A multi-beam depth sounding non-concentric array homing method and system

Abstract

The invention relates to the underwater measurement technology field of a multi-beam bathymetric system, and discloses a multi-beam bathymetric non-concentric array homing method and system, the method comprising: for a determined initial value of water depth, based on changing the projection angle of the transmitting cone and the projection angle of the receiving cone, the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath where a certain water depth value is located underwater, and a minimum constraint problem is constructed; the optimal solution of the minimum constraint problem is solved to obtain the intersection position of the transmitting surface and the receiving surface on the isobath where the initial value of the water depth is located, and the two-way propagation time of the acoustic signal is calculated; the water depth value is iteratively corrected, and the initial value of the projection angle of the transmitting cone and the initial value of the projection angle of the receiving cone are updated using the optimal solution, until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold. The method is based on a propagation surface model, and while achieving high-precision bathymetry, the calculation efficiency of the multi-beam detection system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of underwater measurement of ocean acoustic seabed topography detection and multi-beam bathymetry systems, and in particular to a multi-beam bathymetry non-concentric array homing method and system. Background Art

[0002] The multi-beam bathymetry system is one of the basic equipment for ocean terrain detection, and homing calculation is an important part of the multi-beam bathymetry system. The multi-beam bathymetry system transmits sonar signals to the seabed through the sonar transmitting array. After backscattering by the seabed sediment, the echo signal is received by the sonar receiving array. Through signal processing algorithms such as wave arrival time estimation, the receiving beam angle and the propagation time of the sound signal from transmission to reception, referred to as the two-way propagation time of the sound signal, are calculated. Combining the transmitting beam angle, receiving beam angle, two-way propagation time of the sound signal, sound speed profile, hull position and attitude information, etc., the seabed beam footprint, that is, the location of the sounding point, is obtained through homing calculation. The multi-beam bathymetry system obtains the topographic information of the seabed through multiple measurements. The existing homing calculation methods are divided into two categories: concentric array algorithms and non-concentric array algorithms.

[0003] The concentric array algorithm of the homing calculation method assumes that the center of the transmitting array and the center of the receiving array are located at the same position, the transmitting surface of the acoustic signal is a cone with the center of the transmitting array as the vertex, and the receiving surface of the acoustic signal is a cone with the center of the receiving array as the vertex. Based on the common vertex assumption, the intersection of the two common vertex cones is solved to obtain the synthetic beam vector, and then the location of the sounding point is obtained by tracking the sound velocity profile sound line. This method has a simple model and a small amount of calculation, but there is a systematic error caused by the concentric array assumption.

[0004] The non-concentric array algorithm corrects this error and establishes a propagation surface model. The emission surface of the acoustic signal is still a conical surface, but affected by the change in the speed of sound in the seawater, the propagation surface becomes an emission surface. Similarly, the receiving surface can be obtained. The intersection of the emission surface and the receiving surface at the same water depth is calculated by fitting the intersection of the sound lines in different directions at the same water depth, and the intersection of the emission and receiving surfaces at the water depth and the corresponding two-way propagation time of the acoustic signal are interpolated. By calculating the intersection points and the two-way propagation time of the acoustic signal at different water depths, the position of the sounding point is interpolated according to the actual two-way propagation time of the acoustic signal. This method has a more accurate model, but there are problems such as complex model and large calculation, and there is an interpolation error. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and proposes a multi-beam sounding non-concentric array homing method. The present invention also discloses a multi-beam sounding non-concentric array homing system. The method is based on a propagation surface model and can achieve high-precision sounding while improving the computational efficiency of the multi-beam detection system.

[0006] In one aspect, the present invention provides a multi-beam depth sounding non-concentric array homing method, comprising:

[0007] Step 1: Determine the initial value of water depth, the initial value of the projection angle of the transmitting cone, the initial value of the projection angle of the receiving cone, the actual two-way propagation time of the acoustic signal, and the threshold value of the set propagation time error;

[0008] Step 2: For the initial value of water depth, by changing the projection angle of the transmitting cone and the projection angle of the receiving cone, the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath at a certain water depth value underwater, and the minimum constraint problem is constructed;

[0009] Step 3: Using the initial values ​​of the projection angle of the transmitting cone and the initial values ​​of the projection angle of the receiving cone, the optimal solution of the projection angle of the transmitting cone and the projection angle of the receiving cone in the constructed minimum constraint problem is solved to obtain the intersection position of the transmitting surface and the receiving surface at the isobath where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal;

[0010] Step 4: Iteratively correct the water depth value, use the corrected water depth value to update the initial water depth value, and use the optimal solution of the transmitting cone projection angle and the optimal solution of the receiving cone projection angle to update the initial value of the transmitting cone projection angle and the initial value of the receiving cone projection angle, until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold.

[0011] In an improved multi-beam bathymetric non-concentric array homing method, the initial water depth z0 is determined by:

[0012] according to The initial value of water depth z0 is obtained by ray tracing, so that it satisfies the following formula:

[0013]

[0014] Where tt is the actual two-way propagation time of the acoustic signal, θ c is the composite beam vector V c The grazing angle corresponding to the starting point of the sound line, θ c =arccos(V c ·Z1), Z1=[0 0 -1] Τ for z Negative axis direction, c tr is the initial launch water depth z tr The speed of sound at the depth z, c(z) is the speed of sound at the depth z, V c =[x c y c z c ] Τ , which is obtained by using the transmitting beam angle, receiving beam angle and the three-dimensional attitude angle of the hull.

[0015] In an improved multi-beam bathymetric non-concentric array homing method, the initial values ​​of the transmitting cone projection angle α0 and the receiving cone projection angle β0 are determined by the following formulas:

[0016]

[0017] Among them, [x c1 y c1 z c1 ] Τ =Γ1 Τ ·V c is the composite beam vector V c The vector without the ship attitude correction at the time of launch, [x c2 y c2 z c2 ] Τ =Γ2 Τ ·V c is the composite beam vector V c The vector that has not been corrected by the ship's attitude at the time of reception, Γ1 is the ship's attitude rotation matrix at the time of transmission, and Γ2 is the ship's attitude rotation matrix at the time of reception.

[0018] In an improved multi-beam depth sounding non-concentric array homing method, step 2 includes: based on the starting point of the transmitted sound line being located at the center of the transmitting array A (x tr ,y tr ,z tr ), calculate the position P1(x α ,y α ,z0), based on the receiving array center B(x re ,y re ,z re ), calculate the position P2(x β ,y β ,z0), the minimum constraint problem constructed is:

[0019]

[0020] Among them, α is the projection angle of the transmitting cone, and β is the projection angle of the receiving cone.

[0021] In an improved multi-beam bathymetric non-concentric array homing method, step 3 includes: using the initial value of the transmitting cone projection angle α0 and the initial value of the receiving cone projection angle β0, using Newton's method and differential calculation to solve the optimal solution α of the transmitting cone projection angle α and the receiving cone projection angle β in the constructed minimum constraint problem. * and β * , use the following formula to assign z0 to a certain water depth value z pCalculate the starting launch water depth z tr To the isobath where z0 is and the initial receiving water depth z re The two-way propagation time t(z0) of the acoustic signal to the isobath at z0 is:

[0022] t(z p )=T1(α * ,z p )+T2(β * ,z p )

[0023] Among them, T1(α * ,z p ) is the initial launch water depth z tr To a certain water depth z p The propagation time of the isobath, T2(β * ,z p ) is the initial receiving water depth z re to z p The propagation time of the isobath, t(z p ) is the initial launch water depth z tr to z p The isobath and the initial receiving water depth z re to z p The two-way propagation time of the acoustic signal at the isobath.

[0024] In an improved multi-beam bathymetric non-concentric array homing method, step 4 includes: correcting the water depth value using the following formula:

[0025] z1=z0+c(z0)·cosψ·(tt-t(z0)) / 2

[0026] where ψ = arcsin(c(z0)·sinθ α* / c tr ) is the grazing angle of the emitted sound line on the isobath where the initial water depth value z0 is located, z1 is the corrected water depth value, and c(z0) is the sound velocity at the initial water depth value z0.

[0027] In another aspect, the present invention further provides a system based on the above-mentioned multi-beam bathymetric non-concentric array homing method, comprising:

[0028] An initial value determination module is used to determine the initial value of water depth, the initial value of the projection angle of the transmitting cone, the initial value of the projection angle of the receiving cone, the actual two-way propagation time of the acoustic signal, and the threshold value of the set propagation time error;

[0029] The minimum constraint problem construction module is used to construct the minimum constraint problem for the initial value of the water depth by changing the projection angle of the transmitting cone and the projection angle of the receiving cone so that the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath at a certain underwater water depth value;

[0030] A solution module is used to solve the optimal solution of the emission cone projection angle and the receiving cone projection angle in the constructed minimum constraint problem by using the initial value of the emission cone projection angle and the initial value of the receiving cone projection angle, obtain the intersection position of the emission surface and the receiving surface at the isobath where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal; and

[0031] The correction module is used to iteratively correct the water depth value, update the initial water depth value using the corrected water depth value, update the initial value of the transmitting cone projection angle and the initial value of the receiving cone projection angle using the optimal solution of the transmitting cone projection angle and the optimal solution of the receiving cone projection angle, and trigger the minimum constraint problem construction module until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold.

[0032] Compared with the prior art, the advantages of the present invention are:

[0033] 1. According to the distance function of the projection angle of the transmitting cone and the projection angle of the receiving cone, the minimum constraint problem is established to obtain the intersection of the transmitting surface and the receiving surface at a certain depth value underwater and the corresponding two-way propagation time of the acoustic signal, and the theoretical model is more accurate;

[0034] 2. According to the synthetic beam vector, the calculation method of the initial value of water depth, the initial value of the projection angle of the transmitting cone, and the initial value of the projection angle of the receiving cone is given. The minimum constraint problem under the water depth is solved by Newton's method and differential calculation to achieve efficient calculation of the algorithm;

[0035] 3. The propagation time error limit and the iterative correction method of the water depth of the unknown sounding point are given, so that the algorithm converges quickly while ensuring the high accuracy of the homing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of a multi-beam bathymetric non-concentric array homing method according to Embodiment 1 of the present invention;

[0037] Figure 2 is a schematic diagram of a minimum constraint problem established in Example 2 of the present invention;

[0038] Figure 3 is a flow chart of a multi-beam bathymetric non-concentric array homing method according to embodiment 2 of the present invention;

[0039] Figure 4 It is a schematic diagram of the structure of a multi-beam depth sounding non-concentric array homing device according to Example 3 of the present invention. DETAILED DESCRIPTION

[0040] The present invention provides a multi-beam bathymetric non-concentric array homing method and system, which establishes a minimum constraint problem, solves the minimum constraint problem under a given water depth, obtains the intersection of the transmitting and receiving surfaces and the corresponding two-way propagation time of the acoustic signal, and then iteratively corrects the position of the bathymetric point according to the actual two-way propagation time of the acoustic signal.

[0041] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0042] Example 1

[0043] like Figure 1 As shown, it is a flow chart of a multi-beam depth sounding non-concentric array homing method according to an embodiment of the present invention, comprising:

[0044] Step 1: Determine the initial value of water depth, the initial value of the projection angle of the transmitting cone, the initial value of the projection angle of the receiving cone, the actual two-way propagation time of the acoustic signal, and the threshold value of the set propagation time error;

[0045] Step 2: For the initial value of water depth, by changing the projection angle of the transmitting cone and the projection angle of the receiving cone, the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath at a certain water depth value underwater, and the minimum constraint problem is constructed;

[0046] Specifically, the minimum constraint problem is based on the transmitting beam angle, receiving beam angle, hull position, attitude, etc., to construct the transmitting surface and receiving surface, and to calculate the distance between the two intersection points of the transmitting and receiving sound lines at a certain water depth value in the water depth plane as a function of the transmitting cone projection angle and the receiving cone projection angle. The following steps 2-1 to 2-5 may be included:

[0047] Step 2-1: Under the initial value of the transmission cone projection angle α0, the transmission beam angle and the angle parameter of the hull at the transmission time are used to calculate the transmission beam vector, and under the initial value of the reception cone projection angle β0, the reception beam angle and the angle parameter of the hull at the reception time are used to calculate the reception beam vector;

[0048] Step 2-2: Calculate the grazing angle of the transmitting beam vector corresponding to the starting point of the transmitting sound line and the grazing angle of the receiving beam vector corresponding to the starting point of the receiving sound line;

[0049] Step 2-3: Based on the above two grazing angles, calculate the horizontal propagation distance and propagation time of the transmitted sound line corresponding to the transmitting beam vector from the water depth of the transmitting starting point to the initial water depth, and the horizontal propagation distance and propagation time of the received sound line corresponding to the receiving beam vector from the water depth of the receiving starting point to the initial water depth;

[0050] Step 2-4: Calculate the position of the transmitted sound line on the isobath where the initial water depth z0 is located by using the position of the transmitting starting point and the horizontal propagation distance from the water depth at the transmitting starting point to the initial water depth z0, and calculate the position of the received sound line on the isobath where the initial water depth z0 is located by using the position of the receiving starting point and the horizontal propagation distance from the water depth at the receiving starting point to the initial water depth z0;

[0051] Step 2-5: Calculate the distance between the transmitting and receiving sound lines at the isobath where the initial water depth value is located, obtain the distance function of the transmitting cone projection angle and the receiving cone projection angle, and establish the minimum constraint problem of the transmitting cone projection angle and the receiving cone projection angle based on the distance function.

[0052] Step 3: Using the initial values ​​of the projection angle of the transmitting cone and the initial values ​​of the projection angle of the receiving cone, the optimal solution of the projection angle of the transmitting cone and the projection angle of the receiving cone in the constructed minimum constraint problem is solved to obtain the intersection position of the transmitting surface and the receiving surface at the isobath where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal;

[0053] Specifically, the minimum constraint problem under different water depths can be solved by Newton's method and differential calculation, or by optimization algorithms such as gradient descent method, steepest descent method, Gauss-Newton method, LM method, quasi-Newton method and differential calculation.

[0054] The embodiment of the present invention uses Newton's method and differential calculation to solve the minimum constraint problem under different water depths. The specific implementation may include the following steps 3-1 and 3-2:

[0055] Step 3-1: Calculate the synthetic beam vector using the transmitting beam angle, receiving beam angle, and hull attitude angle, and calculate the initial value of the water depth z0, the initial value of the transmitting cone projection angle α0, and the initial value of the receiving cone projection angle β0;

[0056] Step 3-2: Using α0 and β0, solve the minimum constraint problem under the initial value of water depth z0 through Newton's method and differential calculation, and obtain the optimal solution of α0 and β0 * and β * , and then get the intersection of the transmitting surface and the receiving surface at the initial water depth z0, and add the propagation time of the transmitting sound line corresponding to the transmitting beam vector from the water depth of the transmitting starting point to the initial water depth value and the propagation time of the receiving sound line corresponding to the receiving beam vector from the water depth of the receiving starting point to the initial water depth value to obtain the two-way propagation time of the acoustic signal.

[0057] Step 4: Iteratively correct the water depth value, use the corrected water depth value to update the initial water depth value, and use the optimal solution of the transmitting cone projection angle and the optimal solution of the receiving cone projection angle to update the initial value of the transmitting cone projection angle and the initial value of the receiving cone projection angle, until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold.

[0058] In the solution of the embodiment of the present invention, a minimum constraint problem is established through a distance function to solve the intersection of the transmitting surface and the receiving surface and the corresponding two-way propagation time of the acoustic signal at a given water depth. The problem of solving the intersection of two complex surfaces is converted into a minimum constraint problem of solving the projection angle of the transmitting cone and the projection angle of the transmitting cone. The minimum constraint problem can be quickly solved by Newton's method and differential calculation. The model is accurate and easier to understand, and high-precision and fast non-concentric array homing calculation is realized.

[0059] In addition, the present invention calculates the initial value of water depth, the initial value of the transmission cone projection angle and the initial value of the reception cone projection angle by synthesizing the beam vector, and corrects the water depth of the sounding point according to the actual two-way propagation time of the acoustic signal, thereby achieving rapid convergence of the algorithm.

[0060] Example 2

[0061] This embodiment 2 provides a detailed implementation scheme, which is divided into four parts: the first part establishes the minimum constraint problem, the second part provides a method to solve the minimum constraint problem, the third part calculates the initial value by synthesizing the beam vector, and the fourth part gives a detailed algorithm flow and iterative calculation method.

[0062] Part I: Setting up the Minimum Constraint Problem

[0063] The transmitting cone surface has the center of the transmitting array as its vertex and the positive direction of the long axis of the transmitting array as its axis. The semi-vertex angle of the transmitting cone surface is the transmitting beam angle. The vector V1 in any direction on the transmitting cone surface without sound line bending and attitude rotation can be expressed by formula (1).

[0064] V1=[cosθ tr cosα·sinθ tr sinα·sinθ tr ] Τ (1)

[0065] Among them, θ tr is the transmitting beam angle, the positive direction of the transmitting array long axis is X1=[1 0 0] Τ , α is the projection angle of the emission cone, ranging from 0 to 2π.

[0066] After attitude rotation, the transmit beam vector V is calculated by formula (2): tr .

[0067] V tr =Γ1·V1 (2)

[0068]

[0069] Among them, φ tr , Ptr , R tr It is the bow angle, pitch angle and roll angle of the ship at the moment of launch.

[0070] V is calculated by formula (4): tr The grazing angle θ corresponding to the starting point of the emitted sound line α .

[0071] θ α =arccos(V tr ·Z1) (4)

[0072] Where · is the inner product of the vector, Z1=[0 0 -1] Τ for z Negative axis direction.

[0073] Transmit beam vector V tr The corresponding transmitted sound line is from the initial transmitting water depth z tr To water depth p The horizontal propagation distance X1(α,z p ) and propagation time T1(α,z p ) is calculated by formulas (5) and (6), where the water depth z p It is a certain water depth value.

[0074]

[0075] Among them, c tr is the water depth z tr The speed of sound at the point, c(z) is the water depth z The speed of sound at .

[0076] The starting point of the transmitted sound line is located at the center of the transmitting array A(x tr ,y tr ,z tr ), then the emitted sound line is at the water depth z p The position P1(x α ,y α ,z p ) is calculated by formula (7).

[0077]

[0078] in, V tr The angle of the projection on the xOy plane rotated clockwise to the positive direction of the x-axis, ranging from 0 to 2π.

[0079] The receiving cone surface has the center of the receiving array as its vertex and the positive direction of the long axis of the receiving array as its axis. The semi-vertex angle of the receiving cone surface is the receiving beam angle. The vector V2 in any direction on the receiving cone surface without sound line bending and attitude rotation can be expressed by formula (8).

[0080] V2=[cosβ·sinθ re cosθ re sinβ·sinθ re ] Τ (8)

[0081] Among them, θ re is the receiving beam angle, the positive direction of the long axis of the receiving array is Y1=[0 1 0] Τ , β is the receiving cone projection angle, ranging from 0 to 2π.

[0082] After attitude rotation, the receiving beam vector V is calculated by formula (9): re .

[0083] V re =Γ2·V2 (9)

[0084]

[0085] Among them, φ re , P re , R re It is the bow angle, pitch angle and roll angle of the ship at the moment of reception.

[0086] V is calculated by formula (11): re The grazing angle θ corresponding to the starting point of the received sound line β .

[0087] θ β =arccos(V re ·Z1) (11)

[0088] Receive beam vector V re The corresponding receiving sound line starts from the starting receiving water depth z re To water depth p The horizontal propagation distance X2(β,z p ) and propagation time T2(β,z p ) is calculated by formulas (12) and (13).

[0089]

[0090] Among them, c re is the water depth z re The speed of sound at .

[0091] The starting point of the receiving sound line is located at the center of the receiving array B (x re ,y re ,z re ), then the receiving sound line is at the water depth z p The position P2(x β,y β ,z p ) is calculated by formula (14).

[0092]

[0093] in, V re The angle of the projection on the xOy plane rotated clockwise to the positive direction of the x-axis, ranging from 0 to 2π.

[0094] By changing the values ​​of α and β, the sound rays in different directions of the transmitting and receiving surfaces can be obtained at the depth z. p When P1 and P2 are at the same position, the transmission and receiving surfaces at the water depth z can be obtained. p The intersection point P0 of the transmitting and receiving surfaces can be obtained by establishing the minimum constraint problem (15) to solve the intersection point of the transmitting and receiving surfaces. The schematic diagram of the minimum constraint problem established is as follows: Figure 2 As shown, Figure 2 Lieutenant General Water Depth p The plane parallel to the plane formed by the x-axis and the y-axis is called the isobath z p .

[0095]

[0096] Solve the above minimum constraint problem and get the optimal solution (α * ,β * ), then we can get the transmitting and receiving surfaces at the water depth z p The intersection point P0 corresponds to the two-way propagation time t(z p ) is calculated by formula (16).

[0097] t(z p )=T1(α * ,z p )+T2(β * ,z p ) (16)

[0098] Among them, T1(α * ,z p ) is the initial launch water depth z tr To a certain water depth z p The propagation time of the isobath, T2(β * ,z p ) is the initial receiving water depth z re to z p The propagation time of the isobath, t(z p ) is the initial launch water depth z tr to z p The isobath and the initial receiving water depth z reto z p The two-way propagation time of the acoustic signal at the depth contour.

[0099] Part II: Solving the Minimum Constraint Problem

[0100] For the minimum constraint problem (15), Newton's method is used for iterative solution. The parameters are updated according to formula (17) in each iteration. The partial derivatives and Hessian matrix of f3(α, β) are calculated by numerical difference according to formula (19) and formula (20).

[0101] w n+1 =w n -H -1 ·g (17)

[0102]

[0103]

[0104] Among them, w n+1 is the parameter updated in the n+1th iteration, w n is the parameter updated in the nth iteration of w, w0 is the initial value of the input calculated by Newton's method; σ α , σ β is the difference step size.

[0105] Part 3: Calculating initial values

[0106] The initial value of water depth is obtained by tracing the synthetic beam vector according to half of the actual two-way propagation time of the acoustic signal. Assuming that the center of the transmitting array and the center of the receiving array are located at the same position, the equation group (21) related to the synthetic beam vector is obtained through the transmitting beam angle, the receiving beam angle, and the three-dimensional attitude angle of the hull.

[0107]

[0108] Among them, V c =[x c y c z c ] Τ is the synthetic beam vector.

[0109] According to the three-dimensional attitude angle of the ship, the positive direction of the long axis of the transmitting array after attitude rotation η1 and the positive direction of the long axis of the receiving array after attitude rotation η2 can be calculated by formula (22).

[0110]

[0111] Substitute formula (22) into equation group (21) and simplify to obtain equation group (23).

[0112]

[0113] The first and second terms of the simultaneous equation system (23) can be obtained as x c ,y c About z c Substituting the expression into the third term of equation (23) yields the following equation about z c Solving the equation gives z c After calculating x c ,y c , and obtain the synthetic beam vector V c .

[0114] Calculate V by formula (24) c The grazing angle θ corresponding to the starting point of the sound line c .

[0115] θ c =arccos(V c ·Z1) (24)

[0116] The initial value of water depth z0 is obtained by ray tracing based on half of the actual two-way propagation time tt of the acoustic signal, so that it satisfies formula (25).

[0117]

[0118] The initial value of the projection angle of the transmitting cone α0 and the initial value of the projection angle of the receiving cone β0 are calculated by formulas (26) and (27).

[0119]

[0120] Among them, [x c1 y c1 z c1 ] Τ =Γ1 Τ ·V c is the composite beam vector V c The vector without the ship attitude correction at the time of launch, [x c2 y c2 z c2 ] Τ =Γ2 Τ ·V c is the composite beam vector V c The vector without the correction of the ship's attitude at the time of reception.

[0121] Part 4: Iterative correction of the position of the sounding point

[0122] like Figure 3 As shown in FIG. 1 , it is a flowchart of iteratively correcting the location of the sounding point, including the following steps (a) to (d):

[0123] (a) Input parameter θ tr ,θ re , tt, etc., given the threshold ε of the propagation time error t , calculate the synthetic beam vector V c , calculate the initial value of water depth z0, the initial value of transmitting cone projection angle α0, and the initial value of receiving cone projection angle β0.

[0124] (b) Construct the minimum constraint problem (15) at water depth z0, and use Newton's method to calculate the optimal solution α of the minimum constraint problem using formula (17) with α0 and β0 as initial values. * , β * , we obtain the intersection point P0 of the transmitting and receiving surfaces at the water depth z0, and calculate the corresponding two-way propagation time t(z0) of the acoustic signal by formula (16).

[0125] (c) If |tt-t(z0)|<ε t , go to step (d); otherwise, the water depth value is corrected by formula (28), and the correction value is equal to the initial value plus the water depth distance propagated in the tangent direction of the transmitted sound line in the remaining time, and the parameter α0=α is updated. * , β0=β * , z0=z1, go to step (b).

[0126] z1=z0+c(z0)·cosψ·(tt-t(z0)) / 2 (28)

[0127] in, is the grazing angle of the transmitted sound line at the water depth z0, z1 is the corrected water depth value, and c(z0) is the sound speed at the initial water depth z0;

[0128] The above formula (28), that is, the correction value, is equal to the initial value of the water depth plus the water depth distance propagated in the tangent direction of the transmitted sound line during the remaining time.

[0129] (d) Output the sounding point P0.

[0130] Example 3

[0131] like Figure 4 As shown, it is a multi-beam depth sounding non-concentric array homing device according to embodiment 3 of the present invention, comprising:

[0132] An initial value determination module 41 is used to determine an initial value of water depth, an initial value of a projection angle of a transmitting cone, an initial value of a projection angle of a receiving cone, an actual two-way propagation time of an acoustic signal, and a threshold value of a set propagation time error;

[0133] The minimum constraint problem construction module 42 is used to construct the minimum constraint problem for the initial value of the water depth, based on changing the projection angle of the transmitting cone and the projection angle of the receiving cone so that the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath where a certain underwater water depth value is located;

[0134] A solution module 43 is used to solve the optimal solution of the emission cone projection angle and the receiving cone projection angle in the constructed minimum constraint problem by using the initial value of the emission cone projection angle and the initial value of the receiving cone projection angle, obtain the intersection position of the emission surface and the receiving surface at the isobath where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal; and

[0135] The correction module 44 is used to iteratively correct the water depth value, and use the optimal solution of the transmission cone projection angle and the optimal solution of the reception cone projection angle to update the initial value of the transmission cone projection angle and the initial value of the reception cone projection angle, triggering the minimum constraint problem construction module 42 until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A multi-beam depth sounding non-concentric array homing method, comprising: Step 1: Determine the initial value of water depth, the initial value of the projection angle of the transmitting cone, the initial value of the projection angle of the receiving cone, the actual two-way propagation time of the acoustic signal, and the threshold value of the set propagation time error; Step 2: For the initial value of water depth, by changing the projection angle of the transmitting cone and the projection angle of the receiving cone, the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath at a certain water depth value underwater, and the minimum constraint problem is constructed; Step 3: Using the initial values ​​of the projection angle of the transmitting cone and the initial values ​​of the projection angle of the receiving cone, the optimal solution of the projection angle of the transmitting cone and the projection angle of the receiving cone in the constructed minimum constraint problem is solved to obtain the intersection position of the transmitting surface and the receiving surface at the isobath where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal; Step 4: Iteratively correct the water depth value, use the corrected water depth value to update the initial water depth value, and use the optimal solution of the transmitting cone projection angle and the optimal solution of the receiving cone projection angle to update the initial value of the transmitting cone projection angle and the initial value of the receiving cone projection angle, until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold; The initial value of water depth z0 is determined by: according to The initial value of water depth z0 is obtained by ray tracing, so that it satisfies the following formula: Where tt is the actual two-way propagation time of the acoustic signal, θ c is the composite beam vector V c The grazing angle corresponding to the starting point of the sound line, θ c =arccos(V c ·Z1), Z1=[0 0 -1] Τ for z Negative axis direction, c tr is the initial launch water depth z tr The speed of sound at the depth z, c(z) is the speed of sound at the depth z, V c =[x c y c z c ] Τ , which is obtained by using the transmitting beam angle, receiving beam angle and the three-dimensional attitude angle of the hull.

2. The multi-beam depth sounding non-concentric array homing method according to claim 1, characterized in that: The initial values ​​of the projection angle of the transmitting cone α0 and the projection angle of the receiving cone β0 are determined by the following formula: Among them, [x c1 y c1 z c1 ] Τ =Γ1 Τ ·V c is the composite beam vector V c The vector without the ship attitude correction at the time of launch, [x c2 y c2 z c2 ] Τ =Γ2 Τ ·V c is the composite beam vector V c The vector that has not been corrected by the ship's attitude at the time of reception, Γ1 is the ship's attitude rotation matrix at the time of transmission, and Γ2 is the ship's attitude rotation matrix at the time of reception.

3. The multi-beam bathymetric non-concentric array homing method according to any one of claims 1 to 2, characterized in that: Step 2 includes: based on the starting point of the transmitted sound line being located at the center of the transmitting array A (x tr ,y tr ,z tr ), calculate the position P1(x α ,y α ,z0), based on the receiving array center B(x re ,y re ,z re ), calculate the position P2(x β ,y β ,z0), the minimum constraint problem constructed is: Among them, α is the projection angle of the transmitting cone, and β is the projection angle of the receiving cone.

4. The multi-beam depth sounding non-concentric array homing method according to claim 3, characterized in that: Step 3 includes: using the initial value of the projection angle of the transmitting cone α0 and the initial value of the projection angle of the receiving cone β0, using Newton's method and differential calculation to solve the optimal solution of the projection angle of the transmitting cone α and the projection angle of the receiving cone β in the minimum constraint problem constructed. * and β * , use the following formula to assign z0 to a certain water depth value z p Calculate the starting launch water depth z tr To the isobath where z0 is and the initial receiving water depth z re The two-way propagation time t(z0) of the acoustic signal to the depth equal to z0 is: t(z p )=T1(α * ,z p )+T2(β * ,z p ) Among them, T1(α * ,z p ) is the initial launch water depth z tr To a certain water depth z p The propagation time of the isobath, T2(β * ,z p ) is the initial receiving water depth z re to z p The propagation time of the isobath, t(z p ) is the initial launch water depth z tr to z p The isobath and the initial receiving water depth z re to z p The two-way propagation time of the acoustic signal at the depth contour.

5. The multi-beam depth sounding non-concentric array homing method according to claim 4, characterized in that: Step 4 includes: correcting the water depth value using the following formula: z1=z0+c(z0)·cosψ·(tt-t(z0)) / 2 in, is the grazing angle of the emitted sound ray on the isobath where the initial water depth value z0 is located, z1 is the corrected water depth value, and c(z0) is the sound velocity at the initial water depth value z0.

6. A system based on the multi-beam bathymetric non-concentric array homing method according to claim 1, characterized in that: include: An initial value determination module is used to determine the initial value of water depth, the initial value of the projection angle of the transmitting cone, the initial value of the projection angle of the receiving cone, the actual two-way propagation time of the acoustic signal, and the threshold value of the set propagation time error; The minimum constraint problem construction module is used to construct the minimum constraint problem for the initial value of the water depth by changing the projection angle of the transmitting cone and the projection angle of the receiving cone so that the multi-beam underwater acoustic transmitting surface and the receiving surface can have an intersection on the isobath at a certain underwater water depth value; A solution module is used to solve the optimal solution of the emission cone projection angle and the receiving cone projection angle in the constructed minimum constraint problem by using the initial value of the emission cone projection angle and the initial value of the receiving cone projection angle, obtain the intersection position of the emission surface and the receiving surface on the equal depth surface where the initial value of the water depth is located, and then calculate the two-way propagation time of the acoustic signal; and The correction module is used to iteratively correct the water depth value, update the initial water depth value using the corrected water depth value, update the initial value of the transmitting cone projection angle and the initial value of the receiving cone projection angle using the optimal solution of the transmitting cone projection angle and the optimal solution of the receiving cone projection angle, and trigger the minimum constraint problem construction module until the error between the actual two-way propagation time of the acoustic signal and the calculated two-way propagation time of the acoustic signal is less than the set propagation time error threshold.

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