Distributed sediment measurement method and system

Abstract

The invention relates to the technical field of sediment monitoring, in particular to a distributed sediment measurement method and system, and the method comprises the following steps: carrying out the automatic frequency modulation through employing an NLMS algorithm, transmitting detection waves at different ultrasonic frequencies, obtaining an ultrasonic image and ultrasonic receiving intensity at each depth of a target position, averaging the ultrasonic receiving intensity, and obtaining an average value; the method comprises the following steps: obtaining ultrasonic receiving average intensity under each depth, obtaining sediment weight under each depth of a target position based on a quotient between the ultrasonic receiving average intensity and the ultrasonic receiving intensity under purified water, and determining sediment density under each depth of the target position based on the sediment weight and gravitational acceleration. And determining the sediment distribution of the river channel according to the sediment density at each depth and the corresponding ultrasonic imaging graph. When the sediment content distribution at different depths is measured, the problem of scattering attenuation in propagation can be effectively solved by changing the ultrasonic frequency, and the echo receiving sensitivity, the measurement precision and the adaptability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sediment monitoring, and in particular to a distributed sediment measurement method and system. Background Art

[0002] my country is rich in river resources, which has promoted the rapid development of agricultural irrigation, water conservancy projects and environmental engineering. However, many river areas currently carry a large amount of sediment. River basins with high sediment content will not only affect the development of social economy, but the continuous accumulation of sediment will also make the riverbed wider and the water level rise, endangering people's lives and safety; in addition, for water conservancy projects, the operation of hydraulic units under sandy water will seriously wear the unit wall, reducing its service life, which seriously restricts the development of green energy. Therefore, if sediment information can be monitored in real time, it will provide great engineering practical significance for environmental protection, estuary rivers and related projects, and the sustainable development of water resources.

[0003] The existing sediment monitoring methods mainly include direct measurement, vibration, radiation, ultrasonic measurement, capacitance and photoelectric methods. Among them, the ultrasonic method is the most commonly used because of its non-contact measurement method and the ability to avoid the problems of surface obstruction and regular cleaning of objects in radiation and photoelectric methods, providing higher measurement accuracy. However, the ultrasonic method has its own absorption and attenuation characteristics, which leads to the fact that the echo reception in areas with high sediment content is greatly affected by distance, making it difficult to accurately measure the sediment distribution in areas with high sediment content.

[0004] Based on this, how to achieve accurate measurement of sediment distribution in areas with high sediment content is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a distributed sediment measurement method and system, which takes automatic frequency modulation as the core. When measuring the distribution of sediment content at different depths, by changing the ultrasonic frequency, the scattering attenuation problem in propagation can be effectively reduced, and the echoes that can be received at the ultrasonic receiver are increased. The sensitivity, measurement accuracy and adaptability of echo reception are improved to solve the technical problem of how to achieve accurate measurement of sediment distribution in areas with high sediment content.

[0006] The present invention is implemented by the following technical scheme: A distributed sediment measurement method comprises the following steps: The NLMS algorithm is used to automatically adjust the frequency of the ultrasonic transmitter, and the detection wave is transmitted to the target position at different ultrasonic frequencies to obtain the ultrasonic imaging diagram and ultrasonic receiving intensity at each depth of the target position; The ultrasonic receiving intensity at the same depth of the target position is averaged to obtain the average ultrasonic receiving intensity at each depth; Based on the quotient between the average ultrasonic receiving intensity and the ultrasonic receiving intensity under clean water, the sediment weight at each depth of the target position is obtained, and based on the calculation formula of the sediment weight and gravity acceleration, Mode , and obtain the sediment density at each depth of the target location, where Indicates the weight of sediment. represents the acceleration due to gravity; The sediment distribution in the river channel is determined based on the sediment density at each depth of the target location and the corresponding ultrasonic imaging map.

[0007] According to a preferred embodiment, an ultrasonic transmitter is used to continuously transmit at different angles at different depths.

[0008] According to a preferred embodiment, ultrasonic transmitters arranged at different depths are used to transmit detection waves at different angles.

[0009] According to a preferred embodiment, the ultrasonic transmitters arranged at different depths are used to transmit detection waves perpendicular to the flow of river water. The ultrasonic transmitters at different depths transmit detection waves at optimal frequencies respectively. The optimal frequency is the transmission frequency corresponding to the ultrasonic frequency iteration at the depth position when the convergence condition is met. The convergence condition is that the rate of change of the receiving intensity before and after the ultrasonic frequency iteration tends to be stable.

[0010] According to a preferred embodiment, the calculation expression of the receiving intensity change rate before and after the ultrasonic frequency iteration is as follows:

[0011] In the above formula, represents the rate of change, Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the time difference between the ultrasonic transmitter transmitting and the ultrasonic receiver receiving.

[0012] According to a preferred embodiment, the automatic frequency modulation to transmit detection waves to the target position at different ultrasonic frequencies specifically includes: Using a first ultrasonic transmitter to transmit a detection wave to a target position at a first depth, using a first ultrasonic receiver to receive a first echo at the first depth, and obtaining a first ultrasonic imaging image of the target position at the first depth based on the first echo; A second ultrasonic transmitter is used to transmit a detection wave to a target position at a second depth, a second ultrasonic receiver is used to receive a second echo at the second depth, and a second ultrasonic imaging diagram of the target position at the second depth is obtained based on the second echo.

[0013] The present invention also provides a distributed sediment measurement system, which is applied to the distributed sediment measurement method as described above, and the system comprises: The ultrasonic transceiver module is used to automatically adjust the frequency of the ultrasonic transmitter using the NLMS algorithm, transmit detection waves to the target position at different ultrasonic frequencies, and obtain ultrasonic imaging images and ultrasonic receiving intensity at various depths of the target position; The first processing module is used to average the ultrasonic receiving intensity at the same depth of the target position to obtain the average ultrasonic receiving intensity at each depth; The second processing module is used to obtain the sediment weight at each depth of the target position based on the quotient between the average ultrasonic receiving intensity and the ultrasonic receiving intensity under clean water, and to calculate the sediment weight and gravity acceleration based on the calculation formula Mode , and obtain the sediment density at each depth of the target location, where Indicates the weight of sediment. represents the acceleration due to gravity; The third processing module is used to determine the sediment distribution in the river channel according to the sediment density at each depth of the target position and the corresponding ultrasonic imaging image.

[0014] According to a preferred embodiment, the first ultrasonic transmitter, the second ultrasonic transmitter, the first ultrasonic receiver and the second ultrasonic receiver are built into the same U-shaped tube, the first ultrasonic transmitter and the second ultrasonic transmitter are arranged on the first side of the U-shaped tube, the first ultrasonic receiver and the second ultrasonic receiver are arranged on the second side of the U-shaped tube, and the U-shaped tube is configured to have an adjustable opening direction.

[0015] According to a preferred embodiment, the system also includes a system power module, an ultrasonic power module, an ultrasonic signal generating circuit, an ultrasonic signal receiving circuit, a storage module and a CPU. The ultrasonic power module is electrically connected to the ultrasonic signal generating circuit, the ultrasonic signal receiving circuit and the system power module, respectively. The ultrasonic signal receiving circuit is wirelessly connected to the CPU, and the CPU is electrically connected to the storage module.

[0016] According to a preferred embodiment, the system power module is electrically connected to a solar power generation device.

[0017] The technical solution of a distributed sediment measurement method and system provided by the present invention has at least the following advantages and beneficial effects: (1) When measuring the distribution of sediment content at different depths, the present invention can effectively reduce the scattering attenuation problem in propagation by changing the ultrasonic frequency, increase the echo that can be received at the ultrasonic receiver, and improve the sensitivity, measurement accuracy and adaptability of echo reception; (2) By selecting ultrasonic waves as the method for measuring sediment, the emitted sound wave energy can prevent sediment from accumulating on the surface of the ultrasonic transmitter and the ultrasonic receiver, thereby ensuring the accuracy of measurement; (3) By installing the ultrasonic transmitter and the ultrasonic receiver in a U-shaped tube, it can prevent damage caused by collision with aquatic organisms or other hard objects, and effectively protect the safety of the ultrasonic transmitter, the ultrasonic receiver and related lines; (4) The use of solar power generation equipment for power supply enables the system to operate outdoors for a long time; (5) By adjusting the angle of the U-shaped tube to change the ultrasonic transmission and reception angle, the sediment situation can be better monitored; (6) The use of wireless transmission mode does not require additional cable transmission, which can further reduce the failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a flow chart of a distributed sediment measurement method provided in Example 1 of the present invention; Figure 2 A schematic diagram of the structure of a U-shaped tube provided in Example 2 of the present invention; Figure 3 A schematic diagram of the layout of a river flow measurement system provided in Example 2 of the present invention; Reference numerals: 1 - U-shaped tube, 2 - first ultrasonic transmitter, 3 - second ultrasonic transmitter, 4 - first ultrasonic receiver, 5 - second ultrasonic receiver. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Example 1 Figure 1 This is a flow chart of the distributed sediment measurement method provided by an embodiment of the present invention. Figure 1 As shown in the figure, the distributed sediment measurement method can be roughly divided into three steps, as follows: Step 1: Use the NLMS algorithm to automatically adjust the frequency of the ultrasonic transmitter, transmit detection waves to the target position at different ultrasonic frequencies, and obtain ultrasonic imaging images and ultrasonic receiving intensity at various depths of the target position.

[0021] Specifically, in one implementation of this embodiment, an ultrasonic transmitter is used to continuously transmit at different angles at different depths. By adjusting the transmission position and transmission angle of the ultrasonic transmitter, a wider target position can be covered, the detection range can be expanded, and the sediment situation can be better monitored. In addition, by selecting ultrasound as a method for measuring sediment, the emitted sound wave energy can prevent sediment from accumulating on the surface of the ultrasonic transmitter and the ultrasonic receiver, thereby ensuring the accuracy of the measurement.

[0022] In one embodiment, a pair of ultrasonic transmitters and ultrasonic receivers may be configured, and the ultrasonic transmitters and ultrasonic receivers may be displaced by a related displacement mechanism, thereby changing the emission position of the ultrasonic wave; the displacement mechanism may be a slide rail provided to carry the ultrasonic transmitter and ultrasonic receiver, and the displacement may be achieved by electrically driving a slider connected to the ultrasonic transmitter and ultrasonic receiver to move along the slide rail, etc., and no specific restrictions are made here; in one embodiment, the sound wave transmitter and ultrasonic receiver may be driven to adjust the emission angle by an angle adjustment structure; the angle adjustment mechanism may be a rotating disk provided between the slider and the ultrasonic transmitter / ultrasonic receiver, and the angle adjustment may be achieved by electrically driving the rotating disk to rotate along the slider, etc., and no specific restrictions are made here.

[0023] Specifically in this embodiment, a plurality of pairs of ultrasonic transmitters and ultrasonic receivers are arranged, and the plurality of pairs of ultrasonic transmitters and ultrasonic receivers are arranged at different depths at intervals. The ultrasonic transmitters arranged at different depths are used to transmit detection waves at different angles. The angle adjustment can be carried out by the rotating disk rotation method provided above, which will not be elaborated here. Among them, the number of ultrasonic transmitters and ultrasonic receivers to be arranged is determined according to the actual target river channel depth, and there is no specific restriction. For example, two pairs can be set, or more than two pairs can be set. The following description will be taken as an example of two pairs of ultrasonic transmitters and ultrasonic receivers.

[0024] Furthermore, the ultrasonic transmitters arranged at different depths transmit detection waves perpendicular to the flow direction of the river channel. The ultrasonic transmitters at different depths transmit detection waves at the optimal frequency. The optimal frequency is the transmission frequency corresponding to the ultrasonic frequency iteration at the depth position when the NLMS algorithm is used for automatic frequency modulation of the ultrasonic transmitter, and the convergence condition is that the rate of change of the receiving intensity before and after the ultrasonic frequency iteration tends to be stable; specifically, as the transmission frequency gradually increases from the initial frequency, the rate of change of the receiving intensity gradually converges, and it is considered that the transmission frequency is the optimal frequency for sediment distribution detection at the depth, that is, the transmission frequency matches the sediment particle size at the depth. The calculation expression of the rate of change of the receiving intensity before and after the ultrasonic frequency iteration is as follows:

[0025] In the above formula, represents the rate of change, Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the time difference between the ultrasonic transmitter transmitting and the ultrasonic receiver receiving.

[0026] It should be noted that, in this embodiment, when the NLMS algorithm is used to perform automatic frequency modulation of the ultrasonic transmitter, the initial ultrasonic frequency is set to 1.25 MHz for frequency modulation, the step size is 200 KHz and varies with the number of iterations, and the maximum transmission frequency is set to 2 MHz as a constraint to make it converge faster. The NLMS algorithm is not described in detail here.

[0027] When measuring the distribution of sediment content at different depths, this embodiment can effectively reduce the scattering attenuation problem in propagation by changing the ultrasonic frequency, increase the echoes that can be received at the ultrasonic receiver, and improve the sensitivity, measurement accuracy and adaptability of echo reception.

[0028] Further, regarding the automatic frequency modulation to transmit detection waves to the target position at different ultrasonic frequencies, two pairs of ultrasonic transmitters and ultrasonic receivers are used as examples for explanation, specifically including: utilizing the first ultrasonic transmitter 2 to transmit detection waves to the target position at a first depth position, receiving the first echo at the first depth position by the first ultrasonic receiver 4, and obtaining a first ultrasonic imaging diagram of the target position at the first depth based on the first echo; utilizing the second ultrasonic transmitter 3 to transmit detection waves to the target position at a second depth position, receiving the second echo at the second depth position by the second ultrasonic receiver 5, and obtaining a second ultrasonic imaging diagram of the target position at the second depth based on the second echo.

[0029] Based on the above method, the ultrasonic imaging diagram and ultrasonic receiving intensity at different depths of the target position can be obtained, and the sediment density at different depths can be determined by further processing the ultrasonic receiving intensity.

[0030] Step 2: average the ultrasonic receiving intensity at the same depth of the target position to obtain the average ultrasonic receiving intensity at each depth; based on the quotient between the ultrasonic receiving average intensity and the ultrasonic receiving intensity under clean water, obtain the sediment density at each depth of the target position, expressed as , is the average intensity of ultrasonic wave received underwater in sandy water, It is the ultrasonic receiving intensity under clean water.

[0031] Further, based on the sediment weight and the acceleration due to gravity Calculation of Mode , and obtain the sediment density at each depth of the target location, where the gravity acceleration About 9.81 m / s².

[0032] Step 4: Determine the sediment distribution in the river channel based on the sediment density at each depth of the target location and the corresponding ultrasonic imaging map.

[0033] It should be noted that there is a correlation between ultrasonic frequency and different sediment particle sizes. The different shapes and sizes of sediment will lead to different sedimentation velocities, so they will show different distributions at different depths. The sediment particle size distribution at the corresponding depth can be determined based on the ultrasonic imaging. According to the sediment particle size distribution and combined with the sediment density calculated above, the distribution of sediment at different depths can be determined.

[0034] Example 2 This embodiment provides a distributed sediment measurement system based on the technical solution provided in Embodiment 1. The distributed sediment measurement system is applied to the method provided in Embodiment 1.

[0035] Specifically in this embodiment, the ultrasonic distributed sediment measurement system includes an ultrasonic transceiver module, a first processing module, a second processing module and a third processing module. Among them, the ultrasonic transceiver module is used to use the NLMS algorithm to automatically adjust the frequency of the ultrasonic transmitter, transmit detection waves to the target position at different ultrasonic frequencies, and obtain ultrasonic imaging diagrams and ultrasonic receiving intensity at each depth of the target position; the first processing module is used to average the ultrasonic receiving intensity at the same depth of the target position to obtain the average ultrasonic receiving intensity at each depth; the second processing module is used to obtain the sediment density at each depth of the target position based on the intensity difference between the ultrasonic receiving average intensity and the ultrasonic receiving intensity under clean water, and based on the calculation formula of the sediment density and gravity acceleration Mode , and obtain the sediment density at each depth of the target location, where Indicates the weight of sediment. Represents gravity acceleration; the third processing module is used to determine the sediment distribution in the river channel according to the sediment density at each depth of the target position and the corresponding ultrasonic imaging map.

[0036] Further, regarding the layout design of the ultrasonic sensor, in one implementation of this embodiment, see Figure 2 As shown, the ultrasonic transmitter and the ultrasonic receiver are built into the same U-shaped tube 1 to prevent damage caused by collision with aquatic organisms or other hard objects, and effectively protect the safety of the ultrasonic transmitter, the ultrasonic receiver and related lines; further, the ultrasonic transmitters are respectively arranged on the left and right sides of the U-shaped tube 1, and the U-shaped tube 1 is configured to have an adjustable opening direction to change the ultrasonic wave receiving and transmitting angle, so as to better monitor the sediment situation.

[0037] In addition, the system also includes a solar power generation device, a system power module, an ultrasonic power module, an ultrasonic signal generating circuit, an ultrasonic signal receiving circuit, a storage module and a CPU. The system power module is electrically connected to the solar power generation device and is powered by the solar power generation device, so that the system can operate outdoors for a long time. The ultrasonic power supply module is electrically connected to the ultrasonic signal generating circuit, the ultrasonic signal receiving circuit and the system power supply module respectively, and the relevant circuits are powered by the system power supply module; the ultrasonic signal receiving circuit is wirelessly connected to the CPU, and the CPU is electrically connected to the storage module. This embodiment adopts wireless transmission, and does not require additional cable transmission, which can further reduce the failure rate.

[0038] In addition to using ultrasound to measure sediment distribution, this embodiment also provides a system for measuring river flow using ultrasonic sensors arranged upstream and downstream of the river, as follows: See also Figure 3As shown, the ultrasonic sensors arranged upstream and downstream of the river are denoted as sensor A and sensor B. Sensor A is arranged upstream, and sensor B is arranged downstream. The straight-line distance between sensors A and B is , the river flow velocity is , the angle between the line between sensor A and sensor B and the direction of river flow is , the propagation speed of ultrasound in clean water is .

[0039] Based on the above configuration, sensor A and sensor B transmit / receive alternately, where sensor A transmits, and It arrives at sensor B after a certain time, and the propagation speed is , propagation time ; Sensor B transmits, passing Arrives at sensor A after a certain time, propagation time ; From this we can get the propagation time difference as , can be ignored in calculation , from which the flow of sandy water can be calculated.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, 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 distributed sediment measurement method, characterized in that: The following steps are involved: The NLMS algorithm is used to automatically adjust the frequency of the ultrasonic transmitter, and the detection wave is transmitted to the target position at different ultrasonic frequencies to obtain the ultrasonic imaging diagram and ultrasonic receiving intensity at each depth of the target position; The ultrasonic receiving intensity at the same depth of the target position is averaged to obtain the average ultrasonic receiving intensity at each depth; Based on the quotient between the average ultrasonic receiving intensity and the ultrasonic receiving intensity under clean water, the sediment weight at each depth of the target position is obtained, and based on the calculation formula of the sediment weight and gravity acceleration, Mode , and obtain the sediment density at each depth of the target location, where Indicates the weight of sediment. represents the acceleration due to gravity; The sediment distribution in the river channel is determined based on the sediment density at each depth of the target location and the corresponding ultrasonic imaging map.

2. The distributed sediment measurement method according to claim 1, characterized in that: The ultrasonic transmitter is used to transmit continuously at different depths and angles.

3. The distributed sediment measurement method according to claim 2, characterized in that: Ultrasonic transmitters placed at different depths are used to emit detection waves at different angles.

4. The distributed sediment measurement method according to claim 3, characterized in that: The ultrasonic transmitters arranged at different depths are used to transmit detection waves perpendicular to the flow direction of the river water. The ultrasonic transmitters at different depths transmit detection waves at optimal frequencies respectively. The optimal frequency is the transmission frequency corresponding to the ultrasonic frequency iteration at the depth position when the convergence condition is met. The convergence condition is that the rate of change of the receiving intensity before and after the ultrasonic frequency iteration tends to be stable.

5. The distributed sediment measurement method according to claim 4, characterized in that: The calculation expression of the receiving intensity change rate before and after the ultrasonic frequency iteration is as follows: In the above formula, represents the rate of change, Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the ultrasonic frequency is The ultrasonic receiving intensity at Indicates the time difference between the ultrasonic transmitter transmitting and the ultrasonic receiver receiving.

6. The distributed sediment measurement method according to any one of claims 4 to 5, characterized in that: The transmitting of detection waves to the target position at different ultrasonic frequencies specifically includes: A first ultrasonic transmitter (2) is used to transmit a detection wave to a target position at a first depth, a first ultrasonic receiver (4) is used to receive a first echo at the first depth, and a first ultrasonic imaging diagram of the target position at the first depth is obtained based on the first echo; A second ultrasonic transmitter (3) is used to transmit a detection wave to a target position at a second depth, a second ultrasonic receiver (5) is used to receive a second echo at the second depth, and a second ultrasonic imaging diagram of the target position at the second depth is obtained based on the second echo.

7. A distributed sediment measurement system, characterized in that: Applied to the distributed sediment measurement method according to claim 6, the system comprises: The ultrasonic transceiver module is used to automatically adjust the frequency of the ultrasonic transmitter using the NLMS algorithm, transmit detection waves to the target position at different ultrasonic frequencies, and obtain ultrasonic imaging images and ultrasonic receiving intensity at various depths of the target position; The first processing module is used to average the ultrasonic receiving intensity at the same depth of the target position to obtain the average ultrasonic receiving intensity at each depth; The second processing module is used to obtain the sediment weight at each depth of the target position based on the quotient between the average ultrasonic receiving intensity and the ultrasonic receiving intensity under clean water, and to calculate the sediment weight and gravity acceleration based on the calculation formula Mode , and obtain the sediment density at each depth of the target location, where Indicates the weight of sediment. represents the acceleration due to gravity; The third processing module is used to determine the sediment distribution in the river channel according to the sediment density at each depth of the target position and the corresponding ultrasonic imaging image.

8. The distributed sediment measurement system according to claim 7, characterized in that: The first ultrasonic transmitter (2), the second ultrasonic transmitter (3), the first ultrasonic receiver (4) and the second ultrasonic receiver (5) are built into the same U-shaped tube (1); the first ultrasonic transmitter (2) and the second ultrasonic transmitter (3) are arranged on a first side of the U-shaped tube (1); the first ultrasonic receiver (4) and the second ultrasonic receiver (5) are arranged on a second side of the U-shaped tube (1); and the U-shaped tube (1) is configured such that the opening direction is adjustable.

9. The distributed sediment measurement system according to claim 8, characterized in that: The system also includes a system power module, an ultrasonic power module, an ultrasonic signal generating circuit, an ultrasonic signal receiving circuit, a storage module and a CPU. The ultrasonic power module is electrically connected to the ultrasonic signal generating circuit, the ultrasonic signal receiving circuit and the system power module respectively, the ultrasonic signal receiving circuit is wirelessly connected to the CPU, and the CPU is electrically connected to the storage module.

10. The distributed sediment measurement system according to claim 9, characterized in that: The system power supply module is electrically connected to the solar power generation equipment.

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