Underwater riprap particle motion trail measuring device and method

Abstract

The invention relates to the technical field of trajectory measurement, discloses an underwater riprap particle motion trajectory measurement device and method, and aims to realize high-precision response tracking of stress and motion trajectory of riprap particles around a foundation under dynamic water scouring based on an underwater positioning unit sensing array and a high-frequency sampling particle motion and attitude detection technology. The technical problem that the motion characteristics of a single riprap particle cannot be observed in previous riprap protection research is solved. Through combined measurement of acceleration and angular velocity data collected by the inertial measurement unit and absolute position measured by the radio frequency unit, the three-dimensional motion condition, track and attitude process of a unit space as well as two-dimensional displacement images of a riprap surface and a vertical flow section are accurately reconstructed; and a centimeter-level-precision visual data support and a low-cost research means are provided for foundation scouring and coastal slope protection and riprap protection research, so that the engineering cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of trajectory measurement, in particular to an underwater riprap particle motion trajectory measuring device and method. BACKGROUND

[0002] Among the current various scour protection technologies, riprap protection has the advantages of cost economy, strong terrain adaptability, convenient and efficient construction, etc. Without complex equipment and process support, it can be applied to different water depths, seabed topography and geological conditions, and has become the most widely used technical solution in offshore wind power pile foundation scour protection engineering at home and abroad. The technology forms a riprap body by laying a certain particle size and gradation of block stones on the seabed around the pile foundation, and uses the weight and structural integrity of the riprap body to resist wave and current scouring and prevent sediment migration around the pile, thereby achieving protection of the pile foundation.

[0003] Although riprap protection is widely used, its long-term operation stability still faces severe challenges: under the action of continuous waves and currents, the riprap body is prone to multiple forms of damage. On the one hand, the surface layer of the riprap body is directly scoured and impacted by the water flow, which is prone to surface damage such as material loss, local edge scouring and collapse, resulting in a reduction in the protection range and a decrease in the protection effect; on the other hand, the sand filled in the internal pores of the riprap body is prone to escape under the action of wave and current penetration, thereby causing overall settlement and deformation, reducing the structural integrity and protection function of the riprap body.

[0004] Currently, the core bottleneck restricting the long-term stable application of riprap protection technology is the lack of experimental measurement technology for the motion law of the riprap body: the existing technology cannot accurately capture the dynamic response process of the riprap body under the action of waves and currents, resulting in unclear damage mechanism of the riprap body, inability to quantitatively analyze the stress characteristics of riprap particles in different regions, and inability to accurately track the motion trajectory and displacement law of the particles, thereby failing to reveal the induction mechanism and evolution path of the damage forms such as surface scouring and internal settlement. This cognitive limitation directly leads to the current riprap protection engineering design relying on empirical formulas and engineering analogy, lacking quantitative design methods and theoretical support for the long-term operation stability of the riprap body, and being difficult to meet the high-precision requirements of offshore wind power long-term safe operation for protection technology. SUMMARY

[0005] Therefore, the present application provides an underwater riprap particle motion trajectory measuring device and method to solve the problem of how to accurately measure the underwater riprap particle motion trajectory.

[0006] In a first aspect, the present application provides a device for measuring the trajectory of underwater riprap particles, comprising: an underwater positioning system, a three-dimensional spatial positioning system, and a three-dimensional deformation reconstruction system, wherein the underwater positioning system is embedded on the surface and inside the riprap body, and is used to calculate the motion data of the riprap particles; the three-dimensional spatial positioning system is used to set multiple anchor points, communicate with the underwater positioning system, and calculate the absolute position of the underwater positioning system; the three-dimensional deformation reconstruction system is used to correct the motion data of the riprap particles based on the absolute position of the underwater positioning system by using a fusion algorithm, and reconstruct to generate a spatial three-dimensional distribution of the riprap particles, a motion trajectory line, an attitude process, and a two-dimensional displacement image of the surface of the riprap body and the vertical flow direction profile.

[0007] Based on the underwater positioning unit sensor array and the high-frequency sampling particle motion and attitude detection technology, the present application realizes high-precision response tracking of the force and motion trajectory of the riprap particles around the foundation under the hydrodynamic scour, solves the technical problem that the motion characteristics of a single riprap particle cannot be observed in the previous riprap protection research. Through the joint measurement of the acceleration and angular velocity data collected by the inertial measurement unit and the absolute position measured by the radio frequency unit, the spatial three-dimensional motion, the trajectory, the attitude process, and the two-dimensional displacement image of the surface of the riprap and the vertical flow direction profile are accurately reconstructed, which provides cm-level precision visual data support and low-cost research means for the foundation scour and coastal slope protection riprap protection research, so as to save the engineering cost.

[0008] In an optional embodiment, the underwater positioning system comprises: a plurality of underwater positioning units, each of which comprises an inertial measurement unit, a radio frequency unit, a power supply, and a waterproof shell, and the inertial measurement unit, the radio frequency unit, and the power supply are uniformly arranged inside the waterproof shell, wherein the inertial measurement unit is used to measure the acceleration and angular velocity of the underwater positioning unit in real time, and calculate the position, velocity, and attitude of the riprap particles by integration; the radio frequency unit is used to actively emit an ultra-wideband pulse signal, and communicate with the three-dimensional spatial positioning system to calculate the distance between the underwater positioning unit and the three-dimensional spatial positioning system by time difference of arrival.

[0009] In an optional embodiment, the waterproof shell is generated based on the 3D scanning point cloud data of the riprap particles, is made of high-density waterproof material by 3D printing, and the surface is treated by sand blasting coating, the sand blasting coating is made of riprap stone powder, the density of the waterproof shell is consistent with the density of the real riprap particles, and the shape of the waterproof shell is consistent with the shape of the real riprap particles.

[0010] In an alternative embodiment, a plurality of underwater positioning units are arranged in a three-dimensional riprap body and form a spatial monitoring grid covering the circumferential, radial and vertical directions to monitor the movement of riprap particles in different riprap layers and the inner and outer edges of the riprap; the three-dimensional riprap body is a riprap accumulation body formed by uniformly arranging riprap particles around the foundation in a uniform annular shape, or a cemented riprap body after pouring and cementing the cementing material; in the circumferential direction, at least two layers of underwater positioning units are arranged, a preset interval is provided between each circumferential layer, and at least a plurality of underwater positioning units are arranged in each layer; in the radial direction, an angle reference direction is set based on the flow direction, at least three layers are arranged in the angle range between the flow direction and the counter-flow direction, a preset included angle is provided between each radial layer, and at least a plurality of underwater positioning units are arranged in each layer; in the vertical direction, at least two layers of underwater positioning units are arranged, a preset interval is provided between each vertical layer, and at least a plurality of underwater positioning units are arranged in each layer.

[0011] In an alternative embodiment, the three-dimensional deformation reconstruction system includes a fusion algorithm module that fuses the measurement data of the inertial measurement unit and the radio frequency unit using a Kalman filter algorithm, and periodically corrects the integral cumulative error of the inertial measurement unit through the absolute position data of the radio frequency unit; when the radio frequency unit signal is interrupted, the high-frequency data of the inertial measurement unit is used to provide continuous navigation for the underwater positioning unit to fill in the update interval.

[0012] In an alternative embodiment, the anchor points of the three-dimensional spatial positioning system are arranged at both ends of the water tank wall surface and uniformly distributed around the foundation pile, and the anchor point antenna axis points to the center of the foundation bed.

[0013] In a second aspect, the application provides a method for measuring the trajectory of underwater riprap particles, which includes: a three-dimensional spatial positioning system calculating the absolute position of the underwater positioning system; a three-dimensional deformation reconstruction system correcting the motion data of the riprap particles based on the absolute position of the underwater positioning system using a fusion algorithm, and reconstructing to generate the spatial three-dimensional distribution of the riprap particles, the motion trajectory line, the attitude process, and the two-dimensional displacement image of the riprap body surface and the vertical flow direction profile.

[0014] In an alternative embodiment, the process of calculating the displacement of the riprap particles includes: measuring the acceleration and angular velocity of the underwater positioning unit in real time; calculating the position, velocity and attitude of the riprap particles by integration.

[0015] In an alternative embodiment, the process of calculating the displacement of the underwater positioning system includes: calculating the displacement of the underwater positioning system and the absolute position of the underwater positioning system using TDOA ranging according to the time difference of the ultra-wideband pulse signal arriving at each anchor point.

[0016] In an alternative embodiment, the underwater riprap particle trajectory measurement method further comprises: the three-dimensional deformation reconstruction system fuses the measurement data of the inertial measurement unit and the radio frequency unit by using a Kalman filtering algorithm, and regularly corrects the integral cumulative error of the inertial measurement unit by using the absolute position data of the radio frequency unit; when the radio frequency unit signal is interrupted, the continuous navigation of the underwater positioning unit is provided by using the high-frequency data of the inertial measurement unit to fill in the update interval. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 is a composition diagram of the underwater riprap particle trajectory measurement device according to the embodiment of the present application;

[0019] Figure 2 is an anchor point arrangement diagram according to the embodiment of the present application;

[0020] Figure 3 is a waterproof shell schematic diagram according to the embodiment of the present application;

[0021] Figure 4 is a underwater positioning unit arrangement schematic diagram according to the embodiment of the present application;

[0022] Figure 5 is a top view of the underwater positioning unit arrangement according to the embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0024] In order to solve the above problems, the industry has carried out exploration of underwater riprap particle displacement monitoring and test technology, and the existing technology is mainly divided into three categories, but all have obvious limitations:

[0025] Artificial monitoring technology of acoustic wave scanning / camera: This technology periodically observes the surface morphology of the riprap body through underwater acoustic wave detection equipment or camera equipment, and indirectly infers the surface displacement of the riprap body. However, it is only suitable for macroscopic monitoring of the overall morphological change of the riprap body, and cannot obtain micro-movement information of individual particles or local areas. At the same time, the monitoring accuracy is easily disturbed by environmental factors such as water turbidity, bubbles generated by waves and currents, and lighting conditions, and the applicability in high-turbidity and high-flow sea areas is significantly reduced.

[0026] CFD-DEM coupling simulation technology: This technology simulates the wave flow field motion through computational fluid dynamics (CFD), and combines the discrete element method (DEM) to simulate the collision and motion of riprap particles, realizing numerical simulation of the motion process of the riprap body. However, this method needs to solve the complex coupling problem of fluid field and particle field at the same time, and the calculation amount is huge, requiring high hardware computing power. Moreover, the simulation results are highly dependent on the setting of the turbulence model, particle contact model and boundary conditions, and the accuracy and reasonableness of the model parameters directly affect the simulation accuracy, making it difficult to completely reproduce the motion and destruction process of the riprap body in the real marine environment.

[0027] Inertial measurement unit (IMU) embedded monitoring technology: This technology embeds a micro inertial measurement unit in part of the riprap particles to directly collect motion parameters such as acceleration and angular velocity of the particles, and then calculates the particle displacement through integration. However, due to the inherent integral error of inertial measurement, the error will continuously accumulate with the extension of the measurement time, resulting in that this technology is only suitable for short-time scale monitoring of the motion of riprap particles, and cannot meet the accuracy requirements of displacement monitoring during the long-time test or operation of the riprap body.

[0028] In summary, the existing technologies cannot realize accurate measurement and analysis of the stress and motion trajectory of riprap particles in different areas under the action of waves and currents, making it difficult to accurately grasp the real deformation behavior and destruction mechanism of the riprap body, and restricting the improvement of the long-term stability design level of riprap protection projects. Therefore, developing a method that can break through the limitations of existing technologies and realize accurate monitoring of the micro-movement of riprap particles has important theoretical significance and engineering value for clarifying the destruction mechanism of the riprap body, guiding the long-term stability design of riprap protection projects, and ensuring the safety of offshore wind power structures.

[0029] Therefore, in the present embodiment, a device for measuring the motion trajectory of underwater riprap particles is provided, as shown in Figure 1 which includes an underwater positioning system, a three-dimensional space positioning system, and a three-dimensional deformation reconstruction system.

[0030] (1) The underwater positioning system is embedded in the surface and interior of the riprap body, and the underwater positioning system is used to calculate the motion data of the riprap particles.

[0031] Specifically, the underwater positioning system as a "front-end acquisition unit" of particle motion data adopts a distributed embedded design and is integrated into the surface particles and internal particles of the riprap body through modular packaging technology to form a full-coverage monitoring network.

[0032] (2) The three-dimensional spatial positioning system is used to set multiple anchor points and calculate the absolute position of the underwater positioning system.

[0033] Specifically, the three-dimensional spatial positioning system as an "absolute position reference unit" is used to solve the problem that the underwater positioning system can only measure relative displacement and is prone to cumulative errors. The core design idea is to set fixed reference anchor points, establish a global three-dimensional coordinate system, and then calibrate the absolute position of the underwater positioning system.

[0034] The anchor points of the three-dimensional spatial positioning system are arranged at both ends of the water tank wall and are uniformly distributed around the foundation pile, with the anchor point antenna axis pointing to the foundation center bed.

[0035] The three-dimensional spatial positioning system receives the acoustic signals emitted by each anchor point in real time through the acoustic receiving array, calculates the relative position of the underwater positioning system relative to each reference anchor point using the "time difference positioning method", establishes a global three-dimensional coordinate system covering the entire riprap area in combination with the pre-calibrated geodetic coordinates of the reference anchor points, and then establishes a connection with each embedded unit of the underwater positioning system through the underwater acoustic communication link, sends the absolute position signals of 3-4 reference anchor points around each embedded unit, and calculates the absolute position of each embedded unit in the global coordinate system after receiving the signals, thereby completing the absolute reference calibration of the relative displacement data of the underwater positioning system.

[0036] Alternatively, as shown in Figure 2 The three-dimensional spatial positioning system includes four anchor points to ensure that the positioning unit can be detected by no less than three anchor points at any position, is arranged at both ends of the water tank wall, is uniformly distributed around the foundation pile, is 2 m away from the bed, has an anchor point antenna axis pointing to the foundation center bed, and enhances the reception of UWB signals.

[0037] (3) The three-dimensional deformation reconstruction system is used to correct the motion data of the riprap particles based on the absolute position of the underwater positioning system using a fusion algorithm and reconstruct to generate the spatial three-dimensional distribution of the riprap particles, the motion trajectory line, the attitude process, and the two-dimensional displacement image of the riprap body surface and the vertical flow direction profile.

[0038] Specifically, the three-dimensional deformation reconstruction system as a "data fusion and result output unit" undertakes the core tasks of data integration, error correction, and visual presentation. It deeply fuses the particle relative displacement data of the underwater positioning system and the absolute position data of the three-dimensional spatial positioning system through a customized fusion algorithm to finally generate the dynamic deformation characteristics of the riprap body and the particle motion trajectory.

[0039] In an alternative embodiment, the underwater positioning system comprises a plurality of underwater positioning units, each comprising an inertial measurement unit, a radio frequency unit, a power supply and a waterproof housing, as shown in Figure 3 The inertial measurement unit, the radio frequency unit and the power supply are evenly arranged inside the waterproof housing, and the uniform arrangement of each module avoids excessive deviation of the center of gravity of the underwater positioning system.

[0040] (1) The 3D scanning of riprap particles is performed by point cloud technology to obtain sub-millimeter point cloud data of the riprap particles, and an editable 3D model is generated, which is used for making the waterproof shell.

[0041] Specifically, based on the weight similarity principle, the thickness of the sensor shell is adjusted according to the density of the 3D printing material to match the density of the block stone; high-density waterproof material is used for 3D printing, and the surface is treated with sandblasting coating (which can use riprap stone powder) to approach the surface roughness of the real stone block, forming a waterproof shell similar in weight and shape to the physical and mechanical characteristics of the real riprap particles.

[0042] (2) The inertial measurement unit is used to measure the acceleration and angular velocity of the underwater positioning unit in real time, and the position, velocity and attitude of the riprap particle are calculated by integration.

[0043] Specifically, based on the principle of inertial navigation, the inertial measurement unit calculates the motion parameters of the riprap particle by integrating the acceleration and angular velocity data: the calculated position, velocity and attitude data are temporarily stored in the unit buffer area in the form of data packets (including time stamp, parameter value and data check bit), waiting for transmission with the radio frequency unit.

[0044] Specifically, the inertial measurement unit integrates the acceleration data once in the time dimension, combined with the initial velocity (0 when deployed), to obtain the real-time velocity (v x , v y , v z ) of the particle in the three-dimensional coordinate system. During the integration process, high-frequency noise is suppressed by a complementary filtering algorithm to ensure the smoothness of the velocity data.

[0045] Specifically, the inertial measurement unit integrates the calculated velocity data twice, combined with the initial position (initial coordinates recorded when deployed), to obtain the relative displacement (Δx, Δy, Δz) of the particle, and further determine the relative position of the particle.

[0046] Specifically, the inertial measurement unit integrates the collected angular velocity data, combined with the initial attitude angle (roll angle, pitch angle, yaw angle initial value determined by calibration), to calculate the real-time attitude change of the particle in the three-dimensional space. If a magnetometer is integrated, the yaw angle drift can be corrected by the magnetometer data to improve the accuracy of the attitude angle measurement.

[0047] Optionally, the inertial measurement unit measures the acceleration and angular velocity of the underwater positioning unit, the sampling frequency is 100-1000 Hz, the angular velocity cumulative error is <0.01° per revolution, and the position, velocity and attitude are calculated by integration.

[0048] (3) The radio frequency unit communicates with the fixed anchor point of the three-dimensional space positioning system, and the radio frequency unit is used to transmit an ultra-wideband pulse signal to the three-dimensional space positioning system.

[0049] Specifically, the radio frequency unit automatically wakes up according to a preset period, transmits a wake-up signal to the surrounding fixed anchor point, and the fixed anchor point feeds back a response signal after receiving the wake-up signal, and the communication link is established; after the link is established, the radio frequency unit first transmits an ultra-wideband pulse signal to the fixed anchor point, and the signal contains the unique identifier of the underwater positioning system, the relative position data preliminarily calculated by the inertial measurement unit, and the timestamp information.

[0050] To solve the problem that the integral error of the inertial measurement unit will quickly accumulate over time, the inertial measurement unit and the ultra-wideband radio frequency unit are combined for measurement. The ultra-wideband (UWB) radio frequency unit actively transmits an ultra-wideband pulse signal with a frequency of 10-200 Hz, and a static ranging error of 10 mm. The radio frequency unit communicates with the fixed anchor point in the three-dimensional space positioning system, calculates the centimeter-level distance by using the time difference of arrival (TDOA), obtains the absolute position of the underwater positioning unit, and corrects the motion data of the riprap particles obtained by the inertial measurement unit to realize the absolute positioning of the underwater positioning unit. In an actual application scenario, as shown in FIGS. 1 and 2, 21 underwater positioning units are arranged in a three-dimensional riprap body, numbered S1 to S21, forming a spatial monitoring grid in the circumferential and radial directions, for monitoring the motion of riprap particles in different riprap layers and the inner and outer edges of the riprap. Figure 4 、 5 The three-dimensional riprap body is a riprap accumulation body formed by uniformly arranging riprap particles around the foundation, and is preferably a cemented riprap body formed by pouring and cementing a cementing material.

[0051] For the circumferential arrangement, three layers of sensors (i.e., underwater positioning units) are arranged, and the layer spacing is 0.4 m. The inner layer includes S1-S5, S16, S19, a total of 7 underwater positioning units, the middle layer includes S6-S10, S17, S20, a total of 7 underwater positioning units, and the outer layer includes S11-S15, S18, S21, a total of 7 underwater positioning units.

[0052] For the radial direction arrangement, the water flow direction is 180°, the reverse water flow direction is 0°, and five layers are arranged along 0°-180°, and the interlayer angle is 45°. Along the 0° direction, S1, S6, and S11 are arranged as three underwater positioning units; along the 45° direction, S2, S7, and S12 are arranged as three underwater positioning units; along the 90° direction, S3, S8, S13, and S16-S21 are arranged as nine underwater positioning units; along the 135° direction, S4, S9, and S14 are arranged as three underwater positioning units; and along the 180° direction, S5, S10, and S15 are arranged as three underwater positioning units.

[0053] For the vertical direction arrangement, three layers are arranged, and the layer spacing is 0.1 m. The upper layer is arranged with S1-S15, which are 15 positioning units; the middle layer is arranged with S16-S18, which are three positioning units with a spacing of 0.45 m; and the lower layer is arranged with S19-S21, which are three positioning units with a spacing of 0.5 m.

[0054] In the present embodiment, a method for measuring the motion trajectory of underwater riprap particles is provided, which comprises:

[0055] (1) The underwater positioning system calculates the motion data of the riprap particles.

[0056] Optionally, the displacement process of the riprap particles comprises: measuring the acceleration and angular velocity of the underwater positioning unit in real time; and calculating the position, velocity, and attitude of the riprap particles by integration.

[0057] (2) The three-dimensional space positioning system calculates the absolute position of the underwater positioning system.

[0058] The process of calculating the absolute position of the underwater positioning system comprises: calculating the displacement of the underwater positioning system and the absolute position of the underwater positioning system by TDOA ranging according to the time difference of the arrival of the ultra-wideband pulse signal at each anchor point.

[0059] (3) The three-dimensional deformation reconstruction system corrects the motion data of the riprap particles based on the absolute position of the underwater positioning system by using a fusion algorithm, and reconstructs to generate the spatial three-dimensional distribution of the riprap particles, the motion trajectory line, the attitude process, and the two-dimensional displacement image of the riprap body surface and the vertical flow direction profile.

[0060] In some optional embodiments, the inertial measurement and ultra-wideband positioning fusion algorithm uses a Kalman filter algorithm, and the calculation process is as follows:

[0061] (1) Inertial measurement

[0062] Let the state variable of a certain underwater positioning unit be:

[0063] x(t)=[p(t) Τ ,v(t) Τ ,q(t)Τ ,b a (t) Τ ,bg(t) Τ ]

[0064] where p(t) T is the position vector; v(t) T is the velocity vector; q(t) T is the attitude quaternion; b a (t) T is the accelerometer bias; b g (t) T is the gyroscope bias.

[0065] The position change equation is:

[0066]

[0067] The velocity change equation is:

[0068]

[0069] The attitude change equation is:

[0070]

[0071] The bias modeling equation is:

[0072]

[0073] where a m is the acceleration measurement; ω m is the gyroscope measurement; n ba and n bg are the accelerometer noise and gyroscope noise, respectively; g is the gravitational acceleration; Ω is the angular velocity conversion quaternion operator; and R(q) is the rotation matrix corresponding to the quaternion.

[0074] According to the data measured by the inertial unit, a state propagation model of the underwater positioning unit is obtained.

[0075] (2) UWB measurement

[0076] By knowing the anchor position p i , the absolute position can be obtained by measuring the time difference of arrival (TDOA) of the UWB radio unit to multiple anchors:

[0077] ct ij = ||p-p i || - ||p-p j || + n ij

[0078] where c is the electromagnetic wave propagation speed; tij is the time difference between the signal reaching the ith anchor and the jth anchor; p i is the position of the ith anchor; p j is the position of the jth anchor; n ij is the measurement error.

[0079] (3) Joint measurement fusion algorithm

[0080] Time update using inertial measurement unit measurement data:

[0081]

[0082] where, is the updated state estimate; is the predicted state estimate before update; u k is the inertial unit measurement data.

[0083] Predicted state covariance matrix:

[0084]

[0085] where, F k is the Jacobian matrix of the state transition equation; Q k is the process noise covariance.

[0086] Calculate the residual:

[0087]

[0088] where, z k is the predicted distance between the positioning unit and the anchor; is the measured distance between the positioning unit and the anchor.

[0089] Calculate the Kalman gain:

[0090]

[0091]

[0092] where, S k is the residual covariance matrix; H k is the Jacobian matrix of the UWB observation model; R k is the observation noise covariance matrix; K k is the Kalman gain matrix.

[0093] State update:

[0094]

[0095] where, is the updated state estimate of the fusion algorithm.

[0096] Covariance update:

[0097] P k|k = (I - K k H k )P k|k-1

[0098] where I is the identity matrix.

[0099] In an actual application scenario, the embodiment provides the following test process:

[0100] (1) Prepare test materials. Fill the test section with test sand, level the top surface of the sand bed, and slightly raise the elevation of the sand bed above the bottom surface of the water tank to improve sufficient upstream sand supply. In the embodiment, test sand with a median particle size of 0.16 mm is used, and is arranged within a range of 30 m downstream and upstream of a pile foundation with a diameter of 0.5 m.

[0101] (2) Sensor grid layout. After leveling the sand bed, underwater positioning units S19-S21 are arranged at the designed positions on the bed surface, and then riprap is filled to a thickness of 0.1 m, with a riprap body edge slope ratio of 1:1, and a riprap particle size range of 6.25-12.5 mm and a median particle size of 10 mm. After leveling the riprap surface, underwater positioning units S16-S18 are laid out, and then riprap is continuously filled to a thickness of 0.2 m, and after leveling, underwater positioning units S1-S15 are laid out.

[0102] (3) Anchor point fixation. Anchor points are fixed on the side wall of the water tank, at a distance of 2 m from the bed surface in four directions of the foundation, with the anchor point antenna axis pointing to the center of the bed surface. Water is added to the water tank to reach the designed water depth, and the underwater positioning units are calibrated and calibrated by the positioning anchor points.

[0103] (4) Start the test. Start the circulating water pump and adjust to a stable test flow rate.

[0104] (5) Real-time monitoring and processing. The inertial measurement unit collects acceleration and angular velocity data in the motion process of the positioning unit in real time, and updates the position, velocity, and attitude of the positioning unit in real time in combination with the UWB positioning data. The operator can observe the deformation trend of the sensor arrangement section during the test process through the interactive interface.

[0105] (6) Three-dimensional reconstruction of test results. After the test is completed, the topography after scour is reconstructed in three dimensions by a high-resolution industrial camera and three-dimensional reconstruction software. The three-dimensional reconstruction results are compared and corrected with the joint measurement results to obtain the final high-precision spatial three-dimensional distribution of the positioning unit, the motion trajectory line and the attitude process, and the two-dimensional displacement images of the riprap surface and the vertical flow direction profile.

[0106] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A device for measuring the trajectory of underwater stone-throwing particles, characterized in that, include: Underwater positioning system, three-dimensional spatial positioning system, and three-dimensional deformation reconstruction system, among which, The underwater positioning system is embedded in the surface and interior of the boulders, and is used to calculate the motion data of the boulders. The three-dimensional spatial positioning system is used to set multiple anchor points, communicate with the underwater positioning unit system, and calculate the absolute position of the underwater positioning system. The three-dimensional deformation reconstruction system is used to correct the motion data of the boulders based on the absolute position of the underwater positioning system using a fusion algorithm, and reconstructs the spatial three-dimensional distribution, motion trajectory lines, attitude process, and two-dimensional displacement images of the boulders' surface and vertical flow direction profiles.

2. The underwater stone-throwing particle trajectory measuring device according to claim 1, characterized in that, The underwater positioning system includes multiple underwater positioning units. Each underwater positioning unit includes an inertial measurement unit, a radio frequency unit, a power supply, and a waterproof housing. The inertial measurement unit, radio frequency unit, and power supply are evenly arranged inside the waterproof housing. The inertial measurement unit is used to measure the acceleration and angular velocity of the underwater positioning unit in real time, and to calculate the position, velocity and attitude of the boulders by integration; The radio frequency unit is used to actively transmit ultra-wideband pulse signals and communicate with the three-dimensional spatial positioning system, and calculate the distance between the underwater positioning unit and the three-dimensional spatial positioning system by the time difference of arrival.

3. The underwater stone-throwing particle trajectory measuring device according to claim 2, characterized in that, The waterproof shell is a 3D model generated based on 3D scan point cloud data of pebbles. It is 3D printed using high-density waterproof material and the surface is treated with a sandblasting coating made of pebbles powder. The density of the waterproof shell is consistent with that of real pebbles, and the shape of the waterproof shell is consistent with that of real pebbles.

4. The underwater stone-throwing particle trajectory measuring device according to claim 2, characterized in that, The multiple underwater positioning units are deployed in the three-dimensional boulders and form a spatial monitoring grid covering the circumferential, radial and vertical directions to monitor the movement of boulders particles in different boulder layers and on the inner and outer edges of the boulders. The three-dimensional paved body is a paved pile formed by paved particles being uniformly arranged in a ring around the foundation, or a cemented paved body after being cemented with cementing material. In the circumferential direction, the underwater positioning unit is arranged in at least two layers, with a preset spacing between each circumferential layer, and each layer is equipped with at least a number of underwater positioning units. In the radial direction, an angle reference direction is set based on the water flow direction, and at least three layers are arranged along the angle range between the water flow direction and the counter-water flow direction. A preset included angle is set between each radial layer, and at least multiple underwater positioning units are arranged in each layer. In the vertical direction, the underwater positioning unit is arranged in at least two layers, with a preset distance between each vertical layer, and each layer is equipped with at least a number of underwater positioning units.

5. The underwater stone-throwing particle trajectory measuring device according to claim 1, characterized in that, The three-dimensional deformation reconstruction system includes a fusion algorithm module. The fusion algorithm module uses a Kalman filter algorithm to fuse the measurement data of the inertial measurement unit and the radio frequency unit. The absolute position data of the radio frequency unit is used to periodically correct the integral accumulation error of the inertial measurement unit. When the radio frequency unit signal is interrupted, the high-frequency data of the inertial measurement unit is used to provide continuous navigation for the underwater positioning unit to fill the update interval.

6. The underwater stone-throwing particle trajectory measuring device according to claim 1 or 5, characterized in that, The anchor points of the three-dimensional spatial positioning system are arranged at both ends of the water tank wall and evenly distributed around the foundation piles, with the antenna axis of the anchor points pointing towards the center of the foundation bed.

7. A method for measuring the trajectory of underwater stone-thrown particles, characterized in that, include: The underwater positioning system calculates the motion data of the thrown stones; A three-dimensional spatial positioning system calculates the absolute position of an underwater positioning system. The three-dimensional deformation reconstruction system uses a fusion algorithm to correct the motion data of the thrown stone particles based on the absolute position of the underwater positioning system, and reconstructs the spatial three-dimensional distribution, motion trajectory lines, attitude process, and two-dimensional displacement images of the surface of the thrown stone and the cross-section in the vertical flow direction.

8. The underwater stone-throwing particle trajectory measurement method according to claim 7, comprising calculating the displacement process of the stone-throwing particle, including: Real-time measurement of acceleration and angular velocity of underwater positioning units; The position, velocity, and attitude of the boulders are calculated by integration.

9. The method for measuring the trajectory of underwater stone-throwing particles according to claim 7, characterized in that, The process of calculating the absolute position of an underwater positioning system includes: Based on the time difference of the arrival of the ultra-wideband pulse signal at each anchor point, the displacement and absolute position of the underwater positioning system are calculated using TDOA ranging.

10. The method for measuring the trajectory of underwater stone-throwing particles according to claim 7, characterized in that, Also includes: The 3D deformation reconstruction system uses a Kalman filter algorithm to fuse measurement data from the inertial measurement unit (IMU) and the radio frequency (RF) unit. It periodically corrects the integral accumulation error of the IMU using the absolute position data of the RF unit. When the RF unit signal is interrupted, it provides continuous navigation for the underwater positioning unit using the high-frequency data of the IMU to fill the update interval.

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