Electromagnetic ultrasonic internal detection lift-off compensation method, system and equipment and storage medium

Abstract

The invention provides an electromagnetic ultrasonic internal detection lift-off compensation method, system and device and a storage medium. The method comprises the following steps: configuring a reference signal for electromagnetic ultrasonic internal detection; preprocessing a received signal acquired in the electromagnetic ultrasonic internal detection process by adopting a time domain average noise reduction method; based on the reference signal, determining the relative position of a characteristic signal in the received signal by adopting a cross-correlation method, and performing amplitude compensation on the characteristic signal in combination with a lift-off height experiment so as to determine gate information; based on the gate information, time information corresponding to the position of the characteristic signal is accurately obtained, and then the echo time difference of the linear corresponding position is determined through multiple times of echo fitting; and calculating the wall thickness value of the pipeline according to the echo time difference and the propagation sound velocity of the ultrasonic waves in the wall of the pipeline. According to the method, the adverse effect of lift-off change on measurement is effectively overcome, and the precision and robustness of pipeline wall thickness internal detection under complex working conditions are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of in-pipe detection, and in particular to an electromagnetic ultrasonic in-pipe detection lift-off compensation method, system, device and storage medium. BACKGROUND

[0002] Electromagnetic acoustic transducer (EMAT) technology uses electromagnetic induction principle to directly excite and receive ultrasonic waves in conductive materials, and has the advantages of non-contact, no need for coupling agent, and suitability for high-speed detection, and has been widely applied in in-pipe corrosion defect detection and thickness measurement.

[0003] However, in the actual in-pipe detection process, the distance between the probe and the inner wall of the measured pipe (i.e. the lift-off distance) is difficult to keep constant at all times. The existence of the lift-off effect will significantly affect the coupling efficiency of the ultrasonic signal, causing the amplitude of the echo signal to attenuate, and possibly causing phase shift and waveform distortion. When the lift-off distance is large, the echo signal may be overwhelmed by environmental noise, making it difficult to accurately identify the echo arrival time, thereby introducing significant thickness measurement errors. In addition, lift-off changes can also excite unnecessary waveforms (such as Lamb waves), further interfering with the extraction of effective signals.

[0004] Currently, although some research attempts to compensate through signal processing algorithms, most focus on a single approach, such as simple amplitude calibration or noise filtering, which is difficult to overcome the various adverse effects of the lift-off effect in a complex and variable in-pipe detection environment. Therefore, there is an urgent need in the art for a comprehensive lift-off compensation method that can simultaneously address signal attenuation, time difference fluctuations, and noise interference to improve the reliability and accuracy of electromagnetic ultrasonic in-pipe detection. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide an electromagnetic ultrasonic in-pipe detection lift-off compensation method, system, device and storage medium. The method effectively suppresses the effects of lift-off through an integrated signal processing and compensation process, thereby improving the accuracy of thickness measurement.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides an electromagnetic ultrasonic in-pipe detection lift-off compensation method, comprising the following steps:

[0008] configuring a reference signal for electromagnetic ultrasonic in-pipe detection;

[0009] using a time domain average noise reduction method to pre-process the received signal collected during electromagnetic ultrasonic in-pipe detection;

[0010] Based on the reference signal, a cross-correlation method is used to determine the relative position of the characteristic signal in the received signal, and the amplitude compensation of the characteristic signal is combined with the lift-off height experiment to determine the gate information;

[0011] Based on the gate information, the time information corresponding to the position of the characteristic signal is accurately obtained, and then the echo time difference of the linear corresponding position is determined through multiple echo fitting;

[0012] According to the echo time difference and the propagation speed of ultrasonic waves in the pipeline wall, the pipeline wall thickness value is calculated.

[0013] In an embodiment, the time domain average noise reduction method includes:

[0014] After digital-to-analog conversion of each channel data of the received signal, the data is stored in sequence according to the sampling point time;

[0015] At least N data points per second are stored for each channel;

[0016] The average value of at least the N data points is calculated under different time scales.

[0017] In an embodiment, the process of cross-correlation operation includes:

[0018] The preprocessed received signal is cross-correlated with the reference signal;

[0019] The operation process uses frequency domain fast Fourier transform;

[0020] The cross-correlation function is obtained by calculating the sliding inner product of the two signals, and the peak value of the cross-correlation function corresponds to the best alignment delay of the characteristic signal, so as to determine the relative position of the characteristic signal.

[0021] In an embodiment, the amplitude compensation method includes:

[0022] The signal attenuation curve under different lift-off heights is calibrated through experiments, and an amplitude library corresponding to different lift-off heights and ideal signal amplitudes is constructed;

[0023] According to the lift-off height in actual detection, the corresponding ideal signal amplitude is selected from the amplitude library to compensate the measured amplitude of the characteristic signal, and the compensation formula is:

[0024] A c =A f e ah ,

[0025] In the formula, A c is the signal amplitude under the measured lift-off environment, A f is the ideal signal amplitude calibrated by the lift-off experiment, and α is the attenuation coefficient.

[0026] In an embodiment, the multi-echo fitting process comprises:

[0027] Collecting multi-echo signals generated by the reflection of ultrasonic waves in the pipe wall, the multi-echo signals including primary echoes, secondary echoes and subsequent echoes until the energy is dissipated;

[0028] Determining the time difference of the multi-echo signals with the time information of the echo amplitude position, and obtaining the echo time difference of the linearly corresponding position by linear fitting.

[0029] In an embodiment, before determining the relative position of the characteristic signal, the method further comprises the step of pre-determining a set of received signals, specifically comprising:

[0030] Creating a blank received signal, the length of the blank received signal being the sum of the reference signal length and the maximum delay amount, and initializing a full zero array as the blank received signal;

[0031] Filling the amplitude-scaled reference signal into a specific position of the blank received signal to simulate the signal delay effect;

[0032] Calculating the reference signal power, generating a Gaussian white noise sequence corresponding to the power according to the signal-to-noise ratio, and adding the Gaussian white noise sequence to the blank received signal;

[0033] Adding an interference signal to the blank received signal to determine the pre-received signal.

[0034] In an embodiment, the formula for calculating the pipe wall thickness value is:

[0035]

[0036] In the formula, d is the pipe wall thickness, v is the propagation speed of ultrasonic waves in the pipe wall, t n is the echo time difference of the linearly corresponding position.

[0037] In a second aspect, the present application provides an electromagnetic ultrasonic internal detection lift-off compensation system, characterized in that the system comprises:

[0038] A configuration module for configuring a reference signal for electromagnetic ultrasonic internal detection;

[0039] A preprocessing module for pre-processing the received signals collected in the electromagnetic ultrasonic internal detection process by using a time domain average noise reduction method;

[0040] A compensation module for determining the relative position of a characteristic signal in the received signals based on the reference signal by using a cross-correlation method, and performing amplitude compensation on the characteristic signal in combination with a lift-off height experiment to determine gate information;

[0041] The acquisition module is configured to acquire time information corresponding to the characteristic signal position based on the gate information, and then determine an echo time difference of linear corresponding positions through multiple echo fitting;

[0042] The calculation module is configured to calculate a pipe wall thickness value according to the echo time difference and a propagation speed of ultrasonic waves in the pipe wall.

[0043] In an embodiment, the time domain average noise reduction method in the preprocessing module includes:

[0044] After digital-to-analog conversion of each channel data of the received signal, the channel data is stored in a time sequence of sampling points;

[0045] At least N data points per second are stored for each channel;

[0046] An average value is calculated for at least the N data points at different time scales.

[0047] In an embodiment, the process of cross-correlation operation in the compensation module includes:

[0048] The preprocessed received signal is cross-correlated with the reference signal;

[0049] The operation process uses a frequency domain fast Fourier transform;

[0050] A cross-correlation function is obtained by calculating a sliding inner product of the two signals, a peak value of the cross-correlation function corresponds to a best alignment time delay of the characteristic signal, and a relative position of the characteristic signal is determined.

[0051] In an embodiment, the amplitude compensation method in the compensation module includes:

[0052] A signal attenuation curve under different lift-off heights is calibrated through experiments, and an amplitude library corresponding to different lift-off heights and ideal signal amplitudes is constructed;

[0053] According to the lift-off height in actual detection, a corresponding ideal signal amplitude is selected from the amplitude library, and a measured amplitude of the characteristic signal is compensated, and the compensation formula is:

[0054] A c =A f e ah ,

[0055] In the formula, A c is a signal amplitude under a measured lift-off environment, A f is an ideal signal amplitude calibrated through lift-off experiments, and a is an attenuation coefficient.

[0056] In an embodiment, the process of multiple echo fitting in the acquisition module includes:

[0057] collecting multiple echo signals generated by reflection of ultrasonic waves in the pipe wall, the multiple echo signals including a primary echo, a secondary echo and subsequent echoes until energy is dissipated;

[0058] determining time differences of the multiple echo signals according to time information of echo amplitude positions, and obtaining echo time differences of linearly corresponding positions by linear fitting.

[0059] In an embodiment, the compensation module further comprises a step of predetermining a group of received signals before determining the relative positions of the characteristic signals, and specifically comprises:

[0060] creating a blank received signal, the length of the blank received signal being the sum of the length of a reference signal and a maximum delay amount, and initializing a zero array as the blank received signal;

[0061] filling the amplitude-scaled reference signal into a specific position of the blank received signal to simulate signal delay effect;

[0062] calculating reference signal power, generating a Gaussian white noise sequence corresponding to the power according to a signal-to-noise ratio, and adding the Gaussian white noise sequence to the blank received signal;

[0063] adding an interference signal to the blank received signal to determine a pre-received signal.

[0064] In an embodiment, the calculation formula of the pipe wall thickness value in the calculation module is:

[0065]

[0066] In the formula, d is the pipe wall thickness, v is the propagation speed of ultrasonic waves in the pipe wall, t n is the echo time difference of linearly corresponding positions.

[0067] In a third aspect, the present application provides an electronic device, comprising: a processor and a memory;

[0068] The memory is configured to store a computer program.

[0069] The processor is configured to execute the electromagnetic ultrasonic internal detection lift-off compensation method provided in any one of the first aspect by calling the computer program.

[0070] In a fourth aspect, the present application provides a computer readable storage medium, the computer readable storage medium comprising a program, the program being configured to implement the electromagnetic ultrasonic internal detection lift-off compensation method provided in any one of the first aspect when executed by a processor.

[0071] The electromagnetic ultrasonic internal detection lift-off compensation method of the embodiment of the present application significantly improves the signal-to-noise ratio of the signal through time domain average noise reduction and low-frequency excitation; the gate and echo time difference are determined by cross-correlation analysis, the method of the embodiment of the present application is not sensitive to noise, and the fluctuation that may exist in a single measurement is further smoothed by multi-echo fitting, and the result is more stable and reliable; the innovative amplitude compensation directly enhances the signal attenuation caused by lift-off, and the multi-echo fitting optimizes the time difference extraction from the statistical level, and the combination of the two solves the lift-off effect problem from the two dimensions of amplitude and time, effectively overcomes the adverse effects of lift-off changes on measurement, significantly improves the precision and robustness of pipeline wall thickness internal detection under complex working conditions, and solves the technical problems of signal attenuation, low echo detection precision and large thickness measurement error caused by lift-off effect in electromagnetic ultrasonic internal detection. BRIEF DESCRIPTION OF DRAWINGS

[0072] Figure 1 Fig. 1 shows a flowchart of an electromagnetic ultrasonic internal detection lift-off compensation method provided by an embodiment of the present application;

[0073] Figure 2 Fig. 2 shows a structural diagram of an electromagnetic ultrasonic internal detection lift-off compensation system provided by an embodiment of the present application;

[0074] Figure 3 Fig. 3 shows a structural diagram of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical scheme and advantages of the present application more clear, specific embodiments of the present application will be further described below with reference to the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0076] Based on the disadvantages of the prior art, the present application provides a specific embodiment of an electromagnetic ultrasonic internal detection lift-off compensation method, as shown in Figure 1 The method specifically includes the following steps:

[0077] S110: configuring a reference signal for electromagnetic ultrasonic internal detection.

[0078] The reference signal is the basis for subsequent signal comparison and time difference determination, and must have the characteristics of easy identification and anti-interference to avoid confusion with the electromagnetic excitation initial wave, and provide a clear comparison reference for subsequent cross-correlation operation.

[0079] The reference signal is a low-frequency excitation signal designed based on finite element numerical simulation analysis. The waveform of the low-frequency excitation signal is a piecewise function, and the piecewise function includes a modulated sine wave segment and a zero function segment.

[0080] The finite element numerical simulation can accurately simulate the excitation and propagation process of the ultrasonic wave based on the material properties, wall thickness and other parameters of the pipeline to be detected, thereby designing an appropriate low-frequency signal. The anti-interference ability of the low-frequency signal is significantly better than that of the high-frequency signal, which can reduce the interference of the complex environment (such as impurities and oil stains) in the pipeline on the signal and avoid the characteristic signal being submerged in the background noise.

[0081] The reference signal adopts the piecewise structure of the modulated sine wave segment and the zero function segment, wherein the zero function segment corresponds to the duration of the electromagnetic excitation initial wave. The effective characteristic segment (modulated sine wave segment) of the reference signal can be completely separated from the initial wave, the characteristic signal can be avoided to be hidden in the initial wave, the difficulty of subsequent cross-correlation operation can be greatly reduced, and the accuracy of the characteristic signal positioning can be improved.

[0082] Through the customized design and segmented waveform optimization of the finite element simulation, the reference signal can adapt to different detection scenarios and can be easily distinguished from the interference signal and the initial wave, thereby providing a high-quality benchmark for subsequent cross-correlation positioning and further improving the positioning accuracy of the characteristic signal.

[0083] S120: The time-domain average noise reduction method is used to pre-process the received signal collected in the electromagnetic ultrasonic internal detection process.

[0084] Random noise is easily mixed into the received signal during the collection process. If not processed, the random noise will cover the peak value characteristics of the echo, resulting in the inability to accurately determine the peak value position subsequently. The time-domain average noise reduction method can filter out most of the random noise while retaining the key peak value characteristic signal, thereby laying a foundation for the positioning of the characteristic signal.

[0085] S130: Based on the reference signal, the relative position of the characteristic signal in the received signal is determined by using the cross-correlation method, and the amplitude of the characteristic signal is compensated in combination with the lift-off height experiment, so as to determine the gate information.

[0086] The lift-off effect will cause the amplitude of the characteristic signal to attenuate and even be submerged in the noise, and the characteristic signal cannot be positioned by using the conventional method. The cross-correlation operation based on the reference signal can accurately lock the relative position of the characteristic signal, and the amplitude compensation of the lift-off height experiment can enhance the amplitude strength of the characteristic signal and clearly define the gate range (i.e. the effective interval of the characteristic signal), thereby avoiding the positioning deviation caused by insufficient amplitude.

[0087] S140: Based on the gate information, the time information corresponding to the position of the characteristic signal is accurately obtained, and then the echo time difference of the linear corresponding position is determined through multiple echo fitting.

[0088] Single echo signal is susceptible to interference, resulting in unstable time difference calculation; through multi-echo fitting, the synergistic effect of multiple echoes can offset the random error of single echo, and a more stable and accurate echo time difference can be obtained, and the echo time difference is the core parameter for calculating the wall thickness.

[0089] S150: calculating the pipeline wall thickness value according to the echo time difference and the propagation speed of ultrasonic waves in the pipeline wall.

[0090] According to the ultrasonic wave propagation principle, the wall thickness and the echo time difference are linearly related, and under the premise that the propagation speed (determined by the pipeline material and the waveform, which can be determined in advance before detection, and the fluctuation is small) is stable, the high-precision pipeline wall thickness value can be calculated based on the accurate echo time difference.

[0091] The embodiment can resist the lift-off effect through the complete process of reference signal, preprocessing, positioning compensation, fitting and calculation, and significantly improve the thickness measurement accuracy of electromagnetic ultrasonic internal detection, and can solve the problems of signal attenuation, inaccurate time difference and large thickness measurement error caused by lift-off.

[0092] In an embodiment of the present application, the frequency setting of the low-frequency excitation signal is based on the wall thickness of the pipeline to be detected, and the frequency of the low-frequency excitation signal is adjusted according to the wall thickness of the pipeline to be detected.

[0093] For a pipeline with a relatively thick wall (such as ≥20mm), the ultrasonic wave propagation path is long, the high-frequency signal is prone to attenuation during propagation, and is easily disturbed by internal defects (such as corrosion pits) of the pipeline. At this time, a lower frequency (such as 50kHz) is set to enhance the signal penetration and anti-interference ability. For a pipeline with a relatively thin wall (such as ≤10mm), the ultrasonic wave propagation path is short, and the frequency can be appropriately increased (such as 100kHz) to ensure anti-interference while improving signal resolution and avoiding echo overlap; before detection, the wall thickness of the pipeline to be detected is obtained through the pipeline specification file, and the propagation effect of signals with different frequencies in the pipeline with the wall thickness is simulated based on finite element simulation, and the frequency with the smallest signal attenuation and the strongest anti-interference ability is selected as the frequency of the final low-frequency excitation signal. Through the wall thickness adaptive frequency setting of the embodiment, the low-frequency excitation signal can maintain the best propagation characteristics and anti-interference ability in pipelines with different wall thicknesses, avoiding signal attenuation or interference caused by improper frequency, and further improving the integrity and recognizability of the characteristic signal.

[0094] In an embodiment of the present application, the time domain average noise reduction method includes:

[0095] After each channel data of the received signal is converted from digital to analog, it is stored in sequence according to the sampling point time;

[0096] At least N data points per second are stored for each channel;

[0097] Calculate the average value of at least N data points at different time scales.

[0098] In practical applications, after each channel of the received signal undergoes digital-to-analog conversion, it is stored in a time sequence according to the sampling points (200 data points per second, i.e., N = 200). This sampling frequency ensures that the complete propagation process of the ultrasonic wave is captured without increasing the computational burden due to excessive data volume. By averaging the 200 data points at different time scales, such as dividing the data into groups according to time scales of 10ms and 20ms and calculating the average value of each group, random noise can be effectively canceled (noise is irregularly distributed at different time scales, and averaging can weaken its influence). At the same time, because the peak signal has stability, averaging will not mask the peak characteristics. The time-domain averaging noise reduction method can filter out random noise while preserving the characteristic information of the echo peak to the greatest extent, providing a reliable signal basis for subsequent peak location and time difference calculation.

[0099] In one embodiment of the present invention, the cross-correlation operation process includes:

[0100] The preprocessed received signal is cross-correlated with the reference signal.

[0101] The calculation process uses frequency domain fast Fourier transform;

[0102] The cross-correlation function is obtained by calculating the sliding inner product of the two signals. The peak value of the cross-correlation function corresponds to the optimal alignment delay of the characteristic signals, thus determining the relative position of the characteristic signals.

[0103] In practical applications, performing cross-correlation calculations directly in the time domain results in an extremely high computational load when the data length is large, which cannot meet the requirements of real-time detection. The Fast Fourier Transform (FFT) in the frequency domain is employed, leveraging the property that frequency-domain multiplication is equivalent to time-domain convolution, significantly improving computational efficiency and adapting to the real-time requirements of pipeline detection. The preprocessed received signal and the reference signal undergo a sliding inner product operation. The peak of the cross-correlation function indicates the highest similarity between the two signals, corresponding to the optimal alignment delay of the feature signals. This delay is the time difference between the feature signals in the reference and received signals, which can be directly used as the basis for the relative position of the feature signals, achieving a positioning accuracy down to the sampling point level and avoiding subjective errors from manual peak judgment. By accelerating the cross-correlation calculation through FFT and utilizing the objective positioning characteristics of the cross-correlation function peak, the efficiency and accuracy of determining the relative position of feature signals are improved, ensuring accurate determination of gate information.

[0104] Based on this embodiment, the determination conditions for gate information are limited, with the core being to ensure that the gate covers the complete feature signal and avoids interference signals. Therefore, making the gate interval greater than or equal to the length of the reference signal ensures that the gate can completely cover the feature signal in the received signal (the feature signal has the same waveform and length as the reference signal), avoiding the exclusion of some feature signals due to an excessively narrow interval, which would affect peak detection.

[0105] By positioning the gate earlier than the time point corresponding to the peak of the cross-correlation function, the rising edge of the characteristic signal can be captured in advance, avoiding missing the initial peak of the characteristic signal due to a late starting position. This also prevents subsequent echoes (such as secondary echoes) or interference signals from entering the gate, ensuring that only the target characteristic signal is contained within it. By appropriately setting the gate's range and starting position, the effective range of the characteristic signal can be accurately defined, eliminating irrelevant interference signals and providing a clean signal range for subsequent amplitude compensation and echo time difference calculations, further reducing errors.

[0106] In one embodiment of the present invention, the amplitude compensation method includes:

[0107] By experimentally calibrating the signal attenuation curves at different lift-off heights, an amplitude library corresponding to the ideal signal amplitude at different lift-off heights was constructed.

[0108] Based on the actual lift-off height detected, the corresponding ideal signal amplitude is selected from the amplitude library to compensate for the measured amplitude of the characteristic signal. The compensation formula is as follows:

[0109] A c =A f e ah ,

[0110] In the formula, A c To measure the signal amplitude under the lift-off environment, A f The ideal signal amplitude is defined for the lift-off experiment, α is the attenuation coefficient, and h is the lift-off height.

[0111] In practical applications, under laboratory conditions, different lift-off heights (e.g., 0.1mm, 0.2mm, ..., 1.0mm, covering the lift-off range of the probe in actual testing) are simulated. Signal attenuation curves are collected at the corresponding lift-off heights, and the ideal signal amplitude A corresponding to each lift-off height is recorded. f (i.e., the theoretical amplitude without noise interference at this lift-off height), construct the lift-off height A. f Amplitude library; this process can eliminate the impact of material property inhomogeneity and complex interface signal feedback on A. f The influence of A f More closely aligned with real-world testing scenarios. During actual testing, the real-time lift-off height h is obtained through the probe's built-in distance sensor, and the corresponding amplitude (A) is retrieved from the amplitude library. fSubstituting into the compensation formula, where α is the attenuation coefficient pre-calibrated experimentally and is related to probe parameters and pipe material, the compensated measured amplitude A is calculated. c The compensated amplitude A c It can restore the amplitude level to near the ideal contact level, avoiding peak blurring caused by amplitude attenuation. Through experimentally calibrated amplitude library and compensation formula, precise amplitude compensation can be achieved for different lift-off heights, solving the amplitude attenuation problem caused by the lift-off effect, making the peak of the characteristic signal clearer, and facilitating the subsequent determination of the peak time point.

[0112] In one embodiment of the present invention, the multi-echo fitting process includes:

[0113] Collect multiple echo signals generated by the reflection of ultrasonic waves inside the pipe wall. The multiple echo signals include the first echo, the second echo, and subsequent echoes until the energy is dissipated.

[0114] The time difference of the multiple echo signals is determined by the time information of the echo amplitude position, and the echo time difference of the linearly corresponding position is obtained by linear fitting.

[0115] In practical applications, when ultrasonic waves propagate within a pipe wall, they reflect multiple times between the inner and outer walls, forming primary echoes (first reflection from the outer wall), secondary echoes (secondary reflections from both inner and outer walls), tertiary echoes, and so on, until the energy dissipates. Collecting these echo signals yields multiple sets of peak time point data, providing sufficient samples for fitting. Data points are constructed by plotting the number of echoes on the x-axis and the time point corresponding to the echo peak on the y-axis. During the fitting process, the ideal echo time difference is used as the fitting benchmark. A straight line is found using the least squares method, minimizing the sum of squared errors between the actual and ideal time points, resulting in a fitted linear model. The slope of this fitted linear model represents the stable echo time difference. By fitting multiple echo samples to the ideal time difference, time difference fluctuations caused by interference in individual echoes can be offset, reducing the error in the echo time difference and significantly improving its stability and accuracy, providing reliable echo time difference parameters for wall thickness calculation.

[0116] In one embodiment of the present invention, before determining the relative position of the feature signals, a step of pre-determining a set of received signals is further included, specifically including:

[0117] Create a blank receive signal. The length of the blank receive signal is the sum of the length of the reference signal and the maximum delay. Initialize an array of all zeros as the blank receive signal.

[0118] The amplitude-scaled reference signal is filled into a specific position of the blank received signal to simulate the signal delay effect;

[0119] Calculate the reference signal power, generate a Gaussian white noise sequence with corresponding power based on the signal-to-noise ratio, and add the Gaussian white noise sequence to the blank received signal;

[0120] An interference signal is added to the blank received signal to determine the pre-received signal.

[0121] The purpose of this embodiment is to simulate the characteristics of the received signal in advance, so as to provide a reference for comparison with the actual signal. In practical applications, the core parameters are first defined, including delay, signal-to-noise ratio (SNR), and signal attenuation factor. The delay is the expected position of the reference signal in the received signal (set based on the propagation time of the ultrasonic wave in the pipe to ensure the position of the reference signal in the pre-received signal matches the actual detection). The SNR is used to determine the power of the added noise (set based on the environment inside the pipe to simulate the actual noise level). The signal attenuation factor is used to simulate the attenuation during signal propagation (set based on the lift-off height to simulate signal propagation attenuation). Then, a blank signal and an implanted reference signal are created. The length of the blank signal is set to the sum of the reference signal length L and the maximum delay D, L+D. An array of all zeros is initialized. Starting from the initial sampling point, a reference signal with amplitude scaling (the scaling factor is the signal attenuation factor) is implanted, keeping the initial sampling point at zero to simulate the time period before the signal arrives. Noise and interference are then added. The power of the reference signal is calculated, and the noise power is calculated based on the SNR. A Gaussian white noise sequence is generated and added to the blank signal. Simultaneously, a power frequency interference signal (simulating on-site power supply interference) is added; other interference signals can also be added. Finally, the pre-received signal is obtained.

[0122] The pre-received signal can simulate the signal characteristics (delay, attenuation, noise, interference) in actual detection, providing a template for feature recognition of the actual received signal. The averaging of the echo time difference between the pre-received signal and the actual received signal can reduce the recognition error of the actual signal caused by the complex environment, improve the accuracy of cross-correlation positioning, and also compensate for the parameters of the echo time difference.

[0123] In one embodiment of the present invention, the formula for calculating the pipe wall thickness is as follows:

[0124]

[0125] In the formula, d is the pipe wall thickness, v is the sound velocity of the ultrasonic wave in the pipe wall, and t is the velocity of the ultrasonic wave. n This represents the echo time difference at the linearly corresponding positions.

[0126] Based on the same inventive concept, this application also provides an electromagnetic ultrasonic intra-operative detection lift-off compensation system, which can be used to implement the electromagnetic ultrasonic intra-operative detection lift-off compensation method described in the above embodiments, as shown in the following embodiments. Since the principle and method of solving the problem are similar, the implementation of the system can refer to the method implementation, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0127] This invention provides an electromagnetic ultrasonic internal detection lift-off compensation system, such as... Figure 2 As shown. In Figure 2 The system includes:

[0128] Configuration module 210: Used to configure a reference signal for electromagnetic ultrasound internal detection;

[0129] Preprocessing module 220: used to preprocess the received signals acquired during the electromagnetic ultrasonic internal detection process using a time-domain averaging noise reduction method;

[0130] Compensation module 230: Used to determine the relative position of the characteristic signal in the received signal based on the reference signal and the cross-correlation method, and to perform amplitude compensation of the characteristic signal in combination with the lift-off height experiment in order to determine the gate information;

[0131] Acquisition module 240: is used to accurately acquire the time information corresponding to the position of the feature signal based on the gate information, and then determine the echo time difference of the linearly corresponding position through multiple echo fitting.

[0132] Calculation module 250: Used to calculate the pipe wall thickness based on the echo time difference and the propagation speed of the ultrasonic wave in the pipe wall.

[0133] In one embodiment of the present invention, the time-domain averaging noise reduction method in the preprocessing module 220 includes:

[0134] The data from each channel of the received signal is converted from digital to analog and then stored in a time sequence according to the sampling points;

[0135] Each channel stores at least N data points per second;

[0136] Calculate the average value of at least N data points at different time scales.

[0137] In one embodiment of the present invention, the cross-correlation calculation process in the compensation module 230 includes:

[0138] The preprocessed received signal is cross-correlated with the reference signal.

[0139] The calculation process uses frequency domain fast Fourier transform;

[0140] The cross-correlation function is obtained by calculating the sliding inner product of the two signals. The peak value of the cross-correlation function corresponds to the optimal alignment delay of the characteristic signals, thus determining the relative position of the characteristic signals.

[0141] In one embodiment of the present invention, the amplitude compensation method in the compensation module 230 includes:

[0142] By experimentally calibrating the signal attenuation curves at different lift-off heights, an amplitude library corresponding to the ideal signal amplitude at different lift-off heights was constructed.

[0143] Based on the actual lift-off height detected, the corresponding ideal signal amplitude is selected from the amplitude library to compensate for the measured amplitude of the characteristic signal. The compensation formula is as follows:

[0144] A c =A f e ah ,

[0145] In the formula, A c To measure the signal amplitude under the lift-off environment, A f The ideal signal amplitude is defined for the lift-off experiment, α is the attenuation coefficient, and h is the lift-off height.

[0146] In one embodiment of the present invention, the process of obtaining multi-echo fitting in module 240 includes:

[0147] Collect multiple echo signals generated by the reflection of ultrasonic waves inside the pipe wall. The multiple echo signals include the first echo, the second echo, and subsequent echoes until the energy is dissipated.

[0148] The time difference of the multiple echo signals is determined by the time information of the echo amplitude position, and the echo time difference of the linearly corresponding position is obtained by linear fitting.

[0149] In one embodiment of the present invention, before determining the relative position of the feature signals, the compensation module 230 further includes a step of pre-determining a set of received signals, specifically including:

[0150] Create a blank receive signal. The length of the blank receive signal is the sum of the length of the reference signal and the maximum delay. Initialize an array of all zeros as the blank receive signal.

[0151] The amplitude-scaled reference signal is filled into a specific position of the blank received signal to simulate the signal delay effect;

[0152] Calculate the reference signal power, generate a Gaussian white noise sequence with corresponding power based on the signal-to-noise ratio, and add the Gaussian white noise sequence to the blank received signal;

[0153] An interference signal is added to the blank received signal to determine the pre-received signal.

[0154] In one embodiment of the present invention, the formula for calculating the pipe wall thickness in the calculation module 250 is as follows:

[0155]

[0156] In the formula, d is the pipe wall thickness, v is the sound velocity of the ultrasonic wave in the pipe wall, and t is the velocity of the ultrasonic wave. n This represents the echo time difference at the linearly corresponding positions.

[0157] This application also provides a specific implementation of an electronic device capable of implementing all the steps in the methods described above. See [link to implementation details]. Figure 3 The electronic device 300 specifically includes the following:

[0158] Processor 310, memory 320, communication unit 330 and bus 340;

[0159] The processor 310, memory 320, and communication unit 330 communicate with each other via bus 340; the communication unit 330 is used to realize information transmission between server-side devices and terminal devices and other related devices.

[0160] The processor 310 is used to call the computer program in the memory 320. When the processor executes the computer program, it implements all the steps in the electromagnetic ultrasonic internal detection lift-off compensation method in the above embodiment.

[0161] Those skilled in the art will understand that memory can be, but is not limited to, Random Access Memory (RAM), Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), and Electrically Erasable Programmable Read-Only Memory (EEPROM). The memory stores programs, which are then executed by the processor upon receiving execution instructions. Furthermore, the software programs and modules within the memory may include an operating system, which may include various software components and / or drivers for managing system tasks (e.g., memory management, storage device control, power management), and can communicate with various hardware or software components to provide an operating environment for other software components.

[0162] A processor can be an integrated circuit chip with signal processing capabilities. The aforementioned processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor.

[0163] This application also provides a computer-readable storage medium including a program, which, when executed by a processor, is used to perform an electromagnetic ultrasonic internal detection lift-off compensation method provided in any of the foregoing method embodiments.

[0164] Those skilled in the art will understand that all or part of the steps in the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks, and this application does not limit the specific type of media.

[0165] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for lifting compensation in electromagnetic ultrasonic intraoperative detection, characterized in that, Includes the following steps: Configure a reference signal for internal electromagnetic ultrasound detection; The received signals acquired during the electromagnetic ultrasonic internal detection process are preprocessed using a time-domain averaging noise reduction method; Based on the reference signal, the relative position of the feature signal in the received signal is determined by the cross-correlation method, and the amplitude of the feature signal is compensated by the lift-off height experiment in order to determine the gate information. Based on the gate information, the time information corresponding to the location of the feature signal is accurately obtained, and then the echo time difference of the linearly corresponding location is determined by multiple echo fittings. The pipe wall thickness is calculated based on the echo time difference and the propagation speed of the ultrasonic wave in the pipe wall.

2. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, The time-domain averaging noise reduction method includes: The data from each channel of the received signal is converted from digital to analog and then stored in a time sequence according to the sampling points; Each channel stores at least N data points per second; Calculate the average value of at least the N data points at different time scales.

3. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, The cross-correlation operation process includes: The preprocessed received signal is cross-correlated with the reference signal; The calculation process uses frequency domain fast Fourier transform; The cross-correlation function is obtained by calculating the sliding inner product of the two signals. The peak value of the cross-correlation function corresponds to the optimal alignment delay of the feature signal, thereby determining the relative position of the feature signal.

4. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, The amplitude compensation method includes: By experimentally calibrating the signal attenuation curves at different lift-off heights, an amplitude library corresponding to the ideal signal amplitude at different lift-off heights was constructed. Based on the actual lift-off height during testing, a corresponding ideal signal amplitude is selected from the amplitude library to compensate for the measured amplitude of the characteristic signal. The compensation formula is as follows: THE c =A f and ah , In the formula, A c To measure the signal amplitude under the lift-off environment, A f The ideal signal amplitude is defined for the lift-off experiment, α is the attenuation coefficient, and h is the lift-off height.

5. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, The multi-echo fitting process includes: Collect multiple echo signals generated by the reflection of ultrasonic waves inside the pipe wall. The multiple echo signals include a first echo, a second echo, and subsequent echoes until the energy is dissipated. The time difference of the multiple echo signals is determined by the time information of the echo amplitude position, and the echo time difference of the linearly corresponding position is obtained by linear fitting.

6. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, Before determining the relative position of the feature signal, the method further includes a step of pre-determining a set of received signals, specifically including: Create a blank receive signal, the length of which is the sum of the reference signal length and the maximum delay. Initialize an array of all zeros as the blank receive signal. The amplitude-scaled reference signal is filled into a specific position of the blank received signal to simulate the signal delay effect; Calculate the reference signal power, generate a Gaussian white noise sequence with corresponding power based on the signal-to-noise ratio, and add the Gaussian white noise sequence to the blank received signal; An interference signal is added to the blank received signal to determine the pre-received signal.

7. The electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in claim 1, characterized in that, The formula for calculating the pipe wall thickness is as follows: In the formula, d is the pipe wall thickness, v is the sound velocity of the ultrasonic wave in the pipe wall, and t is the velocity of the ultrasonic wave. n This represents the echo time difference at the linearly corresponding positions.

8. An electromagnetic ultrasonic internal detection lift-off compensation system, characterized in that, The system includes: Configuration module: Used to configure the reference signal for electromagnetic ultrasound internal testing; Preprocessing module: Used to preprocess the received signals acquired during electromagnetic ultrasonic internal detection using a time-domain averaging noise reduction method; Compensation module: used to determine the relative position of the feature signal in the received signal based on the reference signal using a cross-correlation method, and to perform amplitude compensation on the feature signal in combination with a lift-off height experiment, so as to determine the gate information; Acquisition module: used to accurately acquire the time information corresponding to the position of the feature signal based on the gate information, and then determine the echo time difference of the linearly corresponding position through multiple echo fitting. Calculation module: used to calculate the pipe wall thickness based on the echo time difference and the propagation speed of the ultrasonic wave in the pipe wall.

9. An electronic device, characterized in that, include: Processor and memory; The memory is used to store computer programs; The processor is configured to execute, by invoking the computer program, an electromagnetic ultrasonic intra-operative detection lift-off compensation method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a program that, when executed by a processor, implements the electromagnetic ultrasonic internal detection lift-off compensation method according to any one of claims 1 to 7.

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