Device and method for full-field three-dimensional scanning detection of inner wall of pipeline

Abstract

The invention discloses a device and a method for full-field three-dimensional scanning detection of an inner wall of a pipeline. The device comprises a laser tracking measurement unit, wherein the laser tracking measurement unit comprises at least one laser tracker and a plurality of non-collinear target balls matched with the laser tracker; the motion control unit comprises a ball screw linear module and a single-shaft rotating module; the measuring unit comprises a measuring rod connected with the single-axis rotating module and a line laser profile sensor fixed at one end of the measuring rod; and the control unit comprises a computer, a measurement and control box and a motor for driving the ball screw linear module and the single-shaft rotating module. According to the invention, the laser tracker dynamically tracks the coordinates of the target sphere, and the line laser contour sensor and the rotary translation motion platform are combined, so that the full-field three-dimensional high-precision point cloud of the inner wall of the long straight pipe can be scanned, and the size detection precision and defect detection efficiency of the inner wall of the long straight pipe are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and particularly to a device and method for full-field three-dimensional scanning detection of the inner wall of a pipeline. Background Art

[0002] In the field of industrial inspection, the detection of defects (such as corrosion, deformation or cracks) on the inner wall of long straight pipes is crucial for ensuring the safe operation of equipment. However, traditional methods (such as contact measurement) have significant limitations: low efficiency, detection blind spots, limited accuracy, and it is difficult to achieve high-precision full-field three-dimensional reconstruction. Due to the large length of long straight pipes and the fact that a single scan can only cover a local area, it is usually necessary to manually adjust the pose of the sensor multiple times, resulting in cumbersome operations and difficult to guarantee the reliability of data fusion. Therefore, there is an urgent need for a full-field three-dimensional scanning method that can achieve automatic tracking of the sensor pose, real-time coordinate correction and seamless stitching of point clouds, so as to significantly improve the detection efficiency and accuracy.

[0003] Although certain progress has been made in the current pipeline inner wall detection technology, there are still key technical bottlenecks.

[0004] Chinese Patent with publication number CN119532562A discloses a pipeline inner wall inspection robot. The core innovation lies in its adaptive topology adjustment ability: the hydraulic drive system is used to control the radial expansion of the movable frame and dynamically adjust the distance between the drive wheels, so as to adapt to pipelines with different diameters. At the same time, a multi-joint deformation structure is adopted to break through the motion limitations of traditional inspection equipment in scenarios such as variable diameter and bends. The above-mentioned prior art solutions have the following defects: the mechanical transmission system (synchronous belt / hydraulic cylinder / spring) in the above device is at risk of easy wear, leakage and fatigue failure, and the single-sided probe layout results in limited detection vision and local blind spots.

[0005] Chinese Patent with Publication No. CN110726731A discloses a device for detecting inner wall defects of small-diameter long straight pipes. The core innovation lies in using a plane mirror to accurately conduct the reflected light from the pipe wall to an industrial lens. By integrating the high-resolution and low-distortion characteristics of a telecentric lens with the high-speed imaging technology of a line array CCD camera, while improving the detection accuracy to 8μm, it significantly reduces image distortion. At the same time, the high-precision rotary table equipped with the equipment can drive the workpiece to achieve 360-degree axial rotation. Combining with the continuous scanning characteristics of the line array CCD, it can quickly obtain an inner wall image with seamless full circumferential stitching in a single operation. The existing technical solutions mentioned above have the following defects: The structure of the above device is relatively complex, including multiple precision components such as plane mirrors and adjustable LED light sources, which not only increases the manufacturing cost but also poses higher requirements for maintenance work. In addition, the device has high requirements for the detection environment and operating conditions, and it is necessary to ensure the high-precision operation of the rotary table and the stable connection and precise adjustment of each component. In particular, its V / U-shaped imaging hole is prone to image tomography in the scenario where microcracks and holes coexist, restricting the accuracy of defect detection.

[0006] The utility model with Publication No. CN208012553U discloses a cylindrical inner wall detection system. By combining structured light method with a telecentric lens and supplemented by pixel-level image analysis, it realizes precise quantitative calculation of the groove depth and greatly improves the detection accuracy. The non-contact detection method not only avoids damage to the surface of the object to be measured but also has advantages such as fast detection speed and the ability to continuously obtain three-dimensional data of the inner wall, significantly improving the detection efficiency and data richness. The existing technical solutions mentioned above have the following defects: The above system poses strict requirements on the projection accuracy of structured light and the control of the mirror angle, and periodic calibration is required to maintain the detection reliability; environmental disturbances (such as stray light and mechanical vibration) are likely to cause a decrease in imaging quality and affect the detection accuracy; in addition, the system highly depends on high-precision optical components, and their replacement may trigger a full-system recalibration, significantly increasing the operation and maintenance complexity.

[0007] Therefore, in view of the problems existing in the existing devices, such as small detection range, low detection accuracy, high equipment maintenance cost, and great implementation difficulty, a more comprehensive detection device and method with higher detection accuracy are needed to provide a reference for realizing full-dimensional and high-precision detection and analysis of the inner wall of long straight pipes. Summary of the Invention

[0008] The present invention aims at the above-mentioned deficiencies in the prior art and provides a device and method for full-field three-dimensional scanning detection of the inner wall of pipes.

[0009] A device for full-field three-dimensional scanning detection of the inner wall of pipes in the present invention includes:

[0010] A laser tracking measurement unit, which includes at least one laser tracker and a plurality of non - collinear target balls supporting the laser tracker;

[0011] A motion control unit, which includes a ball screw linear module and a single - axis rotation module, and the single - axis rotation module is fixed on the slide of the ball screw linear module;

[0012] A measurement unit, which includes a measuring rod connected to the single - axis rotation module and a line laser profile sensor fixed at one end of the measuring rod, and the line laser emitted by the line laser profile sensor is perpendicular to the pipeline axis;

[0013] A control unit, which includes a computer, a measurement and control box, and motors driving the ball screw linear module and the single - axis rotation module, and the computer is connected to the laser tracking measurement unit, the line laser profile sensor, and the measurement and control box;

[0014] Wherein, the length of the measuring rod is greater than the length of the pipeline to be detected, and the line laser profile sensor can rotate around the pipeline axis inside the pipeline to cover the entire circumference of a cross - section of the pipeline inner wall.

[0015] A full - field three - dimensional scanning detection method for the inner wall of a pipeline in the present invention, using the above - mentioned device, includes the following steps:

[0016] Step 1. Control the ball screw linear module to move so that the line laser profile sensor moves to the position of the near - end port of the pipeline;

[0017] Step 2. Measure the center coordinates of a plurality of non - collinear target balls by the laser tracker to establish a reference coordinate system;

[0018] Step 3. Obtain the point cloud data obtained by the first scan of the line laser profile sensor at the near - end port of the pipeline;

[0019] Step 4. Convert the point cloud data to the reference coordinate system;

[0020] Step 5. Control the laser tracker to track at least one target ball in real - time, and at the same time control the ball screw linear module to move forward linearly and fix the single - axis rotation module, so that the line laser profile sensor moves along the inner wall of the pipeline to the far - end port;

[0021] Obtain the point cloud data in real - time and convert it to the reference coordinate system, then the ball screw linear module retreats to the near - end port of the long straight pipe, control the single - axis rotation module to rotate a fixed angle, if the preset rotation times of the single - axis rotation module are not reached, then repeat the scanning process, otherwise, end the scanning process;

[0022] Step 6. Stitch all the converted point cloud data to generate the complete three-dimensional point cloud data of the inner wall of the pipeline.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. By dynamically tracking the coordinates of the target ball with a laser tracker, combining a line laser profile sensor and a rotary translation stage, the full-field three-dimensional high-precision point cloud of the inner wall of a long straight pipe can be scanned, significantly improving the detection accuracy of the inner wall dimensions of the long straight pipe and the detection efficiency of defects.

[0025] 2. Removable devices such as measuring rods and target seats can be applied to complex industrial sites and can achieve rapid switching of long straight pipes of different specifications, etc.

[0026] 3. The present invention can not only accurately detect the inner wall of a long straight pipe with relatively low detection costs, extend the service life of the long straight pipe, but also provide a high-precision three-dimensional data basis for subsequent upgrading to an integrated intelligent defect recognition algorithm.

[0027] 4. The detection device of the present invention has a simple structure, convenient operation, and can also achieve fully automated detection, is applicable to the scanning detection of the inner walls of various long straight pipes, and has a very broad application prospect. Description of the Drawings

[0028] Figure 1 is the overall drawing of a long straight pipe inner wall scanning detection device provided by an embodiment of the present invention;

[0029] Figure 2 is the composition drawing of the target ball and the flange in a long straight pipe inner wall scanning detection device provided by an embodiment of the present invention;

[0030] Figure 3 is the partial enlarged drawing of the device composed of a ball screw, a single-axis rotation module flange, a target ball, a measuring rod, and a line laser profile sensor in a long straight pipe inner wall scanning detection device provided by an embodiment of the present invention;

[0031] In the figure, 1. Laser tracker; 2. Laser tracker support; 3. Laser tracker controller; 4. First workbench; 5. First motor; 6. Ball screw; 7. Ball screw linear module; 8. Base; 9. Target ball two; 10. Target ball one; 11. Target ball three; 12. Flange; 13. Single-axis rotation module; 14. Second motor; 15. Measuring rod; 16. Line laser profile sensor; 17. Near port of the long straight pipe; 18. Far port of the long straight pipe; 19. Long straight pipe support; 20. Computer; 21. Second workbench; 22. Measurement and control box. Detailed Embodiments

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0033] As Figure 1 and Figure 2 shown, an embodiment of the present application provides a full-field three-dimensional scanning detection device for the inner wall of a long straight pipe, including:

[0034] A laser tracking measurement unit, which includes at least one laser tracker 1, a laser tracker controller 3, and three non-collinear target balls (specifically, target ball two 9; target ball one 10; target ball three 11) that are matched with the laser tracker.

[0035] A motion control unit, which includes a ball screw linear module 7 (located on the first workbench 4) and a single-axis rotation module 13 (connected to the ball screw linear module 7 through a base 8). The single-axis rotation module is fixed on the slide table of the ball screw linear module to form a two-dimensional motion stage; the ball screw linear module and the single-axis rotation module are respectively driven by a first motor 5 and a second motor 14; the two motors are respectively connected to a measurement and control box 22.

[0036] In some embodiments, the first motor drives a ball screw 6, and the ball screw 6 is threadedly connected to a base 8.

[0037] A measurement unit, which includes a measurement rod 15 connected to the single-axis rotation module and a line laser profile sensor 16 fixed at one end of the measurement rod. The line laser emitted by the line laser profile sensor is perpendicular to the axis of the long straight pipe.

[0038] As Figure 2 and Figure 3 shown, the single-axis rotation module fixed on the ball screw linear module is connected to one end of the measurement rod through one side of a flange 12; the other end of the measurement rod is fixed with the line laser profile sensor. The line laser emitted by the line laser profile sensor is perpendicular to the axis of the long straight pipe. The length of the measurement rod is greater than the length of the long straight pipe. During the measurement process, the line laser profile sensor gradually approaches the near port 17 of the long straight pipe and enters the long straight pipe and then moves towards the far port 18 of the long straight pipe.

[0039] In some embodiments, to reduce the increase in the bending degree of the measurement rod caused by the increase in the measurement distance, the material of the measurement rod is selected as carbon fiber material.

[0040] In some embodiments, the measurement rod is parallel to the moving direction of the ball screw linear module; the measurement rod is also parallel to the axis of the long straight pipe.

[0041] In some embodiments, SMR target balls that match the three laser trackers are fixed to the other side of the flange plate. Among them, the SMR target balls that match the three laser trackers are not collinear; the plane of the flange plate where the SMR target balls that match the three laser trackers are located is perpendicular to the moving direction of the ball screw linear module.

[0042] Support structure, the support structure includes brackets for fixing the laser tracking measurement unit, the motion control unit, and the measurement unit; the brackets include a laser tracker bracket 2, a measuring rod bracket, and a long straight pipe bracket 19, and the brackets are used to fix each component of the device and ensure its stability and accuracy.

[0043] Control unit, the control unit includes a computer 20 (located on the second workbench 21), a measurement and control box, and motors for driving the ball screw linear module and the single-axis rotation module. The computer is connected to the laser tracking measurement unit, the line laser profile sensor, and the measurement and control box.

[0044] In the embodiments of the present application, the circumferential direction of the inner wall of the long straight pipe is divided into N equal parts (the central angle corresponding to the arc of each equal part is denoted as θ), so that when the line laser profile sensor is inside the long straight pipe, after rotating N - 1 times around the axis of the long straight pipe (each rotation angle is θ, ) the line laser emitted by the line laser profile sensor can cover the entire circumference of a cross-section of the inner wall of the long straight pipe.

[0045] Among them, in this embodiment, the inner diameter of the long straight pipe is 155 mm, the inner wall circumferential perimeter is 489.4 mm, and the length is 6 meters. Taking the rotation angle θ = 5°, that is, N = 72 times.

[0046] In a second aspect, the embodiments of the present application provide a method for full-field three-dimensional scanning and detection of the inner wall of a long straight pipe. The steps of the method are as follows:

[0047] Step 1: Control the movement of the ball screw linear module through the computer, so that the line laser profile sensor moves to the near port of the long straight pipe and stops, and make the single-axis rotation module rotate a number of times ; Control the laser tracker through the computer to measure the coordinates of the centers of the first target ball, the second target ball, and the third target ball respectively ; Among them refers to obtaining the first coordinate of the first target ball when the ball screw linear module moves from the near port of the long straight pipe to the far port of the long straight pipe, and also refers to the first scan of the line laser profile sensor.

[0048] Step 2: Select the centers of the three target balls at this time to establish a reference coordinate system; select the center of the first target ball as the origin of the reference coordinate system and determine the X, Y, Z axes.

[0049] Furthermore, the direction of the X-axis is from the center of the first target ball to the center of the second target ball;

[0050] Then the unit vector of the X-axis is:

[0051]

[0052] Among them, to determine the XOY plane, the auxiliary vector constructed based on the center coordinates of the third target ball is:

[0053]

[0054] Then the unit vector of the Y-axis is:

[0055]

[0056] Among them, the unit vector of the Z-axis is determined by the right-hand rule, then the unit vector of the Z-axis is:

[0057]

[0058] Among them, the Z-axis is parallel to the measuring rod.

[0059] Step 3: Denote the point cloud data obtained from the first scan of the linear laser profile sensor at the near port of the fire length as ; where , represents the index of the points obtained in a single scan, is the number of points obtained by the linear laser profile sensor in each scan.

[0060] Step 4: By converting the point cloud data measured by the linear laser profile sensor to the reference coordinate system, its conversion formula is:

[0061]

[0062] Among them, , is the 4×4 rigid body transformation matrix for converting the point cloud data measured by the linear laser profile sensor to the reference coordinate system when the single-axis rotation module is not moving during the first measurement, that is:

[0063]

[0064] Among them, is the 3×3 rotation matrix determined by the Euler angles , respectively refer to the rotation angles around the X, Y, and Z axes, is the translation amount, respectively refer to the translation amounts on the X, Y, and Z axes, refers to a rigid body transformation constructor;

[0065] Step 5: The computer controls the laser tracker to always track Ball 1 among the three target balls; fix the single-axis rotation module and control the ball screw linear module to perform a linear forward movement, so that the line laser profile sensor moves to the far end of the long straight pipe; wherein, in this process, the line laser profile sensor scans to obtain a long strip area on the inner wall of the long straight pipe.

[0066] At the th scan section during the first measurement (i.e., when the single-axis rotation module is not started and the rotation angle is 0°), the laser tracker measures the coordinates of Ball 1 in real time as , ; wherein, refers to obtaining the coordinates of Ball 1 for the th time when the ball screw linear module moves from the near end of the long straight pipe to the far end of the long straight pipe, and also refers to the th scan of the line laser profile sensor; refers to the total number of scans of the line laser profile sensor when the ball screw linear module moves from the near end of the long straight pipe to the far end of the long straight pipe, which is times.

[0067] Record the point cloud obtained by the line laser profile sensor as ; through the coordinate transformation matrix, the point cloud data obtained by the line laser profile sensor each time can be transformed to the reference coordinate system;

[0068] Furthermore, the coordinate transformation matrix is:

[0069]

[0070] wherein, is a 4×4 rigid body transformation matrix for transforming the point cloud data measured by the line laser profile sensor for the kth time to the reference coordinate system when the single-axis rotation module does not move, that is:

[0071]

[0072] wherein, is the distance between point and point .

[0073] The computer controls the ball screw linear module to perform a linear backward movement to reach the near end of the long straight pipe; the computer controls the single-axis rotation module to make the line laser profile sensor rotate by an angle θ around the axis of the long straight pipe and stop.

[0074] The computer controls the fixed single-axis rotation module and controls the ball screw linear module to perform a linear forward movement to prepare for the The th scan; then after the th rotation, when the line laser profile sensor scans to obtain the th cross-section; the coordinates of the laser tracker tracking target ball 1 are , and the point cloud data obtained by the line laser profile sensor is denoted as

[0075] ; Then, the point cloud data measured by the line laser profile sensor is converted into the point cloud data in the reference coordinate system, and its conversion formula is:

[0076]

[0077] where, is the 4×4 rigid body transformation matrix for converting the point cloud data measured by the line laser profile sensor for the

[0078]

[0079] th time under the condition that the single-axis rotation module rotates i times to the reference coordinate system, that is: It means that as the single-axis rotation module rotates, the rotation angle around the Z-axis increases by θ successively. Then the computer controls the linear backward movement of the ball screw linear module to return to the near port of the long straight pipe, increments the rotation times i by 1, and performs the next measurement until N measurements are completed.

[0080] Step 6: Stitch the point cloud data of each time in the reference coordinate system into the complete three-dimensional point cloud of the inner wall of the long straight pipe, and output the scan result for calculating the inner wall size of the long straight pipe and defect analysis.

[0081] The above is only the preferred embodiment of the present invention and the applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A device for full-field three-dimensional scanning detection of the inner wall of a pipeline, characterized in that Including: A laser tracking measurement unit, which includes at least one laser tracker and a plurality of non - collinear target balls supporting the laser tracker; A motion control unit, which includes a ball screw linear module and a single - axis rotation module, and the single - axis rotation module is fixed on the slide table of the ball screw linear module; A measurement unit, which includes a measuring rod connected to the single - axis rotation module and a line laser profile sensor fixed at one end of the measuring rod, and the line laser emitted by the line laser profile sensor is perpendicular to the pipeline axis; A control unit, which includes a computer, a measurement and control box, and motors driving the ball screw linear module and the single - axis rotation module, and the computer is connected to the laser tracking measurement unit, the line laser profile sensor, and the measurement and control box; Wherein, the length of the measuring rod is greater than the length of the pipeline to be detected, and the line laser profile sensor can rotate around the pipeline axis inside the pipeline to cover the entire circumference of a cross - section of the pipeline inner wall.

2. The device for full-field three-dimensional scanning detection of the inner wall of a pipeline according to claim 1, characterized in that, There is at least one laser tracker, and each laser tracker can independently track at least one of the plurality of non - collinear target balls.

3. The device for full-field three-dimensional scanning detection of the inner wall of a pipeline according to claim 1 or 2, characterized in that, The measuring rod is made of carbon fiber material to reduce bending and deformation during measurement.

4. A full-field three-dimensional scanning detection method for the inner wall of a pipeline, using the device described in any one of claims 1 to 3, characterized in that, Including the following steps: Step 1. Control the movement of the ball screw linear module so that the line laser profile sensor moves to the position of the near - end port of the pipeline; Step 2. Measure the center coordinates of a plurality of non - collinear target balls by the laser tracker and establish a reference coordinate system; Step 3. Obtain the point cloud data obtained by the first scan of the line laser profile sensor at the near - end port of the pipeline; Step 4. Convert the point cloud data to the reference coordinate system; Step 5. Control the laser tracker to track at least one target ball in real time, and at the same time control the ball screw linear module to move straight forward and fix the single - axis rotation module, so that the line laser profile sensor moves along the inner wall of the pipeline to the far - end port; Obtain point cloud data in real time and convert it to the reference coordinate system, then the ball screw linear module retreats to the near - end port of the long straight pipe, control the single - axis rotation module to rotate a fixed angle, if the preset rotation times of the single - axis rotation module are not reached, repeat the scanning process, otherwise, end the scanning process; Step 6. Stitch all the converted point cloud data to generate the complete three - dimensional point cloud data of the pipeline inner wall.

5. The method according to claim 4, wherein: The establishment of the reference coordinate system in Step 2 further includes: Select the center of one of the target balls as the origin of the reference coordinate system; Determine the X, Y, and Z axes, where the Z axis is parallel to the measuring rod; Determine the unit vector of the Z axis through the right - hand rule.

6. The method according to claim 4 or 5, wherein, In Step 5, during the process of the line laser profile sensor moving along the inner wall of the pipeline to the far - end port, fix the single - axis rotation module to let the line laser profile sensor scan a long - strip area of the pipeline inner wall.

7. The method according to claim 6, wherein In Step 5, the rotation angle of the line laser profile sensor is equal each time to ensure the consistency and accuracy of the point cloud data.

8. The method according to claim 6, wherein In Step 5, converting the point cloud data obtained by each scan to the reference coordinate system includes using a coordinate transformation matrix for conversion.

9. The method according to claim 8, wherein, In step 6, when splicing all the converted point cloud data, a three-dimensional reconstruction algorithm is used to generate the complete three-dimensional point cloud data of the inner wall of the pipeline.

10. The method according to claim 4, wherein The method further includes steps carried out after step 6, namely: Performing post-processing on the three-dimensional point cloud data to identify and analyze the defects on the inner wall of the pipeline; Generating a detection report according to the defect analysis results.

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