A method for measuring the thickness of a metal component based on eddy current detection

Abstract

The application provides a metal component thickness measurement method based on eddy current detection, comprising: building an eddy current sensor with coaxial excitation and two receiving coils, forming two pairs of excitation-receiving coil units with different lift-off distances, and measuring the eddy current response signal of the metal component through a sweep frequency eddy current mode; calculating the mean value of the response signal, and obtaining a differential mutual inductance response curve by subtracting the mean value; analyzing the frequency and mutual inductance value corresponding to the intersection point of the curve; establishing an eddy current response analytical theory model, setting the electromagnetic parameters of the metal component and the geometric parameters of the sensor; inputting the frequency and mutual inductance value of the intersection point into the analytical model, converting the thickness measurement problem of the metal component into a least square optimization problem, using an improved Newton iteration algorithm to invert the thickness until the convergence condition is met, and finally outputting the thickness measurement result of the metal component. The method can realize accurate measurement of the thickness of the metal component and is not affected by the fluctuation change of the lift-off distance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic eddy current for non-contact dimensional metrology, and in particular to a metal component thickness measurement method based on eddy current detection. BACKGROUND

[0002] Metal components, such as the bases and supports of power equipment, provide stable support for other equipment in the power system. These components usually have high strength and rigidity, and can withstand the weight of the equipment itself and various forces and vibrations during operation, ensuring the stability and safety of the entire power system. When the components are thinned due to corrosion, etc., the cross-sectional area decreases, resulting in a decrease in carrying capacity. In the power system, this can make the components more prone to deformation or damage when subjected to normal or abnormal loads. In addition, for metal components that need to withstand complex loads such as bending moment and shear force, the thinning of the thickness will further reduce their stability. This can cause the components to be more prone to instability when subjected to external forces, affecting the overall stability of the power system. Therefore, it is very important to detect the thickness of metal components.

[0003] Eddy current detection technology has the characteristic of non-contact, and can measure the thickness without damaging the surface of the metal component. However, in actual detection process, if the lift-off distance between the eddy current detection probe and the surface of the measured metal component fluctuates, the strength of the eddy current signal will also fluctuate accordingly, and this fluctuation will affect the accuracy and stability of the eddy current detection results. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art to some extent.

[0005] To this end, the first object of the present application is to provide a metal component thickness measurement method based on eddy current detection.

[0006] The second object of the present application is to provide a metal component thickness measurement device based on eddy current detection.

[0007] The third object of the present application is to provide an electronic device.

[0008] The fourth object of the present application is to provide a computer-readable storage medium.

[0009] The fifth object of the present application is to provide a computer program product.

[0010] To achieve the above objects, the first aspect of the present application provides a metal component thickness measurement method based on eddy current detection, comprising:

[0011] S1, build a eddy current sensor composed of coaxial one excitation and two receiving coils, wherein the middle coil is the excitation coil, the bottom and end coils are receiving coils, and two pairs of excitation-receiving coil units with different lift-off distances are formed;

[0012] S2, using the eddy current sensor built, detecting the metal member in the sweep frequency eddy current mode, and obtaining the eddy current response signals M1(ω) and M2(ω) caused by the metal member;

[0013] S3, calculating the mean values m1 and m2 of the two groups of eddy current response signals respectively, and obtaining two differential mutual inductance response curves by subtracting the mean values from the original sweep frequency signals, and calculating the frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two differential mutual inductance response curves;

[0014] S4, establishing an eddy current response analytical theory model, and setting the electromagnetic parameters of the metal member and the geometric parameters of the eddy current sensor;

[0015] S5, inputting the frequency f c and the mutual inductance value M0 of the intersection point into the eddy current response analytical theory model, converting the thickness measurement problem of the metal member into a least square optimization problem, and solving it using an improved Newton iteration algorithm;

[0016] Repeating step S5 until the difference between the results of adjacent two iterations is less than a preset threshold or the maximum iteration number is reached, and finally outputting the thickness measurement result of the metal member.

[0017] Optionally, the eddy current sensor is designed as a coaxial one excitation and two receiving coil structure, wherein:

[0018] The sizes of the three coils are the same;

[0019] The middle coil is the excitation coil, and the bottom and end coils are the receiving coils, which is equivalent to constructing two pairs of mutual inductance eddy current sensors with different lift-off distances;

[0020] The lift-off distance of the first pair of excitation-receiving coils is l0, and the lift-off distance of the second pair of excitation-receiving coils is l0+g+h.

[0021] Optionally, the calculation of the mean values m1 and m2 of the two groups of eddy current response signals, and the obtaining of the two differential mutual inductance response curves by subtracting the mean values from the original sweep frequency signals, and the calculation of the frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two differential mutual inductance response curves, comprises:

[0022] Calculating the mean values of the eddy current response signals M1(ω) and M2(ω), and recording them as m1 and m2 respectively;

[0023] The eddy current response signals M1(ω) and M2(ω) are subtracted from the mean values ​​m1 and m2, respectively, to obtain two differential mutual inductance response curves M1(ω)-m1 and M2(ω)-m2.

[0024] Plot the differential mutual inductance response curves M1(ω)-m1 and M2(ω)-m2, find the intersection point where the mutual inductance values ​​of the two curves are equal, and calculate the frequency f corresponding to the intersection point of the two differential mutual inductance response curves. c Mutual inductance value M0.

[0025] Optionally, in the established analytical theoretical model of eddy current response, the electromagnetic parameters of the metal component include conductivity σ, and the geometric parameters of the eddy current sensor include: the inner diameter r1 and outer diameter r2 of the coil, as well as the height h and spacing g of the coil.

[0026] Optionally, the expression for the analytical theoretical model of the eddy current response is:

[0027]

[0028] In the formula:

[0029]

[0030] In the formula, M(ω) is the mutual inductance value of the eddy current response at angular frequency ω; K is the signal amplitude coefficient of the sensor, where N is the number of coil turns and μ0 is the vacuum permeability; P(α) is a function of the coil geometric parameters, where J1(t) is the first-order Bessel function and t is the integration variable; α is the integration variable, representing the wave number; φ(α) is a function related to the electromagnetic properties and thickness of the metal component; α1 is the complex wave number and j is the imaginary unit; d is the thickness of the metal component.

[0031] Optionally, the frequency f of the intersection point c The mutual inductance value M0 is input into the analytical theoretical model of the eddy current response, transforming the thickness measurement problem of the metal component into a least-squares optimization problem, which is then solved using an improved Newton iterative algorithm, including:

[0032] The frequency f at the intersection of the two differential mutual inductance response curves c The mutual inductance value M0 is input into the analytical theoretical model of the eddy current response;

[0033] The problem of measuring the thickness of the metal component is transformed into a least squares problem, and the objective function F(d) is defined as:

[0034]

[0035] In the formula, M(ω) c d) is the cross-point angular frequency ω calculated based on the analytical theoretical model of the eddy current response.c The differential mutual inductance value corresponding to the thickness d;

[0036] The Jacobian matrix J of the Newton iteration algorithm is calculated by using the difference quotient method d , and the expression is:

[0037]

[0038] In the formula, Δd is the thickness step;

[0039] The thickness value d is updated according to the following iteration formula:

[0040]

[0041] In the formula, d ′ is the thickness value of the metal member after updating, is the inverse of the Jacobian matrix, used to correct the thickness value.

[0042] To achieve the above purpose, the second aspect embodiment of the present application proposes a metal member thickness measurement device based on eddy current detection, comprising:

[0043] A sensor building module is used to build an eddy current sensor composed of coaxial excitation and two receiving coils, wherein the middle coil is the excitation coil, and the bottom and end coils are the receiving coils, forming two pairs of excitation-receiving coil units with different lift-off distances.

[0044] A detection module is used to detect the metal member in the frequency sweeping eddy current mode by using the built eddy current sensor, and obtain the eddy current response signals M1(ω) and M2(ω) caused by the metal member.

[0045] A calculation module is used to calculate the mean values m1 and m2 of the two groups of eddy current response signals respectively, and to obtain two differential mutual inductance response curves by subtracting the mean values from the original frequency sweeping signals, and to calculate the frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two differential mutual inductance response curves.

[0046] A model building module is used to build an eddy current response analytical theory model, and to set the electromagnetic parameters of the metal member and the geometric parameters of the eddy current sensor.

[0047] A solving module is used to input the frequency f c and the mutual inductance value M0 of the intersection point into the eddy current response analytical theory model, to convert the thickness measurement problem of the metal member into a least squares optimization problem, and to solve it using an improved Newton iteration algorithm.

[0048] A circulation module is configured to repeatedly execute the inputting and solving process until a difference between results of two adjacent iterations is less than a preset threshold or a maximum iteration number is reached, and finally output a thickness measurement result of the metal component.

[0049] To achieve the above object, the third aspect of the present application provides an electronic device, comprising: a processor, and a memory connected with the processor in communication;

[0050] The memory stores computer execution instructions.

[0051] The processor executes the computer execution instructions stored in the memory to implement the method according to any one of the first aspect.

[0052] To achieve the above object, the fourth aspect of the present application provides a computer readable storage medium, wherein the computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by a processor to implement the method according to any one of the first aspect.

[0053] To achieve the above object, the fifth aspect of the present application provides a computer program product, wherein the computer program is executed by a processor to implement the method according to any one of the first aspect.

[0054] The technical scheme provided by the embodiments of the present application at least brings the following beneficial effects:

[0055] The method can realize accurate measurement of the thickness of the metal component and is not affected by the fluctuation of the lift-off distance.

[0056] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0057] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the accompanying drawings.

[0058] Figure 1 A flowchart of a metal component thickness measurement method based on eddy current detection provided by the embodiments of the present application;

[0059] Figure 2 A schematic diagram of a coaxial eddy current sensor composed of one excitation coil and two receiving coils provided by the embodiments of the present application;

[0060] Figure 3 A response signal waveform diagram of a coaxial eddy current sensor under different lift-off distances provided by the embodiments of the present application;

[0061] Figure 4A differential response signal waveform diagram of the coaxial eddy current sensor at different lift-off distances provided by the embodiment of the present application is shown in the figure.

[0062] Figure 5 A structural schematic diagram of a metal member thickness measurement device based on eddy current detection provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0063] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0064] In view of the problems existing in the prior art, the embodiment of the present application provides a metal member thickness measurement method based on eddy current detection, Figure 1 A flowchart of a metal member thickness measurement method based on eddy current detection provided by the embodiment of the present application is shown in the figure. As shown in the figure, Figure 1 the method comprises the following steps:

[0065] S1, a coaxial eddy current sensor composed of one excitation coil and two receiving coils is built, wherein the middle coil is the excitation coil, the bottom and end coils are the receiving coils, and two pairs of excitation-receiving coil units with different lift-off distances are formed.

[0066] The embodiment of the present application adopts a coaxial eddy current sensor composed of one excitation coil and two receiving coils. As shown in the figure, Figure 2 the design structure of the sensor is that the middle coil is the excitation coil, the bottom and end coils are the receiving coils, the sizes of the three coils are the same, the axes are aligned, and the coaxial arrangement is maintained. The excitation coil is used to generate an eddy current field in the metal member, and the receiving coil is used to detect the response signal caused by the eddy current field in the metal member.

[0067] Through this design, the eddy current sensor forms two pairs of excitation-receiving coil units with different lift-off distances:

[0068] The first pair of coils: the excitation coil and the bottom receiving coil, the lift-off distance is l0;

[0069] The second pair of coils: the excitation coil and the end receiving coil, the lift-off distance is l0+g+h, wherein g represents the coil spacing, and h represents the coil height.

[0070] It can be understood that the two pairs of excitation-reception coil units can detect eddy current response signals of different depths due to the different lift-off distances, thereby improving the measurement accuracy and robustness. The two pairs of coils are equivalent to constructing two pairs of mutual inductance eddy current sensors with different lift-off distances, so that the design can better suppress the influence of lift-off distance fluctuation on the measurement results.

[0071] In addition, the parameters of the coils (such as the inner diameter, outer diameter, height, etc. of the coils) are optimized to ensure a balance between signal strength and analysis accuracy, thereby improving detection performance.

[0072] S2, using the eddy current sensor built, in the sweep frequency eddy current mode, detecting the metal component, and obtaining the eddy current response signals M1(ω) and M2(ω) caused by the metal component.

[0073] In the embodiment of the present application, the eddy current sensor built is used to detect the metal component in the sweep frequency eddy current mode, and the eddy current response signals M1(ω) and M2(ω) caused by the metal component are obtained. Specifically, the stacked array eddy current sensor is placed above the metal component to be detected, and a fixed distance between the sensor and the surface of the metal component is maintained. The excitation coil injects alternating current in a sweep frequency manner, and the excitation frequency range is set to 10Hz to 1MHz to cover the eddy current response from the surface to the deep layer.

[0074] It should be noted that the essence of the measurement is to detect the characteristic curve of the coil impedance change with frequency. By measuring the impedance change of the receiving coil at different frequencies, the eddy current response signals of the first pair and the second pair of excitation-reception coil units can be obtained respectively. These signals are shown in Figure 3 , which shows the typical frequency domain characteristics of the eddy current response signal, reflecting the electromagnetic response of the metal component at different frequencies.

[0075] This sweep frequency eddy current mode can cover the eddy current signals from the surface to the deep layer, effectively improving the accuracy and stability of the thickness measurement, and providing a high-quality data basis for subsequent signal processing and thickness inversion.

[0076] S3, respectively calculating the mean values m1 and m2 of the two groups of eddy current response signals, and obtaining two differential mutual inductance response curves by subtracting the mean values from the original sweep frequency signals, calculating the frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two differential mutual inductance response curves.

[0077] It should be noted that the response signals M1(ω) and M2(ω) measured by the eddy current sensor in the sweep frequency eddy current mode will be significantly affected by the change of the lift-off distance, mainly in the form of signal amplitude difference.

[0078] In the embodiments of the present application, the mean values m1 and m2 of the eddy current response signals M1(ω) and M2(ω) are calculated respectively, and the original sweep signal is processed to obtain two differential mutual inductance response curves, and then the characteristic frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two curves are analyzed.

[0079] First, the mean values m1 and m2 of the two groups of eddy current response signals in the entire sweep range are calculated.

[0080] Then, the eddy current response signals M1(ω) and M2(ω) are subtracted from their mean values m1 and m2 respectively to obtain two differential mutual inductance response curves M1(ω)-m1 and M2(ω)-m2. This differential processing can effectively remove the direct influence of the lift-off distance change on the signal amplitude and highlight the phase and frequency characteristics of the signal.

[0081] Next, the calculated differential mutual inductance response curves M1(ω)-m1 and M2(ω)-m2 are plotted in the same graph as shown in Figure 4 . The two curves reflect the differential response characteristics of the two pairs of coil units, showing obvious intersection characteristics.

[0082] Finally, the intersection point of the two differential mutual inductance response curves M1(ω)-m1 and M2(ω)-m2 is analyzed, and it is determined that the mutual inductance values of the two curves at the intersection point are equal, and the characteristic frequency f c (angular frequency ω c ) and the mutual inductance value M0 corresponding to the intersection point are calculated.

[0083] It can be understood that the characteristic frequency f c and the mutual inductance value M0 of the intersection point are key parameters for measuring the thickness of the metal member, and subsequent steps will use these parameters to perform inversion calculation of the thickness combined with the analytical theory model. The differential mutual inductance response curve (such as Figure 4 ) intuitively shows that the influence of the lift-off distance change on the signal amplitude is effectively suppressed, providing a reliable basis for subsequent data analysis.

[0084] S4, an eddy current response analytical theory model is established, and electromagnetic parameters of the metal member and geometric parameters of the eddy current sensor are set.

[0085] In the present application, in order to realize accurate measurement of the thickness of the metal member, an eddy current response analytical theory model is established to describe the relationship between the mutual inductance response of the excitation coil and the receiving coil under the sweep eddy current mode and the thickness and electromagnetic characteristics of the metal member.

[0086] Specifically, the eddy current response analytical theory model takes the electromagnetic characteristics of the metal member, the geometric parameters of the sensor, and the measurement frequency as inputs to describe the mutual inductance value change between the excitation coil and the receiving coil. The mathematical expression of the eddy current response analytical theory model is

[0087]

[0088] wherein:

[0089]

[0090] wherein, M(ω) is the eddy current response mutual inductance value at angular frequency ω; K is the signal amplitude coefficient of the sensor, wherein N is the number of turns of the coil, and μ0 is the vacuum permeability; P(α) is a function of the coil geometry parameter, wherein J1(t) is a first-order Bessel function, t is an integral variable; α is an integral variable, representing the wave number; φ(α) is a function related to the electromagnetic properties and thickness of the metal member; α1 is a complex wave number, and j is an imaginary unit; and d is the thickness of the metal member.

[0091] In the model, the electromagnetic properties of the metal member are represented by the conductivity σ. The conductivity directly affects the strength and distribution of the eddy current and is an important parameter for thickness measurement.

[0092] In addition, the design parameters of the eddy current sensor directly affect the mutual inductance response of excitation and reception, and the following geometry parameters need to be set in the analytical model: the inner diameter r1 and the outer diameter r2 of the coil: determine the size and coverage of the coil; the height h of the coil: affects the distribution of the magnetic field and the depth effect of the eddy current; the coil spacing g: adjusts the relative position of the two sets of receiving coils and affects the mutual inductance response of the lift-off distance.

[0093] In an embodiment, the metal material is an aluminum plate, and the conductivity is set to 3.8×10 7 S / m, the inner diameter and the outer diameter of the coil in the sensor are set to 3 mm and 7 mm respectively, the height of the coil is 1 mm, the spacing of the coil is 1 mm, and the number of turns of the coil is 100.

[0094] In addition, the model also needs to consider the lift-off distance of the two pairs of excitation-receiving coil units, and different lift-off distances can realize detection of the eddy current response of different depths of the metal member, thereby improving the sensitivity and anti-interference ability of the measurement. The present application does not make too many explanations.

[0095] By setting the above electromagnetic parameters and geometry parameters, the analytical theoretical model can accurately represent the electromagnetic response relationship between the eddy current sensor and the metal member, thereby providing a reliable theoretical basis for subsequent thickness inversion calculation.

[0096] S5, input the frequency f c and the mutual inductance value M0 of the intersection point into the eddy current response analytical theoretical model, convert the thickness measurement problem of the metal member into a least squares optimization problem, and use an improved Newton iteration algorithm to solve.

[0097] In the embodiment of the present application, first, the frequency fc and the mutual inductance value M0input into the eddy current response analytical model, combining the model expression M(ω c , d) to optimize the solution of the thickness d.

[0098] It can be understood that the measurement problem of the thickness is essentially to find the thickness d when the theoretical calculation value M(ω c , d) is closest to the actual measured value M0. For this purpose, the present application converts the thickness measurement problem of the metal member into a least squares optimization problem, and the objective function F(d) is defined as:

[0099]

[0100] In the formula, M(ω c , d) is the intersection point angular frequency ω c corresponding to the thickness d.

[0101] In order to solve the thickness d by using the Newton iteration algorithm, it is necessary to first calculate the Jacobian matrix J d of the analytical model. In order to realize the optimization solution, the difference quotient method is used to calculate the Jacobian matrix J d of the Newton iteration algorithm in the embodiments of the present application, and the expression is:

[0102]

[0103] In the formula, Δd is the thickness step. The difference quotient method obtains the approximate value of the Jacobian matrix by calculating the mutual inductance value difference at adjacent thickness points. This method is simple to calculate and can meet the real-time requirements of the present application in the thickness inversion process.

[0104] Therefore, according to the principle of the Newton iteration algorithm, the update formula of the thickness value d is:

[0105]

[0106] In the formula, d ′ is the thickness value of the metal member after updating, is the inverse of the Jacobian matrix, which is used to correct the thickness value.

[0107] It should be noted that the update process of the thickness value d is an iterative process of gradually approaching the true thickness, and the Jacobian matrix calculation and thickness value update need to be repeated multiple times until one of the following convergence conditions is met: the difference between the adjacent two iteration results is less than a preset threshold or the maximum iteration number is reached.

[0108] In a possible embodiment, when the difference between the inversion results of the adjacent two thicknesses is less than 1×10 -5 mm, or the maximum iteration number 100 is reached, the iteration is ended.

[0109] When the convergence condition is met, the output thickness value is the final thickness measurement result of the metal member.

[0110] It can be understood that the final output of the Newton iteration algorithm is the metal member thickness value obtained based on a least square optimization problem. The result has high accuracy and robustness under fluctuation of lift-off distance and can meet the actual application requirements. Through the above steps, the application realizes accurate inversion calculation of the thickness of the metal member, and the improvement of the Newton iteration algorithm further improves the efficiency and accuracy of the calculation.

[0111] In order to realize the above-mentioned embodiments, the application further provides a metal member thickness measurement device based on eddy current detection. Figure 5 A structural schematic diagram of a metal member thickness measurement device based on eddy current detection provided by an embodiment of the application is shown in FIG. 1. As shown in the figure, the device comprises: Figure 5

[0112] A sensor building module 100 is configured to build an eddy current sensor composed of coaxial excitation and reception coils, wherein the middle coil is an excitation coil, and the bottom and end coils are reception coils, forming two pairs of excitation-reception coil units with different lift-off distances.

[0113] A detection module 200 is configured to detect the metal member in a sweep frequency eddy current mode using the built eddy current sensor, and obtain eddy current response signals M1(ω) and M2(ω) caused by the metal member.

[0114] A calculation module 300 is configured to calculate the mean values m1 and m2 of the two groups of eddy current response signals respectively, and obtain two differential mutual inductance response curves by subtracting the mean values from the original sweep frequency signals, and calculate the frequency f c and the mutual inductance value M0 corresponding to the intersection point of the two differential mutual inductance response curves.

[0115] A model building module 400 is configured to build an eddy current response analytical theory model, and set electromagnetic parameters of the metal member and geometric parameters of the eddy current sensor.

[0116] A solving module 500 is configured to input the frequency f c and the mutual inductance value M0 of the intersection point into the eddy current response analytical theory model, convert the thickness measurement problem of the metal member into a least square optimization problem, and solve it using an improved Newton iteration algorithm.

[0117] A loop module 600 is configured to repeatedly execute the above input and solving process until the difference between the results of adjacent two iterations is less than a preset threshold or the maximum number of iterations is reached, and finally output the thickness measurement result of the metal member.

[0118] ​To achieve the above-mentioned embodiments, the present application further provides an electronic device, comprising: a processor, and a memory connected with the processor in communication; the memory stores computer execution instructions; the processor executes the computer execution instructions stored in the memory to realize the method provided by the foregoing embodiments.

[0119] To achieve the above-mentioned embodiments, the present application further provides a computer readable storage medium, wherein the computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by a processor to realize the method provided by the foregoing embodiments.

[0120] To achieve the above-mentioned embodiments, the present application further provides a computer program product, comprising a computer program, wherein the computer program is executed by a processor to realize the method provided by the foregoing embodiments.

[0121] The collection, storage, use, processing, transmission, provision and disclosure of user personal information involved in the present application comply with relevant laws and regulations and do not violate public order and good customs.

[0122] It should be noted that the personal information from the user should be collected for legal and reasonable purposes, and should not be shared or sold outside these legal uses. In addition, such collection / sharing should be carried out after the user's informed consent is received, including but not limited to informing the user to read the user agreement / user notice before the user uses the function, and signing the agreement / authorization including authorization of relevant user information. In addition, any necessary steps should be taken to protect and ensure access to such personal information data, and to ensure that other people with access to personal information data comply with their privacy policy and processes.

[0123] The present application is expected to provide embodiments in which the user can selectively prevent the use or access of personal information data. That is, the present disclosure is expected to provide hardware and / or software to prevent or block access to such personal information data. Once the personal information data is no longer needed, the risk is minimized by limiting data collection and deleting data. In addition, such personal information is de-identified, as applicable, to protect the privacy of the user.

[0124] In the foregoing detailed description, reference is made to descriptive terms such as "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" etc. for describing various embodiments of the application. These descriptive terms are used for the purpose of the description and are not meant to limit or restrict the scope of the application. The use of these terms does not imply that the application is comprised of at least the features described in the specific example. In addition, the description is not meant to imply that the described embodiments are the only manner in which the application can be practiced. Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Moreover, the described embodiments and features are not meant to be all inclusive but rather are meant to be exemplary only. Furthermore, those skilled in the art will recognize that the described embodiments and features can be combined with other embodiments and features in a suitable manner without departing from the scope of the application.

[0125] In addition, the terms "first", "second", etc. are used herein only to describe various embodiments and do not imply either a relative importance or an implicit indication that the described features are limited to a quantity of two or more. Thus, features defined with "first", "second" etc. can include at least one of the features implicitly or explicitly. In the description of the application, the meaning of "a plurality" is at least two, for example two, three, etc., unless otherwise expressly specified.

[0126] Any process or method descriptions or blocks in flow charts or otherwise described herein represent embodiments of the application that can be managed as one or more modules, segments, or portions of code that include one or more steps for implementing specific logic functions or steps, and the terms "module", "segment" or "portion" can be used in the description of this application to represent one or more such steps as performing a particular function or set of functions. The embodiments of the application should thus be understood to include a tangible medium that can be configured or arranged to record, store, or otherwise maintain a code that can be used to program a computer to perform a process or method as described herein. Thus, the embodiments of the application also should be understood to include a computer-readable medium that can have stored thereon code that, when included in or performed by a computer, can implement an application program or applet specified herein.

[0127] The logic and / or steps represented in flow diagrams or otherwise described herein, for example, can be considered as a sequence of instructions to implement logic functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device, such as a computer-based system, processor- containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this specification, a "computer-readable medium" can be any means that can contain, store, communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be a machine-readable storage device (e.g., magnetic, optical or other) a machine-readable storage diskette (e.g., floppy disk, optical disk, CD- ROM, etc.), a machine- readable storage card (e.g., PCMCIA card, etc.), a machine-readable storage tape (e.g., magnetic tape, optical tape, etc.), a machine-readable storage medium (e.g., RAM, ROM, etc.), a machine-readable signal (e.g., electrical, optical, etc.), a machine-readable medium (e.g., carrier wave, etc.) or any other suitable medium or means of embodying the program. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a RAM, a ROM, an EPROM, a FLASH memory card, an optical fiber, and a portable compact disc read-only memory (CD-ROM). Additionally, the computer-readable medium can be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, for example, via optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and stored in a computer memory.

[0128] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. As such, in some embodiments, the steps or methods can be implemented in hardware such as a special purpose computer, a programmed microprocessor or microcontroller, a microprocessor-based or a microcontroller-based application-specific integrated circuit, a peripheral integrated circuit element, a digital signal processor, a highly-parallelized architecture or other similar or well-known computing devices. In other embodiments, the steps or methods can be implemented in software that is stored in a memory and executed on a suitable instruction execution system. In other embodiments, the steps or methods can be implemented in a combination of both software and hardware.

[0129] Those of skill in the art would understand that information and signals can be represented using any of a variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0130] In addition, each of the function units in each embodiment of the present application can be integrated in one processing module, or each unit can be physically present separately, or two or more units can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software function module. When the integrated module is realized in the form of a software function module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0131] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

[0132] It should be understood that the various forms of flow shown above can be reordered, added or deleted steps. For example, each step described in the present application can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present application can be achieved, which is not limited herein.

[0133] The above detailed description does not constitute a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and replacements can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for measuring the thickness of metal components based on eddy current detection, characterized in that, Includes the following steps: S1. Construct an eddy current sensor consisting of a coaxial excitation coil and two receiving coils. The middle coil is the excitation coil, and the bottom and end coils are the receiving coils, forming two pairs of excitation-receiving coil units with different lift-off distances. The eddy current sensor is designed as a coaxial excitation coil with two receiving coils, wherein: the three coils are of the same size; the middle coil is the excitation coil, and the bottom and end coils are the receiving coils, equivalent to constructing two pairs of mutually inductive eddy current sensors with different lift-off distances; the lift-off distance of the first pair of excitation-receiving coils is... The lift-off distance of the second pair of excitation-receiver coils is In the established analytical theoretical model of eddy current response, the electromagnetic parameters of the metal component include conductivity. The geometric parameters of the eddy current sensor include: the inner diameter of the coil. and outer diameter and the height of the coil and coil spacing ; S2. Using the constructed eddy current sensor, the metal component is detected in swept-frequency eddy current mode to obtain the eddy current response signal caused by the metal component. and In the detection process, the eddy current sensor is placed above the metal component to be tested, maintaining a fixed distance between the sensor and the surface of the metal component. An alternating current is injected through the excitation coil in a frequency sweep manner. The range of the excitation frequency is set from 10Hz to 1MHz to cover the eddy current response from the surface to the deep layers. S3. Calculate the mean values ​​of the two sets of eddy current response signals respectively. and The original swept frequency signal is then subtracted from the mean to obtain two differential mutual inductance response curves. The frequency corresponding to the intersection point of the two differential mutual inductance response curves is then calculated. Mutual inductance value ; S4. Establish an analytical theoretical model of eddy current response, and set the electromagnetic parameters of the metal component and the geometric parameters of the eddy current sensor; S5, the frequency of the intersection point Mutual inductance value The analytical theoretical model of eddy current response is input, and the thickness measurement problem of the metal component is transformed into a least squares optimization problem, which is then solved using the improved Newton iterative algorithm. Repeat step S5 until the difference between two adjacent iterations is less than a preset threshold or the maximum number of iterations is reached, and finally output the thickness measurement result of the metal component; The expression for the analytical theoretical model of eddy current response is: In the formula: In the formula, Angular frequency The mutual inductance value of the eddy current response under the following conditions; is the signal amplitude coefficient of the sensor, where The number of coil turns. Permeability of free space; is a function of the geometric parameters of the coil, where It is a first-order Bessel function. For integration variables; Let be the integral variable, representing the wave number; It is a function related to the electromagnetic properties and thickness of the metal component; For complex wave number, The imaginary unit; The thickness of the metal component; The frequency of the intersection point Mutual inductance value Inputting the analytical theoretical model of the eddy current response, the thickness measurement problem of the metal component is transformed into a least-squares optimization problem, which is then solved using an improved Newton iterative algorithm, including: The frequency at the intersection of the two differential mutual inductance response curves Mutual inductance value Input the analytical theoretical model of the eddy current response; The problem of measuring the thickness of the metal component is transformed into a least squares problem, and the objective function is defined. for: In the formula, The cross-point angular frequency calculated based on the analytical theoretical model of the eddy current response. Below, thickness The corresponding differential mutual inductance values; Calculate the Jacobian matrix of Newton's iterative algorithm using the difference quotient method. The expression is: In the formula, This represents the thickness step size. The thickness value is updated according to the following iterative formula. : In the formula, To update the thickness value of the metal component, It is the inverse of the Jacobian matrix, used to correct the thickness value.

2. The method according to claim 1, characterized in that, The mean values ​​of the two sets of eddy current response signals are calculated respectively. and The original swept frequency signal is then subtracted from the mean to obtain two differential mutual inductance response curves. The frequency corresponding to the intersection point of the two differential mutual inductance response curves is then calculated. Mutual inductance value ,include: Calculate the eddy current response signal and The mean of each is denoted as . and ; eddy current response signal and respectively with the mean and By subtracting the two values, we obtain two differential mutual inductance response curves. and ; Plotting differential mutual inductance response curves and The intersection point where the mutual inductance values ​​of the two curves are equal is obtained, and the frequency corresponding to the intersection point of the two differential mutual inductance response curves is calculated. Mutual inductance value .

3. A metal component thickness measuring device based on eddy current detection according to the method of any one of claims 1-2, characterized in that, include: The sensor building module is used to build an eddy current sensor consisting of a coaxial excitation coil and two receiving coils. The middle coil is the excitation coil, and the bottom and end coils are the receiving coils, forming two pairs of excitation-receiver coil units with different lift-off distances. The detection module is used to detect the metal component using the assembled eddy current sensor in a swept-frequency eddy current mode, and to acquire the eddy current response signal caused by the metal component. and ; The calculation module is used to calculate the mean of the two sets of eddy current response signals respectively. and The original swept frequency signal is then subtracted from the mean to obtain two differential mutual inductance response curves. The frequency corresponding to the intersection point of the two differential mutual inductance response curves is then calculated. Mutual inductance value ; The model building module is used to build an analytical theoretical model of eddy current response and set the electromagnetic parameters of the metal component and the geometric parameters of the eddy current sensor. The solver module is used to calculate the frequency of the intersection points. Mutual inductance value The analytical theoretical model of eddy current response is input, and the thickness measurement problem of the metal component is transformed into a least squares optimization problem, which is then solved using the improved Newton iterative algorithm. The loop module is used to repeatedly execute the above input and solution process until the difference between two adjacent iterations is less than a preset threshold or the maximum number of iterations is reached, and finally outputs the thickness measurement result of the metal component.

4. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1-2.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-2.

6. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method of any one of claims 1-2.

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