Ultrasonic-based gas flow rate measurement method, apparatus, system, and electronic device

Abstract

The application relates to the technical field of gas measurement, and discloses a gas flow velocity measurement method, device and system based on ultrasonic waves and electronic equipment, the method comprising the following steps: acquiring an uplink waveform signal and a downlink waveform signal; performing differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain a time-of-flight difference between the uplink waveform signal and the downlink waveform signal; acquiring a current temperature and a current pressure; determining the reliability of the time-of-flight difference based on multiple quality evaluation indexes, the multiple quality evaluation indexes comprising at least two of a signal-to-noise ratio, a peak-to-noise ratio, a deviation value of the time-of-flight difference and a historical time-of-flight difference and a correlation peak width; when the reliability is greater than a first preset threshold, compensating the time-of-flight difference based on the current temperature and the current pressure to obtain a compensated time-of-flight difference; and determining the flow velocity of the gas to be measured based on the compensated time-of-flight difference and a first distance. The application can eliminate inherent delays of the system and reduce the dependence on frequent calibration.

Description

Technical Field

[0001] This invention relates to the field of semiconductor testing technology, and more specifically to a method, apparatus, system, and electronic device for measuring gas flow rate based on ultrasound. Background Technology

[0002] When processing wafers using equipment such as Metal-Organic Chemical Vapor Deposition (MOCVD), it is necessary to accurately detect parameters such as the gas flow rate and volume concentration entering the reaction chamber in order to ensure processing accuracy.

[0003] In related technologies, the zero-crossing detection method or the direct cross-correlation method is used to determine the time of flight (ToF) of ultrasound in a gas, and then parameters such as gas flow rate are calculated based on the time of flight. The zero-crossing detection method uses a time-to-digital converter (TDC) to detect the time of zero crossing of the received signal and calculates the time interval (i.e., time of flight) between the transmitted and received signals. The direct cross-correlation method directly performs cross-correlation calculations on the transmitted and received signals and determines the time of flight by the position of the correlation peak.

[0004] The methods described above are sensitive to the inherent delays of the measuring device (such as circuit delays and sensor response time delays). If calibration is not frequent, the accuracy of the measured time of flight may be low; if calibration is frequent, the measurement time is extended, increasing maintenance costs. Moreover, the zero-crossing method is limited by clock frequency and signal quality, making it difficult to achieve nanosecond-level accuracy. Although the direct cross-correlation method can theoretically achieve higher accuracy, it is limited by sampling rate and calculation accuracy, and is affected by environmental factors, resulting in lower reliability of measurement accuracy. Summary of the Invention

[0005] This invention provides a method, apparatus, system, and electronic device for measuring gas flow velocity based on ultrasound, in order to solve the problems of low gas measurement accuracy and the need for frequent calibration.

[0006] In a first aspect, the present invention provides a gas flow velocity measurement method based on ultrasound, the method comprising: acquiring an uplink waveform signal and a downlink waveform signal, wherein the uplink waveform signal is an ultrasonic pulse signal received by a second transceiver from a first transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first transceiver from a second transceiver, the first transceiver and the second transceiver being positioned relative to each other along the propagation direction of the gas to be measured; performing differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal; and acquiring the current temperature and the current pressure, wherein the current temperature is the uplink waveform signal. The waveform signal corresponds to the temperature of the gas under test at the current time, and the current pressure is the pressure of the gas under test at the current time corresponding to the uplink waveform signal. Based on multiple quality evaluation indicators, the reliability of the time-of-flight difference is determined. These multiple quality evaluation indicators include at least two of the following: signal-to-noise ratio, peak-to-noise ratio, deviation of the time-of-flight difference from historical time-of-flight differences, and relevant peak width. When the reliability is greater than a first preset threshold, the time-of-flight difference is compensated based on the current temperature and current pressure to obtain the compensated time-of-flight difference. Based on the compensated time-of-flight difference and a first distance, the flow velocity of the gas under test is determined. The first distance is the distance between the first transceiver and the second transceiver in the direction of gas propagation.

[0007] In one optional implementation, differential cross-correlation processing is performed on the uplink and downlink waveform signals to obtain the time-of-flight difference between them. This includes: determining the cross-correlation function of the uplink and downlink waveform signals based on Fourier transform; determining the initial sampling point corresponding to the initial maximum peak value from the cross-correlation function; performing cubic spline interpolation on the correlation between the initial maximum peak value and multiple sampling points adjacent to the initial sampling point to obtain an interpolation curve; and determining the time-of-flight difference based on the target sampling point corresponding to the target maximum value determined from the interpolation curve.

[0008] In one optional implementation, before performing differential cross-correlation processing on the uplink and downlink waveform signals, the method further includes: filtering the uplink waveform signal and filtering the downlink waveform signal; determining the cross-correlation function of the uplink and downlink waveform signals based on Fourier transform, including: determining the cross-correlation function of the filtered uplink waveform signal and the filtered downlink waveform signal based on Fourier transform.

[0009] In one optional implementation, the compensated flight time difference is obtained based on the current temperature and current pressure, including: inputting the current temperature and current pressure into the compensation model, determining the deviation amount according to the output of the compensation model, wherein the compensation model is used to characterize the measurement error caused by temperature and pressure changes; and determining the difference between the flight time difference and the deviation amount as the compensated flight time difference.

[0010] In one alternative implementation, the expression for the compensation model is:

[0011] In the formula, Indicates the deviation amount. Indicates the temperature compensation coefficient. Indicates the current temperature. Indicates reference temperature. Indicates the pressure compensation coefficient. Indicates current pressure. Indicates reference pressure. This indicates a fixed offset.

[0012] In one alternative implementation, the reliability of the flight time difference is determined based on multiple quality evaluation indicators, including: determining a quality score based on the quality evaluation indicators using the following formula:

[0013] In the formula, Indicates quality score, The weights represent the signal-to-noise ratio. This represents the score corresponding to the signal-to-noise ratio. The weights corresponding to the peak-to-noise ratio are: This represents the score corresponding to the peak-to-noise ratio. This indicates the weight corresponding to the width of the relevant peak. This represents the score corresponding to the width of the relevant peak. The weights corresponding to the deviations between the flight time difference and historical flight time differences. This represents the score corresponding to the deviation between the flight time difference and the historical flight time difference; based on the quality score, the reliability of the flight time difference is determined.

[0014] In an optional implementation, the method further includes: when the reliability is less than or equal to a first preset threshold and greater than a second preset threshold, marking the time-of-flight difference and redetermining the time-of-flight difference, wherein the second preset threshold is less than or equal to the first preset threshold; when the reliability is less than or equal to the second preset threshold, removing the time-of-flight difference and redetermining the time-of-flight difference after adjusting the transmission power of the ultrasonic pulse signal.

[0015] In one optional implementation, the method further includes: triggering an early warning signal if the reliability of a consecutive preset number is less than or equal to a second preset threshold.

[0016] In an optional implementation, the method further includes: determining the uplink flight time based on the uplink waveform signal when the reliability is greater than a first preset threshold; compensating the uplink flight time based on the current temperature and current pressure to obtain a compensated uplink flight time; determining the downlink flight time based on the downlink waveform signal when the reliability is greater than the first preset threshold; compensating the downlink flight time based on the current temperature and current pressure to obtain a compensated downlink flight time; determining the sound velocity of the gas to be measured based on the compensated uplink flight time, the compensated downlink flight time, and a first distance; and determining the volume concentration of the gas to be measured based on the sound velocity of the gas to be measured and the correspondence between sound velocity and volume concentration.

[0017] Secondly, the present invention provides an ultrasonic-based gas flow velocity measurement device, comprising: a first acquisition module for acquiring an upward waveform signal and a downward waveform signal, wherein the upward waveform signal is an ultrasonic pulse signal received by a second transceiver from a first transceiver, and the downward waveform signal is an ultrasonic pulse signal received by the first transceiver from a second transceiver, the first transceiver and the second transceiver being arranged opposite to each other along the propagation direction of the gas to be measured; a differential processing module for performing differential cross-correlation processing on the upward waveform signal and the downward waveform signal to obtain the time-of-flight difference between the upward waveform signal and the downward waveform signal; and a second acquisition module for acquiring the current temperature and the current pressure, wherein the current temperature is the upward waveform signal. The signal corresponds to the temperature of the gas under test at the given time, and the current pressure is the pressure of the gas under test at the given time corresponding to the uplink waveform signal. A reliability determination module is used to determine the reliability of the time-of-flight difference (TOF) based on multiple quality evaluation indicators, including at least two of the following: signal-to-noise ratio, peak-to-noise ratio, deviation of the time-of-flight difference from historical time-of-flight differences, and relevant peak width. An environmental compensation module is used to compensate for the TOF based on the current temperature and current pressure when the reliability exceeds a first preset threshold, obtaining the compensated TOF. A flow rate determination module is used to determine the flow rate of the gas under test based on the compensated TOF and a first distance, where the first distance is the distance between the first and second transceivers in the direction of gas propagation.

[0018] Thirdly, the present invention provides an ultrasonic-based gas flow velocity measurement system, comprising: a first transceiver for transmitting ultrasonic pulse signals to and receiving ultrasonic pulse signals from a second transceiver, wherein the first and second transceivers are arranged opposite to each other along the propagation direction of the gas to be measured; a second transceiver for transmitting ultrasonic pulse signals to and receiving ultrasonic pulse signals from the first transceiver; an environmental sensor for detecting the temperature and pressure of the gas to be measured; and a signal processor connected to the first transceiver, the second transceiver, and the environmental sensor for acquiring an uplink waveform signal and a downlink waveform signal, wherein the uplink waveform signal is the ultrasonic pulse signal received by the second transceiver from the first transceiver, and the downlink waveform signal is the ultrasonic pulse signal received by the first transceiver from the second transceiver; the signal processor is further configured to process the uplink and downlink waveform signals. The waveform signal undergoes differential cross-correlation processing to obtain the time-of-flight difference between the uplink and downlink waveform signals. The signal processor is also used to acquire the current temperature and current pressure, where the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal. The signal processor is also used to determine the reliability of the time-of-flight difference based on multiple quality evaluation indicators, including at least two of the following: signal-to-noise ratio, peak-to-noise ratio, deviation between the time-of-flight difference and historical time-of-flight differences, and relevant peak width. The signal processor is also used to compensate for the time-of-flight difference based on the current temperature and current pressure when the reliability is greater than a first preset threshold, obtaining a compensated time-of-flight difference. The signal processor is also used to determine the flow velocity of the gas to be measured based on the compensated time-of-flight difference and a first distance, where the first distance is the distance between the first and second transceivers in the direction of gas propagation.

[0019] In one alternative implementation, the system further includes a communication and display, which is connected to a signal processor for displaying the compensated time-of-flight difference and the flow rate of the gas being measured.

[0020] Fourthly, the present invention provides an electronic device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the ultrasonic-based gas flow rate measurement method of the first aspect or any corresponding embodiment described above.

[0021] Fifthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the ultrasonic-based gas flow rate measurement method of the first aspect or any corresponding embodiment described above.

[0022] In a sixth aspect, the present invention provides a computer program product, including computer instructions for causing a computer to execute the ultrasonic-based gas flow rate measurement method of the first aspect or any corresponding embodiment described above.

[0023] The ultrasonic-based gas flow velocity measurement method, device, system, electronic device, and storage medium provided by this invention have at least the following advantages: Determining gas flow rate by measuring the time difference between the uplink and downlink waveform signals can offset the inherent delay of the measurement system, reduce calibration requirements, and allow for accurate gas flow rate measurement even with infrequent calibration. Furthermore, the calibration interval can be extended from monthly to annually, reducing maintenance costs by 80%.

[0024] By quantitatively evaluating the reliability of each flight time measurement, calculations are only continued after the quality meets the standard (reliability is greater than the first preset threshold). This can prevent abnormal flight time differences from entering the flow rate calculation stage from the source, thereby improving the reliability of the measurement.

[0025] After the quality standard is met, the flight time difference can be compensated by the current temperature and pressure. This can eliminate the influence of environmental factors such as temperature and pressure on the flight time difference, improve the measurement stability and accuracy of the measurement system under different working conditions, and extend the applicable working temperature range of the measurement system from 0℃-50℃ to -20℃-70℃, meet the measurement needs of high-precision scenarios such as semiconductor manufacturing, and also adapt to the high temperature, high humidity and vibration environment of industrial sites.

[0026] Determining the cross-correlation function between the uplink and downlink waveform signals using Fourier transform can reduce computational complexity and thus improve computational efficiency.

[0027] By processing the sampling points through cubic spline interpolation, a time resolution exceeding the sampling rate limit can be achieved. This allows for a more accurate determination of the time delay corresponding to the maximum value point in the discrete sequence of the cross-correlation function, thus improving the accuracy of using the time delay as the time difference of flight. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a structural block diagram of a gas flow velocity measurement system based on ultrasound according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a gas flow velocity measurement method based on ultrasound according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the uplink waveform signal (uplink signal) and the downlink waveform signal (downlink signal) according to an embodiment of the present invention; Figure 4 This is a schematic flowchart of another ultrasonic-based gas flow velocity measurement method according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the cross-correlation function according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the locally magnified curve and interpolation curve of the cross-correlation function according to an embodiment of the present invention; Figure 7 This is a schematic flowchart of another ultrasonic-based gas flow velocity measurement method according to an embodiment of the present invention; Figure 8 This is a structural block diagram of a gas flow rate measuring device based on ultrasound according to an embodiment of the present invention; Figure 9 This is a structural block diagram of another ultrasonic-based gas flow velocity measurement system according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] The ultrasonic-based gas velocity measurement method provided by this invention relies on an ultrasonic-based gas velocity measurement system. As an optional application scenario of this invention, such as... Figure 1As shown, the ultrasonic-based gas flow rate measurement system may include a first transceiver 110, a second transceiver 120, a signal processor 130, and an environmental sensor 140. The first transceiver 110 and the second transceiver 120 are arranged opposite to each other along the propagation direction of the gas to be measured. The first transceiver 110 is used to transmit ultrasonic pulse signals to the second transceiver 120 and receive ultrasonic pulse signals from the second transceiver 120. The second transceiver 120 is used to send ultrasonic pulse signals to the first transceiver 110 and receive ultrasonic pulse signals from the first transceiver 110.

[0033] For example, the first transceiver 110 and the second transceiver 120 can be disposed opposite to each other on the inner wall of the transmission pipeline 200 for the gas to be measured, and the environmental sensor 140 is disposed inside the transmission pipeline 200 for detecting environmental information such as temperature, pressure and humidity. The first transceiver 110, the second transceiver 120 and the environmental sensor 140 can be connected to the signal processor 130 via a network.

[0034] Specifically, the signal processor 130 can be a smartphone, tablet, laptop, PDA, desktop computer, smart wearable device, etc. The network can be a wired network or a wireless network, and examples include, but are not limited to, the Internet, corporate intranet, local area network, wide area network, mobile communication network, and combinations thereof.

[0035] Optionally, the environmental sensor 140 may include sensors such as a temperature sensor, a pressure sensor, and a humidity sensor.

[0036] The ultrasonic-based gas velocity measurement method, device, and electronic equipment provided by this invention accurately measure the minute time difference (time-of-flight difference) of ultrasonic wave propagation in two directions by cross-correlation of the uplink and downlink waveform signals, achieving sub-nanosecond or even picosecond level time measurement accuracy. Moreover, the inherent delay of the measurement device can be eliminated by the time difference, reducing the dependence on frequent calibration and improving long-term stability. By compensating for the time difference, the influence of environmental factors can be eliminated, maintaining stable performance over a wide range of temperature, pressure, and gas composition.

[0037] According to an embodiment of the present invention, an embodiment of a gas flow velocity measurement method based on ultrasound is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although in the flowchart... Figure 2 The logical order is shown, but in some cases, the steps shown or described may be performed in a different order than that shown here.

[0038] This embodiment provides a gas flow velocity measurement method based on ultrasound, which can be used in the signal processor 130 described above. Figure 2 This is a schematic flowchart of a gas flow velocity measurement method based on ultrasound according to an embodiment of the present invention, as shown below. Figure 2 As shown, the process includes the following steps: Step S201: Obtain the uplink waveform signal and the downlink waveform signal.

[0039] The uplink waveform signal is the ultrasonic pulse signal received by the second transceiver 120 from the first transceiver, and the downlink waveform signal is the ultrasonic pulse signal received by the first transceiver 110 from the second transceiver.

[0040] The signal processor 130 acquires an uplink waveform signal from the second transceiver 120 and a downlink waveform signal from the first transceiver 110. The first transceiver 110 includes a first ultrasonic sensor and a first analog-to-digital converter. The second transceiver 120 includes a second ultrasonic sensor and a second analog-to-digital converter. Both the first ultrasonic sensor and the second ultrasonic sensor can transmit and receive ultrasonic pulse signals.

[0041] The second analog-to-digital converter samples the ultrasonic pulse signal received by the second ultrasonic sensor from the first ultrasonic sensor, and the first analog-to-digital converter samples the ultrasonic pulse signal received by the first ultrasonic sensor from the second ultrasonic sensor. Therefore, both the uplink and downlink waveform signals can be discrete digital signals.

[0042] Step S202: Perform differential cross-correlation processing on the uplink and downlink waveform signals to obtain the time difference between the uplink and downlink waveform signals.

[0043] For example, the uplink waveform signal and the downlink waveform signal can be as follows: Figure 3 As shown, from Figure 3 It can be seen that the uplink and downlink waveform signals are highly similar. Both the uplink and downlink waveform signals are sinusoidal signals obtained after the ultrasonic pulse signal propagates through the gas in the pipe, but they are in different directions. The uplink and downlink waveform signals have a certain time delay on the time axis, and this time delay is the time difference between the uplink and downlink waveform signals.

[0044] Specifically, after acquiring the uplink and downlink waveform signals, the uplink waveform signal and the downlink waveform signal can be differentially processed first. Then, the correlation value (degree of correlation) between the differentially processed uplink and downlink waveform signals can be characterized by the cross-correlation function. When the cross-correlation function reaches its maximum value, the time corresponding to the maximum value is the time difference of flight.

[0045] Step S203: Obtain the current temperature and current pressure.

[0046] Wherein, the current temperature is the temperature of the gas to be measured at the corresponding moment of the upward waveform signal, and the current pressure is the pressure of the gas to be measured at the corresponding moment of the upward waveform signal.

[0047] The environmental sensor 140 includes a temperature sensor for detecting the temperature of the gas to be measured and a pressure sensor for detecting the pressure of the gas to be measured. During the measurement process, the temperature sensor detects the temperature of the gas to be measured in real time, and the pressure sensor detects the pressure of the gas to be measured in real time. The signal processor can obtain the current temperature from the temperature sensor and the current pressure from the pressure sensor.

[0048] Step S204: Determine the reliability of the flight time difference based on multiple quality evaluation indicators.

[0049] Among them, several quality evaluation indicators include at least two of the following: signal-to-noise ratio, peak-to-noise ratio, time-of-flight difference, deviation of historical time-of-flight difference, and relevant peak width. The reliability of the time-of-flight difference can determine whether it is usable.

[0050] Specifically, signal-to-noise ratio , The root mean square (RMS) value represents the effective portion of the received signal (uplink or downlink waveform), indicating the signal's energy level. The root mean square value of noise represents the energy level of the noise. It can be estimated based on the signal in the silent zone (without effective signal, only noise) before the transmitted signal (first transmitted signal or second transmitted signal).

[0051] Peak-to-noise ratio , This represents the peak height of the main peak of the cross-correlation function. This represents the noise floor mean near the main peak of the cross-correlation function. Taking the maximum value of the cross-correlation function curve yields the peak height of the main peak. Excluding the main peak and its vicinity (±5 sampling points), the average absolute value of the curve portions on either side of the main peak can be used to determine the noise floor mean. A larger PNR indicates a more prominent main peak and less interference from spurious peaks.

[0052] After determining the main peak of the cross-correlation function, determine the half-power point of the main peak (i.e., the peak height). Then, determine the sampling point position corresponding to the half-power point on each side of the main peak, and determine the distance between the two sampling points as the correlation peak width (main lobe width). The narrower the width, the better the signal focusing and the higher the positioning accuracy.

[0053] The deviation between the flight time difference and historical flight time differences can refer to the deviation between the flight time difference and the historical median value, which is the average of multiple historical flight time differences. The number of historical flight time differences can range from 5 to 10. A smaller deviation between the flight time difference and historical flight time differences indicates better consistency. For gases with gradual changes in flow rate or volumetric concentration, consistency is an important quality indicator.

[0054] Signal-to-noise ratio (SNR) reflects the degree to which ultrasonic pulse signals are affected by environmental noise and electromagnetic interference. Peak-to-noise ratio (PNR) can determine whether the echo peak is unique and whether the waveform is regular. A poor PNR indicates strong clutter interference. The correlation peak width reflects the degree of temporal dispersion of the uplink and downlink waveform signals. The wider the correlation peak width, the more severe the signal dispersion. The deviation between the time-of-flight difference and the historical time-of-flight difference reflects the continuity of data timing. Under normal operating conditions, the gas flow rate will not change abruptly in a short period of time, and the corresponding time-of-flight difference should change continuously and gradually.

[0055] Gas media are susceptible to turbulence, noise, temperature and pressure disturbances, pipeline impurities, and electromagnetic interference, which may cause distortion of ultrasonic echo waveforms and misjudgment of peak values, resulting in inaccurate time-of-flight differences (TOF). By jointly verifying at least two quality evaluation indicators, the reliability level of TOF can be quantified, and valid normal data, weakly interfering data, and severely abnormal data can be distinguished. This enables outlier removal, data weighting correction, and measurement status alarms, preventing abnormal TOF from entering the flow velocity calculation stage from the source. This provides reliable data for subsequent temperature and pressure compensation, improving the accuracy, stability, and robustness of the measurement system.

[0056] Specifically, the quality score of the flight time difference can be determined first based on multiple quality evaluation indicators. Then, the reliability of the flight time difference can be characterized by the quality score. The quality score is directly proportional to the reliability. The higher the quality score, the higher the reliability, indicating that the accuracy of the flight time difference is higher.

[0057] Step S205: When the reliability is greater than the first preset threshold, the flight time difference is compensated based on the current temperature and current pressure to obtain the compensated flight time difference.

[0058] The first preset threshold is a critical threshold for determining the reliability of the time difference of flight (TDF), and can be determined based on historical data. For example, if the reliability range is [0,1], the first preset threshold can be 0.6. When the reliability is greater than 0.6, it indicates that the calculated TDF is reliable.

[0059] Specifically, changes in temperature and / or pressure within the transmission pipeline affect the properties of the gas medium and the propagation speed of ultrasound, potentially causing a shift in the time-of-flight difference. Compensating for the time-of-flight difference based on the current temperature and pressure can correct deviations caused by sound speed drift and medium attenuation, thereby eliminating the influence of environmental factors such as temperature and pressure and restoring the true time-of-flight difference.

[0060] For example, based on the established correspondence between temperature, pressure, and time deviations, the current time deviation corresponding to the current temperature and pressure can be determined, and then the flight time difference can be compensated based on the current time deviation. The current time deviation can be positive or negative, and the compensated flight time difference is the sum of the current time deviation and the flight time difference.

[0061] Step S206: Determine the flow rate of the gas to be measured based on the compensated time difference and the first distance.

[0062] Wherein, the first distance is the distance L between the first signal transceiver 110 and the second signal transceiver 120 in the direction of gas propagation.

[0063] Specifically, based on the principle of ultrasonic gas flow measurement, when the first distance is known, the flow velocity of the gas to be measured can be determined by the following formula (1):

[0064] In the formula, This indicates the flow rate of the gas being measured. Indicates the first distance. This indicates the uplink flight time after compensation based on the current pressure and temperature. This indicates the downlink flight time after compensation based on the current pressure and temperature. The difference in flight time after compensation is indicated. The uplink flight time refers to the time it takes for the ultrasonic pulse signal to travel from the first signal processor to the second signal processor in the gas under test, which is determined by the ultrasonic pulse signal emitted by the first ultrasonic sensor (denoted as the first transmitted signal) and the uplink waveform signal. The downlink flight time refers to the time it takes for the ultrasonic pulse signal to travel from the second signal processor to the first signal processor in the gas under test, which is determined by the ultrasonic pulse signal emitted by the second ultrasonic sensor (denoted as the second transmitted signal) and the downlink waveform signal.

[0065] The ultrasonic-based gas flow velocity measurement method provided in this embodiment acquires the uplink and downlink waveform signals, performs differential cross-correlation processing on the uplink and downlink waveform signals to obtain the time-of-flight difference between them, then determines the reliability of the time-of-flight difference based on multiple quality evaluation indicators, and when the reliability is greater than a first preset threshold, compensates for the time-of-flight difference based on the acquired current temperature and current pressure, and determines the flow velocity of the gas to be measured based on the compensated time-of-flight difference and a first distance.

[0066] This invention determines gas flow rate by utilizing the time-of-flight difference between uplink and downlink waveform signals. Compared to directly calculating using echo signals, this eliminates the inherent delay shared by both signals, reducing calibration requirements and allowing for gas flow rate measurement without frequent calibrations. The calibration interval can be extended from monthly to annually, reducing maintenance costs by 80%. Furthermore, after obtaining the time-of-flight difference, this invention does not directly determine the gas flow rate based on it. Instead, it calculates the flow rate only after confirming the reliability of the time-of-flight difference (its reliability exceeds a first preset threshold) and compensating for it. This not only prevents abnormal time-of-flight differences from entering the flow rate calculation process, providing reliable data for subsequent temperature and pressure compensation, but also eliminates the influence of environmental factors such as temperature and pressure, improving the measurement accuracy, stability, and robustness of the measurement system.

[0067] This embodiment provides another ultrasonic-based gas flow rate measurement method, which can be used in the signal processor 130 described above. Figure 4 This is a schematic flowchart of another ultrasonic-based gas flow velocity measurement method according to an embodiment of the present invention, as shown below. Figure 4 As shown, the process includes the following steps: Step S401: Obtain the uplink waveform signal and the downlink waveform signal.

[0068] Please see details Figure 2 Step S201 of the illustrated embodiment will not be described again here.

[0069] Step S402: Perform differential cross-correlation processing on the uplink and downlink waveform signals to obtain the time difference between the uplink and downlink waveform signals.

[0070] Specifically, step S402 above may include: Step S4021: Based on Fourier transform, determine the cross-correlation function of the uplink and downlink waveform signals.

[0071] The uplink and downlink waveform signals are discrete digital signals, and the cross-correlation function can be defined as shown in formula (2):

[0072] In the formula, Indicates the upward waveform signal and downlink waveform signal The degree of correlation at different time shifts For data sequence number, for and The number of data shifts between them , The number of sampling points. , This indicates the number of sampling points for the uplink waveform signal. This indicates the number of sampling points for the downlink waveform signal. This indicates the length of the cross-correlation sequence.

[0073] According to equation (2), performing the cross-correlation function operation at point M in the time domain requires M... 2 Multiplication operation and M 2 The computational complexity of M addition operations is relatively large. Therefore, the uplink and downlink waveform signals are transformed from the time domain to the frequency domain based on the Fast Fourier Transform (FFT). Cross-correlation processing is performed in the frequency domain, and then the cross-correlation function in the frequency domain is subjected to inverse Fourier transform to obtain the cross-correlation function in the time domain.

[0074] This embodiment uses Fourier transform, which can accelerate the calculation of the cross-correlation function between the uplink and downlink waveform signals.

[0075] In some optional embodiments, before performing differential cross-correlation processing on the uplink and downlink waveform signals, the method further includes: filtering the uplink waveform signal and filtering the downlink waveform signal; in this case, step S4021 specifically involves: determining the cross-correlation function of the filtered uplink waveform signal and the filtered downlink waveform signal based on Fourier transform.

[0076] Specifically, bandpass filtering can be applied to both the uplink and downlink waveform signals. The center frequency of the filter's passband is set to the nominal frequency of the ultrasonic sensor (e.g., 200kHz), and the bandwidth is ±20% of the nominal frequency. A fourth-order Butterworth IIR bandpass filter is used, with zero-phase filtering (filtfilt) to avoid phase distortion.

[0077] Step S4022: Determine the initial sampling point corresponding to the initial maximum peak value from the cross-correlation function.

[0078] Specifically, the global maximum value (initial maximum peak value) is found in the cross-correlation function, and the time offset corresponding to the maximum value (the time corresponding to the initial sampling point) is the initial time-of-flight difference. To improve robustness, the cross-correlation function can be smoothed or the search range can be limited beforehand.

[0079] For example, physically, the time-of-flight difference is defined as the downlink delay relative to the uplink delay; therefore, the positive delay portion of the cross-correlation function is truncated (see [link to relevant documentation]). Figure 5 The maximum value is found from the truncated cross-correlation function, thus shortening the determination time.

[0080] Step S4023: Perform cubic spline interpolation on the initial maximum peak value and the correlation values ​​corresponding to multiple sampling points adjacent to the initial sampling point to obtain the interpolation curve.

[0081] The cross-correlation function calculated above is actually a discrete cross-correlation function sequence. Since the maximum value point of the discrete output of the cross-correlation function (initial maximum peak value) does not necessarily coincide with the maximum value point of the continuous output of the cross-correlation function, there is a slight deviation in the time delay between the two. If the time delay corresponding to the maximum value point of the discrete cross-correlation function sequence is directly used as the flight time difference, a certain degree of measurement error may occur.

[0082] To improve the accuracy of the time-of-flight difference (TOF), a cubic spline interpolation function is used to fit the correlation values ​​(multiple discrete points) corresponding to multiple sampling points adjacent to the initial maximum peak value, obtaining a continuous output of the cross-correlation function (interpolation curve). The cross-correlation function and interpolation curve can be represented as follows: Figure 6 As shown.

[0083] To control the computational load of the signal processor, cubic spline interpolation is only performed on critical parts. For example, taking the initial maximum peak value as the center, the correlation values ​​corresponding to two sampling points before and after the initial sampling point are taken (a total of 5 correlation value points). The cubic spline interpolation function is used to fit the selected 5 correlation value points to obtain the interpolation curve. The interpolation factor can be 1000 times.

[0084] Step S4024: Determine the flight time difference based on the target sampling time corresponding to the target maximum value determined from the interpolation curve.

[0085] Specifically, the maximum value point (target maximum value) is found from the interpolation curve, and the target sampling point corresponding to the maximum value point is obtained. Then, the time difference is determined by subtracting the reference offset from the target sampling point and dividing by the sampling rate. Here, the reference offset can be the center offset of the cross-correlation function.

[0086] Step S403: Obtain the current temperature and current pressure.

[0087] Please see details Figure 2 Step S203 of the illustrated embodiment will not be described again here.

[0088] Step S404: Determine the reliability of the flight time difference based on multiple quality evaluation indicators.

[0089] Please see details Figure 2 Step S204 of the illustrated embodiment will not be described again here.

[0090] Step S405: When the reliability is greater than the first preset threshold, the flight time difference is compensated based on the current temperature and current pressure to obtain the compensated flight time difference.

[0091] Please see details Figure 2 Step S205 of the illustrated embodiment will not be described again here.

[0092] Step S406: Determine the flow rate of the gas to be measured based on the compensated time difference and the first distance.

[0093] Please see details Figure 2 Step S206 of the illustrated embodiment will not be described again here.

[0094] Step S407: When the reliability is greater than the first preset threshold, determine the uplink flight time based on the uplink waveform signal.

[0095] Step S408: Based on the current temperature and current pressure, compensate for the uplink flight time to obtain the compensated uplink flight time.

[0096] Step S409: When the reliability is greater than the first preset threshold, determine the downlink flight time based on the downlink waveform signal.

[0097] Step S410: Based on the current temperature and current pressure, compensate for the downlink flight time to obtain the compensated downlink flight time.

[0098] Specifically, the uplink flight time and downlink flight time can be determined by envelope detection or the absolute position of the relevant peak. The time from the leading edge of the first transmitted signal to a specific threshold point in the envelope of the uplink waveform signal is the uplink flight time, and the time from the leading edge of the second transmitted signal to a specific threshold point in the envelope of the downlink waveform signal is the downlink flight time. The specific threshold point refers to the starting point (peak point) of the first signal to arrive at the corresponding transceiver module.

[0099] In other embodiments, cross-correlation processing can be performed on the first transmitted signal and the uplink waveform signal, and the time corresponding to the maximum value of the obtained correlation peak can be determined as the uplink flight time; cross-correlation processing can be performed on the second transmitted signal and the downlink waveform signal, and the time corresponding to the maximum value of the obtained correlation peak can be determined as the downlink flight time.

[0100] After determining the uplink and downlink flight times, the uplink and downlink flight times can be compensated in a manner similar to step S205 described above. For example, the product of the uplink flight time and the first compensation coefficient can be used to determine the compensated uplink flight time, and the product of the downlink flight time and the second compensation coefficient can be used to determine the compensated downlink flight time. The first compensation coefficient can be determined based on the ratio of the historically determined theoretical uplink flight time to the actual uplink flight time, and the second compensation coefficient can be determined based on the ratio of the historically determined theoretical downlink flight time to the actual downlink flight time.

[0101] Step S411: Determine the speed of sound of the gas to be measured based on the compensated up-flight time, the compensated down-flight time, and the first distance.

[0102] Specifically, based on the compensated up-flight time, the compensated down-flight time, and the first distance, the speed of sound of the gas to be measured is determined by the following formula (3):

[0103] In the formula, This represents the speed of sound of the gas being measured. The speed of sound is obtained by harmonic averaging the upward and downward flight times, thus eliminating the influence of flow velocity. When the flow velocity is much smaller than the speed of sound, the speed of sound is approximately... .

[0104] Step S412: Determine the volume concentration of the gas to be tested based on the sound velocity of the gas to be tested and the correspondence between sound velocity and volume concentration.

[0105] Specifically, for a mixture of two known gases (such as a mixture of oxygen (O2) and nitrogen (N2) to be tested), the relationship between sound velocity and volume concentration can be expressed as shown in formula (4):

[0106] In the formula, This indicates the specific heat ratio of the gas mixture. Represents the universal gas constant. , The temperature of the gas mixture is measured in real time by a temperature sensor. This represents the average molar mass of the gas mixture.

[0107] Assuming the volume concentration of the first gas in the gas mixture is x, then It can be as shown in formula (5) and It can be as shown in formula (6).

[0108]

[0109] In the formula, This represents the isobaric molar heat capacity of the first gas. This indicates the volume concentration of the second gas in the gas mixture. This represents the isobaric molar heat capacity of the second gas. This represents the molar heat capacity at constant volume for the first gas. This represents the constant-volume molar heat capacity of the second gas. This represents the molar mass of the first gas. This indicates the molar mass of the second gas.

[0110] After determining the speed of sound of the gas to be measured, the volume concentration of the gas to be measured can be obtained based on the above formulas (4) to (6).

[0111] In this embodiment, determining the cross-correlation function of the uplink and downlink waveform signals based on Fourier transform can improve the efficiency of cross-correlation function determination. Before determining the cross-correlation function, filtering the uplink and downlink waveform signals can avoid phase distortion and improve the accuracy of the calculated cross-correlation function. After determining the initial sampling point corresponding to the initial maximum peak value from the cross-correlation function, cubic spline interpolation is performed on the correlation between the initial maximum peak value and multiple sampling points adjacent to the initial sampling point. Based on the target sampling point corresponding to the target maximum value in the obtained interpolation curve, the time difference of flight is determined, which can improve the accuracy of the obtained time difference of flight.

[0112] This invention employs cubic spline interpolation to process sampling points, enabling time resolution exceeding sampling rate limits. At a 10MHz sampling rate, interpolation can achieve a time resolution of 10ps, improving time measurement accuracy from 1ns-10ns to 50ps-100ps. If the accuracy is improved from 1ns (1000ps) to 50ps-100ps, it represents a 10-fold (1000ps / 100ps) to 20-fold (1000ps / 50ps) improvement. The measurement accuracy of gas volume concentration can be improved from 0.01%-0.1% to 0.001% (10ppm)-0.005% (50ppm).

[0113] This invention uses FFT to accelerate cross-correlation calculations, reducing the computational complexity from O(N) to O(N). 2 The processing power consumption is reduced to O(NlogN), which is 5 to 10 times faster than the traditional cross-correlation algorithm. Power consumption can be reduced by 40%, and memory requirements can be reduced by 50%. This allows real-time processing to be achieved even when the signal processor 130 is a low-power microcontroller, and the measurement system can be expanded into a battery-powered portable device.

[0114] This embodiment provides another ultrasonic-based gas flow velocity measurement method, which can be used in the aforementioned signal processor 130. Figure 7 This is a schematic flowchart of another ultrasonic-based gas flow velocity measurement method according to an embodiment of the present invention, as shown below. Figure 7 As shown, the process includes the following steps: Step S701: Obtain the uplink waveform signal and the downlink waveform signal.

[0115] Please see details Figure 2 Step S201 of the illustrated embodiment will not be described again here.

[0116] Step S702: Perform differential cross-correlation processing on the uplink and downlink waveform signals to obtain the time difference between the uplink and downlink waveform signals.

[0117] Please see details Figure 4 Step S402 of the illustrated embodiment will not be described again here.

[0118] Step S703: Obtain the current temperature and current pressure.

[0119] Please see details Figure 2 Step S203 of the illustrated embodiment will not be described again here.

[0120] Step S704: Determine the reliability of the flight time difference based on multiple quality evaluation indicators.

[0121] Specifically, step S704 above may include: Step S7041: Based on the quality evaluation index, determine the quality score using formula (7).

[0122]

[0123] In the formula, Indicates quality score, The weights represent the signal-to-noise ratio. This represents the score corresponding to the signal-to-noise ratio. The weights represent the peak-to-noise ratio. This represents the score corresponding to the peak-to-noise ratio. This indicates the weight corresponding to the width of the relevant peak. This represents the score corresponding to the width of the relevant peak. The weights corresponding to the deviations between the flight time difference and historical flight time differences. This represents the score corresponding to the deviation between the flight time difference and the historical flight time difference. In one example, , The value range is from 0 to 1.

[0124] For example, if If the score is 1 point, then the score is 1 point; if If the score is 0, then the score is 0. ,but The peak-to-noise ratio (PNR) is directly proportional to the corresponding score; the higher the PNR, the better. The larger the deviation between the flight time difference and the historical flight time difference, the more inversely proportional the corresponding score. If the deviation is less than the first threshold (e.g., 2%), then... The larger the value (closer to 1), the more inversely proportional the correlation peak width is to the corresponding score; the smaller the correlation peak width, the better. The larger.

[0125] Step S7042: Determine the reliability of the flight time difference based on the quality score.

[0126] Specifically, the quality score can be directly used as a measure of the reliability of the flight time difference.

[0127] Step S705: When the reliability is greater than the first preset threshold, the flight time difference is compensated based on the current temperature and current pressure to obtain the compensated flight time difference.

[0128] Specifically, step S705 above may include: Step S7051 involves inputting the current temperature and pressure into the compensation model and determining the deviation based on the output of the compensation model.

[0129] Step S7052: The difference between the flight time difference and the deviation amount is determined as the compensated flight time difference.

[0130] The compensation model characterizes the measurement errors caused by temperature and pressure changes. By utilizing the compensation model, the effects of temperature and pressure changes on the time-of-flight difference can be eliminated, enabling the ultrasonic-based gas flow velocity measurement device to maintain stable accuracy under different operating conditions. For example, the compensation model can be a machine learning model.

[0131] Optionally, the expression for the compensation model can be as shown in Equation (8), and the compensated flight time difference can be as shown in Equation (9).

[0132]

[0133] In the formula, Indicates the deviation amount. Indicates the temperature compensation coefficient. Indicates the current temperature. Indicates reference temperature. Indicates the pressure compensation coefficient. Indicates current pressure. Indicates reference pressure. Indicates a fixed offset. This indicates the compensated flight time difference. Indicates the time difference of flight.

[0134] The compensation model can be a linear regression model, and the temperature compensation coefficient, pressure compensation coefficient, and fixed offset in the compensation model can be determined based on historical data. The historical data includes historical flight time differences determined before the current flight time difference, the current temperature corresponding to the historical flight time difference, the current pressure corresponding to the historical flight time difference, and the measurement error corresponding to the historical flight time difference. The measurement error is the difference between the flight time difference calculated under the current temperature and current pressure and the flight time difference calculated under the reference temperature and reference pressure.

[0135] The ultrasonic-based gas velocity measurement device also features a circular buffer to store multiple historical data points. Using the least squares method and these historical data points, the temperature compensation coefficient, pressure compensation coefficient, and fixed offset can be calculated. After the compensation model converges, the flight time difference is compensated based on the current temperature, current pressure, and the compensation model. If the compensation model does not converge, the product of the compensation coefficient and the flight time difference can be used to determine the compensated flight time difference.

[0136] Each time the reference gas is calibrated, new data points are recorded and the compensation model is updated (using recursive least squares or sliding window batch processing). When the prediction error of the compensation model exceeds the threshold, the compensation model is reset or retrained.

[0137] Step S706: Determine the flow rate of the gas to be measured based on the compensated time difference and the first distance.

[0138] Please see details Figure 2 Step S206 of the illustrated embodiment will not be described again here.

[0139] Step S707: When the reliability is less than or equal to the first preset threshold and greater than the second preset threshold, mark the flight time difference and redetermine the flight time difference.

[0140] The second preset threshold is less than or equal to the first preset threshold. For example, the first preset threshold can be 0.6, and the second preset threshold can be 0.4.

[0141] Step S708: When the reliability is less than or equal to the second preset threshold, remove the time-of-flight difference and redetermine the time-of-flight difference after adjusting the transmission power of the ultrasonic pulse signal.

[0142] Step S709: If the reliability of a consecutive preset number is less than or equal to the second preset threshold, then a warning signal is triggered.

[0143] Specifically, if If the time difference is not found, it indicates that the determined flight time difference is unreliable. Discard the determined flight time difference and re-measure after adjusting the transmission power or gain of the ultrasonic pulse signal, and repeat steps S701 to S704. If this happens repeatedly... If so, an early warning signal will be output to prompt staff to check the ultrasonic-based gas flow rate measurement system; if If the result is positive, it indicates that the determined flight time difference is reliable. Based on the compensated flight time difference and the first distance, the flow rate of the gas to be measured is determined.

[0144] exist If the determined flight time difference is questionable, it is marked, and the flight time difference is re-determined for a second verification. The reliability of the re-determined flight time difference is then assessed. If so, then execute steps S705 and S706 above; if Perform steps S705 and S706 as described above, but do not store the determined time difference in the circular buffer.

[0145] In this embodiment, the reliability of each flight time measurement is quantitatively evaluated. Calculations continue only after the quality meets the standard (reliability exceeds a first preset threshold). This determines the reliability of the measurement and provides a basis for decisions regarding the ultrasonic-based gas flow rate measurement device (such as whether to use the current result, whether to trigger a retest or calibration). After meeting the quality standard, the flight time difference is compensated based on the current temperature, current pressure, and compensation model. This eliminates the influence of environmental factors such as temperature and pressure on the flight time difference, improving the measurement stability and accuracy of the ultrasonic-based gas flow rate measurement device under different operating conditions.

[0146] This invention can extend the applicable operating temperature range of the measurement system from 0℃-50℃ to -20℃-70℃, the self-diagnostic function can reduce the failure rate by 60%, extend the service life from 3-5 years to 8-10 years, and predictive maintenance can reduce the need for on-site maintenance. The measurement system can meet the measurement needs of high-precision scenarios such as semiconductor manufacturing and medical equipment, and can also adapt to the high temperature, high humidity and vibration environment of industrial sites.

[0147] In some optional embodiments, before determining the reliability of the time-of-flight difference, the ultrasonic-based gas velocity measurement method further includes: determining whether the time-of-flight difference is within a physically reasonable range; if the time-of-flight difference is within a physically reasonable range, determining the reliability of the time-of-flight difference based on multiple quality evaluation indicators; if the time-of-flight difference exceeds the physically reasonable range, directly removing the time-of-flight difference and re-determining the time-of-flight difference after adjusting the transmission power of the ultrasonic pulse signal.

[0148] The physical reasonable range is a theoretical range estimated based on the current temperature and pressure, such as the time difference range corresponding to the air speed of sound of 330m / s to 350m / s. When the flight time difference is greater than 3 times the maximum value in the physical reasonable range, the flight time difference is considered to be outside the physical reasonable range.

[0149] In this embodiment, based on the physical reasonable range, it can be determined whether the flight time difference conforms to physical laws, and data that meets the reliability requirements but does not conform to physical laws can be eliminated, thereby further improving the accuracy of the measurement.

[0150] This embodiment also provides an ultrasonic-based gas flow rate measuring device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0151] This embodiment provides a gas flow rate measurement device based on ultrasound, such as... Figure 8 As shown, it includes: The first acquisition module 801 is used to acquire an uplink waveform signal and a downlink waveform signal, wherein the uplink waveform signal is an ultrasonic pulse signal received by the second transceiver from the first transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first transceiver from the second transceiver. The first transceiver and the second transceiver are arranged opposite each other along the propagation direction of the gas to be measured. The differential processing module 802 is used to perform differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal; The second acquisition module 803 is used to acquire the current temperature and the current pressure, wherein the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal; The reliability determination module 804 is used to determine the reliability of the flight time difference based on multiple quality evaluation indicators, wherein the multiple quality evaluation indicators include at least two of the following: signal-to-noise ratio, peak-to-noise ratio, deviation value of flight time difference and historical flight time difference, and relevant peak width. The environmental compensation module 805 is used to compensate for the flight time difference based on the current temperature and current pressure when the reliability level is greater than the first preset threshold, and obtain the compensated flight time difference. The flow velocity determination module 806 is used to determine the flow velocity of the gas to be measured based on the compensated time difference of flight and a first distance, wherein the first distance is the distance between the first signal transceiver and the second signal transceiver in the direction of propagation of the gas to be measured.

[0152] This embodiment also provides a gas flow velocity measurement system based on ultrasound, such as... Figure 1 As shown, it includes: The first transceiver 110 is used to transmit ultrasonic pulse signals to the second transceiver and receive ultrasonic pulse signals from the second transceiver. The first transceiver and the second transceiver are arranged opposite each other along the propagation direction of the gas to be measured. The second transceiver 120 is used to send ultrasonic pulse signals to the first transceiver and receive ultrasonic pulse signals from the first transceiver. Environmental sensor 140 is used to detect the temperature and pressure of the gas to be measured; The signal processor 130 is connected to a first signal transceiver, a second signal transceiver, and an environmental sensor, and is used to acquire uplink waveform signals and downlink waveform signals, wherein the uplink waveform signal is an ultrasonic pulse signal received by the second signal transceiver from the first signal transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first signal transceiver from the second signal transceiver. The signal processor 130 is also used to perform differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time difference between the uplink waveform signal and the downlink waveform signal; The signal processor 130 is also used to acquire the current temperature and current pressure, wherein the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal; The signal processor is also used to determine the reliability of the time difference based on multiple quality evaluation indicators, including at least two of the following: signal-to-noise ratio, peak-to-noise ratio, deviation of the time difference and the historical time difference, and the relevant peak width. The signal processor 130 is also used to compensate for the flight time difference based on the current temperature and current pressure when the reliability is greater than a first preset threshold, and obtain the compensated flight time difference. The signal processor 130 is also used to determine the flow velocity of the gas to be measured based on the compensated time difference of flight and a first distance, wherein the first distance is the distance between the first signal transceiver and the second signal transceiver in the direction of propagation of the gas to be measured.

[0153] The signal processor may include, for example, Figure 8 The ultrasonic gas measurement shown can also be performed by the electronic device or the controller within the electronic device described below.

[0154] Furthermore, the first transceiver also includes a first ultrasonic sensor, a first analog-to-digital converter, and a first programmable gain amplifier, and the second transceiver also includes a second ultrasonic sensor, a second analog-to-digital converter, and a second programmable gain amplifier, wherein the first programmable gain amplifier and the second programmable gain amplifier are used to amplify the ultrasonic pulse signal.

[0155] Optionally, such as Figure 9 As shown, the ultrasonic-based gas flow rate measuring device also includes a communication and display 150 connected to the signal processor 130. The communication and display 150 is used to display parameters such as the compensated time-of-flight difference, the gas flow rate to be measured, and the volume concentration.

[0156] Specifically, the measurement process of the ultrasonic-based gas flow velocity measurement system includes the following steps: Step 1, system initialization, specifically involves configuring ultrasonic transmission parameters (frequency, pulse count, amplitude), configuring analog-to-digital converter parameters (sampling rate, gain), initializing environmental sensors, and loading historical calibration parameters.

[0157] Step 2: Perform uplink measurement. The first ultrasonic sensor emits an ultrasonic pulse signal, the second ultrasonic sensor receives the ultrasonic pulse signal, and the second analog-to-digital converter collects the ultrasonic pulse signal and stores it as an uplink waveform signal.

[0158] Step 3: Perform downlink measurement. The second ultrasonic sensor emits an ultrasonic pulse signal, the first ultrasonic sensor receives the ultrasonic pulse signal, and the first analog-to-digital converter collects the ultrasonic pulse signal and stores it as a downlink waveform signal.

[0159] Step 4: Differential cross-correlation processing. Digital bandpass filtering is applied to the uplink and downlink waveform signals. The cross-correlation function of the two waveform signals is calculated. The peak position of the cross-correlation is determined by interpolation. The time difference between the uplink and downlink waveform signals is calculated, and the time difference is updated by applying a compensation model related to temperature and pressure.

[0160] Step 5: Calculate volume concentration and flow rate. Calculate gas flow rate based on time-of-flight difference, calculate gas sound speed based on absolute time of flight, calculate gas volume concentration based on sound speed, and output the measurement results.

[0161] The ultrasonic-based gas flow velocity measuring device provided in this embodiment of the invention can execute the ultrasonic-based gas flow velocity measuring method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0162] Figure 10This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0163] like Figure 10 As shown, the electronic device includes a memory 1010 and a processor 1020. The memory 1010 stores a computer program, and the processor 1020 is configured to run the computer program to perform the steps in any of the above-described etching process monitoring method embodiments, or to perform the steps in any of the above-described ultrasonic-based gas flow rate measurement method embodiments. Figure 10 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0164] Furthermore, the electronic device also includes a communication interface 1030 for communicating with other devices or communication networks.

[0165] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as recordable on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and subsequently stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the ultrasonic-based gas flow rate measurement method shown in the above embodiments is implemented.

[0166] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0167] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for measuring gas flow velocity based on ultrasound, characterized in that, The method includes: Acquire uplink and downlink waveform signals, wherein the uplink waveform signal is an ultrasonic pulse signal received by the second transceiver from the first transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first transceiver from the second transceiver, wherein the first transceiver and the second transceiver are arranged opposite each other along the propagation direction of the gas to be measured; Differential cross-correlation processing is performed on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal; Obtain the current temperature and current pressure, wherein the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal; The quality score is determined based on multiple quality evaluation indicators using the following formula: ； The multiple quality evaluation indicators include signal-to-noise ratio, peak-to-noise ratio, the deviation between the flight time difference and the historical flight time difference, and the relevant peak width. This indicates the quality score. This represents the weight corresponding to the signal-to-noise ratio. This represents the numerical score corresponding to the signal-to-noise ratio. This represents the weight corresponding to the peak-to-noise ratio. This represents the numerical value corresponding to the peak-to-noise ratio. This indicates the weight corresponding to the width of the relevant peak. This represents the score corresponding to the width of the relevant peak. The weight representing the deviation value between the flight time difference and the historical flight time difference. This represents the score corresponding to the deviation between the flight time difference and the historical flight time difference; The expression for the signal-to-noise ratio is: ; Indicates the signal-to-noise ratio. This represents the root mean square value of the effective portion of the received signal. The root mean square value of the noise is represented; the expression for the peak-to-noise ratio is: ; This indicates the peak-to-noise ratio. This represents the peak height of the main peak of the cross-correlation function. The noise floor mean of the main peak of the cross-correlation function is represented; the deviation between the flight time difference and the historical flight time difference refers to the deviation between the flight time difference and the historical median value; the correlation peak width refers to the distance between the sampling point positions corresponding to the half-power points on both sides of the main peak of the cross-correlation function. Based on the quality score, the reliability of the flight time difference is determined; When the reliability level is greater than a first preset threshold, the current temperature and current pressure are input into the compensation model, and the deviation is determined based on the output of the compensation model. The compensation model characterizes the measurement error caused by temperature and pressure changes; the expression for the compensation model is: ； In the formula, Indicates the deviation amount. Indicates the temperature compensation coefficient. This indicates the current temperature. Indicates reference temperature. Indicates the pressure compensation coefficient. This indicates the current pressure. Indicates reference pressure. Indicates a fixed offset; The difference between the flight time difference and the deviation amount is determined as the compensated flight time difference; The flow rate of the gas under test is determined based on the compensated time difference of flight and the first distance, wherein the first distance is the distance between the first transceiver and the second transceiver in the direction of propagation of the gas under test.

2. The method according to claim 1, characterized in that, The step of performing differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal includes: Based on Fourier transform, the cross-correlation function of the uplink waveform signal and the downlink waveform signal is determined; Determine the initial sampling point corresponding to the initial maximum peak value from the cross-correlation function; The initial maximum peak value and the correlation between the initial sampling point and the multiple sampling points adjacent to the initial sampling point are subjected to cubic spline interpolation to obtain the interpolation curve; The flight time difference is determined based on the target sampling point corresponding to the target maximum value determined from the interpolation curve.

3. The method according to claim 2, characterized in that, Before performing differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal, the method further includes: The uplink waveform signal and the downlink waveform signal are filtered. The determination of the cross-correlation function between the uplink and downlink waveform signals based on Fourier transform includes: Based on Fourier transform, the cross-correlation function of the filtered uplink waveform signal and the filtered downlink waveform signal is determined.

4. The method according to any one of claims 1 to 3, characterized in that, The method further includes: When the reliability level is less than or equal to a first preset threshold and greater than a second preset threshold, the flight time difference is marked and the flight time difference is redefined, wherein the second preset threshold is less than or equal to the first preset threshold; When the reliability is less than or equal to the second preset threshold, the time-of-flight difference is removed, and the time-of-flight difference is re-determined after adjusting the transmission power of the ultrasonic pulse signal.

5. The method according to claim 4, characterized in that, The method further includes: If the reliability of a consecutive preset number of times is less than or equal to the second preset threshold, an early warning signal is triggered.

6. The method according to any one of claims 1 to 3, characterized in that, The method further includes: When the reliability level is greater than a first preset threshold, the uplink flight time is determined based on the uplink waveform signal; The uplink flight time is compensated based on the current temperature and the current pressure to obtain the compensated uplink flight time. When the reliability level is greater than a first preset threshold, the downlink flight time is determined based on the downlink waveform signal; The downlink flight time is compensated based on the current temperature and the current pressure to obtain the compensated downlink flight time; The speed of sound of the gas under test is determined based on the compensated up-flight time, the compensated down-flight time, and the first distance. The volume concentration of the gas to be tested is determined based on the sound velocity of the gas and the correspondence between sound velocity and volume concentration.

7. A gas flow velocity measuring device based on ultrasound, characterized in that, The device includes: The first acquisition module is used to acquire an uplink waveform signal and a downlink waveform signal, wherein the uplink waveform signal is an ultrasonic pulse signal received by the second transceiver from the first transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first transceiver from the second transceiver. The first transceiver and the second transceiver are arranged opposite each other along the propagation direction of the gas to be measured. The differential processing module is used to perform differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal; The second acquisition module is used to acquire the current temperature and the current pressure, wherein the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal; The reliability determination module is used to determine the quality score based on multiple quality evaluation indicators using the following formula: ； The multiple quality evaluation indicators include signal-to-noise ratio, peak-to-noise ratio, the deviation between the flight time difference and the historical flight time difference, and the relevant peak width. This indicates the quality score. This represents the weight corresponding to the signal-to-noise ratio. This represents the numerical score corresponding to the signal-to-noise ratio. This represents the weight corresponding to the peak-to-noise ratio. This represents the numerical value corresponding to the peak-to-noise ratio. This indicates the weight corresponding to the width of the relevant peak. This represents the score corresponding to the width of the relevant peak. The weight representing the deviation value between the flight time difference and the historical flight time difference. This represents the score corresponding to the deviation between the flight time difference and the historical flight time difference; The expression for the signal-to-noise ratio is: ; Indicates the signal-to-noise ratio. This represents the root mean square value of the effective portion of the received signal. The root mean square value of the noise is represented; the expression for the peak-to-noise ratio is: ; Indicates peak-to-noise ratio. This represents the peak height of the main peak of the cross-correlation function. The noise floor mean of the main peak of the cross-correlation function is represented; the deviation between the flight time difference and the historical flight time difference refers to the deviation between the flight time difference and the historical median value; the correlation peak width refers to the distance between the sampling points corresponding to the half-power points on both sides of the main peak of the cross-correlation function. The reliability determination module is further configured to determine the reliability of the flight time difference based on the quality score. An environmental compensation module is used to input the current temperature and current pressure into a compensation model when the reliability level is greater than a first preset threshold, and determine the deviation based on the output of the compensation model. The compensation model characterizes the measurement error caused by temperature and pressure changes; the expression of the compensation model is: ； In the formula, Indicates the deviation amount. Indicates the temperature compensation coefficient. This indicates the current temperature. Indicates reference temperature. Indicates the pressure compensation coefficient. This indicates the current pressure. Indicates reference pressure. Indicates a fixed offset; The environmental compensation module is also used to determine the difference between the flight time difference and the deviation as the compensated flight time difference; The flow rate determination module is used to determine the flow rate of the gas to be tested based on the compensated time-of-flight difference and a first distance, wherein the first distance is the distance between the first transceiver and the second transceiver in the direction of propagation of the gas to be tested.

8. A gas flow velocity measurement system based on ultrasound, characterized in that, The system includes: A first transceiver is used to transmit ultrasonic pulse signals to a second transceiver and to receive ultrasonic pulse signals from the second transceiver. The first transceiver and the second transceiver are arranged opposite each other along the propagation direction of the gas to be measured. The second transceiver is used to send ultrasonic pulse signals to the first transceiver and to receive ultrasonic pulse signals from the first transceiver. An environmental sensor is used to detect the temperature and pressure of the gas to be tested; A signal processor, connected to the first signal transceiver, the second signal transceiver, and the environmental sensor, is used to acquire uplink waveform signals and downlink waveform signals, wherein the uplink waveform signal is an ultrasonic pulse signal received by the second signal transceiver from the first signal transceiver, and the downlink waveform signal is an ultrasonic pulse signal received by the first signal transceiver from the second signal transceiver; The signal processor is further configured to perform differential cross-correlation processing on the uplink waveform signal and the downlink waveform signal to obtain the time-of-flight difference between the uplink waveform signal and the downlink waveform signal; The signal processor is further configured to acquire the current temperature and current pressure, wherein the current temperature is the temperature of the gas to be measured at the time corresponding to the uplink waveform signal, and the current pressure is the pressure of the gas to be measured at the time corresponding to the uplink waveform signal; The signal processor is also used to determine a quality score based on multiple quality evaluation indicators using the following formula: ； The multiple quality evaluation indicators include signal-to-noise ratio, peak-to-noise ratio, the deviation between the flight time difference and the historical flight time difference, and the relevant peak width. This indicates the quality score. This represents the weight corresponding to the signal-to-noise ratio. This represents the numerical score corresponding to the signal-to-noise ratio. This represents the weight corresponding to the peak-to-noise ratio. This represents the numerical value corresponding to the peak-to-noise ratio. This indicates the weight corresponding to the width of the relevant peak. This represents the score corresponding to the width of the relevant peak. The weight representing the deviation value between the flight time difference and the historical flight time difference. This represents the score corresponding to the deviation between the flight time difference and the historical flight time difference; The expression for the signal-to-noise ratio is: ; Indicates the signal-to-noise ratio. This represents the root mean square value of the effective portion of the received signal. The root mean square value of the noise is represented; the expression for the peak-to-noise ratio is: ; Indicates peak-to-noise ratio. This represents the peak height of the main peak of the cross-correlation function. The noise floor mean of the main peak of the cross-correlation function is represented; the deviation between the flight time difference and the historical flight time difference refers to the deviation between the flight time difference and the historical median value; the correlation peak width refers to the distance between the sampling points corresponding to the half-power points on both sides of the main peak of the cross-correlation function. The signal processor is also used to determine the reliability of the time difference based on the quality score; The signal processor is further configured to, when the reliability is greater than a first preset threshold, input the current temperature and the current pressure into a compensation model, and determine the deviation based on the output of the compensation model, wherein the compensation model is used to characterize the measurement error caused by temperature and pressure changes; the expression of the compensation model is: ； In the formula, Indicates the deviation amount. Indicates the temperature compensation coefficient. This indicates the current temperature. Indicates reference temperature. Indicates the pressure compensation coefficient. This indicates the current pressure. Indicates reference pressure. Indicates a fixed offset; The signal processor is further configured to determine the difference between the flight time difference and the deviation as the compensated flight time difference; The signal processor is further configured to determine the flow velocity of the gas under test based on the compensated time-of-flight difference and a first distance, wherein the first distance is the distance between the first signal transceiver and the second signal transceiver in the direction of propagation of the gas under test.

9. The system according to claim 8, characterized in that, The system also includes a communication and display, which is connected to the signal processor and is used to display the compensated time-of-flight difference and the flow rate of the gas under test.

10. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the ultrasonic-based gas flow rate measurement method according to any one of claims 1 to 6.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the ultrasonic-based gas flow rate measurement method according to any one of claims 1 to 6.

12. A computer program product, characterized in that, Includes computer instructions for causing a computer to execute the ultrasonic-based gas flow rate measurement method according to any one of claims 1 to 6.

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