Self-adaptive metering method of ultrasonic water meter

Abstract

The invention discloses a self-adaptive metering method of an ultrasonic water meter, which relates to the field of water meter metering, and comprises the following steps: acquiring real-time water temperature data and real-time flow velocity data of a measured fluid, compensating the sound velocity of ultrasonic waves based on the real-time water temperature data to obtain a first compensated sound velocity, based on the first compensation sound velocity, an excitation voltage self-adaptive adjustment strategy with ultrasonic wave head-wave ratio regulation and control and a measurement frequency dynamic regulation and control strategy are executed, secondary compensation is conducted through a built error curved surface compensation model with the water temperature and the flow velocity as indexes, and the initial flow value is corrected through an error compensation value; by means of multi-parameter collaborative real-time optimization, high-precision measurement and low-power-consumption operation under all working conditions are achieved, the measurement precision in the full-scale and full-temperature range is remarkably improved, and by intelligently adjusting the measurement frequency, cooperating with the flow rate change rate and error model feedback and dynamically balancing the dynamic response speed and static power consumption, the measurement precision is improved. And finally, double optimization of precision and energy efficiency is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water metering, in particular to an adaptive metering method of an ultrasonic water meter. BACKGROUND

[0002] As a key metering device of modern smart water system, ultrasonic water meter detects the time difference caused by the change of ultrasonic wave speed when it propagates in water, analyzes and processes the flow rate of water and further calculates the flow rate, which has the advantages of low initial flow rate, wide range ratio, high measurement accuracy, stable operation, no moving parts inside, no influence of impurities in water, long service life and so on. However, the existing ultrasonic water meter still faces many technical challenges in practical application: first, the traditional water metering method relies on the time difference method with fixed parameters, which does not fully consider the influence of water temperature change on sound speed, resulting in large fluctuation of metering accuracy under different temperature environments;

[0003] Secondly, the existing system has insufficient adaptability to water quality changes (such as bubbles and impurities), and the signal quality is unstable, which often leads to abnormal first wave ratio, affecting the reliability of time-of-flight detection; thirdly, the fixed frequency measurement strategy cannot balance the accuracy requirement under dynamic working conditions and static power optimization, which easily causes instantaneous flow error when the flow rate suddenly changes, and continuous high frequency measurement leads to unnecessary increase of energy consumption, in addition, the error compensation of existing water meter mostly uses single parameter compensation, which cannot effectively cope with the multi-factor coupling influence caused by transducer performance temperature drift and flow field distribution change due to fluid viscosity change, making it difficult to realize high-precision metering under all working conditions, which seriously restricts the application effect of ultrasonic water meter in smart city drainage system. SUMMARY

[0004] The purpose of the present application is to provide an adaptive metering method of ultrasonic water meter to solve the problems raised in the background.

[0005] To achieve the above purpose, the present application provides the following technical solution: an adaptive metering method of ultrasonic water meter, comprising the following steps:

[0006] Obtaining real-time water temperature data and real-time flow rate data of the measured fluid;

[0007] Compensating the sound speed of ultrasonic wave based on the real-time water temperature data to obtain a first compensated sound speed, and performing an excitation voltage adaptive adjustment strategy with ultrasonic first wave ratio control and a measurement frequency dynamic adjustment strategy based on the first compensated sound speed, so that the ultrasonic water meter maintains optimal metering accuracy and power consumption under different working conditions to calculate the initial flow rate, the excitation voltage adaptive adjustment strategy includes calculating the first wave ratio based on the received ultrasonic receiving signal, dynamically adjusting the excitation voltage applied to the ultrasonic transducer based on the first wave ratio and the real-time water temperature data, so that the first wave ratio is maintained within a preset range;

[0008] Compensate the error surface compensation model indexed by water temperature and flow rate to obtain the corresponding error compensation value, and correct the initial flow value by using the error compensation value to obtain the final flow value.

[0009] As a preferred, the method for dynamically adjusting the excitation voltage applied to the ultrasonic transducer based on the first wave ratio and the real-time water temperature data comprises the following steps:

[0010] Establish a mapping relationship table of water temperature and initial excitation voltage based on historical data, and set a corresponding first wave ratio threshold interval [Rmin, Rmax];

[0011] Use the real-time water temperature data to query the mapping relationship table to determine the initial value of the excitation voltage, and dynamically adjust the excitation voltage according to the relationship between the first wave ratio and the preset first wave ratio threshold interval [Rmin, Rmax] with the initial value of the excitation voltage as the starting point:

[0012] If the first wave ratio is lower than Rmin of the preset first wave ratio threshold interval, the excitation voltage is adjusted to be higher to raise the first wave ratio, and if the first wave ratio is higher than Rmax of the preset first wave ratio threshold interval, the excitation voltage is adjusted to be lower to lower the first wave ratio.

[0013] As a preferred, the measurement frequency dynamic regulation strategy comprises dynamically adjusting the measurement frequency of the ultrasonic water meter based on at least one of the flow rate change rate and the water temperature change rate:

[0014] If the change rate exceeds the respective first threshold value, the measurement frequency is adjusted from the first frequency to the second frequency;

[0015] If the change rate is lower than the respective second threshold value, the measurement frequency is adjusted from the second frequency to the first frequency, and the second frequency is higher than the first frequency.

[0016] As a preferred, the method for constructing the error surface compensation model indexed by water temperature and flow rate comprises the following steps: establishing a plurality of temperature points, collecting actual error values of a plurality of flow rate points at each temperature point to establish a calibration database, storing the calibration database as a three-dimensional lookup table, and performing bilinear interpolation calculation on the three-dimensional lookup table to obtain an error compensation value accurately matched with the current real-time water temperature data and real-time flow rate data.

[0017] As a preferred, the measurement frequency dynamic regulation strategy further comprises accepting the adjustment request issued by the error surface compensation model:

[0018] If the change of the grid node indexed by the error surface compensation model in the compensation calculation of the two adjacent times is greater than a preset node change threshold, a measurement frequency adjustment request is generated;

[0019] The measurement frequency dynamic regulation strategy regulates the measurement frequency in response to the measurement frequency adjustment request.

[0020] As preferred, after the first wave ratio is calculated based on the received ultrasonic wave receiving signal, a first wave ratio reliability judgment is further included, and the specific steps are as follows:

[0021] A reliability threshold based on dynamic adjustment of water temperature and flow rate is set, if the first wave ratio is higher than the reliability threshold, the first wave feature point is used to calculate the time of flight of the ultrasonic wave, if the first wave ratio is lower than the reliability threshold, an anti-interference algorithm is started to calculate the time of flight of the ultrasonic wave.

[0022] As preferred, after the trigger signal loss alarm, the backup signal processing mode is automatically switched to, the historical error compensation value and the real-time water temperature data are used for flow estimation, and after the signal is restored, the main processing mode is gradually switched back to, to ensure the continuity and reliability of metering.

[0023] As preferred, the measurement frequency dynamic regulation strategy further includes temporarily increasing the measurement frequency when the excitation voltage is in the up-regulation stage, to track the optimal voltage point faster, and reducing the measurement frequency when in a stable state to save energy, to realize double energy-saving optimization.

[0024] As preferred, the excitation voltage adaptive adjustment strategy further includes a fault protection step: if the excitation voltage has been up-regulated to a preset upper limit of voltage and the first wave ratio is still continuously lower than a preset lower limit of range, a signal loss alarm is triggered and an abnormal state is recorded.

[0025] As preferred, the adjustment of the excitation voltage includes using an asymptotic adjustment step size, and a voltage adjustment hysteresis interval is set to prevent frequent oscillation near the critical value.

[0026] In summary, the present application has the following advantages:

[0027] The present application realizes high-precision measurement and low-power operation under all working conditions through multi-parameter collaborative real-time optimization: the excitation voltage is dynamically adjusted based on the first wave ratio as the signal quality criterion, to maximize energy efficiency under the premise of ensuring reliability; the measurement precision in the full range and full temperature range is significantly improved through basic compensation of sound speed based on water temperature and advanced compensation based on three-dimensional error surface, and through intelligent adjustment of measurement frequency, the dynamic response speed and static power consumption are dynamically balanced in coordination with the flow rate change rate and error model feedback, to finally achieve dual optimization of precision and energy efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings belong to the protection scope of the present application.

[0029] Figure 1 A flow framework structure schematic diagram of an adaptive metering method of an ultrasonic water meter of the present application;

[0030] Figure 2 A flow framework structure schematic diagram of adaptive adjustment of excitation voltage in the adaptive metering method of the ultrasonic water meter of the present application;

[0031] Figure 3 A flow framework structure schematic diagram of error compensation in the adaptive metering method of the ultrasonic water meter of the present application;

[0032] Figure 4 A flow framework structure schematic diagram of dynamic regulation of measurement frequency in the adaptive metering method of the ultrasonic water meter of the present application. DETAILED DESCRIPTION

[0033] The present application will now be described in further detail with reference to the drawings, obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments, based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application, these drawings are all simplified schematic diagrams, only schematically show the basic structure of the present application, thus only show the relevant constitution of the present application.

[0034] In order to facilitate understanding of the present application, the present application will be described more fully with reference to the relevant drawings, the drawings show several embodiments of the present application, however, the present application can be realized in many different forms, and is not limited to the embodiments described herein, on the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0035] All the features disclosed in this specification, or the steps of all the methods or processes disclosed in this specification, can be combined in any manner, except for the mutually exclusive features and / or steps.

[0036] Any feature disclosed in this specification, unless specifically stated, can be replaced by alternative features or equivalents of the same. That is, each feature is only one example of a range of equivalent or similar features unless specifically stated.

[0037] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can be direct connection, or indirect connection through intermediate medium, can be internal communication of at least two elements or interaction relationship between at least two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] The present application will be described in detail below Figures 1-4 An embodiment of the present application is provided: an adaptive metering method of ultrasonic water meter, based on the principle of ultrasonic time difference method, by monitoring key parameters such as signal quality, water temperature, flow rate, dynamically and intelligently adjusting each link of signal transmission, reception, processing and result correction, mainly composed of five closely linked cores:

[0039] 1. First wave ratio adaptive adjustment: as the "referee" of signal quality, to ensure the reliability of time-of-flight detection;

[0040] 2. Excitation voltage adaptive adjustment strategy with ultrasonic first wave ratio control: as the "regulating valve" of signal strength, to optimize energy consumption under the premise of ensuring reliability;

[0041] 3. Sound velocity water temperature adaptive compensation: to compensate for basic physical quantities and eliminate the influence of water temperature on sound velocity;

[0042] 4. Error curve water temperature and flow rate adaptive compensation: to perform advanced error correction and improve the accuracy under all working conditions to the highest level;

[0043] 5. Measurement frequency dynamic control strategy: the "metronome" of sampling, intelligently balancing dynamic accuracy and static power consumption.

[0044] Specifically as follows:

[0045] Step 1: Initialization and parameter preloading

[0046] After the water meter is powered on, real-time water temperature data and real-time flow rate data of the measured fluid are obtained, and pre-calibrated parameters are loaded from the non-volatile memory, including: "water temperature-sound velocity" corresponding table; "water temperature-initial excitation voltage" query table; "water temperature-flow rate-error" three-dimensional compensation lookup table (LUT) or fitting coefficient set.

[0047] Step 2: Excitation voltage and signal transmission adaptive cycle

[0048] Under the premise of ensuring signal reliability (the first wave ratio is stable in the best interval), dynamically find and maintain a minimum excitation voltage that is sufficient to complete accurate metering, thereby optimizing system power consumption;

[0049] According to the acquired real-time water temperature data T, query the "water temperature-initial voltage table" to set the initial excitation voltage V, and quickly preset the excitation voltage to an initial value that best matches the water temperature, which avoids starting from the absolute minimum value and greatly improves the adjustment efficiency and response speed to changes in working conditions. Transmit ultrasonic waves at the current voltage and receive signals, and calculate the first wave ratio R of this signal.

[0050] It should be noted that the establishment of the "water temperature-initial excitation voltage" query table is as follows: Before the water meter is shipped, through experimental measurement at different water temperatures (such as 5℃, 10℃, 20℃,..., 50℃), the approximate excitation voltage required to achieve the target first wave ratio is measured, because water temperature will affect sound wave attenuation (viscosity change) and transducer efficiency, forming a basic query table.

[0051] Using the calculated first wave ratio R, set a best working interval [Rmin, Rmax] (for example, [0.7, 0.9]) for the first wave ratio R, and make the following judgment and decision:

[0052] Case one: the first wave ratio is too low (R is less than Rmin)

[0053] Judgment: The signal strength is insufficient, the detection risk is high, and the reason may be that the water quality suddenly deteriorates, there are bubbles, or the voltage preset is insufficient.

[0054] Action: Increase the excitation voltage (for example, increase by 1V or 2V stepwise).

[0055] Reverse effect: Enhanced sound wave energy helps to penetrate the medium, making the received signal first wave amplitude increase, thereby directly improving the first wave ratio R and returning it to the normal interval.

[0056] Case two: the first wave ratio is in the best interval (Rmin≤R≤Rmax)

[0057] Judgment: The current state is ideal, and the accuracy and power consumption are balanced.

[0058] Action: Maintain the current excitation voltage unchanged, and the system is at the optimal steady-state working point.

[0059] Case three: the first wave ratio is too high (R is greater than Rmax)

[0060] Judgment: The signal is too strong, energy is wasted, there may be unnecessary resonance or circuit saturation risk, and the power consumption is high.

[0061] Action: Lower the excitation voltage (e.g. decrease step by step with 0.5V or 1V).

[0062] Reverse action: Lowering the emission energy will properly reduce the amplitude of the first wave, thereby reducing the first wave ratio R to return to the normal range, while saving power consumption.

[0063] It is worth mentioning that in this embodiment, the adjustment of the excitation voltage includes using an asymptotic adjustment step, and the voltage adjustment step should not be too large to prevent overshoot from causing oscillation. After adjustment, it needs to be monitored for several measurement periods to confirm the trend is stable before deciding the next action. Hysteresis can be set at the boundary to prevent frequent switching near the critical point. If the excitation voltage has been raised to the upper limit of the preset voltage and the first wave ratio is still below the lower limit of the preset range, a signal loss alarm is triggered and the abnormal state is recorded, forming a fault protection.

[0064] It should be noted that after the trigger signal loss alarm, the system automatically switches to a backup signal processing mode, uses historical error compensation values and real-time water temperature data to estimate the flow rate, and gradually switches back to the main processing mode after the signal is restored, ensuring the continuity and reliability of the metering.

[0065] Step 3: Basic flow calculation and compensation

[0066] Calculate the time of flight: Use the reliable first wave ratio signal to accurately calculate the time of flight t1 and t2 of the forward and reverse flows.

[0067] Sound speed compensation: According to the temperature T, query the "water temperature-sound speed" table to get the accurate sound speed c(T).

[0068] Calculate the original flow rate: Substitute t1, t2, c(T) into the time difference method formula to calculate the original flow rate V and flow rate Q without error compensation.

[0069] Step 4: Advanced error compensation

[0070] Even after sound speed compensation, the measurement error of the ultrasonic water meter is not zero. The root cause is the change of flow field distribution caused by temperature drift of transducer performance, change of fluid viscosity, thermal expansion and contraction of the meter body, etc. Its error characteristics are a three-dimensional error surface with flow rate (V) as X-axis and error (δ) as Y-axis, which changes with water temperature (T). Therefore, a three-dimensional error surface compensation model indexed by water temperature and flow rate is established. Through software algorithm, real-time compensation is performed on the three-dimensional error surface to converge the error of the water meter within the full range and full temperature range to the highest accuracy level (such as ±1% or higher).

[0071] It should be noted that in this embodiment, the three-dimensional error surface compensation model indexed by water temperature and flow rate includes the following steps:

[0072] High-precision calibration: Place the water meter on the flow standard device, at multiple temperature points (such as T=[5℃, 10℃, 20℃, 30℃, 40℃, 50℃]), collect multiple flow rate points (such as V=[low flow rate, 0.5Q, Q, 1.5Q, high flow rate], Q is the normal flow rate) at each temperature point, and collect the actual error value δ(T, V).

[0073] Construct error matrix (database): Store the calibration data as a three-dimensional look-up table (LUT). This essentially builds an error surface model indexed by T and V.

[0074] For example, one of the storage methods is as follows:

[0075] Water temperature (T) Flow rate (V) Error compensation value (δ) 5℃ 0.01 m / s +2.5% 5℃ 0.1 m / s +1.8% ... ... ... 20℃ 0.01 m / s +1.0% 20℃ 0.1 m / s +0.5% ... ... ... 50℃ 0.01 m / s -0.8% 50℃ 0.1 m / s -1.2%

[0076] To save memory space, the error curve at each temperature point can also be fitted by a formula. For example, using quadratic curve fitting: δ(T, V)=a(T) * V² + b(T) * V + c(T), only the coefficient set [a_i, b_i, c_i] corresponding to each temperature T_i needs to be stored.

[0077] When performing compensation:

[0078] Get real-time values: Get the current accurate real-time water temperature data T and real-time flow rate data V.

[0079] Table lookup and interpolation: Index by (T, V) in the three-dimensional error LUT to perform bilinear interpolation to get the error compensation value δ at this point, as follows:

[0080] Two-dimensional table lookup: In the stored error matrix, find the four nearest neighbor nodes that surround the (T, V) point: (T_low, V_low), (T_low, V_high), (T_high, V_low), (T_high, V_high).

[0081] Bilinear interpolation: Use the error values δ(T_low, V_low), δ(T_low, V_high), δ(T_high, V_low), δ(T_high, V_high) of the four nodes to calculate the accurate error compensation value δ required for the current (T, V) point by bilinear interpolation algorithm.

[0082] Formula calculation: If the fitting formula is used, first determine the interval to which the current temperature real-time water temperature data T belongs, obtain the coefficients of the adjacent two temperature points, perform interpolation to obtain the coefficients a(T), b(T), and c(T) of the current temperature, and then substitute the real-time flow rate data V to calculate δ.

[0083] Final output: Calculate the final flow rate: Q1=Q*(1-δ / 100), which is the high-precision result after full-link compensation.

[0084] Fifth step: Global adaptive coordination of measurement frequency

[0085] The measurement frequency refers to the number of complete ultrasonic measurements performed by the water meter per second or per minute. Fixed high-frequency measurement under steady-state flow can lead to unnecessary power consumption, while fixed low-frequency measurement may not accurately capture dynamic processes when the flow rate changes, resulting in low instantaneous flow accuracy and total cumulative error.

[0086] This process is independent of a loop that continuously monitors the flow rate change rate (dV / dt) and the water temperature change rate (dT / dt), while each sets a corresponding safety threshold. Once the change rate exceeds the safety threshold, the measurement frequency is adjusted from the first frequency to the second frequency, the measurement frequency is increased, and the second step is shortened to ensure that high-granularity data is provided for the fourth step to capture dynamic processes and accurately capture the dynamic details of the flow rate, improving the accuracy of the instantaneous flow rate and the accuracy of the total cumulative error.

[0087] If it is below the safety threshold, the measurement frequency is adjusted from the second frequency to the first frequency, the second frequency is higher than the first frequency, the measurement frequency is reduced, the period of the second step is extended, and the low-power sleep state is entered until the next measurement or is awakened.

[0088] It is worth mentioning that in this embodiment, if the excitation voltage is in the voltage up-regulation phase during measurement, the measurement frequency can be temporarily increased to track the optimal voltage point faster; when the system is in a stable state, the measurement frequency can be reduced to save energy, achieving double energy-saving optimization and forming a synergy with the second step.

[0089] It should be noted that in this embodiment, the measurement frequency dynamic adjustment strategy also includes accepting adjustment requests from the error surface compensation model, specifically, when in the steady-state low-frequency measurement mode, the error compensation itself can act as a "listener", which can record the current index position and interpolation distance at each interpolation calculation;

[0090] If it is detected that the indexed LUT grid node of the two adjacent compensation calculations has a jump (for example, suddenly jumps from the (20℃, 0.1m / s) node to the (20℃, 0.5m / s) node), it means that the flow rate may be changing dramatically, but the measurement frequency has not yet captured it, at this time, the error compensation module can send a "request to increase the sampling rate" signal to the measurement frequency controller, and the measurement frequency controller can immediately or gradually increase the frequency after receiving the signal to verify and respond to the change, which provides a novel criterion for measurement frequency adjustment based on software algorithm, enabling it to make decisions based on not only simple hardware signals (such as first wave ratio) or raw physical quantity change rate (dV / dt), but also higher-level application logic (compensation algorithm state), becoming more intelligent and forward-looking, further optimizing the "precision-power consumption" balance.

[0091] It is also worth mentioning that in the present embodiment, after calculating the first wave ratio from the received ultrasonic wave receiving signal, a first wave ratio reliability judgment is also included. In actual applications, water quality changes (such as bubbles, impurities), pipe inner wall scaling, transducer surface contamination, or water temperature changes can all cause ultrasonic signal attenuation, first wave amplitude reduction, and even make subsequent reflected waves or noise waves become the largest wave, resulting in ToF capture errors and large measurement errors, so it is necessary to perform a reliability judgment on the first wave ratio.

[0092] The first wave refers to the first peak of the ultrasonic wave signal detected by the receiving transducer.

[0093] The first wave ratio refers to the ratio of the first wave amplitude to the amplitude of a subsequent reference wave. A high first wave ratio usually means a strong signal, less interference, clean waveform, and more accurate and reliable Time of Flight (ToF) capture point.

[0094] A first wave ratio reliability threshold is set. If the first wave ratio is higher than the reliability threshold, the signal quality is considered excellent, and the zero-crossing point or characteristic point of the first wave is directly used as the ToF calculation reference, with the highest accuracy. If the first wave ratio is lower than the reliability threshold, the signal quality is considered poor, and there is interference. In this case, the system does not simply use the first wave, but activates a backup algorithm, for example:

[0095] The cross-correlation algorithm is used to calculate the similarity between the transmitted signal and the received signal to determine the ToF based on the peak position. This method has strong anti-interference ability but has a large amount of calculation.

[0096] The position information of the maximum wave and the first wave is combined for comprehensive judgment, or digital filtering is used to purify the signal.

[0097] In summary, the present application converts the ultrasonic water meter from a passive, parameter-fixed measuring device to an active, self-optimizing intelligent metering terminal through multi-parameter sensing, closed-loop feedback, and cross-layer linkage, achieving comprehensive optimization of the three core indicators of "precision, power consumption, and reliability" under all operating conditions.

[0098] The specific advantages are as follows:

[0099] Extremely high full-condition measurement accuracy:

[0100] Multi-dimensional error compensation: not only basic sound speed and water temperature compensation, but also advanced three-dimensional error surface compensation model indexed by water temperature and flow rate. This can accurately correct nonlinear errors caused by transducer temperature drift, fluid viscosity changes, and meter body deformation, etc., and improve the accuracy of the water meter to the highest level (such as ±1%) in the full range and full temperature range.

[0101] Excellent low power consumption performance and energy efficiency optimization:

[0102] Dynamic optimization of excitation voltage: instead of using a fixed high voltage, a minimum effective excitation voltage is dynamically found and maintained under the premise of ensuring signal reliability, which significantly reduces the power consumption of the ultrasonic transducer, the main energy-consuming unit.

[0103] Intelligent adjustment of measurement frequency: dynamically adjust the sampling frequency according to the rate of change of flow rate and water temperature. In the low-frequency sleep mode to save power in steady flow, and quickly switch to high-frequency mode to maintain accuracy in dynamic flow. Achieve "static deep energy saving, dynamic accurate capture".

[0104] Dual energy-saving synergy: excitation voltage adjustment and measurement frequency adjustment interact with each other (such as temporarily increasing the frequency when adjusting the voltage), forming a synergistic energy-saving effect, further optimizing the overall energy efficiency.

[0105] Strong environmental adaptability and reliability:

[0106] First wave ratio as the core criterion: using the first wave ratio as the "referee" of signal quality, it can effectively deal with on-site complex factors such as water quality changes (bubbles, impurities), pipe scaling, and transducer contamination, ensuring the reliability of time-of-flight detection.

[0107] Intelligent fault-tolerant algorithm: when the first wave ratio is too low, instead of directly using the possibly incorrect first wave, the algorithm starts the backup algorithm such as cross-correlation to calculate, ensuring that the metering function can still be used under harsh conditions without large errors.

[0108] Hysteresis and asymptotic adjustment: the voltage adjustment uses asymptotic step size and hysteresis interval to prevent oscillation and frequent switching near the critical point, enhancing the stability and robustness of the system.

[0109] Fast system response and convergence speed:

[0110] Initial voltage lookup table: Quickly preset an excitation voltage starting point close to the optimal value based on water temperature, avoiding the long "trial and error" process of starting from the absolute minimum value, and greatly improving the response speed and adjustment efficiency to changes in operating conditions.

[0111] Advanced intelligence and forward-looking decision-making:

[0112] Application-layer-based intelligent triggering: This is a very novel aspect of this method. The adjustment of the measurement frequency can be based not only on hardware signals (first-wave ratio) or the rate of change of physical quantities (dV / dt), but also on requests from the error compensation module. When the compensation algorithm detects a "jump" in the error matrix, it can anticipate the change and request an increase in the sampling rate, achieving a higher level of more proactive intelligent control and further optimizing the balance between accuracy and power consumption.

[0113] In practical operation, consider a household user turning on their shower in the morning. Initially, the water in the pipes is cold, and then hot water is gradually poured in from the solar water heater, causing significant changes in both water flow rate and temperature. The water meter needs to maintain high-precision metering throughout this dynamic process.

[0114] Initial state: water temperature T=20℃, flow velocity V=0.1 m / s (micro-flow), the system is in steady-state low-power mode.

[0115] Event: The user turns on the shower valve.

[0116] Change process: The flow rate rises sharply to 1.5 m / s within 3 seconds, while the water temperature slowly rises from 20℃ to 35℃ over the next 30 seconds, and finally stabilizes.

[0117] Adaptive system operation process and data recording

[0118] We will present the system's behavior and changes in key internal parameters at each stage in the form of a time series.

[0119] t=0, initial steady state;

[0120] R=0.85 (excellent), excitation voltage 12V, sound velocity c=1482.8 m / s, from table: δ=+0.8%, measurement frequency is 1Hz (low frequency);

[0121] At t=1, the flow velocity begins to surge (dV / dt, increases dramatically);

[0122] R=0.83 (still good), maintain 12V, sound speed c=1482.8 m / s, linkage: detected excessive dV / dt, immediately trigger high frequency mode: 8Hz (high frequency);

[0123] t=1.1;

[0124] Flow rate V=0.8 m / s, R=0.9 (signal strong), signal too strong, gradually reduce the voltage, sound speed c=1482.8 m / s, look up table + interpolation: delta = +0.2%, maintain 8Hz;

[0125] t=1.2;

[0126] Flow rate V=1.5 m / s, R=0.92, excitation voltage reduced to 10V, sound speed c=1482.8 m / s, look up table: delta = -0.5%, maintain 8Hz;

[0127] t=10, water temperature starts to rise;

[0128] T=25℃, V=1.5 m / s, R=0.88, maintain 10V, sound speed c=1496.7 m / s, when calculating the compensation value, find that the temperature index jumps from 20℃ to 25℃, send "temperature change warning" in reverse, confirm that dT / dt becomes large, maintain high frequency mode, maintain 8Hz;

[0129] t=20;

[0130] T=30℃, V=1.5 m / s, R=0.87, according to T=30℃ query voltage table, fine-tune excitation voltage to 9.5V, sound speed c=1509.5 m / s, look up table: delta = -1.0%, maintain 8Hz;

[0131] t=40, enter new steady state;

[0132] T=35℃, V=1.5 m / s, R=0.86 (stable), excitation voltage 9.5V (stable), sound speed c=1521.1 m / s, look up table: delta = -1.3%, decision: dV / dt and dT / dt both tend to 0, gradually reduce frequency.

[0133] t=50, stable flow;

[0134] R=0.86, excitation voltage 9.5V (stable), sound speed c=1521.1 m / s, delta = -1.3%, frequency reduced to 2Hz (medium frequency, energy saving and accuracy).

[0135] Dynamic response and linkage (t=1s):

[0136] Frequency adaptation as a pioneer, first detects the sharp change of flow rate (dV / dt) through hardware, immediately raises the measurement frequency from 1Hz to 8Hz. This provides a high-precision instantaneous data source for all subsequent technical points, which is the premise to ensure that the entire system keeps up with changes.

[0137] Energy optimization (t=1.1s - t=1.2s):

[0138] After the flow rate is increased, the signal transmission condition is improved, and the first wave ratio R is increased.

[0139] The first wave ratio self-adaptively feeds back the high-quality R value to the excitation voltage self-adaptation.

[0140] Accordingly, the excitation voltage self-adaptation makes a decision to reduce the excitation voltage from 12V to 10V, which realizes energy saving while ensuring signal quality.

[0141] Advanced compensation and intelligent feedback (t=10s):

[0142] The sound velocity compensation always provides an accurate sound velocity value c(T) to complete the basic compensation.

[0143] The error compensation is the core of accuracy. It uses the accurate (T, V) data brought by high-frequency measurement to perform real-time table lookup and interpolation compensation. For example, at the point of (35℃, 1.5m / s), it compensates an error of -1.3%.

[0144] Key linkage: When the error compensation finds that the water temperature index changes during calculation, it sends a warning to the frequency self-adaptation in the opposite direction, which consolidates the decision to maintain high-frequency measurement. This reflects the intelligent guidance of the algorithm layer to the system control layer.

[0145] Steady-state optimization (t=40s - t=50s):

[0146] When the system enters a new steady state, the frequency self-adaptation again plays a role in reducing the measurement frequency from 8Hz for high performance to 2Hz for balanced power consumption and accuracy, reflecting the energy-saving awareness of the system.

[0147] The above is only a specific implementation of the invention, but the protection scope of the invention is not limited to this. Any changes or substitutions without creative labor should be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be limited to the protection scope defined in the claims.

Claims

1. An adaptive metering method for an ultrasonic water meter, characterized by: The method comprises the following steps: acquiring real-time water temperature data and real-time flow rate data of a measuring fluid; compensating the sound speed of ultrasonic waves based on the real-time water temperature data to obtain a first compensated sound speed, and performing an excitation voltage adaptive adjustment strategy with ultrasonic first wave ratio control and a measurement frequency dynamic adjustment strategy based on the first compensated sound speed, so that an ultrasonic water meter maintains optimal metering accuracy and power consumption under different working conditions to calculate an initial flow value, the excitation voltage adaptive adjustment strategy comprising receiving an ultrasonic receiving signal to calculate a first wave ratio, dynamically adjusting the excitation voltage applied to an ultrasonic transducer based on the first wave ratio and the real-time water temperature data, so that the first wave ratio is maintained within a preset range; performing secondary compensation using a constructed error surface compensation model indexed by water temperature and flow rate, inputting the real-time water temperature data and the real-time flow rate data to obtain a corresponding error compensation value, and correcting the initial flow value using the error compensation value to obtain a final flow value.

2. The self-adapting metering method of an ultrasonic water meter according to claim 1, characterized in that: The method for dynamically adjusting the excitation voltage applied to the ultrasonic transducer based on the first wave ratio and the real-time water temperature data comprises the following steps: establishing a mapping relationship table of water temperature and initial excitation voltage based on historical data, and setting a corresponding first wave ratio threshold interval [Rmin, Rmax]; using the real-time water temperature data to query the mapping relationship table to determine the initial value of the excitation voltage, and dynamically adjusting the excitation voltage based on the relationship between the first wave ratio and the preset first wave ratio threshold interval [Rmin, Rmax] with the initial value of the excitation voltage as the starting point: if the first wave ratio is lower than Rmin of the preset first wave ratio threshold interval, the excitation voltage is adjusted to be higher to raise the first wave ratio, and if the first wave ratio is higher than Rmax of the preset first wave ratio threshold interval, the excitation voltage is adjusted to be lower to lower the first wave ratio.

3. The self-adapting metering method of an ultrasonic water meter according to claim 2, characterized in that: The measurement frequency dynamic adjustment strategy comprises dynamically adjusting the measurement frequency of the ultrasonic water meter based on at least one of the flow rate change rate and the water temperature change rate: if the change rate exceeds the respective first threshold value, the measurement frequency is adjusted from a first frequency to a second frequency; if the change rate is lower than the respective second threshold value, the measurement frequency is adjusted from the second frequency to the first frequency, and the second frequency is higher than the first frequency.

4. The self-adapting metering method of an ultrasonic water meter according to claim 3, wherein: The method for constructing the error surface compensation model indexed by water temperature and flow rate comprises the following steps: establishing a plurality of temperature points, collecting actual error values of a plurality of flow rate points at each temperature point to establish a calibration database, storing the calibration database as a three-dimensional lookup table, and performing bilinear interpolation calculation on the three-dimensional lookup table to obtain an error compensation value accurately matched with the current real-time water temperature data and real-time flow rate data.

5. An adaptive metering method for an ultrasonic water meter according to claim 4, characterized in that: The measurement frequency dynamic adjustment strategy further comprises accepting an adjustment request issued by the error surface compensation model: real-time detection of the change of the grid node indexed by the error surface compensation model in the compensation calculation of the adjacent two times exceeding a preset node change threshold value generates a measurement frequency adjustment request; the measurement frequency dynamic adjustment strategy responds to the measurement frequency adjustment request to adjust the measurement frequency.

6. An adaptive metering method for an ultrasonic water meter according to claim 5, characterized in that: After calculating the first wave ratio of the received ultrasonic wave receiving signal, a first wave ratio reliability judgment is further included, and the specific steps are as follows: A reliability threshold based on water temperature and flow rate dynamic adjustment is set, if the first wave ratio is higher than the reliability threshold, the first wave feature point is used to calculate the flight time of the ultrasonic wave; if the first wave ratio is lower than the reliability threshold, an anti-interference algorithm is started to calculate the flight time of the ultrasonic wave.

7. An adaptive metering method for an ultrasonic water meter according to claim 6, characterized in that: The excitation voltage adaptive adjustment strategy further includes a fault protection step: if the excitation voltage has been adjusted to the upper limit of the preset voltage and the first wave ratio is still continuously lower than the lower limit of the preset range, a signal loss alarm is triggered and an abnormal state is recorded.

8. The self-adapting metering method of an ultrasonic water meter according to claim 7, characterized in that: The adjustment of the excitation voltage includes using an asymptotic adjustment step size, and a voltage adjustment hysteresis interval is provided to prevent frequent oscillation near the critical value.

9. An adaptive metering method for an ultrasonic water meter according to claim 8, characterized in that: After the trigger signal loss alarm, the system automatically switches to a backup signal processing mode, uses historical error compensation values and real-time water temperature data to estimate the flow rate, and gradually switches back to the main processing mode after the signal is restored, ensuring the continuity and reliability of the metering.

10. The self-adapting metering method of an ultrasonic water meter according to claim 9, wherein: The measurement frequency dynamic regulation strategy further includes temporarily increasing the measurement frequency when the excitation voltage is in the up-regulation stage to quickly track the optimal voltage point, and reducing the measurement frequency when in the stable state to save energy, achieving double energy-saving optimization.

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