for locating non-cooperative targets in water based on iterative neighborhood search, which has the following technical effects:

[0081] 1) By deploying a distributed long baseline measurement system to cover the estimated search area of ​​underwater non-cooperative targets, multi-point positioning can be achieved, geometric constraints can be reduced, positioning accuracy can be improved, and the redundancy and fault tolerance mechanism of the system can improve robustness, ensure the continuity and reliability of the positioning function, and improve search efficiency;

[0082] 2) The search range is gradually narrowed according to the neighborhood iterative search strategy. The principle is simple, the calculation amount is small, the robustness and practicality are strong, and it is more suitable for application in real-time systems and embedded systems.

[0083] Based on the same inventive concept as the method for locating a non-cooperative target in water based on neighborhood iterative search in the aforementioned embodiment, Figure 2 As shown, an embodiment of the present application provides an underwater non-cooperative target positioning system based on neighborhood iterative search, and the system includes:

[0084] A distributed long baseline measurement system module 11, the distributed long baseline measurement system module 11 is used to obtain an estimated search area for underwater non-cooperative targets, and deploy a distributed long baseline measurement system based on the estimated search area. The distributed long baseline measurement system includes a plurality of measurement units, and the measurement units include a pair of underwater monitoring components and above-water monitoring components;

[0085] A neighborhood iterative search module 12, the domain iterative search module 12 is used to narrow the search range by iteratively updating the current search area within the estimated search area based on a domain iterative search strategy, the current search area is an optimal sub-area selected from a number of current sub-areas by a current feature value sequence obtained by a feature function, the several current sub-areas are cut according to the current iteration step length by the current search area updated in the previous iteration, and the three-dimensional coordinates of the positions of the several current sub-areas are obtained until a preset iteration termination condition is reached, and the position of the selected optimal sub-area is the position of the underwater non-cooperative target,

[0086] Among them, the current eigenvalue sequence obtained by the characteristic function is:

[0087] Acquire the acoustic signal emitted by the underwater non-cooperative target in real time through the underwater monitoring component, extract the time when the acoustic signal arrives at each measurement unit, and at the same time, acquire the three-dimensional coordinates of the current position of each measurement unit when the acoustic signal arrives at each measurement unit through the above-water monitoring component;

[0088] The underwater monitoring component measures the estimated underwater sound speed in the search area, and inputs the time when the sound signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several current sub-areas and the underwater sound speed as parameters into the characteristic function to obtain the current characteristic value sequence.

[0089] Furthermore, the system also includes an underwater non-cooperative target positioning module to perform the following operation steps:

[0090] S1; obtain the estimated search area Π1 of the underwater non-cooperative target;

[0091] S2: cutting the estimated search area Π1 into several sub-areas according to the initial step size, and obtaining the three-dimensional coordinates of the positions of the several sub-areas of Π1;

[0092] S3: Input the time when the acoustic signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π1 and the speed of sound in water as parameters into the characteristic function, obtain the Π1 eigenvalue sequence, search for the maximum value therein, obtain the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and complete the first iteration;

[0093] S4: taking the sub-region corresponding to the three-dimensional coordinates obtained in the first iteration as the current search region Π2, cutting the current search region Π2 into several sub-regions according to the current iteration step, obtaining the three-dimensional coordinates of the positions of several sub-regions of Π2, inputting the time when the acoustic signal arrives at each measurement unit, the current three-dimensional coordinates of the position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π2 and the sound speed in water as parameters into the characteristic function, obtaining the Π2 eigenvalue sequence, searching for the maximum value therefrom, obtaining the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and completing the second iteration;

[0094] S5: Repeat S4 until the current iteration step meets the preset iteration termination condition, and use the sub-region corresponding to the three-dimensional coordinates obtained in the previous iteration as the current search region Π q , Π q The three-dimensional coordinates of the position of the sub-region corresponding to the maximum value in the eigenvalue sequence are the positions of the underwater non-cooperative targets. The qth iteration is completed and the iteration is terminated.

[0095] Furthermore, the system also includes a current iteration step module to perform the following operation steps:

[0096] Preset underwater non-cooperative target positioning resolution, where the positioning resolution is the minimum resolvable distance that can be achieved;

[0097] Acquire the estimated search area size, the initial step size corresponds to the estimated search area size, and perform the first iterative cutting;

[0098] Obtaining the iteratively updated current search area size, wherein the current iteration step size corresponds to the current search area size, and performing iterative cutting;

[0099] When the current iteration step size meets the preset underwater non-cooperative target positioning resolution, the iterative cutting stops.

[0100] Furthermore, the system also includes a characteristic function module to perform the following operation steps:

[0101] Based on the isotropy of the water medium in the estimated search area, according to the time t at which the acoustic signal reaches each measuring unit i and the speed of sound in water C, calculate the time t at which the acoustic signal arrives at each measuring unit i The current distance A from the current position of each measurement unit to the underwater non-cooperative target i ,

[0102] A i = C ( t i - t ) (1)

[0103] Where t is the time when the underwater non-cooperative target transmits the acoustic signal;

[0104] According to the three-dimensional coordinates of the current position of each measuring unit, the time t at which the acoustic signal arrives at each measuring unit can be listed. i The current distance formula from the current position of each measurement unit to the underwater non-cooperative target is: (2)

[0105] in, is the time t when the sound signal arrives at each measurement unit i The current distance from the current position of each measurement unit to the underwater non-cooperative target, is the three-dimensional coordinate of the current position of each measurement unit, The location of the underwater non-cooperative target to be determined;

[0106] From formula (1), we can get

[0107] , (i,j=(1,2,...,k), i ≠ j) (3)

[0108] From equations (1) and (2), we can conclude that

[0109] (i=1, 2, ..., n) (4)

[0110] From equations (3) and (4), we can conclude that

[0111] , (i,j=(1,2,...,k), i ≠ j) (5)

[0112] According to the actual experience of underwater acoustic positioning, it is found that there is an error between the time when the measurement sound signal arrives at each measurement unit and the current position of each measurement unit, that is, If is not 0, the characteristic function is: , (i,j=(1,2,...,k), i ≠ j) (6)

[0113] Here, n is the number of measurement units.

[0114] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for locating non-cooperative targets in water based on neighborhood iterative search, characterized in that: The method comprises: Obtain an estimated search area for underwater non-cooperative targets, and deploy a distributed long baseline measurement system based on the estimated search area, wherein the distributed long baseline measurement system includes a plurality of measurement units, and the measurement units include a pair of underwater monitoring components and surface monitoring components; Based on the neighborhood iterative search strategy, the search range is narrowed by iteratively updating the current search area in the estimated search area, the current search area is the optimal sub-area selected from a number of current sub-areas by the current feature value sequence obtained by the feature function, the several current sub-areas are cut according to the current iteration step size by the current search area updated in the previous iteration, and the three-dimensional coordinates of the positions of the several current sub-areas are obtained until the preset iteration termination condition is reached, and the position of the selected optimal sub-area is the position of the underwater non-cooperative target, Among them, the current eigenvalue sequence obtained by the characteristic function is: Acquire the acoustic signal emitted by the underwater non-cooperative target in real time through the underwater monitoring component, extract the time when the acoustic signal arrives at each measurement unit, and at the same time, acquire the three-dimensional coordinates of the current position of each measurement unit when the acoustic signal arrives at each measurement unit through the above-water monitoring component; The underwater monitoring component measures the estimated underwater sound speed in the search area, and inputs the time when the sound signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several current sub-areas and the underwater sound speed as parameters into the characteristic function to obtain the current characteristic value sequence.

2. The non-cooperative target positioning method in water based on neighborhood iterative search as claimed in claim 1, The characteristic is that The location of the selected optimal sub-area is the location of the underwater non-cooperative target, including: S1; obtain the estimated search area Π1 of the underwater non-cooperative target; S2: cutting the estimated search area Π1 into several sub-areas according to the initial step size, and obtaining the three-dimensional coordinates of the positions of the several sub-areas of Π1; S3: Input the time when the acoustic signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π1 and the speed of sound in water as parameters into the characteristic function, obtain the Π1 eigenvalue sequence, search for the maximum value therein, obtain the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and complete the first iteration; S4: taking the sub-region corresponding to the three-dimensional coordinates obtained in the first iteration as the current search region Π2, cutting the current search region Π2 into several sub-regions according to the current iteration step, obtaining the three-dimensional coordinates of the positions of several sub-regions of Π2, inputting the time when the acoustic signal arrives at each measurement unit, the current three-dimensional coordinates of the position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π2 and the sound speed in water as parameters into the characteristic function, obtaining the Π2 eigenvalue sequence, searching for the maximum value therefrom, obtaining the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and completing the second iteration; S5: Repeat S4 until the current iteration step meets the preset iteration termination condition, and use the sub-region corresponding to the three-dimensional coordinates obtained in the previous iteration as the current search region Π q , Π q The three-dimensional coordinates of the position of the sub-region corresponding to the maximum value in the eigenvalue sequence are the positions of the underwater non-cooperative targets. The qth iteration is completed and the iteration is terminated.

3. The non-cooperative target positioning method in water based on neighborhood iterative search as claimed in claim 2, The characteristic is that The current iteration step size satisfies a preset iteration termination condition, including: Preset underwater non-cooperative target positioning resolution, where the positioning resolution is the minimum resolvable distance that can be achieved; Acquire the estimated search area size, the initial step size corresponds to the estimated search area size, and perform the first iterative cutting; Obtaining the iteratively updated current search area size, wherein the current iteration step size corresponds to the current search area size, and performing iterative cutting; When the current iteration step size meets the preset underwater non-cooperative target positioning resolution, the iterative cutting stops.

4. The method for locating non-cooperative targets in water based on neighborhood iterative search as claimed in claim 1, characterized in that: The characteristic function includes: Based on the isotropy of the water medium in the estimated search area, according to the time t at which the acoustic signal reaches each measuring unit i and the speed of sound in water C, calculate the time t at which the acoustic signal arrives at each measuring unit i The current distance A from the current position of each measurement unit to the underwater non-cooperative target i , A i = C ( t i - t ) (1) Where t is the time when the underwater non-cooperative target transmits the acoustic signal; According to the three-dimensional coordinates of the current position of each measuring unit, the time t at which the acoustic signal arrives at each measuring unit can be listed. i The current distance formula from the current position of each measurement unit to the underwater non-cooperative target is: （2） in, is the time t when the sound signal arrives at each measurement unit i The current distance from the current position of each measurement unit to the underwater non-cooperative target, is the three-dimensional coordinate of the current position of each measurement unit, (x, y, z) is the position of the underwater non-cooperative target to be determined; From formula (1), we can get （3） From equations (1) and (2), we can conclude that （4） From equations (3) and (4), we can conclude that （5） According to the actual experience of underwater acoustic positioning, it is found that there is an error between the time when the measurement sound signal arrives at each measurement unit and the current position of each measurement unit, that is, is not 0, then the characteristic function is: （6） Here, n is the number of measurement units.

5. A non-cooperative target positioning system in water based on neighborhood iterative search, characterized in that: Said The system is applied to any one of claims 1 to 4, comprising: A distributed long baseline measurement system module, the distributed long baseline measurement system module is used to obtain an estimated search area for underwater non-cooperative targets, and deploy a distributed long baseline measurement system based on the estimated search area. The distributed long baseline measurement system includes a plurality of measurement units, and the measurement units include a pair of underwater monitoring components and above-water monitoring components; A neighborhood iterative search module, the neighborhood iterative search module is used to narrow the search range by iteratively updating the current search area within the estimated search area based on the neighborhood iterative search strategy, the current search area is the optimal sub-area selected from a number of current sub-areas by the current feature value sequence obtained by the feature function, the several current sub-areas are cut according to the current iteration step size by the current search area updated in the previous iteration, and the three-dimensional coordinates of the positions of the several current sub-areas are obtained until the preset iteration termination condition is reached, and the position of the selected optimal sub-area is the position of the underwater non-cooperative target, Among them, the current eigenvalue sequence obtained by the characteristic function is: Acquire the acoustic signal emitted by the underwater non-cooperative target in real time through the underwater monitoring component, extract the time when the acoustic signal arrives at each measurement unit, and at the same time, acquire the three-dimensional coordinates of the current position of each measurement unit when the acoustic signal arrives at each measurement unit through the above-water monitoring component; The underwater monitoring component measures the estimated underwater sound speed in the search area, and inputs the time when the sound signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several current sub-areas and the underwater sound speed as parameters into the characteristic function to obtain the current characteristic value sequence.

6. The non-cooperative target positioning system in water based on neighborhood iterative search as claimed in claim 5, The characteristic is that It also includes a non-cooperative underwater target positioning module to perform the following steps: S1; obtain the estimated search area Π1 of the underwater non-cooperative target; S2: cutting the estimated search area Π1 into several sub-areas according to the initial step size, and obtaining the three-dimensional coordinates of the positions of the several sub-areas of Π1; S3: Input the time when the acoustic signal arrives at each measurement unit, the three-dimensional coordinates of the current position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π1 and the speed of sound in water as parameters into the characteristic function, obtain the Π1 eigenvalue sequence, search for the maximum value therein, obtain the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and complete the first iteration; S4: taking the sub-region corresponding to the three-dimensional coordinates obtained in the first iteration as the current search region Π2, cutting the current search region Π2 into several sub-regions according to the current iteration step, obtaining the three-dimensional coordinates of the positions of several sub-regions of Π2, inputting the time when the acoustic signal arrives at each measurement unit, the current three-dimensional coordinates of the position of each measurement unit, the three-dimensional coordinates of the positions of several sub-regions of Π2 and the sound speed in water as parameters into the characteristic function, obtaining the Π2 eigenvalue sequence, searching for the maximum value therefrom, obtaining the three-dimensional coordinates of the position of the sub-region corresponding to the maximum value, and completing the second iteration; S5: Repeat S4 until the current iteration step meets the preset iteration termination condition, and use the sub-region corresponding to the three-dimensional coordinates obtained in the previous iteration as the current search region Π q , Π q The three-dimensional coordinates of the position of the sub-region corresponding to the maximum value in the eigenvalue sequence are the positions of the underwater non-cooperative targets. The qth iteration is completed and the iteration is terminated.

7. The underwater non-cooperative target positioning system based on neighborhood iterative search as claimed in claim 6, It is characterized in that The current iteration step module is also included to perform the following steps: Preset underwater non-cooperative target positioning resolution, where the positioning resolution is the minimum resolvable distance that can be achieved; Acquire the estimated search area size, the initial step size corresponds to the estimated search area size, and perform the first iterative cutting; Obtaining the iteratively updated current search area size, wherein the current iteration step size corresponds to the current search area size, and performing iterative cutting; When the current iteration step size meets the preset underwater non-cooperative target positioning resolution, the iterative cutting stops.

8. The underwater non-cooperative target positioning system based on neighborhood iterative search as claimed in claim 5, It is characterized in that It also includes a feature function module to perform the following steps: Based on the isotropy of the water medium in the estimated search area, according to the time t at which the acoustic signal reaches each measuring unit i and the speed of sound in water C, calculate the time t at which the acoustic signal arrives at each measuring unit i The current distance A from the current position of each measurement unit to the underwater non-cooperative target i , A i = C ( t i - t ) (1) Where t is the time when the underwater non-cooperative target transmits the acoustic signal; According to the three-dimensional coordinates of the current position of each measuring unit, the time t at which the acoustic signal arrives at each measuring unit can be listed. i The current distance formula from the current position of each measurement unit to the underwater non-cooperative target is: （2） in, is the time t when the sound signal arrives at each measurement unit i The current distance from the current position of each measurement unit to the underwater non-cooperative target, is the three-dimensional coordinate of the current position of each measurement unit, (x, y, z) is the position of the underwater non-cooperative target to be determined; From formula (1), we can get （3） From equations (1) and (2), we can conclude that （4） From equations (3) and (4), we can conclude that （5） According to the actual experience of underwater acoustic positioning, it is found that there is an error between the time when the measurement sound signal arrives at each measurement unit and the current position of each measurement unit, that is, is not 0, then the characteristic function is: （6） Here, n is the number of measurement units.

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