CN113008174B - Electromagnetic ultrasonic sound time measuring method and device - Google Patents

Abstract

The present invention provides a method and device for measuring electromagnetic ultrasonic sound time, wherein the method includes: acquiring an induced electrical signal generated by a receiving coil of an electromagnetic ultrasonic transducer; inputting the induced electrical signal into a positive signal whose threshold value is a first preset The voltage comparator obtains the first digital signal, and the negative voltage comparator whose input threshold value is the second preset value obtains the second digital signal; performing an OR operation on the first digital signal and the second digital signal to obtain a third digital signal; Weighting the third digital signal with the pulse width as a weight to obtain a fourth digital signal; converting the fourth digital signal to obtain a reconstructed echo signal; calculating and determining the sound time value according to the reconstructed echo signal. By weighting the third digital signal with the pulse width as the weight, the method filters the noise with short duration and large amplitude, so that the calculation of sound time value can effectively avoid the interference of spike noise and improve the electromagnetic ultrasonic sound quality. precision and accuracy of measurements.

Description

Method and device for measuring electromagnetic ultrasonic sound time

technical field

The invention relates to the technical field of non-destructive testing, in particular to an electromagnetic ultrasonic sound time measuring method and device.

Background technique

Electromagnetic ultrasonic is an emerging non-destructive testing technology. After the excitation coil of the electromagnetic ultrasonic transducer excites ultrasonic waves in the test piece, the ultrasonic waves propagate in the test piece and will be reflected on the upper and lower surfaces. The reflected wave vibration will cut the magnetic induction line in the test piece The induced current is generated in the test piece, and the induced current in the test piece is coupled to the receiving coil, and the time interval between adjacent echoes of the echo signal received by the receiving coil (that is, the acoustic time) reflects the vibration generated by the excited surface of the test piece. The thickness of the test piece can be obtained by combining the time required for the ultrasonic wave to return to the excited surface of the test piece after a reflection, combined with the wave speed of the ultrasonic wave. Therefore, in thickness measurement, the key to electromagnetic ultrasonic signal processing is the measurement of acoustic time.

In the current prior art, the acoustic time is simplified by simply superimposing the electromagnetic ultrasonic signals, increasing the signals proportionally, etc., but it cannot effectively reduce noise, especially the interference of spike noise.

Contents of the invention

An embodiment of the present invention provides a method for measuring electromagnetic ultrasonic sound time to reduce the influence of noise on electromagnetic ultrasonic sound time measurement. The method includes:

Obtain the induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer;

inputting the induced electrical signal into a positive voltage comparator whose threshold value is a first preset value to obtain a first digital signal, and inputting a threshold value to a negative voltage comparator whose threshold value is a second preset value to obtain a second digital signal;

performing an OR operation on the first digital signal and the second digital signal to obtain a third digital signal;

determining a fourth digital signal based on the third digital signal;

performing conversion processing on the fourth digital signal to obtain a reconstructed echo signal;

Calculate and determine the acoustic time value according to the reconstructed echo signal;

Determining a fourth digital signal according to the third digital signal includes:

Traversing the third digital signal at a fixed sampling frequency to determine a plurality of sampling points;

If the amplitude of the first sampling point of the third digital signal is 0, then at the first sampling moment, the amplitude of the fourth digital signal is 0; if the first sampling point of the third digital signal The amplitude of the sampling point is not 0, then at the first sampling moment, the amplitude of the fourth digital signal is the amplitude of the first sampling point of the third digital signal plus one;

Except for the first sampling point, if the amplitude of the sampling point of the third digital signal is 0, then at the sampling moment, the amplitude of the fourth digital signal is 0; if the value of the sampling point of the third digital signal If it is not 0, then at the sampling moment, the amplitude of the fourth digital signal is the amplitude of the fourth digital signal at the previous sampling moment plus one.

The embodiment of the present invention also provides an electromagnetic ultrasonic sound time measuring device, which is used to reduce the influence of noise on the electromagnetic ultrasonic sound time measurement and simplify the processing circuit. The device includes:

The signal acquisition module is used to acquire the induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer;

The second digital signal conversion module is used to input the induced electrical signal to a positive voltage comparator whose threshold value is a first preset value to obtain a first digital signal, and to input a negative voltage comparator whose threshold value is a second preset value The device obtains the second digital signal;

A third digital signal conversion module, configured to perform an OR operation on the first digital signal and the second digital signal to obtain a third digital signal;

A fourth digital signal conversion module, configured to determine a fourth digital signal according to the third digital signal;

A reconstructed echo signal conversion module, configured to convert the fourth digital signal to obtain a reconstructed echo signal;

A calculation module, configured to calculate and determine the acoustic time value according to the reconstructed echo signal;

The fourth digital signal conversion module is specifically used for:

Traversing the third digital signal at a fixed sampling frequency to determine a plurality of sampling points;

If the amplitude of the first sampling point of the third digital signal is 0, then at the first sampling moment, the amplitude of the fourth digital signal is 0; if the first sampling point of the third digital signal The amplitude of the sampling point is not 0, then at the first sampling moment, the amplitude of the fourth digital signal is the amplitude of the first sampling point of the third digital signal plus one;

Except for the first sampling point, if the amplitude of the sampling point of the third digital signal is 0, then at the sampling moment, the amplitude of the fourth digital signal is 0; if the value of the sampling point of the third digital signal If it is not 0, then at the sampling moment, the amplitude of the fourth digital signal is the amplitude of the fourth digital signal at the previous sampling moment plus one.

An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor, and the processor implements the above-mentioned electromagnetic ultrasonic sound time measurement method when executing the computer program .

An embodiment of the present invention also provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program for executing the above-mentioned electromagnetic ultrasonic acoustic measurement method.

In the embodiment of the present invention, the first digital signal is obtained by inputting the obtained induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer to the positive voltage comparator whose threshold value is the first preset value, and input to the threshold value The negative voltage comparator for the second preset value obtains the second digital signal; performs an OR operation on the first digital signal and the second digital signal to obtain a third digital signal; weights the third digital signal with the pulse width as the weight processing to obtain the fourth digital signal; performing low-pass filtering on the fourth digital signal to obtain the reconstructed echo signal; calculating and determining the sound time value according to the reconstructed echo signal; weighting the third digital signal with the pulse width as the weight Processing, the noise with short duration and large amplitude is filtered, so that the calculation of sound time value can effectively avoid the interference of spike noise, and improve the precision and accuracy of electromagnetic ultrasonic sound time measurement.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a schematic diagram of an electromagnetic ultrasonic sound time measurement method in an embodiment of the present invention.

FIG. 2 is a schematic diagram of specific steps of step 102 in the embodiment of the present invention.

FIG. 3 is a schematic diagram of specific steps of step 105 in the embodiment of the present invention.

FIG. 4 is a schematic diagram of specific steps of step 106 in the embodiment of the present invention.

FIG. 5 is a schematic flowchart of a specific application implementation of electromagnetic ultrasonic sound time measurement in an embodiment of the present invention.

Fig. 6 is a schematic diagram of an induced electrical signal generated by a receiving coil in a specific embodiment of the present invention.

FIG. 7 is a schematic diagram of an echo signal Sig0 intercepted in a specific embodiment of the present invention.

FIG. 8 is a schematic diagram of a noise signal N intercepted in a specific embodiment of the present invention.

FIG. 9 is a schematic diagram of the third digital signal Sig3 in a specific embodiment of the present invention.

FIG. 10 is a schematic diagram of the fourth digital signal Sig4 in a specific embodiment of the present invention.

Fig. 11 is a schematic diagram of reconstructed echo signal Sig5 in a specific embodiment of the present invention.

Fig. 12 is a schematic diagram of an electromagnetic ultrasonic sound time measurement device in an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to solve the problem of low measurement accuracy of electromagnetic ultrasonic sound time caused by spike noise interference in the prior art, an embodiment of the present invention provides an electromagnetic ultrasonic sound time measurement method to reduce the influence of noise on electromagnetic ultrasonic sound time measurement, As shown in Figure 1, the method includes:

Step 101: Obtain the induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer;

Step 102: input the induction electrical signal into a positive voltage comparator whose threshold value is a first preset value to obtain a first digital signal, and input a negative voltage comparator whose threshold value is a second preset value to obtain a second digital signal;

Step 103: performing an OR operation on the first digital signal and the second digital signal to obtain a third digital signal;

Step 104: weighting the third digital signal with the pulse width as the weight to obtain the fourth digital signal;

Step 105: converting the fourth digital signal to obtain a reconstructed echo signal;

Step 106: Calculate and determine the acoustic time value according to the reconstructed echo signal.

It can be seen from Fig. 1 that the first digital signal is obtained by inputting the obtained induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer to the positive voltage comparator whose threshold value is the first preset value, and inputting it to the threshold The negative voltage comparator whose value is the second preset value obtains the second digital signal; performs an OR operation on the first digital signal and the second digital signal to obtain a third digital signal; takes the pulse width of the third digital signal as a weight, and performs Weighting processing to obtain the fourth digital signal; performing low-pass filtering processing on the fourth digital signal to obtain the reconstructed echo signal; calculating and determining the sound time value according to the reconstructed echo signal; taking the pulse width as the weight of the third digital signal, performing Weighting processing filters the noise with short duration and large amplitude, so that the calculation of sound time value can effectively avoid the interference of spike noise, and improve the precision and accuracy of electromagnetic ultrasonic sound time measurement.

During specific implementation, firstly, the induced electric signal generated by the receiving coil of the electromagnetic ultrasonic transducer is acquired. The excitation coil and receiving coil of the electromagnetic ultrasonic transducer are installed on the test piece, and the excitation coil of the electromagnetic ultrasonic transducer sends an excitation signal. After coupling, an induced electrical signal is generated in the receiving coil, and the induced electrical signal is collected.

After obtaining the induction electrical signal, input the induction electrical signal into a positive voltage comparator whose threshold value is the first preset value to obtain the first digital signal, and input a negative voltage comparator whose threshold value is the second preset value to obtain the second digital signal Signal, the specific process is shown in Figure 2, including:

Step 201: Determining the signal before the excitation start moment in the intercepted induction electrical signal as a noise signal;

Step 202: Determine the signal of the first preset duration after the first preset moment in the intercepted induction electrical signal as the echo signal; the distance from the first preset moment to the excitation start time is the second preset duration;

Step 203: Input the echo signal into a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and input a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal.

Intercepting the signal before the start time of the excitation is determined as the noise signal N; intercepting the echo signal Sig0 whose duration is _T1 after the start of the excitation _T0 , that is, the distance from the first preset time to the start time of the excitation is the second preset time length _T0 , The first preset duration is T ₁ . Among them, the selection of _T0 should be greater than the blocking time of the electromagnetic ultrasonic amplifier circuit, and it is necessary to make the intercepted echo signal have high amplitude and high signal-to-noise ratio. For example, the basic threshold can be preset, and _T0 is selected so that the intercepted echo signal The amplitude and signal-to-noise ratio _of the wave signal are higher _than the preset basic threshold; the selection of T ₁ needs to be greater than three times the period value of the echo signal; Desirable 10 ~ 500μs.

In a specific embodiment, it is preferable to intercept the periodically changing induction electrical signal and determine it as an echo signal, and determine the periodically changing signal of the first preset duration _T1 after the first preset time in the intercepted induction electrical signal as echo signal.

Input the intercepted echo signal Sig0 into a positive voltage comparator with a threshold value of Thd1 to obtain the first digital signal Sig1, and input a negative voltage comparator with a threshold value of Thd2 to obtain the second digital signal Sig2, and filter out the echo signal low amplitude noise signal.

The threshold setting value Thd1 of the positive voltage comparator can satisfy, for example:

0.5N _pp < Thd1 < V _pp

Among them, N _pp represents the peak-to-peak value of the noise signal N; V _pp represents the peak-to-peak value of the echo signal Sig0.

The threshold setting value Thd2 of the negative voltage comparator can satisfy, for example:

_-Vpp <Thd2< _-0.5Npp

Among them, N _pp represents the peak-to-peak value of the noise signal N; V _pp represents the peak-to-peak value of the echo signal Sig0.

After the first digital signal Sig1 and the second digital signal Sig2 are obtained, an OR operation is performed on the first digital signal Sig1 and the second digital signal Sig2 to obtain a third digital signal Sig3.

The third digital signal Sig3 is weighted by the pulse width, and weighted to obtain the fourth digital signal Sig4. The specific steps include:

Traversing the third digital signal Sig3 with a fixed sampling frequency to determine a plurality of sampling points;

If the amplitude of the first sampling point of the third digital signal Sig3 is 0, then at the first sampling moment, the amplitude of the fourth digital signal Sig4 is 0; if the amplitude of the first sampling point of the third digital signal Sig3 is If the amplitude is not 0, then at the first sampling moment, the amplitude of the fourth digital signal Sig4 is the amplitude of the first sampling point of the third digital signal plus one;

Except for the first sampling point, if the amplitude of the sampling point of the third digital signal Sig3 is 0, then at the sampling moment, the amplitude of the fourth digital signal Sig4 is 0; if the value of the sampling point of the third digital signal Sig3 is not 0 , then at the sampling moment, the amplitude of the fourth digital signal Sig4 is the amplitude of the fourth digital signal Sig3 at the previous sampling moment plus one.

By weighting the pulse width, the reconstruction of the signal amplitude is realized, and the spike noise with short duration and large amplitude is filtered.

After obtaining the fourth digital signal Sig4, convert the fourth digital signal Sig4 to obtain the reconstructed echo signal Sig5, the specific process is shown in Figure 3, including:

Step 301: Perform low-pass filtering processing on the fourth digital signal Sig4;

Step 302: Obtain a plurality of amplitude points of the fourth digital signal after low-pass filtering; the amplitude point is a point at the signal amplitude corresponding to the sampling time in the fourth digital signal after low-pass filtering;

Step 303: Perform fitting processing according to the amplitude points to obtain the reconstructed echo signal Sig5.

Wherein, the value range of the cutoff frequency of the low-pass filter for performing low-pass filtering processing on the fourth digital signal Sig4 may be, for example:

[0.1,0.9]×f _e

f _e represents the frequency of the excitation signal emitted by the excitation coil of the electromagnetic ultrasonic transducer.

The echo signal is reconstructed through the above-mentioned processing of the initial induced electrical signal, so that no additional A/D converter is needed, and the hardware circuit is simplified.

After obtaining the reconstructed echo signal Sig5, calculate and determine the sound time value according to the reconstructed echo signal Sig5, the specific process is shown in Figure 4, including:

Step 401: Obtain the peak value V _p of the reconstructed echo signal according to the reconstructed echo signal;

Step 402: Determine the threshold Thd3 according to the peak value V _p ;

Step 403: According to the threshold Thd3, determine the extreme point in the reconstructed echo signal exceeding the threshold Thd3;

Step 404: According to the extreme point, calculate and determine the sound time value according to the following formula:

T=t ₁ -t ₂

Among them, T represents the acoustic time value; t ₁ represents the moment corresponding to the first extreme point exceeding the threshold Thd3; t ₂ represents the moment corresponding to the second extreme point exceeding the threshold Thd3.

The value of the above threshold Thd3 can be, for example:

[0.3,0.9]× _Vp

Wherein, V _p represents the peak value of the reconstructed echo signal Sig5.

It can be understood that the values of the above-mentioned quantities are only examples, and are only the preferred ranges in the embodiments of the present invention. During implementation, the value ranges can be adjusted according to actual needs. These value ranges all fall within the protection scope of the present invention. Implementation No more details in the example.

A specific example is given below to illustrate how the embodiment of the present invention measures electromagnetic ultrasonic sound. This example is applied to a test piece with a thickness of 8mm and a material of No. 45 steel. The specific process is shown in Figure 5.

The excitation voltage of the sensor is 800V, the excitation frequency is 1MHz, and the bottom of the sensor is lifted 1mm away from the surface of the test piece. First, the sensor is installed on the 8mm test piece, and the induced electrical signal generated by the receiving coil can be obtained, as shown in Figure 6.

Intercept echo signal Sig0 and noise signal N with T ₀ of 40 μs and T ₁ of 120 μs, the obtained echo signal Sig0 is shown in Figure 7, and the peak-to-peak value of echo signal Sig0 is about 4.8; the noise signal is shown in Figure 7 As shown in 8, it can be concluded that the peak-to-peak value of the noise signal N is 2.

According to the peak-to-peak value of the echo signal Sig0 of 4.8 and the peak-to-peak value of the noise signal N of 2, the positive and negative voltage comparator thresholds can be set to +1.2V and -1.2V, and the echo signal Sig0 is input to the set positive and negative voltage comparison The device obtains the first digital signal Sig1 and the second digital signal Sig2.

OR processing is performed on the first digital signal Sig1 and the second digital signal Sig2 to obtain a third digital signal Sig3 as shown in FIG. 9 .

The third digital signal Sig3 is weighted by the pulse width, and the fourth digital signal Sig4 is obtained. The specific process is: traverse the third digital signal Sig3 at 50MHz, if the amplitude of the first sampling point of the third digital signal Sig3 If the value is 0, then at the first sampling moment, the amplitude of the fourth digital signal Sig4 is 0; if the amplitude of the first sampling point of the third digital signal Sig3 is not 0, then at the first sampling moment, The amplitude of the fourth digital signal Sig4 is the amplitude of the first sampling point of the third digital signal plus one;

Except for the first sampling point, if the amplitude of the sampling point of the third digital signal Sig3 is 0, then at this sampling moment, the amplitude of the fourth digital signal Sig4 is 0; if the value of the sampling point of the third digital signal Sig3 is not 0, then at this sampling moment, the amplitude of the fourth digital signal Sig4 is the amplitude of the fourth digital signal Sig3 at the previous sampling moment plus one, and the fourth digital signal Sig4 is obtained as shown in FIG. 10 .

The fourth digital signal Sig4 is passed through a 5th-order Butterworth filter with a cutoff frequency of 500KHz to obtain a plurality of amplitude points of the fourth digital signal after low-pass filtering; The point at the signal amplitude corresponding to the sampling time in the four digital signals; according to the amplitude point, perform fitting processing to obtain the reconstructed echo signal Sig5, as shown in FIG. 11 .

It can be read from Fig. 11 that the peak value V _p of the reconstructed echo signal Sig5 is 7.16, and taking 0.707 V _p as the threshold Thd3, the time difference T corresponding to the first two maximum values exceeding the threshold Thd3 can be obtained as 6.08 μs, that is, the acoustic The time value is 6.08μs.

Based on the same inventive concept, the embodiment of the present invention also provides an electromagnetic ultrasonic sound time measurement device. Since the principle of the problem solved by the device is similar to the electromagnetic ultrasonic sound time measurement method, the implementation of the electromagnetic ultrasonic sound time measurement device can be found in the electromagnetic ultrasonic sound time measurement device. The implementation of the time measurement method, the repetition will not be repeated, the specific structure is shown in Figure 12:

A signal acquisition module 1201, configured to acquire the induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer;

The second digital signal conversion module 1202 is configured to input the induced electrical signal into a positive voltage comparator whose threshold value is a first preset value to obtain a first digital signal, and input a negative voltage comparator whose threshold value is a second preset value obtaining a second digital signal;

The third digital signal conversion module 1203 is configured to perform an OR operation on the first digital signal and the second digital signal to obtain a third digital signal;

A fourth digital signal conversion module 1204, configured to perform weighting processing on the third digital signal with the pulse width as the weight to obtain a fourth digital signal;

The reconstructed echo signal conversion module 1205 is configured to convert the fourth digital signal to obtain the reconstructed echo signal;

Calculation module 1206, configured to calculate and determine the acoustic time value according to the reconstructed echo signal. During specific implementation, the second digital signal conversion module 1202 is specifically configured to: determine the signal before the excitation start moment in the intercepted induced electrical signal as a noise signal;

Determining the signal of the first preset duration after the first preset moment in the intercepted induction electrical signal as the echo signal; the distance from the first preset moment to the excitation start time is the second preset duration;

The echo signal is input to a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and input to a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal.

In a specific embodiment, the fourth digital signal conversion module 1204 is specifically used for:

traverse the third digital signal with a fixed sampling frequency, and determine a plurality of sampling points;

If the amplitude of the first sampling point of the third digital signal is 0, then at the first sampling moment, the amplitude of the fourth digital signal is 0; if the amplitude of the first sampling point of the third digital signal is not is 0, then at the first sampling moment, the amplitude of the fourth digital signal is the amplitude of the first sampling point of the third digital signal plus one;

Except for the first sampling point, if the amplitude of the sampling point of the third digital signal is 0, then at the sampling moment, the amplitude of the fourth digital signal is 0; if the value of the sampling point of the third digital signal is not 0, then at At the sampling moment, the amplitude of the fourth digital signal is the amplitude of the fourth digital signal at the previous sampling moment plus one.

In a specific embodiment, the reconstructed echo signal conversion module 1205 is specifically used for:

performing low-pass filtering processing on the fourth digital signal;

Obtaining a plurality of amplitude points of the fourth digital signal after the low-pass filtering process; the amplitude point is a point at the signal amplitude corresponding to the sampling moment in the fourth digital signal after the low-pass filtering process;

According to the amplitude points, a fitting process is performed to obtain a reconstructed echo signal.

In a specific embodiment, the calculating module 1206 is specifically used for:

According to the reconstructed echo signal, the peak value V _p of the reconstructed echo signal is obtained;

Determine the threshold Thd3 according to the peak value V _p ;

According to the threshold Thd3, determine the extreme point in the reconstructed echo signal exceeding the threshold Thd3;

According to the extreme point, calculate and determine the sound time value according to the following formula:

T=t ₁ -t ₂

Among them, T represents the acoustic time value; t ₁ represents the moment corresponding to the first extreme point exceeding the threshold Thd3; t ₂ represents the moment corresponding to the second extreme point exceeding the threshold Thd3.

An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor, and the above method is implemented when the processor executes the computer program.

An embodiment of the present invention also provides a computer-readable storage medium storing a computer program for executing the above method.

In summary, the electromagnetic ultrasonic sound time measurement method and device provided by the embodiments of the present invention have the following advantages:

The first digital signal is obtained by inputting the obtained induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer into a positive voltage comparator whose threshold value is the first preset value, and the threshold value input to the threshold value is the second preset value The negative voltage comparator of the second digital signal is obtained, and the low-amplitude noise signal is filtered; the first digital signal and the second digital signal are ORed to obtain the third digital signal; the third digital signal is weighted by the pulse width, Perform weighting processing to obtain the fourth digital signal, realize the reconstruction of the signal amplitude, and filter the peak noise with short duration and large amplitude; perform low-pass filtering on the fourth digital signal to obtain the reconstructed echo signal; Reconstruct the echo signal, calculate and determine the sound time value; weight the third digital signal with the pulse width as the weight, and filter the noise with short duration and large amplitude, so that the calculation of the sound time value effectively avoids the peak noise interference, which improves the precision and accuracy of electromagnetic ultrasonic sound measurement. The echo signal is reconstructed by processing the initial induced electric signal, so that no additional A/D converter is needed, and the hardware circuit is simplified.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, apparatuses, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, various modifications and changes may be made to the embodiments of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (15)

1. An electromagnetic ultrasonic sound time measurement method, characterized by comprising:

acquiring an induced electrical signal generated by a receiving coil of the electromagnetic ultrasonic transducer;

inputting the induced electrical signals into a positive voltage comparator with a threshold value of a first preset value to obtain first digital signals, and inputting a negative voltage comparator with a threshold value of a second preset value to obtain second digital signals;

performing an or operation on the first digital signal and the second digital signal to obtain a third digital signal;

determining a fourth digital signal according to the third digital signal;

converting the fourth digital signal to obtain a reconstructed echo signal;

calculating and determining a sound time value according to the reconstructed echo signal;

determining a fourth digital signal from the third digital signal comprises:

traversing the third digital signal at a fixed sampling frequency to determine a plurality of sampling points;

if the amplitude of the first sampling point of the third digital signal is 0, the amplitude of the fourth digital signal is 0 at the first sampling moment; if the amplitude of the first sampling point of the third digital signal is not 0, at the first sampling moment, the amplitude of the fourth digital signal is the amplitude of the first sampling point of the third digital signal plus one;

except for the first sampling point, if the amplitude of the third digital signal sampling point is 0, the amplitude of the fourth digital signal is 0 at the sampling moment; and if the value of the sampling point of the third digital signal is not 0, at the sampling moment, the amplitude of the fourth digital signal is the amplitude of the fourth digital signal at the previous sampling moment plus one.

2. The method of claim 1, wherein obtaining the first digital signal by a positive voltage comparator having an input threshold of the induced electrical signal of a first predetermined value, and obtaining the second digital signal by a negative voltage comparator having an input threshold of a second predetermined value comprises:

determining a signal before an excitation starting moment in the intercepted induction electric signal as a noise signal;

determining a signal with a first preset duration after a first preset time in the intercepted induced electrical signal is started as an echo signal; the distance between the first preset moment and the excitation starting moment is a second preset duration;

and inputting the echo signal into a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and inputting a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal.

3. The method of claim 2, wherein determining the intercepted induced electrical signal as an echo signal at a first predetermined time after a first predetermined time begins comprises:

and determining the intercepted signals which are periodically changed for a first preset time after the first preset time in the induction electric signals is started as echo signals.

4. The method of claim 2 wherein the threshold setting value Thd1 of the positive voltage comparator satisfies:

0.5N _pp ＜Thd1＜V _pp

wherein, N _pp A peak-to-peak value representing the noise signal; v _pp Representing the peak-to-peak value of the echo signal.

5. The method of claim 2, wherein the threshold setting value Thd2 of the negative voltage comparator satisfies:

-V _pp ＜Thd2＜-0.5N _pp

wherein, N _pp A peak-to-peak value representing the noise signal; v _pp Representing the peak-to-peak value of the echo signal.

6. The method of claim 1, wherein performing a conversion process on the fourth digital signal to obtain a reconstructed echo signal comprises:

performing low-pass filtering processing on the fourth digital signal;

obtaining a plurality of amplitude points of the fourth digital signal after low-pass filtering; the amplitude point is a point at a signal amplitude corresponding to the sampling moment in the fourth digital signal after the low-pass filtering processing;

and fitting according to the amplitude points to obtain a reconstructed echo signal.

7. The method of claim 6, wherein a cutoff frequency of a low-pass filter that performs low-pass filtering on the fourth digital signal ranges from:

[0.1,0.9]×f _e

wherein f is _e Representing the frequency of the excitation signal emitted by the excitation coil of the electromagnetic ultrasound transducer.

8. The method of claim 1, wherein calculating a determined acoustic time value from the reconstructed echo signal comprises:

obtaining the peak value V of the reconstructed echo signal according to the reconstructed echo signal _p ；

According to the peak value V _p Determining a threshold value Thd3;

according to the threshold value Thd3, determining an extreme point exceeding the threshold value Thd3 in the reconstructed echo signal;

and according to the extreme point, calculating and determining a sound time value according to the following formula:

T＝t ₁ -t ₂

wherein T represents a sound time value; t is t ₁ Representing the moment corresponding to the first extremum point exceeding said threshold Thd3; t is t ₂ Indicating the moment in time corresponding to the second extreme point exceeding said threshold value Thd 3.

9. The method of claim 8, wherein the threshold value Thd3 ranges from:

[0.3,0.9]×V _p

wherein, V _p Representing the peak of the reconstructed echo signal.

10. An electromagnetic ultrasonic sound time measuring device, comprising:

the signal acquisition module is used for acquiring an induced electric signal generated by the receiving coil of the electromagnetic ultrasonic transducer;

the second digital signal conversion module is used for inputting the induced electrical signal into a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and inputting a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal;

the third digital signal conversion module is used for performing OR operation on the first digital signal and the second digital signal to obtain a third digital signal;

the fourth digital signal conversion module is used for determining a fourth digital signal according to the third digital signal;

the reconstruction echo signal conversion module is used for converting the fourth digital signal to obtain a reconstruction echo signal;

the calculation module is used for calculating and determining a sound time value according to the reconstructed echo signal;

the fourth digital signal conversion module is specifically configured to:

traversing the third digital signal at a fixed sampling frequency to determine a plurality of sampling points;

if the amplitude of the first sampling point of the third digital signal is 0, the amplitude of the fourth digital signal is 0 at the first sampling moment; if the amplitude of the first sampling point of the third digital signal is not 0, at the first sampling moment, the amplitude of the fourth digital signal is the amplitude of the first sampling point of the third digital signal plus one;

except for the first sampling point, if the amplitude of the third digital signal sampling point is 0, the amplitude of the fourth digital signal is 0 at the sampling moment; if the value of the sampling point of the third digital signal is not 0, at the sampling moment, the amplitude of the fourth digital signal is the amplitude of the fourth digital signal at the previous sampling moment plus one.

11. The apparatus of claim 10, wherein the second digital signal conversion module is specifically configured to:

determining a signal before an excitation starting moment in the intercepted induction electric signal as a noise signal;

determining a signal with a first preset duration after a first preset time in the intercepted induction electrical signal is started as an echo signal; the distance between the first preset moment and the excitation starting moment is a second preset duration;

and inputting the echo signal into a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and inputting a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal.

12. The apparatus of claim 11, wherein the reconstructed echo signal transformation module is specifically configured to:

performing low-pass filtering processing on the fourth digital signal;

obtaining a plurality of amplitude points of the fourth digital signal after low-pass filtering; the amplitude point is a point at a signal amplitude corresponding to the sampling moment in the fourth digital signal after the low-pass filtering processing;

and fitting according to the amplitude points to obtain a reconstructed echo signal.

13. The apparatus of claim 10, wherein the computing module is specifically configured to:

obtaining the peak value V of the reconstructed echo signal according to the reconstructed echo signal _p ；

According to the peak value V _p Determining a threshold value Thd3;

according to the threshold value Thd3, determining an extreme point exceeding the threshold value Thd3 in the reconstructed echo signal;

and according to the extreme point, calculating and determining a sound value according to the following formula:

T＝t ₁ -t ₂

wherein T represents a sound time value; t is t ₁ Representing the moment corresponding to the first extremum point exceeding said threshold Thd3; t is t ₂ Indicating the moment in time corresponding to the second extreme point exceeding said threshold value Thd 3.

14. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any of claims 1 to 9 when executing the computer program.

15. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for executing the method of any one of claims 1 to 9.

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