Ultra-short baseline positioning method and system based on TDOA observation value and effective sound speed

Abstract

The present application relates to the technical field of ultra-short baseline positioning, and particularly relates to an ultra-short baseline positioning method and system based on TDOA observation values and effective sound velocity, a spatial geometric distance mathematical relationship between a hydrophone and a sound source target is constructed according to a position vector of the hydrophone in a carrier coordinate system in a USBL system, and an ultra-short baseline TDOA observation equation is established, unknown parameters of the ultra-short baseline TDOA observation equation include an effective sound velocity parameter and a sound source position vector parameter; an effective sound velocity approximation value and a sound source position vector approximation value are brought into the ultra-short baseline TDOA observation equation to linearize the ultra-short baseline TDOA observation equation; the linearized ultra-short baseline TDOA observation equation is solved iteratively by using a least square method criterion, and final effective sound velocity and a sound source target position vector are obtained according to a solution result. The present application can be applied to a USBL system taking TDOA as original observation values, can avoid sound ray bending influence, has simple calculation principles, and can be embedded for use in a new type of USBL positioning system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-short baseline positioning, in particular to an ultra-short baseline positioning method and system based on TDOA observation value and effective sound speed. BACKGROUND

[0002] A conventional ultra-short baseline positioning system contains two types of observation values: time difference of arrival (TDOA) of acoustic signals and propagation time delay. The time difference of arrival is used to determine the direction of the sound source, and the propagation time delay is used to determine the distance of the sound source, and then the position of the sound source is determined through the direction and the distance. Obviously, the traditional USBL positioning technology will be affected by the sound ray bending, and the obtained sound source direction is actually the direction of arrival of the sound wave at the receiving array, rather than the real sound source direction. Moreover, an accurate effective sound speed is needed to accurately calculate the Euclidean distance from the sound source to the USBL base array by using the propagation time delay of the acoustic signal. However, the effective sound speed cannot be accurately obtained. The existing method uses the average sound speed instead of the effective sound speed, which is not accurate. The existing method uses sound ray tracking correction to calculate the Euclidean distance, which requires the sound speed profile of the working water area to be determined, which increases the workload of the outside field and reduces the working efficiency of the USBL system. SUMMARY

[0003] Therefore, the present application provides an ultra-short baseline positioning method and system based on TDOA observation value and effective sound speed, which solves the problem of the influence of sound ray bending and unknown effective sound speed on the positioning result in the existing ultra-short baseline positioning.

[0004] According to the design scheme provided by the present application, on the one hand, an ultra-short baseline positioning method based on TDOA observation value and effective sound speed is provided, which comprises:

[0005] A spatial geometric distance mathematical relationship between the hydrophone and the sound source target is constructed according to the position vector of the hydrophone in the carrier coordinate system in the USBL system, and an ultra-short baseline TDOA observation equation is established. The unknown parameters of the ultra-short baseline TDOA observation equation include the effective sound speed parameter and the sound source position vector parameter.

[0006] An approximate value of the effective sound speed and an approximate value of the sound source position vector are obtained, and the approximate value of the effective sound speed and the approximate value of the sound source position vector are brought into the ultra-short baseline TDOA observation equation to linearize the ultra-short baseline TDOA observation equation.

[0007] The linearized ultra-short baseline TDOA observation equation is solved by using the least square method criterion, and the final effective sound speed and sound source target position vector are obtained according to the solving result.

[0008] As the ultra-short baseline positioning method based on TDOA observation value and effective sound speed of the present application, further, the spatial geometric distance mathematical relationship between the hydrophone and the sound source target comprises:

[0009] a distance representing a sound signal propagation time delay based on a sound signal emission time, a hydrophone sound signal reception time and an effective sound speed;

[0010] a spatial geometric distance mathematical relationship between the hydrophone and the sound source is established using the sound signal propagation time delay distance and based on position vectors of the hydrophone and the sound source in a carrier coordinate system.

[0011] As the present application, the super short baseline positioning method based on TDOA observation value and effective sound speed, further, the spatial geometric distance mathematical relationship is expressed as: p i = (p T p-2p T p i +p i T p i 1 / 2 , wherein p i is a sound signal propagation time delay distance, and p i = c eff (t i -t0), c eff is an effective sound speed, t0 is a sound signal emission time, t i is a time when the hydrophone i receives the sound signal, p i and p are position vectors of the hydrophone and the sound source in a carrier coordinate system, respectively.

[0012] As the present application, the super short baseline positioning method based on TDOA observation value and effective sound speed, further, the super short baseline TDOA observation equation is established, including:

[0013] The effective sound speed and the sound source position vector are taken as unknown parameters, and the super short baseline TDOA observation equation is constructed based on the spatial geometric distance mathematical relationship and using the known position vector of the hydrophone in the carrier coordinate system.

[0014] As the present application, the super short baseline positioning method based on TDOA observation value and effective sound speed, further, the super short baseline TDOA observation equation is expressed as: Δt ij is a TDOA observation value between the super short baseline hydrophone j and the hydrophone i, P is a sound source position vector, c eff is an effective sound speed, p i and p j are position vectors of the known hydrophone i and the hydrophone j in the carrier coordinate system, respectively.

[0015] As the present application, the super short baseline positioning method based on TDOA observation value and effective sound speed, further, the effective sound speed approximation value and the sound source position vector approximation value are obtained, including:

[0016] ​The average sound speed or the specified sound speed is taken as an approximation of the effective sound speed, and the sound source position vector approximation is determined based on the TDOA and the propagation time delay of the sound signal and the sound source direction and the sound source distance.

[0017] As the USBL positioning method based on the TDOA observation value and the effective sound speed of the application, further, the linearized USBL TDOA observation equation is solved iteratively by using the least square method criterion, which contains:

[0018] The position vector of the known hydrophone in the carrier coordinate system and the unknown parameters are used to represent the coefficient matrix and the free term of the least square error equation;

[0019] Based on the coefficient matrix, the free term and the unknown parameters, the observation equation iterative solution model is constructed, and the model is iteratively solved by updating the unknown parameter approximation until the unknown parameter reaches the stable condition.

[0020] In another aspect, the application also provides a USBL positioning system based on the TDOA observation value and the effective sound speed, which contains an observation equation construction module, an observation equation linearization module and a least square solution module, wherein,

[0021] The observation equation construction module is used to construct the spatial geometric distance mathematical relationship between the hydrophone and the sound source target according to the position vector of the hydrophone in the carrier coordinate system in the USBL system, and to establish the USBL TDOA observation equation, the unknown parameters of the USBL TDOA observation equation including the effective sound speed parameter and the sound source position vector parameter;

[0022] The observation equation linearization module is used to linearize the USBL TDOA observation equation by obtaining the effective sound speed approximation and the sound source position vector approximation, and bringing the effective sound speed approximation and the sound source position vector approximation into the USBL TDOA observation equation;

[0023] The least square solution module is used to solve the linearized USBL TDOA observation equation iteratively by using the least square method criterion, and to obtain the final effective sound speed and the sound source target position vector according to the solution result.

[0024] The application has the following beneficial effects:

[0025] The application establishes an observation equation of TDOA observation value by using effective sound speed, and takes the effective sound speed and the sound source position parameter as unknown parameters, and then solves the effective sound speed and the sound source position parameter by using a nonlinear least square method, can be applied to the USBL system taking TDOA as the original observation value, does not need the propagation time delay, does not need to measure the sound speed profile, and does not need to provide the effective sound speed information, can complete the underwater target positioning and the effective sound speed calculation by using not less than four TDOA observation values, can avoid the influence of sound ray bending, the calculation principle is simple, can be embedded in the new USBL positioning system, and is helpful to improve the USBL system design, and has good application prospect in the ultra-short baseline positioning field. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a schematic diagram of the ultra-short baseline positioning process based on the TDOA observation value and the effective sound speed in the embodiment.

[0027] Figure 2 The figure is a schematic diagram of the spatial position relationship between the hydrophone and the sound source in the embodiment. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the application more clear and explicit, the application will be further described in detail below with reference to the drawings and technical scheme.

[0029] Since the receiving array in the USBL system is very small, the distance between the hydrophones is usually less than half a wavelength, that is, the distance between the hydrophones is much smaller than the distance between the sound source and itself. Therefore, the sound signal propagation paths from the sound source to each hydrophone are theoretically very similar, that is, the effective sound speed corresponding to each sound ray is the same. The embodiment of the application, as shown in the figure, provides an ultra-short baseline positioning method based on TDOA observation value and effective sound speed, which comprises: Figure 1

[0030] S101, constructing the spatial geometric distance mathematical relationship between the hydrophone and the sound source target according to the position vector of the hydrophone in the carrier coordinate system, and establishing an ultra-short baseline TDOA observation equation, wherein the unknown parameters of the ultra-short baseline TDOA observation equation include the effective sound speed parameter and the sound source position vector parameter.

[0031] Specifically, the spatial geometric distance mathematical relationship between the hydrophone and the sound source target can be designed to include:

[0032] The distance based on the sound signal emission time, the hydrophone sound signal receiving time and the effective sound speed to represent the sound signal propagation time delay;

[0033] ​The distance between the hydrophone and the sound source is calculated by the time delay of the acoustic signal propagation and based on the position vectors of the hydrophone and the sound source in the carrier coordinate system.

[0034] As shown in Figure 2 , let the position vector of the hydrophone i in the carrier coordinate system be p i , and the position vector of the sound source be p, then the spatial geometric distance between the hydrophone and the sound source is ||pp i ||(||·|| represents the modulus operation), and the following mathematical relationship is established:

[0035] ρ i =(p T p-2p T p i +p i T p i ) 1 / 2 (1)

[0036] In the formula, ρ i =c eff (t i -t0) is the distance calculated by the time delay of the acoustic signal propagation, c eff is the effective sound speed (defined as the ratio of the Euclidean distance between the sound source and the receiving point to the intrinsic sound line propagation time), t0 is the time when the acoustic signal is transmitted, and t i is the time when the hydrophone i receives the acoustic signal.

[0037] The effective sound speed and the position vector of the sound source are taken as unknown parameters, and the spatial geometric distance mathematical relationship is used to construct the ultra-short baseline TDOA observation equation based on the known position vector of the hydrophone in the carrier coordinate system. The established TDOA observation equation can be expressed as:

[0038]

[0039] In the formula, Δt ij =t j -t i is the TDOA observation value of the ultra-short baseline; p=[x y z] T is the position vector of the sound source; p j =[x j y j z j ] T and p i =[x i y i z i ] T are the known position vectors of the hydrophone.

[0040] S102, obtain an effective sound speed approximation value and a sound source position vector approximation value, and bring the effective sound speed approximation value and the sound source position vector approximation value into the ultra-short baseline TDOA observation equation to linearize the ultra-short baseline TDOA observation equation.

[0041] Specifically, the average sound speed or the specified sound speed can be taken as the effective sound speed approximation value, and the sound source position vector approximation value is determined based on the TDOA and the propagation time delay of the sound signal and through the sound source direction and the sound source distance.

[0042] The specified sound speed value can be set to about 1500 m / s, and can be adjusted according to the actual scene. The sound source position vector approximation value can be calculated by using the existing conventional method.

[0043] S103, iteratively solve the linearized ultra-short baseline TDOA observation equation by using the least square method criterion, and obtain the final effective sound speed and the sound source target position vector according to the solving result.

[0044] Specifically, the linearized ultra-short baseline TDOA observation equation is iteratively solved by using the least square method criterion, which can include:

[0045] The position vector of the known hydrophone in the carrier coordinate system and the unknown parameter are used to represent the coefficient matrix and the free term of the least square error equation.

[0046] The coefficient matrix, the free term, and the unknown parameter are used to construct an observation equation iterative solving model, so as to iteratively solve the model by updating the unknown parameter approximation value until the unknown parameter reaches a stable condition.

[0047] The specific iterative solving process can be described as follows:

[0048] Both the sound source position and the effective sound speed are taken as unknown parameters, and are substituted into the parameter approximation value linearization observation equation:

[0049]

[0050] In the formula, p and c eff take their approximation values.

[0051] According to the least square principle, the optimal estimate value of the unknown parameter is calculated as follows:

[0052]

[0053] In the formula, is the approximation value of the unknown parameter; A is the coefficient matrix of the error equation, and l is the free term of the error equation, which are functions of the known hydrophone position vector and the unknown parameter approximation value. In the matrix A, the expression of the row vector is as follows:

[0054]

[0055] The expression of the elements in the free term I is as follows:

[0056]

[0057] where k = 1, 2, 3, …, n is the number of TDOA observation values. In summary, the coefficient matrix A = [A1 A2…A n ] T , and the free term I = [I1 I2…I n ] T .

[0058] Update the parameter approximation value (i.e., let ), and repeat the above iterative solving process until the parameter estimate tends to be stable, i.e., it satisfies:

[0059]

[0060] In the formula, ε is a very small positive real number artificially set, and it is recommended to be less than 0.1 mm.

[0061] Further, based on the above method, the embodiment of the application also provides an ultra-short baseline positioning system based on TDOA observation values and effective sound speed, comprising: an observation equation construction module, an observation equation linearization module and a least squares solving module, wherein,

[0062] The observation equation construction module is used to construct the mathematical relationship of the spatial geometric distance between the hydrophone and the sound source target according to the position vector of the hydrophone in the carrier coordinate system in the USBL system, and to establish an ultra-short baseline TDOA observation equation, wherein the unknown parameters of the ultra-short baseline TDOA observation equation include the effective sound speed parameter and the sound source position vector parameter;

[0063] The observation equation linearization module is used to linearize the ultra-short baseline TDOA observation equation by obtaining the effective sound speed approximation value and the sound source position vector approximation value, and bringing the effective sound speed approximation value and the sound source position vector approximation value into the ultra-short baseline TDOA observation equation;

[0064] The least squares solving module is used to iteratively solve the linearized ultra-short baseline TDOA observation equation by using the least squares method criterion, and to obtain the final effective sound speed and sound source target position vector according to the solving result.

[0065] Unless otherwise specifically stated, the relative steps, numerical expressions and numerical values of the components and steps set forth in these embodiments do not limit the scope of the application.

[0066] The various embodiments are described in the specification in a progressive manner, each embodiment focusing on different aspects of the other embodiments, and the same or similar parts between the embodiments can be mutually referred to. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method.

[0067] The units and method steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been described in the above description in general terms. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation does not exceed the scope of the present application.

[0068] Those skilled in the art can understand that all or part of the steps in the above method can be instructed by a program to complete the relevant hardware, and the program can be stored in a computer readable storage medium, such as a read-only memory, a magnetic disk or an optical disk, etc. Alternatively, all or part of the steps of the above embodiments can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiments can be implemented in the form of hardware or in the form of a software function module. The present application is not limited to any specific form of combination of hardware and software.

[0069] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present application, which are used to illustrate the technical solutions of the present application, and are not limiting. The protection scope of the present application is not limited thereto, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily think of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed by the present application, or make equivalent replacements to some of the technical features; and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An ultra-short baseline positioning method based on TDOA observations and effective sound velocity, characterized in that: Include: Based on the position vector of the hydrophone in the carrier coordinate system in the USBL system, the mathematical relationship of the spatial geometric distance between the hydrophone and the sound source target is established, and the ultra-short baseline TDOA observation equation is established. The unknown parameters of the ultra-short baseline TDOA observation equation include the effective sound velocity parameter and the sound source position vector parameter. The ultra-short baseline TDOA observation equation is expressed as: Δt ij is the TDOA observation value between ultra-short baseline hydrophone j and hydrophone i, P is the sound source position vector, c eff is the effective speed of sound, p i and p j are the known position vectors of hydrophone i and hydrophone j in the carrier coordinate system respectively; Obtain an effective sound velocity approximation and an approximate sound source position vector, and bring the effective sound velocity approximation and the sound source position vector approximation into the ultra-short baseline TDOA observation equation to linearize the ultra-short baseline TDOA observation equation; The linearized ultra-short baseline TDOA observation equation is iteratively solved using the least squares method, and the final effective sound velocity and sound source target position vector are obtained based on the solution.

2. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1, characterized in that: Construct the mathematical relationship between the spatial geometric distance between the hydrophone and the sound source target, including: The distance representing the propagation delay of the acoustic signal is expressed based on the time when the acoustic signal is transmitted, the time when the hydrophone receives the acoustic signal, and the effective speed of sound; The distance of the acoustic signal propagation delay is used and the mathematical relationship of the spatial geometric distance between the hydrophone and the sound source is established based on the position vectors of the hydrophone and the sound source in the carrier coordinate system.

3. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1 or 2, characterized in that: The mathematical relationship of spatial geometric distance is expressed as: ρ i =(p T p-2p T p i +p i T p i ) 1 / 2 , where ρ i is the distance of the acoustic signal propagation delay, and ρ i =c eff (t i -t0), c eff is the effective sound speed, t0 is the time when the sound signal is emitted, t i is the moment when hydrophone i receives the acoustic signal, p i and p are the position vectors of the hydrophone and the sound source in the carrier coordinate system, respectively.

4. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1, characterized in that: Establish the ultra-short baseline TDOA observation equation, including: Taking the effective sound velocity and the sound source position vector as unknown parameters, the ultra-short baseline TDOA observation equation is constructed based on the mathematical relationship of spatial geometric distance and the known position vector of the hydrophone in the carrier coordinate system.

5. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1, characterized in that: Get the approximate effective sound speed and the approximate sound source position vector, including: The average sound speed or specified sound speed is used as the effective sound speed approximation, and the sound source position vector approximation is determined based on the TDOA and propagation delay of the sound signal and the sound source direction and distance.

6. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1, characterized in that: The linearized ultra-short baseline TDOA observation equation is iteratively solved using the least squares criterion, including: The coefficient matrix and free terms of the least square error equation are expressed using the known position vector of the hydrophone in the carrier coordinate system and the unknown parameters; An observation equation iterative solution model is constructed based on the coefficient matrix, free terms and unknown parameters, so as to iteratively solve the model by updating the approximate values ​​of the unknown parameters until the unknown parameters reach a stable condition.

7. An ultra-short baseline positioning system based on TDOA observations and effective sound velocity, characterized in that: Contains: observation equation construction module, observation equation linearization module and least squares solution module, among which, The observation equation construction module is used to construct the mathematical relationship of the spatial geometric distance between the hydrophone and the sound source target based on the position vector of the hydrophone in the carrier coordinate system in the USBL system, and establish the ultra-short baseline TDOA observation equation. The unknown parameters of the ultra-short baseline TDOA observation equation include the effective sound velocity parameter and the sound source position vector parameter. The ultra-short baseline TDOA observation equation is expressed as: Δt ij is the TDOA observation value between ultra-short baseline hydrophone j and hydrophone i, P is the sound source position vector, c eff is the effective speed of sound, p i and p j are the known position vectors of hydrophone i and hydrophone j in the carrier coordinate system respectively; An observation equation linearization module is used to linearize the ultra-short baseline TDOA observation equation by obtaining an effective sound velocity approximation and an sound source position vector approximation and bringing the effective sound velocity approximation and the sound source position vector approximation into the ultra-short baseline TDOA observation equation; The least squares solution module is used to iteratively solve the linearized ultra-short baseline TDOA observation equation using the least squares criterion, and obtain the final effective sound speed and sound source target position vector based on the solution results.

8. An electronic device, characterized in that: include: at least one processor, and a memory coupled to the at least one processor; The memory stores a computer program, and the computer program can be executed by the at least one processor to implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 6 can be implemented.

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