An adaptive metering method for an ultrasonic water meter

Abstract

The application discloses a kind of self-adapting metering methods of ultrasonic water meter, it is related to water meter measurement field, comprising the following steps, obtain the real-time water temperature data and real-time flow rate data of measured fluid, the sound velocity of ultrasonic wave is compensated based on real-time water temperature data, obtain first compensation sound velocity, and based on first compensation sound velocity, execute the excitation voltage self-adapting adjustment strategy with the measurement frequency dynamic control strategy with the first wave ratio control of ultrasonic wave, utilize the error surface compensation model indexed with water temperature and flow rate constructed to carry out secondary compensation, and utilize error compensation value to correct initial flow value, the application realizes high-precision measurement and low-power operation in full operating condition by multi-parameter collaborative real-time optimization, significantly improve the measurement accuracy of full range, full temperature range, by intelligent adjustment measurement frequency, collaborative flow rate change rate and error model feedback, dynamic balance dynamic response speed and static power consumption, finally achieve the dual optimization of precision and energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of water meter measurement, specifically to an adaptive metering method for ultrasonic water meters. Background Technology

[0002] Ultrasonic water meters, as key metering devices in modern smart water systems, detect the time difference caused by the velocity change of ultrasonic beams propagating in water upstream and downstream, analyze and process the data to determine the water velocity, and further calculate the flow rate. They offer significant advantages such as low starting velocity, wide rangeability, high measurement accuracy, stable operation, no internal moving parts, immunity to impurities in the water, and long service life. However, existing ultrasonic water meters still face several technical challenges in practical applications: First, traditional water metering methods rely on time-difference calculations with fixed parameters, failing to fully consider the impact of water temperature changes on the velocity of sound, resulting in significant fluctuations in metering accuracy under different temperature conditions.

[0003] Secondly, existing systems are not adaptable enough to changes in water quality (such as the presence of air bubbles and impurities), resulting in unstable signal quality and often causing abnormal first-wave ratios, which affects the reliability of time-of-flight detection. Furthermore, fixed-frequency measurement strategies cannot simultaneously meet the accuracy requirements under dynamic operating conditions and optimize static power consumption. They are prone to instantaneous flow errors when the flow velocity changes abruptly, while continuous high-frequency measurement leads to unnecessary energy consumption increases. In addition, existing water meter error compensation mostly uses single-parameter compensation, which cannot effectively cope with the coupled effects of multiple factors such as transducer performance temperature drift and changes in flow field distribution caused by fluid viscosity changes. It is difficult to achieve high-precision metering under all operating conditions. These technical bottlenecks seriously restrict the application effect of ultrasonic water meters in smart city drainage systems. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive metering method for ultrasonic water meters to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an adaptive metering method for an ultrasonic water meter, comprising the following steps:

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

[0007] The ultrasonic velocity is compensated based on the real-time water temperature data to obtain a first compensated velocity. Based on the first compensated velocity, an adaptive adjustment strategy for excitation voltage with ultrasonic first wave ratio control and a dynamic adjustment strategy for measurement frequency are executed to enable the ultrasonic water meter to maintain optimal metering accuracy and power consumption under different operating conditions for calculating the initial flow value. The adaptive adjustment strategy for excitation voltage includes receiving the ultrasonic receiving signal to calculate the first wave ratio, and dynamically adjusting the excitation voltage applied to the ultrasonic transducer based on the first wave ratio and the real-time water temperature data to keep the first wave ratio within a preset range.

[0008] Secondary compensation is performed using the constructed error surface compensation model indexed by water temperature and flow velocity. The real-time water temperature data and the real-time flow velocity data are input to obtain the corresponding error compensation value. The initial flow value is then corrected using the error compensation value to obtain the final flow value.

[0009] Preferably, 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 includes the following steps:

[0010] A mapping table between water temperature and initial excitation voltage was established based on historical data, and the corresponding first-wave ratio threshold range [Rmin, Rmax] was set.

[0011] The initial value of the excitation voltage is determined by querying the mapping table using the real-time water temperature data. Starting from the initial value of the excitation voltage, the excitation voltage is dynamically adjusted according to the relationship between the first wave ratio and the preset first wave ratio threshold range [Rmin, Rmax].

[0012] If the first wave ratio is lower than Rmin of the preset first wave ratio threshold range, the excitation voltage is increased to raise the first wave ratio. If the first wave ratio is higher than Rmax of the preset first wave ratio threshold range, the excitation voltage is decreased to lower the first wave ratio.

[0013] Preferably, the dynamic control strategy for the measurement frequency includes dynamically adjusting the measurement frequency of the ultrasonic water meter based on at least one of the rate of change of flow velocity and the rate of change of water temperature.

[0014] If the rate of change exceeds the corresponding first threshold, the measurement frequency will be adjusted from the first frequency to the second frequency.

[0015] If the rate of change is lower than the corresponding second threshold, the measurement frequency is adjusted from the second frequency to the first frequency, where the second frequency is higher than the first frequency.

[0016] Preferably, the method for constructing an error surface compensation model indexed by water temperature and flow velocity includes the following steps: establishing multiple temperature points, collecting actual error values ​​of several flow velocity 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 error compensation values ​​that accurately match the current real-time water temperature data and real-time flow velocity data.

[0017] Preferably, the dynamic control strategy for the measurement frequency also includes accepting adjustment requests from the error surface compensation model:

[0018] If the change in the grid nodes indexed by the error surface compensation model in two consecutive compensation calculations exceeds a preset node change threshold in real time, a measurement frequency adjustment request is generated.

[0019] The dynamic control strategy for measurement frequency responds to the measurement frequency adjustment request by adjusting the measurement frequency.

[0020] Preferably, after calculating the first wave ratio from the received ultrasonic signal, the method also includes a first wave ratio reliability assessment, with the specific steps as follows:

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

[0022] Preferably, after the trigger signal is lost and an alarm is triggered, the system automatically switches to the 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 to ensure the continuity and reliability of metering.

[0023] Preferably, the dynamic measurement frequency control strategy also includes temporarily increasing the measurement frequency when the excitation voltage is in the upward adjustment phase to track the optimal voltage point more quickly, and reducing the measurement frequency when it is in a stable state to save energy, thus achieving dual energy-saving optimization.

[0024] Preferably, the excitation voltage adaptive adjustment strategy further includes a fault protection step: if the excitation voltage has been increased to the preset voltage upper limit and the first wave ratio is still lower than the preset range lower limit, then a signal loss alarm is triggered and the abnormal state is recorded.

[0025] Preferably, the adjustment of the excitation voltage includes a gradual adjustment step size and a voltage adjustment hysteresis range to prevent frequent oscillations near the critical value.

[0026] In summary, the beneficial effects of this invention are:

[0027] This invention achieves high-precision measurement and low-power operation under all working conditions through multi-parameter collaborative real-time optimization: the excitation voltage is dynamically adjusted using the first wave ratio as the signal quality criterion to maximize energy efficiency while ensuring reliability; combined with basic compensation for sound velocity based on water temperature and advanced compensation based on three-dimensional error surface, the measurement accuracy across the entire range and temperature range is significantly improved; by intelligently adjusting the measurement frequency and coordinating the flow rate change rate with error model feedback, the dynamic response speed and static power consumption are dynamically balanced, ultimately achieving dual optimization of accuracy and energy efficiency. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the invention 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 the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the process framework of an adaptive metering method for an ultrasonic water meter according to the present invention.

[0030] Figure 2 This is a schematic diagram of the process framework for adaptive adjustment of excitation voltage in an adaptive metering method for an ultrasonic water meter according to the present invention.

[0031] Figure 3 This is a schematic diagram of the error compensation process in the adaptive metering method for an ultrasonic water meter according to the present invention.

[0032] Figure 4 This is a schematic diagram of the process framework for dynamic adjustment of measurement frequency in the adaptive metering method of an ultrasonic water meter according to the present invention. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0034] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

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

[0036] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of at least two elements or the interaction relationship of at least two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] The following is combined with Figures 1-4 This invention provides a detailed description of one embodiment: an adaptive metering method for ultrasonic water meters, based on the principle of ultrasonic time-of-flight measurement. By real-time monitoring of key parameters such as signal quality, water temperature, and flow rate, it dynamically and intelligently adjusts each stage of signal transmission, reception, processing, and result correction. It mainly consists of five closely linked core components:

[0039] 1. Adaptive adjustment of first wave ratio: As the "judge" of signal quality, it ensures the reliability of time-of-flight detection;

[0040] 2. An adaptive adjustment strategy for excitation voltage with ultrasonic first wave ratio regulation: acting as a "regulating valve" for signal strength, optimizing energy consumption while ensuring reliability;

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

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

[0043] 5. Dynamic frequency control strategy: The sampling "metronome" intelligently balances 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, it acquires real-time water temperature data and real-time flow velocity data of the measured fluid, and loads pre-calibrated parameters from non-volatile memory, including: a "water temperature-velocity of sound" correspondence table; a "water temperature-initial excitation voltage" lookup table; and a "water temperature-flow velocity-error" three-dimensional compensation lookup table (LUT) or a set of fitting coefficients.

[0047] Step 2: Adaptive loop of excitation voltage and signal transmission

[0048] While ensuring signal reliability (the first wave ratio is stable within the optimal range), the system dynamically seeks and maintains a minimum excitation voltage sufficient for accurate measurement, thereby optimizing system power consumption.

[0049] Based on the real-time water temperature data T, the "Water Temperature-Initial Voltage Meter" is queried, and the initial value of the excitation voltage V is set. The excitation voltage is quickly preset to an initial value that best matches the water temperature. This avoids the need to start from the absolute minimum value and greatly improves the adjustment efficiency and response speed to changes in operating conditions. Ultrasonic waves are emitted with the current voltage and the signal is received. The first wave ratio R of this signal is calculated.

[0050] It should be noted that the establishment of the "water temperature-initial excitation voltage" lookup table is as follows: before the water meter leaves the factory, the approximate excitation voltage required to achieve the target first wave ratio is measured experimentally at different water temperatures (such as 5℃, 10℃, 20℃, ..., 50℃). This is because water temperature affects sound wave attenuation (viscosity change) and transducer efficiency, forming a basic lookup table.

[0051] Using the calculated first wave ratio R, and setting an optimal working range for the first wave ratio R [Rmin, Rmax] (e.g., [0.7, 0.9]), the following decision-making process is performed:

[0052] Scenario 1: The initial wave ratio is too low (R is less than Rmin).

[0053] Judgment: Insufficient signal strength indicates a high detection risk. Possible causes include a sudden deterioration in water quality, the presence of air bubbles, or insufficient voltage preset.

[0054] Action: Increase the excitation voltage (e.g., by increasing it in steps of 1V or 2V).

[0055] Reverse effect: The enhanced acoustic energy helps penetrate the medium, increasing the amplitude of the first wave of the received signal, thereby directly increasing the first wave ratio R and bringing it back to the normal range.

[0056] Scenario 2: The first wave ratio is in the optimal range (Rmin≤R≤Rmax).

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

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

[0059] Scenario 3: The initial wave ratio is too high (R > Rmax).

[0060] Judgment: The signal is too strong, which wastes energy and may pose a risk of unnecessary resonance or circuit saturation. In addition, the power consumption is too high.

[0061] Action: Reduce the excitation voltage (e.g., decrease it in steps of 0.5V or 1V).

[0062] Reverse effect: Reducing the transmission energy will appropriately reduce the amplitude of the first wave, thereby reducing the first wave ratio R and bringing it back to the normal range, while saving power consumption.

[0063] It is worth mentioning that, in this embodiment, the adjustment of the excitation voltage includes the use of a gradual adjustment step size. The voltage adjustment step size should not be too large to prevent overshoot and oscillation. After adjustment, it is necessary to continuously monitor several measurement cycles to confirm that the trend is stable before deciding on the next action. Hysteresis can be set at the interval boundary to prevent frequent switching near the critical point. If the excitation voltage has been increased to the preset voltage upper limit and the first wave ratio is still lower than the preset range lower limit, a signal loss alarm is triggered and the abnormal state is recorded to form fault protection.

[0064] It should be noted that after the trigger signal is lost and an alarm is triggered, the system automatically switches to the backup signal processing mode, using historical error compensation values ​​and real-time water temperature data for flow estimation. Once the signal is restored, it gradually switches back to the main processing mode to ensure metering continuity and reliability.

[0065] Step 3: Basic Flow Calculation and Compensation

[0066] Calculate flight time: Using a more reliable signal than the first wave, accurately calculate the flight times t1 and t2 for downstream and upstream currents.

[0067] Sound speed compensation: The accurate sound speed c(T) is obtained by looking up the "water temperature-sound speed" table based on the temperature T.

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

[0069] Step 4: Advanced Error Compensation

[0070] Even with sound velocity compensation, the measurement error of ultrasonic water meters is still non-zero. The root cause lies in the temperature drift of the transducer performance, the change in flow field distribution caused by changes in fluid viscosity, and the thermal expansion and contraction of the meter body. Moreover, its error characteristics are manifested as a three-dimensional error surface with flow velocity (V) as the X-axis and error (δ) as the Y-axis, which varies with water temperature (T). Based on this, a supplementary model of the three-dimensional error surface is established with water temperature and flow velocity as indexes. Through software algorithms, this three-dimensional error surface is compensated in real time, and the error of the water meter in the full range and temperature range is converged to the highest accuracy level (such as ±1% or higher).

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

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

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

[0074] For example, one storage method 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 for each temperature point can also be fitted using a formula. For example, a quadratic curve fitting can be used: δ(T, V)=a(T) * V² + b(T) * V + c(T), which only requires storing the coefficient set [a_i, b_i, c_i] corresponding to each temperature T_i.

[0077] When making compensation:

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

[0079] Lookup table and interpolation: Using (T,V) as the index, perform bilinear interpolation in the three-dimensional error LUT to obtain the error compensation value δ for that point, as follows:

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

[0081] Bilinear interpolation: Using the error values ​​δ(T_low, V_low), δ(T_low, V_high), δ(T_high, V_low), δ(T_high, V_high) of these four nodes, the precise error compensation value δ required for the current (T,V) point is calculated using the bilinear interpolation algorithm.

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

[0083] Final output: Calculate the final flow: Q1=Q* (1-δ / 100), this value is the high-precision result after end-to-end compensation.

[0084] Step 5: Global adaptive coordination of measurement frequency

[0085] Measurement frequency refers to how many complete ultrasonic measurements the water meter performs per second or per minute. Fixed high-frequency measurement can lead to unnecessary power consumption under steady-state flow; fixed low-frequency measurement will fail to accurately capture dynamic processes when the flow velocity changes abruptly, resulting in low instantaneous flow accuracy and cumulative total error.

[0086] This process operates in a separate loop, continuously monitoring the rate of change of flow velocity (dV / dt) and the rate of change of water temperature (dT / dt), while setting corresponding safety thresholds for each. Once the rate of change exceeds the safety threshold, the measurement frequency is adjusted from the first frequency to the second frequency, increasing the measurement frequency and shortening the cycle to the second step. This ensures that high-granularity data is provided for the fourth step, capturing the dynamic process and accurately capturing the dynamic details of the flow rate, thus improving the accuracy of instantaneous flow rate and the total cumulative accuracy.

[0087] If the value is below the safety threshold, the measurement frequency is adjusted from the second frequency to the first frequency. If the second frequency is higher than the first frequency, the measurement frequency is reduced, the cycle of the second step is extended, and the device enters a low-power sleep state until the next measurement or when it is woken up.

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

[0089] It should be noted that, in this embodiment, the dynamic adjustment strategy for the measurement frequency also includes accepting the adjustment request issued by the error surface compensation model. Specifically, when in steady-state low-frequency measurement mode, the error compensation itself can act as a "listener" that can record the current index position and interpolation distance during each interpolation calculation.

[0090] If a jump is detected between two consecutive LUT mesh nodes indexed by compensation calculations (e.g., a sudden jump from the (20℃, 0.1m / s) node to the (20℃, 0.5m / s) node), it means that the flow velocity may be changing drastically, 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. After receiving this signal, the measurement frequency controller can immediately or gradually increase the frequency to verify and respond to the change. This provides a novel criterion for measurement frequency adjustment based on software algorithms, making it not only based on simple hardware signals (such as the first wave ratio) or the rate of change of the original physical quantity (dV / dt), but also based on higher-level application logic (compensation algorithm state), making it more intelligent and forward-looking, and further optimizing the balance between "accuracy and power consumption".

[0091] It is also worth mentioning that in this embodiment, after receiving the ultrasonic signal and calculating the first wave ratio, the reliability of the first wave ratio is also judged. In practical applications, changes in water quality (such as bubbles and impurities), scaling on the inner wall of the pipe, contamination on the surface of the transducer, or changes in water temperature can all cause the ultrasonic signal to attenuate, reduce the amplitude of the first wave, and may even cause the subsequent reflected wave or noise wave to become the maximum wave, thereby causing the ToF capture error and generating a huge measurement error. Therefore, it is necessary to judge the reliability of the first wave ratio.

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

[0093] The first wave ratio is the ratio of the amplitude of the first wave to the amplitude of a subsequent reference wave. A high first wave ratio usually means a strong signal, less interference, a clean waveform, and a 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 feature point of the first wave is directly used as the calculation benchmark for ToF, resulting in the highest accuracy. If the first-wave ratio is lower than the reliability threshold, the signal quality is considered poor, indicating interference. In this case, the system will not simply use the first wave but will activate a backup algorithm, for example:

[0095] The similarity between the transmitted and received signals is calculated using a cross-correlation algorithm, and the Time-of-Flight (ToF) is determined based on the peak position. This method has strong anti-interference capabilities, but requires a large amount of computation.

[0096] A comprehensive judgment can be made by combining the location information of the maximum wave and the first wave, or digital filtering can be used to purify the signal.

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

[0098] The specific advantages are as follows:

[0099] Extremely high measurement accuracy under all working conditions:

[0100] Multidimensional error compensation: In addition to basic sound velocity and water temperature compensation, an advanced three-dimensional error surface compensation model indexed by water temperature and flow velocity is introduced. This can accurately correct nonlinear errors caused by complex factors such as transducer temperature drift, fluid viscosity changes, and meter body deformation, improving the accuracy of the water meter to the highest level (e.g., ±1%) across the entire range and temperature range.

[0101] Exceptional low-power performance and energy efficiency optimization:

[0102] Dynamic excitation voltage optimization: Instead of using a fixed high voltage, it dynamically finds and maintains a minimum effective excitation voltage while ensuring signal reliability, which directly and significantly reduces the power consumption of the ultrasonic transducer, the main energy-consuming unit, from the source.

[0103] Intelligent frequency adjustment: The sampling frequency is dynamically adjusted based on the rate of change of flow velocity and water temperature. It enters a low-frequency sleep mode to save power during steady-state flow and quickly switches to a high-frequency mode to maintain accuracy during dynamic flow. This achieves "deep energy saving in static conditions and precise capture in dynamic conditions."

[0104] Dual energy-saving synergy: The excitation voltage regulation and measurement frequency regulation are linked together (such as temporary frequency increase during voltage regulation), forming a synergistic energy-saving effect and 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 "judge" of signal quality can effectively deal with complex on-site 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, it does not directly use the potentially erroneous first wave, but instead activates backup algorithms such as cross-correlation for calculation, ensuring that the metering function can still be maintained under adverse conditions and that no huge errors will occur.

[0108] Hysteresis and asymptotic adjustment: The voltage regulation adopts an asymptotic step size and hysteresis range, which prevents the system from oscillating and switching frequently near the critical point, and enhances 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 velocity V = 0.8 m / s, R = 0.9 (signal strong), the signal is too strong, so the voltage is gradually reduced. The speed of sound c = 1482.8 m / s. By referring to the table and interpolating, δ = +0.2%, and the frequency is maintained at 8 Hz.

[0125] t=1.2;

[0126] Flow velocity V = 1.5 m / s, R = 0.92, excitation voltage reduced to 10V, sound velocity c = 1482.8 m / s, from table: δ = -0.5%, maintained at 8Hz;

[0127] At t=10, the water temperature begins 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, it was found that the temperature index jumped from 20℃ to 25℃. A "temperature change warning" was sent in reverse. It was confirmed that dT / dt increased. The high-frequency mode was maintained at 8Hz.

[0129] t=20;

[0130] T=30℃, V=1.5 m / s, R=0.87. Based on T=30℃, consult the voltmeter and fine-tune the excitation voltage to 9.5V. The speed of sound c=1509.5 m / s. From the table, δ=-1.0%, maintain 8Hz.

[0131] At t=40, a new steady state is reached;

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

[0133] At t=50, the flow is steady.

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

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

[0136] Frequency adaptation serves as a pioneering technique, first detecting a sharp change in flow velocity (dV / dt) through hardware and immediately increasing the measurement frequency from 1Hz to 8Hz. This provides a high-precision instantaneous data source for all subsequent techniques, ensuring the entire system keeps pace with changes.

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

[0138] As the flow velocity increases, the signal transmission conditions improve, and the initial wave ratio R increases.

[0139] The first wave ratio adaptive feeds back a high-quality R value to the excitation voltage for adaptive operation.

[0140] Based on this, the excitation voltage adaptively decides to reduce the excitation voltage from 12V to 10V, achieving energy saving while ensuring signal quality.

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

[0142] Sound speed compensation always provides an accurate sound speed value c(T), completing the basic compensation.

[0143] Error compensation is the core of accuracy. It utilizes precise (T,V) data obtained from high-frequency measurements to perform real-time table lookup and interpolation compensation. For example, at the point (35℃, 1.5m / s), it compensates for an error of -1.3%.

[0144] Key linkage: Error compensation detects changes in the water temperature index during calculation and sends a warning to the frequency adaptive system, reinforcing the decision to maintain high-frequency measurements. This demonstrates the intelligent guidance from the algorithm layer to the system control layer.

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

[0146] Once the system enters a new stable state, frequency adaptation comes into play again, reducing the measurement frequency from a high-performance 8Hz to a balanced 2Hz for power consumption and accuracy, demonstrating the system's energy-saving awareness.

[0147] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. An adaptive metering method for an ultrasonic water meter, characterized by: The method comprises the following steps: obtaining 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 a 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 an initial flow value, wherein the first wave ratio refers to the ratio of the amplitude of the first wave to the amplitude of a subsequent reference wave, and the excitation voltage adaptive adjustment strategy comprises calculating the first wave ratio based on the received ultrasonic receiving signal, and 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; performing secondary compensation using the 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] starting from the initial value of the excitation voltage; 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, wherein: 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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