A Lamb wave temperature compensation method, system, device and medium

Abstract

The present invention belongs to the technical field related to ultrasonic structural monitoring. To solve the problem of inaccurate temperature compensation of Lamb waves, a Lamb wave temperature compensation method, system, device, and medium are proposed. The optimal reference temperature range of the guided wave to be compensated is determined by using the non-linear correlation coefficient, and the temperature of a more accurate detection signal can be obtained. An adaptive compensation path for the guided wave is proposed to be dynamically adjusted according to the position of the detection signal temperature in the optimal reference temperature range, which can solve the problem of phase over-compensation in the direct path compensation technology, with higher compensation accuracy. Subsequently, based on the high-precision guided wave temperature compensation result, an accurate positioning result can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field related to ultrasonic structural monitoring, and in particular, relates to a Lamb wave temperature compensation method, system, device and medium. Background Art

[0002] The statements herein only provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Due to advantages such as wide detection range and high sensitivity, the structural health monitoring technology based on Lamb waves has been widely applied in fields such as aerospace and rail transit. However, environmental temperature fluctuations can cause changes in the elastic modulus of materials, resulting in changes in the propagation speed of Lamb waves and generating a phase delay effect. Experimental studies have shown that for every 10°C increase in temperature, the propagation time offset of Lamb waves in typical metal structures can reach 1 - 3 μs. This time shift magnitude is comparable to the signal changes caused by early damage, seriously interfering with the decoupling of damage characteristics.

[0004] Existing temperature compensation technologies are mainly divided into two categories: The first category is the compensation method based on neural networks, which realizes phase correction by constructing a temperature-signal mapping model. This type of method requires collecting a large number (usually more than 20 groups) of standard sample data at different temperatures for network training. However, for special structures such as embedded sensor networks or closed industrial equipment, it is difficult to conduct multi-condition temperature excitation experiments, resulting in limited practical engineering applications. The second category is the single-path compensation method based on the optimal reference temperature, which uses the Time domain warping (TDW) technology to directly align the damage signal to the reference temperature signal. However, this method ignores the non-linear relationship between temperature changes and signal distortion. When the temperature to be measured is significantly different from the reference temperature, direct path matching will lead to over-compensation phenomena such as waveform stretching / compression, manifested as widened signal envelopes and blurred phase characteristics after compensation. Existing results show that when the temperature difference exceeds 30°C, the damage recognition error will increase by more than 40%.

[0005] The reasons are as follows. There are two key defects in the existing technology: First, the linear compensation assumption under a single reference temperature does not match the actual non-linear characteristics of the temperature-sound speed relationship, especially in the wide temperature range working conditions, there are significant deviations in the compensation path. Second, the calculation of the compensation path lacks dynamic adaptability to temperature intervals and cannot optimize the matching strategy according to the relative position of the temperature to be measured in the reference temperature interval. The above problems have become technical bottlenecks restricting the engineering application of Lamb wave temperature compensation technology, and there is an urgent need for a temperature compensation method that takes into account both compensation accuracy and data acquisition feasibility. Summary of the Invention

[0006] To overcome the deficiencies of the above-mentioned existing technologies, the present invention provides a Lamb wave temperature compensation method, system, device, and medium, which are based on a dynamic time warping temperature compensation method with optimal temperature range matching and have higher compensation accuracy.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a Lamb wave temperature compensation method, including:

[0009] Collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non-linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set;

[0010] Sort the calculated non-linear correlation coefficients from largest to smallest, and use the temperatures corresponding to the top two ranked non-linear correlation coefficients as the endpoint values of the optimal reference temperature range, and calculate the temperature pre-estimation value of the guided wave signal to be compensated;

[0011] According to the positional relationship between the temperature pre-estimation value and the endpoint values of the optimal reference temperature range, combined with the time-domain warping algorithm, determine the optimal matching path;

[0012] Perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

[0013] In the second aspect, the present invention provides a Lamb wave temperature compensation system, including:

[0014] A calculation module, which is configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non-linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set;

[0015] A sorting module, which is configured to: sort the calculated non-linear correlation coefficients from largest to smallest, and use the temperatures corresponding to the top two ranked non-linear correlation coefficients as the endpoint values of the optimal reference temperature range, and calculate the temperature pre-estimation value of the guided wave signal to be compensated;

[0016] An optimal matching path module, which is configured to: according to the positional relationship between the temperature pre-estimation value and the endpoint values of the optimal reference temperature range, combined with the time-domain warping algorithm, determine the optimal matching path;

[0017] A temperature compensation module, which is configured to: perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

[0018] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in the first aspect is completed.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the method described in the first aspect is completed.

[0020] The above one or more technical solutions have the following beneficial effects:

[0021] In the present invention, a non-linear correlation coefficient is used to determine the optimal reference temperature range of the guided wave to be compensated, and the temperature of the detection signal can be obtained more accurately. An adaptive compensation path for the guided wave is proposed to be dynamically adjusted according to the position of the detection signal temperature in the optimal reference temperature range, which can solve the problem of phase over-compensation in the direct path compensation technology, with higher compensation accuracy. Subsequently, based on the high-precision guided wave temperature compensation result, an accurate positioning result can be obtained.

[0022] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0024] Figure 1 It is a flowchart of a Lamb wave temperature compensation method in Embodiment 1 of the present invention;

[0025] Figure 2 It is a schematic diagram of calculating a matching path by the TDW algorithm in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0028] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0029] Embodiment 1

[0030] This embodiment discloses a Lamb wave temperature compensation method, including:

[0031] Collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non - linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set;

[0032] Sort the calculated non - linear correlation coefficients from largest to smallest, and use the temperatures corresponding to the top two non - linear correlation coefficients in the sorting result as the endpoint values of the optimal reference temperature range;

[0033] Calculate the temperature prediction value of the guided wave signal to be compensated according to the endpoint values of the optimal reference temperature range and their corresponding non - linear correlation coefficients;

[0034] Determine the optimal matching path according to the positional relationship between the temperature prediction value and the endpoint values of the optimal reference temperature range, in combination with the time - domain bending algorithm;

[0035] Perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

[0036] The solution of this embodiment can obtain a more accurate temperature of the detection signal by using the non - linear correlation coefficient, and further obtain a more accurate adaptive compensation path. The adaptive path compensation path can dynamically adjust the temperature compensation path of the guided wave according to the position of the detection signal temperature in the reference temperature range, which can solve the problem of phase over - compensation in the diameter path compensation technology and has higher compensation accuracy. Based on the high - precision guided wave temperature compensation result, an accurate positioning result can be obtained.

[0037] In this embodiment, first, a Lamb wave signal acquisition experimental system is built for Lamb wave signal acquisition. The Lamb wave signal acquisition experimental system includes a piezoelectric sensor array, an aluminum alloy plate, an ultrasonic guided wave acquisition device, a host computer, and a thermostat. Among them, the piezoelectric sensor array is composed of 12 piezoelectric ceramic sensors. The piezoelectric ceramic sensors are attached to the aluminum alloy plate through AB epoxy adhesive, and are mainly responsible for the excitation and reception of lamb waves at a specific frequency. The structure of the aluminum alloy plate is the structure to be detected for damage. The ultrasonic guided wave acquisition device, as the connection bridge between the piezoelectric sensor array and the host computer, is responsible for the transmission of exciting lamb waves and receiving lamb signals, and has functions such as signal generation, power amplification, high - speed acquisition, and band - pass filtering. The host computer can realize the setting of detection device parameters, the generation of excitation signals, the real - time display of received guided wave signals, and data storage. The thermostat is mainly responsible for changing the environmental temperature of the aluminum alloy structure. The specific implementation process is to place the aluminum alloy structure (including the piezoelectric sensor array pasted on its surface) in the thermostat, and change the temperature of the aluminum alloy structure by adjusting the set value of the thermostat temperature.

[0038] It should be noted that the above is not limited to the aluminum alloy flat structure, and other structures that can be realized are also acceptable.

[0039] Under the healthy state of the aluminum alloy structure (that is, no damage is set on the surface of the structure), guided waves are used to collect the guided wave signals at temperatures T1, T2, …, Tn respectively, and the guided wave signals at the above n temperatures collected by the experimental system are marked as the reference signal set [X T1 , X T2 , …, X Tn .

[0040] In this embodiment, the Spearman correlation coefficients between the guided wave signal Y to be compensated and each guided wave signal in the reference signal set are calculated respectively through formula (1).

[0041] (1)

[0042] Among them, the parameter N m is the number of sensing paths arranged in the experimental system; M is the signal length of the signal to be compensated or the reference signal; d i is the rank difference of the data between the guided wave signal to be compensated and the reference signal.

[0043] Mark the reference temperatures corresponding to the maximum value and the second maximum value of the non - linear correlation coefficient as T H and T L , T H >T L , and the reference signals X H and X L corresponding to the temperatures T TH and X TL are the optimal interval reference signals, [T L , T H is the optimal reference temperature interval. At this time, the temperature pre - estimate value T D of the guided wave signal to be compensated can be further obtained according to formula (2).

[0044] (2)

[0045] Among them, N m is the number of sensing paths arranged in the experimental system, ρ H and ρ L are respectively the guided wave signal to be compensated Y and the reference signal X TH , the reference signalX TL The non-linear correlation coefficient between

[0046] According to T D and the temperature T H 、temperature T L Based on the positional relationship between them, combined with the time-domain bending algorithm, determine the optimal matching path W = γ*W 0, where γ and W O represent the path compensation coefficient and the initial matching path respectively, and can be calculated by equations (3) and (4) respectively:

[0047] (3)

[0048] (4)

[0049] Where W H→L represents the initial matching path obtained by using the TDW algorithm with X TL as the reference signal and X TH as the signal to be matched; W L→H represents the initial matching path obtained by using the TDW algorithm with X TH as the reference signal and X TL as the signal to be matched, represents the initial matching path. X TH represents the guided wave signal at the higher temperature T H in the reference temperature range, and X TL represents the guided wave signal at the lower temperature T L in the reference temperature range.

[0050] Based on the compensation path W and the guided wave signal Y to be compensated, use the time-domain bending algorithm to calculate the damage temperature compensation signal Y D .

[0051] Time-domain Warping (TDW) is an optimization algorithm commonly used for time series matching. Its principle is to construct a series of non-linear time mapping functions using dynamic programming or gradient descent optimization algorithms to match two signals on the time axis.

[0052] The following takes using time-domain bending with X TH as the reference signal and X TL as the initial matching path of the signal to be matched W L→H as an example for illustration:

[0053] Such as Figure 2As shown, let X TH = x 1, x 2, …, x n and X TL = y 1, y 2, …, y m be the reference signal and the signal to be matched respectively. First, construct a n × m -dimensional matrix D to represent the Euclidean distance between the reference signal X TH and the signal to be matched X TL . Any element (1 ≤ i ≤ n , 1 ≤ j ≤ m ) in the matrix; then, calculate the cumulative distance matrix C n×m according to Equation (5), where the parameter β（β ≥ 1 ） is a bending coefficient introduced to avoid signal overcompensation to perform a non-linear constraint on the signal.

[0054] (5)

[0055] After obtaining the cumulative distance matrix C , start backtracking along the minimum path from the last element c nm of the matrix to c 11 . The selection principle for each element on the minimum path is: if c ij is an element on the minimum path, then the next element on the path is the smallest one among c (i-1)j , c i(j-1) , c (i-1)(j-1) , and so on, to obtain the minimum path P from the element C to c nm in the cumulative distance matrix c 11 .

[0056] At this time, the non-linear mapping matrix W = [W1, W2, …, W TH between the reference signal X TL and the signal to be matched X q (max( n , m ) ≤q ≤ 2 n +1), which is the row and column number set of each element on the minimum path P. Any variable W in the matrix k = i k , j k represents the data in the k-th column of W. i k , j k represents the TH th element in X x ik matching the TL th element in X y jk , that is: assign y jk as the damage temperature compensation signal Y D th element in i k . Then the damage temperature compensation signal Y of the original signal matching the reference signal X TH can be obtained. Among them, Y D is the damage temperature compensation signal obtained by operating on Y according to each element in the mapping matrix W. D If there are multiple elements in the signal X to be matched assigned to the same element in the damage temperature compensation signal Y

[0057] TL , the corresponding elements in the signal X to be matched should be averaged and then assigned to the damage temperature compensation signal Y D . TL D

[0058] . Using the non-linear correlation coefficient and the root mean square error as evaluation indicators, the results obtained from the experiments carried out show that the guided wave compensation signal obtained by using the adaptive compensation technology has an average increase of 8% in the correlation coefficient with the reference signal compared with the uncompensated signal, and a decrease of 74% in the root mean square error index.

[0059] Embodiment 2

[0060] The purpose of this embodiment is to provide a Lamb wave temperature compensation system, including:

[0061]

[0062] The first calculation module is configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non-linear correlation coefficient between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set;​​A sorting module, configured to: sort the calculated non-linear correlation coefficients from largest to smallest, and use the temperatures corresponding to the top two ranked non-linear correlation coefficients as the endpoint values of the optimal reference temperature range according to the sorting result;

[0063] A second calculation module, configured to: calculate a temperature prediction value of the guided wave signal to be compensated according to the endpoint values of the optimal reference temperature range and the corresponding non-linear correlation coefficients;

[0064] An optimal matching path module, configured to: determine an optimal matching path according to the positional relationship between the temperature prediction value and the endpoint values of the optimal reference temperature range, in combination with the time domain bending algorithm;

[0065] A temperature compensation module, configured to: perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

[0066] In more embodiments, there is also provided:

[0067] An electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in Embodiment 1 is completed. For the sake of brevity, it will not be elaborated here.

[0068] It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0069] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A part of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0070] A computer-readable storage medium, for storing computer instructions, which when executed by the processor, complete the method described in Embodiment 1.

[0071] The method in Embodiment 1 can be directly implemented by a hardware processor to complete, or implemented by a combination of hardware and software modules in the processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0072] A computer program product includes a computer program which, when executed by a processor, implements the method described in the first embodiment.

[0073] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which are executed in a device on a target real or virtual processor to perform the processes / methods described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or divided as needed. Machine-executable instructions for program modules can be executed within local or distributed devices. In a distributed device, program modules can be located in local and remote storage media.

[0074] The computer program code for implementing the method of the present invention can be written in one or more programming languages. This computer program code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the program code is executed by the computer or other programmable data processing device, the functions / operations specified in the flowchart and / or block diagram are implemented. The program code can be executed entirely on the computer, partially on the computer, as a stand-alone software package, partially on the computer and partially on a remote computer, or entirely on a remote computer or server.

[0075] In the context of the present invention, the computer program code or related data can be carried by any suitable carrier so that the device, apparatus, or processor can perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc. Examples of signals can include electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, etc.

[0076] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in conjunction with this embodiment can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0077] Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A Lamb wave temperature compensation method, characterized in that, Including: Collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non - linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set; Sort the calculated non - linear correlation coefficients from largest to smallest. According to the sorting result, take the temperatures corresponding to the top two non - linear correlation coefficients as the endpoint values of the optimal reference temperature range, and calculate the temperature pre - estimate value of the guided wave signal to be compensated. Specifically: ， Among them, N m is the number of sensing paths arranged, ρ H and ρ L are the non - linear correlation coefficients between the guided - wave signal to be compensated and signal X TH , signal X TL respectively; signal X TH , signal X TL are the reference signals corresponding to the endpoint values of the optimal reference temperature range respectively; According to the positional relationship between the temperature pre - estimate value and the endpoint values of the optimal reference temperature range, combined with the time - domain bending algorithm, determine the optimal matching path; Perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

2. The Lamb wave temperature compensation method according to claim 1, wherein Use the Spearman method to calculate the non - linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set.

3. The Lamb wave temperature compensation method according to claim 1, characterized in that According to the positional relationship between the temperature pre - estimate value and the endpoint values of the optimal reference temperature range, combined with the time - domain bending algorithm, determine the optimal matching path. Specifically: W= γ*W 0 Among them, N m is the number of sensing paths arranged, ρ H and ρ L are the non - linear correlation coefficients between the guided - wave signal to be compensated and signal X TH 、signal X TL respectively; Signals X TH 、signal X TL are the reference signals corresponding to the endpoint values of the optimal reference temperature range respectively, T H and T L are the endpoint values of the optimal reference temperature range, W is the optimal matching path, W H→L represents the initial matching path obtained by using the time - domain bending algorithm with X TL as the reference signal and X TH as the signal to be matched; W L→H represents the initial matching path obtained by using the time - domain bending algorithm with X TH as the reference signal and X TL as the signal to be matched, represents the initial matching path.

4. The Lamb wave temperature compensation method according to claim 3, characterized in that, Use the time - domain bending algorithm to obtain the initial matching path of the signal to be matched. Specifically: Calculate the cumulative distance matrix of the reference signal and the signal to be matched; Start from the last element in the cumulative distance matrix and backtrack along the minimum path to the first element in the cumulative distance matrix to obtain the non - linear mapping matrix between the reference signal and the signal to be matched; According to the non - linear mapping matrix, obtain the damage temperature compensation signal.

5. The Lamb wave temperature compensation method according to claim 4, wherein The selection principle for each element on the minimum path is: if c ij is an element on the minimum path, then the next element on the path is c (i-1)j , c i(j-1) , c (i-1)(j-1) the smallest one among them, and so on, to obtain the minimum path from the element c nm to c 11 in the cumulative distance matrix.

6. The Lamb wave temperature compensation method according to claim 4, wherein Any variable in the non-linear mapping matrix indicates that the reference signal matches the signal to be matched, that is, the y jk element is assigned to the i k element in the damage temperature compensation signal. If multiple elements in the signal to be matched are assigned to the same element in the damage temperature compensation signal, the corresponding elements in the signal to be matched are averaged and then assigned to the damage temperature compensation signal.

7. A Lamb wave temperature compensation system, characterized in that, Including: A calculation module, configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate the non - linear correlation coefficients between the guided wave signal to be compensated and each Lamb wave signal in the reference signal set; A sorting module, configured to: sort the calculated non - linear correlation coefficients from largest to smallest. According to the sorting result, take the temperatures corresponding to the top two non - linear correlation coefficients as the endpoint values of the optimal reference temperature range, and calculate the temperature pre - estimate value of the guided wave signal to be compensated. Specifically: ， Wherein, N m is the number of sensing paths arranged, ρ H and ρ L are respectively the non - linear correlation coefficients between the guided - wave signal to be compensated and signal X TH , signal X TL ; signals X TH , signal X TL are respectively the reference signals corresponding to the endpoint values of the optimal reference temperature range; An optimal matching path module, configured to: according to the positional relationship between the temperature pre - estimate value and the endpoint values of the optimal reference temperature range, combined with the time - domain bending algorithm, determine the optimal matching path; A temperature compensation module, configured to: perform temperature compensation on the guided wave signal to be compensated based on the optimal matching path.

8. An electronic device, characterized in that, Including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method according to any one of claims 1 - 6 is completed.

9. A computer-readable storage medium, characterized in that, For storing computer instructions, when the computer instructions are executed by the processor, the method according to any one of claims 1 - 6 is completed.

Images