A three-dimensional imaging method and related device for compensating for array inconsistencies

Abstract

The embodiment of the application provides a three-dimensional imaging method for compensating for inconsistency of a base array and related devices, in which the actual coordinates of each array element are considered in the solving process and the calibration model, and the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer base array under different temperatures and different amplification multiples are also considered, so that the three-dimensional imaging method for compensating for inconsistency of the base array provided by the embodiment of the application performs beam forming according to the actual array element coordinate positions, compensates for the base array element position error, considers different array element amplitude and phase errors under different temperatures and different gains, better compensates for the inconsistency of the base array, reduces the introduced amplitude and phase errors, and improves the signal-to-noise ratio of the image.

Description

Technical Field

[0001] This invention relates to the field of sonar three-dimensional imaging technology, and in particular to a three-dimensional imaging method and related apparatus for compensating for array inconsistencies. Background Technology

[0002] The receiver transducer array is the core component of 3D imaging sonar. In the existing technology, the inconsistency of the receiver transducer array is one of the main factors causing the degradation of image quality. Compensating for the inconsistency of the receiver transducer array in the beamforming algorithm of imaging sonar is an important method to improve the acoustic image quality.

[0003] 1) The degradation of image quality caused by array inconsistencies is the technical background for the need to compensate for array inconsistencies.

[0004] In the field of imaging sonar, there are two main technical indicators for evaluating image quality: the main lobe width and the side lobe height of the beam pattern. The narrower the main lobe width and the lower the side lobe height, the better the image quality.

[0005] Inconsistencies in the receiving transducer array introduce amplitude and phase errors into the system's input array signal. These errors have a relatively small impact on the main lobe width but a significant impact on the side lobe height, leading to an increase in side lobe height and consequently, increased image noise.

[0006] 2) The amplitude and phase errors introduced by the array inconsistency increase the sidelobe height.

[0007] Figure 1 This refers to the receiving array coordinate system of existing three-dimensional imaging sonar technology. For example... Figure 1 As shown, the ideal three-dimensional imaging sonar beamforming can be represented by the following formula:

[0008] The unit vector representing the wave plane of a vertical plane echo and pointing towards the sound source;

[0009] Unit vector representing beam direction

[0010] This represents the coordinates of the array element with coordinates (m,n) in the xoy plane;

[0011] wavelength This represents the weight of the array element with coordinates (m,n).

[0012] Ideally, each element of the receiving transducer array of a 3D imaging sonar lies in the xoy plane, and the spacing between adjacent elements is a constant. In this case, the beam pattern is as follows:

[0013] (1)

[0014]

[0015] Beam power is:

[0016]

[0017] When the system has array element failures and amplitude / phase errors, the beam pattern is as follows:

[0018] (2)

[0019] beam power is

[0020]

[0021]

[0022] Factors describing the failure of array elements ,in This represents the failure probability of the array element.

[0023] , Let be the amplitude error and phase error of the (m,n) array elements, respectively, which are normally distributed. They satisfy the following:

[0024]

[0025]

[0026]

[0027] From equations (1) and (2), it can be seen that when amplitude and phase errors exist:

[0028]

[0029] in:

[0030]

[0031]

[0032] Then consider the beam power:

[0033]

[0034] Then we have:

[0035]

[0036]

[0037] in

[0038]

[0039] When the weight of each array element is 1 and no array element fails, we have:

[0040]

[0041] The physical meaning of the above formula: When amplitude and phase errors exist, the average sidelobe power is increased compared to when there are no amplitude and phase errors.

[0042]

[0043] It is evident that the greater the amplitude and phase error, the larger the sidelobe amplitude and the more image noise there is. Therefore, it is necessary to compensate for the array inconsistency as much as possible during beamforming to reduce the introduced amplitude and phase error and improve the signal-to-noise ratio of the image. Summary of the Invention

[0044] This invention provides a three-dimensional imaging method and related apparatus for compensating for array inconsistencies. Beamforming is performed according to the actual array element coordinates to compensate for array element position errors. It also takes into account the amplitude and phase errors of different array elements under different temperatures and gains, thus better compensating for array inconsistencies.

[0045] In a first aspect, embodiments of the present invention provide a three-dimensional imaging method for compensating for array inconsistencies, comprising:

[0046] S1. Obtain the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array at different temperatures and different amplification factors through electrical calibration measurement;

[0047] S2. Obtain the signal transmitted by the transmitting transducer by receiving the transducer array, and measure the measurable parameters, including the coordinates of the transmitting transducer and the signal amplitude of each array element.

[0048] S3. Change the position of the transmitting transducer and repeatedly measure the measurable parameters to obtain the set of measurable parameters;

[0049] S4. Establish a system of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The fixed parameters include the operating frequency of the receiving transducer array, the first amplitude compensation coefficient, the first phase compensation coefficient, and the speed of sound. The unknown parameters include the fixed phase error, the phase error caused by the impedance difference of the i-th array element, the center coordinates of the receiving transducer array, and the actual coordinates of the i-th array element. Solve the system of equations to obtain the actual coordinates of each array element, the second amplitude compensation coefficient, and the second phase compensation coefficient.

[0050] S5. Establish a beamforming calibration model based on the actual coordinates, amplitude compensation coefficient, and phase compensation coefficient of the i-th array element;

[0051] S6. Perform sonar three-dimensional imaging based on the beamforming calibration model.

[0052] In conjunction with the first aspect, in one implementation of an embodiment of this application, step S5 specifically includes:

[0053] The beamforming calibration model is constructed as follows:

[0054]

[0055] in, The second amplitude compensation coefficient for the i-th array element. The demodulated data output by the i-th array element. The second phase compensation coefficient for the i-th array element. To receive the operating frequency of the transducer array, The distance between the target and the origin of the coordinate system. Let be the coordinates of the i-th array element. The current beam direction is given by C, the speed of sound is given by m, the column number of the i-th element is given by n, the row number of the i-th element is given by N, and the number of elements per row and per column in the array of the area array receiver transducer is given by N.

[0056] In conjunction with the first aspect, in one implementation of the embodiments of this application, step S4 includes:

[0057] S401. Establish the first set of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The first set of equations includes:

[0058]

[0059] in, For fixed phase error; The phase error is caused by the impedance difference of the i-th array element. For operating frequency, This represents the distance between the transmitting transducer and the i-th array element. This indicates the center coordinates of the receiving transducer array. Let i be the actual coordinates of the i-th array element. The coordinates of the transmitting transducer are... The amplitude error is introduced by the difference in the sensitivity of the array elements. Let be the signal amplitude of the i-th array element. The signal amplitude of the first array element;

[0060] S402. Repeat steps S3 and S401 several times to obtain multiple sets of first equations;

[0061] S403. Solve the system of multiple first equations simultaneously to obtain the actual coordinates of the i-th element. The phase error caused by the impedance difference of the i-th array element Amplitude error compensation coefficient Among them, amplitude error compensation coefficient Amplitude error introduced by differences in array element sensitivity The average value.

[0062] S404. Determine the actual coordinates, second amplitude compensation coefficient, and second phase compensation coefficient of each array element based on the first amplitude compensation coefficient, the first phase compensation coefficient, and the parameters obtained in step S403.

[0063] In conjunction with the first aspect, in one implementation of the embodiments of this application, step S404 includes:

[0064] The actual coordinates, amplitude compensation coefficient, and phase compensation coefficient of each array element are determined based on the second set of equations. The second set of equations includes:

[0065]

[0066] in, This is the second amplitude compensation coefficient. This is the amplitude error compensation coefficient. This is the first amplitude compensation coefficient. This is the second phase compensation coefficient. The first phase compensation coefficient, The phase error is caused by the impedance difference of the i-th array element. Let be the coordinates of the i-th array element.

[0067] In conjunction with the first aspect, in one implementation of the embodiments of this application, step S2 includes the following:

[0068] The receiving transducer array and the transmitting transducer are mounted on the slide rails of the anechoic water tank.

[0069] Step S2 specifically includes:

[0070] The first coordinate of the transmitting transducer is obtained by measuring the scale on the silencing water tank, the second coordinate of the transmitting transducer is obtained by measuring the scale on the trolley rail, and the third coordinate of the transmitting transducer is obtained by measuring the scale on the trolley lifting device.

[0071] In conjunction with the first aspect, in one implementation of the embodiments of this application, step S1 specifically includes:

[0072] S101. Place the receiving transducer array into a high and low temperature chamber, set the initial temperature T, and set the initial amplification factor G of the receiving transducer array through the host computer. Then record the amplitude and phase of the demodulated output signal of the receiving transducer array.

[0073] S102. Change the temperature T and the amplification factor G, and then record the amplitude and phase of the demodulated output signal of the receiving transducer array, so as to obtain the amplitude and phase of the output signal of the receiving transducer array at different temperatures and amplification factors.

[0074] S103. Determine the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array based on the amplitude and phase of the output signal of the receiving transducer array at different temperatures and amplification factors.

[0075] In conjunction with the first aspect, in one implementation of the embodiments of this application, step S103 specifically includes:

[0076] The first amplitude compensation coefficient is determined using the formula for the first amplitude compensation coefficient. The formula for the first amplitude compensation coefficient is as follows:

[0077] ;

[0078] in, This is the first amplitude compensation coefficient. Let G be the amplitude of the i-th element at temperature G and amplification factor T.

[0079] The first phase compensation coefficient is determined using the formula for the first phase compensation coefficient. The formula for the first phase compensation coefficient is as follows:

[0080] ;

[0081] in, The first phase compensation coefficient, Let be the phase of the i-th array element at temperature G and amplification factor T.

[0082] Secondly, embodiments of this application provide a three-dimensional imaging device for compensating for array inconsistencies, comprising:

[0083] The electrical calibration module is used to obtain the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array at different temperatures and different amplification factors through electrical calibration measurements.

[0084] The processing module is used to acquire the signal transmitted by the transmitting transducer through the receiving transducer array and measure measurable parameters, including the coordinates of the transmitting transducer and the signal amplitude of each array element.

[0085] The processing module is also used to change the position of the transmitting transducer, repeatedly measure the measurable parameters, and obtain a set of measurable parameters;

[0086] The processing module is also used to establish a set of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The fixed parameters include the operating frequency, compensation coefficient, and speed of sound of the receiving transducer array. The unknown parameters include the fixed phase error, the phase error caused by the impedance difference of the i-th array element, the center coordinates of the receiving transducer array, and the actual coordinates of the i-th array element. Solving the set of equations yields the actual coordinates of each array element, the second amplitude compensation coefficient, and the second phase compensation coefficient.

[0087] The processing module is also used to establish a beamforming calibration model based on the actual coordinates, amplitude compensation coefficient, and phase compensation coefficient of the i-th array element;

[0088] The imaging module is used for sonar three-dimensional imaging based on the beamforming calibration model.

[0089] Thirdly, embodiments of this application provide a data processing device, which includes one or more processors, a memory, and a communication interface;

[0090] The memory contains program code;

[0091] The processor implements the method described in the first aspect when executing program code in memory.

[0092] Fourthly, embodiments of this application provide a computer-readable storage medium that, when instructions are executed on a computer device, causes the computer device to perform the method as described in the first aspect.

[0093] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages:

[0094] This application provides a three-dimensional imaging method and related apparatus for compensating for array inconsistencies. The solution process and calibration model both consider the actual coordinates of each array element, and also take into account the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array under different temperatures and amplification factors. Therefore, the three-dimensional imaging method for compensating for array inconsistencies provided in this application performs beamforming according to the actual array element coordinate positions, compensating for array element position errors. It also considers the amplitude and phase errors of different array elements under different temperatures and gains, better compensating for array inconsistencies, thereby reducing the introduced amplitude and phase errors and improving the signal-to-noise ratio of the image. Attached Figure Description

[0095] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0096] Figure 1 The receiving array coordinate system is provided in the existing three-dimensional imaging sonar technology;

[0097] Figure 2 A top view of the anechoic water tank provided in an embodiment of this application;

[0098] Figure 3 A schematic diagram of a three-dimensional imaging method for compensating for array inconsistencies provided in an embodiment of this application;

[0099] Figure 4 A perspective view of the anechoic water tank provided in the embodiments of this application;

[0100] Figure 5 A schematic diagram of the internal modules of a three-dimensional imaging device for compensating for array inconsistencies provided in this application embodiment;

[0101] Figure 6 A schematic diagram of a data processing device provided in an embodiment of this application. Detailed Implementation

[0102] This invention provides a three-dimensional imaging method and related apparatus for compensating for array inconsistencies. Beamforming is performed according to the actual array element coordinates to compensate for array element position errors. It also takes into account the amplitude and phase errors of different array elements under different temperatures and gains, thus better compensating for array inconsistencies.

[0103] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0104] When the applicant was researching how to compensate for array inconsistencies as much as possible during beamforming, thereby reducing the introduced amplitude and phase errors and improving the signal-to-noise ratio of the image, the applicant first studied how to obtain compensation coefficients through acoustic calibration. Before using the traditional uniform FFT beamforming algorithm, the input of each array element was multiplied by the corresponding compensation coefficient to compensate for inconsistencies.

[0105] 1) Basic principles of commonly used methods:

[0106] Acoustic calibration is used to obtain the amplitude and phase differences between the actual and theoretical output signals of the receiving array elements. Before beamforming, amplitude and phase compensation is performed on the output signal of each receiving array element to make it closer to the ideal output signal. This is currently the most commonly used method to compensate for array inconsistencies.

[0107] Assume the sound signal s(t) is at an angle If the signal is incident on a receiving array and the number of array elements is N, then the signal output by the i-th element when there is no amplitude or phase error is:

[0108]

[0109] Then define:

[0110]

[0111]

[0112] When amplitude and phase errors exist, taking the first array element as a reference, the amplitude and phase errors can be expressed as:

[0113]

[0114] When amplitude and phase errors exist, the output of each element in the receiving array is:

[0115]

[0116] During the acoustic calibration process Since the signal emitted by the sound source can be obtained through measurement and is a known quantity, the maximum likelihood estimation covariance matrix is ​​obtained by repeatedly measuring the signal emitted by the sound source using a receiving transducer, and then eigenvalue decomposition is performed.

[0117]

[0118] Where q1 is the eigenvector corresponding to the largest eigenvalue, the following relationship exists:

[0119]

[0120] because Since it is known, matrix D can be solved directly.

[0121] 2) Calibration steps:

[0122] Step 1: Set up the experimental environment in the anechoic water tank, such as... Figure 2 As shown, Figure 2This is a top view of the anechoic pool provided in an embodiment of this application. The specific construction method is as follows: a three-dimensional imaging sonar is placed in the water, with the receiving array normal parallel to the horizontal plane and parallel to the length direction of the pool;

[0123] The sonar is located on the centerline of the pool, with its depth direction at the middle depth of the pool;

[0124] When a point sound source is placed in water, the distance between the sound source and the sonar satisfies the far-field condition (greater than D2 / λ, where D is the diagonal length of the receiving array).

[0125] The sound source is within the sonar's field of view.

[0126] Step 2: Use the anechoic pool's hovercraft and scale to measure the relative position between the sound source and the center of the receiving array, and obtain the accurate distance, horizontal angle, and elevation angle of the sound source relative to the sonar.

[0127] Step 3: The point sound source emits sound pulses, the sonar starts working to receive signals, and the acquisition matrix X(n) is collected;

[0128] Step 4: Solve for matrix D.

[0129] 3) Three-dimensional imaging algorithm based on commonly used compensation array inconsistency method.

[0130] The commonly used formulas for 3D imaging algorithms that compensate for array inconsistencies are as follows:

[0131]

[0132] K represents the sequence number of the demodulated data output for each phase, ( ) indicates the beam direction. For array element weights, This is the Kth demodulated data output by the (m,n)th array element. The amplitude and phase error measurement of the (m,n)th element relative to the lower (1,1)th element (the corresponding element in matrix D solved during acoustic calibration, which is a complex number). For the sonar operating frequency,

[0133]

[0134] For the transmit pulse width, Let be the position vector of the (m,n)th element. The position vector uses the design value, where d is the center-to-center distance between adjacent elements, n represents the row number of the element, m represents the column number, and C is the speed of sound in water. The unit direction vector of the target's orientation

[0135] As can be seen from the above three-dimensional imaging algorithm formula, regardless of the value of K or the direction in which the target is pointing, the compensation coefficient for the (m,n)th element is the same.

[0136] Therefore, the applicant found that the typical characteristics of the above-mentioned three-dimensional imaging algorithm mainly include two aspects:

[0137] A. The compensation coefficient for each array element is a constant;

[0138] B. The positions of the array elements are determined using the design values.

[0139] Regarding these two characteristics, the applicant found:

[0140] 1. The compensation coefficient for each array element is constant. However, when the gain of the analog circuit is different, the distribution of phase error and amplitude error is different, and the compensation coefficient is variable. Using a constant as the compensation coefficient will still result in a large amplitude and phase error after compensation.

[0141] 2. During the manufacturing process of the transducer array, there are processing errors and placement errors. After long-term use, the foam and other components will creep, and the coordinates of each array element will deviate from the design value. The phase error distribution caused by these deviations varies with the echo direction. Therefore, if the design value is used as the array element position, the calibration of the transducer using the echo in one direction cannot guarantee that the amplitude and phase errors of the echoes in other directions will be corrected. On the contrary, it may increase the amplitude and phase errors.

[0142] Therefore, the applicant made improvements and proposed a three-dimensional imaging method to compensate for array inconsistencies. Please refer to [link / reference]. Figure 3 , Figure 3 This is a schematic diagram of a three-dimensional imaging method for compensating for array inconsistencies provided in an embodiment of this application. The imaging method includes:

[0143] S1. Obtain the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array at different temperatures and different amplification factors through electrical calibration measurement;

[0144] In this embodiment, since different temperatures and magnifications affect imaging, the first aspect of this embodiment determines the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array (which includes multiple array elements, with one array element corresponding to one analog channel, and therefore can also be referred to as including multiple analog channels) under different temperatures and magnifications. The differences between the array elements in the receiving transducer array under different temperatures and magnifications can be tested in various ways to determine the corresponding first amplitude compensation coefficient and first phase compensation coefficient. This embodiment provides the following specific steps:

[0145] S101. Place the receiving transducer array into a high and low temperature chamber, set the initial temperature T, and set the initial amplification factor G of the receiving transducer array through the host computer. Then record the amplitude and phase of the demodulated output signal of the receiving transducer array.

[0146] Understandably, a high and low temperature chamber is a chamber with adjustable temperature. Generally, the initial temperature can be set to -2 degrees Celsius, and the initial magnification can be set to 1.

[0147] S102. Change the temperature T and the amplification factor G, and then record the amplitude and phase of the demodulated output signal of the receiving transducer array, so as to obtain the amplitude and phase of the output signal of the receiving transducer array at different temperatures and amplification factors.

[0148] At this point, the amplitude and phase of the output signals of all analog channels (all array elements) at different gains and temperatures were measured.

[0149] S103. Determine the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array based on the amplitude and phase of the output signal of the receiving transducer array at different temperatures and amplification factors.

[0150] Specifically, the first amplitude compensation coefficient can be determined using the formula for the first amplitude compensation coefficient, which is as follows:

[0151] ;

[0152] in, This is the first amplitude compensation coefficient. The amplitude of the i-th element at temperature G and amplification factor T (measured in steps S101 and S102 above). The amplitude of the first array element at temperature G and amplification factor T is taken as the reference.

[0153] The first phase compensation coefficient is determined using the formula for the first phase compensation coefficient. The formula for the first phase compensation coefficient is as follows:

[0154] ;

[0155] in, The first phase compensation coefficient, The phase of the i-th element at temperature G and amplification factor T is measured in steps S101 and S102 above. The phase of the first array element at temperature G and amplification factor T is taken as the reference.

[0156] At this point, the first amplitude compensation coefficient and the first phase compensation coefficient of all array elements in the receiving transducer array under different temperatures and different amplification factors can be determined.

[0157] It is understood that the different temperatures and different magnifications mentioned above refer to the temperatures and magnifications set in steps S101 and S102. In different specific application scenarios, various temperatures and magnifications may need to be set, and this application embodiment does not limit this.

[0158] S2. Obtain the signal transmitted by the transmitting transducer by receiving the transducer array, and measure the measurable parameters, including the coordinates of the transmitting transducer and the signal amplitude of each array element.

[0159] In this embodiment, the transmitting transducer can be controlled to transmit signals, typically acoustic signals, to the receiving transducer array. The coordinates of the transmitting transducer can be measured in various ways; this embodiment provides one such method as follows:

[0160] Figure 4 This is a perspective view of an anechoic water tank provided in an embodiment of this application. Figure 4 As shown, the receiving transducer array and the transmitting transducer can be mounted on the slide rails of the anechoic water tank. The third coordinate (depth coordinate z) of the transmitting transducer can then be obtained through the scale on the crane elevator. t0 Furthermore, the scale reading of the anechoic pool is the first coordinate of the transmitting transducer (x-axis). t0 The scale reading on the trolley track is the second coordinate of the transmitting transducer (vertical coordinate y). t0 Therefore, the first coordinate of the transmitting transducer can be obtained by the scale on the silencing water tank, the second coordinate of the transmitting transducer can be obtained by the scale on the trolley rail, and the third coordinate of the transmitting transducer can be obtained by the scale on the trolley lifting device.

[0161] In specific application scenarios, readings can be taken manually and input into a computer to import the algorithm model, or automatic readings can be taken using a device similar to an electronic vernier caliper. This application does not limit the specific method used.

[0162] On the other hand, the signal amplitude of each array element can be detected by a detector, which is a conventional technique and will not be elaborated here.

[0163] S3. Change the position of the transmitting transducer and repeatedly measure the measurable parameters to obtain the set of measurable parameters;

[0164] In the embodiments of this application, after measuring a measurable parameter once, the position of the transmitting transducer can be changed, and the measurable parameter can be measured repeatedly to obtain a sufficient number of measurable parameters, thereby establishing a sufficient set of equations based on the sufficient number of measurable parameters.

[0165] In the embodiments of this application, the measurement is generally repeated 5 times, and the specific principle will be explained later.

[0166] S4. Establish a system of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The fixed parameters include the operating frequency of the receiving transducer array, the first amplitude compensation coefficient, the first phase compensation coefficient, and the speed of sound. The unknown parameters include the fixed phase error, the phase error caused by the impedance difference of the i-th array element, the center coordinates of the receiving transducer array, and the actual coordinates of the i-th array element. Solve the system of equations to obtain the actual coordinates of each array element, the second amplitude compensation coefficient, and the second phase compensation coefficient.

[0167] In this embodiment, a set of equations is established based on the set of measurable parameters, fixed parameters, and unknown parameters. Then, the equations are solved to obtain the actual coordinates, second amplitude compensation coefficient, and second phase compensation coefficient of each array element. This solution process considers both the actual coordinates of each array element and the first amplitude compensation coefficient and first phase compensation coefficient of the receiving transducer array under different temperatures and different amplification factors. Therefore, this method performs beamforming according to the actual array element coordinates, compensating for the array element position error, and also considers the amplitude and phase errors of different array elements under different temperatures and different gains, thus better compensating for the inconsistency of the array.

[0168] Specifically, the process of establishing the system of equations is as follows:

[0169] S401. Establish the first set of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The first set of equations includes:

[0170]

[0171] in, For fixed phase error; The phase error is caused by the impedance difference of the i-th array element. For operating frequency, This represents the distance between the transmitting transducer and the i-th array element. This indicates the center coordinates of the receiving transducer array. Let i be the actual coordinates of the i-th array element. The coordinates of the transmitting transducer are... The amplitude error is introduced by the difference in the sensitivity of the array elements. Let be the signal amplitude of the i-th array element. The signal amplitude of the first array element;

[0172] The coordinates of the transmitting transducer in the embodiments of this application and the signal amplitude of the i-th array element It can be measured through steps S2 and S3, and is a measurable parameter.

[0173] In the embodiments of this application, the operating frequency The speed of sound C is a fixed parameter.

[0174] In the embodiments of this application, the phase error is fixed. Receiver transducer array center coordinates The actual coordinates of the i-th array element Phase error caused by impedance difference of the i-th array element The parameter is unknown.

[0175] In the embodiments of this application, the phase error compensation coefficient Array element position vector Transmitter position vector Amplitude error introduced by differences in array element sensitivity All of these can be directly determined or expressed algebraically through measurable parameters, fixed parameters, and unknown parameters.

[0176] S402. Repeat steps S3 and S401 several times to obtain multiple sets of first equations;

[0177] In this embodiment, a first system of equations can be established for each array element, including the aforementioned unknown parameters. Wherein, the actual coordinates of the i-th array element... Phase error caused by impedance difference of the i-th array element All are unknown parameters related to the i-th array element (i.e. and These four parameters). When establishing the first set of equations for K array elements, we can determine K sets of first equations, including 4K unknown parameters related to the i-th array element, and another 4 unknown parameters unrelated to the i-th array element, i.e., fixed phase error. Receiver transducer array center coordinates It can also be called... , , and These four parameters.

[0178] Each time the transmitting transducer is changed, only a fixed phase error is added to the 4K+4 unknown parameters mentioned above. The variables are such that after four more measurements, a system of 5K equations will be established, with a total of 4K+8 unknowns, which meets the conditions for establishing overdetermined equations.

[0179] Therefore, in general, this application repeats steps S3 and S401 5 times to obtain 5K sets of first equations.

[0180] S403. Solve the system of multiple first equations simultaneously to obtain the actual coordinates of the i-th element. The phase error caused by the impedance difference of the i-th array element Amplitude error compensation coefficient Among them, amplitude error compensation coefficient Amplitude error introduced by differences in array element sensitivity The average value.

[0181] In this embodiment, according to the solution of the overdetermined equations, the 4K+8 unknown parameters can be solved using the least squares method, thereby obtaining the actual coordinates of the i-th array element. The phase error caused by the impedance difference of the i-th array element Amplitude error compensation coefficient Among them, amplitude error compensation coefficient Amplitude error introduced by differences in array element sensitivity The average value.

[0182] S404. Determine the actual coordinates, second amplitude compensation coefficient, and second phase compensation coefficient of each array element based on the first amplitude compensation coefficient, the first phase compensation coefficient, and the parameters obtained in step S403.

[0183] In this embodiment of the application, the first amplitude compensation coefficient can be obtained by combining step S1 and the amplitude error compensation coefficient obtained by step S403. Determine the final second amplitude compensation coefficient. Alternatively, the first phase compensation coefficient obtained in step S1 and the phase error obtained in step S403 can be combined. The final second phase compensation coefficient is determined. Specifically, the actual coordinates, second amplitude compensation coefficient, and second phase compensation coefficient of each array element can be determined using the second set of equations. The second set of equations includes:

[0184]

[0185] in, This is the second amplitude compensation coefficient. This is the amplitude error compensation coefficient. This is the first amplitude compensation coefficient. This is the second phase compensation coefficient. The first phase compensation coefficient, The phase error is caused by the impedance difference of the i-th array element. Let be the coordinates of the i-th array element.

[0186] S5. Establish a beamforming calibration model based on the actual coordinates, amplitude compensation coefficient, and phase compensation coefficient of the i-th array element;

[0187] In this embodiment, the applicant achieves three-dimensional imaging that compensates for array inconsistencies using a beamforming calibration model developed independently. The equation for this beamforming calibration model is:

[0188]

[0189] in, The second amplitude compensation coefficient for the i-th array element. The demodulated data output by the i-th array element. The second phase compensation coefficient for the i-th array element. To receive the operating frequency of the transducer array, The distance between the target and the origin of the coordinate system. Let i be the actual coordinates of the i-th array element. The current beam direction is given by C, the speed of sound is given by m, the column number of the i-th element is given by n, the row number of the i-th element is given by N, and the number of elements in each row and column of the receiver transducer array is given by N.

[0190] In the embodiments of this application, a beamforming calibration model is constructed by using an improved second amplitude compensation coefficient, a second phase compensation coefficient, and the actual coordinates of the array elements. This model enables beamforming according to the actual coordinate positions of the array elements, compensating for the positional errors of the array elements. It also takes into account the amplitude and phase errors of different array elements under different temperatures and gains, thus better compensating for the inconsistencies of the array.

[0191] S6. Perform sonar three-dimensional imaging based on the beamforming calibration model.

[0192] In the embodiments of this application, beamforming algorithms can be used to perform sonar three-dimensional imaging based on the equations of the beamforming calibration model. This is a conventional technique for those skilled in the art and will not be elaborated here.

[0193] To more deeply explain the technical solution of this application, specific implementation examples are provided in the embodiments of this application as follows:

[0194] I. Establishing a calibration model

[0195] Assuming that the number of array elements in each row and each column of the receiving transducer array is N, the following calibration model is established:

[0196] 1. The theoretical coordinates of each array element are: The actual coordinates are , where m is the column number of the i-th element and n is the row number of the i-th element. The element position vector is:

[0197] 2. The amplitude compensation coefficient for the analog channel output signal of each array element is: Phase compensation is Where G is the current gain of the simulation channel of the array element, and T is the current temperature.

[0198] The beamforming scheme is as follows:

[0199]

[0200] in The demodulated data output by the i-th array element. The distance between the target and the origin of the coordinate system. The current beam direction is represented by C, and the speed of sound is represented by C.

[0201] The above model performs beamforming according to the actual array element coordinates, compensating for the array element position error, and also considers the amplitude and phase errors of the analog channel under different temperatures and gains, thus better compensating for the inconsistencies between the array and the analog channel.

[0202] II. Calibration Method:

[0203] Step 1: Electrical calibration measurement ,

[0204] Place the sonar receiver's analog channel into a high-low temperature chamber and set the temperature. Degree. The amplification factor of the analog channel is set to [value] via the host computer. .

[0205] Record the amplitude and phase of the demodulated output signals for all channels: .

[0206] Configure via host computer Repeat step 2) until until.

[0207] Adjusting the temperature of the high-temperature chamber Repeat steps 2) to 3) until... until.

[0208] At this point, the amplitude and phase of the output signals of all analog channels at different gains and temperatures were measured;

[0209] Using the first channel as a reference, the amplitude compensation coefficient for the i-th channel is: ; ;

[0210] The compensation coefficients of the analog channel were then obtained through electrical calibration. .

[0211] Step 2: Acoustic calibration to obtain the positions of array elements;

[0212] 1. Establish a calibration environment in the anechoic water tank;

[0213] a. such as Figure 4 As shown, a transmitting transducer is mounted on the left-hand tractor in the anechoic water tank to simulate a point target;

[0214] b. Use the right-hand tractor to mount sonar equipment for receiving signals;

[0215] 2. Measure the position of the launch array;

[0216] a. Take a corner of the pool as the origin;

[0217] b. Measure the coordinates of the transmitting transducer using the scales on the anechoic water tank, the trolley rails, and the trolley elevator.

[0218] 3. Transmit sound waves, obtain the demodulated output of each channel, and compensate for the amplitude and phase errors of the analog channels:

[0219]

[0220] For each analog channel, the following equation can be established:

[0221]

[0222] in, The phase error is a fixed constant. The phase error caused by the impedance difference of the array elements is an inherent property of the array elements. For operating frequency, This represents the distance between the transmitting transducer and the i-th element. The coordinates of the center of the receiving array within the anechoic pool are constants. The amplitude error is caused by the difference in the sensitivity of the array elements. Based on the plane wave assumption, theoretically, the signal amplitudes output by all array elements should be equal.

[0223] As can be seen from the above, for this measurement, assuming there are K array elements, then we have , , , There are a total of 4K+4 variables. Equation (4) establishes a system of K equations, and each time the transmitting transducer is changed for measurement, only the following equations are added. One variable;

[0224] Therefore, after four more measurements, a system of 5K equations will be established, with a total of 4K+8 unknowns, which meets the conditions for establishing overdetermined equations.

[0225] 4. Change the position of the transmitting transducer four times, repeat steps 2 and 3, establish a system of 5K equations, and solve for 4K+8 unknowns using the least squares method.

[0226] 5. Due to the four measurements The solutions are different, therefore the final choice is... Amplitude error caused by the sensitivity error of the array elements obtained from five measurements The arithmetic mean.

[0227] After acoustic calibration, the actual position coordinates of each array element can be obtained. The amplitude error compensation coefficient caused by sensitivity can be obtained for each array element. Phase error caused by inconsistency in array element impedance .

[0228] Then, the coordinates, amplitude compensation coefficient, and phase compensation coefficient of each array element are:

[0229]

[0230] Substituting equation (5) into equation (3) yields the final three-dimensional imaging algorithm that compensates for array inconsistencies and the inconsistencies of analog channels under different gains and temperatures.

[0231] Figure 5 A schematic diagram of the internal modules of a three-dimensional imaging device for compensating for array inconsistencies provided in this application embodiment. The internal modules of the three-dimensional imaging device 500 for compensating for array inconsistencies include:

[0232] Electrical calibration module 501 is used to perform or implement the aforementioned Figure 3 Step S1 in the corresponding embodiments;

[0233] Processing module 502 is used to perform or implement the aforementioned Figure 3 Steps S2, S3, S4, and S5 in the corresponding embodiments;

[0234] Imaging module 503 is used to perform or implement the aforementioned Figure 3 Step S6 in the corresponding embodiments.

[0235] Figure 6 This is a schematic diagram of a data processing device provided in an embodiment of this application. The data processing device 600 includes a memory 602, a processor 601, and a computer program 603 stored in the memory 602 and executable on the processor 601. When the processor 601 executes the computer program 603, it implements... Figure 3 The methods of the corresponding embodiments.

[0236] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps described in the various method embodiments above.

[0237] This application provides a computer program product that, when run on a mobile terminal, enables the mobile terminal to implement the steps described in the above-described method embodiments.

[0238] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0239] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0240] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0241] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0242] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0243] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-dimensional imaging method for compensating for array inconsistencies, characterized in that, include: Step S1: Obtain the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array at different temperatures and different amplification factors through electrical calibration measurement; Step S2: Obtain the signal transmitted by the transmitting transducer through the receiving transducer array, and measure the measurable parameters, including the coordinates of the transmitting transducer and the signal amplitude of each element in the receiving transducer array; Step S3: Change the position of the transmitting transducer and repeatedly measure the measurable parameters to obtain a set of measurable parameters; Step S4: Establish a system of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The fixed parameters include the operating frequency of the receiving transducer array, the first amplitude compensation coefficient, the first phase compensation coefficient, and the speed of sound. The unknown parameters include the fixed phase error, the phase error caused by the impedance difference of the i-th array element, the center coordinates of the receiving transducer array, and the actual coordinates of the i-th array element. Solve the system of equations to obtain the actual coordinates of each array element, the second amplitude compensation coefficient, and the second phase compensation coefficient. Step S5: Establish a beamforming calibration model based on the actual coordinates of the i-th array element, the amplitude compensation coefficient, and the phase compensation coefficient; Step S6: Perform sonar three-dimensional imaging based on the beamforming calibration model.

2. The three-dimensional imaging method according to claim 1, characterized in that, Step S5 specifically includes: The beamforming calibration model is constructed as follows: ， in, The second amplitude compensation coefficient for the i-th array element. The demodulated data output by the i-th array element. The second phase compensation coefficient for the i-th array element. The operating frequency of the receiving transducer array is [the frequency of the array]. The distance between the target and the origin of the coordinate system. Let the coordinates be those of the i-th array element. Where C is the current beam direction, m is the column number of the i-th array element, n is the row number of the i-th array element, N is the number of array elements in each row and column of the receiving transducer array, G is the temperature, and T is the amplification factor.

3. The three-dimensional imaging method according to claim 1, characterized in that, Step S4 includes: Step S401: Establish a first set of equations based on the measurable parameter set, the fixed parameters, and the unknown parameters. The first set of equations includes: ， in, The fixed phase error; The phase error is caused by the impedance difference of the i-th array element. The operating frequency, This represents the distance between the transmitting transducer and the i-th array element. This indicates the center coordinates of the receiving transducer array. The actual coordinates of the i-th array element are... The coordinates of the transmitting transducer are given. The amplitude error is introduced by the difference in the sensitivity of the array elements. The signal amplitude of the i-th array element. The signal amplitude of the first array element is given by C, where C is the speed of sound. Step S402, repeat steps S3 and S401 several times to obtain multiple sets of the first equations; Step S403: Solve the first system of equations simultaneously to obtain the actual coordinates of the i-th array element. The phase error caused by the impedance difference of the i-th array element Amplitude error compensation coefficient Among them, amplitude error compensation coefficient Amplitude error introduced by the difference in sensitivity of the array elements The average value; Step S404: Determine the actual coordinates, the second amplitude compensation coefficient, and the second phase compensation coefficient of each array element based on the first amplitude compensation coefficient, the first phase compensation coefficient, and the parameters obtained in step S403.

4. The three-dimensional imaging method according to claim 3, characterized in that, Step S404 includes: The actual coordinates, amplitude compensation coefficient, and phase compensation coefficient of each array element are determined according to the second set of equations, which includes: ， in, This is the second amplitude compensation coefficient. The amplitude error compensation coefficient is... This is the first amplitude compensation coefficient. This is the second phase compensation coefficient. This is the first phase compensation coefficient. The phase error is caused by the impedance difference of the i-th array element. Let G be the coordinate of the i-th array element, G be the temperature, and T be the magnification factor.

5. The three-dimensional imaging method according to any one of claims 1 to 4, characterized in that, Before step S2, the following are included: The receiving transducer array and the transmitting transducer are mounted on the slide rails of the silencing water tank; Step S2 specifically includes: The first coordinate of the transmitting transducer is obtained by measuring the scale on the silencing water tank, the second coordinate of the transmitting transducer is obtained by measuring the scale on the trolley rail, and the third coordinate of the transmitting transducer is obtained by measuring the scale on the trolley lifting device.

6. The three-dimensional imaging method according to any one of claims 1 to 4, characterized in that, Step S1 specifically includes: Step S101: Place the receiving transducer array into a high and low temperature chamber, set the initial temperature T, and set the initial amplification factor G of the receiving transducer array through the host computer. Then record the amplitude and phase of the demodulated output signal of the receiving transducer array. Step S102: Change the temperature T and the amplification factor G, and then record the amplitude and phase of the demodulated output signal of the receiving transducer array, thereby obtaining the amplitude and phase of the output signal of the receiving transducer array at different temperatures and amplification factors; Step S103: Determine the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array based on the output signal amplitude and phase of the receiving transducer array at different temperatures and amplification factors.

7. The three-dimensional imaging method according to claim 6, characterized in that, Step S103 specifically includes: The first amplitude compensation coefficient is determined by the formula for the first amplitude compensation coefficient, which is: ； in, This is the first amplitude compensation coefficient. Let G be the amplitude of the i-th element at temperature G and amplification factor T. The first phase compensation coefficient is determined using the formula for the first phase compensation coefficient, which is: ； in, The first phase compensation coefficient, Let be the phase of the i-th array element at temperature G and amplification factor T.

8. A three-dimensional imaging device for compensating for array inconsistencies, characterized in that, include: The electrical calibration module is used to obtain the first amplitude compensation coefficient and the first phase compensation coefficient of the receiving transducer array at different temperatures and different amplification factors through electrical calibration measurements. The processing module is used to acquire the signal transmitted by the transmitting transducer through the receiving transducer array and measure measurable parameters, including the coordinates of the transmitting transducer and the signal amplitude of each element in the receiving transducer array. The processing module is also used to change the position of the transmitting transducer, repeatedly measure the measurable parameters, and obtain a set of measurable parameters; The processing module is also used to establish a system of equations based on the set of measurable parameters, fixed parameters, and unknown parameters. The fixed parameters include the operating frequency of the receiving transducer array, the compensation coefficient, and the speed of sound. The unknown parameters include the fixed phase error, the phase error caused by the impedance difference of the i-th array element, the center coordinates of the receiving transducer array, and the actual coordinates of the i-th array element. Solving the system of equations yields the actual coordinates of each array element, the second amplitude compensation coefficient, and the second phase compensation coefficient. The processing module is also used to establish a beamforming calibration model based on the actual coordinates of the i-th array element, the amplitude compensation coefficient, and the phase compensation coefficient; An imaging module is used to perform sonar three-dimensional imaging based on the beamforming calibration model.

9. A data processing device, characterized in that, The data processing device includes one or more processors, a memory, and a communication interface; The memory stores program code; When the processor executes the program code in the memory, it implements the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, When the instructions are executed on a computer device, the computer device causes the computer device to perform the method as described in any one of claims 1 to 7.

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