Ultrasonic back scattering and reflection combined sediment concentration measuring system and method

Abstract

The invention discloses an ultrasonic back scattering and reflection combined sediment concentration measuring system and method. The system comprises an ultrasonic underwater measurement device, a circuit box body and a remote host end. The ultrasonic underwater measurement device comprises a fixed rod, an ultrasonic transducer, a reflecting wall and a distance regulation track between the fixed rod and the reflecting wall; a transducer driving module, a signal receiving and conditioning module, a data acquisition module, an FPGA (Field Programmable Gate Array) control module, a power supply module and an SDI-12 communication module are arranged in the circuit box body; the remote host end is a USB conversion port and an upper computer; the transducer driving module and the signal receiving and conditioning module in the box body are connected with the transducer through a waterproof cable; the FPGA control module is connected with other modules in the circuit box body; and the USB conversion port is connected with the SDI-12 communication module in the box body through a cable. The device has the advantages of being convenient to operate and high in measurement precision, the silt concentration range capable of being measured in real time ranges from 0 kg / m < 3 > to 120 kg / m < 3 >, and the device can be effectively used for monitoring the river silt concentration.

Description

Technical Field

[0001] The invention belongs to the technical field of sediment measurement, and in particular to a sediment concentration measurement system and method combining ultrasonic backscattering and reflection. Background Art

[0002] The water quality of rivers is the focus of water resource protection. The Yangtze River and the Yellow River are the two most important rivers in China. The monitoring of the sediment content of the two rivers has always been a world-class problem faced by my country's environmental science field. In order to protect the water safety of the Yangtze River and the Yellow River, my country has proposed a national key R&D plan project "Development and Demonstration of Online Automatic Monitoring Devices for Flow and Sediment in the Yangtze River and the Yellow River", striving to provide strong support for the regulation and carrying capacity of water resources in the Yangtze River and the Yellow River, the improvement of water environment quality, and the restoration of river and lake ecosystem functions.

[0003] The measurement of sediment concentration in my country can be roughly divided into traditional methods and modern methods. Among them, traditional methods (such as instantaneous samplers and on-site water sampling, etc.) have disadvantages such as high work intensity, low operational safety, and large measurement errors, and can no longer meet the current needs of water sediment monitoring. Modern methods include optical sand measurement and ultrasonic sand measurement, both of which have the advantages of high efficiency and the ability to achieve continuous data collection. Optical sand measurement measures the concentration of suspended matter by monitoring the transmission or scattering of light in the water body. This method has low accuracy in low-concentration environments and is easily interfered by impurities and other environmental factors in the water; ultrasonic sand measurement receives the echo signal reflected by the reflecting wall and uses the attenuation of the sound wave to calculate the sediment concentration. Compared with optics, this method has the advantages of strong penetration and high adaptability, but it is not a direct measurement of sediment particles and is greatly interfered by factors such as reflecting walls. Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and to provide a sediment concentration measurement system and method combining ultrasonic backscattering and reflection. The system has the characteristics of easy operation and high measurement accuracy and can be effectively used to monitor the sediment content in water bodies.

[0005] The technical solution to achieve the purpose of the present invention is: a sediment concentration measurement system combining ultrasonic backscattering and reflection, the system comprising an ultrasonic underwater measurement device, a circuit box and a remote host terminal;

[0006] The ultrasonic underwater measuring device comprises a fixing rod, an ultrasonic transducer, a reflecting wall, and a distance control track arranged between the ultrasonic transducer and the reflecting wall;

[0007] The circuit box is provided with a transducer driving module, a signal receiving and conditioning module, a data acquisition module, an FPGA control module, a power supply module and an SDI-12 communication module; the remote host end includes a USB conversion port and a host computer;

[0008] The ultrasonic transducer is connected to the transducer driving module and the signal receiving and conditioning module in the circuit box through a waterproof cable; the FPGA control module is connected to the other modules for overall control and data processing of the system; the USB conversion port is connected to the SDI-12 communication module through a cable;

[0009] The fixing rod is used to fix the ultrasonic underwater measuring device in the suspension;

[0010] The ultrasonic transducer is used to transmit ultrasonic waves to the suspended liquid and receive scattered signals;

[0011] The reflecting wall is used to reflect the ultrasonic signal to generate an echo signal;

[0012] The distance control track is used to adjust and control the distance between the ultrasonic transducer and the reflecting wall;

[0013] The transducer driving module is used to amplify the power of the discontinuous PWM pulses output by the FPGA control module to ensure that the ultrasonic transducer emits ultrasonic waves in an optimal state;

[0014] The signal receiving and conditioning module is used to process the scattered signals and echo signals received by the ultrasonic transducer, including signal amplification and filtering;

[0015] The data acquisition module is used to convert the analog signal output by the signal receiving and conditioning module into a digital signal and transmit the data to the FPGA control module;

[0016] The FPGA control module is used to generate PWM drive pulses, receive commands from the host computer, perform data preprocessing, and control the work of other modules;

[0017] The power supply module is used to convert the voltage of the external power supply into the working voltage required by other modules for power supply;

[0018] The SDI-12 communication module is used to transmit data received from the FPGA control module to a remote host terminal through the SDI-12 communication protocol, or to transmit commands from the remote host terminal to the FPGA control module;

[0019] The USB conversion port is used to convert data transmitted over a long distance using the SDI-12 communication protocol into USB protocol data and transmit it to the host computer;

[0020] The host computer is used to process the data to obtain the sediment concentration of the suspension to be tested.

[0021] Furthermore, one end of the ultrasonic transducer and the distance control track is fixed to the fixing rod, and the reflecting wall is fixed to the other end of the distance control track and is flush with the surface of the ultrasonic probe of the ultrasonic transducer.

[0022] Furthermore, the signal receiving and conditioning module includes a mV-level signal amplification circuit, a high-pass filter circuit, and a band-pass filter circuit composed of LC resonance, which are connected in sequence;

[0023] The mV-level signal amplification circuit is used to amplify the scattered signal to a preset certain range;

[0024] The high-pass filter circuit is used to filter out low-frequency noise and power frequency interference in the signal;

[0025] The bandpass filter circuit is used to filter out high and low frequency interference signals other than the modulation center frequency.

[0026] Furthermore, the bandpass filter circuit composed of LC resonance includes a dual operational amplifier LMH6612, a first inductor, a second inductor, a first electrolytic capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor; Pin 8 of the dual operational amplifier LMH6612 is connected to the positive electrode of the first electrolytic capacitor, one end of the second capacitor, and a +5V voltage, the negative electrode of the first electrolytic capacitor and the other end of the second capacitor are grounded, Pin 3 of the dual operational amplifier LMH6612 is connected to one end of the first resistor, one end of the first inductor, and one end of the fourth capacitor, the other end of the first resistor is connected to the input signal end, the other end of the first inductor and the other end of the fourth capacitor are both grounded, and the dual operational amplifier LMH66 Pin 4 of 12 is connected to one end of the third capacitor and a -5V voltage, and the other end of the third capacitor is grounded, pin 2 of the dual operational amplifier LMH6612 is connected to one end of the second resistor and one end of the third resistor, the other end of the second resistor is grounded, the other end of the third resistor is connected to pin 1 of the dual operational amplifier LMH6612 and one end of the fourth resistor, the other end of the fourth resistor is connected to pin 5 of the dual operational amplifier LMH6612, one end of the second inductor, and one end of the fifth capacitor, the other end of the second inductor and the other end of the fifth capacitor are grounded, pin 6 of the dual operational amplifier LMH6612 is connected to one end of the fifth resistor and one end of the sixth resistor, the other end of the fifth resistor is grounded, and the other end of the sixth resistor is connected to pin 7 of the dual operational amplifier LMH6612 and the signal output end.

[0027] Further, the SDI-12 communication module is a level logic conversion circuit between the UART of the FPGA and the SDI-12, including a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a three-state buffer SN74LVC1G240DBVR, a field effect transistor BSS138, a slide switch, a sixth capacitor, and a voltage regulator diode BZX84C7V5LT1G; Pin 1 of the three-state buffer SN74LVC1G240 is connected to the control end of the FPGA, Pin 2 of the three-state buffer SN74LVC1G240 is connected to the UART_TX end of the FPGA, Pin 3 of the three-state buffer SN74LVC1G240 is grounded, Pin 5 of the three-state buffer SN74LVC1G240 is connected to a +5V voltage, Pin 4 of the three-state buffer SN74LVC1G240 is connected to one end of the eighth resistor, Pin 1 of the field effect transistor BSS138 is connected, the other end of the eighth resistor is connected to the positive electrode of the voltage-regulating diode BZX84C7V5LT1G and one end of the ninth resistor, the negative electrode of the voltage-regulating diode BZX84C7V5LT1G is grounded, the other end of the ninth resistor is connected to pin 2 of the sliding switch, pin 2 of the field effect transistor BSS138 is connected to one end of the seventh resistor and the UART_RX end of the FPGA, pin 3 of the field effect transistor BSS138 is grounded, the other end of the seventh resistor is connected to +3.3V, pin 1 of the sliding switch is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to one end of the eleventh resistor, one end of the twelfth resistor, one end of the thirteenth resistor, and one end of the sixth capacitor, the other end of the eleventh resistor is connected to pin 3 of the sliding switch, the other end of the twelfth resistor and the other end of the sixth capacitor are grounded, and the other end of the thirteenth resistor is connected to the SDI-12 communication bus.

[0028] Furthermore, the FPGA control module pre-processes the data, including number system conversion and data storage.

[0029] Furthermore, the host computer obtains the sediment concentration of the suspension to be tested by a method including but not limited to a table lookup method.

[0030] Furthermore, the table lookup method is to query a data table of a scattering voltage-concentration measurement model.

[0031] Furthermore, the data table of the scattering voltage-concentration measurement model is obtained through calibration, specifically including:

[0032] The standard scattering voltage value and acoustic attenuation coefficient of suspensions of different concentrations are measured, and the upper computer fits the data to obtain the functional relationship between the scattering voltage and the concentration, and the functional relationship between the acoustic attenuation coefficient and the concentration;

[0033] The functional relationship between scattering voltage and concentration is corrected by the acoustic attenuation coefficient, and a scattering voltage-concentration measurement model is obtained.

[0034] On the other hand, a method for measuring sediment concentration by combining ultrasonic backscattering and reflection is provided, the method comprising:

[0035] Add the calibrated suspension and immerse the ultrasonic underwater measuring device in water to fix it;

[0036] After the circuits are connected, the external power supply is turned on, and the power module in the circuit box starts to supply power to the other modules;

[0037] The FPGA control module generates a discontinuous PWM square wave pulse, performs power amplification through the transducer drive module, and drives the ultrasonic transducer to emit ultrasonic waves;

[0038] The ultrasonic transducer receives the sound wave signals backscattered by the suspended particles in the suspension and the echo signals reflected by the reflecting wall, and converts these signals into electrical signals;

[0039] The signal receiving and conditioning module amplifies and filters the electrical signal;

[0040] The host computer sends a collection command, and the FPGA control module drives the data collection module to start collecting data. The obtained data is pre-processed in the FPGA control module and then transmitted to the remote host through the SDI-12 communication module;

[0041] The USB conversion port in the remote host converts the data into USB protocol and transmits it to the host computer;

[0042] Observe and save the data displayed by the host computer, obtain multiple sets of scattering voltage and echo amplitude data at the calibration concentration, obtain the standard scattering voltage value and standard echo amplitude at the calibration concentration by taking the root mean square, and calculate the acoustic attenuation coefficient using the standard echo amplitude data;

[0043] The sediment concentration in the suspension was changed, and the above steps were repeated to obtain the standard scattering voltage value and attenuation coefficient at different concentrations, and the fitting relationship between concentration-standard scattering voltage and concentration-attenuation coefficient was obtained through data fitting;

[0044] The concentration-standard scattering voltage fitting curve is corrected by the acoustic attenuation coefficient to obtain the scattering voltage-concentration measurement model, which is then stored in the host computer.

[0045] Through the above process, the unknown sediment concentration suspension is measured using but not limited to the table lookup method.

[0046] Compared with the prior art, the present invention has the following significant advantages:

[0047] (1) The present invention is designed based on the principle of combining ultrasonic backscattering and reflection. Compared with the general echo method that uses sound attenuation (reflected wall echo) to indirectly predict sediment concentration, it focuses more on directly reflecting the relationship between sediment particles and sound wave scattering characteristics, has higher sensitivity and anti-interference ability, and higher measurement accuracy.

[0048] (2) The system of the present invention has made many improvements in the circuit design of each module. In the final invention product, the low-noise power amplifier circuit effectively enhances the transmission signal strength; the fourth-order bandpass filter composed of LC resonance effectively eliminates the noise in the received signal and improves the anti-interference ability of the system; the power conversion circuit based on linear regulator and DC-DC isolation effectively reduces ripple.

[0049] (3) The present invention adopts the SDI-12 communication protocol and designs a corresponding unique UART and SDI-12 communication level logic conversion circuit, which realizes long-distance data communication of the system and can work in a resource-constrained environment, with the advantages of low power consumption and low cost.

[0050] (4) The device of the present invention can be put into the appropriate depth of the river by the length of the fixed rod through the mechanical structure design, and the directional measurement can be carried out. In addition, the underwater measuring device is easy to disassemble, which is convenient for cleaning and replacement under long-term use.

[0051] (5) The various components and chips in the present invention have been carefully screened, and the various parts complement each other, so that the present invention can achieve real-time measurement of sediment concentration in most environments. The measurable sediment concentration range is 0 to 120 kg / m3, which has a high use value.

[0052] The present invention is further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a schematic diagram of the structure of the sediment concentration measurement system combining ultrasonic backscattering and reflection in the present invention.

[0054] Figure 2 It is a hardware composition diagram of each module inside the circuit box of the present invention.

[0055] Figure 3 It is the overall block diagram of the FPGA control module in the present invention.

[0056] Figure 4 This is the LC fourth-order bandpass filter circuit diagram of the present invention.

[0057] Figure 5 It is a circuit diagram of the SDI-12 communication module of the present invention.

[0058] Figure 6 This is a curve diagram showing the relationship between the corrected suspended sediment concentration and the scattering signal voltage.

[0059] Figure 7 A simplified schematic diagram of an experiment to measure the sediment concentration of an unknown suspension in a simulated river. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, such as a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed. Instead, other steps or units that are not clearly listed or inherent to these processes, methods, products or devices may be included.

[0062] In one embodiment, in combination Figures 1 to 3 , provides a sediment concentration measurement system combining ultrasonic backscattering and reflection, the system comprising an ultrasonic underwater measurement device, a circuit box 1 and a remote host terminal;

[0063] The ultrasonic underwater measuring device comprises a fixing rod 2, an ultrasonic transducer 3, a reflecting wall 4, and a distance control track 5 arranged between the ultrasonic transducer 3 and the reflecting wall 4;

[0064] The circuit box 1 is provided with a transducer driving module, a signal receiving and conditioning module, a data acquisition module, an FPGA control module, a power module and an SDI-12 communication module; the remote host end includes a USB conversion port 6 and a host computer 7;

[0065] The ultrasonic transducer 3 is connected to the transducer driving module and the signal receiving and conditioning module in the circuit box 1 through a waterproof cable 8; the FPGA control module is connected to the other modules for overall control and data processing of the system; the USB conversion port 6 is connected to the SDI-12 communication module through a cable 9;

[0066] The fixing rod 2 is used to fix the ultrasonic underwater measuring device in the suspension;

[0067] The ultrasonic transducer 3 is used to transmit ultrasonic waves to the suspended liquid and receive scattered signals;

[0068] The reflecting wall 4 is used to reflect the ultrasonic signal to generate an echo signal;

[0069] The distance control track 5 is used to adjust and control the distance between the ultrasonic transducer 3 and the reflection wall 4;

[0070] The transducer driving module is used to amplify the power of the discontinuous PWM pulses output by the FPGA control module to ensure that the ultrasonic transducer 3 emits ultrasonic waves in an optimal state;

[0071] The signal receiving and conditioning module is used to process the scattered signal and echo signal received by the ultrasonic transducer 3, including signal amplification and filtering;

[0072] The data acquisition module is used to convert the analog signal output by the signal receiving and conditioning module into a digital signal and transmit the data to the FPGA control module;

[0073] The FPGA control module is used to generate PWM drive pulses, receive commands from the host computer, perform data preprocessing, and control the work of other modules;

[0074] The power supply module is used to convert the voltage of the external power supply into the working voltage required by other modules for power supply;

[0075] The SDI-12 communication module is used to transmit data received from the FPGA control module to a remote host terminal through the SDI-12 communication protocol, or to transmit commands from the remote host terminal to the FPGA control module;

[0076] Here, the SDI-12 communication protocol is adopted because it is suitable for hydrological and meteorological monitoring and can realize remote communication between the remote host end and the circuit box 1. In addition, it also has the advantages of low power consumption and high anti-interference.

[0077] The USB conversion port 6 is used to convert data transmitted over a long distance using the SDI-12 communication protocol into USB protocol data and transmit it to the host computer;

[0078] The host computer 7 is used to process the data to obtain the sediment concentration of the suspension to be tested.

[0079] Preferably, the ultrasonic transducer 3 is a high-performance 2Mhz self-transmitting and receiving ultrasonic probe with a sensitivity of a transmitting voltage of 24V and an echo amplitude of 800mV at a distance of 0.3m.

[0080] Preferably, the data acquisition module uses a high-precision 12-bit AD9238 chip, which has the advantages of dual-channel synchronous sampling, high sampling rate, high precision, low distortion and low power consumption, and improves the measurement accuracy of the system when measuring sediment concentration.

[0081] Preferably here, XC6SLX9-2FTG256C is selected as the core FPGA chip in the FPGA control module to meet the needs of overall control, data conversion, etc.; an SPI FLASH chip with a model of M25P16 and a capacity of 16Mbit is selected to store the startup program of the FPGA system; and an SDRAM chip with a capacity of 256Mbit16M*16bit and a model of HY57V2562GTR is selected for data storage.

[0082] Preferably, the voltage conversion in the power module is mostly designed with a linear regulator as the core circuit, and a DC-DC isolated power conversion circuit is used to effectively reduce the ripple of the output power supply.

[0083] Furthermore, in one of the embodiments, the ultrasonic transducer 3 and one end of the distance control track 5 are fixed to the fixed rod 2, and the reflective wall 4 is fixed to the other end of the distance control track 5 and is flush with the ultrasonic probe surface of the ultrasonic transducer 3.

[0084] Further, in one of the embodiments, the signal receiving and conditioning module includes a mV-level signal amplification circuit, a high-pass filter circuit, and a band-pass filter circuit composed of LC resonance, which are connected in sequence;

[0085] The mV-level signal amplification circuit is used to amplify the scattered signal to a preset certain range;

[0086] The high-pass filter circuit is used to filter out low-frequency noise and power frequency interference in the signal;

[0087] The bandpass filter circuit is used to filter out high and low frequency interference signals other than the modulation center frequency.

[0088] Preferably, in some embodiments, combined Figure 4The bandpass filter circuit composed of LC resonance includes a dual operational amplifier LMH6612, a first inductor L1, a second inductor L2, a first electrolytic capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; Pin 8 of the dual operational amplifier LMH6612 is connected to the positive electrode of the first electrolytic capacitor C1, one end of the second capacitor C2, and a +5V voltage, the negative electrode of the first electrolytic capacitor C1 and the other end of the second capacitor C2 are grounded, Pin 3 of the dual operational amplifier LMH6612 is connected to one end of the first resistor R1, one end of the first inductor L1, and one end of the fourth capacitor C4, the other end of the first resistor R1 is connected to the input signal end, the other end of the first inductor L1 and the other end of the fourth capacitor C4 are both grounded, and the dual operational amplifier Pin 4 of LMH6612 is connected to one end of the third capacitor C3 and a -5V voltage, and the other end of the third capacitor C3 is grounded. Pin 2 of the dual operational amplifier LMH6612 is connected to one end of the second resistor R2 and one end of the third resistor R3. The other end of the second resistor R2 is grounded, and the other end of the third resistor R3 is connected to pin 1 of the dual operational amplifier LMH6612 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to pin 5 of the dual operational amplifier LMH6612, one end of the second inductor L2, and one end of the fifth capacitor C5. The other end of the second inductor L2 and the other end of the fifth capacitor C5 are grounded. Pin 6 of the dual operational amplifier LMH6612 is connected to one end of the fifth resistor R5 and one end of the sixth resistor R6. The other end of the fifth resistor R5 is grounded, and the other end of the sixth resistor R6 is connected to pin 7 of the dual operational amplifier LMH6612 and the signal output end.

[0089] Preferably, in some embodiments, combined Figure 5The SDI-12 communication module is a level logic conversion circuit between the UART of the FPGA and the SDI-12, including a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a three-state buffer SN74LVC1G240DBVRU1, a field effect transistor BSS138Q1, a slide switch SW1, a sixth capacitor C6, and a voltage regulator diode BZX84C7V5LT1GD1; Pin 1 of the tri-state buffer SN74LVC1G240U1 is connected to the control end of the FPGA, pin 2 of the tri-state buffer SN74LVC1G240U1 is connected to the UART_TX end of the FPGA, pin 3 of the tri-state buffer SN74LVC1G240U1 is grounded, pin 5 of the tri-state buffer SN74LVC1G240U1 is connected to a +5V voltage, pin 4 of the tri-state buffer SN74LVC1G240U1 is connected to one end of the eighth resistor R8 and the field effect transistor BSS138 The pin 1 of the eighth resistor R8 is connected to the positive electrode of the voltage-stabilizing diode BZX84C7V5LT1GD1 and one end of the ninth resistor R9, the negative electrode of the voltage-stabilizing diode BZX84C7V5LT1GD1 is grounded, the other end of the ninth resistor R9 is connected to the pin 2 of the slide switch SW1, the pin 2 of the field effect tube BSS138Q1 is connected to one end of the seventh resistor R7 and the UART_RX end of the FPGA, the pin 3 of the field effect tube BSS138Q1 is grounded, and the The other end is connected to +3.3V, pin 1 of the sliding switch SW1 is connected to one end of the tenth resistor R10, the other end of the tenth resistor R10 is connected to one end of the eleventh resistor R11, one end of the twelfth resistor R12, one end of the thirteenth resistor R13, and one end of the sixth capacitor C6, the other end of the eleventh resistor R11 is connected to pin 3 of the sliding switch SW1, the other end of the twelfth resistor R12 and the other end of the sixth capacitor C6 are grounded, and the other end of the thirteenth resistor R13 is connected to the SDI-12 communication bus.

[0090] Furthermore, in one of the embodiments, the FPGA control module pre-processes the data, including performing number system conversion and data storage.

[0091] Furthermore, in one of the embodiments, the host computer 7 obtains the sediment concentration of the suspension to be tested by a method including but not limited to a table lookup method.

[0092] Here, the table lookup method is to look up a data table of a scattering voltage-concentration measurement model.

[0093] The data table of the scattering voltage-concentration measurement model is obtained through calibration, and specifically includes:

[0094] The standard scattering voltage value and acoustic attenuation coefficient of suspensions of different concentrations are measured, and the upper computer fits the data to obtain the functional relationship between the scattering voltage and the concentration, and the functional relationship between the acoustic attenuation coefficient and the concentration;

[0095] The functional relationship between scattering voltage and concentration is corrected by the acoustic attenuation coefficient, and a scattering voltage-concentration measurement model is obtained.

[0096] In one embodiment, a method for measuring sediment concentration by combining ultrasonic backscattering and reflection is provided, the method comprising:

[0097] Add the calibrated suspension and immerse the ultrasonic underwater measuring device in water to fix it;

[0098] After the circuits are connected, the external power supply is turned on, and the power module in the circuit box 1 starts to supply power to the other modules;

[0099] The FPGA control module generates a discontinuous PWM square wave pulse, performs power amplification through the transducer driving module, and drives the ultrasonic transducer 3 to emit ultrasonic waves;

[0100] The ultrasonic transducer 3 receives the sound wave signals backscattered by the suspended particles in the suspension and the echo signals reflected by the reflecting wall 4, and converts these signals into electrical signals;

[0101] The signal receiving and conditioning module amplifies and filters the electrical signal;

[0102] The host computer sends a collection command, and the FPGA control module drives the data collection module to start collecting data. The obtained data is pre-processed in the FPGA control module and then transmitted to the remote host through the SDI-12 communication module;

[0103] The USB conversion port 6 in the remote host converts the data into USB protocol and transmits it to the host computer 7;

[0104] Observe and save the data displayed by the host computer 7, obtain multiple sets of scattering voltage and echo amplitude data at the calibration concentration, obtain the standard scattering voltage value and standard echo amplitude at the calibration concentration by taking the root mean square, and calculate the acoustic attenuation coefficient using the standard echo amplitude data;

[0105] The sediment concentration in the suspension was changed, and the above steps were repeated to obtain the standard scattering voltage value and attenuation coefficient at different concentrations. The Origin data fitting was used to obtain the fitting relationship between concentration-standard scattering voltage and concentration-attenuation coefficient.

[0106] The concentration-standard scattering voltage fitting curve is corrected by the acoustic attenuation coefficient to obtain the scattering voltage-concentration measurement model, which is then stored in the host computer.

[0107] Through the above process, the unknown sediment concentration suspension is measured using but not limited to the table lookup method.

[0108] As a specific example, the present invention is further verified and explained.

[0109] Combination Figure 6 and Figure 7 , taking the laboratory environment as the benchmark, the specific process of the present invention is described as follows:

[0110] (1) Preparation stage: Build a water tank that simulates an actual river, and configure the suspension concentration to start from 0g / L and increase by 10g / L each time until the concentration reaches 120g / L, for a total of thirteen portions of standard sediment suspension. After assembling the underwater measuring device, use a waterproof cable to connect it to the circuit box, immerse it in water, and fix it. Use a cable to connect the remote host end to the other end of the circuit box, turn on the host computer and power the circuit box through an external power supply. Turn on the agitator to stir, calibrate and test the thirteen portions of standard sediment suspension, and obtain the measurement data for Origin data fitting. After correcting the concentration-standard scattering voltage fitting curve by the acoustic attenuation coefficient, it is obtained that the system is in the range of 0 to 120kg / m 3 The measurement curve within the sediment concentration range. When the sediment concentration is 0~30kg / m 3 When the scattering voltage and concentration are in the range of 30-120 kg / m 3 When the scattering voltage is 0.99, the concentration is 0.9960, which is 0.9986. The scattering voltage-concentration curve has goodness of fit in two concentration ranges, which proves that the fitting curve model works well and can be used as a scattering voltage-concentration measurement model for system calibration to obtain the scattering voltage-concentration data table mentioned above, so as to obtain the unknown suspension concentration by the table lookup method in the following measurement experiment.

[0111] (2) Measurement experiment phase: After the preparation work is completed, add the suspension to be tested into the experimental water tank. Turn on the agitator, host computer and power supply again, and the underwater measurement device starts working. The suspension to be tested (such as a river) flows between the probe and the reflective wall. The FPGA module generates 5 2Mhz square wave pulses every 1ms, and drives the probe to emit ultrasonic waves after power amplification through the transducer driver module. The ultrasonic wave is reflected after encountering the reflective wall 6cm in front, and the echo signal is received by the probe. In the propagation process, in addition to reflection, there is also scattering, and the probe receives the scattered signal at the same time. The received signal is converted into a weak electrical signal by the probe. After being processed by the receiving conditioning module (including amplification, filtering, etc.), the processed signal (analog signal) is converted into a digital signal by the FPGA control data acquisition module. After the FPGA converts the collected data into digital system and stores it through FIFO, it is transmitted over long distances through the SDI-12 communication module. Finally, the USB conversion port is used to transfer the data to the host computer at the remote host end. The host computer displays the concentration detection results of the suspension to be tested in real time based on the data table of the scattering voltage-concentration measurement model obtained in the preparation stage.

[0112] In summary, the present invention can be used for sediment concentrations ranging from 0 to 120 kg / m 3 The system can conduct real-time sediment concentration measurement in unknown rivers, which has the advantages of continuous data collection, obtaining sediment concentration information with high temporal and spatial resolution, and wide applicability.

[0113] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Without departing from the spirit and scope of the present invention, any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sediment concentration measurement system combining ultrasonic backscattering and reflection, characterized in that: The system comprises an ultrasonic underwater measuring device, a circuit box (1) and a remote host terminal; The ultrasonic underwater measuring device comprises a fixing rod (2), an ultrasonic transducer (3), a reflecting wall (4), and a distance control track (5) arranged between the ultrasonic transducer (3) and the reflecting wall (4); The circuit box (1) is provided with a transducer driving module, a signal receiving and conditioning module, a data acquisition module, an FPGA control module, a power supply module and an SDI-12 communication module; the remote host end includes a USB conversion port (6) and a host computer (7); The ultrasonic transducer (3) is connected to the transducer driving module and the signal receiving and conditioning module in the circuit box (1) via a waterproof cable (8); the FPGA control module is connected to the other modules for overall control and data processing of the system; the USB conversion port (6) is connected to the SDI-12 communication module via a cable (9); The fixing rod (2) is used to fix the ultrasonic underwater measuring device in the suspension; The ultrasonic transducer (3) is used to transmit ultrasonic waves to the suspended liquid and receive scattered signals; The reflecting wall (4) is used to reflect the ultrasonic signal to generate an echo signal; The distance control track (5) is used to adjust and control the distance between the ultrasonic transducer (3) and the reflection wall (4); The transducer driving module is used to amplify the power of the discontinuous PWM pulses output by the FPGA control module to ensure that the ultrasonic transducer (3) emits ultrasonic waves in an optimal state; The signal receiving and conditioning module is used to process the scattered signals and echo signals received by the ultrasonic transducer (3), including signal amplification and filtering; The data acquisition module is used to convert the analog signal output by the signal receiving and conditioning module into a digital signal and transmit the data to the FPGA control module; The FPGA control module is used to generate PWM drive pulses, receive commands from the host computer, perform data preprocessing, and control the work of other modules; The power supply module is used to convert the voltage of the external power supply into the working voltage required by other modules for power supply; The SDI-12 communication module is used to transmit data received from the FPGA control module to a remote host terminal through the SDI-12 communication protocol, or to transmit commands from the remote host terminal to the FPGA control module; The USB conversion port (6) is used to convert data transmitted over a long distance using the SDI-12 communication protocol into USB protocol data and transmit the data to the host computer; The host computer (7) is used to process the data to obtain the sediment concentration of the suspension to be tested.

2. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 1 is characterized in that: The ultrasonic transducer (3) and one end of the distance control track (5) are fixed to the fixing rod (2), and the reflecting wall (4) is fixed to the other end of the distance control track (5) and is flush with the ultrasonic probe surface of the ultrasonic transducer (3).

3. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 1 is characterized in that: The signal receiving and conditioning module includes an mV-level signal amplifying circuit, a high-pass filtering circuit, and a band-pass filtering circuit composed of LC resonance, which are connected in sequence; The mV-level signal amplification circuit is used to amplify the scattered signal to a preset certain range; The high-pass filter circuit is used to filter out low-frequency noise and power frequency interference in the signal; The bandpass filter circuit is used to filter out high and low frequency interference signals other than the modulation center frequency.

4. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 3 is characterized in that: The bandpass filter circuit composed of LC resonance comprises a dual operational amplifier LMH6612, a first inductor (L1), a second inductor (L2), a first electrolytic capacitor (C1), a second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4), a fifth capacitor (C5), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5) and a sixth resistor (R6); a pin 8 of the dual operational amplifier LMH6612 is connected to the positive electrode of the first electrolytic capacitor (C1), one end of the second capacitor (C2) and a +5V voltage, a negative electrode of the first electrolytic capacitor (C1) and the other end of the second capacitor (C2) are grounded, a pin 3 of the dual operational amplifier LMH6612 is connected to one end of the first resistor (R1), one end of the first inductor (L1) and one end of the fourth capacitor (C4), the other end of the first resistor (R1) is connected to the input signal end, and the other end of the first inductor (L1) and the other end of the fourth capacitor (C4) are both grounded. Pin 4 of the dual operational amplifier LMH6612 is connected to one end of the third capacitor (C3) and a -5V voltage, the other end of the third capacitor (C3) is grounded, pin 2 of the dual operational amplifier LMH6612 is connected to one end of the second resistor (R2) and one end of the third resistor (R3), the other end of the second resistor (R2) is grounded, the other end of the third resistor (R3) is connected to pin 1 of the dual operational amplifier LMH6612 and one end of the fourth resistor (R4), the other end of the fourth resistor (R4) is connected to pin 5 of the dual operational amplifier LMH6612, one end of the second inductor (L2), and one end of the fifth capacitor (C5), the other end of the second inductor (L2) and the other end of the fifth capacitor (C5) are grounded, pin 6 of the dual operational amplifier LMH6612 is connected to one end of the fifth resistor (R5) and one end of the sixth resistor (R6), the other end of the fifth resistor (R5) is grounded, and the other end of the sixth resistor (R6) is connected to pin 7 of the dual operational amplifier LMH6612 and a signal output end.

5. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 1 is characterized in that: The SDI-12 communication module is a level logic conversion circuit between the UART of the FPGA and the SDI-12, including a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a twelfth resistor (R12), a thirteenth resistor (R13), a three-state buffer SN74LVC1G240DBVR (U1), a field effect transistor BSS138 (Q1), a slide switch (SW1), a sixth capacitor (C6), a voltage regulator diode BZX84C7V5LT1G (D1 ); Pin 1 of the tri-state buffer SN74LVC1G240 (U1) is connected to the control end of the FPGA, Pin 2 of the tri-state buffer SN74LVC1G240 (U1) is connected to the UART_TX end of the FPGA, Pin 3 of the tri-state buffer SN74LVC1G240 (U1) is grounded, Pin 5 of the tri-state buffer SN74LVC1G240 (U1) is connected to a +5V voltage, Pin 4 of the tri-state buffer SN74LVC1G240 (U1) is connected to one end of the eighth resistor (R8) and the end of the field effect transistor BSS138 (Q1) The other end of the eighth resistor (R8) is connected to the positive electrode of the voltage-stabilizing diode BZX84C7V5LT1G (D1) and one end of the ninth resistor (R9), the negative electrode of the voltage-stabilizing diode BZX84C7V5LT1G (D1) is grounded, the other end of the ninth resistor (R9) is connected to the pin 2 of the slide switch (SW1), the pin 2 of the field effect transistor BSS138 (Q1) is connected to one end of the seventh resistor (R7) and the UART_RX end of the FPGA, the pin 3 of the field effect transistor BSS138 (Q1) is grounded, and the other end of the seventh resistor (R7 ... and the other end of the seventh resistor (R7) is connected to the pin 2 of the slide switch (SW1). connected to +3.3V, pin 1 of the slide switch (SW1) is connected to one end of the tenth resistor (R10), the other end of the tenth resistor (R10) is connected to one end of the eleventh resistor (R11), one end of the twelfth resistor (R12), one end of the thirteenth resistor (R13), and one end of the sixth capacitor (C6), the other end of the eleventh resistor (R11) is connected to pin 3 of the slide switch (SW1), the other end of the twelfth resistor (R12) and the other end of the sixth capacitor (C6) are grounded, and the other end of the thirteenth resistor (R13) is connected to the SDI-12 communication bus.

6. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 1 is characterized in that: The FPGA control module pre-processes the data, including number system conversion and data storage.

7. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 1 is characterized in that: The host computer (7) obtains the sediment concentration of the suspension to be tested by a method including but not limited to a table lookup method.

8. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 7 is characterized in that: The table lookup method is to query the data table of the scattering voltage-concentration measurement model.

9. The sediment concentration measurement system combining ultrasonic backscattering and reflection according to claim 8 is characterized in that: The data table of the scattering voltage-concentration measurement model is obtained through calibration, and specifically includes: The standard scattering voltage value and acoustic attenuation coefficient of suspensions of different concentrations are measured, and the upper computer fits the data to obtain the functional relationship between the scattering voltage and the concentration, and the functional relationship between the acoustic attenuation coefficient and the concentration; The functional relationship between scattering voltage and concentration is corrected by the acoustic attenuation coefficient, and a scattering voltage-concentration measurement model is obtained.

10. A sediment concentration measurement method based on the system of any one of claims 1 to 9 combining ultrasonic backscattering and reflection, characterized in that: The method comprises: Add the calibrated suspension and immerse the ultrasonic underwater measuring device in water to fix it; After the circuits are connected, the external power supply is turned on, and the power module in the circuit box (1) starts to supply power to the remaining modules; The FPGA control module generates discontinuous PWM square wave pulses, performs power amplification through the transducer drive module, and drives the ultrasonic transducer (3) to emit ultrasonic waves; The ultrasonic transducer (3) receives the sound wave signals backscattered by the suspended particles in the suspension and the echo signals reflected by the reflecting wall (4), and converts these signals into electrical signals; The signal receiving and conditioning module amplifies and filters the electrical signal; The host computer sends a collection command, and the FPGA control module drives the data collection module to start collecting data. The obtained data is pre-processed in the FPGA control module and then transmitted to the remote host through the SDI-12 communication module; The USB conversion port (6) in the remote host converts the data into USB protocol and transmits it to the host computer (7); Observe and save the data displayed by the host computer (7), obtain multiple sets of scattering voltage and echo amplitude data at the calibration concentration, obtain the standard scattering voltage value and the standard echo amplitude at the calibration concentration by taking the root mean square, and calculate the acoustic attenuation coefficient using the standard echo amplitude data; The sediment concentration in the suspension was changed, and the above steps were repeated to obtain the standard scattering voltage value and attenuation coefficient at different concentrations, and the fitting relationship between concentration-standard scattering voltage and concentration-attenuation coefficient was obtained through data fitting; The concentration-standard scattering voltage fitting curve is corrected by the acoustic attenuation coefficient to obtain the scattering voltage-concentration measurement model, which is then stored in the host computer. Through the above process, the unknown sediment concentration suspension is measured using but not limited to the table lookup method.

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