Bridge flow measurement method, device and system based on real-time water level triggering

Abstract

This application relates to the field of flow measurement technology, specifically to a bridge-type flow measurement method, device, and system based on real-time water level triggering. The method includes: acquiring the water level at a flow monitoring point in real time and determining whether a measurement command is triggered; when triggered, acquiring echo signals from multiple measurements; based on the significance of local peaks, signal strength, irregularity, bandwidth in the frequency domain, and high-frequency energy attenuation of the echo signals from each measurement, and combined with the difference between the frequency of the echo signals and the frequency of the transmitted signals, constructing usable coefficients for each measurement; thereby filtering usable signals from all echo signals after the current measurement command is triggered, and calculating the river flow at the flow monitoring point at the time the measurement command is triggered. This application improves the accuracy of river flow measurement by filtering echo signals containing more river flow information from all measurement echo signals.

Description

Technical Field

[0001] This application relates to the field of flow measurement technology, specifically to a bridge flow measurement method, device, and system based on real-time water level triggering. Background Technology

[0002] The large-scale construction of various water storage, diversion, and lifting projects, as well as river regulation, sand mining, and landscape dams, has not only altered the natural properties of rivers but also the water quality, sediment characteristics, and control conditions of the river sections where monitoring stations are located. This has created significant difficulties for flow measurement and undermined the representativeness of hydrological stations and the consistency of hydrological data. In particular, frequent adjustments by water conservancy projects can lead to unpredictable flow measurements, necessitating real-time monitoring. The backwater effect of downstream dams and the irregular regulation of gates can cause turbulent flow patterns in rivers, making it extremely difficult to measure flow using rotor current meters or ADCP (Acoustic Doppler Current Profiler).

[0003] Currently, fully automated bridge-type flow monitoring systems, also known as vertical ADCP flow measurement, are commonly used for flow measurement. This method can obtain high-precision flow measurement results even in rivers with turbulent vertical and lateral velocity distributions. However, in practical applications, the measurement accuracy of ADCP is somewhat dependent on water conditions. With frequent changes in hydraulic facilities, the amount of suspended particles in the river may be too high or too low, and the side lobes of the acoustic wave will generate additional echo signals, resulting in a large amount of noise in the measured echo signal. This, in turn, leads to an overestimation or underestimation of the measured flow velocity, ultimately causing serious deviations in the flow measurement results. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a bridge-type flow measurement method, device, and system based on real-time water level triggering. The specific technical solution adopted is as follows: In a first aspect, embodiments of this application provide a bridge flow measurement method based on real-time water level triggering, the method comprising the following steps: The system acquires the water level at the flow monitoring point in real time and determines whether a measurement command has been triggered. When triggered, it performs multiple measurements and acquires the echo signals from these measurements. The total duration of echo reception for each measurement is divided into several time intervals. Based on the significance of local peaks, signal strength, bandwidth in the frequency domain, and high-frequency energy attenuation in the echo signals of each measurement, a hydrological interference coefficient for each measurement is constructed to characterize the degree of hydrological interference on the echo signals of each measurement. Based on the waveform differences, peak count differences, and frequency differences between the echo signals and the transmitted signals across all time intervals in each measurement, a sidelobe interference coefficient is constructed for each measurement to characterize the degree of sidelobe interference on the echo signals. Combined with the hydrological interference coefficient, a usable coefficient is constructed for each measurement. This allows us to filter usable signals from the echo signals of all measurements after the current measurement command is triggered, thereby calculating the river flow at the flow monitoring point at the time the current measurement command is triggered.

[0005] Preferably, the specific process for determining whether a measurement command has been triggered is as follows: Calculate the absolute difference between the water level at the current sampling time and the water level at the previous sampling time, and record the ratio of the absolute difference to the water level at the previous sampling time as the water level change rate at the current sampling time; A measurement command is generated when the rate of change of water level at the current sampling time exceeds a preset rate of change threshold, or when the time since the last measurement command is more than a preset trigger time; otherwise, no measurement command is triggered.

[0006] Preferably, the method for constructing the hydrological interference coefficients for each measurement is as follows: The absolute difference between the maximum peak value and the previous adjacent trough value in the echo signal of each measurement is calculated. The ratio of the bandwidth of the echo signal in each measurement to the preset maximum bandwidth is calculated. The amplitude-frequency sequence of the echo signal in each time interval of each measurement is obtained, and the difference between the high-frequency energy in the amplitude-frequency sequence of the echo signal in the first time interval and the last time interval of each measurement is calculated. Calculate the average amplitude of the echo signal from each measurement; The hydrological interference coefficients of each measurement are positively correlated with the absolute difference, the ratio, and the difference, and negatively correlated with the mean amplitude.

[0007] Preferably, the method for constructing the sidelobe interference coefficients of each measurement is as follows: Based on the waveform differences between the echo signals in each time interval of each measurement, the morphological difference coefficient of each measurement is obtained. Calculate the variance among the total number of peak values ​​in the echo signals across all time intervals in each measurement. The mean value of the center frequencies of the echo signals in all time intervals of each measurement is calculated, and the absolute difference between the mean value and the preset frequency when the sound wave is emitted is calculated. The sidelobe interference coefficients of each measurement are positively correlated with the morphological difference coefficients and the variance, and negatively correlated with the absolute difference.

[0008] Preferably, the method for obtaining the morphological difference coefficient of each measurement is as follows: Extract the envelope of the echo signal for each time interval in each measurement; Calculate the DTW distance between the echo signal envelopes of all adjacent time intervals in each measurement, and record the mean of all DTW distances as the morphological difference coefficient for each measurement.

[0009] Preferably, the usability coefficients of each measurement are negatively correlated with both the hydrological interference coefficient and the sidelobe interference coefficient.

[0010] Preferably, the available signal refers to the echo signal obtained from the measurement process with the largest available coefficient among all measurements after the current measurement command is triggered.

[0011] Preferably, the method for calculating the river flow at the current time the measurement command is triggered is as follows: Calculate the Doppler frequency shift of the available signal at the current flow monitoring point after the current measurement command is triggered; Calculate the river flow velocity at the current time the measurement command is triggered: In the formula, v is the river flow velocity at the current time the measurement command is triggered; y is the Doppler frequency shift of the available signal at the current time the measurement command is triggered. is the preset frequency for transmitting sound waves; c is the pre-acquired speed of sound in water; The angle between the emitted acoustic beam and the measuring vertical line; The product of the river velocity at the current time the measurement command is triggered, the pre-determined river profile area, and the preset cross-sectional velocity conversion factor is recorded as the river flow at the current time the measurement command is triggered.

[0012] Secondly, embodiments of this application provide a bridge flow measurement device based on real-time water level triggering, the bridge flow measurement device comprising: a data acquisition module, an available signal filtering module, and a flow measurement module.

[0013] The data acquisition module is used to acquire the water level at the flow monitoring point in real time and determine whether a measurement command is triggered. When triggered, it performs multiple measurements and acquires the echo signals from the multiple measurements. The available signal filtering module is used to construct the availability coefficients for each measurement based on the degree of hydrological environmental interference and sidelobe interference of the echo signals of each measurement, thereby filtering out available signals from the echo signals of all measurements after the current measurement command is triggered. The flow measurement module is used to calculate the river flow at the current time the measurement command is triggered, based on available signals.

[0014] Thirdly, embodiments of this application also provide a bridge flow measurement system based on real-time water level triggering. The system includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described bridge flow measurement methods based on real-time water level triggering.

[0015] As can be seen from the above embodiments, the bridge flow measurement method, device, and system based on real-time water level triggering provided in this application have at least the following beneficial effects: This application addresses the problem that traditional ADCP flow measurement is susceptible to interference from river hydrological environment and sidelobe interference, resulting in insufficient effective information and excessive noise in the echo signal, leading to significant deviations in the calculated river flow. By analyzing the local peak significance, signal strength, bandwidth, and high-frequency energy attenuation of the echo signals acquired in each measurement, a hydrological interference coefficient is constructed to assess the degree of hydrological environmental interference on the echo signals of each measurement. Furthermore, by analyzing the irregularity and frequency shift characteristics of the echo signals from each measurement, a sidelobe interference coefficient is constructed to assess the degree of sidelobe interference on the echo signals of each measurement. Finally, a usability coefficient is constructed to filter usable signals. The river velocity and flow are then calculated using usable signals containing relatively complete river flow information, improving the accuracy of velocity calculation and thus enhancing the accuracy of flow measurement. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the steps of a bridge flow measurement method based on real-time water level triggering, as provided in one embodiment of this application; Figure 2 This is a schematic diagram of a bridge-type flow measurement device based on real-time water level triggering, provided as an embodiment of this application. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application to achieve the intended inventive purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a bridge-type flow measurement method, device, and system based on real-time water level triggering proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] The following description, in conjunction with the accompanying drawings, details the specific scheme of the bridge flow measurement method, equipment, and system based on real-time water level triggering provided in this application.

[0021] Please see Figure 1 The diagram illustrates a flowchart of a bridge flow measurement method based on real-time water level triggering, according to an embodiment of this application. The method includes the following steps: Step 1: Obtain the water level at the flow monitoring point in real time and determine whether a measurement command has been triggered; when triggered, perform multiple measurements and obtain the echo signals from the multiple measurements.

[0022] This application enables automated flow measurement at any flow monitoring point in a river using a fully automatic bridge-type flow measurement system. Before measurement, the water level at the flow monitoring point is collected in real time using a water level sensor, with a sampling frequency set to once per hour. The absolute difference between the water level at the current sampling time and the water level at the previous sampling time is calculated, and the ratio of the absolute difference to the water level at the previous sampling time is recorded as the water level change rate at the current sampling time. When the water level change rate at the current sampling time exceeds a preset change rate threshold (30% in this embodiment), or when the time since the last triggering of the measurement command exceeds a preset triggering time (24 hours in this embodiment), a measurement command is generated; otherwise, no measurement command is triggered. After receiving the measurement command, the measurement system starts the circulating winch, which drives the flow measurement device to move above the flow measurement vertical line and performs N measurements (N is the preset number of measurements, which ranges from 5 to 10, and in this embodiment, N is 8). The specific process of each measurement is as follows: the lifting winch lowers the lead weight embedded with ADCP below the water surface. When the riverbed detection device detects that the lead weight has descended to the preset flow measurement depth, the lead weight stops descending and emits a signal of a preset frequency into the water for a duration of Umin (in this embodiment, U is 0.5min). After the transmission is completed, the lifting winch lifts the lead weight above the water surface and transmits the echo signal data received by ADCP to the remote server using the communication module.

[0023] Step 2: Divide the total duration of echo reception for each measurement into several time intervals. Based on the significance of local peaks, signal strength, bandwidth in the frequency domain, and high-frequency energy attenuation in the echo signals of each measurement, construct the hydrological interference coefficient for each measurement to characterize the degree of hydrological environmental interference to the echo signals of each measurement.

[0024] For ADCP, the principle of current measurement is to emit sound wave pulses of a known frequency into the water. Scattering objects (such as suspended particles like silt) moving with the water flow reflect the sound waves, transmitting the echo signals back to ADCP. ADCP analyzes the Doppler frequency shift between the received echo frequency and the transmitted frequency to calculate the water flow velocity. Therefore, the river hydrological environment is the most direct external factor affecting the accuracy of ADCP.

[0025] In actual measurement processes, factors such as weather, the operation of upstream water conservancy facilities, and discharges around the river may affect the concentration of suspended particles in the river, causing changes. For example, the opening of floodgates and the release of water from upstream water conservancy facilities, as well as rainfall, can cause water levels to rise, resulting in a significant decrease in the concentration of suspended particles in the water. The lack of effective scatterers in the water leads to weak echo signals. Alternatively, sewage systems around the river may discharge large amounts of suspended particles, causing the concentration of suspended particles in the water to rise. A large number of suspended particles will strongly absorb and scatter sound waves, causing severe attenuation of sound waves along the propagation path, which will also weaken the echo signal. Ultimately, the effective information may be covered by noise, and ADCP cannot distinguish the true situation of the echo signal at this time, easily mistaking noise information for river flow information, leading to errors in subsequent flow calculations. Furthermore, the turbulence of river currents or the movement of wind on the water's surface can create waves, drawing air into the water and forming a bubble layer. When sound waves propagate into this bubble layer, the bubbles undergo resonant scattering. Since the scattering cross-section is much larger than that of suspended particles in the water, the scattering is amplified, leading to abnormal changes in the signal intensity of the resulting echo signal. Therefore, before using echo signals to measure flow rate, it is necessary to analyze the accuracy of the echo signals acquired from each measurement and filter out the accurate echo signals from all available data.

[0026] Specifically, when using ADCP to measure water flow velocity, when the concentration of suspended particles in the river is low, the sound waves emitted by ADCP cannot form an effective echo signal due to the lack of scatterers. Therefore, the echo signal received by ADCP contains a significant amount of noise, resulting in a reduced overall signal strength in the time domain, noticeable waveform differences, and a large overall bandwidth in the frequency domain. Conversely, when the concentration of suspended particles in the river is high, the sound waves emitted by ADCP will reflect more in the near-field region (i.e., the water closest to the float). However, due to the high concentration of suspended particles, the sound waves attenuate faster during propagation, leading to a significant decrease in echo signal strength. In the time domain, the echo signal strength gradually and rapidly decreases over time, while in the frequency domain, more high-frequency components appear initially and gradually decrease over time. Furthermore, when a bubble layer appears in the river, the resonant scattering of sound waves within the bubbles causes additional peaks in the echo signal in the time domain.

[0027] Based on the above analysis, in order to characterize the interference characteristics of the river hydrological environment on the echo signal, the hydrological interference coefficient in a single measurement process can be represented by analyzing the time-domain signal intensity variation characteristics, signal intensity distribution characteristics, and frequency domain distribution variation characteristics of the echo signal at different times. That is, if the echo signal has a lower intensity in the time domain and has local peaks, and a larger signal bandwidth and faster attenuation of high-frequency components in the frequency domain, it indicates that the current echo signal is more likely to be interfered with by the river hydrological environment, and the less effective information is in the echo signal, the lower its usability.

[0028] Based on the above characteristics, the total echo reception time for each measurement is divided into time intervals with a preset duration (30 seconds in this embodiment). The peak and trough values ​​of the echo signal during each measurement are obtained. Simultaneously, to characterize the frequency domain distribution of the echo signal across different time intervals, the echo signal within each time interval is used as input, and the amplitude-frequency sequence of the echo signal within each time interval is output using a Fourier transform algorithm. In this embodiment, the frequency range greater than or equal to 20kHz is defined as the high-frequency region, and the frequency range less than 20kHz is defined as the low-frequency region.

[0029] In a preferred embodiment, based on the significance of local peaks, signal strength, bandwidth, and high-frequency energy attenuation in the echo signals of each measurement, a hydrological interference coefficient is constructed for each measurement. This coefficient characterizes the degree of hydrological environmental interference experienced by the echo signals of each measurement. The method for constructing the hydrological interference coefficient for each measurement is as follows: The absolute difference between the maximum peak value and the preceding adjacent trough value in the echo signals of each measurement is calculated; the ratio of the bandwidth of the echo signals of each measurement to a preset maximum bandwidth is calculated; the amplitude-frequency sequence of the echo signals in each time interval of each measurement is obtained; the difference in high-frequency energy in the amplitude-frequency sequence of the echo signals in the first and last time intervals of each measurement is calculated; the mean amplitude of the echo signals of each measurement is calculated. The hydrological interference coefficient for each measurement is positively correlated with the absolute difference, the ratio, and the difference, and negatively correlated with the mean amplitude. The positive correlation refers to the dependent variable increasing (decreasing) as the independent variable increases (decreases), while the negative correlation refers to the dependent variable decreasing (increasing) as the independent variable increases (decreases).

[0030] In this embodiment, the hydrological interference coefficient of the i-th measurement is denoted as . Its specific expression is: In the formula, Let be the hydrological interference coefficient for the i-th measurement; It is the absolute difference between the maximum value of the peak value in the echo signal of the i-th measurement and its previous adjacent trough value; Let be the average amplitude of the echo signal from the i-th measurement; The ratio of the echo signal bandwidth of the i-th measurement to the preset maximum bandwidth, wherein the preset maximum bandwidth is derived based on the physical upper limit of the device or statistical analysis of historical normal flow measurement data; , These are the high-frequency energy in the amplitude-frequency sequence of the echo signal in the first time interval of the i-th measurement, and the high-frequency energy in the amplitude-frequency sequence of the echo signal in the last time interval, respectively. This is a preset constant used to prevent the denominator from being 0, and its value ranges from 0.01 to 0.1. In this embodiment, it is set to 0.1. For the normalization function, the minimum-maximum normalization method is used in this embodiment. The minimum and maximum values ​​are determined based on the corresponding parameter sets in all measurements after the current measurement command is triggered. When the maximum and minimum values ​​in the parameter set are equal, the normalization result is set to a value of 0.5.

[0031] in, The larger the value, the more obvious the local peak characteristics in the echo signal of the i-th measurement are, and the more likely it is to be affected by environmental interference; The smaller the value, the weaker the overall echo signal strength of the i-th measurement, and the more likely it is to be affected by environmental interference; The larger the value, the wider the bandwidth of the echo signal in the frequency domain of the i-th measurement, and the more likely there is noise interference in the echo signal; The larger the value of , the more the high-frequency components in the echo signal of the i-th measurement decrease, and the more likely the echo signal of that measurement is affected by environmental interference. In summary, The larger the value, the greater the interference of the hydrological environment on the echo signal of the i-th measurement.

[0032] Step 3: Based on the waveform differences, peak quantity differences, and frequency differences between the echo signals and the transmitted signals in all time intervals of each measurement, construct the sidelobe interference coefficient for each measurement. This coefficient characterizes the degree of sidelobe interference on the echo signals of each measurement. Combined with the hydrological interference coefficient, construct the usable coefficient for each measurement. This allows us to filter usable signals from the echo signals of all measurements after the current measurement command is triggered, thereby calculating the river flow at the flow monitoring point at the time the current measurement command is triggered.

[0033] In actual ADCP measurements, echo signals are not only affected by the hydrological environment but also by the proximity of the lead weight deployment location to the water surface or riverbed. The water surface and riverbed are approximately static boundaries. When the ADCP emits an acoustic signal, the main beam propagates at a set angle, while the sidelobe acoustic waves spread outwards at a larger angle, arriving at the boundary earlier than the main beam and generating echo beams. Ultimately, the echo signal received by the ADCP consists of the superposition of the main beam and the sidelobe beams, resulting in sidelobe interference in the echo signal. This affects the accuracy of subsequent river flow calculations, thus requiring further evaluation.

[0034] Specifically, during normal ADCP measurement, the acquired echo signal exhibits a relatively smooth waveform in the time domain with high regularity, and mainly displays a single-peak shape in the frequency domain. Furthermore, this method is triggered by rapid water level changes, resulting in a fast-flowing water flow, and the normal echo possesses a significant Doppler frequency shift. However, when sidelobe interference occurs, the multiple reflections of the sidelobe beams superimpose with the main beam, causing interference to the waveform of the echo signal in the time domain, resulting in a "double-shoulder" or "plateau" waveform, and a decrease in overall regularity. In the frequency domain, due to the difference in the timing of the superposition of the main beam and sidelobe beams, the overall energy exhibits certain fluctuations. Since the reflections of the sidelobe beams mainly originate from the approximately stationary boundaries of the water surface and riverbed, the overall frequency shift is extremely low, and the echo signal frequency is closer to the frequency of the ADCP-emitted sound wave.

[0035] Based on the above analysis, in order to characterize the sidelobe interference characteristics in the echo signal, the sidelobe interference coefficient of the echo signal during a single measurement can be represented by the waveform morphology and regularity changes in the time domain, as well as the energy changes and frequency differences in the frequency domain. That is, the greater the irregularity of the envelope morphology of the echo signal in the time domain, and the smaller the difference between the overall frequency in the frequency domain and the preset frequency of the transmitted sound wave, the more obvious the sidelobe interference in the current echo signal, and the lower the overall usability of the echo signal.

[0036] To characterize the irregular waveform variations of the echo signals in the time domain during each measurement, the envelopes of the echo signals for each time interval in each measurement process are extracted. The time-to-time (DTW) distance between the envelopes of the echo signals from all adjacent time intervals in each measurement is calculated. The mean of all DTW distances is used as the morphological difference coefficient for each measurement. The larger the value, the greater the difference between the echo signals from adjacent time intervals in each measurement process, and thus the greater the irregularity of the echo signals in each measurement. Furthermore, the total number of peak values ​​in the echo signals of each time interval in each measurement process is counted, and the variance among all the total number of peak values ​​is calculated. The larger the variance, the more irregular the waveform of the echo signals in each measurement.

[0037] Meanwhile, in order to characterize the energy change and frequency difference characteristics of the echo signals in the frequency domain of each measurement, the peak value of the echo signal in the frequency domain for each time interval during a single measurement is obtained, and the frequency value corresponding to each peak value is obtained.

[0038] In a preferred embodiment, a sidelobe interference coefficient is constructed for each measurement based on the waveform differences, peak count differences, and frequency differences between the echo signals and the transmitted signals across all time intervals in each measurement. This coefficient characterizes the degree of sidelobe interference affecting the echo signals in each measurement. The method for constructing the sidelobe interference coefficient is as follows: obtaining the morphological difference coefficient for each measurement; calculating the variance between the total number of peaks in the echo signals across all time intervals in each measurement; calculating the mean between the center frequencies of the echo signals across all time intervals in each measurement, and calculating the absolute difference between the mean and the preset frequency at which the sound wave was transmitted. The sidelobe interference coefficient for each measurement is positively correlated with the morphological difference coefficient and the variance, and negatively correlated with the absolute difference.

[0039] In this embodiment, the sidelobe interference coefficient of the i-th measurement is denoted as... Its specific expression is: In the formula, Let be the sidelobe interference coefficient of the i-th measurement; Let be the morphological difference coefficient for the i-th measurement; Let V be the variance between the total number of peak values ​​in the echo signals across all time intervals in the i-th measurement. Let be the average of the center frequencies of the echo signals across all time intervals in the i-th measurement; The preset frequency for ADCP to emit sound waves (in this embodiment, the preset frequency is 600kHz). This is a preset constant used to prevent the denominator from being 0, and its value ranges from 0.01 to 0.1. In this embodiment, the value is 0.1. For the normalization function, this embodiment uses the minimum-maximum normalization method for normalization. The minimum and maximum values ​​are determined based on the corresponding parameter sets in all measurements after the current measurement command is triggered.

[0040] in, and The larger the value, the more irregular the waveform of the echo signal is during the i-th measurement, and the greater the degree of sidelobe interference it is subjected to. The smaller the value, the smaller the difference between the frequency of the echo signal and the preset frequency during the i-th measurement, and the lower the overall frequency shift. However, this also means that the echo signal experiences greater sidelobe interference during that measurement. In summary, The larger the value, the greater the sidelobe interference of the echo signal in the i-th measurement, and the lower the availability of the echo signal.

[0041] Furthermore, as a preferred embodiment, based on the hydrological interference coefficient and sidelobe interference coefficient of each measurement, a usability coefficient for each measurement is constructed to characterize the usability of the echo signal from each measurement. The usability coefficient for each measurement is negatively correlated with both the hydrological interference coefficient and the sidelobe interference coefficient.

[0042] In this embodiment, the usable coefficient of the i-th measurement is denoted as... Its specific expression is: In the formula, The available coefficients for the i-th measurement; Let be the hydrological interference coefficient for the i-th measurement; Let be the sidelobe interference coefficient of the i-th measurement; This is a preset constant used to prevent the denominator from being zero; For the normalization function, this embodiment uses the minimum-maximum normalization method for normalization. The minimum and maximum values ​​are determined based on the corresponding parameter sets in all measurements after the current measurement command is triggered.

[0043] During a single measurement, the less hydrological interference the echo signal experiences, the less sidelobe interference it receives. The larger the value, the less interference the echo signal is subjected to in the measurement. This means that the echo signal contains more river flow information, has higher availability, and is more accurate in calculating river flow velocity.

[0044] Furthermore, the availability coefficients of all measurements after the current measurement command is triggered are calculated. The echo signal obtained from the measurement process with the largest availability coefficient is recorded as the available signal after the current measurement command is triggered. The lower the degree of river hydrological environment interference and sidelobe interference received by the obtained available signal, the more complete the river flow information it contains, and the higher the accuracy when calculating river flow velocity.

[0045] Calculate the Doppler frequency shift of the available signal at the current flow monitoring point after the current measurement command is triggered; the calculation method for the Doppler frequency shift is a well-known technique, and the specific process will not be elaborated here. Then, calculate the river flow velocity at the current flow monitoring point at the time the measurement command is triggered, using the following formula: In the formula, v is the river flow velocity at the current time the measurement command is triggered; y is the Doppler frequency shift of the available signal at the current time the measurement command is triggered. is the preset frequency for transmitting sound waves; c is the pre-acquired speed of sound in water; The angle between the emitted acoustic beam and the measuring vertical line is 20°-30°, and is 20° in this embodiment.

[0046] Furthermore, the product of the river flow velocity at the current triggering of the measurement command, the pre-determined river profile area, and the preset cross-sectional velocity conversion factor is recorded as the river flow rate at the current triggering of the measurement command. In this embodiment, the preset cross-sectional velocity conversion factor is set to 0.8.

[0047] This completes a bridge flow measurement method based on real-time water level triggering.

[0048] Please see Figure 2 , Figure 2 This is a schematic diagram of a bridge flow measurement device based on real-time water level triggering, provided in an embodiment of this application. In this embodiment, the terminal includes units used to execute the steps in the corresponding embodiment of a bridge flow measurement method based on real-time water level triggering. See also... Figure 2 The bridge-type flow measurement device includes: a data acquisition module, an available signal filtering module, and a flow measurement module.

[0049] The data acquisition module is used to acquire the water level at the flow monitoring point in real time and determine whether a measurement command is triggered. When triggered, it performs multiple measurements and acquires the echo signals from the multiple measurements. The available signal filtering module is used to construct the availability coefficients for each measurement based on the degree of hydrological environmental interference and sidelobe interference of the echo signals of each measurement, thereby filtering out available signals from the echo signals of all measurements after the current measurement command is triggered. The flow measurement module is used to calculate the river flow at the current time the measurement command is triggered, based on available signals.

[0050] Based on the same inventive concept as the above method, this application embodiment also provides a bridge flow measurement system based on real-time water level triggering, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described bridge flow measurement methods based on real-time water level triggering.

[0051] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0052] It should be noted that, unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such article or device. Without further limitations, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0053] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0054] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A bridge flow measurement method based on real-time water level triggering, characterized in that, The method includes the following steps: The system acquires the water level at the flow monitoring point in real time and determines whether a measurement command has been triggered. When triggered, it performs multiple measurements and acquires the echo signals from these measurements. The total duration of echo reception for each measurement is divided into several time intervals. Based on the significance of local peaks, signal strength, bandwidth in the frequency domain, and high-frequency energy attenuation in the echo signals of each measurement, a hydrological interference coefficient for each measurement is constructed to characterize the degree of hydrological interference on the echo signals of each measurement. Based on the waveform differences, peak count differences, and frequency differences between the echo signals and the transmitted signals across all time intervals in each measurement, a sidelobe interference coefficient is constructed for each measurement to characterize the degree of sidelobe interference on the echo signals. Combined with the hydrological interference coefficient, a usable coefficient is constructed for each measurement. This allows us to filter usable signals from the echo signals of all measurements after the current measurement command is triggered, thereby calculating the river flow at the flow monitoring point at the time the current measurement command is triggered.

2. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The specific process for determining whether a measurement command has been triggered is as follows: Calculate the absolute difference between the water level at the current sampling time and the water level at the previous sampling time, and record the ratio of the absolute difference to the water level at the previous sampling time as the water level change rate at the current sampling time; A measurement command is generated when the rate of change of water level at the current sampling time exceeds a preset rate of change threshold, or when the time since the last measurement command is more than a preset trigger time; otherwise, no measurement command is triggered.

3. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The method for constructing the hydrological interference coefficients for each measurement is as follows: The absolute difference between the maximum peak value and the previous adjacent trough value in the echo signal of each measurement is calculated. The ratio of the bandwidth of the echo signal in each measurement to the preset maximum bandwidth is calculated. The amplitude-frequency sequence of the echo signal in each time interval of each measurement is obtained, and the difference between the high-frequency energy in the amplitude-frequency sequence of the echo signal in the first time interval and the last time interval of each measurement is calculated. Calculate the average amplitude of the echo signal from each measurement; The hydrological interference coefficients of each measurement are positively correlated with the absolute difference, the ratio, and the difference, and negatively correlated with the mean amplitude.

4. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The method for constructing the sidelobe interference coefficients for each measurement is as follows: Based on the waveform differences between the echo signals in each time interval of each measurement, the morphological difference coefficient of each measurement is obtained. Calculate the variance among the total number of peak values ​​in the echo signals across all time intervals in each measurement. The mean value of the center frequencies of the echo signals in all time intervals of each measurement is calculated, and the absolute difference between the mean value and the preset frequency when the sound wave is emitted is calculated. The sidelobe interference coefficients of each measurement are positively correlated with the morphological difference coefficients and the variance, and negatively correlated with the absolute difference.

5. The bridge flow measurement method based on real-time water level triggering as described in claim 4, characterized in that, The method for obtaining the morphological difference coefficients for each measurement is as follows: Extract the envelope of the echo signal for each time interval in each measurement; Calculate the DTW distance between the echo signal envelopes of all adjacent time intervals in each measurement, and record the mean of all DTW distances as the morphological difference coefficient for each measurement.

6. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The available coefficients of each measurement are negatively correlated with the hydrological interference coefficient and the sidelobe interference coefficient.

7. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The available signal refers to the echo signal obtained from the measurement process with the largest available coefficient among all measurements after the current measurement command is triggered.

8. The bridge flow measurement method based on real-time water level triggering as described in claim 1, characterized in that, The method for calculating the river flow at the current time when the measurement command is triggered at the flow monitoring point is as follows: Calculate the Doppler frequency shift of the available signal at the current flow monitoring point after the current measurement command is triggered; Calculate the river flow velocity at the current time the measurement command is triggered: In the formula, v is the river flow velocity at the current time the measurement command is triggered; y is the Doppler frequency shift of the available signal at the current time the measurement command is triggered. is the preset frequency for transmitting sound waves; c is the pre-acquired speed of sound in water; The angle between the emitted acoustic beam and the measuring vertical line; The product of the river velocity at the current time the measurement command is triggered, the pre-determined river profile area, and the preset cross-sectional velocity conversion factor is recorded as the river flow at the current time the measurement command is triggered.

9. A bridge-type flow measurement device based on real-time water level triggering, characterized in that, To implement the bridge flow measurement method based on real-time water level triggering as described in any one of claims 1-8, the bridge flow measurement device includes: The data acquisition module is used to acquire the water level at the flow monitoring point in real time and determine whether a measurement command is triggered. When triggered, it performs multiple measurements and acquires the echo signals from the multiple measurements. The available signal filtering module is used to construct the availability coefficients for each measurement based on the degree of hydrological environmental interference and sidelobe interference of the echo signals of each measurement, thereby filtering out available signals from the echo signals of all measurements after the current measurement command is triggered. The flow measurement module is used to calculate the river flow at the current time the measurement command is triggered, based on available signals.

10. A bridge flow measurement system based on real-time water level triggering, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements a bridge flow measurement method based on real-time water level triggering as described in any one of claims 1-8.

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