Parameter identification and real-time calibration method of pulsed eddy current receiving system based on underdamped dynamic response

Abstract

This invention relates to a method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response, belonging to the field of pulsed eddy current technology. In this invention, during coil calibration, the state switching switch S is switched to terminal 1, and the damping resistor R... b A state-switching resistor R1 is connected in series as a matching resistor to form an underdamped state. Simultaneously, a linearly varying excitation signal is applied to the receiving coil, generating a step signal ε(t) in the receiving coil. The signals at both ends of the coil are collected, and the peak time, overshoot, and steady-state value of the first system response are extracted to calculate the natural frequency and damping ratio. Similarly, the steady-state value of the second system response is extracted, and the equivalent resistance R0 of the receiving coil is calculated. The mapping relationship between the natural frequency, damping ratio, and the inductance L and distributed capacitance C of the receiving coil is obtained. Based on the parameter identification method, the bilinear equations are alternately optimized, and an objective function based on the bilinear equations is set to identify the parameters of L and C.

Description

Technical Field

[0001] This invention belongs to the field of pulsed eddy current technology and relates to a method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response. Background Technology

[0002] The pulsed eddy current receives the secondary magnetic field generated by the eddy current of the object being detected through a receiving coil. This secondary magnetic field is converted into an induced voltage by the coil, a lossless process. However, the attenuation of the induced voltage after passing through the coil and the acquisition system is affected by the transient process of the receiving coil, resulting in an attenuation pattern that deviates from the theoretical curve. To eliminate the influence of the coil transient process on the measurement signal and improve the accuracy of the magnetic field detection signal, the coil parameters are typically measured to obtain its transfer function. The induced voltage signal is then eliminated by deconvolution to recover the induced electromotive force. During the inverse operation, the accuracy of the coil parameters determines the accuracy of the results and the accuracy of the signal inversion imaging. After the initial coil measurement, the coil parameters change due to factors such as operating time and environment, leading to deviations in the calibration of the received signal from the actual results. However, since the receiving system is generally an integrated package design, it is difficult to measure the coil parameters directly from the receiving coil port.

[0003] To accurately measure the secondary field response using the distorted output signal of the receiving coil, a mapping between the coil's induced electromotive force (EMF) and the output signal must be established. This process is called coil sensor calibration. A common calibration method for coil sensors involves establishing a controllable calibration magnetic field in space and solving for the coil's calibration parameters by analyzing the relationship between the coil's induced EMF ε(t) and its output signal u(t). To analyze the characteristics of the input and output signals, a sinusoidal signal is typically used as the calibration signal. Several frequency values ​​are selected within the investigated frequency range, and the amplitude and phase angle of the input and steady-state output signals are measured at each calibration frequency. The transfer function of the coil under test is obtained by fitting the experimental data; this is called the frequency response method. However, environmental media or structural deformation can have a significant impact on the calibration parameters, making the calibration of transient electromagnetic receiving systems not a one-time process.

[0004] The frequency response test method is a classic calibration method for coil sensors. It obtains the induced electromotive force ε(t) and its output signal u(t) of the coil by establishing a controllable calibration magnetic field in space, and obtains the calibration file of the coil under test by fitting the experimental data. In the frequency response method, the induced electromotive force ε(t) of the coil under test needs to be solved according to Faraday's law of electromagnetic induction. To ensure the controllability of ε(t), this method not only requires a high-precision signal generator, but also must ensure the uniformity of the calibration magnetic field, which places high demands on the field source. The equipment used to generate a uniform magnetic field must be designed according to the size of the coil under test, resulting in poor versatility and making it impossible to calibrate the device on-site.

[0005] In summary, the parameters of the pulsed eddy current receiving coil may change due to long-term operation and the operating environment, which in turn leads to signal calibration deviation. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response includes the following steps:

[0009] S1: During normal operation, connect the state switching switch S to terminal 0, and set the damping resistor R... b Connected across the receiving coil as a matching resistor, it is used to keep the pulse eddy current receiving system in a critically damped state or a slightly overdamped state.

[0010] S2: When calibrating the coil, switch the state change switch S from terminal 0 to terminal 1, and set the damping resistor R... b The state switching resistor R1 is connected in series as a matching resistor to form an underdamped state; at the same time, a linearly changing excitation signal is applied to the receiving coil to generate a step signal ε(t) in the receiving coil, and the signals at both ends of the coil are collected to extract the peak time, overshoot and the steady-state value of the first system response, so as to calculate the natural frequency and damping ratio.

[0011] Switch the state toggle switch S to terminal 2, and set the damping resistor R... b The state switching resistor R2 is connected in series as a matching resistor to form an underdamped state; at the same time, a linearly changing excitation signal is applied to the receiving coil to generate a step signal ε(t) in the receiving coil, and the signal at both ends of the coil is collected to extract the steady-state value of the second system response.

[0012] S3: Calculate the equivalent resistance R0 of the receiving coil based on the steady-state values ​​of the first and second system responses;

[0013] S4: Given that the natural frequency, damping ratio, and R0 are all known, obtain the mapping relationship between the natural frequency, damping ratio, and the inductance L and distributed capacitance C of the receiving coil.

[0014] S5: Based on the parameter identification method, the bilinear equations are alternately optimized, and the objective function based on the bilinear equations is set to identify the parameters of the inductance L and distributed capacitance C of the receiving coil.

[0015] Furthermore, the damping resistor R b The formula for calculating the matching resistor during normal operation is as follows:

[0016]

[0017] Where R0, L, and C are the equivalent resistance, inductance, and distributed capacitance of the receiving coil, respectively.

[0018] Furthermore, the specific values ​​of peak time, overshoot, and steady-state system response can be extracted from the signals collected at both ends of the coil in step S2.

[0019] The peak time is the time required for the system response to reach its first maximum value, and is related to the damping ratio ζ1 and the natural frequency ω when the state switching switch S is switched to terminal 1. n1 Related:

[0020]

[0021] The overshoot is the maximum percentage of the step response exceeding the steady-state value, and its magnitude is related to the damping ratio ζ1 when the state switching switch S is switched to terminal 1:

[0022]

[0023] After acquiring the specific values ​​of overshoot and peak time, the damping ratio ζ1 and natural frequency ω are calculated using the above formula. n1 The relationship between the steady-state value of the system response and the equivalent resistance and matching resistance of the receiving coil is as follows:

[0024]

[0025] Furthermore, in step S3, based on the first system response steady-state value y collected in step S2... s1 The steady-state value of the second system response y s2 Calculate the equivalent resistance R0 of the receiving coil:

[0026] R bn =R b +R n n = 1, 2

[0027]

[0028] Furthermore, in step S4, given the natural frequency ω... n1 Damping ratios ζ1, R0, R1, and R b In the case of specific values, according to ω n1 The expression for ζ1:

[0029]

[0030] It can be seen that ω n1 ζ1 is only related to the inductance L and distributed capacitance C of the receiving coil, thus establishing a mapping relationship between the natural frequency, damping ratio and the inductance L and distributed capacitance C of the receiving coil.

[0031] Furthermore, step S5 specifically includes the following steps:

[0032] Since the mapping relationship between the natural frequency, damping ratio, and the inductance L and distributed capacitance C of the receiving coil is a double nonlinear equation, direct solution is difficult and has large errors. Therefore, the parameter identification method is used to solve the inductance and capacitance parameters of the receiving coil.

[0033] First, when designing the receiving system, the parameters of the receiving coil are measured, and the measured values ​​are set as the initial values ​​of the unknowns L and C.

[0034] Subsequently, the unknowns are updated alternately, and the double nonlinear equations are set up as follows:

[0035]

[0036] With C fixed, solve for L: In the first iteration, using f1=(L,C)=0 and f2=(L,C)=0, use Newton's method to solve for the new value of L;

[0037] With L fixed, solve for C: In the next iteration, using f1=(L,C)=0, f2=(L,C=0, we can use Newton's method to solve for the value of C;

[0038] Continue to update L and C alternately until the convergence criterion is met;

[0039] During each alternating update process, the residual changes are monitored to determine whether the optimization has reached stable convergence.

[0040]

[0041] By limiting the number of iterations and adjusting the solution accuracy of L and C through the error requirement ε, the parameter identification of the receiving coil inductance and distributed capacitance can be achieved.

[0042] The beneficial effects of this invention are as follows: By establishing a dual nonlinear identification equation, this invention can improve the accuracy of system identification, enhance robustness to model errors, and fully utilize the advantages of nonlinear optimization, thereby making parameter identification more reliable, based on the online identification and real-time calibration of the pulsed eddy current receiving system. Furthermore, compared to the traditional frequency response method, it does not require the establishment of a controllable calibration magnetic field, and has advantages such as ease of operation and wide applicability.

[0043] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. Attached Figure Description

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0045] Figure 1 This is a schematic diagram illustrating the switching of the receiving coil state and signal acquisition.

[0046] Figure 2 For the characteristic analysis of the second-order system, (a) is the unit step response of the second-order system with different damping ratios, (b) is the step response and characteristic parameters under underdamping, and (c) is the curve of the relationship between matching resistance and damping ratio.

[0047] Figure 3 Create a schematic diagram for parameter mapping;

[0048] Figure 4 A schematic diagram of the entire parameter identification process. Detailed Implementation

[0049] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0050] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0051] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0052] The schematic diagram of the receiving coil state switching and signal acquisition designed in this invention is shown below. Figure 1 As shown, R b R1 is the damping matching resistor for the receiving coil, S is the state switching switch, R1 is the state switching resistor, ε(t) is the step signal, V(t) is the induced electromotive force received by the receiving coil, and U(t) is the induced electromotive force measured by the acquisition module.

[0053] During normal operation, the state switching switch S is at position 0. The system's transfer function, damping ratio, and natural frequency are shown below:

[0054] Transfer function:

[0055]

[0056] Natural frequency ω n :

[0057]

[0058] Damping ratio ζ:

[0059]

[0060] Where R0, L, and C are the equivalent resistance, inductance, and distributed capacitance of the receiving coil, and s is the complex variable obtained after the Laplace transform. To ensure that the sensor output signal has minimal distortion and achieves a high-quality output response and a relatively flat frequency response, a matching resistor can be connected across the coil to bring the system to a critically damped state. However, in practical applications, the matching resistor is usually increased appropriately to allow the system to operate in a slightly overdamped state, preventing oscillations caused by underdamped conditions due to uncertainties. The formula for calculating the matching resistor is shown below:

[0061]

[0062] When calibrating the coil, the switch is switched from terminal 0 to terminal 1. At this time, the damping matching resistor R... b A state-switching resistor R1 is connected in series with the receiving coil, and a linearly varying excitation signal is applied to the receiving coil. A step signal ε(t) is generated in the receiving coil, and the acquisition module acquires the signal across the coil. The system transfer function at this time is:

[0063]

[0064] R b1 =R b +R1

[0065] From the transfer function, we can see that the natural frequency ω of the system is... n1 The expression for the damping ratio ζ1 remains unchanged, but because the damping resistor is connected in series with the state switching resistor, the matching resistance of the system increases, and the system changes from the original critically damped / slightly overdamped state to an underdamped state.

[0066] The unit step response of a second-order system with different damping ratios is as follows: Figure 2 As shown in (a), when the system is in an underdamped state, it will oscillate, and the amplitude of the oscillation will increase as the damping ratio decreases. The response signal waveform and characteristic parameters under underdamped oscillation are as follows. Figure 2 As shown in (b), when the system is in an underdamped oscillatory state, the system's step response is oscillatory, and the time to first reach the peak value is called the peak time. The percentage of the peak value exceeding the steady-state value corresponds to the overshoot. The relationship between the system's damping ratio and the matching resistor is as follows: Figure 2 As shown in (c), increasing the matching resistor value will reduce the damping ratio of the system. Therefore, by controlling the series state switching resistor by switching, the system can transition from critical damping to underdamped state.

[0067] This invention uses switch S for control. During system calibration, the state switching resistor R1 and the damping resistor R are connected. b The series connection puts the system in an underdamped state, and the peak time, overshoot, and steady-state value of the system can be obtained from the signal at both ends of the coil.

[0068] Peak time is the time required for the system response to reach its first maximum value, typically related to the damping ratio ζ1 and the natural frequency ω. n1 Related:

[0069]

[0070] Overshoot is the maximum percentage by which a step response exceeds its steady-state value. For a second-order system, its magnitude is closely related to the damping ratio ζ.

[0071]

[0072] System steady-state value:

[0073]

[0074] y s The steady-state value of the system response is given by the above equation. It can be seen that the steady-state value of the system depends only on the matching resistor and the coil parameter R0. Therefore, the steady-state value can be determined by switching R1 and R2 with the damping resistor R0 using the state switching switch S. b The R0 parameter can be obtained by connecting the phases in series to adjust the size of the matching resistor.

[0075] R bn =R b +R n n = 1, 2

[0076]

[0077] The two characteristic parameters are only related to the natural frequency and damping ratio, and are independent of the parameter to be identified. Given the matching resistance and natural frequency ω... n Given a specific value for the damping ratio ζ, the natural frequency ω can be established. n The mapping relationship between the damping ratio ζ and the parameters to be identified, L and C.

[0078] The corresponding parameter mapping establishment diagram is as follows: Figure 3 As shown, after acquiring the specific values ​​of overshoot and peak time, the overshoot and peak time are first compared with the damping ratio ζ1 and the natural frequency ω. n1 The relationship between damping ratio ζ1 and natural frequency ω is used to calculate the damping ratio ζ1 and natural frequency ω. n1 Specific values:

[0079]

[0080] Then by:

[0081]

[0082] Given the specific values ​​of the equivalent resistance and matching resistance of the receiving coil, the damping ratio ζ1 and the natural frequency ω n1 It is only related to L and C, thus establishing the natural frequency ω. n1 The mapping relationship between damping ratio ζ1 and the parameters to be identified, L and C.

[0083] After establishing the natural frequency ω n1After establishing the bilinear mapping relationship between the damping ratio ζ1 and the parameters to be identified, L0 and C0, the bilinear equations are alternately optimized based on the parameter identification method. An objective function based on the bilinear equations is then set to identify the parameters. Finally, the accuracy of the identification results is evaluated through the system response to obtain the accurate results of L and C after the changes, thus realizing the online identification and real-time calibration technology for the pulsed eddy current receiving system. The corresponding parameter identification flowchart is as follows: Figure 4 As shown.

[0084] Specifically, in obtaining the natural frequency ω n1 Based on the mapping relationship between the damping ratio ζ1 and the parameters to be identified, L and C, since the equation is a double nonlinear equation, direct solution is difficult and has a large error. Therefore, the parameter identification method is used to solve the inductance and capacitance parameters of the receiving coil.

[0085] First, when designing the receiving system, the parameters of the receiving coil are measured. Although the parameters of the receiving coil may deviate during operation, the error is small. Therefore, the measured values ​​are set as the initial values ​​of the unknowns L and C.

[0086] Subsequently, the unknowns are updated alternately. The double nonlinear equations are then expressed as:

[0087]

[0088] With C fixed, solve for L: In the first iteration, using f1=(L,C)=0 and f2=(L,C)=0, use Newton's method to solve for the new value of L.

[0089] With L fixed, solve for C: In the next iteration, using f1=(L,C)=0 and f2=(L,C)=0, Newton's method is used to solve for the value of C.

[0090] Continue to update L and C alternately until the convergence criterion is met.

[0091] During each alternating update process, the changes in residuals are monitored to determine whether the optimization has reached stable convergence.

[0092]

[0093] By limiting the number of iterations and adjusting the solution accuracy of L and C through the error requirement ε, the parameter identification of the receiving coil inductance and distributed capacitance can be achieved.

[0094] By establishing a dual nonlinear identification equation, the accuracy of system identification can be improved, robustness to model errors can be enhanced, and the advantages of nonlinear optimization can be fully utilized to achieve online identification and real-time calibration of the pulsed eddy current receiving system, thus making parameter identification more reliable. Furthermore, compared to the traditional frequency response method, it does not require the establishment of a controllable calibration magnetic field, and has advantages such as ease of operation and wide applicability.

[0095] In the above embodiments, the reference to "this embodiment" in the specification indicates that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple appearances of "this embodiment" do not necessarily refer to the same embodiment.

[0096] In the above embodiments, although the invention has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory structures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed. The embodiments of the invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims.

[0097] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the methods in this embodiment.

[0098] This embodiment also provides an electronic terminal, including: a processor and a memory;

[0099] The memory is used to store computer programs, and the processor is used to execute the computer programs stored in the memory to cause the terminal to perform any of the methods in this embodiment.

[0100] As will be understood by those skilled in the art, the computer-readable storage medium described in this embodiment allows for the implementation of all or part of the steps in the above method embodiments by computer program-related hardware. The aforementioned computer program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0101] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver, and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication between them. The memory is used to store computer programs, the communication interface is used to perform communication, and the processor and the transceiver are used to run the computer programs, so that the electronic terminal performs the steps of the above method.

[0102] In this embodiment, the memory may include random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage device.

[0103] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0104] This invention can be used in a wide range of general-purpose or special-purpose computing system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0105] This invention can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This invention can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response, characterized in that: Includes the following steps: S1: During normal operation, connect the state switching switch S to terminal 0, and set the damping resistor... R b Connected across the receiving coil as a matching resistor, it is used to keep the pulsed eddy current receiving system in a critically damped or slightly overdamped state; the damping resistor R b The formula for calculating the matching resistor during normal operation is as follows: in, R 0, L , C These are the equivalent resistance, inductance, and distributed capacitance of the receiving coil, respectively. S2: When calibrating the coil, switch the state change switch S from terminal 0 to terminal 1, and set the damping resistor... R b With state switching resistor R A series resistor is used as a matching resistor to create an underdamped state; simultaneously, a linearly varying excitation signal is applied to the receiving coil, generating a step signal in the receiving coil. ε ( t The system collects signals from both ends of the coil, extracts the peak time, overshoot, and steady-state value of the first system response, and then calculates the natural frequency and damping ratio. Switch the state toggle switch S to terminal 2, and set the damping resistor... R b With state switching resistor R Two resistors are connected in series as matching resistors to create an underdamped state; simultaneously, a linearly varying excitation signal is applied to the receiving coil, generating a step signal in the receiving coil. ε ( t The system collects signals from both ends of the coil and extracts the steady-state value of the second system response. S3: Calculate the equivalent resistance of the receiving coil based on the steady-state values ​​of the first and second system responses. R 0; S4: At natural frequency, damping ratio and R Given that all zeros are known, obtain the natural frequency, damping ratio, and inductance of the receiving coil. L Distributed capacitance C The mapping relationship between them; S5: Alternating optimization of the bilinear equations is performed based on the parameter identification method, and an objective function based on the bilinear equations is set for the inductance of the receiving coil. L Distributed capacitance C Perform parameter identification; step S5 specifically includes the following steps: First, when designing the receiving system, the parameters of the receiving coil are measured, and the measured values ​​are set as the initial values ​​of the unknowns L and C. Subsequently, the unknowns are updated alternately, and the double nonlinear equations are set up as follows: in ω n1 For natural frequency, ζ 1 represents the damping ratio; With C fixed, solve for L: In the first iteration, using f 1=(L,C)=0, f 2=(L,C)=0, and the new value of L is obtained by using Newton's method; With L fixed, solve for C: In the following iterations, using f 1=(L,C)=0, f 2=(L,C)=0, use Newton's method to solve for the value of C; Continue to update L and C alternately until the convergence criterion is met; During each alternating update process, the residual changes are monitored to determine whether the optimization has reached stable convergence. Error requirements ε This limits the number of iterations and adjusts the solution accuracy of L and C, thereby enabling parameter identification of the receiving coil inductance and distributed capacitance.

2. The method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response as described in claim 1, characterized in that: The specific values ​​of peak time, overshoot, and steady-state system response can be extracted from the signals collected at both ends of the coil in step S2. The peak time is the time required for the system response to reach its first maximum value, compared to the damping ratio when the state switching switch S is switched to terminal 1. ζ 1 and natural frequency ω n1 Related: The overshoot is the maximum percentage of the step response exceeding the steady-state value, and its magnitude is related to the damping ratio when the state switching switch S is switched to terminal 1. ζ 1 Related: After acquiring the specific values ​​of overshoot and peak time, the damping ratio is calculated using the above formula. ζ 1 and natural frequency ω n1 ; The relationship between the steady-state value of the system response and the equivalent resistance and matching resistance of the receiving coil is as follows: 。 3. The method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response according to claim 2, characterized in that: In step S3, based on the first system response steady-state value collected in step S2... y s1 Second system response steady state value y s2 Calculate the equivalent resistance of the receiving coil. R 0: 。 4. The method for parameter identification and real-time calibration of a pulsed eddy current receiving system based on underdamped dynamic response according to claim 3, characterized in that: In step S4, given the natural frequency ω n1 Damping ratio ζ 1. R 0、 R 1 and R b In the case of specific values, according to ω n1 , ζ The expression for 1: It can be seen that, ω n1 , ζ 1 Only the inductance of the receiving coil L Distributed capacitance C This establishes the relationship between the natural frequency, damping ratio, and inductance of the receiving coil. L Distributed capacitance C The mapping relationship between them.

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