Multi-channel ultrasonic thickness measurement device and method

Abstract

The present invention provides a multi-channel ultrasonic thickness measurement device and method, the device comprising: an ultrasonic probe array for receiving and generating ultrasonic signals; an ultrasonic hardware module for receiving and processing echo signals emitted by an ultrasonic sensor; a data processing module comprising a data acquisition card for collecting and storing the waveform of ultrasonic echo signals to provide data support. The present invention utilizes the ultrasonic propagation characteristics and the research mechanism of ultrasonic reflection and transmission, connects the multi-channel ultrasonic probe to a single-chip microcomputer through a channel control module, connects the single-chip microcomputer to a host computer through a USB communication module, and uses an improved adaptive Gaussian echo cross-correlation algorithm to calculate the transit time, and finally measures the inner diameter of the pipeline according to the ultrasonic thickness measurement principle, and then calculates the cross-sectional area of ​​the pipeline. It can achieve non-interference with the flow of the fluid, and can realize online monitoring, providing a new idea for the pipeline inner diameter measurement control method.

Description

Technical Field

[0001] The invention belongs to the field of pipeline thickness measurement, and in particular relates to a multi-channel ultrasonic thickness measurement device and method. Background Art

[0002] Ultrasonic thickness measurement is a thickness measurement method that uses the principle of ultrasonic wave propagation and reflection in the target to be measured. The upper computer sends instructions to the ultrasonic probe through the control system. The ultrasonic probe sends out an ultrasonic initial wave signal, which enters the interior of the object to be measured through the coupling agent. During the transmission process, a sound wave signal, an interface wave and a bottom echo are reflected back from the upper and lower surfaces of the target to be measured. The thickness of the target to be measured can be measured by processing the phase difference between the interface wave and the bottom echo by the terminal. At present, the ultrasonic thickness measurement technology of a single probe is mature. Based on the principle of ultrasonic thickness measurement, the present invention realizes a multi-channel ultrasonic thickness measurement device. By adopting an improved adaptive Gaussian echo cross-correlation algorithm, real-time online measurement of the inner diameter of the pipeline can be achieved, and the measurement accuracy can be significantly improved. Summary of the invention

[0003] The object of the present invention is to provide a device and method for ultrasonic thickness measurement of a sound channel.

[0004] The technical solution of the present invention is as follows:

[0005] A multi-channel ultrasonic thickness measuring device, comprising:

[0006] An ultrasonic probe array, used for receiving and generating ultrasonic signals;

[0007] Ultrasonic hardware module, used to receive and process the echo signal sent by the ultrasonic sensor.

[0008] The data processing module includes a data acquisition card, which is used to collect and store the waveform of the ultrasonic echo signal and provide data support.

[0009] Furthermore, the ultrasonic probe array includes 8 ultrasonic probes.

[0010] Furthermore, the ultrasonic hardware module includes an ultrasonic excitation module, an ultrasonic receiving module, a power supply module, and a communication module;

[0011] The ultrasonic excitation module is used to generate and send ultrasonic signals;

[0012] The ultrasonic receiving module is used to process the echo signal emitted by the ultrasonic sensor and send the ultrasonic echo signal to the data acquisition card;

[0013] The power supply module is used to convert 220V AC power into the required voltage;

[0014] The communication module is used for communication between the host computer and the hardware module described in the ultrasonic wave, monitoring the system status and controlling the working mode.

[0015] Furthermore, the ultrasonic excitation module and the ultrasonic receiving module are directly connected to the ultrasonic probe array.

[0016] The present invention also provides a multi-channel ultrasonic thickness measurement method, the method comprising:

[0017] Acquiring ultrasonic echo data;

[0018] An improved adaptive Gaussian echo cross-correlation algorithm is used to analyze and process the waveform of the ultrasonic echo, and the time difference between the reflected waves of the first main multiple Gaussian ultrasonic echo and the transit time difference between the third Gaussian echo peak and the first main Gaussian echo peak are obtained;

[0019] The pipeline diameter is measured using the pipeline diameter calculation formula of the ultrasonic echo algorithm to obtain the pipeline diameter value.

[0020] Furthermore, the pipe diameter calculation formula of the ultrasonic echo algorithm is:

[0021] D 1 =Dv×Δt

[0022] Where:

[0023] D——pipeline outer diameter, m;

[0024] D 1 ——Inner diameter of the pipe, m;

[0025] v——the velocity of ultrasonic waves in the pipe material, m / s;

[0026] Δt – the time interval from the first echo to the third echo, s.

[0027] Furthermore, the improved adaptive Gaussian echo cross-correlation algorithm is specifically:

[0028] The preset Gaussian echo signal is used to perform cross-correlation with the received Gaussian echo signal to calculate multiple cross-correlation peaks. The cross-correlation signal is subjected to power spectrum analysis by frequency domain compression. The power spectrum contains the different power values ​​of each frequency component of the function. The power is calculated for each frequency point and finally plotted as a power spectrum function.

[0029] Furthermore, the calculation formula of the power spectrum is as follows:

[0030]

[0031] Where:

[0032] N is the length of the discrete signal,

[0033] f k ——the frequency of the kth frequency point,

[0034] x(n) is the amplitude of the sampled signal at the nth moment.

[0035] Technical effects of the present invention:

[0036] The present invention utilizes the ultrasonic propagation characteristics and the research mechanism of ultrasonic reflection and transmission, connects the multi-channel ultrasonic probe to the single-chip microcomputer through the channel control module, connects the single-chip microcomputer to the host computer through the USB communication module, and uses the improved adaptive Gaussian echo cross-correlation algorithm to calculate the transit time. Finally, the inner diameter of the pipeline is measured according to the ultrasonic thickness measurement principle, and the cross-sectional area of ​​the pipeline can be calculated. It can achieve no interference with the flow of the fluid and can realize online monitoring, providing a new idea for the pipeline inner diameter measurement control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the embodiments of the invention. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0038] Figure 1 The hardware logic block diagram of the multi-channel ultrasonic pipeline measurement system of the present invention is shown;

[0039] Figure 2 The schematic diagram of the ultrasonic excitation unit circuit of the present invention is shown;

[0040] Figure 3 The schematic diagram of the ultrasonic receiving unit circuit of the present invention is shown;

[0041] Figure 4 The connection circuit schematic diagram of the present invention is shown;

[0042] Figure 5 The circuit schematic diagram of the AC-DC conversion module of the present invention is shown;

[0043] Figure 6 The schematic diagram of the DC-DC boost circuit module of the present invention is shown;

[0044] FIG7( a ) shows the implementation circuit of a DC5V power supply;

[0045] FIG7( b ) shows the implementation circuit of the DC-5V power supply;

[0046] FIG7( c ) shows the implementation circuit of a DC 3.3 V power supply;

[0047] Figure 8 The schematic diagram of the MCU communication auxiliary circuit of the present invention is shown;

[0048] Fig. 9 A schematic diagram showing the components of the multi-channel ultrasonic pipeline measurement system of the present invention is shown;

[0049] Fig.10 A data processing algorithm flow chart of the present invention is shown;

[0050] Fig.11 A schematic diagram of establishing a pipeline ultrasonic propagation echo model of the present invention is shown;

[0051] Fig.12 The echo cross-correlation calculation result diagram of the present invention is shown;

[0052] Fig.13 The original cross-correlation signal power spectrum diagram of the present invention is shown;

[0053] Fig.14 The power spectrum of the cross-correlation signal after frequency domain compression of the present invention is shown;

[0054] Fig.15 The first echo cross-correlation signal diagram after frequency domain compression of the present invention is shown;

[0055] Fig.16 The third echo cross-correlation signal diagram after frequency domain compression of the present invention is shown. DETAILED DESCRIPTION

[0056] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0057] The embodiment of the present invention provides a multi-channel ultrasonic thickness measurement device and method, specifically,

[0058] By evenly arranging 8 ultrasonic probes on the same cross section of the pipeline side wall, the 8 ultrasonic probes are connected to the single-chip microcomputer through the channel communication module to control the operation of each ultrasonic probe; the single-chip microcomputer is connected to the host computer through the USB communication module; through these 8 ultrasonic probes, the inner diameter of the pipeline can be measured according to the ultrasonic thickness measurement principle. The present invention focuses on optimizing the design of ultrasonic transceiver hardware circuits, control chips and peripheral circuits, measurement power supply circuit boards, ultrasonic probe and control system connection circuits, etc., to ensure that the measurement results obtained by the present invention have a large amount of information, reduce calculation errors, and effectively improve thickness measurement accuracy.

[0059] First, select a suitable ultrasonic sensor and probe, and each probe is connected to the designed hardware connection part through an ultrasonic connecting line. After the probe is installed, it is fixed by a fixing device. The ultrasonic thickness measuring probe is a dual crystal probe. So it can be used as a receiver and a transmitter to receive and generate ultrasonic signals. The ultrasonic excitation module and the ultrasonic receiving module are the parts directly connected to the ultrasonic probe, which are responsible for the excitation of ultrasonic waves and the reception of echoes. The control chip and peripheral circuit of ultrasonic emission and reception control the emission and reception of ultrasonic waves, and process signals to improve detection accuracy and reliability. In the present invention, the embedded chip STM32F407ZET6 is used to control the entire set of ultrasonic transceiver circuits. This chip architecture includes multiple parts. For the functions of ultrasonic emission and reception involved in the present invention, and the functions of controlling different working modes of ultrasonic probes, high-speed I / O, USART, DAC and other resources are mainly used. The power supply circuit board usually includes multiple power interfaces and power modules. It mainly includes an AC to DC power supply module and a high-voltage power supply module. These modules are responsible for the power supply of the ultrasonic transceiver measurement hardware circuit board. In addition, the power supply management and monitoring module can also monitor changes in current and voltage and adjust the power supply in time to protect the measurement board from damage.

[0060] In terms of algorithms, the algorithm of this equipment realizes the time difference extraction of a single waveform of the reflected ultrasonic echo, as well as the time difference extraction of the third main Gaussian echo and the first main multiple Gaussian echo. Through the waveform analysis of the pipeline, the cross-correlation algorithm is considered, and the preset Gaussian echo signal is cross-correlated with the received Gaussian echo signal to calculate multiple cross-correlation peaks. The cross-correlation signal is improved by frequency domain compression. Finally, the arrival time difference of each reflected echo of the first main Gaussian echo and the transit time difference between the third Gaussian echo peak and the first main Gaussian echo peak are found to solve the pipe wall thickness and pipe diameter.

[0061] Working principle:

[0062] The hardware module of the present invention comprises an ultrasonic excitation module, an ultrasonic receiving module, a power supply module and a communication module.

[0063] The ultrasonic excitation module consists of an oscillation circuit, an amplifier, a drive circuit and an ultrasonic probe, and is used to generate and send ultrasonic signals.

[0064] The ultrasonic receiving module includes a signal input module, a preamplifier, a filter, a post-amplifier and a post-filter, and is used to receive and process the echo signal emitted by the ultrasonic sensor.

[0065] The power supply module is used to convert 220V AC power into the required voltage.

[0066] The communication module is used for communication between the host and the hardware module, monitoring the system status and controlling the working mode.

[0067] The data processing module includes a data acquisition card, which is used to collect and store the waveform of the ultrasonic echo signal to provide data support for subsequent analysis.

[0068] The software module of the present invention adopts an improved adaptive Gaussian echo cross-correlation algorithm. The algorithm first uses a preset single Gaussian echo signal to perform a cross-correlation operation with the echo signal to find the peak of the cross-correlation. Then, the signal is spectrally analyzed by power spectrum analysis, and the peak of the cross-correlation signal is made more prominent by frequency domain compression, and the time difference of multiple Gaussian echoes is calculated. Then, envelope peak extraction is performed to calculate the time difference of the sound wave arrival of multiple echoes and the transit time of the first echo and the third echo. Finally, the pipeline cross-section is modeled, and the measurement results are corrected in the presence of bubbles to improve accuracy.

[0069] like Figure 2 The figure shows the circuit schematic of the ultrasonic excitation unit. Among them, PLUSE_OUT1 is directly connected to the positive pole of the ultrasonic probe, and MCU_PULSE is the control signal of the MCU, which is output by the PE9 port of the chip. When the switch HFD3 / 24 is turned to 4, the entire ultrasonic excitation circuit is turned on, and the high-voltage power supply drives the ultrasonic circuit power supply through the Π filter circuit composed of C10, L2, and C11. Capacitor C3 is the excitation capacitor, and R2 is the charging resistor, which charges C3 through R2. The excitation process is as follows:

[0070] (1) When Q1 is off and C3 is fully charged, the voltage on the left is 70V and the voltage on the right is close to 0V.

[0071] (2) Q1 is turned on, the left side of C3 is pulled to GND through Q1, and the right side excites a -100 V voltage, which enters the PLUSE_OUT port through D1 and enters the positive pole of the ultrasonic sensor. The negative pole of the sensor is normally connected to GND. At this time, a 70 V voltage signal is applied to the ultrasonic sensor.

[0072] (3) The opening time of Q1 is 100ns, that is, the excitation time of the excitation signal is 100nS. The ultrasonic sensor sends an excitation high signal for 100ns and is closed for 100ns, so the excitation frequency is 5MHz.

[0073] (4) After the excitation output, the ultrasonic sensor and C3 form an LC resonant circuit, and the sensor generates a continuous excitation signal.

[0074] BSC16DN25NS3 is an N-channel driver MOSFET with a withstand voltage of 150V, a current of 40A, a maximum drain voltage of 500mV, and an on-resistance of 18.5. It is mainly used as a low-voltage switch, which can control the output of a high level at a low level to achieve control of the circuit. It has the advantages of small on-resistance, high withstand voltage, and high reliability. It is particularly suitable for controlling the high voltage and high current of ultrasonic probes with low voltage and low current, and has very good stability.

[0075] SL27517 is another key chip in the circuit. It is a single-channel 4A high-speed low-side gate driver that can efficiently and safely drive MOSFET, IGBT and emerging wide bandgap power devices. The wide range of VDD supply voltage from 4.5V to 20V can effectively drive MOSFET. The integrated UVLO protection function ensures that the output remains at a low level under abnormal conditions. Each MOSFET is configured with an SL27517 driver, and the microcontroller gives the same drive signal to the SL27517, while the circuit delay is generated in the SL27517 itself. Under the same parameters, the delay is 1ns. This method can not only ensure the simultaneity of excitation, but also greatly ensure the driving capability.

[0076] like Figure 3 The figure shows the circuit schematic of the ultrasonic receiving unit. The echo signal of the ultrasonic probe enters from SIN_IN, and the DC component is filtered out by C47. R20 and DD1 form a limiting circuit to prevent the echo signal from being too high and causing damage to the circuit. C48 and R24 form a high-pass filter circuit with a cut-off frequency of 723KHz to filter out the ripple signal brought in by the switching power supply in the circuit.

[0077] U2A is the first-stage amplifier circuit, R18 is an adjustable potentiometer, and the circuit's amplification factor is 1-100 times. The operational amplifier uses TPH2502, which is a high-precision operational amplifier chip with ultra-low offset voltage, offset current and noise, making it perform well in high-precision amplification applications, so it is selected as the operational amplifier of the ultrasonic receiving circuit. Its Vos is 50 and its bandwidth is 250MHz. The main function is to amplify the input signal and provide a stable amplification gain. It is usually used to amplify low-level signals, filter, integrate, etc.

[0078] After the first stage of amplification, the signal passes through a high-pass filter composed of C45 and R21 with a cut-off frequency of 1.06MHz, which is used to filter out invalid signals introduced by the power supply during the amplification process.

[0079] The principle of the second stage amplification is the same as that of the first stage amplification, which is a fixed multiple of 100 times. After amplification, it is also connected to a high-pass filter and provided to SING_SCOPE1. The signal can be output for collection by a high-speed AD acquisition card.

[0080] Since the maximum supply voltage of the op amp is 5V, the system is powered by a ±2.3V power supply. The 5V power supply passes through a 2.7V voltage regulator tube to generate a 2.7V voltage drop, and the remaining 2.3V is used to power the op amp through an inductor.

[0081] like Figure 4 The following is a schematic diagram of the connection circuit. If the system specifies that the ultrasonic excitation signal is output to one probe of the dual crystal probe, the signal echo is received by the other probe, so it is necessary to pay attention to the corresponding relationship between the two probes during installation in order to receive an echo with a better signal-to-noise ratio.

[0082] The power supply circuit board usually includes multiple power interfaces and power modules. It mainly includes an AC to DC power module and a high-voltage power module. The present invention uses an AC 220V power supply, so the device selection is the LHE60-20B12 module of Jinshengyang, which generates a 12V / 5A DC power supply. Figure 5 The figure shows the circuit schematic of the AC-DC conversion module. Among them, F1 is the fuse of the power supply to prevent the power supply part from being damaged by circuit failure. R2 is a varistor to suppress the voltage pulse in the power supply network. D1 is a transient diode to prevent the output of the AC-DC module from generating high voltage instantly and play a role in absorbing instantaneous energy.

[0083] In addition, since the ultrasonic probe requires a higher voltage (up to 70V) to drive, the 12V voltage provided by the AC-DC conversion module is not enough to meet the requirement. Therefore, a high-voltage power supply is required. The HO1-P401V-5C module of Jinshengyang is selected to complete the DC-DC DC boost task. The input voltage of this module is DC12V, and the output voltage is DC0-400V. The output voltage can be adjusted by the analog quantity provided by the microcontroller. Figure 6 Shown is the circuit schematic of this module:

[0084] Generally speaking, a power supply circuit is essential for a chip to work. STM32 requires a 3.3V power supply, and the other peripheral circuits require 4 voltages of power supply: DC12V, DC5V, DC-5V, and DC3.3V. Except for the 12V voltage which can be directly input through the power board, the other three voltages of power supply require additional circuit design. Therefore, the peripheral circuit power supply module was designed in the early stage of design to generate the corresponding circuits of the other three low-voltage power supply modules, as shown in Figure 7:

[0085] Figure 7(a) is the implementation circuit of the DC5V power supply. The selected device is XL1509-5.0, a high-efficiency DC / DC step-down chip, which outputs 5V voltage by receiving the 12V voltage of the front power supply circuit board. Its input voltage range is 4.5V~40V, and its output voltage range is 1.25V~37V. Its maximum output current is 4A, which is a huge advantage compared to other similar power modules. At the same time, it also has built-in over-temperature and over-voltage protection circuits, and the output ripple is very small, which is very beneficial to the operation of the ultrasonic amplifier and the purity of the ultrasonic signal output.

[0086] Figure 7(b) is the implementation circuit of the DC-5V power supply. The selected device is B0505-1WR3, which is a DC-DC power module chip. The main parameters are input voltage range 4.5V-5.5V, output voltage ±5V, and output current ±100mA. Through this chip, the 5V voltage output by the XL1509-5.0 chip can be converted into -5V voltage. The advantages of the B0505-1WR3 chip are that it has a relatively wide input voltage range, stable voltage output signal, and it requires very few peripheral devices, so this chip was selected to generate the -5V voltage.

[0087] Figure 7(c) is the implementation circuit of the DC3.3V power supply, and the main implementation chip is AMS1117-3.3. It is a linear power supply that can convert a 5V input voltage into a 3.3V output voltage. The main parameters of AMS1117-3.3 are rated output voltage 3.3V, maximum output current 1A, and output accuracy ±2%. Such output accuracy can meet the MCU's requirements for voltage stability. A relatively important point is that the price of AMS1117-3.3 is relatively low, which is very conducive to the convenience and practicality of the measurement system.

[0088] At the same time, in order to communicate between the host computer and the entire hardware system, a communication control chip is needed as a bridge to connect the USB to RS485 adapter to communicate with the MCU. The hardware block diagram of the communication unit is as follows Figure 8 As shown:

[0089] The circuit uses TD321D485H as the communication controller. This communication module has its own isolation function and has the control function of automatically identifying the data direction. It can support a communication rate of up to 500KBps. The operating voltage range is 3.0V-5.5V, and it has built-in overcurrent protection, short circuit protection and other functions. At the same time, the chip has a built-in 120 ohm resistor, which can effectively reduce the driving power consumption and crosstalk. This chip has an excellent low-power design and is suitable for application scenarios that require long-term operation. The system design and wiring are relatively simple, with only a few peripheral circuits such as resistors.

[0090] According to the analysis of DN100 304 stainless steel pipe, it is found that the characteristics of ultrasonic echo are suitable for multiple Gaussian echo model and two single Gaussian echo model. Therefore, these two models can be used to comprehensively describe the echo of ultrasonic propagation in the pipe wall.

[0091] The pipeline ultrasonic propagation echo model is a theoretical model used to describe the propagation of sound waves in a pipeline and the generation of echoes. Based on the acoustic principle and pipeline structural characteristics, the model describes the echo signal generated when sound waves propagate in a pipeline by considering the propagation path, reflection, refraction, diffraction and other phenomena of sound waves.

[0092] First, the pipeline ultrasonic propagation echo model considers the path of the sound wave propagating along the inside of the pipeline after it is emitted from the ultrasonic transducer. This includes processes such as direct sound wave propagation, multiple reflections, and refraction. Secondly, the model considers the impact of the internal structure of the pipeline on the propagation of sound waves, such as the material, thickness, surface condition of the pipe wall, and the medium state inside the pipeline.

[0093] Furthermore, the pipeline ultrasonic propagation echo model takes into account the interaction between the sound wave and the internal structure of the pipeline, including the absorption, scattering, and attenuation of the sound wave. These factors affect the energy transfer and signal strength of the sound wave in the pipeline. Finally, the model also takes into account the echo signal received by the receiver and extracts useful information through signal processing methods, such as detecting internal defects in the pipeline and measuring fluid flow rate.

[0094] Next is the process of establishing the pipeline ultrasonic model:

[0095] First, the echo of the transmitted wave reflected and transmitted multiple times on the pipe wall is represented as a Gaussian echo sequence with a center frequency of 5MHz. This sequence describes the acoustic wave signal that returns to the probe after the transmitted wave is transmitted through the inner wall of the pipe and reflected and transmitted multiple times between the inner wall of the pipe and the medium.

[0096] Next, the echo of the wave emitted from the opposite probe passing through the two layers of pipe walls and the fluid transported in the middle and reaching this probe can be represented by a single Gaussian echo with a center frequency of 5MHz, an amplitude of 0.5V, and a time width of 1μs. This echo represents the sound wave signal returned to the probe after the sound wave passes through the pipe wall and the fluid, and has a single Gaussian waveform feature.

[0097] Finally, consider that the probe transmits the wave through the pipe wall and fluid, reaches the opposite pipe wall, is reflected back to the fluid at the interface of the fluid pipe wall, and then passes through the pipe wall to receive the echo, which can be represented by a single Gaussian echo with a center frequency of 5MHz, an amplitude of 0.5V, and a time width of 2μs and added to the multiple Gaussian echo model. This echo represents the sound wave signal that returns to the probe after multiple interface reflections and transmissions, and has a longer time width, reflecting the time delay effect caused by multiple propagations and reflections.

[0098] In order to extract the time difference between the third main echo and the first main echo, the established pipeline ultrasonic model is used in Matlab to perform cross-correlation with the received ultrasonic echo signal. By analyzing the peak of the cross-correlation result, the main peak arrival time of the first ultrasonic echo can be determined, and the time difference between the third echo peak and the first main echo peak can be further calculated.

[0099] Such an improved Gaussian echo model algorithm can help accurately extract key information in the ultrasonic pipeline propagation model and provide an important basis for subsequent data processing and analysis.

[0100] The pipe diameter calculation formula of the ultrasonic echo algorithm is as follows:

[0101] D 1 =Dv×Δt

[0102] Where:

[0103] D——pipeline outer diameter, m;

[0104] D 1 ——Inner diameter of the pipe, m;

[0105] v——the velocity of ultrasonic waves in the pipe material, m / s;

[0106] Δt – the time interval from the first echo to the third echo, s.

[0107] The pipe diameter calculation formula of the proposed ultrasonic echo algorithm is used to measure the pipe diameter and obtain the pipe diameter value. In order to improve the accuracy of the measurement results, it is necessary to perform power spectrum analysis on the original signal and perform frequency domain compression operations, such as Fig.13 and Fig.14 As shown, the cross-correlation operation is performed again to solve the pipe wall thickness and pipe diameter. The result of the first echo cross-correlation signal diagram after frequency domain compression is as follows: Fig.15 The result of the third echo cross-correlation signal after frequency domain compression is shown in Fig.16 shown.

[0108] Embodiment 1, a multi-channel ultrasonic thickness measuring device.

[0109] like Figure 1 -As shown in Figure 7, the system provided by the present invention is composed of multiple ultrasonic probes, which are distributed at different positions of the measured pipeline, and can simultaneously measure the inner diameter thickness of the pipeline at different positions. The design of multiple probes can effectively reduce the measurement error, improve the measurement accuracy and reliability, and on the other hand, more cross-sectional information of the pipeline can be obtained to more accurately restore the pipeline cross section.

[0110] The whole hardware system needs three major parts to realize the excitation and echo reception of multi-channel ultrasound. The first part is the ultrasonic probe array, which contains eight ultrasonic probes, each of which is connected to the designed hardware connection part through an ultrasonic connecting line. After the probe is installed, it is fixed with a fixing device. The second part is the hardware module that needs to be designed emphatically, including an ultrasonic excitation module, an ultrasonic receiving module, a power supply module, and a communication module. Among them, the ultrasonic excitation module and the ultrasonic receiving module are the parts directly connected to the ultrasonic probe, which are responsible for the excitation of the ultrasonic wave and the reception of the echo. Another part of the ultrasonic receiving module is connected to the data acquisition card, which is used to send the ultrasonic echo signal to the data acquisition card. The power supply module is connected to the power supply from 220V AC to convert it into the voltage required by the hardware module. The communication module is responsible for the communication between the host and the hardware module, which is used to monitor the working status of the whole hardware system and control the whole hardware module to perform the preset working mode. The third part is the data processing module, which mainly contains a data acquisition card and is connected to the host through a connecting line. The main work of this part is to collect the waveform of the ultrasonic echo signal and store it for analysis to obtain the time difference of the ultrasonic echo.

[0111] Example 2, a method for measuring the inner diameter of a pipeline using ultrasonic technology

[0112] As shown in FIG. 7 , the method for measuring the inner diameter of a pipeline provided by the present invention is as follows: each ultrasonic probe is perpendicular to the pipe wall, so that the ultrasonic signal emitted by the ultrasonic probe is received by the opposite ultrasonic probe, and the echo signal is reflected back and received by the ultrasonic probe that initially emitted the signal. Therefore, the connection line between each pair of opposing ultrasonic probes is at a 90° angle to the pipe wall, and the connection line between each pair of ultrasonic probes passes through the center of the cross section. The STM32F407ZET6 single-chip microcomputer and communication module are used to control the reception and emission of four ultrasonic signals. Since the ultrasonic wave propagates at a certain speed in the pipe wall, the time interval between the primary reflected wave, the secondary reflected wave and the emitted wave is used to measure the inner diameter of the pipeline, and then the cross-sectional area is calculated.

[0113] The pipe diameter calculation formula of the ultrasonic echo algorithm is as follows:

[0114] D 1 =Dv×Δt

[0115] Where:

[0116] D——pipeline outer diameter, m;

[0117] D 1 ——Inner diameter of the pipe, m;

[0118] v——the velocity of ultrasonic waves in the pipe material, m / s;

[0119] Δt – the time interval from the first echo to the third echo, s.

[0120] In order to process the ultrasonic echo data more accurately, an improved adaptive Gaussian echo cross-correlation algorithm is used. Through this algorithm, the waveform of the ultrasonic echo can be analyzed and processed more accurately, and the time difference between the reflected waves of the first main multiple Gaussian ultrasonic echo and the transit time of the first main multiple Gaussian ultrasonic echo and the third main Gaussian ultrasonic echo can be better calculated.

[0121] Taking the DN100 pipe echo data as an example, preset Fig.11 The Gaussian echo signal shown in the figure. The specific parameters of this signal are: 5MHz carrier frequency, 4 pulse cycles, 50μm echo arrival time, and the echo signal is cross-correlated with the preset Gaussian echo signal. The result is as follows Fig.12 shown.

[0122] Perform power spectrum analysis on the original cross-correlation signal. The power spectrum contains the different power values ​​of each frequency component of the function. The power is calculated for each frequency point and finally plotted as a power spectrum function. The calculation formula of the power spectrum is as follows:

[0123]

[0124] Where:

[0125] N is the length of the discrete signal,

[0126] f k ——the frequency of the kth frequency point,

[0127] x(n) is the amplitude of the sampled signal at the nth moment.

[0128] The power spectrum after frequency domain compression is as follows Fig.13 As shown in the figure, the power frequency range of the signal is less than 10MHz. Therefore, the power spectrum part with a frequency higher than 10MHz is removed. At the same time, the power spectrum function of the useful signal is downsampled by 10 times, and the downsampled spectrum part is transferred to around 5MHz to achieve spectrum compression and enhancement of the 5MHz frequency.

[0129] The advantage of the correlation signal after frequency domain compression is that the peak discrimination of the compressed cross-correlation signal is higher than that of the original cross-correlation function. In the cross-correlation part representing the first main multiple Gaussian echo of the original signal, the peak is more obvious, and the time difference of the multiple echo signals is more obvious. The time difference of the multiple echo signals can be calculated more accurately, which is beneficial to improve the measurement accuracy of the pipe wall thickness. Fig.14 This is the cross-correlation signal diagram after frequency domain compression.

[0130] go through Fig.14 and Fig.12 By comparison, it can be seen that the peak discrimination of the compressed cross-correlation signal is higher than that of the original cross-correlation function. In the cross-correlation part representing the first main multiple Gaussian echo of the original signal, the peak is more obvious, and the time difference of multiple echo signals is more obvious. The time difference of multiple echo signals can be calculated more accurately, and the measurement accuracy of pipe wall thickness is improved.

[0131] The proposed ultrasonic echo algorithm combines the measurement of pipe diameter and signal processing techniques to improve the accuracy of the measurement results. First, the ultrasonic signal propagating in the pipe is used to extract the initial estimate of the pipe diameter based on its characteristics. Then, to further improve the accuracy, the original signal is subjected to power spectrum analysis to understand the characteristics of the signal in the frequency domain. Then, the signal is processed through a frequency domain compression operation to highlight the important features. This step helps to reduce the impact of noise on the measurement results and improves the accuracy and reliability of the measurement.

[0132] Next, the processed signals are cross-correlated again to further determine the precise values ​​of the pipe wall thickness and pipe diameter. This step allows for a more accurate calculation of the pipe diameter and a deeper understanding of the pipe’s structural characteristics.

[0133] The innovation of the whole algorithm lies in the combination of ultrasonic measurement technology and signal processing technology, which uses information in the frequency domain to improve the accuracy of the measurement results. By performing power spectrum analysis and frequency domain compression operations on the original signal, the influence of noise can be effectively reduced, and the accuracy and stability of the measurement can be improved. At the same time, by performing cross-correlation operations again, the diameter of the pipeline can be determined more accurately, providing an important basis for pipeline inspection and maintenance.

[0134] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-channel ultrasonic thickness measurement method, characterized in that: The method comprises: Acquiring ultrasonic echo data; An improved adaptive Gaussian echo cross-correlation algorithm is used to analyze and process the waveform of the ultrasonic echo, and the time difference between the reflected waves of the first main multiple Gaussian ultrasonic echo and the transit time difference between the third Gaussian echo peak and the first main Gaussian echo peak are obtained; The pipeline diameter is measured by using the pipeline diameter calculation formula of the ultrasonic echo algorithm to obtain the pipeline diameter value; The pipe diameter calculation formula of the ultrasonic echo algorithm is: D1=Dv×Δt Where: D——pipeline outer diameter, m; D1——inner diameter of the pipe, m; v——the velocity of ultrasonic waves in the pipe material, m / s; Δt – the time interval from the first echo to the third echo, s; The improved adaptive Gaussian echo cross-correlation algorithm is specifically: The preset Gaussian echo signal is used to perform cross-correlation with the received Gaussian echo signal to calculate multiple cross-correlation peaks. The cross-correlation signal is subjected to power spectrum analysis by frequency domain compression. The power spectrum contains the different power values ​​of each frequency component of the function. The power is calculated for each frequency point and finally plotted as a power spectrum function.

2. The multi-channel ultrasonic thickness measurement method according to claim 1, characterized in that: The calculation formula of the power spectrum is as follows: Where: N is the length of the discrete signal, f k ——the frequency of the kth frequency point, x(n) is the amplitude of the sampled signal at the nth moment.

3. A multi-channel ultrasonic thickness measuring device, used for applying the multi-channel ultrasonic thickness measuring method according to any one of claims 1 to 2, characterized in that: The device comprises: An ultrasonic probe array, used for receiving and generating ultrasonic signals; Ultrasonic hardware module, used to process the echo signal sent by the ultrasonic sensor, The data processing module includes a data acquisition card, which is used to collect and store the waveform of the ultrasonic echo signal and provide data support; The ultrasonic probe array includes 8 ultrasonic probes; The ultrasonic hardware module includes an ultrasonic excitation module, an ultrasonic receiving module, a power supply module, and a communication module; The ultrasonic excitation module is used to generate and send ultrasonic signals; The ultrasonic receiving module is used to receive and process the echo signal sent by the ultrasonic sensor, and send the ultrasonic echo signal to the data acquisition card; The power supply module is used to convert 220V AC power into the required voltage; The communication module is used for the communication between the host computer and the ultrasonic hardware module, monitoring the system status and controlling the working mode; The ultrasonic excitation module and the ultrasonic receiving module are directly connected to the ultrasonic probe array.

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