Lamb wave temperature compensation method, system, equipment and medium

Abstract

The invention belongs to the related technical field of ultrasonic structure monitoring, and provides a Lamb wave temperature compensation method, system, equipment and medium in order to solve the problem that Lamb wave temperature compensation is not accurate, the optimal reference temperature interval of guided waves to be compensated is determined by adopting nonlinear correlation coefficients, the temperature of a more accurate detection signal can be obtained, and the accuracy of Lamb wave temperature compensation is improved. A self-adaptive compensation path for dynamically adjusting the guided wave according to the position of the detection signal temperature in the optimal reference temperature interval is provided, the problem of phase overcompensation in a direct path compensation technology can be solved, the compensation precision is higher, and a precise positioning result can be obtained subsequently based on a high-precision guided wave temperature compensation result.

Description

Technical Field

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

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

[0003] Structural health monitoring technology based on Lamb waves has been widely used in aerospace, rail transit and other fields due to its advantages such as wide detection range and high sensitivity. However, ambient temperature fluctuations can cause changes in the elastic modulus of the material, resulting in changes in the propagation speed of the Lamb wave and a phase delay effect. Experimental studies have shown that for every 10°C increase in temperature, the propagation time of the Lamb wave in a typical metal structure can shift by 1-3μs. This time shift is comparable to the signal change caused by early damage, which seriously interferes with the decoupling of damage characteristics.

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

[0005] The reason is that the existing technology has two key defects: first, the linear compensation assumption under a single reference temperature does not match the actual nonlinear characteristics of the temperature-speed of sound relationship, especially under wide temperature range conditions, there is a significant deviation in the compensation path; second, the compensation path calculation lacks dynamic adaptability of the temperature range, and it is impossible to optimize the matching strategy according to the relative position of the measured temperature in the reference temperature range. The above problems have become the technical bottleneck restricting the engineering application of Lamb wave temperature compensation technology, and a temperature compensation method that takes into account both compensation accuracy and data acquisition feasibility is urgently needed. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a Lamb wave temperature compensation method, system, device and medium, which is based on a dynamic time bending temperature compensation method for optimal temperature range matching and has higher compensation accuracy.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a Lamb wave temperature compensation method, comprising: Collecting Lamb wave signals at different temperatures as a reference signal set, and calculating a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; The calculated nonlinear correlation coefficients are sorted from large to small, and according to the sorting result, the temperatures corresponding to the top two nonlinear correlation coefficients are used as the endpoint values ​​of the optimal reference temperature interval, and the temperature estimation value of the waveguide signal to be compensated is calculated; Determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; Temperature compensation is performed on the waveguide signal to be compensated based on the optimal matching path.

[0008] In a second aspect, the present invention provides a Lamb wave temperature compensation system, comprising: A calculation module is configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; A sorting module is configured to: sort the calculated nonlinear correlation coefficients from large to small, take the temperatures corresponding to the top two nonlinear correlation coefficients as the endpoint values ​​of the optimal reference temperature interval according to the sorting result, and calculate the temperature estimate of the waveguide signal to be compensated; An optimal matching path module is configured to: determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; A temperature compensation module is configured to perform temperature compensation on the waveguide signal to be compensated based on the optimal matching path.

[0009] In a third aspect, the present invention provides an electronic device comprising a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method described in the first aspect is performed.

[0010] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions, wherein when the computer instructions are executed by a processor, the method described in the first aspect is performed.

[0011] One or more of the above technical solutions have the following beneficial effects: In the present invention, a nonlinear correlation coefficient is used to determine the optimal reference temperature interval of the waveguide to be compensated, so that a more accurate temperature of the detection signal can be obtained. An adaptive compensation path for dynamically adjusting the waveguide according to the position of the detection signal temperature in the optimal reference temperature interval is proposed, 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 waveguide temperature compensation result, an accurate positioning result can be obtained.

[0012] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0014] Figure 1 This is a flow chart of a Lamb wave temperature compensation method in Embodiment 1 of the present invention; Figure 2 The figure is a schematic diagram of the matching path calculated by the TDW algorithm in the first embodiment of the present invention. DETAILED DESCRIPTION

[0015] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0016] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0017] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0018] Embodiment 1 This embodiment discloses a Lamb wave temperature compensation method, including: Collecting Lamb wave signals at different temperatures as a reference signal set, and calculating a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; The calculated nonlinear correlation coefficients are sorted from large to small, and the temperatures corresponding to the top two nonlinear correlation coefficients are used as the endpoint values ​​of the optimal reference temperature interval according to the sorting result; Calculating a temperature estimation value of the waveguide signal to be compensated according to the endpoint value of the optimal reference temperature interval and the corresponding nonlinear correlation coefficient; Determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; Temperature compensation is performed on the waveguide signal to be compensated based on the optimal matching path.

[0019] The present embodiment adopts a nonlinear correlation coefficient to obtain a more accurate temperature of the detection signal, and further obtains a more accurate adaptive compensation path. The adaptive path compensation path can dynamically adjust the temperature compensation path of the waveguide according to the position of the detection signal temperature in the reference temperature interval, which can solve the problem of phase overcompensation in the diameter path compensation technology, and the compensation accuracy is higher. Based on the high-precision waveguide temperature compensation result, an accurate positioning result can be obtained.

[0020] In this embodiment, a Lamb wave signal acquisition experimental system is first built for Lamb wave signal acquisition; wherein, 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 constant temperature box; wherein, the piezoelectric sensor array is composed of 12 piezoelectric ceramic sensors, which are attached to the aluminum alloy plate through AB epoxy adhesive and are mainly responsible for the excitation and reception of lamb waves at specific frequencies. The aluminum alloy plate structure is a structure to be damaged and detected. The ultrasonic guided wave acquisition device serves as a connecting bridge between the piezoelectric sensor array and the host computer, and is responsible for the transmission of the excitation lamb wave and the reception lamb signal, and has functions such as signal generation, power amplification, high-speed acquisition, and bandpass filtering. The host computer can realize the setting of detection equipment parameters, the generation of excitation signals, and the real-time display and data storage of received guided wave signals. The thermostat is mainly responsible for changing the ambient temperature of the aluminum alloy structure. The specific implementation process is to place the aluminum alloy structure (including the piezoelectric sensor array attached to its surface) in the thermostat, and change the temperature of the aluminum alloy structure by adjusting the set value of the thermostat temperature.

[0021] It should be noted that the above is not limited to the aluminum alloy flat plate structure, and other achievable structures are also possible.

[0022] When the aluminum alloy structure is in a healthy state (i.e., there is no damage on the surface of the structure), the guided wave signals at temperatures T1, T2, ..., Tn are collected by waveguide, and the guided wave signals at the above n temperatures collected by the experimental system are marked as the reference signal set [X T1 ,XT2 ,…,X Tn ].

[0023] In this embodiment, the Spearman correlation coefficients between the waveguide signal Y to be compensated and each waveguide signal in the reference signal set are calculated respectively by formula (1).

[0024] (1) Among them, the parameters N m The number of sensor paths laid out 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 between the data in the waveguide signal to be compensated and the reference signal.

[0025] The reference temperatures corresponding to the maximum and second largest values ​​of the nonlinear correlation coefficient are marked as T according to the temperature values. H With T L , T H >T L , and temperature T H With T L The corresponding reference signal X TH With X TL That is the optimal interval reference signal, [T L , T H ] is the optimal reference temperature range. At this time, the temperature estimation value T of the waveguide signal to be compensated can be further obtained according to formula (2): D .

[0026] (2) in, N m is the number of sensor paths laid out in the experimental system, r H and r L are the waveguide signals to be compensated Y With reference signal X TH , reference signal X TL The nonlinear correlation coefficient between .

[0027] According to T D With temperature T H , Temperature T L The position relationship between them is combined with the time domain bending algorithm to determine the optimal matching path W= c*W 0, where c and W ORespectively represent the path compensation coefficient and the initial matching path, which can be calculated by equation (3) and equation (4) respectively: (3) (4) in, W H→L Represents the use of TDW algorithm to obtain X TL is the reference signal, X TH is the initial matching path of the signal to be matched; W L→H Represents the use of TDW algorithm to obtain X TH is the reference signal, X TL is the initial matching path of the signal to be matched, Represents the initial matching path. X TH Represents the higher temperature T in the reference temperature range H The waveguide signal under X TL Represents the lower temperature T in the reference temperature range L The following waveguide signal.

[0028] Based on the compensation path W and the waveguide signal to be compensated Y, the damage temperature compensation signal is calculated using the time domain bending algorithm Y D .

[0029] Time-domain Warping (TDW) is an optimization algorithm commonly used for time series matching. Its principle is to use dynamic programming or gradient descent optimization algorithm to construct a series of nonlinear time mapping functions to match two signals on the time axis.

[0030] Next, we use time domain bending to TH is the reference signal, X TL is the initial matching path of the signal to be matched W L→H Take this as an example to illustrate: like Figure 2 As shown, let X TH =[ x 1, x 2, …, x n ] and X TL =[ y 1, y 2, …, y m ] are the reference signal and the signal to be matched respectively. First, we construct a n × m Dimensional matrix D To represent the reference signal X THand the signal to be matched X TL The Euclidean distance of any element in the matrix (1≤ i ≤ n , 1≤ j ≤ m ); Then, the cumulative distance matrix is ​​calculated according to formula (5) C n×m , where the parameter β（β ≥ 1 ） The bending coefficient is introduced to avoid signal overcompensation and to impose nonlinear constraints on the signal.

[0031] (5) In the cumulative distance matrix C Then, from the last element of the matrix c nm Start backtracking along the minimum path to c 11 , the selection principle of 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 get the cumulative distance matrix C Medium Element c nm arrive c 11 The minimum path P.

[0032] At this time, the reference signal X TH And the signal to be matched X TL The nonlinear mapping matrix W=[W1,W2,…,W 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 of the kth column in W, [ i k , j k ] indicates X TH The x ik Elements and X TLThe y jk elements, that is: y jk Assigned as damage temperature compensation signal Y D The i k elements, we can get the same signal as the reference signal X TH The damage temperature compensation signal Y of the matched original signal D Among them, Y D is the damage temperature compensation signal obtained by operating Y according to each element in the mapping matrix W.

[0033] If a matching signal X occurs TL Multiple elements in are assigned as damage temperature compensation signal Y D In the case of the same element in TL The corresponding elements in the averaging are then assigned to the damage temperature compensation signal Y D .

[0034] The nonlinear correlation coefficient and root mean square error are used as evaluation indicators. The results of the experiments show that the correlation coefficient between the waveguide compensation signal obtained by adaptive compensation technology and the reference signal is improved by 8% on average, and the root mean square error is reduced by 74% compared with the uncompensated signal.

[0035] Embodiment 2 The purpose of this embodiment is to provide a Lamb wave temperature compensation system, comprising: A first calculation module is configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; A sorting module is configured to: sort the calculated nonlinear correlation coefficients from large to small, and according to the sorting result, use the temperatures corresponding to the top two nonlinear correlation coefficients as the endpoint values ​​of the optimal reference temperature interval; A second calculation module is configured to calculate a temperature estimation value of the waveguide signal to be compensated according to the endpoint value of the optimal reference temperature interval and the corresponding nonlinear correlation coefficient; An optimal matching path module is configured to: determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; A temperature compensation module is configured to perform temperature compensation on the waveguide signal to be compensated based on the optimal matching path.

[0036] In further embodiments, there is also provided: An electronic device includes a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method described in Embodiment 1 is performed. For the sake of brevity, no further description is given here.

[0037] 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.

[0038] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0039] A computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the method described in embodiment 1 is completed.

[0040] The method in the first embodiment can be directly embodied as a hardware processor, or a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the field 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. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.

[0041] A computer program product includes a computer program, and when the computer program is executed by a processor, the method described in the first embodiment is implemented.

[0042] 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 a program module, which are executed in a device on a real or virtual processor of the target to perform the process / method as described above. Typically, 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 between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0043] The computer program code for implementing the method of the present invention can be written in one or more programming languages. These computer program codes can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the computer or other programmable data processing device, causes the function / operation specified in the flow chart and / or block diagram to be implemented. The program code can be executed completely on a computer, partially on a computer, as an independent software package, partially on a computer and partially on a remote computer or completely on a remote computer or server.

[0044] In the context of the present invention, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform the various processes and operations described above. Examples of carriers include signals, computer readable media, etc. Examples of signals may include electrical, optical, radio, acoustic or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0045] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0046] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A Lamb wave temperature compensation method, characterized in that: include: Collecting Lamb wave signals at different temperatures as a reference signal set, and calculating a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; The calculated nonlinear correlation coefficients are sorted from large to small, and according to the sorting result, the temperatures corresponding to the top two nonlinear correlation coefficients are used as the endpoint values ​​of the optimal reference temperature interval, and the temperature estimation value of the waveguide signal to be compensated is calculated; Determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; Temperature compensation is performed on the waveguide signal to be compensated based on the optimal matching path.

2. A Lamb wave temperature compensation method as claimed in claim 1, characterized in that: The Spearman method is used to calculate the nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set.

3. A Lamb wave temperature compensation method as claimed in claim 1, characterized in that: According to the endpoint value of the optimal reference temperature interval and the corresponding nonlinear correlation coefficient, the temperature estimation value of the waveguide signal to be compensated is calculated, specifically: ， in, N m is the number of sensor paths deployed, ρ H and ρ L are the waveguide signal and signal to be compensated respectively X TH ,Signal X TL The nonlinear correlation coefficient between the signals X TH ,Signal X TL They are the reference signals corresponding to the endpoint values ​​of the optimal reference temperature range.

4. A Lamb wave temperature compensation method as claimed in claim 1, characterized in that: According to the positional relationship between the temperature estimation value and the endpoint value of the optimal reference temperature interval, combined with the time domain bending algorithm, the optimal matching path is determined, specifically: W= γ*W 0 in, N m is the number of sensor paths deployed, ρ H and ρ L are the waveguide signal and signal to be compensated respectively X TH ,Signal X TL The nonlinear correlation coefficient between the signals X TH ,Signal X TL are the reference signals corresponding to the endpoint values ​​of the optimal reference temperature range, T H and T L is the endpoint value of the optimal reference temperature range, W is the optimal matching path, W H→L Represents the use of time domain bending algorithm to obtain X TL is the reference signal, X TH is the initial matching path of the signal to be matched; W L→H Represents the use of time domain bending algorithm to obtain X TH is the reference signal, X TL is the initial matching path of the signal to be matched, Represents the initial matching path.

5. A Lamb wave temperature compensation method as claimed in claim 4, characterized in that: The initial matching path of the signal to be matched is obtained by using the time domain warping algorithm, specifically: Calculate the cumulative distance matrix between the reference signal and the signal to be matched; Starting from the last element in the cumulative distance matrix, trace back along the minimum path to the first element in the cumulative distance matrix to obtain a nonlinear mapping matrix between the reference signal and the signal to be matched; According to the nonlinear mapping matrix, a damage temperature compensation signal is obtained.

6. A Lamb wave temperature compensation method as claimed in claim 5, characterized in that: The selection principle of each element on the minimum path is: 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 get the element in the cumulative distance matrix c nm arrive c 11 The minimum path.

7. A Lamb wave temperature compensation method as claimed in claim 5, characterized in that: Any variable in the nonlinear mapping matrix represents the matching of the reference signal and the signal to be matched, that is, the first variable in the signal to be matched y jk The element is assigned as the first i k 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.

8. A Lamb wave temperature compensation system, characterized in that: include: A calculation module is configured to: collect Lamb wave signals at different temperatures as a reference signal set, and calculate a nonlinear correlation coefficient between the waveguide signal to be compensated and each Lamb wave signal in the reference signal set; A sorting module is configured to: sort the calculated nonlinear correlation coefficients from large to small, take the temperatures corresponding to the top two nonlinear correlation coefficients as the endpoint values ​​of the optimal reference temperature interval according to the sorting result, and calculate the temperature estimate of the waveguide signal to be compensated; An optimal matching path module is configured to: determine an optimal matching path according to a positional relationship between the temperature estimation value and an endpoint value of the optimal reference temperature interval in combination with a time domain bending algorithm; A temperature compensation module is configured to perform temperature compensation on the waveguide signal to be compensated based on the optimal matching path.

9. An electronic device, characterized in that: The method comprises a memory and a processor and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method according to any one of claims 1 to 7 is completed.

10. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the method described in any one of claims 1 to 7.

Images