Underwater building detection system and method

Abstract

The underwater building detection system comprises a laser scanning radar and a processing terminal, different positions of a bridge pier are scanned through the laser scanning radar, the distances of different position points of the bridge pier relative to the laser scanning radar are obtained, and scanning data are sent to the processing terminal. The processing terminal is provided with an image positioning module and a navigation positioning module, underwater space coordinates of the processing terminal are positioned through the navigation positioning module, meanwhile, image data of the laser scanning radar are collected through the image positioning module, and the posture and the relative position of the laser scanning radar are determined through a binocular vision positioning method. The underwater space coordinates of the laser scanning radar are determined through coordinate conversion in combination with the underwater space coordinates of the processing terminal, and the underwater space coordinates of different underwater position points of the pier in the geographic space coordinate system can be determined in combination with the attitude, the scanning angle and the scanning data of the laser scanning radar. And a basis is provided for geometric shape and structural feature analysis of the underwater part of the bridge.

Description

Technical Field

[0001] The present invention relates to the technical field of positioning detection using electromagnetic wave reflection, and particularly to an underwater building detection system and method. Background Art

[0002] In recent years, with the vigorous development of transportation infrastructure, the construction of bridges has been in full swing. Bridge engineering construction has been developing towards larger spans, deeper foundations, and higher bridge towers, which reflects the rapid progress of China's bridge construction level. However, it also poses higher requirements and brings many difficulties to the inspection and maintenance of bridges.

[0003] Bridges are important infrastructure for ensuring social safety and functions. Direct damage to bridges caused by natural disasters will disrupt the transportation system, hinder rescue activities, and cause huge economic losses to society. Since the technical condition of underwater bridge piers cannot be inspected in detail and effectively during daily inspections and regular inspections of bridges, the technical condition of underwater bridge piers is an unstable factor for the safe operation of bridges, especially for bridge piers in large rivers and other areas with fast water flow velocities, riverbed scouring, and changes. To ensure the safe operation of bridges and eliminate unstable factors, it is particularly necessary to detect underwater bridge piers. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides an underwater building detection system and method, which can collect three-dimensional point cloud data of the underwater part of a bridge, providing a basis for the analysis of the geometric shape and structural characteristics of the underwater part of the bridge. The specific technical solutions are as follows:

[0005] In the first aspect, an underwater building detection system is provided. In the first implementable manner of the first aspect, it includes:

[0006] A lidar, configured to scan an underwater building to obtain corresponding point cloud data;

[0007] A processing terminal, provided with:

[0008] An image positioning module, configured to obtain image data of the lidar in real time and determine the relative position of the lidar relative to the processing terminal according to the image data;

[0009] A navigation and positioning module, configured to locate the underwater space coordinates of the processing terminal in real time, and determine the underwater space coordinates corresponding to each point in the point cloud data through coordinate transformation according to the underwater space coordinates and the relative position.

[0010] Combined with the first implementation manner of the first aspect, in the second implementation manner of the first aspect, the lidar is provided with an optical marker, and the image positioning module determines the relative position of the lidar with respect to the processing terminal according to the image position of the optical marker in the image data.

[0011] Combined with the second implementation manner of the first aspect, in the third implementation manner of the first aspect, the optical marker includes a plurality of optical marker balls, and the image positioning module determines the relative position of the lidar according to the image coordinates of each optical marker ball in the image data.

[0012] Combined with the second implementation manner of the first aspect, in the fourth implementation manner of the first aspect, the optical marker is connected to the lidar through an adjustable bracket.

[0013] Combined with the fourth implementation manner of the first aspect, in the fifth implementation manner of the first aspect, the adjustable bracket is detachably connected to the lidar.

[0014] Combined with the fourth or fifth implementation manner of the first aspect, in the sixth implementation manner of the first aspect, the processing terminal is further provided with:

[0015] An electromagnetic positioning module configured to determine the position coordinates of the lidar with respect to the optical marker by using an electromagnetic positioning method;

[0016] The processing terminal determines the relative position of the lidar with respect to the processing terminal through coordinate transformation according to the position coordinates of the lidar with respect to the optical marker and the image position of the optical marker.

[0017] Combined with the first implementation manner of the first aspect, in the seventh implementation manner of the first aspect, the navigation and positioning module includes:

[0018] A satellite navigation unit configured to periodically determine the water space coordinates of the processing terminal;

[0019] An inertial navigation unit configured to measure the inertial navigation data of the processing terminal underwater in real time and locate the underwater space coordinates of the processing terminal in combination with the water space coordinates.

[0020] In a second aspect, an underwater building detection method is provided. In the first implementation manner of the second aspect, it includes:

[0021] Scanning an underwater building with a lidar to obtain corresponding point cloud data;

[0022] The processing terminal obtains the image data of the lidar in real time and locates the underwater space coordinates of the processing terminal in real time;

[0023] Determine the relative position of the lidar with respect to the processing terminal based on the image data, and combine the underwater space coordinates and the relative position to determine the underwater space coordinates corresponding to each point in the point cloud data.

[0024] Combined with the first implementation manner of the second aspect, in the second implementation manner of the second aspect, the real-time positioning of the underwater space coordinates of the processing terminal includes:

[0025] Timely determine the above-water space coordinates of the processing terminal through the satellite navigation unit, and measure the inertial navigation data of the processing terminal underwater in real time through the inertial navigation unit;

[0026] Locate the underwater space coordinates of the processing terminal by combining the above-water space coordinates and the inertial navigation data.

[0027] Combined with the first implementation manner of the second aspect, in the third implementation manner of the second aspect, the determination of the relative position of the lidar according to the image data includes:

[0028] Use the electromagnetic positioning method to determine the position coordinates of the lidar relative to the optical marker;

[0029] Locate the image position of the optical marker according to the image data;

[0030] Combine the image position of the optical marker and the position coordinates of the lidar relative to the optical marker, and determine the relative position of the lidar relative to the processing terminal through coordinate transformation.

[0031] Beneficial effects: By using the underwater building detection system and method of the present invention, the underwater foundation of the bridge pier is scanned by the lidar to obtain the three-dimensional point cloud data of the underwater foundation of the bridge pier relative to the lidar. At the same time, the processing terminal can, through the image positioning module and the navigation positioning module, real-time locate its own underwater space coordinates and obtain the image data of the lidar. The processing terminal can, through the image data, real-time locate the relative position of the lidar relative to the processing terminal, and combine its own underwater space coordinates to real-time locate the underwater space coordinates of the lidar. Finally, based on the real-time underwater space coordinates of the lidar, the position coordinates of each point in the three-dimensional point cloud data are converted into underwater space coordinates through coordinate transformation, providing a basis for the analysis of the geometric shape and structural characteristics of the underwater part of the bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments will be briefly introduced below. In all the drawings, the elements or parts do not necessarily draw according to the actual scale.

[0033] Figure 1 Schematic diagram of the system structure of the underwater building detection system provided by an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the structure of the lidar provided by an embodiment of the present invention;

[0035] Figure 3 Flowchart of the underwater building detection method provided by an embodiment of the present invention;

[0036] Reference numerals:

[0037] 1 - Lidar, 2 - Processing terminal, 3 - Optical marker, 4 - Optical marker ball, 5 - Adjustable bracket, 6 - Mounting post, 7 - Probe. Detailed implementation manners

[0038] Hereinafter, embodiments of the technical solutions of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and thus are only examples and cannot be used to limit the protection scope of the present invention.

[0039] As Figure 1 shown in the schematic diagram of the system structure of the underwater building detection system, the detection system includes:

[0040] Lidar 1, configured to scan an underwater building to obtain corresponding point cloud data;

[0041] Processing terminal 2, provided with:

[0042] Image positioning module, configured to obtain the image data of lidar 1 in real time, and determine the relative position of lidar 1 relative to the processing terminal 2 according to the image data in real time;

[0043] Navigation positioning module, configured to locate the underwater space coordinates of the processing terminal 2 in real time, and determine the underwater space coordinates corresponding to each point in the point cloud data through coordinate transformation according to the underwater space coordinates and the relative position.

[0044] Specifically, the detection system includes a lidar 1 and a processing terminal 2. Among them, the detection personnel can hold the lidar 1 and dive into the water to scan the underwater bridge pier. During the scanning process, the detection personnel can hover in the water and hold the lidar 1 to scan different positions of the bridge pier to obtain the distances of different positions of the underwater part of the bridge pier relative to the lidar 1. The lidar 1 establishes a data connection with the lidar 1 through a data transmission line, and can send the collected data to the processing terminal 2.

[0045] The processing terminal 2 can be fixedly installed on the diving helmet worn by the detector, and is provided with an image positioning module and a navigation positioning module. Among them, the navigation positioning module can accurately and real-time locate the underwater space coordinates of the processing terminal 2, and the underwater space coordinates also represent the position coordinates of the detector. The detector can be navigated through the located underwater space coordinates. The image positioning module is provided with a binocular camera. Through the image data collected by the binocular camera, the image positioning module can use the binocular vision positioning method to determine the attitude of the lidar 1 in real time and its relative position relative to the processing terminal 2.

[0046] The processing terminal 2 can combine the underwater space coordinates of the processing terminal 2 and the relative position of the lidar 1 relative to the processing terminal 2 to determine the underwater space coordinates of the lidar 1, that is, the geospatial coordinates, through coordinate transformation. Then, by combining the attitude of the lidar 1, the set scanning angle, and the distances of different position points relative to the lidar 1, the underwater space coordinates of different position points in the geospatial coordinate system can be determined, providing a basis for the analysis of the geometric shape and structural characteristics of the underwater part of the bridge.

[0047] In this embodiment, optionally, as Figure 2 shown, the lidar 1 is provided with an optical marker 3, and the image positioning module determines the relative position of the lidar 1 relative to the processing terminal 2 according to the image position of the optical marker 3 in the image data.

[0048] Specifically, due to the complex underwater environment, the detection and matching of the feature points of the lidar 1 will be affected to a certain extent. In order to quickly and accurately identify the feature points, an optical marker 3 with obvious features can be set on the lidar 1. The image positioning module can quickly and accurately identify and locate the image position of the optical marker 3 in the image data, and then accurately locate the relative position of the lidar 1 relative to the processing terminal 2.

[0049] In this embodiment, optionally, the optical marker 3 includes a plurality of optical marker balls 4, and the image positioning module determines the relative position of the lidar 1 according to the image coordinates of each optical marker ball 4 in the image data.

[0050] Specifically, the optical marker 3 includes three distinct optical marker balls 4. The image positioning module can quickly and accurately identify and locate the image coordinates of the matching optical marker 3 in the left and right image data collected by the binocular camera, calculate the parallax therefrom, and then obtain the relative position of the lidar 1 with respect to the processing terminal 2 using the binocular vision ranging principle. At the same time, the image positioning module can adopt existing pose estimation algorithms, such as the PnP algorithm, to determine the pose of the lidar 1 during the scanning process based on the image coordinates and position coordinates of the optical marker balls 4. By increasing the number of optical marker balls 4, the number of feature points participating in the identification and positioning of the lidar 1 can be increased, thereby improving the identification and positioning accuracy of the lidar 1.

[0051] In this embodiment, optionally, the optical marker 3 is connected to the lidar 1 through an adjustable bracket 5.

[0052] Specifically, one end of the adjustable bracket 5 can be connected to the lidar 1, and the other end can be connected to the optical marker 3. The detector can adjust the relative position of the optical marker 3 and the lidar 1 through the adjustable bracket 5, so that all the optical marker balls 4 of the optical marker 3 are within the field of view of the binocular camera, avoiding occlusion of the optical marker balls 4 by other objects, thereby ensuring that the left and right image data collected by the binocular camera contain all the optical marker balls 4 and ensuring the identification and positioning accuracy of the lidar 1.

[0053] In this embodiment, optionally, the adjustable bracket 5 is detachably connected to the lidar 1. Specifically, mounting posts 6 are provided at multiple different positions on the outer shell of the lidar 1. One end of the adjustable bracket 5 is provided with a jack, and through the jack, the adjustable bracket 5 can be inserted onto the mounting post 6. If all the optical marker balls 4 cannot be within the field of view of the binocular camera at the current position through the adjustable bracket 5, the adjustable bracket 5 can be detached from the current position and inserted onto the mounting post 6 at other positions for debugging.

[0054] In this embodiment, optionally, the processing terminal 2 is further provided with:

[0055] An electromagnetic positioning module, configured to determine the position coordinates of the lidar 1 relative to the optical marker 3 using an electromagnetic positioning method;

[0056] The processing terminal 2 determines the relative position of the lidar 1 with respect to the processing terminal 2 through coordinate transformation based on the position coordinates of the lidar 1 relative to the optical marker 3 and the image position of the optical marker 3.

[0057] Specifically, after the inspector adjusts the position of the optical marker 3 through the adjustable bracket 5, the relative position relationship between the optical marker 3 and the lidar 1 changes. To locate the relative position of the lidar 1 through the optical marker 3, it is necessary to recalibrate the relative position relationship between the optical marker 3 and the lidar 1 after the position of the optical marker 3 is adjusted.

[0058] For this purpose, the processing terminal 2 can also be provided with an electromagnetic positioning module. This electromagnetic positioning module can generate an electric field with a known electromagnetic intensity distribution. The probe 7 with an electromagnetic sensor at its tip is used to contact each optical marker ball 4 and each mounting post 6 on the lidar 1. The electromagnetic intensity at each optical marker ball 4 and mounting post 6 can be detected through the electromagnetic sensor, and the position coordinates of each optical marker ball 4 and mounting post 6 relative to the processing terminal 2 can be determined through the electromagnetic intensity. Since the relative position between the mounting post 6 and the lidar 1 is fixed, the position coordinates of the lidar 1 relative to the optical marker 3 can be determined through the position coordinates of each optical marker ball 4 and mounting post 6 relative to the processing terminal 2.

[0059] Compared with locating the position coordinates of the lidar 1 relative to the optical marker 3 through the image positioning module, using the electromagnetic positioning method for positioning does not require collecting image data in a dim underwater environment and using a complex matching algorithm to detect and match the feature points of the lidar 1, and is suitable for accurately locating the position coordinates of the lidar 1 relative to the optical marker 3 in a dim underwater environment.

[0060] In this embodiment, optionally, the navigation and positioning module includes:

[0061] A satellite navigation unit configured to periodically determine the water surface space coordinates of the processing terminal 2;

[0062] An inertial navigation unit configured to measure the inertial navigation data of the processing terminal 2 underwater in real time and locate the underwater space coordinates of the processing terminal 2 in combination with the water surface space coordinates.

[0063] Specifically, due to the influence of water, the satellite signal underwater is weak. Using traditional satellite positioning to locate the geographical space coordinates of the underwater processing terminal 2 results in low underwater space positioning accuracy. For this reason, underwater, acoustic positioning and navigation, inertial positioning and navigation, geomagnetic positioning and navigation, and their combinations are generally used to locate the position of underwater targets. And acoustic positioning and navigation requires arranging acoustic beacons in the water, with high deployment costs. With inertial navigation positioning, the error will become larger and larger over time. Geomagnetic positioning and navigation requires accurate measurement of the magnetic field distribution in the detection area in the early stage and is easily affected by electromagnetic interference.

[0064] To this end, this embodiment combines satellite navigation and positioning technology with inertial navigation and positioning technology to comprehensively position the geospatial coordinates of the processing terminal 2, without the need to deploy costly beacons and establish a prior magnetic field database for the detection area. Specifically, the navigation and positioning module is provided with a satellite navigation unit and an inertial navigation unit. Among them, the satellite navigation unit can be a GNSS positioning unit. When the detector floats to the water surface, the satellite navigation unit can be used to position the water surface space coordinates of the processing terminal 2. When the detector dives, the water surface space coordinates of the processing terminal 2 at the moment before entering the water can be used as the initial position, and the underwater space coordinates of the processing terminal 2 after entering the water can be positioned in combination with the inertial navigation data measured in real time by the inertial navigation unit.

[0065] When the detector stays underwater for a time reaching the set time threshold, the detector can float to the water surface, reposition the water surface space coordinates of the processing terminal 2 through the satellite navigation unit, and re-combine the inertial navigation data measured in real time by the inertial navigation unit to position the underwater space coordinates of the processing terminal 2 after entering the water, so as to ensure the positioning accuracy of the underwater space coordinates of the processing terminal 2.

[0066] As Figure 3 shown in the flowchart of the underwater building detection method, the detection method includes:

[0067] Step 1: Scan the underwater building with the lidar 1 to obtain corresponding point cloud data. At the same time, the processing terminal 2 obtains the image data of the lidar 1 in real time and locates the underwater space coordinates of the processing terminal 2 in real time;

[0068] Step 2: Determine the relative position of the lidar 1 relative to the processing terminal 2 according to the image data, and combine the underwater space coordinates and the relative position to determine the underwater space coordinates corresponding to each point in the point cloud data.

[0069] Specifically, first, the detector can hold the lidar 1 and dive into the water to scan the underwater bridge pier. During the scanning process, the detector can hover in the water and hold the lidar 1 to scan different positions of the bridge pier to obtain the distances of different positions of the underwater part of the bridge pier relative to the lidar 1. The lidar 1 establishes a data connection with the lidar 1 through a data transmission line and can send the collected data to the processing terminal 2. When the lidar 1 scans the bridge pier, the processing terminal 2 simultaneously accurately locates the underwater space coordinates of the processing terminal 2 through the navigation and positioning module, and determines the attitude of the lidar 1 and its relative position relative to the processing terminal 2 through the image positioning module.

[0070] Then, the processing terminal 2 can determine the underwater space coordinates of the lidar 1, i.e., the geospatial coordinates, by coordinate transformation in combination with the underwater space coordinates of the processing terminal 2 and the relative position of the lidar 1 with respect to the processing terminal 2. By further combining the attitude of the lidar 1, the set scanning angle, and the distances of different position points with respect to the lidar 1, the underwater space coordinates of different position points in the geospatial coordinate system can be determined, providing a basis for the analysis of the geometric shape and structural characteristics of the underwater part of the bridge.

[0071] In this embodiment, optionally, the real-time positioning of the underwater space coordinates of the processing terminal 2 includes:

[0072] Timely determine the above-water space coordinates of the processing terminal 2 through a satellite navigation unit, and measure the inertial navigation data of the processing terminal 2 underwater in real time through an inertial navigation unit;

[0073] Locate the underwater space coordinates of the processing terminal 2 by combining the above-water space coordinates and the inertial navigation data.

[0074] Specifically, when the detector floats to the water surface, the above-water space coordinates of the processing terminal 2 can be located through the satellite navigation unit. When the detector dives, the above-water space coordinates of the processing terminal 2 at the moment before entering the water can be used as the initial position, and the underwater space coordinates of the processing terminal 2 after entering the water can be located by combining the inertial navigation data measured in real time by the inertial navigation unit.

[0075] When the detector stays underwater for a time reaching the set time threshold, the detector can float to the water surface, re-locate the above-water space coordinates of the processing terminal 2 through the satellite navigation unit, and re-combine the inertial navigation data measured in real time by the inertial navigation unit to locate the underwater space coordinates of the processing terminal 2 after entering the water, thereby ensuring the positioning accuracy of the underwater space coordinates of the processing terminal 2.

[0076] In this embodiment, optionally, determining the relative position of the lidar 1 according to the image data includes:

[0077] Use an electromagnetic positioning method to determine the position coordinates of the lidar 1 relative to the optical marker 3;

[0078] Locate the image position of the optical marker 3 according to the image data;

[0079] Combine the image position of the optical marker 3 and the position coordinates of the lidar 1 relative to the optical marker 3, and determine the relative position of the lidar 1 with respect to the processing terminal 2 through coordinate transformation.

[0080] Specifically, obvious optical markers 3 can be set on the lidar 1. The image positioning module can quickly and accurately identify and locate the image positions of the optical markers 3 in the image data, and then accurately locate the relative position of the lidar 1 relative to the processing terminal 2.

[0081] The optical markers 3 can be set on the lidar 1 through an adjustable bracket 5. The position of the optical markers 3 can be adjusted through the adjustable bracket 5 so that the optical markers 3 are within the field of view of the binocular camera set by the image positioning module. After the tester adjusts the position of the optical markers 3 through the adjustable bracket 5, the electromagnetic intensities at the optical markers 3 and the mounting post 6 can be detected by an electromagnetic sensor, and the position coordinates of the optical markers 3 and the mounting post 6 relative to the processing terminal 2 can be determined through the electromagnetic intensities. Since the relative position between the mounting post 6 and the lidar 1 is fixed, the position coordinates of the lidar 1 relative to the optical markers 3 can be determined through the position coordinates of each optical marker 3 and the mounting post 6 relative to the processing terminal 2.

[0082] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

Claims

1. An underwater building detection system, characterized in that, Comprising: A lidar, configured to scan an underwater building to obtain corresponding point cloud data; A processing terminal, provided with: An image positioning module, configured to acquire the image data of the lidar in real time and determine the relative position of the lidar with respect to the processing terminal according to the image data in real time; A navigation positioning module, configured to locate the underwater space coordinates of the processing terminal in real time, and determine the underwater space coordinates corresponding to each point in the point cloud data through coordinate transformation according to the underwater space coordinates and the relative position.

2. The underwater building detection system according to claim 1, wherein The lidar is provided with an optical marker, and the image positioning module determines the relative position of the lidar with respect to the processing terminal according to the image position of the optical marker in the image data.

3. The underwater building detection system according to claim 2, characterized in that, The optical marker includes a plurality of optical marker balls, and the image positioning module determines the relative position of the lidar according to the image coordinates of each optical marker ball in the image data.

4. The underwater building detection system according to claim 2, wherein The optical marker is connected to the lidar through an adjustable bracket.

5. The underwater building detection system according to claim 4, characterized in that, The adjustable bracket is detachably connected to the lidar.

6. The underwater building detection system according to claim 4 or 5, characterized in that The processing terminal is further provided with: An electromagnetic positioning module, configured to determine the position coordinates of the lidar with respect to the optical marker by using an electromagnetic positioning method; The processing terminal determines the relative position of the lidar with respect to the processing terminal through coordinate transformation according to the position coordinates of the lidar with respect to the optical marker and the image position of the optical marker.

7. The underwater building detection system according to claim 1, wherein, The navigation positioning module includes: A satellite navigation unit, configured to determine the water surface space coordinates of the processing terminal at regular intervals; An inertial navigation unit, configured to measure the inertial navigation data of the processing terminal under the water surface in real time and locate the underwater space coordinates of the processing terminal in combination with the water surface space coordinates.

8. An underwater building detection method, characterized in that, Comprising: Scanning an underwater building by using a lidar to obtain corresponding point cloud data; Acquiring the image data of the lidar by the processing terminal in real time and locating the underwater space coordinates of the processing terminal in real time; Determining the relative position of the lidar with respect to the processing terminal according to the image data, and determining the underwater space coordinates corresponding to each point in the point cloud data in combination with the underwater space coordinates and the relative position.

9. The underwater building detection method according to claim 8, wherein Locating the underwater space coordinates of the processing terminal in real time, including: Determining the water surface space coordinates of the processing terminal at regular intervals through the satellite navigation unit, and measuring the inertial navigation data of the processing terminal under the water surface in real time through the inertial navigation unit; Locating the underwater space coordinates of the processing terminal in combination with the water surface space coordinates and the inertial navigation data.

10. The underwater building detection method according to claim 8, characterized in that, Determining the relative position of the lidar according to the image data, including: Determining the position coordinates of the lidar with respect to the optical marker by using an electromagnetic positioning method; Locating the image position of the optical marker according to the image data; Combining the image position of the optical marker and the position coordinates of the lidar with respect to the optical marker, and determining the relative position of the lidar with respect to the processing terminal through coordinate transformation.

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