Device and method for dynamically measuring multidirectional flow of small and micro water body in plain polder area

Abstract

The invention discloses a device and a method for dynamically measuring multidirectional flow of a small and micro water body in a plain polder area. The invention relates to the technical field of hydrological monitoring. The device comprises a hollow floating annular ring; the center of the hollow floating annular ring is provided with a waterproof sealing box and a built-in motor; the waterproof sealing box horizontally sleeves the connecting rod and is connected with the cleaning module and the propeller; the waterproof sealing box is sleeved with a vertical stretching rod in the vertical direction; a control unit is fixed above the vertical stretching rod; the lower portion of the vertical stretching rod is connected with the measuring module. The control unit is used for coordinating work of all the assemblies, the nylon brush is used for cleaning suspended matter on the water surface, the propeller achieves self-adaptive propelling of the device, the vertical stretching rod meets the multi-depth measurement requirement, the measurement module obtains floating body movement information in combination with the binocular vision principle, and data can be transmitted to the cloud in real time. The whole device is simple in structure, low in maintenance cost and high in automation degree.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrological monitoring, and particularly relates to a device and method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas. Background Art

[0002] The accurate determination of the flow velocity and direction of small and micro water bodies is one of the core tasks of hydrological monitoring, and the data quality is directly related to the simulation accuracy of flood evolution, the efficiency of optimal allocation of water resources, and the reliability of water ecological health assessment. At present, the monitoring of the flow velocity and direction of small and micro water bodies mainly relies on the following two types of equipment: The first type is contact mechanical measurement equipment, represented by a rotor flowmeter, which calculates the flow velocity through the linear relationship between the rotor speed and the water flow velocity. Such equipment has a simple structure, but has disadvantages such as low single-point measurement efficiency and easy damage to the equipment; The second type is contact acoustic measurement equipment, mainly ultrasonic Doppler velocimeters (ADV), which invert the flow velocity vector through acoustic reflection signals, are easy to operate, and the data is relatively reliable, but there are still significant limitations in polder area applications. Algae attachment on the probe surface will change the acoustic transmission characteristics.

[0003] In artificially regulated river networks such as plain polder areas, the water flow of small and micro water bodies is significantly affected by the operation of sluices and pumps, showing unique hydrological and hydrodynamic characteristics of low flow velocity, multi-directionality, and strong disturbance. The presence of aquatic organisms in small and micro water bodies in polder areas will change the acoustic characteristics of the water body and interfere with signals, and will also intensify physical interference and attachment during seasonal outbreaks, reducing the measurement accuracy. In addition, traditional small and micro water body flow velocity and direction monitoring equipment also faces challenges such as low dynamic flow field analysis accuracy, high manual operation intensity, and low repeated measurement efficiency. Therefore, there is an urgent need to propose a device and method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas, which can automatically monitor the multi-directional flow of small and micro water bodies, has the ability of adaptive propulsion, multi-depth measurement, and accurate calculation of flow velocity and direction, and has a simple structure, is safe and stable, and is easy to manufacture and use.

[0005] In a first aspect, the present invention provides a device for multi-directional dynamic measurement of small and micro water bodies in plain polder areas. A vertical stretching rod is provided at the center of a hollow floating ring; a control unit, a waterproof sealing box, and a measurement module are sleeved on the vertical stretching rod; a motor is bolted to the bottom of the waterproof sealing box, and the left output shaft of the motor drives a nylon brush to reciprocate through a crank-slider mechanism composed of a crank, a connecting rod, and a slider; the right output shaft of the motor is connected to a propulsion shaft through a coupling, and the propulsion shaft drives symmetric left and right propellers to rotate to achieve the propulsion function of the device.

[0006] Further, the control unit integrates a processor, a GPS, an electronic compass, and a 4G communication module; the vertical telescopic rod realizes the lifting function through the cooperation of the guide sleeve; a counterweight plumb bob is hung on the side rear of the hollow floating ring through a rope; the solar panel is fixedly installed on the top of the vertical telescopic rod through a bracket, and the solar panel powers the motor through a solar cable.

[0007] Further, the measurement module is made of a transparent material and is connected to the vertical telescopic rod through a flange; the measurement module is provided with an electric push rod base, an electric push rod, a receiving groove, a floating body, a limiting plate, an inlet valve, and a pressure sensor; the height of the receiving groove can be the same as the height of the limiting plate and the inlet valve; the side wall of the measurement module is welded with an electric push rod base, and a telescopic electric push rod is fixedly installed on the electric push rod base through a flange. The electric push rod is equipped with a pressure sensor that can contact the floating body, and a floating body is arranged on one side of the electric push rod; the receiving groove is provided with a left camera, a right camera, and a fill light.

[0008] Further, the left camera and the right camera are connected to the control unit through camera data transmission lines; the 4G communication module in the control unit transmits the captured image data and the position information of the device to the cloud.

[0009] Further, the cable signal lines of the electric push rod, the limiting plate, the inlet valve, and the pressure sensor are led out along the inner wall of the measurement module through the electric push rod base to form an integrated cable signal line; the integrated cable signal line is placed inside the vertical telescopic rod and is respectively connected to the motor and the control unit; the motor powers each component through a multi-strand integrated cable signal line; the control unit issues instructions through the integrated cable signal line to control the motor to drive the nylon brush or the propeller and to coordinate the control of each component in the measurement module.

[0010] In a second aspect, the present invention provides a method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas, which is applied to the above-mentioned device for multi-directional dynamic measurement of small and micro water bodies in plain polder areas, including: Step 1, in the initial state, the limiting plate and the inlet valve are outside the receiving groove, and the electric push rod is in the retracted state; after the control unit issues a measurement instruction, the limiting plate and the inlet valve move into the receiving groove, and the floating body starts to move under the action of the water flow to be measured; the left camera and the right camera record the movement trajectory of the floating body and calculate the flow velocity and flow direction. Step 2, when the floating body touches the electric push rod and triggers its pressure sensor, the pressure sensor outputs a signal indicating the arrival of the floating body to the control unit; subsequently, the control unit sends an extension instruction to the electric push rod and the inlet valve, and the inlet valve extends outside the receiving groove. In Step 3, after the electric push rod extends at a constant speed to push the floating body to the reset end, the control unit sends an extension instruction to the limit plate, and the limit plate extends out of the receiving groove; after the limit plate extends out, the electric push rod retracts. After the water body in the measurement tank stabilizes, the control unit sends a measurement instruction again to retract the inlet valve and the limit plate into the receiving groove, and the floating body starts to move with the water flow.

[0011] Further, in Step 1, the movement range of the floating body is defined in a three-dimensional coordinate system [x, y, z], where: the x-axis is along the water flow direction; the y-axis is perpendicular to the water flow direction; the z-axis is the water depth direction of the measurement tank; the three-dimensional coordinates of the floating body are obtained by the binocular vision principle, and the formula is as follows:

[0012] In the formula, d is the parallax, and the unit is px; is the coordinate of the pixel projection point of the left image; f is the focal length of the camera, and the unit is px; B is the baseline distance between the two cameras, and the unit is m; is the abscissa of the pixel projection point coordinate of the right image. Since the left and right cameras are coplanar, the ordinates of the pixel projection points of the left and right images are the same; is the coordinate of the camera principal point.

[0013] Further, the calculation method of the flow velocity and flow direction in Step 1 includes: Based on the position sequence of the floating body in consecutive frames , calculate the instantaneous flow velocity components:

[0014] In the formula, is the displacement of the floating body within time, and the unit is m; is the time interval between two frames of images, and the unit is s; is the instantaneous velocity component of the floating body in the three-dimensional direction, and the unit is m / s; is the magnitude of the combined flow velocity, and the unit is m / s, representing the actual movement rate of the floating body; is the horizontal flow direction angle, and the unit is radian or degree, representing the angle between the water flow direction and the due north or a preset reference direction; is the pitch angle, and the unit is radian or degree, representing the inclination angle of the water flow in the vertical direction.

[0015] The present invention has the following beneficial effects: The device of the present invention integrates nylon brushes, which can effectively clean suspended matters such as duckweed and blue-green algae on the water surface, reduce the interference of aquatic organisms on the measurement of flow velocity and flow direction, overcome the problems that traditional contact mechanical measurement equipment is easily entangled by water plants and algae, and the probe of contact acoustic measurement equipment is easily attached by algae, and ensures the accuracy and stability of the measurement.

[0016] In view of the unique hydro - hydrodynamic characteristics of "low flow velocity, multi - directionality, and strong disturbance" of small and micro water bodies in the polder area, the device has an adaptive propulsion ability. The driving shaft can drive the propeller according to the instructions of the control unit to move the device in small and micro water bodies, so as to measure the water flow conditions of small and micro water bodies at different positions. At the same time, the depth of the measurement module can be adjusted through the vertical stretching rod, meeting the measurement requirements of flow velocity and flow direction at multiple depths in the complex water flow environment of the polder area.

[0017] The present invention realizes the automatic measurement of multi - directional flow in small and micro water bodies. Processes such as the release of the floating body, photographing, resetting, and real - time transmission of image data are all automatically controlled by the control unit, reducing the intensity of manual operation, improving the measurement efficiency, and enabling long - term unattended monitoring.

[0018] The overall structure of the device is simple, the connection method of each component is stable, and a waterproof design is adopted, which is safe and stable, reducing the maintenance cost and usage difficulty of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is a three - dimensional structural schematic diagram of a multi - directional flow dynamic measurement device for small and micro water bodies in the polder area provided by an embodiment of the present invention; Figure 2 is a right - hand view of a multi - directional flow dynamic measurement device for small and micro water bodies in the polder area provided by an embodiment of the present invention; Figure 3 is a structural schematic diagram of the cleaning module in the present invention Figure 4 is a front view of the floating body reaching the reset end of the measurement box in the present invention; Figure 5 is a front view of the floating body moving with the water flow in the present invention; Figure 6 is a flowchart of a multi - directional flow dynamic measurement method for small and micro water bodies in the polder area.

[0021] Reference numerals: 1 - control unit; 2 - vertical tension rod; 3 - connecting rod; 301 - left output shaft of the motor; 302 - right output shaft of the motor; 4 - waterproof and sealed box; 401 - solar cable; 402 - motor; 5 - propeller; 601 - coupling; 602 - push shaft; 7 - hollow floating ring; 8 - plumb bob; 801 - rope hanger; 9 - measurement module; 10 - cleaning module; 1001 - fixing plate; 1002 - base; 1003 - crank; 1004 - connecting rod; 1005 - fixing bracket; 1006 - nylon brush; 1007 - slider; 1008 - guide rail; 11 - solar panel; 901 - left camera; 902 - right camera; 903 - base of the electric push rod; 904 - electric push rod; 905 - accommodating groove; 906 - floating body; 907 - limiting plate; 908 - inlet valve; 909 - pressure sensor; 910 - fill light; 911 - camera data transmission line; 912 - integrated cable signal line; 913 - transparent partition board. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention. The following will describe in detail the technical solutions provided by each embodiment of the present invention with reference to the drawings.

[0023] Please refer to Figures 1 to 5 , a device for multi-directional dynamic measurement of small and micro water bodies in plain polder areas provided by the present invention, comprising: a hollow floating ring 7 for supporting the measurement device to float on the small and micro water bodies, with lightweight foam filled inside the hollow floating ring 7 to provide stable buoyancy; a counterweight plumb bob 8 is hung behind the side of the hollow floating ring 7 through a rope hanger 801 to ensure the stability of the device in water; a waterproof and sealed box 4 is arranged at the central position on the side of the hollow floating ring 7, and a motor 402 is built in the waterproof and sealed box 4.

[0024] The waterproof and sealed box 4 is sleeved on the connecting rod 3 in the horizontal direction, and the left motor output shaft 301 and the right motor output shaft 302 of the motor 402 are placed inside the connecting rod 3; the fixed plate 1001 is welded to one side of the connecting rod 3; the base 1002 and the guide rail 1008 are welded to the fixed plate 1001; one end of the crank 1003 sleeved on the base 1002 is coaxially and fixedly connected to the left motor output shaft 301, and the other end is connected to the connecting rod 1004 through a hinge; the connecting rod 1004 is fixedly connected to the slider 1007; one end of the fixed frame 1005 is fixedly connected to the slider 1007, and the other end is connected to the nylon brush 1006; the slider 1007 is a rectangular block and slides left and right on the guide rail 1008. The left motor output shaft 301 drives the crank 1003 to make a circular motion, and the crank 1003 pushes the slider to make a linear reciprocating slide on the horizontal guide rail through the connecting rod 1004. At the same time, the slider 1007 transmits the motion to the nylon brush 1006 through the fixed frame 1005 to realize synchronous reciprocating slide to clean the suspended substances on the water surface.

[0025] The right motor output shaft 302 is connected to the push shaft 602 through the coupling 601 to transmit the motor torque; two symmetrically arranged propellers 5 are fixedly installed on the push shaft 602, and the propellers 5 are fixed to the push shaft 602 by key connection or welding; when the motor 402 rotates, the propellers 5 are driven to rotate through the push shaft 602, enabling the equipment to have the ability to move in small and micro water bodies.

[0026] The waterproof and sealed box 4 is sleeved on the vertical stretching rod 2 in the vertical direction, and the vertical stretching rod 2 realizes the lifting function through the guide sleeve fit. By adjusting the height of the vertical stretching rod 2, the accurate measurement of the water flow velocity and direction at different depths of small and micro water bodies can be realized.

[0027] The control unit 1 is fixedly connected above the vertical stretching rod 2 by bolts; the control unit 1 integrates a processor, GPS, an electronic compass and a 4G communication module, and can realize path planning and data encryption. The solar panel 11 is fixedly installed on the top of the vertical stretching rod 2 through a bracket, and the solar panel 11 is connected to the motor 402 through the solar cable 401 to provide continuous energy for the device.

[0028] The measurement module 9 is connected to the vertical stretching rod 2 through a flange; inside the measurement module 9, a transparent partition 913 is installed, and the transparent partition 913 and the side wall of the measurement module together enclose a receiving groove 905; the height of the receiving groove 905 can be the same as the height of the limiting plate 907 and the inlet valve 908; the left camera 901, the right camera 902, and the supplementary light 910 are respectively fixed inside the receiving groove 905 by bolts or card slots; a motorized push rod base 903 is welded to the side wall of the measurement module 9, and a telescopic motorized push rod 904 is fixedly installed on the motorized push rod base 903 through a flange, and a pressure sensor 909 capable of contacting the floating body 906 is installed on the motorized push rod 904. A floating body 906 is arranged on one side of the motorized push rod 904; the measurement module 9 is made of a transparent material, and the movement track of the floating body 906 can be clearly photographed. When measuring the water flow and its direction, the inlet valve 908 and the limiting plate 907 can be moved into the receiving groove 905, and the floating body 906 moves with the movement of the water flow.

[0029] The left camera 901 and the right camera 902 are connected to the control unit 1 through the camera data transmission line 911; the 4G communication module in the control unit 1 transmits the measured image data and the position information of the device to the cloud. The cable signal lines of the motorized push rod 904, the limiting plate 907, the inlet valve 908, and the pressure sensor 909 are arranged along the inner wall of the receiving groove 905, and an integrated cable signal line 912 is led out through the motorized push rod base 903. The integrated cable signal line 912 passes through the inner wall of the vertical stretching rod 2 and is respectively connected to the motor 402 and the control unit 1. The motor 402 supplies power to each component through the multi-strand integrated cable signal line 912; the control unit 1 issues instructions to each component in the measurement module 9 through the integrated cable signal line 912; the control unit 1 issues cleaning and propulsion instructions through the integrated cable signal line 912 and controls the reciprocating movement of the nylon brush 1006 or the start and stop of the propeller 5 through the motor 402. The connection of the camera data transmission line 911 and the integrated cable signal line 912 uses a waterproof connector to ensure the electrical connection stability and safety in a humid environment and prevent faults such as short circuits caused by water ingress.

[0030] As Figure 6 shown, the flowchart of a method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas provided by the present invention shows the complete application process of the present invention from measurement preparation to obtaining results, which is specifically as follows: In the measurement preparation stage, the nylon brush in the cleaning element is used to clean the suspended matter on the water surface to avoid interference with the measurement; the position and direction of the measurement device are determined through GPS and an electronic compass to ensure the accuracy and consistency of the measurement; the depth of the measurement module is adjusted by means of the vertical stretching rod to meet the measurement requirements of water flows at different depths.

[0031] During the measurement phase: After issuing the measurement instruction, the inlet valve and the limit plate move into the receiving groove, and the floating body is released. The floating body starts to move under the action of the water flow. The camera records its movement trajectory, calculates the three-dimensional coordinates of the floating body based on the binocular vision principle, and then calculates the flow velocity and direction, and generates a three-dimensional flow velocity vector diagram.

[0032] During the reset phase, when the movement of the floating body triggers the pressure sensor, the control unit issues a reset instruction, and the electric push rod pushes the floating body to reset. The range of the three-dimensional coordinate system at the reset end of the floating body is defined as [L, y, z]; subsequently, the inlet valve and the limit plate extend out of the receiving groove, completing a measurement cycle. After the electric push rod resets, it waits for the next measurement instruction.

[0033] Among them, the movement range of the floating body is defined as the three-dimensional coordinate system [x, y, z], where: the x-axis is along the water flow direction; the y-axis is perpendicular to the water flow direction; the z-axis is the water depth direction of the measurement box, which is determined by the lifting position of the vertical stretching rod; the three-dimensional coordinates of the floating body are obtained based on the binocular vision principle, and the formula is as follows:

[0034] In the formula, d is the parallax, and the unit is px; is the coordinate of the pixel projection point in the left image; f is the focal length of the camera, and the unit is px; B is the baseline distance between the two cameras, and the unit is m; is the abscissa of the pixel projection point in the right image. Since the left and right cameras are coplanar, the ordinates of the pixel projection points in the left and right images are the same; is the coordinate of the camera principal point.

[0035] Specifically, the calculation method of the flow velocity and direction includes: Based on the position sequence of the floating body in consecutive frames , calculate the instantaneous flow velocity components: In the formula, is the displacement of the floating body within time, and the unit is m; is the time interval between two frames of images, and the unit is s; is the instantaneous velocity component of the floating body in the three-dimensional direction, and the unit is m / s; is the magnitude of the combined flow velocity, and the unit is m / s, representing the actual movement speed of the floating body; is the horizontal flow direction angle, and the unit is radian or degree, representing the angle between the water flow direction and the due north or the preset reference direction; is the pitch angle, and the unit is radian or degree, representing the inclination angle of the water flow in the vertical direction.

[0036] Finally, it should be noted that the above description is only the preferred technical solution and application process of the present invention, and is not intended to limit the present invention. For those skilled in the art, various modifications, substitutions, improvements, etc. to the present invention should all be included within the protection scope of the present invention.

Claims

1. An apparatus for multi-directional dynamic measurement of small water bodies in plain polder areas, characterized in that, A vertical tension rod (2) is provided at the center of the hollow floating ring (7); the control unit (1), the waterproof and sealed box (4), and the measurement module (9) are sleeved on the vertical tension rod (2); a motor (402) is bolted to the bottom of the waterproof and sealed box (4), and the left output shaft (301) of the motor drives a nylon brush (1006) to reciprocate through a crank-slider mechanism composed of a crank (1003), a connecting rod (1004), and a slider (1007); the right output shaft (302) of the motor (402) is connected to a push shaft (602) through a coupling (601), and the push shaft (602) drives the symmetrically arranged propellers (5) on the left and right to rotate, realizing the propulsion function of the device.

2. The device for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 1, wherein, The control unit (1) integrates a processor, a GPS, an electronic compass, and a 4G communication module; the vertical tension rod (2) realizes the lifting function through the cooperation of a guide sleeve; a counterweight plumb bob (8) is hung on the side rear of the hollow floating ring (7) through a rope hanger (801); a solar panel (11) is fixedly installed on the top of the vertical tension rod (2) through a bracket, and the solar panel (11) supplies power to the motor (402) through a solar cable (401).

3. The device for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 2, characterized in that, The measurement module (9) is made of a transparent material and is connected to the vertical tension rod (2) through a flange; the measurement module (9) is provided with an electric push rod base (903), an electric push rod (904), a receiving groove (905), a floating body (906), a limiting plate (907), an inlet valve (908), and a pressure sensor (909); the height of the receiving groove (905) can be the same as the heights of the limiting plate (907) and the inlet valve (908); an electric push rod base (903) is welded on the side wall of the measurement module (9), and a telescopic electric push rod (904) is fixedly installed on the electric push rod base (903) through a flange. The electric push rod (904) is equipped with a pressure sensor (909) that can contact the floating body (906), and a floating body (906) is arranged on one side of the electric push rod (904); a left camera (901), a right camera (902), and a fill light (910) are arranged in the receiving groove (905).

4. The device for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 3, wherein, The left camera (901) and the right camera (902) are connected to the control unit (1) through camera data transmission lines (911); the 4G communication module in the control unit (1) transmits the captured image data and the position information of the device to the cloud.

5. The device for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 4, wherein, The cable signal lines of the electric push rod (904), the limit plate (907), the inlet valve (908), and the pressure sensor (909) are led out along the inner wall of the measurement module (9) through the electric push rod base (903) to form an integrated cable signal line (912); the integrated cable signal line (912) is placed inside the vertical tension rod (2) and is respectively connected to the motor (402) and the control unit (1); the motor (402) supplies power to each component through the multi-strand integrated cable signal line (912); the control unit (1) issues instructions through the integrated cable signal line (912) to control the motor (402) to drive the nylon brush (1006) or the propeller (5), and to conduct coordinated control over each component in the measurement module (9).

6. A method for multi-directional dynamic measurement of small and micro water bodies in plain polder areas, which is applied to the device for multi-directional dynamic measurement of small and micro water bodies in plain polder areas as described in claim 5, characterized in that, Including: Step 1, in the initial state, the limit plate (907) and the inlet valve (908) are outside the accommodation groove (905), and the electric push rod (904) is in the retracted state; after the control unit (1) issues a measurement instruction, the limit plate (907) and the inlet valve (908) move into the accommodation groove (905), and the floating body (906) starts to move under the action of the water flow to be measured; the left camera (901) and the right camera (902) record the movement trajectory of the floating body and calculate the flow velocity and flow direction; 7. The method for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 6, characterized in that In the formula, d is the parallax, with the unit of px; is the coordinate of the pixel projection point of the left image; f is the focal length of the camera, with the unit of px; B is the baseline distance between the two cameras, with the unit of m; is the abscissa of the pixel projection point coordinate of the right image. If the left and right cameras are coplanar, then the ordinates of the pixel projection points of the left and right images are the same; is the coordinate of the camera principal point.

8. The method for multi-directional dynamic measurement of small water bodies in plain polder areas according to claim 6, characterized in that, Step 2, when the floating body (906) contacts the electric push rod (904) and triggers its pressure sensor (909), the pressure sensor (909) outputs a signal indicating the arrival of the floating body to the control unit (1); subsequently, the control unit (1) sends an extension instruction to the electric push rod (904) and the inlet valve (908), and the inlet valve (908) extends outside the accommodation groove (905); Step 3, after the electric push rod (904) extends uniformly to push the floating body (906) to the reset end, the control unit (1) sends an extension instruction to the limit plate (907), and the limit plate (907) extends outside the accommodation groove (905); after the limit plate (907) extends, the electric push rod (904) retracts. After the water body in the measurement tank stabilizes, the control unit (1) sends a measurement instruction again to retract the inlet valve (908) and the limit plate (907) into the accommodation groove (905), and the floating body (906) starts to move with the water flow. In the said Step 1, the movement range of the floating body is defined as a three-dimensional coordinate system [x, y, z], where: the x-axis is along the water flow direction; the y-axis is perpendicular to the water flow direction; the z-axis is the water depth direction of the measurement tank; the three-dimensional coordinates of the floating body are obtained through the binocular vision principle, and the formula is as follows: The flow velocity and flow direction calculation method in the said Step 1 includes: Sequence of floating body positions based on consecutive frames , calculate the instantaneous flow velocity components: In the formula, is the displacement of the floating body within time, with the unit of m; is the time interval between two frames of images, with the unit of s; is the instantaneous velocity component of the floating body in three-dimensional directions, with the unit of m / s; is the magnitude of the synthetic flow velocity, with the unit of m / s, representing the actual movement rate of the floating body; is the horizontal flow direction angle, with the unit of radian or degree, representing the angle between the water flow direction and the due north or a preset reference direction; is the pitch angle, with the unit of radian or degree, representing the inclination angle of the water flow in the vertical direction.

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