A three-dimensional laser scanning workbench for measuring damaged areas of underwater objects

Abstract

The present application relates to the technical field of laser scanning, and particularly relates to a three-dimensional laser scanning workbench for measuring damaged areas of underwater objects, comprising: an instrument mounting platform, a suction cup type fixing device and a water bottom auxiliary fixing table; a transparent sealing cover and a supporting leg are arranged on the lower side of the instrument mounting platform, a first mechanical arm is arranged in the sealing cover, a mechanical hand for clamping a scanner is arranged at the end of the first mechanical arm, a second mechanical arm for cleaning is mounted on the supporting leg, and the suction cup type fixing device is mounted on the lower side of the supporting leg; the water bottom auxiliary fixing table comprises a top platform and an inclined supporting leg, the suction cup type fixing device can be adsorbed to the top platform, and an inclined pointed cone capable of being inserted into silt is arranged at the bottom of the inclined supporting leg. Through cooperation of the suction cup type fixing device and the water bottom auxiliary fixing table, relative stillness of the scanner and the target object under different conditions is ensured, and more accurate point cloud data is obtained.

Description

Technical Field

[0001] This invention relates to the field of laser scanning technology, and in particular to a three-dimensional laser scanning stage for measuring the damage area of ​​underwater objects. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Technological advancements have driven marine development, and a series of economic activities have spurred demand for underwater vision and 3D scanning technologies. Since these resource development activities primarily take place at sea, research into underwater laser 3D imaging has become a crucial component of marine development technologies in recent years.

[0004] The most important aspect of underwater 3D laser scanning technology is ensuring accurate point cloud data. To guarantee the accuracy of the point cloud data, the laser scanner and the target object must be kept relatively stationary during the scanning process. In addition, issues such as how to place the laser scanner in the appropriate area, such as how to perform fixed scanning in different situations on the seabed (e.g., areas with sediment accumulation) and off the seabed (e.g., ship hulls, bridge piers), as well as the need to remove marine organisms before scanning, all need to be considered. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a three-dimensional laser scanning stage for measuring the damage area of ​​underwater objects.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] A three-dimensional laser scanning worktable for measuring underwater object damage areas includes: an instrument mounting platform, a suction cup fixing device, and an underwater auxiliary fixing platform; the instrument mounting platform has a transparent sealing cover and legs on its lower side, the legs being located around the transparent sealing cover, a first robotic arm being disposed inside the sealing cover, the end of the first robotic arm being provided with a robotic hand for gripping the scanner, a second robotic arm for cleaning being mounted on the legs, and the suction cup fixing device being mounted on the lower side of the legs; the underwater auxiliary fixing platform includes a top platform and inclined legs, the suction cup fixing device being able to adhere to the top platform, and the bottom of the inclined legs being provided with an inclined cone that can insert into silt.

[0008] Preferably, the upper opening of the transparent sealing cover includes left and right baffles, front and rear baffles and a transparent bottom plate. The upper ends of the left and right baffles and the front and rear baffles are sealed to the top plate of the instrument mounting platform, and the lower ends of the left and right baffles and the front and rear baffles are sealed to the transparent bottom plate. The left and right baffles, the front and rear baffles, the transparent bottom plate and the top plate of the instrument mounting platform form a sealed cavity for the scanner.

[0009] Preferably, a moving unit is provided inside the transparent sealing cover. The moving unit includes a sliding fixed seat, a rolling shaft, and rollers. The first robotic arm is a three-degree-of-freedom robotic arm and is disposed at the bottom of the sliding fixed seat. The sliding fixed seat is sleeved on the rolling shaft, and the rollers are disposed at both ends of the rolling shaft. The inner sides of the left and right baffles are provided with pulley grooves, and the rollers are installed in the pulley grooves.

[0010] Preferably, the second robotic arm is a multi-degree-of-freedom robotic arm, and the second robotic arm is mounted on the platform below the support leg of the instrument mounting platform via a waist joint rotation.

[0011] Preferably, the suction cup fixing device is connected to the support leg of the instrument mounting platform via a ball joint, and a filler layer is provided at the ball joint connection.

[0012] Preferably, the suction cup fixing device includes a fixing sleeve, a suction cup, a connecting tube, and a negative pressure bottle. The fixing sleeve is fixed to the bottom of the support leg of the instrument mounting platform, the suction cup is disposed inside the fixing sleeve, and the negative pressure bottle is connected to the suction cup through the connecting tube.

[0013] Preferably, the negative pressure bottle is provided with a piston push rod, the piston push rod includes a piston and a rod end, the piston and the body of the negative pressure bottle are provided with a second sealing ring, the rod end is sleeved with a spring, one end of the spring abuts against the piston and the other end abuts against the body of the negative pressure bottle.

[0014] Preferably, the inclined support leg of the underwater auxiliary fixing platform includes a first rod, a second rod, and a hydraulic telescopic rod. The upper end of the first rod is fixed to the top platform, the lower end of the first rod is rotatably connected to the second rod, the inclined cone is set at the bottom of the second rod, and one end of the hydraulic telescopic rod is connected to the first rod and the other end is connected to the second rod.

[0015] Preferably, the transparent base plate is provided with a connector and a driven gear. The connector includes a fixing part and a rotating part. The fixing part is strip-shaped and embedded in the transparent base plate. The rotating part is cylindrical and rotatably connected to the front and rear baffles. The driven gear is fixed on the transparent base plate. The front and rear baffles are provided with a driving gear. The driving gear meshes with the driven gear and drives the transparent base plate to rotate relative to the left and right baffles.

[0016] Preferably, the inner sides of the left and right baffles are provided with deformable parts, the left and right ends of the transparent base plate are arc-shaped surfaces, the arc-shaped surfaces of the transparent base plate cooperate with and are sealed to the deformable parts of the left and right baffles, and the bottom of the left and right baffles also have inwardly protruding flanges.

[0017] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0018] This invention utilizes a mounting platform equipped with suction cups to mount a 3D laser scanning device for scanning underwater scenes, such as underwater ship hulls, underwater bridge piers, and other structures or equipment that are not on the seabed and are inconvenient to fix for scanning. This allows the scanner to remain relatively stationary with the object without damaging it, thus obtaining accurate point cloud data. For underwater targets, such as mooring chains or underwater oil pipelines in environments with sediment buildup, a corresponding underwater auxiliary mounting platform is used to complete the scanning task. Additionally, a multi-degree-of-freedom robotic arm is mounted on each side of the mounting platform to address the issue of attachment to marine organisms.

[0019] Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a front view of the instrument mounting platform according to an embodiment of the present invention;

[0023] Figure 2 This is a top view of the instrument mounting platform according to an embodiment of the present invention;

[0024] Figure 3 This is a bottom view of the instrument mounting platform according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the suction cup fixing device according to an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the sliding fixed seat push rod and the transparent sealing cover in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the connection between the instrument mounting platform legs and the suction cup fixing device in an embodiment of the present invention;

[0028] Figure 7 This is a front view of the underwater auxiliary fixing platform according to an embodiment of the present invention;

[0029] Figure 8 This is a top view of the underwater auxiliary fixing platform according to an embodiment of the present invention;

[0030] Figure 9 This is a flowchart illustrating the process of an embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of the refractive model of the underwater sealing device according to an embodiment of the present invention;

[0032] Figure 11 This is a schematic diagram of the cooperation between the transparent base plate and the left and right baffles in an embodiment of the present invention;

[0033] Figure 12 This is a schematic diagram of the transparent base plate driving according to an embodiment of the present invention;

[0034] In the diagram: 1. First sealing ring; 2. Suction cup; 3. Sealing gasket; 4. Fixing sleeve; 5. Tightening bolt; 6. Buckle; 7. Tightening nut; 8. Connecting pipe; 9. Negative pressure bottle; 10. Second sealing ring; 11. Piston push rod; 12. Spring; 13. Handle; 14. Sliding fixed seat; 15. Three-degree-of-freedom robotic arm; 16. Soft robotic hand; 17. Multi-degree-of-freedom robotic arm; 171. Waist joint; 18. Roller; 19. 20. Pulley groove; 21. Arched cross; 22. Transparent sealing cover; 23. Left and right baffles; 24. Transparent base plate; 25. Front and rear baffles; 26. Sliding fixed seat push rod; 27. Mechanical claw interface; 28. Connector; 29. ​​Driven gear; 20. Driven gear; 21. Stop block; 22. Slip ring; 33. Rotating shaft; 34. Laser emitter; 35. Light receiver; 36. Inclined cone; 37. Hydraulic telescopic rod;

[0035] The distances or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0036] 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 in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] For ease of description, the terms "front," "rear," "left," "right," "up," and "down" appearing in this invention only indicate that they are consistent with the front, rear, left, right, up, and down directions of the accompanying drawings themselves. They do not limit the structure and are merely for the purpose of facilitating the description of this invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Terminology Explanation: The terms "installation," "connection," "linking," and "fixing" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to an internal connection between two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0040] One embodiment of the present invention provides a three-dimensional laser scanning worktable for measuring the damage area of ​​underwater objects, comprising: an instrument mounting platform, a suction cup fixing device, and an underwater auxiliary fixing platform; the instrument mounting platform is provided with a transparent sealing cover 21 and a support leg on its lower side, the support leg being located around the transparent sealing cover 21, a first robotic arm being provided inside the sealing cover, the end of the first robotic arm being provided with a robotic hand for holding the scanner, and a second robotic arm for cleaning being installed on the support leg, specifically, the second robotic arm being installed below the platform body next to the support leg. The suction cup fixing device is installed on the lower side of the support leg; the underwater auxiliary fixing platform includes a top platform and an inclined support leg, the suction cup fixing device being able to adhere to the top platform, and the bottom of the inclined support leg being provided with an inclined cone 32 that can be inserted into silt.

[0041] The laser scanner is clamped by a three-degree-of-freedom robotic arm 15 equipped with a soft robotic arm 16. The soft robotic arm 16 ensures that the laser scanner is not damaged during the clamping process.

[0042] After loading the laser scanner, install the transparent sealing cover 21. The transparent sealing cover 21 is used to isolate underwater sediment from affecting the internal rolling structure of the platform. The transparent sealing cover 21 has a groove at the point of contact with the sliding fixed seat push rod 22. Figure 5 As shown, polytetrafluoroethylene filler is placed inside the groove to achieve a reciprocating dynamic seal between the push rod and the transparent sealing cover 21, thereby achieving the purpose of the push rod moving without affecting the sealing performance of the transparent sealing cover 21.

[0043] like Figure 1 , Figure 2 As shown, the work platform carrying the 3D laser scanner is connected to the ROV system's mechanical gripper via a mechanical gripper interface 23 located in the middle of its housing. The mechanical gripper interface 23 contains an arched cross 20 to facilitate clamping between the interface and the ROV's mechanical gripper. The ROV system is used to dive and deploy the work platform device. Simultaneously, the diver manually assists in placing and securing the work platform device using handle 13, finding a suitable placement position.

[0044] like Figure 4 As shown, the suction cup fixing device includes a fixing sleeve 4, a suction cup 2, a connecting pipe 8, and a negative pressure bottle 9. The fixing sleeve 4 is fixed to the bottom of the support leg of the instrument mounting platform. The suction cup 2 is disposed inside the fixing sleeve 4, and a sealing gasket 3 is disposed between the suction cup 2 and the fixing sleeve 4. The negative pressure bottle 9 is connected to the suction cup 2 through the connecting pipe 8. A piston push rod 11 is disposed inside the negative pressure bottle 9. The piston push rod 11 includes a piston and a rod end. A second sealing ring 10 is disposed between the piston and the body of the negative pressure bottle 9. A spring 12 is sleeved on the rod end. One end of the spring 12 abuts against the piston, and the other end abuts against the body of the negative pressure bottle 9.

[0045] During operation, the ROV system's robotic arm and the entire workbench are fixedly connected to the ROV system via the robotic claw interface 23 on the outside of the mounting platform. After being transported to the target area, it is deployed. With the help of multi-degree-of-freedom robotic arms 17 on both sides inside the instrument mounting platform, the surface of the target being scanned is cleaned of any adhering substances. The workbench uses suction cup fixing devices and a matching underwater auxiliary fixing platform to adhere to or fix the area around the underwater target under different conditions, ensuring that the laser scanner remains relatively stationary with respect to the target, thereby obtaining more accurate point cloud data.

[0046] Underwater 3D laser scanning is divided into two types: underwater targets and non-underwater targets. For non-underwater scanning: The first sealing ring 1 of the suction cup 2 fixing device on the worktable is tightly attached to a suitable position. The working switch of the suction cup fixing device is turned on, driving the piston push rod 11, which has a second sealing ring 10 at its head, to move. This compresses the spring 12 in the middle of the piston push rod 11, and the upward movement of the piston push rod 11 generates negative pressure in the bottle cavity, thereby drawing water from the suction cup 2 into the negative pressure bottle 9, thus putting the cavity of the suction cup 2 into a negative pressure state and fixing the worktable. A valve structure is provided at the connection between the connecting pipe 8 and the fixing sleeve 4. The valve structure adopts a snap-fit ​​fixing structure, including a snap 6, a tightening nut 7, and a tightening bolt 5. The valve structure is connected to the inlet of the negative pressure bottle 9 and the port of the suction cup 2 fixing sleeve 4, realizing the connection between the negative pressure bottle and the suction cup device.

[0047] By attaching the suction cup 2 to the wall of an underwater object and turning on the control switch, the motor runs, driving the piston push rod 11 in the negative pressure bottle 9 connected to the suction cup 2, drawing water between the suction cup 2 and the wall of the underwater object into the negative pressure bottle 9, creating a negative pressure. This causes the suction cup 2 and the target object to be subjected not only to water pressure but also to the suction force generated by the negative pressure inside the suction cup 2, making the fixation more stable.

[0048] For surfaces with a certain degree of curvature, such as ship hulls, the four legs of the worktable have spherical movable mechanisms where they connect to the suction cup fixing devices, such as... Figure 6 As shown, it allows for angle adjustment and rotation within a certain spatial range, and the spherical moving mechanism has a packing structure inside that increases resistance to maintain a stable state after being unaffected by external forces, thereby achieving the function of adsorbing onto curved surfaces.

[0049] After being fixed, the 3D laser scanner scans the target object and obtains point cloud data. By adjusting the position of the two rollers 18 connected to the sliding fixed seat 14 in the pulley groove 19 of the worktable, multiple sets of point cloud data of the same underwater target can be obtained, and then transmitted to the back-end computer on the water for a series of processing.

[0050] After the underwater scanning is completed, the spring 12 is reset by controlling the switch of the suction cup fixing device. At the same time, the piston rod 11 is moved towards the inlet of the negative pressure bottle 9 by the force, which balances the air pressure in the suction cup fixing device and discharges the water sucked up during fixing. Finally, the fixing is released.

[0051] like Figure 7 , Figure 8As shown, the inclined support leg of the underwater auxiliary fixing platform includes a first rod, a second rod, and a hydraulic telescopic rod 33. The upper end of the first rod is fixed to the top platform, and the lower end of the first rod is rotatably connected to the second rod. An inclined cone 32 is set at the bottom of the second rod. One end of the hydraulic telescopic rod 33 is connected to the first rod, and the other end is connected to the second rod.

[0052] For underwater object scanning in areas with sediment accumulation: Based on the fixed worktable, an auxiliary underwater platform can be installed first. This platform is secured by four angled cones 32 that penetrate the sediment. The angle of the linkage structure is adjusted by changing the length of the hydraulic telescopic rods 33 connected to the four mechanical limbs to achieve different heights. The instrument platform is then fixed to the auxiliary underwater platform using the suction cup 2 fixing device, after which the previous scanning operations can be performed.

[0053] An underwater auxiliary fixing platform is used in environments where suction cup fixing devices cannot reach the target object due to underwater silt. The suction cup fixing devices on the four legs of the workbench are fixed in the corresponding positions on the underwater auxiliary fixing platform, and then the four inclined cones 32 of the fixing platform are inserted into the silt surrounding the target object for fixation.

[0054] If there are seabed organisms attached to the surface of the target object to be scanned, the attachments can be removed by the multi-degree-of-freedom robotic arms 17 with waist joints 171 mounted on both sides of the platform after the platform device is fixed. After the removal is completed, the target object can be laser scanned.

[0055] like Figure 9 As shown, this invention uses a mounting platform with suction cups 2 to mount a 3D laser scanning device to scan underwater scenes, such as the underwater outer wall of a ship, bridge piers, and other structures or equipment that are not underwater and are inconvenient to fix for scanning. This allows the scanner to remain relatively stationary with the object without damaging it, thus obtaining accurate point cloud data. For underwater targets, such as mooring chains or underwater oil pipelines, in environments surrounded by silt and sand, a corresponding underwater auxiliary mounting platform is used to complete the scanning task.

[0056] The laser scanner emits a laser with a certain beamwidth from its laser port. At the same time, the scanner head can rotate at a certain angle. The laser is emitted from the emission port to the object being scanned, and then reflected by the object before being received by the sensors on the scanner to obtain the corresponding point cloud data.

[0057] Because of the underwater environment, the point cloud data obtained from scanning may have defects. Therefore, by moving the sliding mounting base 14 of the scanner device inside the worktable, multiple scans can be performed at different relative positions of the object being scanned, resulting in multiple sets of data. These multiple sets of data are then compared using software such as CloudCompare, and the high-quality point cloud data is selected for subsequent processing operations such as noise reduction and stitching.

[0058] like Figure 1 , Figure 3 As shown, a moving unit is provided inside the transparent sealing cover 21. The moving unit includes a sliding fixed seat 14, a rolling shaft, and rollers 18. The first robotic arm is a three-degree-of-freedom robotic arm 15, which is located at the bottom of the sliding fixed seat 14. The sliding fixed seat 14 is sleeved on the rolling shaft, and the rollers 18 are provided at both ends of the rolling shaft. The inner side of the left and right baffles 211 is provided with pulley grooves 19, and the rollers 18 are installed in the pulley grooves 19.

[0059] A transparent sealing cover 21, consisting of left and right baffles 211 and a transparent base plate 212, separates the laser scanner, the three-degree-of-freedom robotic arm 15 for clamping, and the soft robotic gripper from the water. Inside the transparent sealing cover 21, the base of the three-degree-of-freedom robotic arm 15 is fixed to a sliding fixed seat 14, which is connected to a rolling shaft. The scanner moves back and forth through the movement of the rolling shaft in the pulley groove 19, while the laser scanner moves left and right through the extension and retraction of the three-degree-of-freedom robotic arm 15. The laser scanner, clamped on the soft robotic gripper, emits a laser beam through the emitter in the laser emitter end 30, which then emits a planar beam through a lens at the internal port. The beam passes through the transparent base plate 212 and the water, illuminating the surface of the object being scanned, and then is reflected back through the water and the transparent base plate 212 to the receiving surface inside the reflected light receiver 31 (Figure AA).

[0060] By moving and adjusting the soft robotic arm 16, which carries a 3D laser scanner, within a certain space on the instrument platform, multiple sets of point cloud data of the same target area can be obtained. The obtained multiple sets of point cloud data are transmitted to the processing module on the water for preprocessing, registration, and stitching. Then, the processed and stitched 3D image is compared with the original image to ultimately achieve the purpose of measuring the damaged area.

[0061] Because laser scanning is performed underwater, in addition to considering the platform layout, the impact of laser refraction underwater on the point cloud data during transmission and reception must also be taken into account. Therefore, refraction correction is required for the obtained data. Figure 10As described above, the light plane A in the air is refracted through the glass surface to obtain the underwater light plane B. θ1 is the laser projection angle, θ2 is the angle between the light plane A and the normal C, θ3 is the angle between the normal A and the normal C, θ4 is the angle between the light plane B and the normal C, and θ5 is the angle between the normal B and the normal C.

[0062] Let the normal vector of the refracting surface be (0,0,1), the normal vector of the light plane A be (A,B,C), and the normal vector of the light plane B be (A',B',C'). The relative refractive index of water and air is n'. From the law of refraction, we can obtain:

[0063] n'=n1 / n3=sinθ1 / sinθ3=cosθ3 / cosθ5

[0064] Where n' is the relative refractive index of water and air, n1 is the relative refractive index of air and glass, n3 is the relative refractive index of glass and water, θ1 is the laser projection angle, θ3 is the angle between normal A and normal C, and θ5 is the angle between normal B and normal C.

[0065] The equation relating the normal vectors of light plane A and light plane B can be expressed as:

[0066]

[0067] Where (A,B,C) is the normal vector of light plane A, and (A',B',C') is the normal vector of light plane B.

[0068] Because the normal vector of the light plane B is:

[0069]

[0070] Where (A,B,C) is the normal vector of the light plane A.

[0071] Therefore:

[0072]

[0073] Where n' is the relative refractive index of water and air, (A,B,C) is the normal vector of light plane A, and (A',B',C') is the normal vector of light plane B.

[0074] According to the law of refraction, the normals to the incident light plane A, the refracted light plane B, and the refracted interface light plane C are coplanar. Therefore:

[0075]

[0076] Where (A,B,C) is the normal vector of light plane A, (A',B',C') is the normal vector of light plane B, and x and y are the undetermined coefficients of the equation.

[0077] Combining the above formulas, we can obtain:

[0078]

[0079] Where n' is the relative refractive index of water and air, (A,B,C) is the normal vector of light plane A, and (A',B',C') is the normal vector of light plane B.

[0080] The coordinates of the intersection point D of light plane A and light plane B with the glass surface are (0, Htanθ1, H), where H is the distance from the optical center of the camera to the glass surface. The equation of light plane B is:

[0081] A'x+B'y+C'z+D'=0

[0082] Where (A',B',C') is the normal vector of the light plane B, x, y, z represent the coordinates of the points on the plane in the spatial coordinate system, and D' represents the constant term in the equation.

[0083] Substituting the coordinates D into the equations of the light plane (the equations of the light plane A are: Ax + By + Cz + D = 0, and the aforementioned equation of the light plane B is A'x + B'y + C'z + D' = 0, where D in the equation of plane A is also a constant term), we get:

[0084]

[0085] Where (A,B,C) is the normal vector of the light plane A, (A',B',C') is the normal vector of the light plane B, (0,Htanθ1,H) are the coordinates of the intersection point D of the light plane A and the light plane B with the glass surface, and D and D' represent the constant terms in the equation.

[0086] In summary, the equation for the underwater laser plane after refraction can be obtained as follows:

[0087] A'x+B'y+C'z+D'=0

[0088] Where (A',B',C') is the normal vector of the light plane B, x, y, z represent the coordinates of the points on the plane in the spatial coordinate system, and D' represents the constant term in the equation.

[0089] Depend on Figure 10 It can be known that the target P in the water W The imaging point on the image plane is P(u,v). If it is in air, the image is directly formed at P'(u',v'). The relationship between P and P' is (u',v') = η(u,v). Therefore, for each measured point, only η needs to be obtained to achieve refraction correction.

[0090]

[0091] Where η is the proportionality coefficient when the planar coordinate values ​​of P and P' are equal, θ6 represents the angle between the reflected light from the glass into the air and the vertical plane, θ7 represents the angle between the reflected light from the light receiving surface and the vertical plane, θ8 represents the angle between the reflected light from the water into the glass and the vertical plane, G represents the intersection of the normal of the reflected light from the glass into the air and the horizontal plane where the scanned object point is located, E represents the intersection of the vertical line drawn downward from point P and the upper end of the glass surface, F represents the intersection of the vertical line drawn downward from point P and the horizontal plane where the scanned object point is located, I represents the intersection of the reflected light and the horizontal plane where the laser emitting end is located, J represents the intersection of the vertical line drawn downward from point P and the horizontal plane where the laser emitting end is located, and Oc is equivalent to point P for easy distinction and writing in the formula.

[0092] And because:

[0093]

[0094] O C J = f

[0095] Where I represents the intersection of the reflected light and the horizontal plane where the laser emitter is located, J represents the intersection of the perpendicular line drawn downward from point P and the horizontal plane where the laser emitter is located, Oc is equivalent to point P, and (u,v) represents the target P in the water. W The coordinates of the imaging point on the image plane, where f is the camera focal length, are in the Z... W >>When H (Zw represents the distance from the camera's light-receiving surface to the horizontal plane where the scanned object point is located), substituting the two equations into the above equation regarding η, we obtain the following formula for calculating η:

[0096]

[0097] Where η is the scaling factor when the planar coordinates of P and P' are equal, H is the distance from the optical center of the camera to the glass surface, (xc, yc, zc) are the coordinates of P' in the spatial coordinate system, Zc is the length of line segment OcF, θ8 represents the angle between the reflected light from the water into the glass and the vertical plane, θ6 represents the angle between the reflected light from the glass into the air and the vertical plane, and (u, v) represents the distance between the target P in the water and the vertical plane. W The coordinates of the imaging point on the image plane, where f is the camera focal length.

[0098] As can be seen from the above formula, the magnitude of θ8 has a certain influence on the calculation of η. The closer the value of tanθ8 is to a certain rational number, the more accurate the value of η will be. Therefore, the value of θ8 can be corrected to a certain extent by adjusting the angle of the transparent base plate of the transparent sealing cover. This invention designs a corresponding rotating base plate structure on the transparent sealing cover to achieve this purpose.

[0099] like Figure 11 , Figure 12As shown, the transparent base plate 212 is provided with a connector 24 and a driven gear 25. The connector 24 includes a fixing part and a rotating part. The fixing part is strip-shaped and embedded in the transparent base plate 212. The rotating part is cylindrical and rotatably connected to the front and rear baffles 213. The driven gear 25 is fixed on the transparent base plate 212. The front and rear baffles 213 are provided with a driving gear 26. The driving gear 26 meshes with the driven gear 25, thereby driving the transparent base plate 212 to rotate relative to the left and right baffles 211.

[0100] The left and right baffles 211 have deformable parts on their inner sides. The left and right ends of the transparent base plate 212 are arc-shaped surfaces. The arc-shaped surfaces of the transparent base plate 212 cooperate with and are sealed to the deformable parts of the left and right baffles 211. The bottom of the left and right baffles 211 also has inwardly protruding flanges.

[0101] Depend on Figure 11 As can be seen, the area where the left and right baffles 211 of the transparent sealing cover 21 connects to the transparent base plate 212 is designed with a certain curvature to facilitate the rotation of the base plate around the central axis. The ends of the left and right baffles 211 are provided with flanges and soft rubber is pasted on their surfaces to limit the degree of rotation of the transparent base plate 212, thereby achieving angle adjustment. At the same time, the four sides of the base plate are designed with a T-groove structure to embed polytetrafluoroethylene packing material to achieve dynamic sealing of the molded packing, thereby preventing water seepage during the process of rotating the base plate to adjust the angle.

[0102] The rotational motion of the transparent base plate 212 around its central axis is achieved through a gear-like component fixed to its end and a gear meshing mechanism. The fixing part of the connector 24 is inserted into the transparent base plate 212, and the rotating part is inserted into the front and rear baffles 213 of the transparent sealing cover 21. The front and rear ends of the transparent base plate 212 are rotatably connected to the front and rear baffles 213 through the rotating part. The driven gear 25 with a gear meshing structure is fixed to the transparent base plate 212 by bolts and meshes with the driving gear 26. Rotating the rotating shaft 29 drives the driving gear 26, which is fixed to the rotating shaft 29 by a key, to rotate. The gear meshing rotation drives the driven gear 25 and the transparent base plate 212 to rotate around the axis of the rotating part of the connector 24, thereby causing the transparent base plate 212 to rotate and tilt by a certain angle θ8 to adjust tanθ8 during scanning calculation to obtain the required value.

[0103] A stop 27 is provided in the rotating unit to restrict the axial movement of the rotating shaft 29 via the shoulder of the rotating shaft 29. At the same time, to consider the sealing problem of the rotating shaft 29 during rotation, a groove is provided on the front or rear baffle to fit a slip ring 28 made of polytetrafluoroethylene, and the slip ring 28 forms a rotational dynamic seal with the rotating shaft 29.

[0104] The rotation of the transparent base plate is achieved through a gear meshing rotation unit. The two meshing gears have the same module m but different numbers of teeth z. From the formula:

[0105]

[0106] Where n1 is the speed of the driving wheel, z1 is the number of teeth on the driving wheel, n2 is the speed of the driven wheel, z2 is the number of teeth on the driven wheel, and given time t, the speed n is:

[0107]

[0108] Where n is the rotational speed and t is the time taken for the gear to rotate by an angle θ. Combining the above two equations, we have:

[0109]

[0110] That is, the ratio of the rotation angles of two meshing gears is equal to the reciprocal of the ratio of their tooth numbers. By selecting driven and driving gears with different tooth ratios, the rotation angle of the transparent base plate can be adjusted simply and precisely.

[0111] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A three-dimensional laser scanning stage for measuring damaged areas of underwater objects, characterized in that, include: The instrument is equipped with a platform, a suction cup fixing device, and an underwater auxiliary fixing platform; The instrument is mounted on a platform with a transparent sealing cover and a support leg on the underside. The support leg is located around the transparent sealing cover. A first robotic arm is installed inside the sealing cover. The end of the first robotic arm is equipped with a robotic hand for holding the scanner. A second robotic arm for cleaning is installed on the support leg. The suction cup fixing device is installed on the underside of the support leg. The underwater auxiliary fixing platform includes a top platform and inclined legs. The suction cup fixing device can be attached to the top platform, and the bottom of the inclined legs is provided with an inclined cone that can be inserted into the silt. The upper opening of the transparent sealing cover includes left and right baffles, front and rear baffles and a transparent bottom plate. The upper ends of the left and right baffles and the front and rear baffles are sealed to the top plate of the instrument mounting platform, and the lower ends of the left and right baffles and the front and rear baffles are sealed to the transparent bottom plate. The left and right baffles, the front and rear baffles, the transparent bottom plate and the top plate of the instrument mounting platform form a sealed cavity for the scanner. The transparent base plate is provided with a connector and a driven gear. The connector includes a fixing part and a rotating part. The fixing part is strip-shaped and embedded in the transparent base plate. The rotating part is cylindrical and rotatably connected to the front and rear baffles. The driven gear is fixed on the transparent base plate. The front and rear baffles are provided with a driving gear. The driving gear meshes with the driven gear and drives the transparent base plate to rotate relative to the left and right baffles. The left and right baffles are provided with deformable parts on their inner sides. The left and right ends of the transparent base plate are arc-shaped surfaces. The arc-shaped surfaces of the transparent base plate cooperate with and are sealed to the deformable parts of the left and right baffles. The bottom of the left and right baffles also has inwardly protruding flanges.

2. The 3-D laser scanning platform for measuring damage area of an underwater object of claim 1, wherein, The transparent sealing cover is equipped with a moving unit, which includes a sliding fixed seat, a rolling shaft and rollers. The first robotic arm is a three-degree-of-freedom robotic arm and is located at the bottom of the sliding fixed seat. The sliding fixed seat is sleeved on the rolling shaft, and the rollers are provided at both ends of the rolling shaft. The inner sides of the left and right baffles are provided with pulley grooves, and the rollers are installed in the pulley grooves.

3. The 3-D laser scanning platform for underwater object damage area measurement of claim 1, wherein, The second robotic arm is a multi-degree-of-freedom robotic arm, which is mounted on the platform below the support legs of the instrument mounting platform via a waist joint rotation.

4. The 3-D laser scanning platform for underwater object damage area measurement of claim 1, wherein, The suction cup fixing device is connected to the support leg ball joint of the instrument mounting platform, and a filler layer is provided at the ball joint connection.

5. The 3-D laser scanning platform for underwater object damage area measurement of claim 1, wherein, The suction cup type fixing device includes a fixing sleeve, a suction cup, a connecting tube, and a negative pressure bottle. The fixing sleeve is fixed to the bottom of the support leg of the instrument mounting platform, the suction cup is set inside the fixing sleeve, and the negative pressure bottle is connected to the suction cup through the connecting tube.

6. The three-dimensional laser scanning platform for underwater object damage area measurement of claim 5, wherein, The negative pressure bottle is equipped with a piston push rod, which includes a piston and a rod end. The piston and the body of the negative pressure bottle are provided with a second sealing ring. A spring is sleeved on the rod end, with one end of the spring abutting against the piston and the other end abutting against the body of the negative pressure bottle.

7. The 3-D laser scanning platform for underwater object damage area measurement of claim 1, wherein, The inclined supporting leg of the underwater auxiliary fixing platform comprises a first rod, a second rod and a hydraulic telescopic rod, the upper end of the first rod is fixed with the top platform, the lower end of the first rod is rotationally connected with the second rod, an inclined tip cone is arranged at the bottom of the second rod, one end of the hydraulic telescopic rod is connected with the first rod, and the other end of the hydraulic telescopic rod is connected with the second rod.

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