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

Abstract

The invention relates to the technical field of ultra-short baseline positioning, in particular to an ultra-short baseline positioning method and system based on a TDOA observation value and an effective sound velocity, and the method comprises the steps: constructing a spatial geometric distance mathematical relationship between a hydrophone and a sound source target according to a position vector of the hydrophone in a USBL system in a carrier coordinate system, and building an ultra-short baseline TDOA observation equation; unknown parameters of the ultra-short baseline TDOA observation equation comprise an effective sound velocity parameter and a sound source position vector parameter; substituting the effective sound velocity approximate value and the sound source position vector approximate value into an ultra-short baseline TDOA observation equation to linearize the ultra-short baseline TDOA observation equation; and iteratively solving the linearized ultra-short baseline TDOA observation equation by using a least square method criterion, and obtaining a final effective sound velocity and a final sound source target position vector according to a solving result. The method can be suitable for a USBL system with TDOA as an original observation value, can avoid the influence of sound ray bending, is simple in calculation principle, and can be embedded into a novel USBL positioning system for use.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-short baseline positioning, and in particular to an ultra-short baseline positioning method and system based on TDOA observation values ​​and effective sound velocity. Background Art

[0002] Conventional ultra-short baseline positioning systems include two types of observations: the time difference of arrival (TDOA) of acoustic signals and the propagation delay. The time difference of arrival is used to determine the direction of the sound source, and the propagation delay is used to determine the distance of the sound source, and then the position of the sound source is determined by the direction and distance. Obviously, the traditional USBL positioning technology will be affected by the bending of the sound line, and the obtained sound source direction is actually the wave arrival direction of the sound wave arriving at the receiving array, rather than the true direction of the sound source. Moreover, an accurate effective sound speed is also required to accurately calculate the Euclidean distance from the sound source to the USBL array using the propagation delay of the acoustic signal. However, the effective sound speed cannot be accurately known. The existing method uses the average sound speed instead of the effective sound speed, which is not accurate; the existing method uses the sound line tracking correction to calculate the Euclidean distance, which requires the measurement of the sound speed profile of the working waters, which increases the workload in the field and reduces the working efficiency of the USBL system. Summary of the invention

[0003] To this end, the present invention provides an ultra-short baseline positioning method and system based on TDOA observation values ​​and effective sound velocity, which solves the problem that the positioning result is affected by sound line bending and unknown effective sound velocity in the existing ultra-short baseline positioning.

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

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

[0006] 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 an 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 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 results.

[0008] As the ultra-short baseline positioning method based on TDOA observation value and effective sound velocity of the present invention, further, a mathematical relationship of the spatial geometric distance between the hydrophone and the sound source target is constructed, including:

[0009] 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;

[0010] The distance of the acoustic signal propagation delay is used to establish a mathematical relationship of the spatial geometric distance between the hydrophone and the sound source based on the position vectors of the hydrophone and the sound source in the carrier coordinate system.

[0011] As the ultra-short baseline positioning method based on TDOA observation value and effective sound velocity of the present invention, further, 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 time 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.

[0012] As an ultra-short baseline positioning method based on TDOA observation values ​​and effective sound velocity of the present invention, further, an ultra-short baseline TDOA observation equation is established, including:

[0013] 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 using the known position vector of the hydrophone in the carrier coordinate system.

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

[0015] As the ultra-short baseline positioning method based on TDOA observation value and effective sound velocity of the present invention, further, obtaining the approximate value of the effective sound velocity and the approximate value of the sound source position vector includes:

[0016] 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 sound source distance.

[0017] As an ultra-short baseline positioning method based on TDOA observation values ​​and effective sound velocity of the present invention, further, the linearized ultra-short baseline TDOA observation equation is iteratively solved using the least squares criterion, including:

[0018] The coefficient matrix and free terms of the least square error equation are expressed by using the known position vector of the hydrophone in the carrier coordinate system and the unknown parameters;

[0019] 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.

[0020] On the other hand, the present invention also provides an ultra-short baseline positioning system based on TDOA observations and effective sound velocity, comprising: an observation equation construction module, an observation equation linearization module and a least squares solution module, wherein:

[0021] An observation equation construction module is used to construct a 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 an effective sound velocity parameter and a sound source position vector parameter;

[0022] 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 approximate sound source position vector, and bringing the effective sound velocity approximation and the sound source position vector approximation into the ultra-short baseline TDOA observation equation;

[0023] 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.

[0024] Beneficial effects of the present invention:

[0025] The present invention establishes an observation equation of TDOA observation value by using effective sound speed, and takes the effective sound speed and sound source position parameters as unknown parameters, and then adopts a nonlinear least square method to synchronously solve the effective sound speed and sound source position parameters. The present invention can be applicable to a USBL system using TDOA as an original observation value, does not require propagation delay, does not require measurement of sound speed profile, and does not require provision of effective sound speed information. Only by using no less than 4 TDOA observation values, underwater target positioning and effective sound speed calculation can be completed, and the influence of sound line bending can be avoided. The calculation principle is simple, and the present invention can be embedded in a new USBL positioning system for use, and is helpful to improve the design of the USBL system. The present invention has good application prospects in the field of ultra-short baseline positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the ultra-short baseline positioning process based on TDOA observation value and effective sound velocity in the embodiment;

[0027] Figure 2 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 solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and technical solutions.

[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 propagation paths of the acoustic signal from the sound source to each hydrophone are theoretically very close, that is, the propagation paths are similar. When the propagation paths of the acoustic signal are the same, the effective sound speed corresponding to each sound line is also the same. Figure 1 As shown, an ultra-short baseline positioning method based on TDOA observation value and effective sound velocity is provided, including:

[0030] S101. Construct a 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 an ultra-short baseline TDOA observation equation, wherein the unknown parameters of the ultra-short baseline TDOA observation equation include an effective sound velocity parameter and a sound source position vector parameter.

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

[0032] 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;

[0033] The distance of the acoustic signal propagation delay is used to establish a mathematical relationship of the spatial geometric distance between the hydrophone and the sound source based on the position vectors of the hydrophone and the sound source in the carrier coordinate system.

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

[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 propagation delay of the acoustic signal, 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 propagation time of the intrinsic sound line), t0 is the time when the sound signal is emitted, and t i is the moment when hydrophone i receives the acoustic signal.

[0037] Taking the effective sound speed 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. Among them, 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 = [xyz] T is the sound source position vector; p j =[x j y j z j ] T and p i =[x i y i z i ] T is the known hydrophone position vector.

[0040] S102, obtaining an effective sound velocity approximation and an approximate sound source position vector approximation, and bringing the effective sound velocity approximation and the approximate sound source position vector approximation into an 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 used as an 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 through the sound source direction and the sound source distance.

[0042] The specified sound speed value may be set to about 1500 m / s, which may be adjusted according to the actual scenario. The approximate value of the sound source position vector may be calculated using an existing conventional method.

[0043] S103, using the least squares criterion to iteratively solve the linearized ultra-short baseline TDOA observation equation, and obtaining the final effective sound speed and sound source target position vector based on the solution result.

[0044] Specifically, the linearized ultra-short baseline TDOA observation equation is iteratively solved using the least squares criterion, which may include:

[0045] The coefficient matrix and free terms of the least square error equation are expressed by using the known position vector of the hydrophone in the carrier coordinate system and the unknown parameters;

[0046] 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.

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

[0048] The sound source position and effective sound velocity are taken as unknown parameters, and the approximate values ​​of the parameters are substituted into the linearized observation equation:

[0049]

[0050] In the formula, p and c eff All are approximate values.

[0051] According to the least squares principle, the optimal estimate of the unknown parameters is calculated as follows:

[0052]

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

[0054]

[0055] The expressions for the elements in the free term l are as follows:

[0056]

[0057] Where k = 1, 2, 3, ..., n is the number of TDOA observations. In summary, the coefficient matrix A = [A1 A2 ... A n ] T , free term l=[l1 l2…l n ] T .

[0058] Update the approximate value of the parameter (i.e. ), and repeat the above iterative solution process until the parameter estimation tends to be stable, that is, it satisfies:

[0059]

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

[0061] Furthermore, based on the above method, an embodiment of the present invention also provides an ultra-short baseline positioning system based on TDOA observations and effective sound velocity, comprising: an observation equation construction module, an observation equation linearization module and a least squares solution module, wherein:

[0062] An observation equation construction module is used to construct a 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 an effective sound velocity parameter and a sound source position vector parameter;

[0063] 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 approximate sound source position vector, and bringing the effective sound velocity approximation and the sound source position vector approximation into the ultra-short baseline TDOA observation equation;

[0064] 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.

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

[0066] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0067] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation is not considered to be beyond the scope of the present invention.

[0068] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk or an optical disk. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of software function modules. The present invention 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 only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall 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: According to the position vector of the hydrophone in the carrier coordinate system of the USBL system, a mathematical relationship of the spatial geometric distance between the hydrophone and the sound source target is constructed, and an ultra-short baseline TDOA observation equation is established, wherein the unknown parameters of the ultra-short baseline TDOA observation equation include an effective sound velocity parameter and a sound source position vector parameter; 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 an 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 results.

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 of 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 to establish a mathematical relationship of the spatial geometric distance between the hydrophone and the sound source 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: 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 time 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 using 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 or 4, characterized in that: The ultra-short baseline TDOA observation equation is expressed as: Δt ij is the TDOA observation value between the ultra-short baseline hydrophone j and the 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.

6. The ultra-short baseline positioning method based on TDOA observations and effective sound velocity according to claim 1, characterized in that: Get the approximate value of the effective sound speed and the approximate value of the 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 sound source distance.

7. 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 by 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.

8. 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, An observation equation construction module is used to construct a mathematical relationship of spatial geometric distance between a hydrophone and a 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 an effective sound velocity parameter and a sound source position vector parameter; 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 approximate sound source position vector, 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.

9. 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 7.

10. 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 7 can be implemented.

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