Far and near field wallboard leakage source full-field positioning method based on linear acoustic array

Abstract

The invention provides a far and near field wallboard leakage source full-field positioning method based on a linear acoustic array, belongs to the field of high-precision positioning, and solves the problems that a wallboard structure leakage source positioning scheme needs more sensor arrays and is inconvenient to use actually, and the calculation amount required for ensuring the precision of a positioning algorithm is large and is not beneficial to real-time monitoring. Comprising the following steps: step 1, determining a frequency dispersion curve according to a structure and a material of a detected wallboard, extracting a signal main frequency, and determining an angle threshold value according to an array structure and two selected sub-arrays; 2, calculating a positioning result difference value of the two sub-arrays, and comparing the positioning result difference value with a threshold value; 3, if the positioning result difference value is not larger than the threshold value, far-field positioning is carried out, far-field positioning is completed through the full array, and a far-field positioning result is output; 4, if the positioning result difference value is smaller than the threshold value, near-field positioning is carried out, and an improved 2Dmuic algorithm is adopted to process the full-array signals to obtain a near-field positioning result.

Description

Technical Field

[0001] The invention relates to a full-field positioning method for far-field and near-field wallboard leakage sources based on a linear acoustic array, and belongs to the field of high-precision positioning. Background Art

[0002] In recent years, aerospace technology has advanced rapidly, and the service life of large spacecraft such as manned spacecraft and space stations has been continuously extended. At the same time, the number of space debris in low-Earth orbit is also growing rapidly, increasing the risk of collision and leakage of spacecraft in orbit. Damage and leakage of the outer structure of the spacecraft will seriously undermine the stability of the internal environment of the spacecraft, threaten the personal safety of astronauts, and cause great harm to the operation of large equipment such as space stations. Timely and effective positioning and detection of the leakage source is conducive to rapid repair of the leakage area and ensuring the safety of spacecraft and astronauts.

[0003] Therefore, people have studied the problem of locating the leakage source of the wall panel structure. Qi Lei et al. proposed in their paper to use the beamforming energy focusing method to achieve positioning. This method uses a far-field narrowband model, delays and superimposes the signals of each channel at different angles, and searches for the spectral peak of the superimposed image to obtain the azimuth of the leakage source.

[0004] In the technical solution of Qi Lei et al., the positioning accuracy of the impact is affected by the position of the leakage source. When the distance between the leakage source and the sensor array is close, the far-field condition is not met, and the positioning error is large. Xin Fengxian et al. disclosed in the invention patent CN113405736A "a method and system for positioning the leakage source based on the acoustic emission characteristics of gas leakage in a plate-like structure". This method uses a cross-shaped sensor array, pre-processes the signal, and uses the surround sensor music algorithm for orientation. Then, a large number of intersections are obtained through the orientation results of multiple groups of ring sensors, and the K-means clustering algorithm is used to process the obtained intersections to achieve high-precision positioning. In the technical solution of Xin Fengxian et al., the influence of dispersion phenomenon in the positioning of the leakage source is better solved, and high-precision positioning can be achieved. However, this solution requires more sensor arrays, which is inconvenient to use in practice, and the calculation required to ensure the accuracy of the positioning algorithm is large, which is not conducive to real-time monitoring. Summary of the invention

[0005] The present invention solves the problem that the leakage source positioning scheme of the wall panel structure requires a large number of sensor arrays, which is inconvenient to use in practice, and the amount of calculation required to ensure the accuracy of the positioning algorithm is large, which is not conducive to real-time monitoring. A full-field positioning method for the leakage source of the far-field and near-field wall panel based on a linear acoustic array is proposed, which specifically includes:

[0006] Step 1: Determine the dispersion curve according to the structure and material of the wall panel to be detected, extract the main frequency of the signal, and determine the angle threshold according to the array structure and the two selected sub-arrays;

[0007] Step 2: Calculate the difference in positioning results of the two subarrays, and compare the difference in positioning results with the threshold;

[0008] Step 3: If the positioning result difference is not greater than the threshold, far-field positioning is performed, and the far-field positioning is completed using the full array and the far-field positioning result is output;

[0009] Step 4: If the positioning result difference is less than the threshold, near-field positioning is performed, and the improved 2Dmusic algorithm is used to process the full array signal to obtain the near-field positioning result.

[0010] Preferably, step 1 specifically includes:

[0011] Step 1.1: After receiving the acoustic emission signal from the leakage source, the linear acoustic array performs Fourier transform on the measurement signal of the reference array element to identify the energy of the acoustic emission signal from the leakage source in different frequency bands, wherein the acoustic emission signal from the leakage source is a broadband signal of (50-400) kHz;

[0012] Step 1.2: Use bandpass filtering to extract the 20kHz bandwidth signal with the largest energy as the measurement signal, where the center frequency of the measurement signal is w and the propagation speed is a constant v;

[0013] Step 1.3: Calculate the delay function of the i-th element of the linear array with an element spacing of d relative to the reference element under far-field conditions;

[0014] Step 1.4: Multiply the received signals of all channels of the linear acoustic array by the conjugate of the delay coefficient and sum them to obtain the signal strength received in all directions, and take the direction with the maximum received signal energy as the direction and angle threshold of the leakage source;

[0015] The expression of the delay function is:

[0016]

[0017] Preferably, the threshold calculation step in step 2 includes:

[0018] Step 2.1: Calculate the output of the subarray in the θ direction;

[0019] Step 2.2: Calculate and obtain different energy and angle correspondences based on the output of the subarray in the θ direction, and obtain the positioning results of the two subarrays;

[0020] Step 2.3: Calculate the positioning result difference of the two sub-arrays under the theoretical critical case when the far-field condition is met, and use the positioning result difference of the two sub-arrays under the theoretical critical case as the threshold. The far-field condition is that the distance between the leakage source and the reference array element is greater than

[0021]

[0022] The expression of the output of the subarray in the θ direction is:

[0023]

[0024] In formula (2), M is the number of sensor array elements;

[0025] The expression of the difference in positioning results of two subarrays under the theoretical critical condition is:

[0026]

[0027] In formula (3), x is the distance between the two sub-array reference elements, and D is the aperture of the entire sensor array.

[0028] Preferably, step 3 specifically includes:

[0029] When the far-field condition is met, the angle threshold of the full array is determined according to step 1, and the positioning result of the full array is obtained according to step 2, and the positioning result of the full array is output as the far-field positioning result.

[0030] Preferably, step 4 specifically includes:

[0031] Step 4.1: Use the improved 2Dmusic algorithm to convert variables θ and r into γ and φ, calculate the delay function matrix under near-field conditions, decompose the delay function matrix Ω(θ, r) to obtain the noise subspace Ω1(γ)Ω2(φ);

[0032] Step 4.2: Calculate the music power spectrum P(θ,r) based on the noise subspace;

[0033] Step 4.3: Use the power spectrum function to calculate the music power spectrum within the search range of the linear acoustic array, and introduce the matrix e1=(0,0…0,1) to transform the maximum value problem of P(θ,r) into a quadratic optimization problem in standard form;

[0034] Step 4.4: Use the Lagrange multiplier method to construct the cost function to solve the quadratic optimization problem;

[0035] Step 4.5: Adjust the cost function Find the partial derivative equal to zero to obtain the minimum value of the cost function, and Substitution Eliminate the unknown parameter η in the cost function in the partial derivative formula to obtain Ω2(φ);

[0036] Step 4.6: Substitute Ω2(φ) into the quadratic optimization problem and transform the maximum value problem of P(θ,r) into the maximum value problem of the single variable γ;

[0037] Step 4.7: Take the calculated music power spectrum P(θ,r) as a known condition, use the known condition to search for spectrum peaks for different γ to obtain the value of γ, repeat steps 4.1 to 4.6 to obtain the value of φ, and use the values ​​of θ and r as the position estimation results;

[0038] Step 4.8: Use the power spectrum function to perform a two-dimensional spectrum peak search within a limited range of ±10° and ±0.05m of the estimated position, and take the angle and distance corresponding to the maximum value as the near-field positioning result;

[0039] The expression of music power spectrum is:

[0040]

[0041] In formula (4), x(t) is the measurement signal matrix, * represents the conjugate transpose of the matrix, K is the number of snapshots, and U is S is the signal subspace composed of the largest eigenvalue, U N is the noise subspace composed of the remaining eigenvalues;

[0042] The expression of the power spectrum function is:

[0043]

[0044] In formula (5),

[0045] The expression of the quadratic optimization problem is:

[0046]

[0047] The expression of the cost function is:

[0048] L(γ,φ)=Ω2 * (φ)Q(γ)Ω2(φ)-η(e1 T Ω2(φ)-1) (7);

[0049] In formula (7), η is an unknown parameter;

[0050] right The expression for finding the partial derivative equal to zero is:

[0051]

[0052] The calculation formula of Ω2(φ) is:

[0053]

[0054] The calculation formula of the noise subspace Ω1(γ)Ω2(φ) is:

[0055]

[0056] Preferably, the calculation step of the delay function matrix under near-field conditions in step 4.1 includes:

[0057] Step 4.1.1: Calculate the difference between the distance from the received signal to the reference array element and the distance from the signal to any sub-array element;

[0058] Step 4.1.2: Taking the central array element as the reference array element, the delay function matrix under near-field conditions is calculated based on the distance difference;

[0059] The expression for the difference between the distance from the received signal to the reference array element and the distance from the signal to any array element is:

[0060]

[0061] In formula (11), n ​​is the number of intervals between the array element and the reference array element;

[0062] The expression of the delay function matrix under near-field conditions is:

[0063]

[0064] In formula (12), is the number of single-side sensor array elements, d is the interval between adjacent array elements, is a small first-order quantity in Δ, is a small second-order quantity in Δ.

[0065] The beneficial effects of the present invention are:

[0066] (1) The array structure used in the present invention is simple, and a single linear sensor array can achieve the function, which is easy to arrange and use.

[0067] (2) The present invention can expand the positioning range, preliminarily determine the range of the leakage source by analyzing the sub-array positioning results, and design a corresponding positioning method for the near-field situation, so that the system can maintain a high positioning accuracy under both far-field and near-field conditions.

[0068] (3) The algorithm used in the present invention has low complexity. An improved 2Dmusic algorithm is used in near-field positioning. The two-dimensional search is converted into two one-dimensional searches while ensuring accuracy. At the same time, there is no need to process multiple sensor array signals, thereby improving the real-time performance of the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 A schematic flow chart of a method for full-field positioning of a far-field and near-field wall panel leakage source based on a linear acoustic array provided by the present invention;

[0070] Figure 2The velocity-frequency dispersion curve of the aluminum alloy wall plate with a thickness of 2.5 mm provided by the present invention;

[0071] Figure 3 A schematic diagram of the position arrangement of the linear sensor array provided by the present invention;

[0072] Figure 4 A schematic diagram of the estimated signal source and 2D search range provided by the present invention;

[0073] Figure 5 A schematic diagram of angle and distance information of the near-field positioning result provided by the present invention. DETAILED DESCRIPTION

[0074] Combination Figure 1-5 To illustrate this embodiment, Figure 1 As shown, the steps of a full-field positioning method for a far-field and near-field wall panel leakage source based on a linear acoustic array described in this embodiment include:

[0075] S1: Determine the dispersion curve according to the structure and material of the detected wall panel, extract the main frequency of the signal, and determine the angle threshold according to the array structure and the two selected sub-arrays;

[0076] S101: In practice, the acoustic emission signal generated by the leakage source is a broadband signal of (50-400) kHz. There is a dispersion effect when the signal propagates in the wall panel, which causes different frequency components contained in the broadband signal to have different propagation speeds. In specific implementation, a certain frequency band in the broadband should be selected for measurement. The velocity-frequency dispersion curve of the aluminum alloy wall panel with a thickness of 2.5 mm selected in this embodiment is as follows: Figure 2 As shown in the figure, a leakage source signal with two main frequencies of 100 kHz and 200 kHz is simulated in the range of (50-400) kHz. The system selects the frequency band [90 kHz, 110 kHz] with larger energy for detection, and determines the corresponding propagation speed as 1430 m / s based on the dispersion curve.

[0077] After the array receives the signal, the signal received by the reference array element is Fourier transformed to identify the energy of different frequency bands, and then the 20kHz bandwidth signal with the largest energy is extracted by bandpass filtering as the measurement signal. The center frequency of the measurement signal is w, and the propagation speed changes little within the range of 20kHz, which can be regarded as a constant value v;

[0078] S102: Under the scenario described in S101, calculate the delay function of the i-th array element of the linear array with an array element spacing of d relative to the reference array element under far-field conditions;

[0079] The expression of the delay function is:

[0080]

[0081] S103: The received signals of all channels of the linear acoustic array are multiplied by the conjugate of the delay coefficient and summed, which can eliminate the influence of delay and noise and obtain the signal strength received in all directions. The direction with the maximum received signal energy is taken as the direction and angle threshold of the leakage source. The output of the array in the θ direction is:

[0082]

[0083] In formula (2), M is the number of sensor array elements.

[0084] S2: Calculate the positioning result difference of the two subarrays, and compare the positioning result difference with the threshold;

[0085] S201: Select two different sub-arrays, and use formula (2) to calculate different energy and angle correspondences to obtain two positioning results. When the distance between the leakage source and the reference array element is greater than When the far-field condition is satisfied, theoretically, the positioning result difference between the two sub-arrays in the far-field critical condition is:

[0086]

[0087] In formula (3), x is the distance between the two sub-array reference elements, and D is the aperture of the entire sensor array.

[0088] S202: Set the theoretical angle difference as a threshold, such as Figure 3 As shown, this embodiment selects the first five and the last five sensors as two sub-arrays for positioning. The angle threshold of 2.3° can be calculated from the array parameters and the selected sub-array. The leakage source signal is applied at a distance of 0.1m and 45° from the signal source using software. The positioning results of the two sub-arrays are shown in the figure. The positioning difference is 8.9°, which is higher than the angle threshold. It is considered that the leakage source position does not meet the far-field positioning conditions.

[0089] S3: If the positioning result difference is not greater than the threshold, far-field positioning is performed, and the far-field positioning is completed using the full array and the far-field positioning result is output;

[0090] When the far-field condition is met, the angle threshold of the entire array is determined according to S1, and the positioning result of the entire array is obtained according to S2, and the positioning result of the entire array is output as the far-field positioning result.

[0091] S4: If the positioning result difference is less than the threshold, near-field positioning is performed, and the improved 2Dmusic algorithm is used to process the full array signal to obtain the near-field positioning result.

[0092] S401: In positioning, the arrival wave of the near-field signal source is regarded as a spherical wave, and the difference between the distance of the signal reaching the reference array element and the distance of the signal reaching any array element is:

[0093]

[0094] In formula (4), n is the number of intervals between the array element and the reference array element;

[0095] S402: Taking the central array element as the reference array element, the delay function matrix under the near field condition is written as:

[0096]

[0097] In formula (5), is the number of single-side sensor array elements, d is the interval between adjacent array elements, is a small first-order quantity in Δ, is a small second-order quantity in Δ;

[0098] S403: Corresponding to the first-order small quantity and the second-order small quantity in Δ.

[0099] S403: If the near-field beamforming method is used, it is necessary to traverse every angle and distance in the near-field range, which requires a lot of calculation. In order to reduce the calculation complexity, this implementation adopts an improved 2Dmusic algorithm to achieve near-field positioning. The core of the algorithm is to convert variables θ and r into γ and φ, and obtain γ and φ through two one-dimensional searches based on the music power spectrum, so as to estimate θ and r, and decompose Ω(θ, r) into:

[0100]

[0101] S404: Use the measured signal to construct a covariance matrix and decompose it, extract the noise subspace and calculate the music power spectrum:

[0102]

[0103] In formula (7), x(t) is the measurement signal matrix, * represents the conjugate transpose of the matrix, K is the number of snapshots, and U is S is the signal subspace composed of the largest eigenvalue, U N is the noise subspace composed of the remaining eigenvalues;

[0104] S405: Calculating the music power spectrum within the search range of the linear acoustic array using a power spectrum function;

[0105] The expression of the power spectrum function is:

[0106]

[0107] In formula (8), Using formula (6), P(θ,r) can be further written as:

[0108]

[0109] In formula (9),

[0110] S406: At this time, finding the maximum value of P(θ, r) is equivalent to finding the maximum value of P(γ, φ). Introducing the matrix e1 = (0, 0…0, 1) can further write the maximum value problem into a quadratic optimization problem in standard form:

[0111]

[0112] S407: For the quadratic optimization problem, this embodiment uses the Lagrange multiplier method to construct a cost function to solve:

[0113] The expression of the cost function is:

[0114]

[0115] In formula (11), η is an unknown parameter;

[0116] S408: In order to minimize the cost function, this embodiment performs Find the partial derivative equal to zero:

[0117]

[0118] S409: Substituting into the above formula, we can eliminate η and get:

[0119]

[0120] Substitute formula (13) into formula (10) to eliminate φ, and transform the maximum value problem of P(θ,r) into the maximum value problem of the single variable γ. Use the known conditions to search for the spectrum peak of different γ to obtain the value of γ. Repeat S401-S409 to obtain the value of φ. The values ​​of θ and r are used as the position estimation results, as shown in Figure 4 As shown, the covariance matrix of the decomposed signal is used to obtain the noise subspace corresponding matrix. The location of the leakage source is estimated using the improved 2Dmusic algorithm. The distance and angle relative to the sensor array are 0.13m and 49°, as shown in Figure 5 As shown, a two-dimensional spectrum peak search is performed using a power spectrum function within a limited interval of ±10° and ±0.05m of the estimated position, and the angle and distance corresponding to the maximum value are taken as the near-field positioning result.

[0121] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A full-field positioning method for near- and far-field wall panel leakage sources based on a linear acoustic array, characterized in that: The steps of the full-field positioning method for far-field and near-field wall panel leakage sources based on a linear acoustic array include: Step 1: Determine the dispersion curve according to the structure and material of the wall panel to be detected, extract the main frequency of the signal, and determine the angle threshold according to the array structure and the two selected sub-arrays; Step 2: Calculate the difference in positioning results of the two subarrays, and compare the difference in positioning results with the threshold; Step 3: If the positioning result difference is not greater than the threshold, far-field positioning is performed, and the far-field positioning is completed using the full array and the far-field positioning result is output; Step 4: If the positioning result difference is less than the threshold, near-field positioning is performed, and the improved 2Dmusic algorithm is used to process the full array signal to obtain the near-field positioning result.

2. According to claim 1, a method for full-field positioning of far-field and near-field wall panel leakage sources based on a linear acoustic array is characterized in that: Step 1 specifically includes: Step 1.1: After receiving the acoustic emission signal from the leakage source, the linear acoustic array performs Fourier transform on the measurement signal of the reference array element to identify the energy of the acoustic emission signal from the leakage source in different frequency bands, wherein the acoustic emission signal from the leakage source is a broadband signal of (50-400) kHz; Step 1.2: Use bandpass filtering to extract the 20kHz bandwidth signal with the largest energy as the measurement signal, where the center frequency of the measurement signal is w and the propagation speed is a constant v; Step 1.3: Calculate the delay function of the i-th element of the linear array with an element spacing of d relative to the reference element under far-field conditions; Step 1.4: Multiply the received signals of all channels of the linear acoustic array by the conjugate of the delay coefficient and sum them to obtain the signal strength received in all directions, and take the direction with the maximum received signal energy as the direction and angle threshold of the leakage source; The expression of the delay function is:

3. According to claim 1, a method for full-field positioning of far-field and near-field wall panel leakage sources based on a linear acoustic array is characterized in that: The threshold calculation steps in step 2 include: Step 2.1: Calculate the output of the subarray in the θ direction; Step 2.2: Calculate and obtain different energy and angle correspondences based on the output of the subarray in the θ direction, and obtain the positioning results of the two subarrays; Step 2.3: Calculate the positioning result difference of the two sub-arrays under the theoretical critical case when the far-field condition is met, and use the positioning result difference of the two sub-arrays under the theoretical critical case as the threshold, where the far-field condition is that the distance between the leakage source and the reference array element is greater than The expression of the output of the subarray in the θ direction is: In formula (2), M is the number of sensor array elements; The expression of the difference in positioning results of two subarrays under the theoretical critical condition is: In formula (3), x is the distance between the two sub-array reference elements, and D is the aperture of the entire sensor array.

4. According to claim 1, a method for full-field positioning of far-field and near-field wall panel leakage sources based on a linear acoustic array is characterized in that: Step 3 specifically includes: When the far-field condition is met, the angle threshold of the full array is determined according to step 1, and the positioning result of the full array is obtained according to step 2, and the positioning result of the full array is output as the far-field positioning result.

5. According to claim 1, a method for full-field positioning of far-field and near-field wall panel leakage sources based on a linear acoustic array is characterized in that: Step 4 specifically includes: Step 4.1: Use the improved 2Dmusic algorithm to convert variables θ and r into γ and φ, calculate the delay function matrix under near-field conditions, decompose the delay function matrix Ω(θ, r) to obtain the noise subspace Ω1(γ)Ω2(φ); Step 4.2: Calculate the music power spectrum P(θ,r) based on the noise subspace; Step 4.3: Use the power spectrum function to calculate the music power spectrum within the search range of the linear acoustic array, and introduce the matrix e1=(0,0…0,1) to transform the maximum value problem of P(θ,r) into a quadratic optimization problem in standard form; Step 4.4: Use the Lagrange multiplier method to construct the cost function to solve the quadratic optimization problem; Step 4.5: Ω in the cost function * 2(φ) finds the partial derivative equal to zero to obtain the minimum value of the cost function, and e1 T Ω2(φ)=1Substitute into Ω * 2(φ) Eliminate the unknown parameter η in the cost function in the partial derivative formula to obtain Ω2(φ); Step 4.6: Substitute Ω2(φ) into the quadratic optimization problem and transform the maximum value problem of P(θ,r) into the maximum value problem of the single variable γ; Step 4.7: Take the calculated music power spectrum P(θ,r) as a known condition, use the known condition to search for spectrum peaks for different γ to obtain the value of γ, repeat steps 4.1 to 4.6 to obtain the value of φ, and use the values ​​of θ and r as the position estimation results; Step 4.8: Use the power spectrum function to perform a two-dimensional spectrum peak search within a limited range of ±10° and ±0.05m of the estimated position, and take the angle and distance corresponding to the maximum value as the near-field positioning result; The expression of music power spectrum is: In formula (4), x(t) is the measurement signal matrix, * represents the conjugate transpose of the matrix, K is the number of snapshots, and U is S is the signal subspace composed of the largest eigenvalues, U N is the noise subspace composed of the remaining eigenvalues; The expression of the power spectrum function is: In formula (5), The expression of the quadratic optimization problem is: The expression of the cost function is: In formula (7), η is an unknown parameter; right The expression for partial derivative equal to zero is: The calculation formula of Ω2(φ) is: The calculation formula of the noise subspace Ω1(γ)Ω2(φ) is:

6. The method for full-field positioning of far-field and near-field wall panel leakage sources based on a linear acoustic array according to claim 5 is characterized in that: The calculation steps of the delay function matrix under near-field conditions in step 4.1 include: Step 4.1.1: Calculate the difference between the distance from the received signal to the reference array element and the distance from the signal to any sub-array element; Step 4.1.2: Taking the central array element as the reference array element, the delay function matrix under near-field conditions is calculated based on the distance difference; The expression for the difference between the distance from the received signal to the reference array element and the distance from the signal to any array element is: In formula (11), n ​​is the number of intervals between the array element and the reference array element; The expression of the delay function matrix under near-field conditions is: In formula (12), is the number of single-side sensor array elements, d is the interval between adjacent array elements, is a small first-order quantity in Δ, is a small second-order quantity in Δ.

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