An acoustic-optic fusion river sediment concentration and particle size measuring device and method

Abstract

The application provides a kind of acoustic-optical fusion river sediment concentration particle size measuring device and method, belong to sediment monitoring technical field, including optical unit, acoustic unit, FPGA processing unit, display unit and power supply unit;Optical unit is arranged by photodiode of 90 ° and 135 ° and acquires double-angle optical scattering signal;Acoustic unit obtains ultrasonic signal by ultrasonic emission and receiving probe;FPGA processing unit carries out normalized difference processing to double-angle optical scattering signal and inverts sediment particle size, extracts attenuation characteristics to ultrasonic signal to invert acoustic concentration, and combines the optical concentration reference value of double-angle scattering light signal, according to weight function, acoustic concentration and optical concentration reference value are weighted fusion, obtain sediment concentration and particle size.The application solves the problem that the precision of sediment particle size measurement and the adaptability of complex water environment are insufficient due to the single sensor measurement being easily disturbed and the lack of effective fusion of acoustic-optical data in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of sediment monitoring technology, and in particular relates to a sound-optical fusion device and method for measuring river sediment concentration and particle size. Background Technology

[0002] The concentration and particle size distribution of river sediment are core foundational data for soil and water conservation, river and lake management, safe operation of water conservancy projects, and ecological environment assessment. Traditional sediment measurement methods mainly rely on manual sampling and laboratory analysis, which are not only time-consuming and labor-intensive with low monitoring frequency, but also fail to reflect the spatiotemporal distribution characteristics of sediment through single-point sampling, resulting in significant deficiencies in timeliness and representativeness. With the development of sensor technology, optical and acoustic methods have gradually become the mainstream online monitoring methods.

[0003] Optical methods, based on the principle of light scattering, invert sediment particle size and concentration by collecting scattered light signals. However, optical signals from a single angle are easily affected by water transparency, plankton, and high sediment content, and have limited penetration in high-concentration water, making it difficult to balance measurement range and accuracy. Acoustic methods, based on the attenuation characteristics of sound waves in sediment-laden water, have the advantages of strong penetration and wide applicability. However, they are easily affected by temperature, flow velocity, air bubbles, and sediment particle size distribution, resulting in insufficient stability in complex aquatic environments. While existing technologies have attempted to combine acoustic and optical technologies for sediment monitoring, most only achieve simple data superposition without establishing a scientific signal fusion model and failing to fully utilize the particle size resolution capability of multi-angle optical scattering. Furthermore, data processing often relies on traditional physical models or cloud computing resources, exhibiting poor adaptability to nonlinear and complex aquatic environments, making it difficult to achieve low-power, real-time, high-precision measurements in the field. Summary of the Invention

[0004] To address the aforementioned shortcomings in existing technologies, this invention provides an acoustic-optical fusion-based device and method for measuring river sediment concentration and particle size. By performing specialized processing on dual-angle light scattering signals and ultrasonic attenuation signals and employing decision-level weighted fusion inversion, it achieves high-precision, real-time, and highly adaptable synchronous measurement of multiple sediment parameters. This solves the problems in existing technologies where single-sensor measurements are easily interfered with, and the lack of an effective fusion mechanism due to the simple superposition of acoustic and optical data leads to insufficient accuracy in sediment particle size measurement and adaptability to complex aquatic environments.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a sound and light fusion river sediment concentration and particle size measurement device, comprising an optical unit, an acoustic unit, an FPGA processing unit connected to the optical unit and the acoustic unit respectively, a display unit connected to the FPGA processing unit, and a power supply unit; The optical unit includes an analog-to-digital converter (ADC), a first active filter module, a second active filter module, a first amplifier circuit module, a second amplifier circuit module, a laser driver module, a laser, a first photodiode, a second photodiode, and an optical bracket. The ADC is connected to both the first and second active filter modules. The first active filter module is sequentially connected to the first amplifier circuit module and the first photodiode. The second active filter module is sequentially connected to the second amplifier circuit module and the second photodiode. The laser driver module is connected to the laser. The first photodiode is positioned at a 90° angle to the laser's light emission direction, and the second photodiode is positioned at a 135° angle to the laser's light emission direction. The laser driver module is connected to a power supply unit. The laser, the first photodiode, and the second photodiode are all mounted on the optical bracket. Both the ADC and the laser driver module are connected to an FPGA processing unit. The acoustic unit includes an ultrasonic probe bracket, a digital-to-analog (DAC) converter module, an ultrasonic receiving probe, and an ultrasonic transmitting probe. The DAC module is connected to both the ultrasonic transmitting probe and the ultrasonic receiving probe, which are both mounted on the ultrasonic probe bracket. The DAC module is also connected to an FPGA processing unit. The FPGA processing unit includes an FPGA development board and GPIO ports, pin headers, a power interface, and a switch disposed thereon. The FPGA development board is connected to the analog-to-digital conversion module via pin headers, and to the laser driver module via GPIO ports. The FPGA development board is also connected to the power supply unit. The display unit includes an LCD screen, which is connected to the FPGA development board via a connection interface. The power supply unit includes a first power supply module and a second power supply module. The first power supply module is connected to the FPGA development board, the first active filter module and the second active filter module, respectively. The second power supply module is connected to the first amplifier circuit module, the second amplifier circuit module and the laser driver module, respectively.

[0006] In existing methods for measuring river sediment concentration and particle size, optical measurement methods are sensitive to changes in particle size, but light attenuates quickly and has limited penetration in high-concentration sediment-laden water, thus limiting the measurement range. While single ultrasonic measurement methods have a wide measurement range, they are easily affected by environmental factors such as water temperature, flow velocity, and air bubbles, and their ability to distinguish changes in sediment particle size is insufficient. While existing technologies attempt to combine acoustic and optical technologies for sediment measurement, the field has long faced a technical bottleneck: "signals with vastly different response mechanisms, making synergistic fusion difficult." Optical signals are highly sensitive to low-concentration, fine-grained sediment but are easily limited by concentration, while ultrasonic signals are highly adaptable to high-concentration, coarse-grained sediment but have weak particle size resolution. The response characteristics and interference factors of the two technologies to sediment parameters are completely different, making it difficult to establish accurate synergistic inversion models. Therefore, most industry practices simply superimpose the results of acoustic and optical signals without performing separate processing for the different response characteristics of sediment particle size and concentration. This fails to fully explore the particle size resolution potential of multi-angle optical scattering and lacks a scientifically effective acoustic-optical fusion inversion mechanism, resulting in persistently low measurement accuracy and stability in complex, nonlinear, and time-varying aquatic environments. Furthermore, existing fusion solutions often rely on host computers or cloud computing power to complete complex data processing, making it difficult to achieve lightweight, real-time fusion inversion on embedded hardware platforms and failing to meet the monitoring needs of field rivers.

[0007] This invention overcomes the technical bottleneck of "difficulty in coordinating and fusing acoustic and optical signals." Utilizing the core characteristics of "optical signals excelling at particle size resolution and ultrasonic signals excelling at concentration detection," it employs a dual-angle optical scattering signal acquisition structure (90° and 135°) combined with normalized differential features for particle size inversion. This effectively counteracts light source fluctuations and ambient light interference, significantly improving the accuracy of sediment particle size measurement. Simultaneously, it utilizes ultrasonic attenuation signals to invert acoustic concentration, combining this with optical concentration estimates obtained from dual-angle optical signals. Weighted fusion is then performed based on a pre-stored weighting function, and the fusion weights are dynamically adjusted according to different concentration ranges. This achieves a complementary advantage of the wide measurement range of acoustic methods and the high sensitivity at low concentrations of optical methods, solving the fusion problem caused by significant differences in the response mechanisms of acoustic and optical signals. Furthermore, this invention pre-stores the particle size inversion mapping, concentration inversion mapping, and weighting function in the form of a lookup table or piecewise linear model on the FPGA. In the development board, all signal processing and fusion calculations are completed on the embedded hardware, without relying on cloud or host computer computing power. It features fast response speed and low power consumption, and can be directly deployed in the field. Ultimately, it solves the problems of low measurement accuracy, poor environmental adaptability and weak real-time performance in existing technologies, and realizes integrated, high-precision, real-time online monitoring of river sediment concentration and particle size.

[0008] Furthermore: in the optical unit, the first photodiode and the second photodiode respectively acquire 90° simulated scattered light signals and 135° simulated scattered light signals; The first amplifier circuit module and the first active filter module amplify and filter the 90° analog scattered light signal, and transmit it to the analog-to-digital conversion module for analog-to-digital conversion to obtain the 90° digital scattered light signal; The second amplifier circuit module and the second active filter module amplify and filter the 135° analog scattered light signal, and transmit it to the analog-to-digital conversion module for analog-to-digital conversion to obtain the 135° digital scattered light signal; The analog-to-digital conversion module transmits the 90° digital scattered light signal and the 135° digital scattered light signal to the FPGA development board; The laser driver module receives the modulation signal output by the FPGA development board and drives the laser to emit laser light according to the modulation signal.

[0009] The further beneficial effects mentioned above are as follows: By setting up a dual-angle optical scattering acquisition structure at 90° and 135° and using a modulated signal to drive the laser instead of a single-angle optical signal, the present invention can solve the problem of low measurement accuracy caused by the large influence of suspended sediment concentration and strong background stray light interference on the scattered light signal in the water environment; through dual-angle differential processing, the common-mode interference caused by water background scattering and water flow fluctuations is reduced, and the particle size resolution and measurement stability in complex sediment water environments are improved.

[0010] Furthermore: In the acoustic unit, the digital-to-analog converter module outputs an analog excitation signal under the control of the FPGA development board to drive the ultrasonic transmitting probe to emit ultrasonic waves. The ultrasonic receiving probe receives the ultrasonic waves after they have been attenuated by water and converts them into ultrasonic analog signals. The digital-to-analog converter module performs analog-to-digital conversion on the ultrasonic analog signals to obtain ultrasonic digital signals, which are then transmitted to the FPGA development board.

[0011] The further beneficial effects mentioned above are as follows: Addressing the issue that ultrasonic signals in river sediment environments are easily interfered with by factors such as temperature, flow velocity, and bubbles, a stable frequency excitation signal is generated by an FPGA development board to drive the ultrasonic probe to emit, and the digital-to-analog-to-digital converter is controlled to sample the received acoustic signal synchronously. This solves the problem of accurately acquiring ultrasonic attenuation signals in complex water environments; reduces the problem of low signal acquisition quality caused by waveform distortion and amplitude fluctuations of ultrasonic attenuation signals in complex water environments, and enables the acquisition of stable and reliable ultrasonic receiving signals.

[0012] Furthermore: the workflow of the FPGA processing unit includes: It can receive 90° digital scattered light signals, 135° digital scattered light signals, and ultrasonic receiving signals; Normalized differential processing was performed on the 90° and 135° digital scattered light signals, and particle size sensitive features were extracted. Combined with the pre-stored sediment particle size inversion mapping in the FPGA development board, the sediment particle size was obtained. The attenuation characteristics of the ultrasonic received signal are extracted and combined with the acoustic concentration inversion mapping pre-stored in the FPGA development board to obtain the acoustic concentration. Based on the intensity information of the 90° and 135° digital scattered light signals, and combined with the optical density reference mapping pre-stored in the FPGA development board, the optical density reference value is obtained. The acoustic and optical concentration reference values ​​are weighted and fused according to the weighting function stored in the FPGA development board to output the sediment concentration.

[0013] Current acoustic-optical fusion techniques for measuring river sediment concentration based on particle size distribution rely on simplistic signal processing. They fail to address the different response characteristics of sediment particle size and concentration, hindering the full utilization of the respective advantages of acoustic and optical methods. Furthermore, in complex aquatic environments, it remains difficult to balance the accuracy of sediment particle size retrieval with the measurement range of sediment concentration. Additionally, a lightweight fusion mechanism capable of real-time operation on embedded platforms is lacking. This invention extracts attenuation characteristics from ultrasonic attenuation signals to derive acoustic concentration, while simultaneously using dual-angle optical scattering signals to obtain optical concentration estimates. Based on these estimates, a weighted fusion is performed using a pre-stored weighting function. This leverages the complementary advantages of the acoustic method's wide measurement range and the optical method's high sensitivity at low concentrations, enabling real-time on-site measurement in complex sediment-laden river environments. This improves the device's response speed, environmental adaptability, and reliability in field deployment.

[0014] This invention also provides a method for measuring river sediment concentration and particle size using an acoustic-optical fusion method, comprising: The river sediment concentration and particle size measuring device is placed in the water body to be measured and powered by the power supply unit to complete the device initialization.

[0015] A 1 kHz square wave modulation signal is output through the FPGA development board to drive the laser to emit laser light. Based on the laser emitted by the laser, the two photodiodes of the optical unit collect the 90° analog scattered light signal and the 135° analog scattered light signal respectively, and then amplify, filter and convert the signal to digital to obtain the 90° digital scattered light signal and the 135° digital scattered light signal. The analog-to-digital converter module is controlled by an FPGA development board to output an analog excitation signal, which drives the ultrasonic transmitting probe to emit ultrasonic waves into the water body to be tested. The ultrasonic receiving probe then acquires the ultrasonic waves after they have been attenuated by the water body to obtain the ultrasonic receiving signal. Based on the 90° digital scattered light signal, the 135° digital scattered light signal, and the ultrasonic received signal, the FPGA development board performs split processing and weighted fusion based on the pre-stored sediment parameter inversion mapping and acousto-optic fusion calculation parameters to obtain the sediment concentration and sediment particle size.

[0016] Further: obtaining the sediment concentration and sediment particle size specifically includes: Based on the 90° and 135° digital scattered light signals, a weighted normalized differential feature is constructed, and sediment particle size inversion mapping is performed to obtain the sediment particle size. The optical characteristic intensity is obtained by weighting the 90° and 135° digital scattered light signals and performing an optical concentration reference mapping to obtain an optical concentration estimate. Based on the received ultrasonic signal, acoustic attenuation characteristics are constructed by extracting peak-to-peak values, and acoustic concentration reference mapping is performed to obtain an acoustic concentration estimate. The sediment concentration is obtained by weighted fusion calculation based on optical and acoustic concentration estimates.

[0017] Furthermore, the expression for the particle size of the sediment is as follows:

[0018]

[0019] in, The particle size of the sediment This is the sediment particle size inversion mapping function. For normalized difference features, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. This is a preset minimum constant.

[0020] Furthermore, the expression for the sediment concentration is as follows:

[0021]

[0022]

[0023]

[0024]

[0025] in, The concentration of sediment. As weight, For acoustic concentration estimation, This is an optical concentration reference value. For optical concentration reference mapping function, For optical characteristic intensity, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. and These are the weighting coefficients for optical characteristics. This is the acoustic concentration inversion mapping function. Acoustic attenuation characteristics, This represents the peak-to-peak value of the received ultrasonic signal. This is the reference peak value for clear water. It is the natural logarithm function.

[0026] The beneficial effects of this invention are as follows: This invention utilizes the coordinated measurement of dual-angle optical scattering and ultrasonic attenuation signals, employing a path-specific processing approach to address the different response characteristics of particle size and concentration. Particle size is obtained by constructing normalized differential features from the dual-angle optical scattering signals and then inverting them. Concentration is obtained by inverting the acoustic concentration from the ultrasonic attenuation features and combining it with optical concentration reference values ​​for decision-level weighted fusion. The inversion mapping and weighting function are embedded in an FPGA development board in the form of a lookup table, a piecewise linear model, and its parameters, enabling real-time calculations on-site without relying on cloud or host computer computing power. The device boasts high integration, strong anti-interference capabilities, and is suitable for field river monitoring conditions. Attached Figure Description

[0027] Figure 1 A schematic diagram of a sound-optical fusion device for measuring river sediment concentration and particle size; The components include: First active filter module—1, Second active filter module—2, First power supply module—3, Second power supply module—4, GPIO port—5, LCD screen—6, Connection interface—7, Pin header—8, Power interface—9, Switch—10, Analog-to-digital converter module—11, Ultrasonic probe bracket—12, Ultrasonic receiving probe—13, First amplifier circuit module—14, Second amplifier circuit module—15, Digital-to-analog and analog-to-digital converter module—16, Laser driver module—17, Laser—18, First photodiode—19, Second photodiode—20, Optical bracket—21, FPGA development board—22, and Ultrasonic transmitting probe—23. Detailed Implementation

[0028] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0029] Example 1 like Figure 1 The diagram shows a schematic of a sound-optic fusion river sediment concentration and particle size measurement device. The present invention provides a sound-optic fusion river sediment concentration and particle size measurement device, including an optical unit, an acoustic unit, an FPGA processing unit connected to the optical unit and the acoustic unit respectively, a display unit connected to the FPGA processing unit, and a power supply unit. The optical unit includes an analog-to-digital converter module 11, a first active filter module 1, a second active filter module 2, a first amplifier circuit module 14, a second amplifier circuit module 15, a laser driver module 17, a laser 18, a first photodiode 19, a second photodiode 20, and an optical support 21. The analog-to-digital converter module 11 is connected to the first active filter module 1 and the second active filter module 2. The first active filter module 1 is connected to the first amplifier circuit module 14 and the first photodiode 19 in sequence, and the second active filter module 2 is connected to the second amplifier circuit module 15 in sequence. The laser driver module 17 is connected to the laser 18 and the second photodiode 20. The first photodiode 19 is positioned at a 90° angle to the light emission direction of the laser 18, and the second photodiode 20 is positioned at a 135° angle to the light emission direction of the laser 18. The laser driver module 17 is connected to the power supply unit. The laser 18, the first photodiode 19, and the second photodiode 20 are all mounted on the optical bracket 21. The analog-to-digital conversion module 11 and the laser driver module 17 are both connected to the FPGA processing unit. The acoustic unit includes an ultrasonic probe bracket 12, a digital-to-analog (D / A) converter module 16, an ultrasonic receiving probe 13, and an ultrasonic transmitting probe 23. The D / A converter module 16 is connected to the ultrasonic transmitting probe 23 and the ultrasonic receiving probe 13, respectively. Both the ultrasonic transmitting probe 23 and the ultrasonic receiving probe 13 are mounted on the ultrasonic probe bracket 12. The D / A converter module 16 is connected to the FPGA processing unit. The FPGA processing unit includes an FPGA development board 22 and GPIO ports 5, pin headers 8, power interfaces 9 and switches 10 disposed thereon. The FPGA development board 22 is connected to the analog-to-digital conversion module 11 through the pin headers 8. The FPGA development board 22 is connected to the laser driver module 17 through the GPIO port 5. The FPGA development board 22 is also connected to the power supply unit. The display unit includes an LCD screen 6, which is connected to the FPGA development board 22 via a connection interface 7. The power supply unit includes a first power supply module 3 and a second power supply module 4. The first power supply module 3 is connected to the FPGA development board 22, the first active filter module 1 and the second active filter module 2, respectively. The second power supply module 4 is connected to the first amplifier circuit module 14, the second amplifier circuit module 15 and the laser driver module 17, respectively.

[0030] Existing sediment measurement technologies each have their limitations: optical methods offer high accuracy, but light attenuates rapidly in sediment-laden water, resulting in a narrow measurement range; gravimetric methods offer excellent accuracy but are slow and cannot achieve real-time monitoring of sediment concentration; satellite remote sensing relies on observation models to retrieve concentrations, and its accuracy is significantly affected by the model and has low universality, requiring separate models for different water bodies; isotope methods offer high accuracy but are limited by the scarcity of radioactive sources, and radioactivity can pollute water bodies; while acoustic methods offer a wide measurement range, they suffer from low measurement accuracy.

[0031] To address the aforementioned issues, this invention employs an acoustic-optical fusion scheme for precise measurement: An acoustic unit measures the attenuation of ultrasonic waves in the river to ensure a wide concentration measurement range; simultaneously, dual-angle optical scattering signals are introduced to enhance the resolution of sediment particle size, and particle size inversion mapping, acoustic concentration inversion mapping, and optical concentration reference mapping are established based on pre-stored data; during on-site measurement, the FPGA extracts normalized differential features from the optical signal to invert particle size, extracts attenuation features from the ultrasonic signal to invert acoustic concentration, and performs decision-level weighted fusion of acoustic and optical concentration reference values ​​according to a preset weight function to achieve real-time output of sediment concentration and particle size; the analog-to-digital conversion module, combined with the FPGA processing unit, integrates the acquisition, filtering, fusion processing, and multi-terminal communication functions of dual-angle optical and ultrasonic signals, and the modular integrated design ensures instrument miniaturization and portability, adapting to complex river monitoring conditions in the field.

[0032] In one embodiment of the present invention, in the optical unit, the first photodiode 19 and the second photodiode 20 respectively acquire 90° simulated scattered light signal and 135° simulated scattered light signal; The first amplifier circuit module 14 and the first active filter module 1 amplify and filter the 90° analog scattered light signal, and transmit it to the analog-to-digital conversion module 11 for analog-to-digital conversion to obtain the 90° digital scattered light signal; The second amplifier circuit module 15 and the second active filter module 2 amplify and filter the 135° analog scattered light signal, and transmit it to the analog-to-digital conversion module 11 for analog-to-digital conversion to obtain the 135° digital scattered light signal. The analog-to-digital converter module 11 transmits the 90° digital scattered light signal and the 135° digital scattered light signal to the FPGA development board 22; The laser driver module 17 receives the modulation signal output from the FPGA development board 22 and drives the laser 18 to emit laser light according to the modulation signal. The laser is model YSD85-121 with a wavelength of 850nm, an output power of 10mW, an operating voltage of 5V, and a beam diameter of approximately 1.5mm. The first and second photodiodes are model BPX61 with a spectral range of 400-1100nm, a peak wavelength of 850nm, a typical dark current of 2nA, and a typical responsivity of 0.62A / W (at 850nm). The optical bracket 21 is made of 3D printed PLA material, with a diameter of 107mm and a height of 66.5mm, which fixes the laser and the two photodiodes to ensure that the angular deviation is within ±1°.

[0033] In one embodiment of the present invention, in the acoustic unit, the digital-to-analog (DAC) conversion module 16, under the control of the FPGA development board 22, outputs an analog excitation signal to drive the ultrasonic transmitting probe 23 to emit ultrasonic waves. The ultrasonic receiving probe 13 receives the ultrasonic waves after attenuation by the water body and converts them into ultrasonic receiving signals. The DAC conversion module 16 performs analog-to-digital conversion on the ultrasonic analog signals to obtain ultrasonic digital signals, which are then transmitted to the FPGA development board 22. The ultrasonic probe bracket 12 can fix the ultrasonic transmitting probe 23 and the ultrasonic receiving probe 13, ensuring stable transmission and reception of ultrasonic signals. The DAC conversion module 16 receives the control signal from the FPGA development board 22, completes the analog-to-digital conversion, and outputs a 1MHz excitation signal to drive the ultrasonic transmitting probe 23 to emit ultrasonic waves. The ultrasonic waves propagate and attenuate in the river under test. The ultrasonic receiving probe 13 receives the attenuated ultrasonic signal, and the DAC conversion module 16 completes the analog-to-digital conversion, transmitting the signal to the FPGA development board 22 for subsequent processing.

[0034] The integrated digital-to-analog (D / A) converter module 16 includes a D / A converter chip AD9708 and an analog-to-digital (ADC) converter chip AD9280. AD9708 is an 8-bit D / A converter chip with a sampling rate of 125 MSPS and an output voltage range of -5V to +5V. AD9280 is an 8-bit ADC chip with a sampling rate of 32 MSPS and an input voltage range of -5V to +5V. The ultrasonic transmitting probe 23 is model DYW-1M-01T, with an operating frequency of 1MHz ± 5%, a minimum impedance of 15Ω ± 20%, a half-power angle of (-3dB) 2.4° ± 0.5, and an acuity angle of 5.8° ± 1. The ultrasonic receiving probe 13 is model DYW-01-01E, with a working frequency of 1MHz ± 5%, a minimum impedance of 25Ω ± 20%, a half-power angle of (-3dB) 3.2° ± 1, and an acute angle of 7.5° ± 2. The ultrasonic probe bracket 12 is 3D printed from PLA material, with a length of 135 mm, a width of 70 mm, and a height of 45 mm. Two embedded mounting holes that match the probe's dimensions are pre-designed in the bracket body to embed and fix the ultrasonic transmitting probe 23 and the ultrasonic receiving probe 13. Through structural design constraints, the two probes can naturally achieve end face alignment and coaxiality after assembly, reducing alignment errors caused by manual adjustment.

[0035] In one embodiment of the present invention, the FPGA processing unit includes an FPGA development board and GPIO ports and headers disposed thereon; the GPIO ports output a 1 kHz square wave modulation signal to the laser driver module to drive the laser to work; the headers are used to receive the dual-angle optical scattering signal transmitted by the analog-to-digital conversion module 11; the FPGA development board 22 is also connected to the digital-to-analog and analog-to-digital integrated conversion module 16 to realize the driving control and data reception of the ultrasonic signal. The FPGA development board 22 pre-stores sediment parameter inversion mapping and acoustic-optical fusion calculation parameters. The sediment parameter inversion mapping includes an optical particle size mapping for sediment particle size inversion, and an acoustic concentration mapping and an optical concentration reference mapping for sediment concentration inversion. The acoustic-optical fusion calculation parameters include a weighting function for decision-level weighted fusion of the acoustic concentration result and the optical concentration reference value; wherein, the optical particle size mapping realizes particle size inversion based on the normalized differential characteristics of the dual-angle optical scattering signal, the acoustic concentration mapping realizes concentration inversion based on the ultrasonic attenuation characteristics, and combines the optical concentration reference mapping for weighted fusion in different concentration ranges, thereby outputting sediment concentration and particle size parameters. The FPGA development board 22 is connected to the FPGA development board via a serial port through the analog-to-digital converter module 11, and receives the ultrasonic digital signal output by the analog-to-digital converter module 11 to ensure the stability of signal transmission.

[0036] The solidified form of the sediment parameter inversion mapping is as follows: the "interval threshold + coefficient parameter" of the above three types of functions are stored as three lookup tables (LUTs) and solidified in the on-chip ROM (capacity 512KB) of the FPGA development board (EP4CE10F17C8) to avoid external storage delay; the calling logic is as follows: after the FPGA receives the feature value, it first determines the interval to which it belongs through hardware logic, and then reads the coefficient parameter of the corresponding interval for calculation to ensure that the real-time performance meets the needs of field monitoring.

[0037] Among them, the FPGA development board 22 can use Intel (Altera) FPGA development boards with the main chip being Intel (Altera) Cyclone IV series EP4CE10F17C8; it can also further include other FPGA development boards with similar performance, such as FPGA development boards with chips of EP4CE30, EP4CE40 series, etc., to ensure the accuracy and reliability of the measurement device.

[0038] In one embodiment of the present invention, the display unit includes an LCD screen 6 and a connection interface 7. The connection interface 7 enables signal transmission between the FPGA development board 22 and the LCD screen 6. The LCD screen 6 is used to display the inverted sediment concentration and particle size distribution data in real time, facilitating on-site observation. The LCD screen 6 can be model F043A11-601, with a resolution of 480×272 pixels. Its logic and interface power supply operating voltage is 3.3V. The pixel driving section needs to provide multiple driving voltages such as AVDD, VGH, and VGL, and communicates with the FPGA development board 22 through an RGB parallel interface.

[0039] In one embodiment of the present invention, the power supply unit includes a first power supply module 3 and a second power supply module 4, wherein the first power supply module 3 supplies power to the FPGA development board 22, the first active filter module 1, and the first active filter module 22, with an input voltage of 5V and an output voltage of 12V; the second power supply module 4 supplies power to the first amplifier circuit module 14, the second amplifier circuit module 15, and the laser driver module 17, with an input voltage of 5V and an output voltage of 12V, ensuring stable operation of each unit; the FPGA development board 22 is also provided with a power interface 9 and a switch 10, which are used to realize the power supply access of the FPGA development board and the start and stop control of the overall device.

[0040] The working process of the acoustic-optical fusion river sediment concentration and particle size measurement device of the present invention is as follows: S1. System power-on initialization.

[0041] The power supply unit provides power to the laser driver module, laser, first photodiode, second photodiode, ultrasonic transmitting probe, ultrasonic receiving probe, first active filter module, second active filter module, amplification module, digital-to-analog-to-digital converter module, FPGA processing unit, and display unit, enabling each functional module to enter normal working state; at the same time, the FPGA processing unit completes internal register configuration, lookup table loading, and parameter initialization.

[0042] S2, dual-angle scattered light signal acquisition.

[0043] A laser driver module drives a laser to emit laser light, which irradiates suspended sediment particles in the water body under test to generate scattered light. A first photodiode positioned at 90° receives the 90° scattered light signal, and a second photodiode positioned at 135° receives the 135° scattered light signal. The first and second photodiodes convert the received scattered light signals into corresponding analog electrical signals, which are then filtered by a first and a second active filter module, respectively, before being sent to a digital-to-analog-to-digital converter module to obtain 90° and 135° digital scattered light signals, which are then transmitted to the FPGA processing unit.

[0044] S3, Ultrasonic signal acquisition.

[0045] The ultrasonic transmitting module drives the ultrasonic transmitting probe to emit ultrasonic signals into the water body to be tested. The ultrasonic signals pass through the sediment-containing water body and are received by the ultrasonic receiving probe. The resulting ultrasonic analog signals are sent to the digital-to-analog-to-digital converter module to be converted into ultrasonic digital signals and transmitted to the FPGA processing unit.

[0046] S4, sediment particle size inversion.

[0047] The FPGA processing unit receives the 90° digital scattered light signal and the 135° digital scattered light signal, extracts features from the two digital scattered light signals, and constructs a weighted normalized differential feature. Then, based on the pre-established and stored sediment particle size inversion mapping relationship, it performs mapping calculation on the normalized differential feature to obtain the particle size information of sediment particles in the water body to be tested.

[0048] S5. Calculation of optical concentration reference value.

[0049] The FPGA processing unit extracts optical features based on the 90° and 135° digital scattered light signals, and calculates the optical concentration reference value of the water body to be tested by combining the pre-established and stored optical concentration reference mapping relationship.

[0050] S6. Calculation of acoustic concentration estimates.

[0051] The FPGA processing unit extracts acoustic attenuation features based on the ultrasonic received signal and performs calculations in conjunction with the pre-established and stored acoustic concentration inversion mapping relationship to obtain the estimated acoustic concentration of the water body to be tested.

[0052] S7. Calculation of sediment concentration.

[0053] The FPGA processing unit determines the acoustic-optical fusion weights based on the optical concentration reference values, and uses the acoustic-optical fusion weights to perform weighted fusion of the optical concentration reference values ​​and the acoustic concentration estimates to obtain the sediment concentration measurement results of the water body to be measured.

[0054] S8. Result Output and Display.

[0055] The FPGA processing unit outputs the sediment particle size information and sediment concentration measurement results to the display unit for real-time display, thereby realizing real-time online measurement of sediment concentration and particle size information in river water.

[0056] The beneficial effects of this invention are as follows: This invention uses an optical bracket to fix the laser to a first photodiode and a second photodiode at angles of 90° and 135°, ensuring stable acquisition of dual-angle scattered light signals; an ultrasonic probe bracket to coaxially fix the ultrasonic transmitting probe and ultrasonic receiving probe ensures stable transmission and reception of ultrasonic signals; the optical unit uses a modulation signal to drive the laser and sets up an amplification circuit module and an active filter module to modulate the scattered light signal, suppressing ambient light interference and improving the signal-to-noise ratio; the acoustic unit uses a digital-to-analog-to-digital conversion module, achieving stable transmission and high-speed acquisition of ultrasonic signals under precise control of an FPGA development board, and performs path-specific processing and fusion of the dual-angle scattered light signal and ultrasonic signal using pre-stored data to obtain sediment particle size and sediment concentration; this invention, through modular integration and precise structural fixation, achieves stable acquisition of multiple physical quantity signals in complex river environments, providing a reliable hardware foundation for subsequent high-precision acoustic-optical fusion inversion.

[0057] Example 2 This invention provides a method for measuring river sediment concentration and particle size using an acoustic-optical fusion approach. Based on the river sediment concentration and particle size measuring device described in Example 1, it includes: The river sediment concentration and particle size measuring device is placed in the water body to be measured and powered by the power supply unit to complete the device initialization.

[0058] A 1 kHz square wave modulation signal is output through the FPGA development board to drive the laser to emit laser light. Based on the laser emitted by the laser, the two photodiodes of the optical unit collect the 90° analog scattered light signal and the 135° analog scattered light signal respectively, and then amplify, filter and convert the signal to digital to obtain the 90° digital scattered light signal and the 135° digital scattered light signal. The analog-to-digital converter module is controlled by an FPGA development board to output an analog excitation signal, which drives the ultrasonic transmitting probe to emit ultrasonic waves into the water body to be tested. The ultrasonic receiving probe then acquires the ultrasonic waves after they have been attenuated by the water body to obtain the ultrasonic receiving signal. Based on the 90° digital scattered light signal, the 135° digital scattered light signal, and the ultrasonic received signal, the FPGA development board performs split processing and weighted fusion based on the pre-stored sediment parameter inversion mapping and acousto-optic fusion calculation parameters to obtain the sediment concentration and sediment particle size.

[0059] In one embodiment of the present invention, obtaining the sediment concentration and sediment particle size specifically includes: Based on the 90° and 135° digital scattered light signals, normalized differential features were constructed, and sediment particle size inversion mapping was performed to obtain the sediment particle size. The optical characteristic intensity is obtained by weighting the 90° and 135° digital scattered light signals and performing an optical concentration reference mapping to obtain an optical concentration estimate. Based on the received ultrasonic signal, acoustic attenuation characteristics are constructed by extracting peak-to-peak values, and acoustic concentration reference mapping is performed to obtain an acoustic concentration estimate. The sediment concentration is obtained by weighted fusion calculation based on optical and acoustic concentration estimates.

[0060] In one embodiment of the present invention, the expression for the particle size of sediment is as follows:

[0061]

[0062] in, The particle size of the sediment This is the sediment particle size inversion mapping function. For normalized difference features, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. This is a preset minimum constant.

[0063] In one embodiment of the present invention, the expression for sediment concentration is as follows:

[0064]

[0065]

[0066]

[0067]

[0068] in, The concentration of sediment. As weight, For acoustic concentration estimation, This is an optical concentration reference value. For optical concentration reference mapping function, For optical characteristic intensity, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. and These are the weighting coefficients for optical characteristics. This is the acoustic concentration inversion mapping function. Acoustic attenuation characteristics, This represents the peak-to-peak value of the received ultrasonic signal. This is the reference peak value for clear water. It is the natural logarithm function.

[0069] In a specific embodiment of the present invention, the pre-stored sediment parameter inversion mapping and acousto-optic fusion calculation parameters include a sediment particle size inversion mapping function, an optical concentration reference mapping function, an acoustic concentration reference mapping function, and a weighting function; the specific acquisition process is as follows: The river sediment concentration and particle size measurement device was placed in an experimental water tank with known sediment concentration and particle size distribution. The water temperature in the experimental water tank was kept stable at 20±2℃, and the water flow velocity was ≤1 m / s to avoid environmental interference. Three types of standard sediment samples were used, with particle size ranges of 0.02-0.125 mm, 0.125-0.2 mm, and 0.2-0.5 mm, respectively. The concentration gradient increased in increments of 0.5 g / L, covering the range of 0-10 g / L. For each concentration-particle size combination, 30 sets of valid signals were collected, and a total of 950 sets of calibration data were obtained. Three sets of sediment samples with particle size ranges of 0.02-0.125 mm, 0.125-0.2 mm, and 0.2-0.5 mm were configured in the water tank, and the sediment concentration range covered the range of 0-10 g / L.

[0070] The device synchronously collects the voltage values ​​of 90° scattered light signals under different concentration-particle size combinations. 135° scattered light signal voltage value and ultrasonic receiving signals That is, the ultrasonic attenuation signal, and a total of 950 sets of valid data were acquired to form a calibration dataset.

[0071] Calculate normalized difference features based on the calibrated dataset:

[0072] And construct the optical feature intensity by weighting:

[0073] in and These are the fixed weight coefficients obtained through calibration and fitting.

[0074] At the same time, the ultrasonic attenuation signal Calculate the peak value of ultrasound And construct acoustic attenuation characteristics:

[0075] Establish sediment particle size inversion mapping functions respectively:

[0076] Acoustic concentration reference mapping function:

[0077] And the optical concentration reference mapping function:

[0078] And establish a weight function Used for mixing sediment concentrations.

[0079] To facilitate real-time computation on the FPGA, the aforementioned pre-stored sediment parameter inversion mapping and acousto-optic fusion calculation parameters are implemented using a piecewise linear model combined with a lookup table (LUT). The voltage values ​​of the 90° scattered light signals from the two scattered light signals are extracted within each time window. Voltage value of scattered light signal at 135° Unit: V, normal operating range is approximately 0.8V to 3V, and normalized differential features are constructed:

[0080] in, This is a protective measure to prevent numerical divergence caused by the denominator approaching zero under conditions such as momentary shading, wire breakage, or abnormal operating conditions. Because... 1+ 2. Under normal operating conditions, it is much greater than The impact of this protection item on the eigenvalue calculation is negligible.

[0081] Simultaneously weighted construction of optical feature intensity:

[0082] in , To calibrate the fixed weight coefficients obtained from the fitting, the least mean square error criterion was used to determine the following: =0.54, =0.46. The acoustic channel uses the peak-to-peak value of ultrasound under clear water conditions as a reference, and sets the clear water reference peak-to-peak value as 0.46. ref =2.000V, for the actual measured peak-to-peak value of the ultrasound. Constructing acoustic attenuation characteristics:

[0083] To facilitate real-time hardware implementation, the acoustic concentration inversion mapping function , ( ), Optical Concentration Reference Mapping Function , ( ) and weight function All ( ) are represented in the form of a piecewise linear model, and their segment thresholds and linear coefficients are pre-stored in the FPGA's on-chip read-only memory using a lookup table. During runtime, the FPGA first performs interval discrimination based on the input feature values ​​to determine the segment number, and then reads the slope coefficient and intercept coefficient of the corresponding segment to perform multiplication and addition operations to obtain the result. and And calculate based on the weighting function Post-output fusion concentration A boundary saturation strategy is employed for inputs exceeding the calibration range to ensure stable and reliable output.

[0084] In a specific embodiment of the present invention, an acoustic concentration inversion mapping function is constructed. Acoustic concentration estimate Unit: g / L, from It is obtained through piecewise linear function inversion. Let the piecewise threshold be:

[0085] when When falling into different intervals, the corresponding linear coefficients are used for calculation:

[0086] And perform saturation processing on out-of-bounds inputs: when Time to take ;when Time to take .

[0087] In a specific embodiment of the present invention, an optical concentration reference mapping function is constructed. Optical Concentration Reference Value Unit: g / L, from Obtained through piecewise linear functions; due to The dimension of the value is voltage, and its range is consistent with the scattered light voltage, so a mapping is directly established in the voltage domain. Let the segmented threshold be defined, in V.

[0088] when When falling into different intervals, the corresponding linear coefficients are used for calculation:

[0089] And perform saturation processing on out-of-bounds inputs: when Time to take ;when Time to take .

[0090] In a specific embodiment of the present invention, a weighting function is constructed and the concentration is fused: the final sediment concentration is obtained by acoustic-optical weighted fusion.

[0091] in, ∈[0,1] represents the acoustic weights. To achieve biased optical estimation in the low-concentration range and biased acoustic estimation in the high-concentration range, and to avoid output jitter caused by weight jumps, a piecewise linear weighting function is adopted. As a criterion, let:

[0092] definition:

[0093] This yields the fusion concentration. .

[0094] In a specific embodiment of the present invention, the segmented threshold and linear coefficients of the above-mentioned mapping function are stored in the on-chip ROM of the FPGA in the form of a lookup table. During runtime, the FPGA performs interval discrimination on the input features to obtain the segment number, reads the slope and intercept coefficient of the corresponding segment, and completes a multiplication-addition operation to obtain the result. and Then calculate based on the weighting function. Output fusion concentration A boundary saturation strategy is employed for inputs exceeding the calibration range to ensure stable and reliable output.

[0095] The result , , and weight function The parameters for sediment parameter inversion mapping and acousto-optic fusion calculation are pre-stored in the on-chip memory of the FPGA development board in the form of lookup tables, piecewise linear models and their coefficients.

[0096] This invention integrates the lookup table, piecewise linear model, and weighting function required for acoustic-optical fusion inversion into FPGA hardware, enabling on-site synchronous acquisition, real-time fusion, and high-precision inversion of acoustic-optical dual-modal signals. Furthermore, this invention utilizes dual-angle optical scattering signals to enhance particle size resolution, leverages ultrasonic attenuation signals to broaden the concentration measurement range, and employs decision-level weighted fusion to balance accuracy and stability across different concentration ranges. This provides a complete solution for integrated, real-time online monitoring of river sediment concentration and particle size parameters.

[0097] Example 3 This invention provides an acoustic-optical fusion device and method for measuring river sediment concentration and particle size. Based on Examples 1 and 2, it is used to detect the sediment particle size and sediment concentration of a river to be tested, specifically including: Device assembly and circuit setup: Assemble the laser (YSD85-121) and two photodiodes (BPX61) on the optical support, and carefully calibrate their spatial positions to ensure that the laser emission direction forms precise angles of 90° and 135° with the receiving directions of the two photodiodes (with deviations controlled within ±1°). Use a level to ensure that all three are on the same horizontal plane.

[0098] The ultrasonic transmitting probe (DYW-1M-01T) and the ultrasonic receiving probe (DYW-01-01E) were respectively fixed on the two platform plates of the ultrasonic probe holder, with the probe spacing set at 50mm. To improve stability in the field, PTFE tape was used to reinforce the contact area between the probe and the holder.

[0099] Connect the GPIO port on the FPGA development board (EP4CE10F17C8) to the laser driver module using DuPont wires; connect the outputs of the two photodiodes to the inputs of two independent amplifier modules (AD825), and then the amplified signals are fed into the active filter module (UAF42) and finally into the analog-to-digital converter module (AD9248). The analog-to-digital converter module is connected to the FPGA development board via a 22-pin header.

[0100] Use SMA adapter cables to solder the positive and negative terminals of the ultrasonic transmitting and receiving probes, respectively. Connect the transmitting SMA cable to the output port of the digital-to-analog converter chip (AD9708), and the receiving SMA cable to the input port of the analog-to-digital converter chip (AD9280). The AD9708 and AD9280 together form a digital-to-analog-to-digital converter module, which is connected to the FPGA development board via pin headers.

[0101] Connect the LCD screen (F043A11-601) to the FPGA development board via the RGB parallel interface, and connect the two power modules. After verifying that all connections are correct, close the switch.

[0102] Experimental testing of the river to be tested: Place the device in the river to be tested, fix the optical bracket 21 and the ultrasonic probe bracket 12, and ensure that the photodiode 16 is installed at an angle of 90° and 135° with an angle deviation within ±1°, and that the ultrasonic transmitting probe 23 and the ultrasonic receiving probe 13 are in stable positions.

[0103] Turn on switch 10 of FPGA development board 22 and connect to power supply through power interface 9. The two power modules 2 supply power to the corresponding units respectively, and the device is powered on and initialized.

[0104] The FPGA development board 22 outputs a 1 kHz square wave modulation signal through GPIO port 5 to drive the laser driver module 17 to work. The laser 18 emits a laser to irradiate the sediment and water body of the river to be tested. Two photodiodes 16 collect the scattered light signals in the 90° and 135° directions respectively. After the signals are amplified by the amplifier circuit module 12 and filtered by the active filter module 1, they are sent to the analog-to-digital conversion module 11 to be converted into digital dual-angle optical scattering signals, which are then transmitted to the FPGA development board 22 through the pin header 8.

[0105] The FPGA development board 22 controls the digital-to-analog-to-digital converter module 16 to perform digital-to-analog conversion and outputs a 1MHz excitation signal to drive the ultrasonic transmitting probe 23 to emit ultrasonic waves. The ultrasonic waves propagate and attenuate in the sediment-laden water body. The ultrasonic receiving probe 13 receives the attenuated ultrasonic signal, which is then converted from analog to digital by the digital-to-analog-to-digital converter module 16 and transmitted to the FPGA development board 22.

[0106] The FPGA development board 22 performs split-path specialization processing on the received dual-angle optical scattering signal and ultrasonic signal, and then performs decision-level weighted fusion to output the sediment concentration C and sediment particle size D. The calculation process is as follows: Depend on , Constructing normalized difference features:

[0107] The sediment particle size is obtained by using a pre-stored sediment particle size inversion mapping function:

[0108] The acoustic concentration estimate is obtained by inversion using a pre-stored acoustic concentration reference mapping function. The acoustic concentration estimate is first constructed from the ultrasonic peak-to-peak values ​​to obtain acoustic attenuation characteristics.

[0109] in ref=2.000V is the reference peak value for clear water, and ln() is the natural logarithm function. Subsequently, a piecewise linear lookup table is used to achieve acoustic concentration inversion: FPGA... Perform interval discrimination, read the slope coefficient and intercept coefficient of the corresponding segment, and complete a multiplication-addition operation to obtain the result. The acoustic concentration inversion mapping parameters are shown in Table 1: Table 1 Acoustic Concentration Inversion Mapping Parameters

[0110] Saturation processing is applied to out-of-bounds inputs: when Time to take ,when Time to take .

[0111]

[0112] And by using a pre-stored optical density reference mapping function, the optical density reference value is obtained:

[0113] The optical characteristic intensity is constructed by weighting the voltage characteristics of the two scattered light sources:

[0114] Among them, the weighting coefficient =0.54, =0.46. Subsequently, a piecewise linear lookup table was used to achieve optical concentration inversion: FPGA for... Perform interval discrimination, read the slope coefficient and intercept coefficient of the corresponding segment, and complete a multiplication-addition operation to obtain the result. The optical concentration inversion mapping parameters are shown in Table 2. Table 2 Optical Concentration Inversion Mapping Parameters

[0115] Saturation processing is applied to out-of-bounds inputs: when Time to take ,when Time to take .

[0116]

[0117] According to the preset weight function Calculate fusion weights The final sediment concentration was obtained by using a sound-optic weighted fusion method.

[0118] in, For acoustic weighting. To balance optical sensitivity in the low concentration range with acoustic stability in the high concentration range, A piecewise linear function varying with concentration range is used, and... As a criterion, the parameters of the weighting function are shown in Table 3: Table 3 Weighting function parameters

[0119] The weighting function is defined as: when hour ;when hour exist Linear transition within the interval; when hour FPGA based on Perform interval discrimination and complete one linear calculation to obtain This leads to the output of fusion concentration. .

[0120] The FPGA development board 22 transmits the inverted sediment concentration and sediment particle size data to the LCD screen 6 through the connection interface 7, realizing the real-time display of the measurement results.

[0121] Record the data displayed directly on the LCD screen and label it as the predicted sediment concentration value. Predicted values ​​of sediment particle size Simultaneously, the true values ​​of sediment concentration in the river under test were measured using both the drying method and the sieve calibration method. True value of median particle size of sediment The sediment concentration and particle size verification data are shown in Table 4. Table 4

[0122] As shown in the table above, the acoustic-optical fusion measurement device provided by this invention has a maximum relative error of 8.00% for concentration measurement and a maximum relative error of 9.24% for median particle size measurement within a wide concentration range (0.5-7.5 g / L) and particle size range (0.02-0.5 mm).

[0123] To further highlight the technical advantages of the acoustic-optical fusion scheme of this invention, parallel control experiments were conducted simultaneously using a single optical method and a single acoustic method under the same environmental conditions and with the same gravel sample. The measurement results of the single ultrasonic attenuation method are shown in Table 5, and the measurement results of the single light scattering method are shown in Table 6. Table 5

[0124] Table 6

[0125] Comparative experimental data shows that the single ultrasonic attenuation method has a large error in the low concentration range, while the single light scattering method has a large error due to insufficient penetration in the high concentration range. This invention, by fusing dual-angle optical signals and ultrasonic signals, combined with the nonlinear fitting capability of the acoustic-optical fusion inversion algorithm, expands the measurement range of sediment concentration and particle size and improves measurement accuracy. Furthermore, for experiments in different scenarios, in the still water area of ​​a reservoir (low flow velocity, low concentration), the concentration measurement error of this invention is ≤10%, which is superior to the single ultrasonic method (error ≤20%) and the single optical method (error ≤30%). In the estuary area (high flow velocity, high concentration), this invention can still stably output measurement results, while the single optical method frequently experiences data saturation due to insufficient light penetration, and the single ultrasonic method has an error exceeding 15% due to flow velocity interference, fully demonstrating the complex environment adaptability advantage of this invention. Simultaneously, the real-time inversion implemented by the embedded FPGA enables real-time monitoring in the field, overcoming the latency problem of traditional machine learning solutions that rely on cloud computing. This device provides a reliable solution for integrated, high-precision, real-time online monitoring of river sediment concentration and particle size distribution.

Claims

1. A sound-optical fusion device for measuring river sediment concentration and particle size, characterized in that, It includes an optical unit, an acoustic unit, an FPGA processing unit connected to the optical unit and the acoustic unit respectively, a display unit connected to the FPGA processing unit, and a power supply unit, wherein the power supply unit is connected to the optical unit and the FPGA processing unit respectively; The optical unit includes an analog-to-digital converter module (11), a first active filter module (1), a second active filter module (2), a first amplifier circuit module (14), a second amplifier circuit module (15), a laser driver module (17), a laser (18), a first photodiode (19), a second photodiode (20), and an optical support (21). The analog-to-digital converter module (11) is connected to the first active filter module (1) and the second active filter module (2) respectively. The first active filter module (1) is connected to the first amplifier circuit module (14) and the first photodiode (19) in sequence. The second active filter module (2) is connected to the second amplifier circuit module (20) in sequence. The laser drive module (17) is connected to the laser (18), the first photodiode (19) is positioned at a 90° angle to the light emission direction of the laser (18), and the second photodiode (20) is positioned at a 135° angle to the light emission direction of the laser (18); the laser drive module (17) is connected to the power supply unit; the laser (18), the first photodiode (19), and the second photodiode (20) are all mounted on the optical bracket (21); the analog-to-digital conversion module (11) and the laser drive module (17) are both connected to the FPGA processing unit; The acoustic unit includes an ultrasonic probe bracket (12), a digital-to-analog (D / A) converter module (16), an ultrasonic receiving probe (13), and an ultrasonic transmitting probe (23); the D / A converter module (16) is connected to the ultrasonic transmitting probe (23) and the ultrasonic receiving probe (13) respectively, and the ultrasonic transmitting probe (23) and the ultrasonic receiving probe (13) are both mounted on the ultrasonic probe bracket (12); the D / A converter module (16) is connected to the FPGA processing unit; The FPGA processing unit includes an FPGA development board (22) and GPIO ports (5), headers (8), a power interface (9), and a switch (10) disposed thereon. The FPGA development board (22) is connected to the analog-to-digital conversion module (11) via headers (8), and the FPGA development board (22) is connected to the laser driver module (17) via GPIO ports (5). The FPGA development board (22) is connected to the display unit and the power supply unit. The display unit includes an LCD screen (6), which is connected to the FPGA development board (22) via a connection interface (7); The power supply unit includes a first power supply module (3) and a second power supply module (4). The first power supply module (3) is connected to the FPGA development board (22), the first active filter module (1) and the second active filter module (2) respectively. The second power supply module (4) is connected to the first amplifier circuit module (14), the second amplifier circuit module (15) and the laser driver module (17) respectively.

2. The acoustic-optical fusion river sediment concentration and particle size measurement device according to claim 1, characterized in that, In the optical unit, the first photodiode (19) and the second photodiode (20) respectively acquire 90° simulated scattered light signal and 135° simulated scattered light signal; The first amplifier circuit module (14) and the first active filter module (1) amplify and filter the 90° analog scattered light signal and transmit it to the analog-to-digital conversion module (11) for analog-to-digital conversion to obtain the 90° digital scattered light signal; The second amplifier circuit module (15) and the second active filter module (2) amplify and filter the 135° analog scattered light signal and transmit it to the analog-to-digital conversion module (11) for analog-to-digital conversion to obtain the 135° digital scattered light signal; The analog-to-digital conversion module (11) transmits the 90° digital scattered light signal and the 135° digital scattered light signal to the FPGA development board (22). The laser driver module (17) receives the modulation signal output by the FPGA development board (22) and drives the laser (18) to emit laser light according to the modulation signal.

3. The acoustic-optical fusion river sediment concentration and particle size measurement device according to claim 2, characterized in that, In the acoustic unit, the digital-to-analog-to-digital converter module (16) outputs an analog excitation signal under the control of the FPGA development board (22) to drive the ultrasonic transmitting probe (23) to emit ultrasonic waves. The ultrasonic receiving probe (13) receives the ultrasonic waves after they have been attenuated by the water and converts them into ultrasonic analog signals. The digital-to-analog-to-digital converter module (16) performs analog-to-digital conversion on the ultrasonic analog signals to obtain ultrasonic digital signals, which are then transmitted to the FPGA development board (22).

4. The acoustic-optical fusion river sediment concentration and particle size measurement device according to claim 3, characterized in that, The workflow of the FPGA processing unit includes: It can receive 90° digital scattered light signals, 135° digital scattered light signals, and ultrasonic receiving signals; Normalized differential processing was performed on the 90° digital scattered light signal and the 135° digital scattered light signal, and particle size sensitive features were extracted. Combined with the pre-stored sediment particle size inversion mapping in the FPGA development board (22), the sediment particle size was obtained. The attenuation characteristics of the ultrasonic received signal are extracted and combined with the acoustic concentration inversion mapping pre-stored in the FPGA development board (22) to obtain the acoustic concentration. Based on the intensity information of the 90° digital scattered light signal and the 135° digital scattered light signal, combined with the optical concentration reference mapping pre-stored in the FPGA development board (22), the optical concentration reference value is obtained; The acoustic concentration and optical concentration reference values ​​are weighted and fused according to the weighting function stored in the FPGA development board (22) to output the sediment concentration.

5. A method for measuring river sediment concentration and particle size based on the acoustic-optical fusion of the device described in any one of claims 1-4, characterized in that, include: The river sediment concentration and particle size measuring device is placed in the water body to be measured and powered by the power supply unit to complete the device initialization. A 1 kHz square wave modulation signal is output through the FPGA development board to drive the laser to emit laser light. Based on the laser emitted by the laser, the two photodiodes of the optical unit collect the 90° analog scattered light signal and the 135° analog scattered light signal respectively, and then amplify, filter and convert the signal to digital to obtain the 90° digital scattered light signal and the 135° digital scattered light signal. The analog-to-digital converter module is controlled by an FPGA development board to output an analog excitation signal, which drives the ultrasonic transmitting probe to emit ultrasonic waves into the water body to be tested. The ultrasonic receiving probe then acquires the ultrasonic waves after they have been attenuated by the water body to obtain the ultrasonic receiving signal. Based on the 90° digital scattered light signal, the 135° digital scattered light signal, and the ultrasonic received signal, the FPGA development board performs split processing and weighted fusion based on the pre-stored sediment parameter inversion mapping and acousto-optic fusion calculation parameters to obtain the sediment concentration and sediment particle size.

6. The method for measuring river sediment concentration and particle size using acoustic-optical fusion according to claim 5, characterized in that, The determination of sediment concentration and sediment particle size specifically includes: Based on the 90° and 135° digital scattered light signals, normalized differential features are constructed, and sediment particle size inversion mapping is performed to obtain the sediment particle size. Based on the 90° and 135° digital scattered light signals, the optical characteristic intensity is constructed by weighting and optical concentration reference mapping is performed to obtain the optical concentration reference value. Based on the peak-to-peak value of the received ultrasonic signal, acoustic attenuation characteristics are constructed, and acoustic concentration inversion mapping is performed to obtain an estimated acoustic concentration value. The sediment concentration is obtained by weighted fusion calculation based on the optical concentration reference value and the acoustic concentration estimate.

7. The method for measuring river sediment concentration and particle size using acoustic-optical fusion according to claim 6, characterized in that, The expression for the particle size of the sediment is as follows: in, The particle size of the sediment This is the sediment particle size inversion mapping function. For normalized difference features, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. This is a preset minimum constant.

8. The method for measuring river sediment concentration and particle size using acoustic-optical fusion according to claim 6, characterized in that, The expression for the sediment concentration is as follows: in, The concentration of sediment. As weight, For acoustic concentration estimation, This is an optical concentration reference value. For optical concentration reference mapping function, For optical characteristic intensity, This is a 90° digital scattered light signal. This is a 135° digital scattered light signal. and These are the weighting coefficients for optical characteristics. This is the acoustic concentration inversion mapping function. Acoustic attenuation characteristics, This represents the peak-to-peak value of the received ultrasonic signal. This is the reference peak value for clear water. It is the natural logarithm function.

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