Ultrasonic guided wave liquid level and wave height measuring method based on SH0 mode

Abstract

The invention discloses an ultrasonic guided wave liquid level and wave height measurement method based on an SH0 mode, which is realized through a measurement system, and the measurement system is composed of a waveguide rod, an ultrasonic transducer arranged on the waveguide rod, a reflection attenuation block arranged at the top end of the waveguide rod, and a circuit module electrically connected with the ultrasonic transducer. According to the ultrasonic guided wave liquid level and wave height measurement method based on the SH0 mode, through selection of the SH0 mode and optimized system design, energy leakage is effectively reduced, the wave speed of ultrasonic guided waves is better stabilized, the anti-interference capacity of the guided waves is improved, and therefore high-precision and high-stability liquid level and wave height measurement is achieved.

Description

Technical Field

[0001] This application relates to the field of liquid level and wave height measurement, specifically to an ultrasonic guided wave liquid level and wave height measurement method based on the SHO mode. Background Technology

[0002] Currently, there are various technologies for measuring liquid level and wave height, but all of them have certain limitations: (1) Float type / pressure type: The mechanical structure is complex and easily affected by liquid level fluctuations. Pressure type measurement is significantly affected by atmospheric pressure fluctuations and liquid density.

[0003] (2) Radar / laser type: non-contact measurement, which is very sensitive to environments such as water surface foam, steam, and wave splash, and is prone to measurement errors.

[0004] (3) Traditional ultrasonic echo method: This is the most common non-contact ultrasonic method. Its principle is that the probe emits ultrasonic waves towards the liquid surface and receives the echoes, measuring the distance by calculating the transit time. However, this method has inherent drawbacks: (3-1) Susceptible to environmental interference: Temperature gradients, humidity changes, foam, and steam can severely alter the propagation speed of ultrasound in the air or attenuate the signal, leading to decreased accuracy or even inaccuracy.

[0005] (3-2) High installation requirements: precise alignment is required, and the acoustic cone angle may cause interference echoes from non-liquid objects.

[0006] (3-3) Limited dynamic measurement performance: In dynamic scenarios such as waves, the echo signal is unstable and it is difficult to accurately capture the instantaneous position of the wave surface.

[0007] In recent years, ultrasonic guided wave technology has attracted attention due to its concentrated energy and long propagation distance. However, existing guided wave liquid level measurement methods mostly employ longitudinal modes (such as L(0,1), L(0,2)) or bending modes. Through in-depth research, the applicant has identified the following technical bottlenecks in existing guided wave measurement technology: (i) Energy leakage problem: Longitudinal modal guided waves radiate significant energy into the liquid at the liquid surface, resulting in weak reflected signals and low signal-to-noise ratio. Experiments show that the energy loss of the L(0,2) mode at the liquid surface can reach more than 30%, which seriously affects the reliability of echo detection.

[0008] (ii) Wave velocity instability: The wave velocity of the longitudinal mode is significantly affected by the liquid loading effect. When the liquid density or viscosity changes, or when foam is present on the liquid surface, the wave velocity will drift, introducing systematic measurement errors. Measured data show that the wave velocity of the L(0,2) mode can vary by 5%-8% in water and air.

[0009] (iii) Poor anti-interference ability: Traditional longitudinal mode is sensitive to changes in liquid properties. Contaminants such as foam and oil on the liquid surface will significantly change the reflection characteristics, leading to measurement failure. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this application provides an ultrasonic guided wave liquid level and wave height measurement method based on the SH0 mode. By selecting the SH0 mode and optimizing the system design, energy leakage is effectively reduced, the wave velocity of the ultrasonic guided wave is better stabilized, and the anti-interference capability of the guided wave is improved, thereby achieving high-precision and high-stability liquid level and wave height measurement.

[0011] An ultrasonic guided wave liquid level and wave height measurement method based on SHO mode is implemented by a measurement system, which consists of a waveguide rod, an ultrasonic transducer mounted on the waveguide rod, a reflection attenuation block mounted at the top of the waveguide rod, and a circuit module electrically connected to the ultrasonic transducer.

[0012] Furthermore, the circuit module comprises a signal generation and acquisition unit electrically connected to the ultrasonic transducer, a signal processing unit electrically connected to the signal generation and acquisition unit, and a communication interface electrically connected to the signal processing unit.

[0013] Preferably, the waveguide rod has a diameter of 3-20 mm, a surface finish Ra≤0.1 mm, and is vertically inserted into the liquid.

[0014] Preferably, the ultrasonic transducer is bonded to the outside of the waveguide rod; the ultrasonic transducer is a ring ultrasonic transducer or a plate ultrasonic transducer. The annular ultrasonic transducer is a polarized piezoelectric ceramic ring, which is polarized in the radial direction. Silver electrodes are provided on the inner and outer surfaces of the piezoelectric ceramic ring, and the piezoelectric ceramic ring is bonded to the waveguide rod by conductive adhesive. Alternatively, the plate-type ultrasonic transducer comprises several in-plane polarized piezoelectric ceramic sheets distributed circumferentially along the surface of the waveguide rod. The electrodes of each piezoelectric ceramic sheet are connected in parallel, and the piezoelectric ceramic sheets are bonded to the waveguide rod with conductive adhesive; the spacing between any two adjacent piezoelectric ceramic sheets... ;in, The wavelength of the ultrasonic guided wave transmitted in the waveguide rod is given.

[0015] Preferably, in scenarios requiring short distance, fast response, low power consumption, and low cost, the circuit module adopts a pulse excitation mode. Specifically, it consists of an MCU as a signal processing unit, a communication interface electrically connected to the MCU, a pulse generator whose input is electrically connected to the MCU and whose output is connected to the ultrasonic transducer after passing through a high-voltage amplifier, a low-noise amplifier whose input is electrically connected to the ultrasonic transducer and whose output is connected to the input of a bandpass filter, and a high-speed comparator whose input is electrically connected to the output of the bandpass filter and whose output is connected to the TDC; wherein, the TDC is bidirectionally electrically connected to the MCU.

[0016] As a preferred embodiment, the specific measurement process for the transit time of the ultrasonic pulse in the pulse excitation mode is as follows: (1-1) The MCU controls the pulse generator to send pulse signals; The pulse signal is a single pulse signal or a multi-pulse signal; (1-2) The pulse signal is amplified by a high-voltage amplifier; (1-3) The amplified pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer and coupled into the surface of the waveguide rod to propagate forward; The pulse width T of the ultrasonic guided wave pulse is determined according to the resonant frequency f0 of the ultrasonic transducer, and the calculation formula is T = 1 / f0; (1-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod. (1-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer and then amplified by a low-noise amplifier; (1-6) The amplified received signal is filtered by a bandpass filter and then enters a high-speed comparator; (1-7) The high-speed comparator generates a receive pulse signal for the timing end signal within a set threshold range; (1-8) By measuring the received pulse signal through TDC, the transit time of the ultrasonic pulse is finally accurately measured; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer to when the received signal returns to the ultrasonic transducer.

[0017] In scenarios requiring long distances, high precision, and strong anti-interference capabilities, the circuit module adopts a Hanning window modulated sinusoidal pulse mode. Specifically, it consists of an MCU and an FPGA as signal processing units, a communication interface electrically connected to the MCU, a DDS waveform generator whose input is electrically connected to the FPGA and whose output is electrically connected to the ultrasonic transducer after passing through a high-voltage amplifier, and a low-noise amplifier whose input is electrically connected to the ultrasonic transducer and whose output is electrically connected to the FPGA after passing through a bandpass filter and a high-speed ADC in sequence; wherein, the MCU and FPGA are bidirectionally electrically connected.

[0018] As another preferred embodiment, the specific measurement process of the transit time of the ultrasonic pulse in the Hanning window modulated sinusoidal pulse mode is as follows: (2-1) The FPGA controls the DDS waveform generator to emit a sinusoidal pulse signal; (2-2) The sinusoidal pulse signal is amplified by a high-voltage amplifier; (2-3) The amplified sinusoidal pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer and coupled into the surface of the waveguide rod to propagate forward; The dominant frequency f of the sinusoidal pulse signal S The resonant frequency f0 of the ultrasonic transducer is the same; (2-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod. (2-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer and then amplified by a low-noise amplifier; (2-6) The amplified received signal is filtered by a bandpass filter and then enters the high-speed ADC, where it is converted into a digital signal. The sampling frequency of the high-speed ADC is 2-20 Msps; (2-7) The digital signal enters the FPGA through the high-speed ADC, and the transit time of the ultrasonic pulse is obtained in the FPGA by calculating the peak value of the cross-correlation function between the ultrasonic pulse and the received signal; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer to when the received signal returns to the ultrasonic transducer.

[0019] Preferably, the waveguide rod is also provided with a temperature sensor electrically connected to the MCU; in steps (1-8), the MCU will provide the TDC with real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod according to the feedback signal of the temperature sensor; in steps (2-7), the MCU will provide the FPGA with real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod according to the feedback signal of the temperature sensor. The high-voltage amplifier circuit amplifies the pulse signal or sinusoidal pulse signal to a peak-to-peak value of 40-150V; the low-noise amplifier amplifies the gain of the received signal to 50-500 times; and the passband range of the bandpass filter is 200-850kHz.

[0020] Preferably, the formula for calculating the liquid level using the transit time is: ; in, This represents the actual liquid level. The zero-point liquid level is the value measured at the factory or during initial design. To determine the initial transit time, S represents the actual transit time, and S represents the wave velocity of the ultrasonic guided wave. The formula for calculating wave height is: ; in, Wave height is t, and time is t. The highest actual liquid level within a unit of time t. It represents the lowest actual liquid level within a unit of time t.

[0021] Compared with the prior art, the embodiments of this application have the following beneficial effects: By selecting the SHO mode and optimizing the system design, this invention effectively reduces energy leakage, better stabilizes the wave velocity of the ultrasonic guided wave, and improves the anti-interference capability of the guided wave, thereby achieving high-precision and high-stability liquid level and wave height measurement.

[0022] Some of the additional features of this application can be further described in the following description. By examining the following description and corresponding drawings, or by understanding the operation and training process of the embodiments, those skilled in the art can clearly recognize some of the additional technical effects proposed in this application. The features disclosed in this application can be implemented and obtained through the practice of various construction methods, training processes, and combinations of different modules, strategies, and structures in specific embodiments. Attached Figure Description

[0023] The accompanying drawings, which are provided to further illustrate this application and constitute a part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute a limitation thereof. In the drawings, the same reference numerals denote the same components. Figure 1 This is a schematic diagram of the measurement system of the present invention.

[0024] Figure 2 (a) is a schematic diagram of the setup of the annular ultrasonic transducer in the measurement system of the present invention.

[0025] Figure 2 (b) is a schematic diagram of the installation of the plate ultrasonic transducer in the measurement system of the present invention.

[0026] Figure 3 This is the first implementation of the signal generation and acquisition unit of the present invention.

[0027] Figure 4 This is a second implementation of the signal generation and acquisition unit of the present invention.

[0028] Explanation of reference numerals in the attached figures: 100 Waveguide rod; 200 Ultrasonic transducer; 200-1 Ring ultrasonic transducer; 200-2 Plate ultrasonic transducer; 300 Reflection attenuation block; 400 Signal generation and acquisition unit; 500 Signal processing unit; 600 Communication interface. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0030] It should be noted that if the terms "first," "second," etc., are used in the specification, claims, and accompanying drawings of this application, they are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] In this application, when terms such as "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" are used, they indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are mainly for better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0032] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0033] Furthermore, in this application, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] Example 1 like Figure 1 As shown, an ultrasonic guided wave liquid level and wave height measurement method based on SHO mode is implemented through a measurement system. The measurement system consists of a waveguide rod 100, an ultrasonic transducer 200 mounted on the waveguide rod 100, a reflection attenuation block 300 mounted at the top of the waveguide rod 100, and a circuit module electrically connected to the ultrasonic transducer 200.

[0036] The reflection attenuation block is made of rubber or nylon. It is inserted into the proximal end of the waveguide rod connected to the annular ultrasonic transducer by interference fit to attenuate the proximal reflection and connect the waveguide rod to the housing of the level gauge or wave height meter.

[0037] The circuit module comprises a signal generation and acquisition unit 400 electrically connected to the ultrasonic transducer 200, a signal processing unit 500 electrically connected to the signal generation and acquisition unit 400, and a communication interface 600 electrically connected to the signal processing unit 500.

[0038] The waveguide rod 100 has a diameter of 3 mm, a surface finish Ra≤0.1 mm, and is vertically inserted into the liquid.

[0039] The waveguide rod is a solid rod made of uniform materials such as stainless steel, aluminum, fiberglass, carbon fiber, and ceramic.

[0040] like Figure 2 As shown in Figure a, the ultrasonic transducer 200 is bonded and coupled to the outside of the waveguide rod 100; the ultrasonic transducer 200 is a ring ultrasonic transducer 200-1. This embodiment can generate uniform circumferential shear force through an optimized annular ultrasonic transducer, ensuring the excitation of pure SHO modes and suppressing unnecessary other modes.

[0041] Alternatively, the ultrasonic transducer can also be simply implemented as a "magnetostrictive ultrasonic transducer," which operates on the same principle as a ring ultrasonic transducer.

[0042] The annular ultrasonic transducer 200-1 is a polarized piezoelectric ceramic ring, which is polarized in the radial direction. Silver electrodes are provided on the inner and outer surfaces of the piezoelectric ceramic ring, and the piezoelectric ceramic ring is bonded to the waveguide rod 100 by conductive adhesive.

[0043] like Figure 3 As shown, in scenarios requiring short distance, fast response, low power consumption, and low cost, the circuit module adopts a pulse excitation mode. Specifically, it consists of an MCU as a signal processing unit 500, a communication interface 600 electrically connected to the MCU, a pulse generator whose input is electrically connected to the MCU and whose output is electrically connected to the ultrasonic transducer 200 after passing through a high-voltage amplifier, a low-noise amplifier whose input is electrically connected to the ultrasonic transducer 200 and whose output is electrically connected to the input of a bandpass filter, and a high-speed comparator whose input is electrically connected to the output of the bandpass filter and whose output is electrically connected to a TDC; wherein, the TDC is bidirectionally electrically connected to the MCU.

[0044] The specific measurement process for the transit time of the ultrasonic pulse in the pulse excitation mode is as follows: (1-1) The MCU controls the pulse generator to send pulse signals; The pulse signal is a single pulse signal or a multi-pulse signal; (1-2) The pulse signal is amplified by a high-voltage amplifier; (1-3) The amplified pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer 200 and coupled into the surface of the waveguide rod 100 to propagate forward; The pulse width T of the ultrasonic guided wave pulse is determined according to the resonant frequency f0 of the ultrasonic transducer 200, and the calculation formula is T = 1 / f0. (1-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod 100. (1-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer 200 and amplified by the low-noise amplifier; (1-6) The amplified received signal is filtered by a bandpass filter and then enters a high-speed comparator; (1-7) The high-speed comparator generates a receive pulse signal for the timing end signal within a set threshold range; (1-8) By measuring the received pulse signal through TDC, the transit time of the ultrasonic pulse is finally accurately measured; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer 200 to when the received signal returns to the ultrasonic transducer 200.

[0045] The waveguide rod 100 is also equipped with a temperature sensor that is electrically connected to the MCU; in steps (1-8), the MCU will provide the TDC with real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod 100 according to the feedback signal of the temperature sensor. c_g = c_g0[1 + α(T - T0)] Where c_g is the actual wave velocity, c_g0 is the calibrated wave velocity, α is the temperature coefficient, T is the current temperature, and T0 is the reference temperature.

[0046] The high-voltage amplifier circuit amplifies the pulse signal or sinusoidal pulse signal to a peak-to-peak value of 40V; the low-noise amplifier amplifies the gain of the received signal by 50 times; and the passband range of the bandpass filter is 200kHz.

[0047] The formula for calculating the liquid level based on the transit time is: ; in, This represents the actual liquid level. The zero-point liquid level is the value measured at the factory or during initial design. To determine the initial transit time, S represents the actual transit time, and S represents the wave velocity of the ultrasonic guided wave. The formula for calculating wave height is: ; in, Wave height is t, and time is t. The highest actual liquid level within a unit of time t. It represents the lowest actual liquid level within a unit of time t.

[0048] This embodiment selects the SHO mode as the measurement carrier, utilizing its characteristic that the particle vibration direction is parallel to the tangential direction of the waveguide rod circumference to achieve weak coupling with the liquid, fundamentally solving the energy leakage problem. Through the total internal reflection characteristic and high-precision transit time measurement of the SHO mode, sub-millimeter-level measurement accuracy is achieved, more than 10 times higher than traditional methods, improving measurement accuracy by an order of magnitude. Since the SHO mode can achieve total internal reflection at the liquid surface, its reflection coefficient is close to 1, while the reflection coefficient of the traditional longitudinal mode is only 0.6-0.7, thus essentially completely solving the energy leakage problem. The wave velocity of the SHO mode is completely unaffected by the liquid properties, fundamentally eliminating measurement errors introduced by changes in liquid density and viscosity; therefore, this embodiment has no liquid load effect. This embodiment is naturally immune to interference factors such as liquid surface foam, steam, and temperature gradients, making it suitable for various complex industrial environments. Because the complete signal processing cycle of this embodiment is less than 1 ms, it can accurately capture dynamic wave changes with frequencies up to 50 Hz, thus exhibiting excellent dynamic response characteristics.

[0049] Example 2 The only difference between this embodiment and Embodiment 1 is that the diameter of the waveguide rod 100 is 20mm.

[0050] The high-voltage amplifier circuit amplifies the pulse signal or sinusoidal pulse signal to a peak-to-peak value of 150V; the low-noise amplifier amplifies the gain of the received signal by 500 times; and the passband range of the bandpass filter is 850kHz.

[0051] Example 3 The only difference between this embodiment and Embodiment 1 is that the diameter of the waveguide rod 100 is 10mm.

[0052] The high-voltage amplifier circuit amplifies the pulse signal or sinusoidal pulse signal to a peak-to-peak value of 100V; the low-noise amplifier amplifies the gain of the received signal by 300 times; and the passband range of the bandpass filter is 500kHz.

[0053] Example 4 like Figure 2 As shown in Figure b, the ultrasonic transducer 200 is bonded and coupled to the outside of the waveguide rod 100; the ultrasonic transducer 200 is a plate-type ultrasonic transducer 200-2. The only difference between this embodiment and Embodiment 1 is that the plate-type ultrasonic transducer 200-2 consists of several in-plane polarized piezoelectric ceramic sheets distributed circumferentially along the surface of the waveguide rod 100. The electrodes of each piezoelectric ceramic sheet are connected in parallel, and the piezoelectric ceramic sheets are bonded to the waveguide rod 100 with conductive adhesive; the spacing between any two adjacent piezoelectric ceramic sheets... ;in, The wavelength of the ultrasonic guided wave transmitted in the waveguide rod 100.

[0054] Example 5 like Figure 4 As shown, the difference between this embodiment and Embodiment 1 is that, in scenarios requiring long distances, high precision, and strong anti-interference capabilities, the circuit module adopts a Hanning window modulated sinusoidal pulse mode. Specifically, it consists of an MCU and an FPGA as signal processing units 500, a communication interface 600 electrically connected to the MCU, a DDS waveform generator whose input is electrically connected to the FPGA and whose output is electrically connected to the ultrasonic transducer 200 after passing through a high-voltage amplifier, and a low-noise amplifier whose input is electrically connected to the ultrasonic transducer 200 and whose output is electrically connected to the FPGA after passing through a bandpass filter and a high-speed ADC in sequence; wherein, the MCU and FPGA are bidirectionally electrically connected.

[0055] The specific measurement process of the transit time of the ultrasonic pulse in the Hanning window modulated sinusoidal pulse mode is as follows: (2-1) The FPGA controls the DDS waveform generator to emit a sinusoidal pulse signal; (2-2) The sinusoidal pulse signal is amplified by a high-voltage amplifier; (2-3) The amplified sinusoidal pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer 200 and coupled into the surface of the waveguide rod 100 to propagate forward; The dominant frequency f of the sinusoidal pulse signal S The resonant frequency f0 of the ultrasonic transducer 200 is the same. (2-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod 100. (2-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer 200 and then amplified by the low-noise amplifier; (2-6) The amplified received signal is filtered by a bandpass filter and then enters the high-speed ADC, where it is converted into a digital signal. The sampling frequency of the high-speed ADC is 2 Msps; (2-7) The digital signal enters the FPGA through the high-speed ADC, and the transit time of the ultrasonic pulse is obtained in the FPGA by calculating the peak value of the cross-correlation function between the ultrasonic pulse and the received signal; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer 200 to when the received signal returns to the ultrasonic transducer 200.

[0056] The waveguide rod 100 is also equipped with a temperature sensor that is electrically connected to the MCU; in step (2-7), the MCU will provide the FPGA with real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod 100 based on the feedback signal of the temperature sensor.

[0057] Example 6 The only difference between this embodiment and Embodiment 5 is that the sampling frequency of the high-speed ADC is 20Msps.

[0058] Example 7 The only difference between this embodiment and embodiment 5 is that the sampling frequency of the high-speed ADC is 10Msps.

[0059] Comparative Example 1 The performance indicators of the measurement method of this application, the traditional longitudinal modal measurement method, and the traditional ultrasonic volume wave measurement method are compared and listed in Table 1 below: Table 1 As shown in Table 1, the measurement method of this application is superior to the traditional longitudinal modal measurement method and the traditional ultrasonic body wave measurement method in terms of accuracy, stability, and stability.

[0060] It should be noted that all features disclosed in this specification, or all steps in all methods or processes disclosed, may be combined in any way, except for mutually exclusive features and / or steps.

[0061] Furthermore, the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents.

Claims

1. A method for measuring ultrasonic guided wave liquid level and wave height based on SHO mode, characterized in that, This is achieved through a measurement system consisting of a waveguide rod (100), an ultrasonic transducer (200) mounted on the waveguide rod (100), a reflection attenuation block (300) mounted at the top of the waveguide rod (100), and a circuit module electrically connected to the ultrasonic transducer (200).

2. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 1, characterized in that, The circuit module comprises a signal generation and acquisition unit (400) electrically connected to the ultrasonic transducer (200), a signal processing unit (500) electrically connected to the signal generation and acquisition unit (400), and a communication interface (600) electrically connected to the signal processing unit (500).

3. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 2, characterized in that, The waveguide rod (100) has a diameter of 3-20 mm and a surface finish Ra≤0.1 mm, and the waveguide rod (100) is vertically inserted into the liquid.

4. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 3, characterized in that, The ultrasonic transducer (200) is bonded to the outside of the waveguide rod (100); the ultrasonic transducer (200) is a ring ultrasonic transducer (200-1) or a plate ultrasonic transducer (200-2). The annular ultrasonic transducer (200-1) is a polarized piezoelectric ceramic ring, which is polarized in the radial direction. Silver electrodes are provided on the inner and outer surfaces of the piezoelectric ceramic ring, and the piezoelectric ceramic ring is bonded to the waveguide rod (100) by conductive adhesive. Alternatively, the plate-type ultrasonic transducer (200-2) comprises several in-plane polarized piezoelectric ceramic sheets distributed circumferentially along the surface of the waveguide rod (100), with the electrodes of each piezoelectric ceramic sheet connected in parallel, and the piezoelectric ceramic sheets bonded to the waveguide rod (100) by conductive adhesive; the spacing between any two adjacent piezoelectric ceramic sheets... ;in, The wavelength of the ultrasonic guided wave transmitted in the waveguide rod (100).

5. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 4, characterized in that, In scenarios requiring short distance, fast response, low power consumption, and low cost, the circuit module adopts a pulse excitation mode. Specifically, it consists of an MCU as a signal processing unit (500), a communication interface (600) electrically connected to the MCU, a pulse generator whose input is electrically connected to the MCU and whose output is electrically connected to the ultrasonic transducer (200) after passing through a high-voltage amplifier, a low-noise amplifier whose input is electrically connected to the ultrasonic transducer (200) and whose output is electrically connected to the input of a bandpass filter, and a high-speed comparator whose input is electrically connected to the output of the bandpass filter and whose output is electrically connected to the TDC; wherein, the TDC is bidirectionally electrically connected to the MCU.

6. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 5, characterized in that, The specific measurement process for the transit time of the ultrasonic pulse in the pulse excitation mode is as follows: (1-1) The MCU controls the pulse generator to send pulse signals; The pulse signal is a single pulse signal or a multi-pulse signal; (1-2) The pulse signal is amplified by a high-voltage amplifier; (1-3) The amplified pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer (200) and coupled into the surface of the waveguide rod (100) to propagate forward; The pulse width T of the ultrasonic guided wave pulse is determined according to the resonant frequency f0 of the ultrasonic transducer (200), and the calculation formula is T = 1 / f0. (1-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod (100); (1-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer (200) and amplified by the low-noise amplifier; (1-6) The amplified received signal is filtered by a bandpass filter and then enters a high-speed comparator; (1-7) The high-speed comparator generates a receive pulse signal for the timing end signal within a set threshold range; (1-8) By measuring the received pulse signal through TDC, the transit time of the ultrasonic pulse is finally accurately measured; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer (200) to when the received signal returns to the ultrasonic transducer (200).

7. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 4, characterized in that, In scenarios requiring long distances, high precision, and strong anti-interference capabilities, the circuit module adopts a Hanning window modulation sinusoidal pulse mode. Specifically, it consists of an MCU and an FPGA as signal processing units (500), a communication interface (600) electrically connected to the MCU, a DDS waveform generator whose input is electrically connected to the FPGA and whose output is electrically connected to the ultrasonic transducer (200) after passing through a high-voltage amplifier, and a low-noise amplifier whose input is electrically connected to the ultrasonic transducer (200) and whose output is electrically connected to the FPGA after passing through a bandpass filter and a high-speed ADC in sequence; wherein, the MCU and the FPGA are bidirectionally electrically connected.

8. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 7, characterized in that, The specific measurement process of the transit time of the ultrasonic pulse in the Hanning window modulated sinusoidal pulse mode is as follows: (2-1) The FPGA controls the DDS waveform generator to emit a sinusoidal pulse signal; (2-2) The sinusoidal pulse signal is amplified by a high-voltage amplifier; (2-3) The amplified sinusoidal pulse signal is converted into an ultrasonic guided wave pulse by the ultrasonic transducer (200) and coupled into the surface of the waveguide rod (100) to propagate forward; The dominant frequency f of the sinusoidal pulse signal S The resonant frequency f0 of the ultrasonic transducer (200) is the same; (2-4) When some ultrasonic guided wave pulses come into contact with the liquid surface, they will be reflected, and the reflected ultrasonic guided wave pulses will propagate in the opposite direction along the waveguide rod (100); (2-5) The reverse-propagating ultrasonic guided wave pulse is converted into an electrical signal by the ultrasonic transducer (200) and amplified by the low-noise amplifier; (2-6) The amplified received signal is filtered by a bandpass filter and then enters the high-speed ADC, where it is converted into a digital signal. The sampling frequency of the high-speed ADC is 2-20 Msps; (2-7) The digital signal enters the FPGA through the high-speed ADC, and the transit time of the ultrasonic pulse is obtained in the FPGA by calculating the peak value of the cross-correlation function between the ultrasonic pulse and the received signal; The transit time specifically refers to the time from when the ultrasonic pulse is emitted by the ultrasonic transducer (200) to when the received signal returns to the ultrasonic transducer (200).

9. A method for measuring ultrasonic guided wave liquid level and wave height based on SHO mode according to any one of claims 5-8, characterized in that, The waveguide rod (100) is also equipped with a temperature sensor electrically connected to the MCU; in steps (1-8), the MCU will provide real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod (100) to the TDC based on the feedback signal of the temperature sensor; in steps (2-7), the MCU will provide real-time temperature compensation for the ultrasonic guided wave velocity in the waveguide rod (100) to the FPGA based on the feedback signal of the temperature sensor. The high-voltage amplifier circuit amplifies the pulse signal or sinusoidal pulse signal to a peak-to-peak value of 40-150V; the low-noise amplifier amplifies the gain of the received signal to 50-500 times; and the passband range of the bandpass filter is 200-850kHz.

10. The ultrasonic guided wave liquid level and wave height measurement method based on SHO mode according to claim 9, characterized in that, The formula for calculating the liquid level based on the transit time is: ； in, This represents the actual liquid level. The zero-point liquid level is the value measured at the factory or during initial design. To determine the initial transit time, S represents the actual transit time, and S represents the wave velocity of the ultrasonic guided wave. The formula for calculating wave height is: ； in, Wave height is t, and time is t. The highest actual liquid level within a unit of time t. It represents the lowest actual liquid level within a unit of time t.

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