CN108008348A

CN108008348A - Underwater Wave arrival direction estimating method and device based on adjustable angle even linear array

Info

Publication number: CN108008348A
Application number: CN201711137001.0A
Authority: CN
Inventors: 宁更新; 李晓鹏; 谭纬城; 张军; 冯义志; 季飞
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2017-11-16
Filing date: 2017-11-16
Publication date: 2018-05-08
Anticipated expiration: 2037-11-16
Also published as: CN108008348B; WO2019095912A1

Abstract

The invention discloses a kind of underwater Wave arrival direction estimating method and device based on adjustable angle even linear array, the even linear array that the present invention can be adjusted using two angles, the velocity of sound this variable has been eliminated by the relation between two array angles and direction of arrival angle, so that last operation result is unrelated with the velocity of sound, so as to improve estimated accuracy, simultaneously because two linear array angles are variable, by taking different value to take multiple measurements, error can be preferably eliminated.

Description

Underwater direction of arrival estimation method and device based on adjustable included angle uniform linear array

Technical Field

The invention relates to the technical field of underwater target positioning, in particular to an underwater direction-of-arrival estimation method and device based on an adjustable included angle uniform linear array.

Background

Array signal processing techniques have been widely used in many fields, and one of the basic problems of array signal processing is estimation of the direction of arrival (DOA) of spatial signals. The DOA estimation, namely the spatial spectrum estimation, adopts a processing method that a plurality of sensors are arranged in a noise environment to form an array so as to receive a target signal, then the received signal of the array is processed, and finally the incidence direction of the target signal relative to the array is estimated. The subspace decomposition algorithm is a high-resolution method developed in the 70 th of the 20 th century, can accurately estimate parameters (frequency, direction and the like) of a signal, has ideal performance and higher resolution and estimation precision than the traditional method, and is widely applied to the DOA estimation field. The subspace decomposition algorithm is characterized in that through proper mathematical transformation, the received signals of the array are decomposed into two mutually orthogonal subspaces, namely a signal subspace and a noise subspace, and then respective characteristics of the two subspaces are utilized to carry out DOA estimation. Therefore, the subspace decomposition algorithm can be divided into two types of subspace algorithms, namely a signal subspace algorithm represented by an ESPRIT algorithm based on a subspace rotation invariant technology and a noise subspace algorithm represented by a multiple classification algorithm (MUSIC algorithm). MUSIC belongs to an extremum searching method, and an ESPRIT algorithm belongs to a direct solution method, so that the ESPRIT algorithm does not need to carry out full-space spectrum peak searching, and the operation amount is far smaller than that of the MUSIC algorithm. In addition, the ESPRIT algorithm has the advantages of feasibility and high resolution, so that the ESPRIT algorithm is widely applied to DOA estimation.

However, the existing method for estimating the direction of arrival by using the ESPRIT algorithm has the problem of low accuracy, on one hand, in the process of estimating the DOA by using the ESPRIT algorithm, the propagation speed of a signal in a medium needs to be taken as a known parameter, and in an underwater environment, the sound speed is related to a plurality of environmental factors and is a constantly changing parameter, so that a large error is generated when a fixed sound speed parameter is used for estimating the underwater DOA. On the other hand, the linear arrays used for the existing direction of arrival estimation are all fixed included angles, and in the actual measurement process, the fixed included angles can only be measured for many times, so that the estimation precision cannot be effectively improved.

Disclosure of Invention

The invention mainly aims to overcome the defects of the ESPRIT algorithm and provide an underwater direction-of-arrival estimation method based on two adjustable included angle uniform linear arrays, wherein the two adjustable included angle uniform linear arrays are used as receiving arrays, the propagation speed of signals in a medium is eliminated in the algorithm process, and higher measurement accuracy is obtained by multiple groups of measurements of different included angles compared with the existing DOA method.

The invention also aims to provide an underwater direction-of-arrival estimation device based on the adjustable included angle uniform linear array, which can set a plurality of different linear array included angle values for measurement.

The purpose of the invention is realized by the following technical scheme:

an underwater direction-of-arrival estimation method based on an adjustable included angle uniform linear array comprises the following steps:

the method comprises the following steps: establishing a linear array model with an adjustable included angle;

placing two pieces of water with an included angle of α_nThe two uniform linear arrays with adjustable included angles are provided with M array elements, and the distance between the array elements is d; k narrow-band target sound sources are S respectively₁,S₂,…,S_KThe included angle between the incident direction of the sound wave and the positive axis direction of the horizontal uniform linear array is β E (0, Pi);

step two: establishing signal receiving models of two uniform linear arrays;

when the included angle of the linear array is α_nIn time, the direction angles of the K narrow-band target sound sources corresponding to the horizontal linear arrays are respectively theta_nx1,θ_nx2,...,θ_nxKThe direction angles corresponding to the oblique linear arrays are respectively theta_ny1,θ_ny2,...,θ_nyK(ii) a Taking the first array element as a reference point, the signal received by the first array element at the time t is:

wherein s is_i(t) denotes the ith source signal, n₁(t) represents noise on the first array element;

the received signal satisfies the narrow-band condition, that is, when the signal delay is much less than the reciprocal of the bandwidth, the delay action is equivalent to generating a phase shift to the baseband signal, and then the signal received by the mth array element at the same time is:

wherein λ_iRepresenting the wavelength of the sound wave reflected back from the ith target source, n_m(t) represents noise on the mth array element; arranging the received signals of each array element into a column vector form, so that the signals received by the whole horizontal linear arrayCan be represented by the following vector equation:

X(t)＝AS(t)+N(t) (1)

wherein,a matrix of M × K steering vectors, X (t) ═ x₁(t),x₂(t),…,x_M(t)]^TFor a received signal matrix of M × 1, s (t) ═ s₁(t),s₂(t),…,s_K(t)]^TA matrix of K × 1 source signals, n (t) ═ n₁(t),n₂(t),…,n_M(t)]^TIs an mx 1 noise matrix. In the same way, a signal receiving model of the inclined uniform linear array can be obtained;

step three: establishing a uniform linear array subarray model, and deducing a rotation operator phi_xAnd phi_yAn expression;

dividing M array elements in the horizontal linear array into two subarrays Z with translation vector d_hxAnd Z_hy(ii) a Sub-array Z_hxThe array consists of the first to M-1 array elements of a horizontal array, and comprises the following components:

x_h1(t)＝x₁(t),x_h2(t)＝x₂(t),…,x_h(M-1)(t)＝x_M-1(t)

wherein x is_h1(t),x_h2(t),…,x_h(M-1)(t) are respectively subarrays Z_hxThe signals received by the first array element to the M-1 array element;

sub-array Z_hyThe second to Mth array elements of the horizontal array are composed of:

y_h1(t)＝x₂(t),y_h2(t)＝x₃(t),…,y_h(M-1)(t)＝x_M(t)

wherein, y_h1(t),y_h2(t),…,y_h(M-1)(t) are respectively subarrays Z_hyThe signals received by the first array element to the M-1 array element;

then the received signals of the m-th array element in the two sub-arrays are respectively:

whereinn_hxm(t) and n_hym(t) are each subarrays Z_hxAnd Z_hyAdditive noise of the upper m-th array element, the above formula is written as a vector:

X_h(t)＝AS(t)+N_hx(t)

Y_h(t)＝AΦ_xS(t)+N_hy(t)

wherein the matrix phi_xA diagonal matrix of K x K, which is a sub-matrix Z_hxAnd Z_hyThe diagonal elements of the unitary matrix, also called the rotation operator, contain phase delay information of wave fronts of K signals between any matrix element pair, and are expressed as:

according to the steps, the inclined uniform linear array can be divided into two sub-arrays Z_vxAnd Z_vyObtaining a received signal X_v(t) and Y_v(t), thereby deriving the rotation operator as:

step four: establishing a rotation operator phi_x、Φ_yAnd theta_nxi、θ_nyiThe relationship between;

step five: establishing a relation between two direction angles when the sound wave signals are incident from different areas;

step six: for matrix phi_xSum matrix Φ_yThe diagonal elements on the upper board are paired;

step seven: determining theta from the pairing result_nxiThe size of (2).

Preferably, the step four specifically includes:

X_hthe covariance matrix of (t) can be expressed as:

R_hxx＝E[X_h(t)X_h ^H(t)]＝AR_ssA^H+σ²I

wherein R is_ss＝E{S(t)S^H(t) }, which is a source part covariance matrix;

X_h(t) and Y_hThe cross-covariance matrix of (t) is:

R_hxy＝E{X_h(t)Y_h ^H(t)}＝AR_ssΦ_x ^HA^H+σ²Z

performing eigenvalue decomposition on the covariance matrix of the matrix to obtain the minimum eigenvalue sigma²Using σ²A matrix beam C can be obtained_hxx,C_hxyIn which C is_hxx＝R_hxx-σ²I＝AR_ssA^H，C_hxy＝R_hxy-σ²Z＝AR_ssΦ_x ^HA^H(ii) a Computing a matrix Beam { C_hxx,C_hxyDecomposing the generalized eigenvalue of the method to obtain a non-zero eigenvalue lambda_x1,λ_x2,…,λ_xKThey correspond to the matrix phi one by one_xThe elements on the diagonal line, but the correspondence is not determined, so can be written by equation (2):

wherein phi_xiIs a matrix phi_xUpper diagonal element, and phi_xi∈{λ_x1,λ_x2,…,λ_xK},i＝1,2,…,K；

According to the steps, two covariance matrixes R of the inclined uniform array can be obtained_vxxAnd R_vxyThen to the matrix beam { C_vxx,C_vxyResolving the eigenvalue to obtain an eigenvalue lambda_y1,λ_y2,…,λ_yKThey are also in one-to-one correspondence with the matrix phi_yThe above diagonal elements, but the corresponding relationship is also uncertain, and can be written by formula (3):

wherein phi_yiIs a matrix phi_yUpper diagonal element, and phi_yi∈{λ_y1,λ_y2,…,λ_yK},i＝1,2,…,K。

Preferably, the step five specifically comprises:

according to linear array included angle α_nAnd the included angle β between the incident direction of the sound wave and the positive axis direction of the x axis sets the incident area of the sound wave signal to be 4 when β epsilon (0, α)_n) When the acoustic signal is in the area 1, β E (α)_nπ/2), the acoustic signal is incident for region 2, when β ∈ (π/2, π/2+ α)_n) When the acoustic wave signal is incident in the area 3, β epsilon (pi/2 + α)_nAnd pi), the acoustic signal is incident in the area 4;

(1) when an acoustic wave is incident from the region 1, θ_1iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_1jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_1i+θ_1j＝π-α_n(ii) a Because the array signal on the x-axis is referenced to the array element in the most negative direction of the x-axis, and the subarray Z_hxAlso in subarray Z_hySo that when an acoustic wave is incident from region 1, the reference array element is the one that received the signal the latest, sub-array Z_hxThe array element in (1) is also larger than the subarray Z_hyThe corresponding array element in the array receives the signal late, so that the time delay parameter tau is less than 0So there is theta at this time_nxi＝-θ_1iFor the same reason have theta_nyi＝-θ_1j(ii) a In conclusion, it can be obtained that:

θ_nyi＝-θ_nxi+α_n-π (6)

(2) when the acoustic wave is incident from the region 2, θ_2iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_2jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_2j-θ_2i＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝-θ_2i，θ_nyi＝-θ_2jIn summary, the following can be obtained:

θ_nyi＝θ_nxi-α_n(7)

(3) when the acoustic wave is incident from the region 3, θ_3iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_3jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_3i+θ_3j＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝θ_3i，θ_nyi＝-θ_3jIn conclusion, the following can be obtained:

θ_nyi＝θ_nxi-α_n

(4) when the acoustic wave is incident from the region 4, θ_4iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_4jFor sound wave incidentThe angle between the direction and the normal of the tilted linear array is theta_4i-θ_4j＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝θ_4i，θ_nyi＝θ_4jIn conclusion, the following can be obtained:

θ_nyi＝θ_nxi-α_n

from equations (6) and (7), we can obtain:

sinθ_nyi＝sin(θ_nxi-α_n) (8)

substituting equation (8) into equation (5) then there is:

preferably, the sixth step specifically comprises:

as can be seen from the equations (4) and (9), if pairing is successful, the following equation holds:

will arg (lambda)_x1),arg(λ_x2),…,arg(λ_xK) Arranging the sequences from large to small according to respective square size sequences to obtain a sequence H; will arg (lambda)_y1),arg(λ_y2),…,arg(λ_yK) Arranging the sequences from small to large according to respective square size sequences to obtain a sequence V; thus, there are:

wherein h is_iIs the ith element in the sequence H; v. of_iIs the ith element in the sequence V.

Preferably, in step seven,

preferably, the angle α between two uniform linear arrays is changed_nN1, 2,.. multidot.n, repeating steps one to seven, and α for different linear array angles_nCalculating the corresponding direction of arrival angle by formula (12), and averaging the N results to obtain the final result theta_xi,i＝1,2,...,K。

An underwater direction-of-arrival estimation device based on an adjustable included angle uniform linear array comprises a data processing and control module, an angle control module, a transmitting module, a receiving module, an output module and a power supply module; the power module is connected with the data processing and control module, the angle control module, the transmitting module, the receiving module and the output module and can supply power to the modules;

the data processing and control module is the core part of the whole device, and all other modules are directly connected with the data processing and control module; it can control the transmitting module to make the transmitting module transmit the appointed signal; the angle control module can be controlled to enable the included angle of the two uniform linear arrays to be converted to a set value; and the signal transmitted by the receiving module can be processed, the direction of arrival angle is calculated, and the result is transmitted to the transmitting module.

Preferably, the data processing and control module is composed of a pair of A/D, D/A converters and a processor.

Preferably, the angle control module comprises a stepping motor and a driving circuit, and is used for controlling an included angle between the two linear arrays; the stepping motor is an open-loop control motor which converts an electric pulse signal into angular displacement or linear displacement, when the driving circuit receives a pulse signal, the driving circuit drives the stepping motor to rotate for a fixed angle according to a set direction, and a desired angle value can be achieved by enabling the data processing and control module to emit a certain number of pulse signals.

Preferably, the receiving module comprises two ultrasonic receiving probe arrays, and the included angle between the two arrays is variable and can be adjusted through the angle control module.

Specifically, the horizontal array L1 and the stepping motor are fixed together, the array L2 is installed on the stepping motor and ensures that the array L1 and the array L2 are on the same plane, and the array L2 can be driven by the stepping motor to rotate, so that the purpose of adjusting the included angle of the two arrays is achieved.

Specifically, a fixing bracket is arranged at the tail end of the array L1 and is made of plastic; the stepper motor stator is attached to this bracket and the stepper motor rotor is attached to the array L2.

Preferably, the transmitting module includes an impedance matching circuit and an ultrasonic transmitting probe.

Preferably, the output module comprises a USB interface and a display, and is capable of providing human-computer interaction, outputting the processed data in the data processing and control module to an external device through the USB interface or displaying the processed data on the display.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. compared with the method for estimating the direction of arrival of the underwater target by utilizing the traditional ESPRIT algorithm, the method has higher practicability and higher estimation accuracy. The traditional ESPRIT algorithm usually assumes that the sound velocity is a constant, and in a real complex underwater environment, the sound velocity is often constantly changing, which causes a large error if calculated as a constant. The invention adopts the two even linear arrays with adjustable included angles, eliminates the variable of the sound velocity through the relationship between the included angles of the two arrays and the direction of arrival angle, and ensures that the final operation result is irrelevant to the sound velocity, thereby improving the estimation precision.

2. The invention improves the traditional ESPRIT algorithm, simultaneously reserves the advantage of high resolution of the ESPRIT algorithm, does not excessively increase the computation amount and complexity of the improved algorithm, and ensures the feasibility of the algorithm.

3. The device is improved on the traditional measuring device, uses the uniform linear array with the adjustable included angle, and has strong feasibility and simple installation. In addition, the continuous improvement of the computing processing capacity of modern processors ensures that the chips such as the processors and the like used by the invention have high integration and strong computing capacity, thereby ensuring the feasibility of the invention.

Drawings

FIG. 1 is a block diagram showing a hardware configuration of an apparatus according to an embodiment.

Fig. 2 is a schematic diagram of a receiving module connection.

Fig. 3 is a top view of the receiving module connection.

Fig. 4 is a side view of the receiving module connection.

Fig. 5 is an angle-adjustable uniform linear array model used in the embodiment.

Fig. 6 is a received signal model of a horizontal uniform line array.

Fig. 7 shows an adjustable angle uniform line pattern model when a signal is incident from the area 1.

Fig. 8 shows an adjustable angle uniform line pattern model when a signal is incident from the area 2.

Fig. 9 shows an adjustable angle uniform line pattern model when a signal is incident from the area 3.

Fig. 10 shows an adjustable angle uniform line pattern when a signal is incident from the area 4.

FIG. 11 is a flow chart of an embodiment method.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Example 1

An underwater direction-of-arrival estimation method based on adjustable included angle uniform linear arrays is characterized in that received signals of two linear arrays are processed, and a factor of sound velocity can be eliminated in the direction-of-arrival estimation, so that the influence of underwater sound velocity uncertainty on target positioning accuracy is eliminated. And secondly, because the included angle of the two uniform linear arrays is variable, the included angle can be changed in actual measurement to carry out multiple measurements, and errors are better eliminated.

The method adopts two uniform linear arrays with adjustable included angles, wherein the two linear arrays are provided with M array elements, and the distance between the array elements is d; k narrow-band target sound sources are S respectively₁,S₂,…,S_KThe central frequency is f, the included angle between the incident direction of the sound wave and the positive axis direction of the horizontal uniform linear array is β E (0, Pi), and the method measures the included angle value α of the linear array with different N times_nN1, 2, N and α_nE (0, pi/2), and the specific steps are as follows:

step one, establishing an included angle adjustable uniform linear array model, as shown in figure 5, placing two included angles α in water_nA horizontal uniform line array and an inclined uniform line array, which are respectively arranged as an x-axis and a y-axis, α according to the included angle of the line arrays_nAnd the included angle β between the incident direction of the sound wave and the positive axis direction of the x axis sets the incident area of the sound wave signal to be 4 when β epsilon (0, α)_n) When the acoustic signal is in the area 1, β E (α)_nπ/2), the acoustic signal is incident for region 2, when β ∈ (π/2, π/2+ α)_n) When the acoustic wave signal is incident in the area 3, β epsilon (pi/2 + α)_nAnd pi), the acoustic signal is incident in the area 4;

secondly, establishing a signal receiving model of two uniform linear arrays when the included angle of the linear arrays is α_nIn time, the direction angles of the K narrow-band target sound sources corresponding to the horizontal linear arrays are respectively theta_nx1,θ_nx2,...,θ_nxKThe direction angles corresponding to the oblique linear arrays are respectively theta_ny1,θ_ny2,...,θ_nyK. The model scene of the horizontal uniform linear array is shown in fig. 6. Taking the first array element as a reference point, the signal received by the first array element at the time t is:

wherein s is_i(t) denotes the ith source signal, n₁(t) represents the noise on the first array element.

The received signal satisfies the narrow band condition, i.e. when the signal delay is much less than the reciprocal of the bandwidth, the delay acts as a phase shift to the baseband signal. Then the signal received by the mth array element at the same time is:

wherein λ_iRepresenting the wavelength of the sound wave reflected back from the ith target source, n_m(t) represents the noise on the mth array element. Arranging the received signals of each array element into a column vector form, the signals received by the whole horizontal linear array can be represented by the following vector equation:

X(t)＝AS(t)+N(t) (1)

wherein,a matrix of M × K steering vectors, X (t) ═ x₁(t),x₂(t),…,x_M(t)]^TFor a received signal matrix of M × 1, s (t) ═ s₁(t),s₂(t),…,s_K(t)]^TA matrix of K × 1 source signals, n (t) ═ n₁(t),n₂(t),…,n_M(t)]^TIs an mx 1 noise matrix. And obtaining a signal receiving model of the inclined uniform linear array in the same way.

Step three: and establishing a uniform linear array subarray model, and deducing a rotation operator expression. Dividing M array elements in the horizontal linear array into two subarrays Z with translation vector d_hxAnd Z_hy. Sub-array Z_hxThe array consists of the first to M-1 array elements of a horizontal array, and comprises the following components:

x_h1(t)＝x₁(t),x_h2(t)＝x₂(t),…,x_h(M-1)(t)＝x_M-1(t)

wherein x is_h1(t),x_h2(t),…,x_h(M-1)(t) are respectively subarrays Z_hxThe signals received from the first array element to the M-1 array element.

y_h1(t)＝x₂(t),y_h2(t)＝x₃(t),…,y_h(M-1)(t)＝x_M(t)

wherein, y_h1(t),y_h2(t),…,y_h(M-1)(t) are respectively subarrays Z_hyThe signals received from the first array element to the M-1 array element.

whereinn_hxm(t) and n_hym(t) are each subarrays Z_hxAnd Z_hyAdditive noise of the upper m-th array element. Write the above equation in vector form:

X_h(t)＝AS(t)+N_hx(t)

Y_h(t)＝AΦ_xS(t)+N_hy(t)

step four: establishing a rotation operator phi_xAnd phi_yAnd theta_nxiAnd theta_nyiThe relationship between them. X_hThe covariance matrix of (t) can be expressed as:

R_hxx＝E[X_h(t)X_h ^H(t)]＝AR_ssA^H+σ²I

wherein R is_ss＝E{S(t)S^H(t) }, which is the source part covariance matrix.

X_h(t) and Y_hThe cross-covariance matrix of (t) is:

R_hxy＝E{X_h(t)Y_h ^H(t)}＝AR_ssΦ_x ^HA^H+σ²Z

performing eigenvalue decomposition on the covariance matrix of the matrix to obtain the minimum eigenvalue sigma²Using σ²A matrix beam C can be obtained_hxx,C_hxyIn which C is_hxx＝R_hxx-σ²I＝AR_ssA^H，C_hxy＝R_hxy-σ²Z＝AR_ssΦ_x ^HA^H. Computing a matrix Beam { C_hxx,C_hxyDecomposing the generalized eigenvalue of the method to obtain a non-zero eigenvalue lambda_x1,λ_x2,…,λ_xKThey correspond to the matrix phi one by one_xThe elements on the diagonal line, but the correspondence is not determined, so can be written by equation (2):

wherein phi_xiIs a matrix phi_xUpper diagonal element, and phi_xi∈{λ_x1,λ_x2,…,λ_xK},i＝1,2,…,K。

Step five: the relationship between the two direction angles when the acoustic wave signals are incident from different areas is established.

(1) When an acoustic wave is incident from the region 1, θ is shown in fig. 7_1iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_1jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_1i+θ_1j＝π-α_n. Because the array signal on the x-axis is referenced to the array element in the most negative direction of the x-axis, and the subarray Z_hxAlso in subarray Z_hyIn the negative x-axis direction. So that when an acoustic wave is incident from region 1, the reference array element is the latest received signal, subarray Z_hxThe array element in (1) is also larger than the subarray Z_hyThe corresponding array element in the array receives the signal late, so that the time delay parameter tau is less than 0So there is theta at this time_nxi＝-θ_1iFor the same reason have theta_nyi＝-θ_1j. In conclusion, it can be obtained that:

θ_nyi＝-θ_nxi+α_n-π (6)

(2) when the acoustic wave is incident from the region 2, θ is shown in fig. 8_2iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_2jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_2j-θ_2i＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝-θ_2i，θ_nyi＝-θ_2jIn summary, the following can be obtained:

θ_nyi＝θ_nxi-α_n(7)

(3) when the acoustic wave is incident from the region 3, θ is shown in fig. 9_3iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_3jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_3i+θ_3j＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝θ_3i，θ_nyi＝-θ_3jIn conclusion, the following can be obtained:

θ_nyi＝θ_nxi-α_n

(4) when the acoustic wave is incident from the region 4, θ is shown in fig. 10_4iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_4jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_4i-θ_4j＝α_nAccording to the analytical method used in (1), in which case there is theta_nxi＝θ_4i，θ_nyi＝θ_4jThe same can be concluded

θ_nyi＝θ_nxi-α_n

From equations (6) and (7), we can obtain:

sinθ_nyi＝sin(θ_nxi-α_n) (8)

substituting equation (8) into equation (5) then there is:

step six: for matrix phi_xSum matrix Φ_yUpper diagonal element phi_xiPhi and phi_yiAnd (6) pairing. As can be seen from the equations (4) and (9), if pairing is successful, the following equation holds:

will arg (lambda)_x1),arg(λ_x2),…,arg(λ_xK) Arranging the sequences from large to small according to respective square size sequences to obtain a sequence H; will arg (lambda)_y1),arg(λ_y2),…,arg(λ_yK) The sequences V are arranged from small to large according to the respective square size order. Thus, there are:

Step seven: determining theta from the pairing result_nxiThe size of (2).

From equation (10) it follows:

eighthly, changing the included angle between the two uniform linear arrays α_nN1, 2, repeating steps 1 to 7, α for different line angles_nCalculating the corresponding direction of arrival angle by formula 12, and averaging the N results to obtain the final result theta_xi,i＝1,2,...,K。

According to the algorithm flow, the improved algorithm provided by the embodiment can be used for theta without knowing the sound velocity_xiMaking an accurate estimate of the direction of arrival angle θ, i.e. the speed of sound, can be estimated under uncertainty_xiOvercomes the disadvantages of the traditional ESPRIT algorithm. Meanwhile, the included angle between the two linear arrays is changed to carry out estimation for multiple times and finally the average value is obtained, so that errors can be effectively eliminated.

A flow chart of the above method may be represented by fig. 11.

Example 2

The underwater direction-of-arrival estimation device based on the adjustable included angle uniform linear array, as shown in fig. 1, includes a data processing and control module, an angle control module, a transmitting module, a receiving module, an output module, and a power supply module.

The data processing and control module consists of a pair of A/D, D/A converters and a processor, and is the core part of the whole device, and all other modules are directly connected with the data processing and control module. It can control the transmitting module to make the transmitting module transmit the appointed signal; the angle control module can be controlled to enable the included angle of the two uniform linear arrays to be converted to a set value; and the signal transmitted by the receiving module can be processed, the direction of arrival angle is calculated by the algorithm of the embodiment 1, and then the result is transmitted to the transmitting module.

The angle control module is used for controlling an included angle between the two linear arrays and consists of a stepping motor and a driving circuit. The step motor is an open-loop control motor which converts an electric pulse signal into angular displacement or linear displacement, and when a driving circuit receives a pulse signal, the driving circuit drives the step motor to rotate by a fixed angle in a set direction, namely a step angle. The desired angle value can be reached by having the data processing and control module transmit a certain number of pulse signals.

The receiving module is composed of two ultrasonic receiving probe arrays, the included angle between the two arrays is variable and can be adjusted through the angle control module, as shown in fig. 2, the horizontal array L1 and the stepping motor are fixed together, the array L2 is installed on the stepping motor and ensures that the array L1 and the array L2 are on the same plane, and the array L2 can be driven by the stepping motor to rotate, so that the purpose of adjusting the included angle between the two arrays is achieved. Fig. 3 and 4 show the apparatus in top and side views respectively, and show that there is a fixed bracket at the end of the array L1, which is made of plastic to increase buoyancy because the receiving module will be placed in the water. The stepper motor stator is attached to this bracket and the stepper motor rotor is attached to the array L2. The two arrays can also receive the signal emitted from the target sound source, and then the signal is subjected to A/D conversion and then is transmitted to the processor.

The transmitting module consists of an impedance matching circuit and an ultrasonic transmitting probe, is connected with the processor through a D/A converter and can transmit a specified signal according to an instruction sent by the processor.

The output module consists of a USB interface and a display, and is connected with the data processing and control module and the power supply module. The intelligent control system can provide human-computer interaction, and output the processed data in the data processing and control module to an external device through a USB interface or display the processed data on a display.

The power module consists of a power supply and is connected with the data processing and control module, the angle control module, the transmitting module, the receiving module and the output module. It is able to power these modules.

The main working flow of the device is as follows: in the actual measurement process, according to the signal parameter to be transmitted, the corresponding parameter is input through the data processing and control module, so that the processor generates a corresponding digital signal, and then the digital signal is transmitted to the transmitting module through D/A conversion, and the ultrasonic transmitting probe can generate and transmit the signal required by people. The included angle value between the two linear arrays can be set through the data processing and control module, the processor sends a specific pulse signal to the driving circuit of the angle control module, and then the driving circuit can drive the stepping motor to rotate to a required angle. The receiving array in the receiving module receives the signal reflected from the target sound source, converts the signal into a digital signal through A/D and sends the digital signal to the processor, and then the processor calculates the result according to the provided algorithm. And finally, the data processing and control module transmits the calculation result to an output module, and the output module transmits the result to external equipment through a USB interface or displays the result through a display. The power module supplies power to all other modules.

The device comprises a data processing and controlling module, an angle controlling module, a transmitting module, a receiving module, an output module and a power supply module. The data processing and control module can be realized by a DSP chip (such as a DSP chip of a TI company TMS320VC5509A model), the DSP chip can realize the functions of A/D conversion and D/A conversion, and can realize the rotation operator of the uniform linear array and the calculation of the final direction of arrival; the angle control module comprises a stepping motor and a driving circuit, the model of the stepping motor is HSTM42-1.8-D-26-4-0.4 of Fuxing company, the step angle of the stepping motor is 1.8 degrees, and the driving circuit adopts an ULN2003 chip; the transmitting module uses an ultrasonic transmitting probe; the receiving module uses two uniform linear arrays with adjustable included angles, wherein each array comprises a plurality of ultrasonic receiving probes, the number of the ultrasonic receiving probes is the same, and the two linear arrays are assembled as shown in figure 2; the output module uses a USB interface and an LCD display screen. Fig. 1 is a block diagram of the hardware structure of the apparatus according to the present invention.

The working steps are as follows:

step 1: 5 different linear array included angle values are set, namely N is equal to 5, and the values are respectively 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees. And setting a linear array included angle value in the data processing and control module, and converting the included angle of the two linear arrays into 15 degrees through the angle control module. 4 target sound sources are placed under water, and the included angles between the target sound sources and the normal line of the horizontal array are respectively 30 degrees, 60 degrees, 30 degrees and 60 degrees. The parameters of the transmitting module are set through the data processing and control module, so that the frequency of the transmitting signal is 100kHz, and the pulse length is 5 ms. Setting receiving array parameters, setting the number M of respective array elements of the two uniform linear arrays to be 10, setting the distance d between the array elements to be 5mm, and then setting the first 9 array elements to be one subarray, setting the last 9 array elements to be the other subarray, and setting the distance between the two subarrays to be d.

Step 2: sampling a target sound source signal received by an ultrasonic receiving probe; the signals received by the horizontal uniform array are x respectively_x1(t),x_x2(t),…,x_x8(t) and y_x1(t),y_x2(t),…,y_x8(t) the signals received by the tilt-direction uniform array are x respectively_y1(t),x_y2(t),…,x_y8(t) and y_y1(t),y_y2(t),…,y_y8(t) of (d). Sampling and receiving are carried out for 200 times in total, and the received signals are transmitted to a data acquisition processing and control module for operation processing.

And step 3: the processing steps of the signals in the data acquisition processing and control module are as follows:

1) arranging signals received by a uniform array in the horizontal direction into vector form X_h(t) and Y_h(t), calculating X_h(t) covariance matrix R_hxx＝E[X_h(t)X_h ^H(t)]，X_h(t) and Y_h(t) cross covariance matrix R_hxy＝E{X_h(t)Y_h ^H(t) }. Simultaneously, the signals received by the uniform array in the inclined direction are processed in the same way to obtain R_vxx＝E[X_v(t)X_v ^H(t)]And R_vxy＝E{X_v(t)Y_v ^H(t)}

2) For two covariance matrices R in the horizontal array_hxxAnd R_hxyDecomposing the eigenvalue to obtain the minimum eigenvalue sigma²Thus having C_hxx＝R_hxx-σ²I＝AR_ssA^HAnd C_hxy＝R_hxy-σ²Z＝AR_ssΦ^HA^H. Simultaneously carrying out the same processing on two covariance matrixes in the inclined array to obtain C_vxxAnd C_vxy。

3) Separately compute a matrix bundle { C_hxx,C_hxyAnd { C }_vxx,C_vxyDecomposing the generalized eigenvalue of the lambda to obtain lambda_x1,λ_x2,…,λ_xKAnd λ_y1,λ_y2,…,λ_yK。

4) Will arg (lambda)_x1),arg(λ_x2),…,arg(λ_xK) The sequences H are arranged from large to small according to the respective square size order, and arg (lambda)_y1),arg(λ_y2),…,arg(λ_yK) The sequences V are arranged from small to large according to the respective square size order. Then the ith element H in H_iIs given to arg (phi)_xi) I-th element V in V_iIs given to arg (phi)_yi)。

5) Arg (phi) from matching_xi) And arg (phi)_yi) And finally solving the included angle between the two linear arrays:

and 4, step 4: and storing the calculated direction angle information, and transmitting the direction angle information to an output module to be output to an external device through a USB interface or displayed on an LCD display screen.

And 5: the included angles between the two linear arrays are changed and respectively set to be 30 degrees, 45 degrees, 60 degrees and 75 degrees, the average values are finally obtained according to the results of each calculation, the direction angles estimated according to the algorithm are respectively 30 degrees, 60 degrees, 30 degrees and 60 degrees, the direction angles are the same as the actual angles, the estimation result is correct, and the method and the device are feasible.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The underwater direction-of-arrival estimation method based on the adjustable included angle uniform linear array is characterized by comprising the following steps of:

step two: establishing signal receiving models of two uniform linear arrays;

<mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <munderover> <mo>&Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>s</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>n</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow>

<mrow> <msub> <mi>x</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <munderover> <mo>&Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>s</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j</mi> <mrow> <mo>(</mo> <mi>m</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mfrac> <mrow> <mn>2</mn> <mi>&pi;</mi> </mrow> <msub> <mi>&lambda;</mi> <mi>i</mi> </msub> </mfrac> <msub> <mi>dsin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mi>i</mi> </mrow> </msub> </mrow> </msup> <mo>+</mo> <msub> <mi>n</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <mi>M</mi> </mrow>

wherein λ_iRepresenting the wavelength of the sound wave reflected back from the ith target source, n_m(t) represents noise on the mth array element; arranging the received signals of each array element into a column vector form, the signals received by the whole horizontal linear array can be represented by the following vector equation:

X(t)＝AS(t)+N(t) (1)

wherein,a matrix of M × K steering vectors, X (t) ═ x₁(t),x₂(t),…,x_M(t)]^TFor a received signal matrix of M × 1, s (t) ═ s₁(t),s₂(t),…,s_K(t)]^TA matrix of K × 1 source signals, n (t) ═ n₁(t),n₂(t),…,n_M(t)]^TA noise matrix of mx 1; in the same way, a signal receiving model of the inclined uniform linear array can be obtained;

x_h1(t)＝x₁(t),x_h2(t)＝x₂(t),…,x_h(M-1)(t)＝x_M-1(t)

y_h1(t)＝x₂(t),y_h2(t)＝x₃(t),…,y_h(M-1)(t)＝x_M(t)

<mrow> <msub> <mi>x</mi> <mrow> <mi>h</mi> <mi>m</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <munderover> <mo>&Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>s</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <msub> <mi>a</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>&theta;</mi> <mi>i</mi> </msub> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>n</mi> <mrow> <mi>h</mi> <mi>x</mi> <mi>m</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <mi>M</mi> </mrow>

<mrow> <msub> <mi>y</mi> <mrow> <mi>h</mi> <mi>m</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <munderover> <mo>&Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <msub> <mi>s</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mfrac> <mrow> <mn>2</mn> <mi>&pi;</mi> <mi>d</mi> </mrow> <msub> <mi>&lambda;</mi> <mi>i</mi> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mi>i</mi> </mrow> </msub> </mrow> </msup> <msub> <mi>a</mi> <mi>m</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>&theta;</mi> <mi>i</mi> </msub> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>n</mi> <mrow> <mi>h</mi> <mi>y</mi> <mi>m</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <mi>M</mi> </mrow>

X_h(t)＝AS(t)+N_hx(t)

Y_h(t)＝AΦ_xS(t)+N_hy(t)

<mrow> <msub> <mi>&Phi;</mi> <mi>x</mi> </msub> <mo>=</mo> <mi>d</mi> <mi>i</mi> <mi>a</mi> <mi>g</mi> <mo>{</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mn>1</mn> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mn>1</mn> </mrow> </msub> </mrow> </msup> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mn>2</mn> </mrow> </msub> </mrow> </msup> <mo>,</mo> <mo>...</mo> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mi>K</mi> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mi>k</mi> </mrow> </msub> </mrow> </msup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </mrow>

<mrow> <msub> <mi>&Phi;</mi> <mi>y</mi> </msub> <mo>=</mo> <mi>d</mi> <mi>i</mi> <mi>a</mi> <mi>g</mi> <mo>{</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mn>1</mn> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>y</mi> <mn>1</mn> </mrow> </msub> </mrow> </msup> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>y</mi> <mn>2</mn> </mrow> </msub> </mrow> </msup> <mo>,</mo> <mo>...</mo> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mi>K</mi> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>y</mi> <mi>k</mi> </mrow> </msub> </mrow> </msup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow>

step seven: determining theta from the pairing result_nxiThe size of (2).

2. The underwater direction-of-arrival estimation method based on the adjustable included angle uniform linear array according to claim 1, characterized in that the fourth step specifically comprises:

X_hthe covariance matrix of (t) can be expressed as:

R_hxx＝E[X_h(t)X_h ^H(t)]＝AR_ssA^H+σ²I

wherein R is_ss＝E{S(t)S^H(t) }, which is a source part covariance matrix;

X_h(t) and Y_hThe cross-covariance matrix of (t) is:

R_hxy＝E{X_h(t)Y_h ^H(t)}＝AR_ssΦ_x ^HA^H+σ²Z

<mrow> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mn>1</mn> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>x</mi> <mi>i</mi> </mrow> </msub> </mrow> </msup> <mo>=</mo> <msub> <mi>&phi;</mi> <mrow> <mi>x</mi> <mi>i</mi> </mrow> </msub> <mo>,</mo> <mi>i</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <mi>K</mi> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>4</mn> <mo>)</mo> </mrow> </mrow>

<mrow> <msup> <mi>e</mi> <mrow> <mi>j</mi> <mn>2</mn> <mi>&pi;</mi> <mfrac> <mi>d</mi> <msub> <mi>&lambda;</mi> <mi>i</mi> </msub> </mfrac> <msub> <mi>sin&theta;</mi> <mrow> <mi>n</mi> <mi>y</mi> <mi>i</mi> </mrow> </msub> </mrow> </msup> <mo>=</mo> <msub> <mi>&phi;</mi> <mrow> <mi>y</mi> <mi>i</mi> </mrow> </msub> <mo>,</mo> <mi>i</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <mi>K</mi> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>5</mn> <mo>)</mo> </mrow> </mrow>

3. The method for estimating the underwater direction of arrival of the uniform linear array based on the adjustable included angle as claimed in claim 2, wherein the fifth step specifically comprises:

(1) when an acoustic wave is incident from the region 1, θ_1iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_1jThe angle between the incident direction of sound wave and the normal of the inclined linear array isθ_1i+θ_1j＝π-α_n(ii) a Because the array signal on the x-axis is referenced to the array element in the most negative direction of the x-axis, and the subarray Z_hxAlso in subarray Z_hySo that when an acoustic wave is incident from region 1, the reference array element is the one that received the signal the latest, sub-array Z_hxThe array element in (1) is also larger than the subarray Z_hyThe corresponding array element in the array receives the signal late, so that the time delay parameter tau is less than 0So there is theta at this time_nxi＝-θ_1iFor the same reason have theta_nyi＝-θ_1j(ii) a In conclusion, it can be obtained that:

θ_nyi＝-θ_nxi+α_n-π (6)

θ_nyi＝θ_nxi-α_n(7)

θ_nyi＝θ_nxi-α_n

(4) when the acoustic wave is incident from the region 4, θ_4iIs the angle theta between the incident direction of the sound wave and the normal of the horizontal linear array_4jThe angle between the incident direction of the sound wave and the normal line of the inclined linear array is theta_4i-θ_4j＝α_nAccording to (1)) In the analytical method used in (1), in this case there is theta_nxi＝θ_4i，θ_nyi＝θ_4jIn conclusion, the following can be obtained:

θ_nyi＝θ_nxi-α_n

from equations (6) and (7), we can obtain:

sinθ_nyi＝sin(θ_nxi-α_n) (8)

substituting equation (8) into equation (5) then there is:

4. the underwater direction-of-arrival estimation method based on the adjustable included angle uniform linear array according to claim 3, characterized in that the sixth step specifically comprises:

5. The underwater direction-of-arrival estimation method based on the adjustable included angle uniform linear array as claimed in claim 4, wherein in step seven,i＝1,2,...K。

6. the method as claimed in claim 5, wherein the angle α between two uniform linear arrays is changed_nN1, 2,.. multidot.n, repeating steps one to seven, and α for different linear array angles_nCalculating the corresponding direction of arrival angle by formula (12), and averaging the N results to obtain the final result theta_xi,i＝1,2,...,K。

7. The underwater direction-of-arrival estimation device based on the adjustable included angle uniform linear array based on the method of claim 1 is characterized by comprising a data processing and control module, an angle control module, a transmitting module, a receiving module, an output module and a power supply module; the power module is connected with the data processing and control module, the angle control module, the transmitting module, the receiving module and the output module and can supply power to the modules;

8. The apparatus of claim 7, wherein the angle control module comprises a stepping motor and a driving circuit for controlling an angle between the two linear arrays; the stepping motor is an open-loop control motor which converts an electric pulse signal into angular displacement or linear displacement, when the driving circuit receives a pulse signal, the driving circuit drives the stepping motor to rotate for a fixed angle according to a set direction, and a desired angle value can be achieved by enabling the data processing and control module to emit a certain number of pulse signals.

9. The device of claim 7, wherein the receiving module comprises two ultrasonic receiving probe arrays, the included angle between the two arrays is variable and can be adjusted through the angle control module; the horizontal array L1 and the stepping motor are fixed together, the array L2 is installed on the stepping motor and ensures that the array L1 and the array L2 are on the same plane, and the array L2 can be driven by the stepping motor to rotate, so that the purpose of adjusting the included angle of the two arrays is achieved.

10. The apparatus of claim 9, wherein a mounting bracket is provided at the end of the array L1, the mounting bracket being made of plastic; the stepper motor stator is attached to this bracket and the stepper motor rotor is attached to the array L2.