CN113008174B - Electromagnetic ultrasonic sound time measuring method and device - Google Patents
Electromagnetic ultrasonic sound time measuring method and device Download PDFInfo
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Abstract
The invention provides an electromagnetic ultrasonic sound time measuring method and device, wherein the method comprises the following steps: acquiring an induced electrical signal generated by a receiving coil of the electromagnetic ultrasonic transducer; inputting the induction 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; performing OR operation on the first digital signal and the second digital signal to obtain a third digital signal; weighting the third digital signal by taking the pulse width as weight to obtain a fourth digital signal; converting the fourth digital signal to obtain a reconstructed echo signal; and calculating and determining a sound time value according to the reconstructed echo signal. According to the method, the third digital signal is weighted by taking the pulse width as the weight, and noise with short duration and large amplitude is filtered, so that the calculation of the sound time value effectively avoids the interference of spike noise, and the precision and accuracy of electromagnetic ultrasonic sound time measurement are improved.
Description
Technical Field
The invention relates to the technical field of nondestructive testing, in particular to an electromagnetic ultrasonic sound time measuring method and device.
Background
The electromagnetic ultrasonic is a novel nondestructive testing technology, after an electromagnetic ultrasonic transducer exciting coil excites ultrasonic waves in a test piece, the ultrasonic waves propagate in the test piece, the upper surface and the lower surface of the test piece are reflected, reflected wave vibration cuts a magnetic induction line to generate induced current in the test piece, the induced current in the test piece is coupled to a receiving coil, the time interval (namely sound time) between adjacent echo waves of echo signals received by the receiving coil reflects the time required for the ultrasonic waves generated on the excited surface of the test piece to return to the excited surface of the test piece after being reflected once, and the thickness of the test piece can be obtained by combining the wave speed of ultrasonic wave propagation. Therefore, in thickness measurement, the key to electromagnetic ultrasonic signal processing is acoustic time measurement.
In the prior art, when the electromagnetic ultrasonic signals are simply superposed and the sound is simplified in modes of increasing the signals in equal proportion and the like, the noise, especially the interference of spike noise, cannot be effectively reduced.
Disclosure of Invention
The embodiment of the invention provides an electromagnetic ultrasonic sound time measuring method, which is used for reducing the influence of noise on electromagnetic ultrasonic sound time measurement and comprises the following steps:
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; 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.
The embodiment of the present invention further provides an electromagnetic ultrasonic sound time measuring apparatus, for reducing the influence of noise on electromagnetic ultrasonic sound time measurement and simplifying a processing circuit, the apparatus including:
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 a 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.
The embodiment of the invention also provides computer equipment which comprises a memory, a processor and a computer program which is stored on the memory and can be run on the processor, wherein the processor realizes the electromagnetic ultrasonic sound time measuring method when executing the computer program.
Embodiments of the present invention also provide a computer-readable storage medium storing a computer program for executing the electromagnetic ultrasonic sound time measurement method.
In the embodiment of the invention, the acquired induced electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer is input to a positive voltage comparator with a threshold value being a first preset value to obtain a first digital signal, and is input to a negative voltage comparator with a threshold value being a second preset value to obtain a second digital signal; performing OR operation on the first digital signal and the second digital signal to obtain a third digital signal; weighting the third digital signal by taking the pulse width as weight to obtain a fourth digital signal; performing low-pass filtering processing on the fourth digital signal to obtain a reconstructed echo signal; calculating and determining a sound time value according to the reconstructed echo signal; and weighting the third digital signal by taking the pulse width as the weight, and filtering the noise with short duration and large amplitude, so that the calculation of the sound time value effectively avoids the interference of spike noise, and the precision and accuracy of the electromagnetic ultrasonic sound time measurement are improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic diagram of an electromagnetic ultrasonic time measurement method in an embodiment of the present invention.
FIG. 2 is a diagram illustrating a specific step of step 102 in an embodiment of the present invention.
FIG. 3 is a diagram illustrating a specific step of step 105 in an embodiment of the present invention.
FIG. 4 is a diagram illustrating a specific step of step 106 according to an embodiment of the present invention.
Fig. 5 is a flowchart illustrating an implementation of a specific application of the electromagnetic ultrasonic time measurement in the embodiment of the present invention.
Fig. 6 is a schematic diagram of an induced electrical signal generated by the receiving coil according to an embodiment of the present invention.
Fig. 7 is a schematic diagram of an intercepted echo signal Sig0 according to an embodiment of the invention.
Fig. 8 is a schematic diagram of the noise signal N obtained by the embodiment of the present invention.
Fig. 9 is a diagram of a third digital signal Sig3 according to an embodiment of the invention.
Fig. 10 is a diagram illustrating a fourth digital signal Sig4 according to an embodiment of the invention.
Fig. 11 is a schematic diagram of reconstructing the echo signal Sig5 according to an embodiment of the present invention.
Fig. 12 is a schematic diagram of an electromagnetic ultrasonic sound time measuring device in the embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within 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, which is used for reducing the influence of noise on electromagnetic ultrasonic sound time measurement, and as shown in fig. 1, the method includes:
step 101: acquiring an induced electrical signal generated by a receiving coil of the electromagnetic ultrasonic transducer;
step 102: inputting the induction 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;
step 103: performing 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 by taking the pulse width as weight to obtain a fourth digital signal;
step 105: converting the fourth digital signal to obtain a reconstructed echo signal;
step 106: and calculating and determining a sound time value according to the reconstructed echo signal.
As can be seen from fig. 1, 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 with the threshold value being the first preset value, and the second digital signal is obtained by inputting the obtained induced electrical signal to the negative voltage comparator with the threshold value being the second preset value; performing OR operation on the first digital signal and the second digital signal to obtain a third digital signal; weighting the third digital signal by taking the pulse width as weight to obtain a fourth digital signal; performing low-pass filtering processing on the fourth digital signal to obtain a reconstructed echo signal; calculating and determining a sound time value according to the reconstructed echo signal; and weighting the third digital signal by taking the pulse width as weight, and filtering the noise with short duration and large amplitude, so that the interference of spike noise is effectively avoided in the calculation of the sound time value, and the precision and accuracy of the electromagnetic ultrasonic sound time measurement are improved.
When the method is specifically implemented, firstly, an induced electric signal generated by a receiving coil of the electromagnetic ultrasonic transducer is obtained. An exciting coil and a receiving coil of the electromagnetic ultrasonic transducer are installed on a test piece, the exciting coil of the electromagnetic ultrasonic transducer sends out an exciting signal, and after coupling, an induced electrical signal is generated at the receiving coil and is collected.
After the induction electrical signal is obtained, the induction electrical signal is input into a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and a negative voltage comparator with a threshold value of a second preset value is input to obtain a second digital signal, and the specific process is as shown in fig. 2 and includes the following steps:
step 201: determining a signal before an excitation starting moment in the intercepted induction electric signal as a noise signal;
step 202: determining a signal with a first preset duration after a first preset time in the intercepted induction electric signal starts as an echo signal; the distance between the first preset moment and the excitation starting moment is a second preset duration;
step 203: 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.
Intercepting a signal before an excitation starting moment to determine as a noise signal N; intercepting the excitation onset T 0 The rear time length is T 1 Is the first predetermined time, i.e. the echo signal Sig0The distance from the excitation starting moment to a second preset time length T 0 The first preset duration is T 1 . Wherein, T 0 Is selected to be larger than the blocking time of the electromagnetic ultrasonic amplifying circuit and is required to make the intercepted echo signal have high amplitude and high signal-to-noise ratio, for example, the basic threshold value can be preset, T is selected 0 Enabling the amplitude value and the signal-to-noise ratio of the intercepted echo signal to be higher than a preset basic threshold value; t is a unit of 1 The selection of the echo signal is required to be more than three times of the echo signal period value; after several trials, in general, T 0 For example, 30 to 150. Mu.s, T may be used 1 For example, it is preferably 10 to 500. Mu.s.
In a specific embodiment, the induced electrical signal with periodic variation is preferably intercepted and determined as an echo signal, and a first preset time length T is preset after a first preset time in the intercepted induced electrical signal starts 1 The periodically varying signal of (2) is determined as an echo signal.
And inputting the intercepted echo signal Sig0 into a positive voltage comparator with a threshold value Thd1 to obtain a first digital signal Sig1, and inputting a negative voltage comparator with a threshold value Thd2 to obtain a second digital signal Sig2, so that low-amplitude noise signals in the echo signal are filtered.
The threshold value setting value Thd1 of the positive voltage comparator may satisfy, for example:
0.5N pp <Thd1<V pp
wherein, N pp Represents the peak-to-peak value of the noise signal N; v pp Indicating the peak-to-peak value of the echo signal Sig 0.
The threshold value setting value Thd2 of the negative voltage comparator may satisfy, for example:
-V pp <Thd2<-0.5N pp
wherein N is pp Represents the peak-to-peak value of the noise signal N; v pp Indicating the peak-to-peak value of the echo signal Sig 0.
After the first digital signal Sig1 and the second digital signal Sig2 are obtained, the first digital signal Sig1 and the second digital signal Sig2 are subjected to or operation to obtain a third digital signal Sig3.
Weighting the third digital signal Sig3 by taking the pulse width as the weight to obtain a fourth digital signal Sig4, wherein the method specifically comprises the following steps:
traversing the third digital signal Sig3 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 Sig3 is 0, the amplitude of the fourth digital signal Sig4 is 0 at the first sampling moment; if the amplitude of the first sampling point of the third digital signal Sig3 is not 0, the amplitude of the fourth digital signal Sig4 is the amplitude of the first sampling point of the third digital signal plus one at the first sampling moment;
except for the first sampling point, if the amplitude of the sampling point of the third digital signal Sig3 is 0, the amplitude of the fourth digital signal Sig4 is 0 at the sampling moment; if the value of the sampling point of the third digital signal Sig3 is not 0, the amplitude of the fourth digital signal Sig4 at the sampling time is the amplitude of the fourth digital signal Sig3 at the previous sampling time plus one.
Through weighting processing according to pulse width, reconstruction of signal amplitude is achieved, and spike noise with short duration and large amplitude is filtered.
After the fourth digital signal Sig4 is obtained, the fourth digital signal Sig4 is converted to obtain a reconstructed echo signal Sig5, and a specific process is shown in fig. 3 and includes:
step 301: performing low-pass filtering processing on the fourth digital signal Sig 4;
step 302: 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 time in the fourth digital signal after the low-pass filtering processing;
step 303: and fitting according to the amplitude points to obtain a reconstructed echo signal Sig5.
The cut-off frequency value range of the low-pass filter for performing the low-pass filtering process on the fourth digital signal Sig4 may be, for example:
[0.1,0.9]×f e
f e representing the frequency of the excitation signal emitted by the excitation coil of the electromagnetic ultrasonic transducer.
The echo signal is reconstructed by the processing of the initial induced electrical signal, so that an A/D converter does not need to be additionally arranged, and a hardware circuit is simplified.
After the reconstructed echo signal Sig5 is obtained, a sound time value is calculated and determined according to the reconstructed echo signal Sig5, and a specific process is shown in fig. 4 and includes:
step 401: obtaining the peak value V of the reconstructed echo signal according to the reconstructed echo signal p ;
Step 402: according to peak value V p Determining a threshold value Thd3;
step 403: according to the threshold value Thd3, determining an extreme point exceeding the threshold value Thd3 in the reconstructed echo signal;
step 404: 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 time corresponding to the first extremum point exceeding the threshold Thd3; t is t 2 Indicating the moment corresponding to the second extreme point exceeding the threshold value Thd 3.
The threshold value Thd3 may be, for example:
[0.3,0.9]×V p
wherein, V p Indicating the peak of the reconstructed echo signal Sig5.
It should be understood that the values of the above quantities are only examples, and are only preferred ranges in the embodiments of the present invention, and the value ranges may be adjusted according to actual needs during implementation, and all of the value ranges fall within the protection range of the present invention, and no further description is given in the embodiments.
A specific example is given below to illustrate how embodiments of the present invention measure electromagnetic ultrasound. The example is applied to a test piece with the thickness of 8mm and the material of 45 steel, and the specific process is shown in figure 5.
The excitation voltage of the sensor is 800V, the excitation frequency is 1MHz, and the distance from the bottom end of the sensor to the surface of the test piece is 1mm. First, the sensor is mounted on an 8mm test piece, and an induced electrical signal generated by the receiving coil can be obtained, as shown in fig. 6.
Intercept T 0 Is 40 mus, T 1 120 μ s of echo signal Sig0 and noise signal NAs shown in fig. 7, the peak-to-peak value of the obtained echo signal Sig0 is about 4.8; noise signal as shown in fig. 8, the peak-to-peak value of the noise signal N can be found to be 2.
According to the peak-to-peak value 4.8 of the echo signal Sig0 and the peak-to-peak value 2 of the noise signal N, the threshold values of the positive and negative voltage comparators can be set to +1.2V and-1.2V, and the echo signal Sig0 is input into the set positive and negative voltage comparators to obtain a first digital signal Sig1 and a second digital signal Sig2.
The first digital signal Sig1 and the second digital signal Sig2 are ored to obtain a third digital signal Sig3 as shown in fig. 9.
Weighting the third digital signal Sig3 by using the pulse width as a weight to obtain a fourth digital signal Sig4, wherein the specific process is as follows: traversing the third digital signal Sig3 by 50MHz, 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 not 0, the amplitude of the fourth digital signal Sig4 is the amplitude of the first sampling point of the third digital signal plus one at the first sampling moment;
except for the first sampling point, if the amplitude of the sampling point of the third digital signal Sig3 is 0, 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, at this sampling time, the amplitude of the fourth digital signal Sig4 is the amplitude of the fourth digital signal Sig3 at the previous sampling time plus one, and the fourth digital signal Sig4 is obtained as shown in fig. 10.
Passing the fourth digital signal Sig4 through a 5-order Butterworth filter with the cut-off frequency of 500KHz to obtain a plurality of amplitude points of the fourth digital signal after low-pass filtering processing; 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; according to the amplitude points, fitting processing is performed to obtain a reconstructed echo signal Sig5, as shown in fig. 11.
The peak value V of the reconstructed echo signal Sig5 can be read out from fig. 11 p At 7.16, take 0.707V p As the threshold value Thd3, the first two can be obtainedThe maximum value exceeding the threshold value Thd3 corresponds to a time difference T of 6.08 μ s, i.e. a sound value of 6.08 μ s.
Based on the same inventive concept, embodiments of the present invention further provide an electromagnetic ultrasonic sound time measurement apparatus, and because the principle of the problem solved by the apparatus is similar to the electromagnetic ultrasonic sound time measurement method, the implementation of the electromagnetic ultrasonic sound time measurement apparatus can refer to the implementation of the electromagnetic ultrasonic sound time measurement method, and the repeated parts are not repeated, and the specific structure is as shown in fig. 12:
a signal acquiring module 1201, configured to acquire an induced electrical signal generated by a receiving coil of the electromagnetic ultrasonic transducer;
the second digital signal conversion module 1202 is configured to input the sensing electrical signal into a positive voltage comparator with a threshold value being a first preset value to obtain a first digital signal, and input into a negative voltage comparator with a threshold value being a second preset value to obtain a second digital signal;
a third digital signal conversion module 1203, configured to perform 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 pulse width as weight, to obtain a fourth digital signal;
a reconstructed echo signal conversion module 1205, configured to perform conversion processing on the fourth digital signal to obtain a reconstructed echo signal;
and a calculating module 1206, configured to calculate and determine a sound time value according to the reconstructed echo signal. In specific implementation, the second digital signal conversion module 1202 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 electric 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.
In a specific embodiment, the fourth digital signal conversion module 1204 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.
In a specific embodiment, the reconstruction echo signal conversion module 1205 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.
In a specific embodiment, the calculating module 1206 is specifically configured to:
obtaining the peak value V of the reconstructed echo signal according to the reconstructed echo signal p ;
According to 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 the threshold Thd3; t is t 2 Indicating the moment corresponding to the second extreme point exceeding the threshold value Thd 3.
The embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method when executing the computer program.
An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program for executing the method.
In summary, the electromagnetic ultrasonic sound time measuring method and the device provided by the embodiment of the invention have the following advantages:
the obtained induction electrical signal generated by the receiving coil of the electromagnetic ultrasonic transducer is input to a positive voltage comparator with a threshold value of a first preset value to obtain a first digital signal, and is input to a negative voltage comparator with a threshold value of a second preset value to obtain a second digital signal, so that a low-amplitude noise signal is filtered; performing OR operation on the first digital signal and the second digital signal to obtain a third digital signal; weighting the third digital signal by taking the pulse width as weight to obtain a fourth digital signal, realizing reconstruction of signal amplitude, and filtering spike noise with short duration and larger amplitude; performing low-pass filtering processing on the fourth digital signal to obtain a reconstructed echo signal; calculating and determining a sound time value according to the reconstructed echo signal; and weighting the third digital signal by taking the pulse width as the weight, and filtering the noise with short duration and large amplitude, so that the calculation of the sound time value effectively avoids the interference of spike noise, and the precision and accuracy of the electromagnetic ultrasonic sound time measurement are improved. The echo signal is reconstructed by processing the initial induction electric signal, so that an A/D converter is not required to be additionally arranged, and a hardware circuit is simplified.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, the present invention may 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, and the like) 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 will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the embodiment of the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in 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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