System for improving positioning precision under complex underwater acoustic channel and optimization method

Abstract

The invention provides a system for improving positioning precision under a complex underwater acoustic channel and an optimization method, and relates to the field of underwater positioning. The system for improving the positioning precision under the complex underwater acoustic channel comprises a time delay estimation module, a sound velocity profile data module, a sound ray correction module, a slope distance value precision module and a precision improvement module, and the time delay estimation module is mainly used for obtaining more accurate time delay data; the sound velocity profile data module is mainly used for acquiring sound velocity profile data of a positioning area. According to the method, a real sound ray path is estimated by using a sound ray correction method, measurement errors of bubbles in water, sound velocity change and position and propagation time are considered, the positioning precision is further improved, and the comprehensive optimization method enables the system to accurately reflect the real position of a target in a complex underwater environment, so that the positioning accuracy is improved. The overall performance of underwater target positioning is remarkably improved, and the actual requirement of high-precision positioning is met.

Description

Technical Field

[0001] The present invention relates to the field of underwater positioning, and in particular to a system and an optimization method for improving positioning accuracy in a complex underwater acoustic channel. Background Art

[0002] The application of underwater acoustic positioning systems in marine engineering undoubtedly plays a vital role, and its importance is self-evident. In the vast field of marine oil and gas extraction, underwater acoustic positioning technology is like a precise ocean guide, which can not only help engineers accurately lock the wellhead location, but also effectively track the dynamic trajectory of ships and equipment, ensuring the precise layout of submarine pipelines and various facilities. The application of this technology has greatly improved the efficiency and safety of oil and gas extraction.

[0003] Similarly, under the mysterious veil of seabed mineral resources that has not been fully revealed, underwater acoustic positioning has become an indispensable exploration tool. It helps scientists go deep into the seabed and accurately locate mineral resources, providing strong technical support for navigation, mineral resource investigation and evaluation. In addition, this technology is also widely used in environmental monitoring and ecological assessment, contributing wisdom and strength to the protection of the marine ecological environment.

[0004] In the grand project of cross-sea channel construction, the hydroacoustic positioning system is also indispensable, especially in the complex and delicate construction process of immersed tube tunnels. Hydroacoustic positioning technology, with its unique advantages, ensures the precise sinking and docking of pipe sections underwater. This link requires extremely high positioning accuracy, and any slight deviation may lead to immeasurable consequences.

[0005] However, it is worth noting that improving positioning accuracy in a complex and ever-changing underwater acoustic channel environment is not an easy task. The particularities of the marine environment, such as changes in currents, temperature, and salinity, all significantly affect the propagation of underwater acoustic signals. These factors intertwine to form a challenging underwater acoustic channel environment, making the transmission of positioning signals complex and difficult. Therefore, how to improve the accuracy of underwater acoustic positioning systems in such an environment has become a technical challenge that needs to be urgently addressed in the field of marine engineering.

[0006] After searching, the Chinese patent with publication number CN201910103931.7 discloses a multi-target underwater acoustic positioning delay estimation algorithm, which adopts broadband delay estimation technology to improve the accuracy of delay estimation; the Chinese patent with publication number CN202410822931.3 discloses a high-precision underwater acoustic positioning method and system, which is used to solve the problem of inaccurate underwater acoustic positioning. The above patents do not consider the multipath effect, channel attenuation, low positioning accuracy and other problems caused by the complex underwater acoustic channel environment. Therefore, based on the complex underwater acoustic channel environment, the present invention proposes a system and optimization method to improve positioning accuracy, which can achieve high-precision positioning of underwater targets within a larger coverage range.

[0007] Therefore, those skilled in the art provide a system and an optimization method for improving positioning accuracy in complex underwater acoustic channels to solve the problems raised in the above background technology. Summary of the Invention

[0008] (1) Technical problems solved

[0009] In response to the shortcomings of the existing technology, the present invention provides a system and optimization method for improving positioning accuracy in complex underwater acoustic channels, which solves the problems of multipath effect, channel attenuation, low positioning accuracy, etc. caused by complex underwater acoustic channel environments.

[0010] (2) Technical solution

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0012] A system for improving positioning accuracy in complex underwater acoustic channels includes a time delay estimation module, a sound velocity profile data module, a sound ray correction module, a slant range value precision module, and an accuracy improvement module. The time delay estimation module is mainly used to obtain more accurate time delay data.

[0013] The sound velocity profile data module is mainly used to obtain the sound velocity profile data of the positioning area;

[0014] The sound ray correction module is mainly used to establish a sound ray correction model and estimate the real sound ray path in a complex underwater acoustic channel;

[0015] The slope distance value precision module is mainly used to calculate a more accurate slope distance value;

[0016] The precision improvement module is mainly used to improve the positioning accuracy of underwater targets by using an estimation method.

[0017] Through the above technical solution, the system and optimization method for improving positioning accuracy in complex underwater acoustic channels use the sound line correction method to estimate the true sound line path, taking into account bubbles in the water, changes in sound speed, and measurement errors of position and propagation time, further improving positioning accuracy. This comprehensive optimization method enables the system to accurately reflect the true position of the target in complex underwater environments, significantly improving the overall performance of underwater target positioning and meeting the actual needs of high-precision positioning.

[0018] Furthermore, the delay estimation module uses the generalized cross-correlation method to perform matched filtering on the signal received by the beacon, which can obtain a cross-correlation function with a steeper extreme value in a complex underwater acoustic channel, obtain more accurate delay data, and improve positioning accuracy;

[0019] Through the above technical solution, the specific principle is: first, the two received signals x1 and x2 are pre-filtered, and then the cross-correlation function of the two pre-processed output signals y1 and y2 is calculated, which is called the GCC function. Finally, the peak value of the GCC function is detected, and the corresponding time value is the delay estimate value D.

[0020] Furthermore, the sound velocity profile data module needs to first obtain the sound velocity profile data of the positioning area to improve the accuracy of the sound line correction. The measurement methods include but are not limited to direct measurement method, indirect measurement method, etc.

[0021] Through the above technical solution, the specific principles are as follows:

[0022] Direct measurement method: Using instruments such as a sound velocity profiler to directly measure the sound velocity in seawater. This method usually requires measuring the propagation time of the sound signal multiple times within a set distance to calculate the sound velocity. At the same time, it is also necessary to obtain water depth and temperature information through pressure sensors, temperature meters and other equipment;

[0023] Indirect measurement method: Use CTD (Conductivity, Temperature, Depth) elements to measure the temperature, salinity, and static pressure (depth) of seawater, and then calculate the sound speed in seawater based on the sound speed empirical model formula

[0024] Furthermore, the sound ray correction module includes but is not limited to an improved constant gradient sound ray tracking method, an equivalent sound velocity profile method, etc., which can estimate the true sound ray path in a complex underwater acoustic channel, making the propagation path more accurate and improving positioning accuracy;

[0025] Through the above technical solution, the specific principles are as follows:

[0026] Improved constant gradient ray tracing algorithm: According to the propagation law of sound velocity, C and θ are used to represent the speed and direction of the sound wave at a vertical depth of z, respectively. The change gradient of the sound velocity in the i-th layer is gi The calculation formula can be expressed as:

[0027]

[0028] The propagation direction and speed of the sound wave satisfy the Snell law. Under the condition of constant gradient change of the sound speed, the actual propagation trajectory of the beam in the i-th layer is a continuous one corresponding to a certain curvature radius R. i The arc segment, R i =|1 / pg i |, p is the Snell constant.

[0029] The sound velocity function of the ray tracing algorithm adopts the harmonic average sound velocity. Assume that the sound velocity in the i-th layer has a constant gradient g i Changes, within its layer (z∈[z i , z i+1 ]) of the speed of sound function C i (z) is expressed as:

[0030] C i (z) = C i +g i (zz i )#(2)

[0031] According to Mayer's view, the propagation time of the sound velocity in the i-th layer in the unimproved conventional gradient ray tracing algorithm is:

[0032]

[0033] In the improved conventional gradient ray tracking algorithm, the time required for the sound wave to pass through the arc element ds is dt = ds / C, so the sound wave from s i Depth point propagation to s i+1 Time required for depth point t i+1 It can be expressed as:

[0034]

[0035] like Figure 1 As shown in Figure 4, the relationship between the vertical element dz and ds of the sound line is ds = dz / cosθ, where θ is the grazing angle of the beam at the arc element ds. Substituting this into formula (4) yields:

[0036]

[0037] Since the speed of sound is constant with a speed gradient g i Propagation, according to formula (1), formula (5) can be written as:

[0038]

[0039] Based on Snel's theorem, formula (6) can be transformed into:

[0040]

[0041] Assume that the time it takes for the beam to travel through the entire water column is T′ V , then:

[0042]

[0043] The distance the sound line travels (S-S0) and the time T' it takes to travel the entire water column arc are used to calculate the distance the sound line travels (S-S0) and the time it takes to travel the entire water column arc V , the average sound speed C′ in the entire water column arc path can be obtained H :

[0044]

[0045] When the sound ray passes through the i-th layer and enters the i+1-th layer, the vertical displacement Δz of the i-th layer sound ray i , Δx i and t i for:

[0046]

[0047] In layered sound ray tracking, in addition to the calculation of the entire layer, the calculation of the remaining layers needs to be determined based on the remaining propagation time: when the sound ray propagates in the i-th layer, whether the sound ray ends at point r in the layer, then the remaining time t all Represents the total propagation time.

[0048] According to the above analysis method, the corresponding vertical displacement Δz can be obtained r , horizontal displacement Δx r and propagation time t r for:

[0049]

[0050] After completing the calculation of the horizontal and vertical displacements of the entire layer and the remaining layers, if the entire water column is divided into N layers, the total horizontal distance x and vertical distance z of the sound line are equal to N-1 layers Δx i and Δz i The superposition and the last layer of Δx r and Δz r ,Right now

[0051]

[0052] Effective sound velocity profile method: The equivalent sound velocity profile method mainly uses the principle of area difference, such as Figure 2As shown in the figure, the curve starting from C0 is the actual sound velocity profile, and C0-CB is the constant gradient sound velocity profile. The area difference between the actual sound velocity profile and the constant gradient sound velocity profile is equal to 0, so C0-CB can be used to replace the actual sound velocity profile. In the equivalent sound velocity profile method, the most important thing is to calculate the equivalent gradient g e Assuming that the area difference between the zero sound velocity profile and the actual sound velocity profile is S, the equivalent gradient ge is calculated as follows:

[0053]

[0054] The calculation formula of the time t of the entire layer is as follows:

[0055]

[0056] Furthermore, the slant distance value precision module combines the real sound line path and time delay data after sound line correction to calculate the real slant distance value, thereby improving positioning accuracy. Underwater target positioning methods include but are not limited to spherical intersection positioning method and hyperbolic intersection positioning method. After obtaining the slant distance value between the positioning beacon and the positioning node, the coordinates of the positioning beacon to be measured can be obtained using the underwater target positioning method.

[0057] Through the above technical solution, the specific principles are as follows:

[0058] Given the time delay data, the horizontal and vertical distances of the sound line propagation can be obtained according to equations (10), (11), and (12). Using the Pythagorean theorem, the slant distance value can be calculated:

[0059]

[0060] Least square method + Newton iteration method: Set the source position obtained by the least square method as the initial value (x (k) ,y (k) , z (k) ), substitute the relationship of Newton iteration method, and solve the position after iteration as (x (k+1) ,y (k+1) , z (k+1) );

[0061] (x (k) ,y (k) , z (k) ) and (x (k+1) ,y (k+1) , z (k+1) ) into the redundant function expression:

[0062] Using the optimization method: ε=min(ε0,ε i ), ε0 is a value given according to the ranging accuracy requirement;

[0063] Calculate Δ k+1 =max(|x (k+1) -x (k) |,|y (k+1) -y (k) |,|z (k+1) -z (k) |);

[0064] Determine whether the condition Δ is met k+1 <Δ (Δ is the given accuracy requirement) and f i (x, y, z)<ε, if it is satisfied, the iteration process ends and the output is (x (k+1) ,y (k+1) , z (k+1) ), if it is not satisfied, the solution value is used as the initial value and the Newton iteration steps are continued until the condition is satisfied;

[0065] Spherical intersection positioning method: The positioning target and array elements satisfy the following equations:

[0066]

[0067] Subtract the 2nd to 4th equations from the 1st equation in the system and write them in matrix form:

[0068]

[0069] X=[xyz] T #(4)

[0070] Where, As long as the inverse matrix of A exists, the unique solution of the equation can be found:

[0071] X=A -1 B#(5)

[0072] The position vector X of the positioning target can be calculated.

[0073] Furthermore, the improved constant gradient ray tracking method needs to first obtain data on the sound ray incident angle. Methods for calculating the sound ray incident angle include but are not limited to Newton's method, chord intercept method, and P-order secant method.

[0074] Furthermore, S1. Using the generalized cross-correlation method to perform matched filtering on the signal received by the beacon can effectively suppress noise interference, improve the accuracy and robustness of delay estimation, and obtain more accurate delay data;

[0075] S2. Acquire the sound velocity profile data of the positioning area;

[0076] S3. Use the sound ray correction method to establish a sound ray correction model to estimate the true sound ray path in complex underwater acoustic channels, achieving high-precision measurement of target distances in complex environments;

[0077] S4. Combine the corrected true sound path and delay data to calculate a more accurate slant range value.

[0078] S5. Consider the impact of water bubble and sound speed measurement errors, position measurement errors, and propagation time measurement errors on positioning accuracy. Based on the obtained slant range value, use the estimation method to reduce the measurement error and accelerate the rapid convergence of the nonlinear equation, thereby improving the solution accuracy and efficiency.

[0079] (3) Beneficial effects

[0080] The present invention provides a system and optimization method for improving positioning accuracy in complex underwater acoustic channels. It has the following beneficial effects:

[0081] 1. The present invention provides a system and an optimization method for improving positioning accuracy in complex underwater acoustic channels. The system and the optimization method for improving positioning accuracy significantly improve the accuracy of time delay estimation through the generalized cross-correlation method. By optimizing each step of the positioning method, the interference caused by the complex underwater acoustic channel is reduced, and noise interference can be effectively suppressed. High-precision positioning of the target distance in a complex environment can be achieved, so that in a complex underwater acoustic channel environment, the interference caused by multipath effects and channel attenuation can be effectively suppressed, thereby ensuring that the system can still achieve high-precision target distance measurement in a noisy environment, thereby improving the reliability and accuracy of underwater positioning.

[0082] 2. The present invention provides a system and an optimization method for improving positioning accuracy in complex underwater acoustic channels. The system and the optimization method for improving positioning accuracy in complex underwater acoustic channels use the sound line correction method to estimate the true sound line path, taking into account bubbles in the water, changes in sound speed, and measurement errors of position and propagation time, thereby further improving positioning accuracy. This comprehensive optimization method enables the system to accurately reflect the true position of the target in a complex underwater environment, significantly improving the overall performance of underwater target positioning and meeting the actual needs of high-precision positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 Schematic diagram of the improved constant gradient ray tracking algorithm of the present invention;

[0084] Figure 2 Schematic diagram of the equivalent sound velocity profile method of the present invention;

[0085] Figure 3 is a flow chart of the generalized cross-correlation method of the present invention;

[0086] Figure 4is a flow chart of the present invention;

[0087] Figure 5 This is a comparison chart of the positioning results after sound ray correction and without sound ray correction in the present invention. DETAILED DESCRIPTION

[0088] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0089] Example:

[0090] like Figure 1-5 As shown, the present invention provides a system and optimization method for improving positioning accuracy in complex underwater acoustic channels. The system includes a time delay estimation module, a sound velocity profile data module, a sound ray correction module, a slant range value precision module and an accuracy improvement module. The time delay estimation module is mainly used to obtain more accurate time delay data;

[0091] The sound velocity profile data module is mainly used to obtain the sound velocity profile data of the positioning area;

[0092] The sound ray correction module is mainly used to establish a sound ray correction model and estimate the real sound ray path in a complex underwater acoustic channel;

[0093] The slope distance value precision module is mainly used to calculate a more accurate slope distance value;

[0094] The precision improvement module is mainly used to improve the positioning accuracy of underwater targets by using an estimation method;

[0095] High-precision positioning of underwater targets can be achieved within a large coverage area. The implementation steps of this optimization method are as follows:

[0096] 1) To obtain a cross-correlation function with steeper extreme values ​​in complex underwater acoustic channels, the generalized cross-correlation method is used to perform matched filtering on the signal received by the beacon to obtain high-precision time delay data. The specific principle is as follows:

[0097] First, pre-filter the two received signals x1 and x2, then calculate the cross-correlation function of the two pre-processed output signals y1 and y2, which is called the GCC function. Finally, perform peak detection on the GCC function, and the corresponding time value is the delay estimation value D. The specific flow chart is as follows Figure 2 shown.

[0098] 2) Obtain sound velocity profile data of the positioning area. Measurement methods include but are not limited to direct measurement and indirect measurement. The specific principles are as follows:

[0099] Direct measurement method:

[0100] Directly measuring the speed of sound in seawater using instruments such as sound velocity profilers. This method typically requires measuring the propagation time of the sound signal multiple times over a predetermined distance to calculate the speed of sound. Furthermore, water depth and temperature information is acquired through pressure sensors and temperature meters.

[0101] Indirect measurement method:

[0102] The temperature, salinity, and static pressure (depth) of seawater are measured using a CTD (Conductivity, Temperature, Depth) element, and the speed of sound in seawater is calculated based on the empirical sound speed model formula.

[0103] 3) Using the sound ray correction method, establish a sound ray correction model and estimate the true sound ray path in the complex underwater acoustic channel. The sound ray correction method includes but is not limited to the improved constant gradient sound ray tracking method and the equivalent sound velocity profile method. The specific principle is as follows:

[0104] Improved constant gradient ray tracing algorithm:

[0105] According to the sound velocity profile data, an improved constant gradient sound ray tracking method is used to perform sound ray correction and estimate the sound ray path in a complex underwater acoustic channel. The specific steps of the method are as follows.

[0106] First, find the vertical displacement Δz of the sound ray in layer i when it passes through layer i and enters layer i+1. i , Δx i and t i for:

[0107]

[0108] Then, in layered sound ray tracking, in addition to the calculation of the entire layer, the calculation of the remaining layers needs to be determined based on the remaining propagation time: when the sound ray propagates in the i-th layer, whether the sound ray ends at point r in the layer, then the remaining time t all Represents the total propagation time.

[0109] According to the above analysis method, the corresponding vertical displacement Δz can be obtained r , horizontal displacement Δx r and propagation time t r for:

[0110]

[0111] Finally, after completing the calculation of the horizontal and vertical displacements of the entire layer and the remaining layers, if the entire water column is divided into N layers, the total horizontal distance x and vertical distance z of the sound line are equal to N-1 layers Δx i and Δz i The superposition and the last layer of Δx r and Δz r ,Right now

[0112]

[0113] Equivalent sound velocity profile method:

[0114] The equivalent sound velocity profile method mainly uses the principle of area difference, such as Figure 2 As shown in the figure, the curve starting from C0 is the actual sound velocity profile, and C0-CB is the constant gradient sound velocity profile. The area difference between the actual sound velocity profile and the constant gradient sound velocity profile is equal to 0, so C0-CB can be used to replace the actual sound velocity profile. In the equivalent sound velocity profile method, the most important thing is to calculate the equivalent gradient g e Assuming that the area difference between the zero sound velocity profile and the actual sound velocity profile is S, the equivalent gradient ge is calculated as follows:

[0115]

[0116] The calculation formula of the time t of the entire layer is as follows:

[0117]

[0118] 4) Combining the corrected true sound path and delay data, the true slant range value is calculated to improve positioning accuracy. The specific principles are as follows:

[0119] Given the time delay data, the horizontal and vertical distances of the sound line propagation can be obtained according to equations (10), (11), and (12). Using the Pythagorean theorem, the slant distance value can be calculated:

[0120]

[0121] 5) Consider the impact of bubbles in water, sound speed measurement error, position measurement error and propagation time measurement error on positioning accuracy, and improve the positioning accuracy of the target;

[0122] 6) Based on the obtained slant distance value d, use the estimation method to improve the positioning accuracy of the underwater target. The underwater target positioning method includes but is not limited to the least squares method + Newton iteration method, spherical intersection positioning method, etc. The specific principle is:

[0123] Least squares method + Newton iteration method:

[0124] The source position obtained by the least squares method is set as the initial value (x (k) ,y (k) , z (k) ), substitute the relationship of Newton iteration method, and solve the position after iteration as (x (k+1) ,y (k+1) , z (k+1) );

[0125] (x (k) ,y (k) , z (k) ) and (x (k+1) ,y (k+1) , z (k+1) ) into the redundant function expression: Using the optimization method: ε=min(ε0,ε i ), ε0 is a value given according to the ranging accuracy requirement;

[0126] Calculate Δ k+1 =max(|x (k+1) -x (k) |,|y (k+1) -y (k) |,|z (k+1) -z (k) |);

[0127] Determine whether the condition Δ is met k+1 <Δ (Δ is the given accuracy requirement) and f i (x, y, z)<ε, if it is satisfied, the iteration process ends and the output is (x (k+1) ,y (k+1) , z (k+1) ), if it is not satisfied, the solved value is used as the initial value and the Newton iteration steps are continued until the condition is met.

[0128] Spherical intersection positioning method:

[0129] The positioning target and array elements satisfy the following equations:

[0130]

[0131] Subtract the 2nd to 4th equations from the 1st equation in the system and write them in matrix form:

[0132]

[0133] X=[xyz] T #(10)

[0134] Where, As long as the inverse matrix of A exists, the unique solution of the equation can be found:

[0135] X=A -1 B#(11)

[0136] The position vector X of the positioning target can be calculated.

[0137] Positioning results such as Figure 5 As shown in the figure, when positioning is performed without sound ray correction, it can be found that the error of the horizontal coordinate is 4.44m and the error of the vertical coordinate is 2.08m; after adopting the improved sound ray correction method, the error of the horizontal coordinate is 0.008m and the error of the vertical coordinate is 0.69m. Based on this result, it can be found that the method of the present invention significantly improves the positioning accuracy of underwater targets.

[0138] Table 1 Positioning results

[0139]

[0140] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A system for improving positioning accuracy in complex underwater acoustic channels, comprising a time delay estimation module, a sound velocity profile data module, a sound ray correction module, a slant range value precision module, and an accuracy improvement module, characterized by: The delay estimation module is mainly used to obtain more accurate delay data; The sound velocity profile data module is mainly used to obtain the sound velocity profile data of the positioning area; The sound ray correction module is mainly used to establish a sound ray correction model and estimate the real sound ray path in a complex underwater acoustic channel; The slope distance value precision module is mainly used to calculate a more accurate slope distance value; The precision improvement module is mainly used to improve the positioning accuracy of underwater targets by using an estimation method.

2. The system for improving positioning accuracy in complex underwater acoustic channels according to claim 1, characterized in that: The time delay estimation module uses the generalized cross-correlation method to perform matched filtering on the signal received by the beacon, which can obtain a cross-correlation function with a steeper extreme value in a complex underwater acoustic channel, obtain more accurate time delay data, and improve positioning accuracy.

3. The system for improving positioning accuracy in complex underwater acoustic channels according to claim 1, characterized in that: The sound velocity profile data module needs to first obtain the sound velocity profile data of the positioning area to improve the accuracy of sound line correction. The measurement methods include but are not limited to direct measurement method, indirect measurement method, etc.

4. The system for improving positioning accuracy in complex underwater acoustic channels according to claim 1, characterized in that: The sound ray correction module includes but is not limited to an improved constant gradient sound ray tracking method, an equivalent sound velocity profile method, etc., which can estimate the real sound ray path in a complex underwater acoustic channel, making the propagation path more accurate and improving positioning accuracy.

5. The system for improving positioning accuracy in complex underwater acoustic channels according to claim 1, characterized in that: The slant distance value precision module combines the real sound line path and time delay data after sound line correction to calculate the real slant distance value, thereby improving positioning accuracy. The underwater target positioning method includes but is not limited to the spherical intersection positioning method and the hyperbolic intersection positioning method. After obtaining the slant distance value between the positioning beacon and the positioning node, the coordinates of the positioning beacon to be measured can be obtained using the underwater target positioning method.

6. The system for improving positioning accuracy in complex underwater acoustic channels according to claim 4, characterized in that: The improved constant gradient ray tracking method needs to first obtain data on the sound ray incident angle. Methods for calculating the sound ray incident angle include but are not limited to Newton's method, chord intercept method, and P-order secant method.

7. A system for improving positioning accuracy in complex underwater acoustic channels according to any one of claims 1 to 7, characterized in that: The optimization method is as follows: S1. Using the generalized cross-correlation method, matched filtering is performed on the beacon signal. This effectively suppresses noise interference, improves the accuracy and robustness of delay estimation, and obtains more accurate delay data. S2. Acquire the sound velocity profile data of the positioning area; S3. Use the sound ray correction method to establish a sound ray correction model to estimate the true sound ray path in complex underwater acoustic channels, achieving high-precision measurement of target distances in complex environments; S4. Combine the corrected true sound path and delay data to calculate a more accurate slant range value. S5. Consider the impact of water bubble and sound speed measurement errors, position measurement errors, and propagation time measurement errors on positioning accuracy. Based on the obtained slant range value, use the estimation method to reduce the measurement error and accelerate the rapid convergence of the nonlinear equation, thereby improving the solution accuracy and efficiency.

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