LiDAR-based water level detection method, foreign object detection method, and system

Abstract

This invention provides a water level detection method, a water surface foreign object detection method, and a system based on lidar. The current water level is obtained based on the changes in the number of lidar point cloud lines on each pillar. The arrangement of the pillars includes: acquiring the lowest and highest points of the water level that the lidar can detect; determining the horizontal distance between the lidar and each pillar around it; dividing the area into multiple angle ranges based on the lidar's illumination angle; grouping the pillars according to these angle ranges; and performing distance correction on the pillars within each group to ensure that each pillar in the group meets a preset water level detection accuracy. For two adjacent groups within the angle range, the pillar closest to the lidar in the group with the larger tilt angle and the pillar farthest from the lidar in the group with the smaller tilt angle must meet the preset water level detection accuracy. This invention improves the accuracy of the water level detection results.

Description

Technical Field

[0001] This invention relates to the field of water level detection technology, and in particular to a water level detection method, foreign object detection method and system based on lidar. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Real-time water level monitoring technology has a positive impact on coastline safety, marine environmental research, and marine engineering construction. This technology can ensure maritime traffic safety by providing timely and accurate wave information to help ships navigate safely; it can further study issues such as marine ecology, climate change, and marine disasters; through lidar detection technology, it can provide a clearer understanding of the marine environment, thus supporting marine resource development; and it can perform refined measurements of wave height distribution in sea areas, providing crucial data support for marine engineering construction such as offshore wind power and marine water conservancy.

[0004] Common wave height meters include pressure wave height meters, laser rangefinder wave height meters, and microwave wave height meters. Existing equipment for real-time water level monitoring is easily affected by complex hydrological environments, such as changes in climate conditions, tidal fluctuations, wind and waves, and other factors. It often fails to meet the application requirements of high precision, high accuracy, and high frequency. Furthermore, the above equipment cannot monitor the surface conditions in the river channel (such as dangerous activities like swimming and fishing).

[0005] LiDAR offers high-precision monitoring while maintaining good compatibility with harsh environments. It is less affected by wind, waves, bubbles, and water density, and its measurement is unaffected by the color or shape of objects. Therefore, it can be applied to the detection and measurement of objects of various shapes and colors. It can be used in various environments, such as low light, rain, snow, dust, or other particle interference. Utilizing the principle that lidar cannot detect the water surface but can detect other media, it can simultaneously monitor water levels and detect foreign object intrusion.

[0006] However, the inventors discovered that most existing lidar liquid level testing methods directly use lidar to acquire point cloud data, then segment the point cloud data to obtain the liquid surface point cloud data, and thus achieve water level detection. This detection method requires a relatively complex point cloud data processing algorithm, and for different environmental conditions, the scheme of directly segmenting the point cloud data is very prone to inaccurate final water level detection results due to differences in the collected point cloud data. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a water level detection method, a foreign object detection method, and a system based on lidar. By rationally arranging multiple pillars around the lidar, all-weather water level detection is achieved while meeting the accuracy requirements of lidar water level detection. This reduces the impact of environmental factors on water level detection accuracy and improves the accuracy of water level detection results.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a water level detection method based on lidar.

[0010] A water level detection method based on lidar, wherein the lidar is positioned above the water area to be detected, and multiple pillars are arranged around the lidar, including the following process:

[0011] The current water level is determined by the change in the number of lidar point cloud lines on each pillar. The positional arrangement of each pillar includes:

[0012] The goal is to obtain the lowest and highest points of the water level that the lidar can detect, and to determine the horizontal distance between the lidar and the various pillars around it.

[0013] The laser radar is divided into multiple angle ranges, and the columns are grouped according to the angle range. The distance of the columns in each group is corrected so that each column in the group meets the preset water level detection accuracy.

[0014] For two groups with adjacent angle ranges, the column closest to the lidar in the group with the larger tilt angle and the column farthest from the lidar in the group with the smaller tilt angle meet the preset water level detection accuracy.

[0015] As a further limitation of the first aspect of the present invention, the lowest point of water level that the lidar can detect is obtained by combining the highest and lowest water level values ​​of the water area to be detected over the years with the illumination angle below the horizontal line of the lidar.

[0016] Based on the distance between the nearest pillar and the lidar, and combined with the angular difference between adjacent laser beams of the lidar, the highest point of water level that the lidar can detect is obtained.

[0017] As a further limitation of the first aspect of the invention, the distance correction of the columns within each group includes:

[0018] The minimum water level is determined, and the horizontal distance between the column and the lidar is obtained by combining the preset water level detection accuracy and the corresponding illumination angle of the column.

[0019] As a further limitation of the first aspect of the present invention, the preset water level detection accuracy is: the difference between the product of the Nth column and its corresponding illumination angle and the product of the (N-1)th column and its corresponding illumination angle.

[0020] As a further limitation of the first aspect of the present invention, when the water level reaches a certain height atan(θ / 2), θ is the total illumination tilt angle of the lidar, and the real-time water level is determined based on the column closest to the lidar.

[0021] Secondly, the present invention provides a water level detection system based on lidar.

[0022] A water level detection system based on lidar, wherein the lidar is positioned above the water area to be detected, and multiple pillars are arranged around the lidar, including:

[0023] The water level detection module is configured to determine the current water level based on the changes in the number of lidar point cloud lines on each column. The positional arrangement of each column includes:

[0024] The goal is to obtain the lowest and highest points of the water level that the lidar can detect, and to determine the horizontal distance between the lidar and the various pillars around it.

[0025] The laser radar is divided into multiple angle ranges, and the columns are grouped according to the angle range. The distance of the columns in each group is corrected so that each column in the group meets the preset water level detection accuracy.

[0026] For two groups with adjacent angle ranges, the column closest to the lidar in the group with the larger tilt angle and the column farthest from the lidar in the group with the smaller tilt angle meet the preset water level detection accuracy.

[0027] Thirdly, the present invention provides a method for detecting foreign objects on the water surface based on lidar.

[0028] A method for detecting foreign objects on the water surface based on lidar includes the following steps:

[0029] The distance between the current lidar and the water surface is obtained using the lidar-based water level detection method according to the first aspect of the present invention;

[0030] The foreign object detection range of the lidar is determined based on the lidar's maximum detection distance and the current distance between the lidar and the water surface. Foreign object detection is then performed based on the lidar point cloud data within the detection range.

[0031] Fourthly, the present invention provides a water surface foreign object detection system based on lidar.

[0032] A lidar-based foreign object detection system for water surfaces includes:

[0033] The distance detection module is configured to: obtain the current distance between the lidar and the water surface using the lidar-based water level detection method according to the first aspect of the present invention;

[0034] The foreign object detection module is configured to: determine the foreign object detection range of the lidar based on the lidar's farthest detection distance and the current distance of the lidar from the water surface, and perform foreign object detection based on the lidar point cloud data within the detection range.

[0035] Fifthly, the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps in the lidar-based water level detection method as described in the first aspect of the present invention; or, when executed by a processor, the program implements the steps in the lidar-based water surface foreign object detection method as described in the third aspect of the present invention.

[0036] In a sixth aspect, the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the lidar-based water level detection method as described in the first aspect of the present invention; or, the processor executes the program to implement the steps in the lidar-based water surface foreign object detection method as described in the third aspect of the present invention.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] 1. This invention innovatively proposes a water level detection scheme based on lidar. By rationally arranging multiple pillars around the lidar, it achieves all-weather water level detection while meeting the accuracy requirements of lidar water level detection, reduces the impact of environmental factors on water level detection accuracy, and improves the accuracy of water level detection results.

[0039] 2. This invention innovatively proposes a water level detection scheme based on lidar. The columns are grouped, and corrections are first made within each group and then between adjacent groups to ensure that the detection accuracy requirements are met for each column within a group and between columns in adjacent groups. This effectively avoids the impact of changes in the illumination angle on the detection accuracy and achieves continuous water level detection while ensuring the required detection accuracy. Attached Figure Description

[0040] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0041] Figure 1This is a schematic diagram of the installation of the lidar and the column on the water surface according to Embodiment 1 of the present invention;

[0042] Figure 2 This is a top view of the laser radar and column installation schematic diagram provided in Embodiment 1 of the present invention;

[0043] Figure 3 This is a schematic diagram of each rod in each point cloud bundle provided in Embodiment 1 of the present invention;

[0044] Figure 4 This is a schematic diagram illustrating the accuracy issues caused by adding columns as the angle decreases, as provided in Embodiment 1 of the present invention.

[0045] Figure 5 The detection range (front view) of the lidar for detecting floating foreign objects provided in Embodiment 3 of the present invention;

[0046] Figure 6 The detection range (top view) of the lidar for detecting floating foreign objects provided in Embodiment 3 of the present invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0049] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0050] Example 1:

[0051] Embodiment 1 of the present invention provides a water level detection method based on lidar. The lidar is located above the water area to be detected, and multiple pillars are arranged around the lidar. This embodiment takes a 32-line lidar as an example, with the 16th laser line as the horizontal laser line (i.e., the 0° laser line), and includes the following process:

[0052] S1: First, install a lidar at a certain height above the water surface and calibrate the lowest and highest points of the water level that the lidar can detect.

[0053] Methods for selecting the installation height of a lidar system include:

[0054] S1.1: Determine the minimum installation height of the lidar based on the highest water level during high tide in previous years. The installation height shall not be less than the highest water level in previous years.

[0055] S1.2: Determine the lidar model to determine the angle difference between two adjacent laser beams and the overall illumination angle;

[0056] S1.3: Substitute into the formula to obtain the lowest water level that the lidar can detect;

[0057] S1.4: Within a certain distance, the lidar can detect the water level within a certain range of accuracy in a single pole. When the installation distance between the nearest pole and the lidar is a meters, the highest water level value can be determined according to the formula.

[0058] The formula for calculating the minimum water level critical value is as follows: The formula for determining the highest water level is a*tan1°, where H 最高 H is the highest water level in history. 最低 This is the lowest water level in history.

[0059] S2: Determine the installation distance of each column based on the lowest and highest points of the water level that can be detected by the lidar, and install columns around the lidar to determine the height relative to the nearby columns.

[0060] The selection of column installation locations includes:

[0061] S2.1: The installation height of the column must be higher than that of the lidar by more than 1° at the downward tilt angle.

[0062] S2.2: Install a column at a location close to the lidar according to the required accuracy. Control the distance 'a' between the column and the nearest column using the lidar's water level sensing accuracy to obtain the highest water level value that the lidar can detect.

[0063] S2.3: Deploy n pillars around the lidar and determine the distance of each pillar from the lidar;

[0064] S2.4: When a ray at a downward tilt angle of 16° illuminates the column furthest from the lidar, the point that disappears in the lidar point cloud image is the lowest water level height that the lidar can detect.

[0065] In this embodiment, the schematic diagram of the column and the lidar is as follows: Figure 1 and Figure 2 As shown, the minimum installation height of each column is L. n ×tan1°(L n (The horizontal distance from the laser radar to the column), with an accuracy of b. n When the distance is meters, the installation distance of the nearest pole needs to meet the following requirements.

[0066] To ensure the accuracy of lidar data acquisition, the column spacing is rearranged every 4°. The arrangement method is as follows: first, the lowest water level value H is determined, and then the water level height point is increased by H+b based on the accuracy.n At this point, relying on the formula The distance between the columns was calculated.

[0067] S3: Determine the benchmark for water level changes based on the changes in the water level to be monitored, and determine the corresponding relationship of water level height based on the properties of the laser beam of the lidar.

[0068] Determine the corresponding heights of water levels, including:

[0069] S3.1: Based on the determined column spacing, check whether the accuracy of every 4° meets the required accuracy standard. If it does not meet the standard, the process of S2 needs to be repeated to determine the installation distance of the columns.

[0070] S3.2: It is stipulated that the planned columns within every 4° are a column group, and the accuracy between two adjacent column groups is checked to see if it meets the requirements.

[0071] S3.3: Calculate the number of detected water level changes caused by the corresponding column changes within each 4° range, and obtain the real-time water level within each 4° range by accumulating the lowest water level;

[0072] S3.4: When the water level rises or falls further, during the transition phase between each column group, the water level change point cloud references the number of point cloud lines of the adjacent poles.

[0073] The schematic diagram of each member in each point cloud bundle is as follows: Figure 3 As shown, the formula for the correspondence between the lidar laser beam and the water surface (H) n The water level height at an angle of n° is The accuracy formula is b n =L n tann°-L n-1 tan(n°-1°).

[0074] The accuracy formula for the transition phase between column group 1 and column group 2 is as follows:

[0075] c n =L 1组中距离最近杆 tan(minimum angle) - L 2组中的距离最远杆 tan(maximum angle);

[0076] The angles of each laser beam in group L1 are larger than those in group L2.

[0077] S4: Correct the specific point cloud length in the point cloud image to obtain the real-time water level height.

[0078] S4.1: Determine the distances corresponding to each column in the imaging of the lidar host computer or ROS system;

[0079] S4.2: Scenario of column point cloud when marking the lowest water level;

[0080] S4.3: Calibrate the point cloud quantity relationship of the corresponding column when the water level reaches a certain height;

[0081] S4.4: When the water level rises, the change in the number of dot cloud lines in the column is used to judge the water level change;

[0082] S4.5: Calculate the foreign object detection range under different water levels based on the installation height of the lidar.

[0083] Specifically, in the lowest water level scenario, the farthest column has n-1 laser beams and the second farthest column has n laser beams (the size of n is determined by the installation height of the column, and cannot exceed the total number of laser beams of the lidar, and cannot be less than half of the total number of laser beams of the lidar). When there are different column groups, assuming that group 1 is the group with a larger tilt angle, it is divided into three columns 1, 2, and 3 according to the distance from far to near, while group 2 is the group with a smaller tilt angle, and is similarly divided into three columns 4, 5, and 6.

[0084] When there are n-1 point cloud lines on column 3, and n point cloud lines on column 4 in group 2, then the water level is calculated by adding b4 to the water level of column 3. When the water level reaches a certain value... At this time, θ is the total illumination tilt angle of the lidar, and the real-time water level height can be determined simply by identifying the column closest to the lidar.

[0085] Example 2:

[0086] Embodiment 2 of the present invention provides a water level detection system based on lidar. The lidar is located above the water area to be detected, and multiple pillars are arranged around the lidar, including:

[0087] The water level detection module is configured to determine the current water level based on the changes in the number of lidar point cloud lines on each column. The positional arrangement of each column includes:

[0088] The goal is to obtain the lowest and highest points of the water level that the lidar can detect, and to determine the horizontal distance between the lidar and the various pillars around it.

[0089] The laser radar is divided into multiple angle ranges, and the columns are grouped according to the angle range. The distance of the columns in each group is corrected so that each column in the group meets the preset water level detection accuracy.

[0090] For two groups with adjacent angle ranges, the column closest to the lidar in the group with the larger tilt angle and the column farthest from the lidar in the group with the smaller tilt angle meet the preset water level detection accuracy.

[0091] The working method of the system is the same as that of the water level detection method based on lidar provided in Example 1, and will not be repeated here.

[0092] Example 3:

[0093] Embodiment 3 of the present invention provides a method for detecting foreign objects on the water surface based on lidar, comprising the following steps:

[0094] The water level detection method based on lidar according to Embodiment 1 of the present invention obtains the current distance between the lidar and the water surface;

[0095] The foreign object detection range of the lidar is determined based on the lidar's maximum detection distance and the current distance between the lidar and the water surface. Foreign object detection is then performed based on the lidar point cloud data within the detection range.

[0096] Specifically, when detecting foreign objects at a specific point, the principle of lidar imaging on other media, where there is no point cloud data on the water surface, is utilized for identification. First, the distance between the lidar and the water surface = lidar installation height - water surface height, where L... 最近角 L represents the maximum angle of the lidar. 最远角 It can be calculated using the following formula:

[0097]

[0098] Using the area formed by the nearest and farthest angles as the radius, the presence of foreign objects on the water surface within this range can be monitored. The detection range is as follows: Figure 5 and Figure 6 As shown, the blue area represents the detection range of foreign object intrusion by the lidar.

[0099] Example 4:

[0100] Embodiment 4 of the present invention provides a water surface foreign object detection system based on lidar, comprising:

[0101] The distance detection module is configured to: obtain the current distance between the lidar and the water surface using the lidar-based water level detection method according to Embodiment 1 of the present invention;

[0102] The foreign object detection module is configured to: determine the foreign object detection range of the lidar based on the lidar's farthest detection distance and the current distance of the lidar from the water surface, and perform foreign object detection based on the lidar point cloud data within the detection range.

[0103] Example 5:

[0104] Embodiment 5 of the present invention provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, it implements the steps in the water level detection method based on lidar as described in Embodiment 1 of the present invention; or, when the program is executed by a processor, it implements the steps in the water surface foreign object detection method based on lidar as described in Embodiment 3 of the present invention.

[0105] Example 6:

[0106] Embodiment 6 of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the water level detection method based on lidar as described in Embodiment 1 of the present invention; or, when the processor executes the program, it implements the steps in the water surface foreign object detection method based on lidar as described in Embodiment 3 of the present invention.

[0107] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0108] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0109] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0111] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water level detection method based on lidar, characterized in that, The lidar is positioned above the water area to be detected, and multiple pillars are arranged around it. The process includes the following steps: The current water level is determined based on the changes in the number of lidar point cloud lines on each pillar. The positional arrangement of each pillar includes: The goal is to obtain the lowest and highest points of the water level that the lidar can detect, and to determine the horizontal distance between the lidar and the various pillars around it. The laser radar is used to divide the illumination angle into multiple angle ranges. The columns are grouped according to the angle range. The distance of the columns in each group is corrected so that each column in the group meets the preset water level detection accuracy. The preset water level detection accuracy is the difference between the product of the Nth column and its corresponding illumination angle and the product of the (N-1)th column and its corresponding illumination angle. For two groups with adjacent angle ranges, the column closest to the lidar in the group with the larger tilt angle and the column farthest from the lidar in the group with the smaller tilt angle meet the preset water level detection accuracy.

2. The water level detection method based on lidar as described in claim 1, characterized in that, Based on the highest and lowest water levels of the water area to be detected over the years, and combined with the illumination angle below the horizontal line of the lidar, the lowest point of water level that the lidar can detect is obtained. Based on the distance between the nearest pillar and the lidar, and combined with the angular difference between adjacent laser beams of the lidar, the highest point of water level that the lidar can detect is obtained.

3. The water level detection method based on lidar as described in claim 1, characterized in that, Distance adjustments were made to the columns within each group, including: The minimum water level is determined, and the horizontal distance between the column and the lidar is obtained by combining the preset water level detection accuracy and the corresponding illumination angle of the column.

4. The water level detection method based on lidar as described in any one of claims 1-3, characterized in that, When the water level reaches a certain height hour, The real-time water level is determined by the column closest to the lidar.

5. A water level detection system based on lidar, characterized in that, The lidar is positioned above the water area to be detected, and multiple pillars are arranged around it, including: The water level detection module is configured to determine the current water level based on the changes in the number of lidar point cloud lines on each column. The positional arrangement of each column includes: The goal is to obtain the lowest and highest points of the water level that the lidar can detect, and to determine the horizontal distance between the lidar and the various pillars around it. The laser radar is used to divide the illumination angle into multiple angle ranges. The columns are grouped according to the angle range. The distance of the columns in each group is corrected so that each column in the group meets the preset water level detection accuracy. The preset water level detection accuracy is the difference between the product of the Nth column and its corresponding illumination angle and the product of the (N-1)th column and its corresponding illumination angle. For two groups with adjacent angle ranges, the column closest to the lidar in the group with the larger tilt angle and the column farthest from the lidar in the group with the smaller tilt angle meet the preset water level detection accuracy.

6. A method for detecting foreign objects on the water surface based on lidar, characterized in that, Includes the following processes: The water level detection method based on lidar according to any one of claims 1-4 obtains the current distance between the lidar and the water surface; The foreign object detection range of the lidar is determined based on the lidar's maximum detection distance and the current distance between the lidar and the water surface. Foreign object detection is then performed based on the lidar point cloud data within the detection range.

7. A surface foreign object detection system based on lidar, characterized in that, include: The distance detection module is configured to: obtain the current distance between the lidar and the water surface using the lidar-based water level detection method according to any one of claims 1-4; The foreign object detection module is configured to: determine the foreign object detection range of the lidar based on the lidar's farthest detection distance and the current distance of the lidar from the water surface, and perform foreign object detection based on the lidar point cloud data within the detection range.

8. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the lidar-based water level detection method as described in any one of claims 1-4; or, when the program is executed by the processor, it implements the steps in the lidar-based water surface foreign object detection method as described in claim 6.

9. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the water level detection method based on lidar as described in any one of claims 1-4; or, when the processor executes the program, it implements the steps in the water surface foreign object detection method based on lidar as described in claim 6.

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