Offshore wind power pile foundation scouring detection method based on unmanned ship

Abstract

The invention belongs to the field of pile foundation detection, and discloses an unmanned ship-based offshore wind power pile foundation scour detection method, which comprises the following steps of: S1, transporting an unmanned submarine carrying a sonar scanning device to a target position needing scour detection; s2, the unmanned submarine is released to the sea surface; s3, the wind power pile foundation is scanned by one circle at the depth of the first scanning according to the set scanning distance, and a point cloud set of the first scanning is obtained; s4, the unmanned submarine continues to conduct subsequent scanning; s5, the unmanned submarine is recovered by the unmanned ship; s6, downloading all point cloud sets from the unmanned submarine; s7, modeling the wind power pile foundation based on all the point cloud sets to obtain a three-dimensional model of the wind power pile foundation; and S8, acquiring scouring detection data based on the three-dimensional model. According to the method, the data volume is effectively inhibited, and the calculation efficiency of subsequent scouring detection can be improved.

Description

Technical Field

[0001] The present invention relates to the field of pile foundation detection, and in particular to an offshore wind power pile foundation scour detection method based on an unmanned ship. Background Art

[0002] The wind turbine pile foundation of an offshore wind farm is continuously eroded by seawater, which may reduce the stability of the foundation structure, thus affecting the safety and operation efficiency of the entire wind farm. The traditional way to detect wind turbine pile foundation erosion is to rely on divers to perform manual inspections, but this method is costly, inefficient, and has certain safety risks.

[0003] With the development of unmanned control technology, the technology of using unmanned ships to carry out scour detection of offshore wind turbine pile foundations has gradually emerged. Usually, the unmanned ship transports an unmanned submarine carrying sonar modeling equipment to the vicinity of the wind turbine pile foundation to be inspected, and then the unmanned submarine carries the sonar modeling equipment to perform underwater modeling of the wind turbine pile foundation. The scour situation is determined by analyzing the obtained model.

[0004] Since the underwater part of the wind turbine pile foundation is generally long, it is usually necessary to scan around the wind turbine pile foundation at different depths, and finally merge the data obtained from scanning at different depths to achieve scanning of the entire wind turbine pile foundation.

[0005] However, the prior art generally sets the same overlap ratio between the scanning ranges corresponding to two adjacent scanning depths, without taking into account that different parts of the wind turbine pile foundation are actually affected by scour to different degrees. This can easily lead to the area of ​​the repeated scan being too large, resulting in too long a time spent on subsequent data fusion, affecting the efficiency of obtaining scour detection results. Summary of the invention

[0006] The purpose of the present invention is to disclose an offshore wind turbine pile foundation scour detection method based on an unmanned ship, so as to solve the technical problem of how to determine the overlapping depth between two adjacent scanning depths when scanning the wind turbine pile foundation at different scanning depths, thereby improving the efficiency of obtaining scour detection results.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides an offshore wind power pile foundation scour detection method based on an unmanned ship, comprising:

[0009] S1, the unmanned ship transports the unmanned submarine carrying the sonar scanning device to the target location;

[0010] S2, the unmanned ship releases the unmanned submarine onto the sea surface;

[0011] S3, the unmanned submarine goes to the preset first scanning depth, and scans around the wind power pile foundation at the first scanning depth according to the set scanning distance to obtain a point cloud set of the first scanning;

[0012] S4, the unmanned submarine continues to perform subsequent scanning according to the following control methods, including:

[0013] S41, initialize the value of k to 1;

[0014] S42, calculate the depth dep of the k+1th scan based on the point cloud set obtained by the kth scan k+1 ;

[0015] S43, judging whether the distance to the seabed is less than the set safety distance, if not, proceeding to S44, if yes, proceeding to S46;

[0016] S44, according to the set scanning distance, at the depth dep of the k+1th scanning k+1 Scan around the wind power pile foundation to obtain the point cloud set of the k+1th scan;

[0017] S45, add 1 to the value of k and enter S42;

[0018] S46, rise to the surface;

[0019] S5, the unmanned ship recovers the unmanned submarine;

[0020] S6, download all point cloud sets from the unmanned submarine;

[0021] S7, modeling the wind turbine pile foundation based on all point cloud sets to obtain a three-dimensional model of the wind turbine pile foundation;

[0022] S8, obtaining scour detection data based on the three-dimensional model.

[0023] Preferably, the target position is a position whose distance from the offshore wind power pile is less than a set distance.

[0024] Preferably, releasing the unmanned submarine onto the sea surface comprises:

[0025] The unmanned ship uses a crane to release the unmanned submarine onto the sea surface.

[0026] Preferably, scanning is performed around the wind power pile foundation, including:

[0027] During the orbit, sound wave pulses are continuously emitted for scanning.

[0028] Preferably, the process of determining the preset first scanning depth includes:

[0029] d represents the set scanning distance, and depw represents the length of the scanning area in the vertical direction when the object is scanned along the horizontal direction when the distance between the sonar scanning device and the object is d;

[0030] The depth of the first scan is

[0031] Preferably, the depth dep of the k+1th scan is calculated based on the point cloud set obtained by the kth scan. k+1 ,include:

[0032] Establish a three-dimensional coordinate system according to the set rules;

[0033] Sort the points in the point cloud set obtained by the kth scan in descending order of Z-axis coordinates, with the points with the Z-axis coordinates at the front. The points are stored in the set calu, s is the set value, and nclud represents the total number of points in the point cloud set obtained by the k-th scan;

[0034] Calculate the scan coefficient based on calu;

[0035] Calculate the depth dep of the k+1th scan based on the scan coefficient k+1 .

[0036] Preferably, establishing a three-dimensional coordinate system according to a set rule includes:

[0037] A three-dimensional coordinate system is established with the sea level as the plane formed by the X-axis and the Y-axis, and the direction perpendicular to the sea level and pointing to the seabed as the positive direction of the Z-axis.

[0038] Preferably, the scanning coefficient is calculated based on calu, including:

[0039] The scan factor is calculated using the following formula:

[0040]

[0041] depvr k represents the scanning coefficient calculated based on the point cloud set of the k-th scan, clud represents the point cloud set obtained by the k-th scan, wist i represents the distance between point i and the axis of the wind turbine pile foundation, avewist represents the average distance between the points in clud and the axis of the wind turbine pile foundation, wist max Indicates the maximum value of the distance between the point in the clud and the axis of the wind turbine pile foundation, FTU k Indicates the turbidity of seawater at the kth scan, FTU pre Indicates the preset turbidity, α 1 and α2 represent distance weight and turbidity weight respectively.

[0042] Preferably, the depth dep of the k+1th scan is calculated based on the scan coefficient k+1 ,include:

[0043] Use the following formula to calculate dep k+1 :

[0044]

[0045] dep k It indicates the depth of the kth scan, and depvrc indicates the set scan coefficient comparison value.

[0046] Preferably, the unmanned ship recovers the unmanned submarine, comprising:

[0047] The unmanned ship uses a crane to grab the unmanned submarine and recover it.

[0048] Beneficial effects:

[0049] Compared with the prior art, the present invention does not set the same overlap ratio on the scanning ranges of two adjacent scanning depths when performing scour detection on offshore wind turbine pile foundations, but can calculate the scanning depth of the next scan based on the point cloud data obtained in the previous scan, thereby realizing adaptive change of the scanning depth. When the degree of scouring on the surface of the wind turbine pile foundation at the junction of the two scanning ranges is more serious, a larger overlap ratio can be used to obtain more point cloud data in the area with severe scouring, thereby providing more valid data for subsequent detection calculations; when the degree of scouring on the surface of the wind turbine pile foundation at the junction of the two scanning ranges is less serious, a smaller overlap ratio can be used to reduce the amount of point cloud data finally obtained, thereby realizing effective suppression of the data amount and improving the calculation efficiency of subsequent scour detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0051] Figure 1 It is a schematic diagram of an offshore wind power pile foundation scour detection method based on an unmanned ship according to the present invention.

[0052] Figure 2 A schematic diagram of the process of modeling a wind power pile foundation according to the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The present invention provides an offshore wind power pile foundation scour detection method based on an unmanned ship, comprising:

[0055] S1, the unmanned ship will transport the unmanned submarine carrying the sonar scanning device to the target location.

[0056] Specifically, the target position is a position near the wind power pile foundation that needs to be tested.

[0057] Preferably, the target position is a position whose distance from the offshore wind farm pile is less than a set distance. For example, the set distance is 10 meters. For example, the target position is any point in a circular area with a radius of 10 meters centered on the wind farm pile foundation.

[0058] S2, the unmanned ship releases the unmanned submarine onto the sea surface.

[0059] Specifically, an area for placing an unmanned submarine is provided at the stern of the unmanned ship. The unmanned submarine can be fixed on the unmanned ship by means of a winch or by means of a crane.

[0060] Preferably, releasing the unmanned submarine onto the sea surface comprises:

[0061] The unmanned ship uses a crane to release the unmanned submarine onto the sea surface.

[0062] Specifically, the unmanned ship lifts the unmanned submarine to the sea surface by rotating the crane arm, and then releases the lifting device, and the unmanned submarine falls into the sea surface. The lifting device can be a hook, a clamp, etc.

[0063] S3, the unmanned submarine goes to the preset first scanning depth, and scans around the wind turbine pile foundation at the first scanning depth according to the set scanning distance to obtain the point cloud set of the first scanning.

[0064] Preferably, the unmanned submarine is provided with an automatic control program, which can control the unmanned submarine to reach the depth of the first scan and scan around the wind power pile foundation.

[0065] After circling once, the unmanned submarine returns to the position where it started scanning at that depth.

[0066] Preferably, scanning is performed around the wind power pile foundation, including:

[0067] During the orbit, sound wave pulses are continuously emitted for scanning.

[0068] Preferably, the process of determining the preset first scanning depth includes:

[0069] d represents the set scanning distance, and depw represents the length of the scanning area in the vertical direction when the object is scanned along the horizontal direction when the distance between the sonar scanning device and the object is d;

[0070] When scanning the wind power pile foundation, the horizontal direction is the direction parallel to the sea level;

[0071] The depth of the first scan is

[0072] Specifically, the sonar scanning device can scan an area each time. When the sonar scanning device scans toward the wind power pile foundation at a given scanning distance, the scanning area will have a certain width in the vertical direction (ie, the direction perpendicular to the sea level).

[0073] For example, the value of d may be 2 meters.

[0074] Specifically, the process of generating point cloud data is as follows:

[0075] 1. Sonar emits sound waves

[0076] Transmitter: A sonar system's transmitter (often called a sonar array or sonar transmitter) emits one or more sonic pulses. These sonic pulses are high-frequency sound waves that can travel great distances through water.

[0077] Pulse Selection: The frequency and duration of the sound pulses are determined by the sonar system settings. High-frequency sound waves generally provide higher resolution but travel a shorter distance; low-frequency sound waves have a greater travel distance but lower resolution.

[0078] 2. Sound wave propagation

[0079] Sound wave propagation: Sound waves propagate in water at a certain speed (about 1500 m / s, the specific speed depends on the water temperature, salinity and pressure). When sound waves encounter objects (such as the seabed, obstacles), reflection occurs.

[0080] Propagation path: After the sound wave is emitted from the transmitter, it propagates in a straight line until it encounters the target object (the seabed or other object) and is reflected back.

[0081] 3. Sound wave reception

[0082] Receiver: The receiver in a sonar system (usually a sonar array) picks up the sound waves reflected from the target object. The receiver and transmitter can be the same device or separate devices.

[0083] Signal processing: Sound waves will be attenuated and scattered when they propagate through water. The receiver will receive the echo signal and convert it into an electrical signal.

[0084] 4. Signal conversion and processing

[0085] Analog-to-digital conversion: The received analog sound wave signal will be converted into a digital signal through an analog-to-digital converter for further processing and analysis.

[0086] Signal Enhancement: Digital signals are amplified and de-noised to enhance signal quality and clarity. This step can improve the resolution and accuracy of the data.

[0087] 5. Data Processing

[0088] Time delay measurement: The sonar system measures the time difference between the transmission and reception of sound waves. Since the speed of sound waves in water is known, the distance from the target object to the submarine can be calculated from the time delay.

[0089] Distance calculation: Using the propagation speed and time delay of sound waves, the system can calculate the distance of the sound waves to the target object. This distance is the depth information of the point measured by the sonar.

[0090] 6. Point cloud data generation

[0091] Single point measurement: A single sonar pulse can measure the depth of a single point. Using multiple sonar beams or pulses, the system can acquire data for multiple points in different directions and locations.

[0092] S4, the unmanned submarine continues to perform subsequent scanning according to the following control methods, including:

[0093] S41, initialize the value of k to 1;

[0094] S42, calculate the depth dep of the k+1th scan based on the point cloud set obtained by the kth scan k+1 ;

[0095] S43, judging whether the distance to the seabed is less than the set safety distance, if not, proceeding to S44, if yes, proceeding to S46;

[0096] S44, according to the set scanning distance, at the depth dep of the k+1th scanning k+1 Scan around the wind power pile foundation to obtain the point cloud set of the k+1th scan;

[0097] S45, add 1 to the value of k and enter S42;

[0098] S46, surfacing to the sea surface. After surfacing, the unmanned ship sends its own location to the unmanned ship, so that the unmanned ship can go to the area where the unmanned submarine is located according to the location.

[0099] Specifically, the above control logic is executed by a navigation control device on the unmanned submarine.

[0100] Preferably, the safety distance is set to 0.5 meters.

[0101] Preferably, the depth dep of the k+1th scan is calculated based on the point cloud set obtained by the kth scan. k+1 ,include:

[0102] Establish a three-dimensional coordinate system according to the set rules;

[0103] Sort the points in the point cloud set obtained by the kth scan in descending order of Z-axis coordinates, with the points with the Z-axis coordinates at the front. The points are stored in the set calu, s is the set value, and nclud represents the total number of points in the point cloud set obtained by the k-th scan;

[0104] Calculate the scan coefficient based on calu;

[0105] Calculate the depth dep of the k+1th scan based on the scan coefficient k+1 .

[0106] Specifically, the set value may be 10.

[0107] Preferably, establishing a three-dimensional coordinate system according to a set rule includes:

[0108] A three-dimensional coordinate system is established with the sea level as the plane formed by the X-axis and the Y-axis, and the direction perpendicular to the sea level and pointing to the seabed as the positive direction of the Z-axis.

[0109] Preferably, the scanning coefficient is calculated based on calu, including:

[0110] The scan factor is calculated using the following formula:

[0111]

[0112] depvr k represents the scanning coefficient calculated based on the point cloud set of the k-th scan, clud represents the point cloud set obtained by the k-th scan, wist irepresents the distance between point i and the axis of the wind turbine pile foundation, avewist represents the average distance between the points in clud and the axis of the wind turbine pile foundation, wist max Indicates the maximum value of the distance between the point in the clud and the axis of the wind turbine pile foundation, FTU k Indicates the turbidity of seawater at the kth scan, FTU pre Indicates the preset turbidity, α 1 and α 2 represent distance weight and turbidity weight respectively.

[0113] The scanning coefficient of the present invention is calculated from the distance between the point in the point cloud and the axis, and the turbidity of the seawater during scanning. The greater the fluctuation of the distance between the point in the point cloud and the axis, and the greater the turbidity of the seawater, the greater the scanning coefficient, so that the difference between the calculated k+1 scanning depth and the k+1 scanning depth is smaller, and the area of ​​the repeated scanning area is larger when the two scanning depths are used to scan the wind power pile foundation. In this way, more point cloud data can be obtained for areas with large distance changes.

[0114] The smaller the fluctuation of the distance between the point in the point cloud and the axis, the smaller the turbidity of the seawater, and the smaller the scanning coefficient, the larger the difference between the calculated k+1th scanning depth and the k+1th scanning depth, and the smaller the area of ​​the repeated scanning area when the two scanning depths are used to scan the wind power pile foundation. In this way, the number of point clouds can be reduced.

[0115] Specifically, the axis of the wind turbine pile foundation is a line perpendicular to the sea level where the wind turbine pile foundation is located and passes through the center of the wind turbine pile foundation. The wind turbine pile foundation is generally cylindrical, and the axis of the wind turbine pile foundation is a line passing through the centers of the two end faces of the cylinder formed by the wind turbine pile.

[0116] Preferably, the preset turbidity is 30.

[0117] Preferably, the distance weight and turbidity weight are 0.7 and 0.3, respectively.

[0118] Preferably, the depth dep of the k+1th scan is calculated based on the scan coefficient k+1 ,include:

[0119] Use the following formula to calculate dep k+1 :

[0120]

[0121] dep k It indicates the depth of the kth scan, and depvrc indicates the set scan coefficient comparison value.

[0122] Specifically, the difference between the depth of the k+1th scan and the depth of the kth scan can change with the change of the scan coefficient. When the scan coefficient is larger, the difference is smaller, and when the scan coefficient is smaller, the difference is larger. In this way, the difference between two adjacent scan depths can be adaptively changed with the scan coefficient, and more point cloud data can be obtained for the severely scour area while suppressing the amount of point cloud data obtained overall.

[0123] If the prior art solution is adopted, the value between two adjacent scanning depths will be a fixed value, which easily leads to the situation that too many point clouds are repeatedly obtained for the area less affected by scouring.

[0124] Specifically, the set scanning coefficient contrast value may be 1.01.

[0125] If the existing fixed distance method is used, the bracket part of the above formula is generally a small value, such as 0.6, etc., which will cause the repeated area to be too large.

[0126] S5, unmanned ship recovers unmanned submarine.

[0127] Specifically, the unmanned ship can recover the unmanned submarine through robotic arms, fishing nets, etc.

[0128] Preferably, the unmanned ship recovers the unmanned submarine, comprising:

[0129] The unmanned ship uses a crane to grab the unmanned submarine and recover it.

[0130] A grabbing device is installed on the boom, and the grabbing device grabs a device arranged on the top of the unmanned submarine and used to cooperate with the grabbing device, thereby connecting the unmanned submarine to the boom.

[0131] S6, download all point cloud collections from the unmanned submarine.

[0132] Specifically, the host computer can communicate with the unmanned submarine through a wireless connection or a wired connection, so as to download the point cloud set obtained at all scanning depths from the unmanned submarine.

[0133] S7, modeling the wind turbine pile foundation based on all point cloud sets to obtain a three-dimensional model of the wind turbine pile foundation.

[0134] Specifically, before modeling, the coordinates of all point cloud data are unified.

[0135] Preferably, if Figure 2 As shown, the wind turbine pile foundation is modeled based on all point cloud sets to obtain a three-dimensional model of the wind turbine pile foundation, including:

[0136] De-noise the points in each point cloud set respectively to obtain a de-noised point cloud set;

[0137] Fusing all denoised point cloud sets to obtain a fused point cloud;

[0138] The wind turbine pile foundation is modeled based on the fused point cloud to obtain a three-dimensional model of the wind turbine pile foundation.

[0139] Preferably, denoising is performed on each point in each point cloud set, including:

[0140] De-noise each point in the point cloud set from the X-axis direction, the Y-axis direction and the Z-axis direction respectively, and obtain the X-axis coordinate, Y-axis coordinate and Z-axis coordinate of each point in the point cloud set after de-noising.

[0141] Preferably, performing noise reduction on each point in the point cloud set from the X-axis direction to obtain the X-axis coordinate of each point in the point cloud set after noise reduction includes:

[0142] On the plane formed by the Y axis and the Z axis, the image PX is generated using the X-axis coordinates of the points in the point cloud as pixel values;

[0143] Use the following method to reduce the noise of each pixel in PX and obtain the X-axis coordinate of each pixel after noise reduction:

[0144] Calculate the coefficient of variation of the pixel value of the pixel point in PX;

[0145] If the coefficient of variation is greater than the set coefficient of variation threshold, the first denoising algorithm is used to perform denoising on each pixel in PX respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the X-axis coordinate after denoising; otherwise, the second denoising algorithm is used to perform denoising on each pixel in PX respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the X-axis coordinate after denoising.

[0146] Preferably, performing noise reduction on each point in the point cloud set from the Y-axis direction to obtain the Y-axis coordinate of each point in the point cloud set after noise reduction includes:

[0147] On the plane formed by the X-axis and the Z-axis, the Y-axis coordinates of the points in the point cloud are used as pixel values ​​to generate an image PY;

[0148] Use the following method to denoise each pixel in PY and obtain the Y-axis coordinate of each pixel after denoising:

[0149] Calculate the coefficient of change of the pixel value of the pixel point in PY;

[0150] If the variation coefficient is greater than the set variation coefficient threshold, the first denoising algorithm is used to perform denoising on each pixel in PY respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the Y-axis coordinate after denoising; otherwise, the second denoising algorithm is used to perform denoising on each pixel in PY respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the Y-axis coordinate after denoising.

[0151] Preferably, performing noise reduction on each point in the point cloud set from the Z-axis direction to obtain the Z-axis coordinate of each point in the point cloud set after noise reduction includes:

[0152] On the plane formed by the X-axis and the Y-axis, the Z-axis coordinates of the points in the point cloud are used as pixel values ​​to generate an image PZ;

[0153] Use the following method to reduce the noise of each pixel in PZ and obtain the Z-axis coordinate of each pixel after noise reduction:

[0154] Calculate the coefficient of variation of the pixel values ​​of the pixels in PZ;

[0155] If the coefficient of variation is greater than the set coefficient of variation threshold, the first denoising algorithm is used to perform denoising on each pixel in PZ respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the Z-axis coordinate after denoising; otherwise, the second denoising algorithm is used to perform denoising on each pixel in PZ respectively, and the pixel value of each pixel after denoising is obtained, and the denoised pixel value is used as the Z-axis coordinate after denoising.

[0156] Preferably, the calculation formula of the coefficient of variation is:

[0157]

[0158] vrch represents the coefficient of change of Pa, PXU represents the set of pixels in Pa, NPXU represents the total number of pixels in PXU, pixelv j Indicates the pixel value of pixel j, pixelv max represents the maximum value of the pixel value in PXU, Nbi represents the total number of pixels in PXU whose pixel value is greater than all pixels in the 8-neighborhood, β 1 is the pixel value distribution weight, β 2 is the pixel value difference weight, Pa∈{PX,PY,PZ}.

[0159] Specifically, the variation coefficient of the present invention can effectively represent the variation amplitude of the pixel value in Pa from two different angles. When the standard deviation of the pixel value of the pixel point in Pa is larger, and the number of pixel points whose pixel value is greater than all the pixel points in the 8-neighborhood is larger, the variation coefficient is larger. On the contrary, the variation coefficient is smaller. In this way, a suitable noise reduction algorithm can be selected for PX based on the variation coefficient for noise reduction, thereby avoiding the use of the same noise reduction algorithm for each point in the point cloud set in the X-axis direction, the Y-axis direction and the Z-axis direction. Among these three directions, one is the direction that contains most of the information, while the difference in the coordinate values ​​in the other directions is smaller. Therefore, the present invention can use an algorithm that has a better noise reduction effect but takes longer time to perform noise reduction when the variation coefficient is larger, that is, when the probability that Pa belongs to the direction that contains most of the information is greater. For other directions, a more efficient noise reduction algorithm is used for noise reduction, thereby improving the overall noise reduction efficiency while ensuring the effectiveness of noise reduction.

[0160] Preferably, the pixel value distribution weight is 0.6, and the pixel value difference weight is 0.4.

[0161] Preferably, the coefficient of variation threshold is set to 0.7.

[0162] Preferably, the first noise reduction algorithm is a bilateral filtering algorithm, and the second noise reduction algorithm is a Gaussian filtering algorithm.

[0163] Specifically, the first noise reduction algorithm may also be a guided filtering algorithm, an anisotropic diffusion filtering algorithm, or the like.

[0164] The second noise reduction algorithm may also be a mean filter algorithm or the like.

[0165] The first denoising algorithm is a class of algorithms that can reduce image noise while retaining image edge details. Traditional denoising algorithms such as mean filtering and Gaussian filtering tend to blur edges, while the first denoising algorithm can identify and retain important structures and edge information in the image.

[0166] The process of fusing a point cloud collection includes:

[0167] 1. Coordinate system conversion and alignment:

[0168] Different scanning distances: Scanning at different distances will result in different positions and densities of point cloud data. Therefore, the point cloud data must first be converted to the same coordinate system. Usually, the scanning device itself provides location information or uses an external positioning system (such as GPS, IMU, etc.) to record the position and direction of the device during each scan.

[0169] If there is no direct spatial reference between devices, some algorithms such as ICP (Iterative Closest Point) are needed to align point cloud data collected from different perspectives or at different distances.

[0170] 2. Point Cloud Registration:

[0171] Accurate registration is the core of point cloud fusion. The goal of registration is to perfectly align data from different scanning positions. There are two common registration methods:

[0172] Coarse registration: Perform preliminary point cloud alignment using known landmarks, sensor locations, or manually selected reference points.

[0173] Fine registration: Based on the rough registration, algorithms such as ICP are used to further optimize the point cloud data so that they are more accurately aligned. ICP continuously calculates the distance and error between point clouds through iterations, and gradually adjusts the position, rotation, and scale of the point clouds until the error is minimized.

[0174] 3. Overlapping area optimization

[0175] Different scanning distances may overlap in some areas. The following methods can be used to deal with these overlapping areas:

[0176] Method: The points in the overlapping area can be merged based on a simple averaging strategy, that is, for each group of similar points in the overlapping area, their average position is taken as the new point.

[0177] S8, obtaining scour detection data based on the three-dimensional model.

[0178] Specifically, the newly obtained three-dimensional model A is compared with the three-dimensional model B generated during the last scour detection, and the regions in the three-dimensional model A that are different from B are obtained, and the volumes of the different regions are respectively obtained, thereby obtaining the scour detection data.

[0179] When performing scour detection on offshore wind turbine pile foundations, the same overlap ratio is not set on the scanning ranges of two adjacent scanning depths. Instead, the scanning depth of the next scan can be calculated based on the point cloud data obtained in the previous scan, thereby realizing adaptive changes in the scanning depth. When the degree of scouring on the surface of the wind turbine pile foundation at the junction of the two scanning ranges is more serious, a larger overlap ratio is used to obtain more point cloud data in the area with severe scouring, thereby providing more effective data for subsequent detection calculations; when the degree of scouring on the surface of the wind turbine pile foundation at the junction of the two scanning ranges is less serious, a smaller overlap ratio is used to reduce the amount of point cloud data finally obtained, thereby realizing effective suppression of the data amount and improving the calculation efficiency of subsequent scour detection.

[0180] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for detecting scour of offshore wind power pile foundation based on an unmanned ship, characterized in that: include: S1, the unmanned ship transports the unmanned submarine carrying the sonar scanning device to the target location; S2, the unmanned ship releases the unmanned submarine onto the sea surface; S3, the unmanned submarine goes to the preset first scanning depth, and scans around the wind power pile foundation at the first scanning depth according to the set scanning distance to obtain a point cloud set of the first scanning; S4, the unmanned submarine continues to perform subsequent scanning according to the following control methods, including: S41, initialize the value of k to 1; S42, calculate the depth dep of the k+1th scan based on the point cloud set obtained by the kth scan k+1 ; S43, judging whether the distance to the seabed is less than the set safety distance, if not, proceeding to S44, if yes, proceeding to S46; S44, according to the set scanning distance, at the depth dep of the k+1th scanning k+1 Scan around the wind power pile foundation to obtain the point cloud set of the k+1th scan; S45, add 1 to the value of k and enter S42; S46, rise to the surface; S5, the unmanned ship recovers the unmanned submarine; S6, download all point cloud sets from the unmanned submarine; S7, modeling the wind turbine pile foundation based on all point cloud sets to obtain a three-dimensional model of the wind turbine pile foundation; S8, obtaining scour detection data based on the three-dimensional model.

2. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 1 is characterized in that: The target position is a position where the distance to the offshore wind power pile is less than a set distance.

3. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 1 is characterized in that: Release the unmanned submarine onto the sea surface, including: The unmanned ship uses a crane to release the unmanned submarine onto the sea surface.

4. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 1 is characterized in that: Scan around the wind power pile foundation, including: During the orbit, sound wave pulses are continuously emitted for scanning.

5. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 1 is characterized in that: The process of determining the preset first scanning depth includes: d represents the set scanning distance, and depw represents the length of the scanning area in the vertical direction when the object is scanned along the horizontal direction when the distance between the sonar scanning device and the object is d; The depth of the first scan is 6. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 5 is characterized in that: Calculate the depth dep of the k+1th scan based on the point cloud set obtained from the kth scan k+1 ,include: Establish a three-dimensional coordinate system according to the set rules; Sort the points in the point cloud set obtained by the kth scan in descending order of Z-axis coordinates, with the points with the Z-axis coordinates at the front. The points are stored in the set calu, s is the set value, and nclud represents the total number of points in the point cloud set obtained by the k-th scan; Calculate the scan coefficient based on calu; Calculate the depth dep of the k+1th scan based on the scan coefficient k+1 .

7. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 6 is characterized in that: Establish a three-dimensional coordinate system according to the set rules, including: A three-dimensional coordinate system is established with the sea level as the plane formed by the X-axis and the Y-axis, and the direction perpendicular to the sea level and pointing to the seabed as the positive direction of the Z-axis.

8. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 6 is characterized in that: Calculate the scan coefficients based on calu, including: The scan factor is calculated using the following formula: depvr k represents the scanning coefficient calculated based on the point cloud set of the k-th scan, clud represents the point cloud set obtained by the k-th scan, wist i represents the distance between point i and the axis of the wind turbine pile foundation, avewist represents the average distance between the points in clud and the axis of the wind turbine pile foundation, wist max Indicates the maximum value of the distance between the point in the clud and the axis of the wind turbine pile foundation, FTU k Indicates the turbidity of seawater at the kth scan, FTU pre represents the preset turbidity, α1 and α2 represent the distance weight and turbidity weight respectively.

9. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 8, characterized in that: Calculate the depth dep of the k+1th scan based on the scan coefficient k+1 ,include: Use the following formula to calculate dep k+1 : dep k It indicates the depth of the kth scan, and depvrc indicates the set scan coefficient comparison value.

10. The offshore wind power pile foundation scour detection method based on an unmanned ship according to claim 1, characterized in that: The unmanned ship recovers the unmanned submarine, including: The unmanned ship uses a crane to grab the unmanned submarine and recover it.

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