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

Abstract

The present invention discloses a device and method for full-field three-dimensional scanning and detection of the inner wall of a pipeline. The present invention includes a laser tracking and measurement unit, which includes at least one laser tracker and multiple non-collinear target balls matched with the laser tracker; a motion control unit, which includes a ball screw linear module and a single-axis rotation module; a measuring 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 a control unit, which includes a computer, a measurement and control box, and a motor that drives the ball screw linear module and the single-axis rotation module. The present invention dynamically tracks the coordinates of the target ball through a laser tracker, combined with a line laser profile sensor and a rotation and translation motion stage, and can scan and obtain a full-field three-dimensional high-precision point cloud of the inner wall of a long straight pipe, significantly improving the dimensional detection accuracy and defect detection efficiency of the inner wall of the long straight pipe.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular 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, detecting defects (such as corrosion, deformation, or cracks) on the inner walls of long straight pipes is crucial to ensuring the safe operation of equipment. However, traditional methods (such as contact measurement) have significant limitations: low efficiency, detection blind spots, limited accuracy, and difficulty in achieving high-precision full-field three-dimensional reconstruction. Due to the long length of long straight pipes and the fact that a single scan can only cover a local area, multiple manual adjustments to the sensor posture are usually required, resulting in cumbersome operations and difficulty in ensuring the reliability of data fusion. Therefore, there is an urgent need for a full-field three-dimensional scanning method that can achieve automatic sensor posture tracking, real-time coordinate correction, and seamless point cloud stitching to significantly improve inspection efficiency and accuracy.

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

[0004] Chinese patent publication number CN119532562A discloses a pipeline inner wall inspection robot. Its core innovation lies in its adaptive topology adjustment capability: a hydraulic drive system controls the radial expansion of a movable frame, dynamically adjusting the distance between the drive wheels to accommodate pipes of varying diameters. Furthermore, a multi-jointed deformable structure overcomes the motion limitations of traditional inspection equipment in scenarios such as diameter changes and curves. The aforementioned prior art solutions suffer from the following drawbacks: the mechanical transmission system (synchronous belt / hydraulic cylinder / spring) is susceptible to wear, leakage, and fatigue failure, and the single-sided probe layout limits the inspection field of view, resulting in local blind spots.

[0005] The Chinese patent publication number CN110726731A discloses a device for detecting defects on the inner wall of a small-diameter, long straight tube. The core innovation lies in the use of a plane mirror to accurately transmit the light reflected from the tube wall to the industrial lens. By integrating the high-resolution, low-distortion characteristics of the telecentric mirror with the high-speed imaging technology of the linear array CCD camera, the detection accuracy is increased to 8μm while significantly reducing 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. Combined with the continuous scanning characteristics of the linear array CCD, a full-circumferential seamless splicing of the inner wall image can be quickly obtained in a single operation. The above-mentioned existing technical solutions have the following defects: the structure of the above-mentioned device is relatively complex and contains multiple precision components, such as plane mirrors, adjustable LED light sources, etc., which not only increases the manufacturing cost, but also puts higher demands on maintenance work. In addition, the device has high requirements for the detection environment and operating conditions. 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 faults when microcracks and holes coexist, which restricts the accuracy of defect detection.

[0006] The utility model with publication number CN208012553U discloses a cylinder inner wall detection system. By combining the structured light method with a telecentric lens, supplemented by pixel-level image analysis, it can achieve accurate quantitative calculation of the groove depth, greatly improving the detection accuracy. The non-contact detection method not only avoids damage to the surface of the object being measured, but also has the advantages of fast detection speed and the ability to continuously obtain three-dimensional data of the inner wall, which significantly improves the detection efficiency and data richness. The above-mentioned existing technical solutions have the following defects: the above-mentioned system places strict requirements on the accuracy of structured light projection and the control of the reflector angle, and periodic calibration is required to maintain detection reliability; environmental disturbances (such as stray light, mechanical vibration) can easily lead to a decrease in imaging quality, affecting detection accuracy; in addition, the system is highly dependent on high-precision optical components, and their replacement may trigger recalibration of the entire system, significantly increasing the complexity of operation and maintenance.

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

[0008] In view of the above-mentioned deficiencies in the prior art, the present invention provides a device and method for full-field three-dimensional scanning detection of the inner wall of a pipeline.

[0009] The present invention provides a device for full-field three-dimensional scanning and detection of the inner wall of a pipeline, comprising:

[0010] A laser tracking measurement unit, comprising at least one laser tracker and a plurality of non-collinear target spheres matched with the laser tracker;

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

[0012] A measuring unit, comprising a measuring rod connected to the single-axis rotating module and a line laser profile sensor fixed to one end of the measuring rod, wherein the line laser emitted by the line laser profile sensor is perpendicular to the pipeline axis;

[0013] A control unit, comprising a computer, a measurement and control box, and a motor for driving the ball screw linear module and the single-axis rotary module, wherein the computer is connected to the laser tracking measurement unit, the line laser profile sensor, and the measurement and control box;

[0014] 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 uses the above-mentioned device and 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 near end position of the pipeline;

[0017] Step 2. Use a laser tracker to measure the center coordinates of multiple non-collinear target spheres and establish a reference coordinate system;

[0018] Step 3. Obtaining point cloud data obtained by the first scanning of the line laser profile sensor at the near end 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 simultaneously control the ball screw linear module to move forward in a straight line and fix the single-axis rotation module, so that the line laser profile sensor moves along the inner wall of the pipe to the far end;

[0021] The point cloud data is acquired in real time and converted to the reference coordinate system. The ball screw linear module then retracts to the near end of the long straight tube, and the single-axis rotary module is controlled to rotate a fixed angle. If the preset number of rotations of the single-axis rotary module is not reached, the scanning process is repeated. Otherwise, the scanning process is terminated.

[0022] Step 6. Splice all converted point cloud data to generate complete 3D point cloud data of the inner wall of the pipeline.

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

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

[0025] 2. The detachable measuring rod, target base and other devices are suitable for complex industrial sites and can realize the rapid switching of long straight pipes of different specifications.

[0026] 3. The present invention can not only accurately detect the inner wall of a long straight pipe at a lower detection cost, thereby extending the service life of the long straight pipe, but also provide a high-precision three-dimensional data foundation for subsequent upgrades to integrated intelligent defect recognition algorithms.

[0027] 4. The detection device of the present invention has a simple structure, is easy to operate, and can also realize fully automated detection. It is suitable for scanning and detecting the inner walls of various long straight pipes and has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a general diagram of a long straight tube inner wall scanning and detection device provided by an example of the present invention;

[0029] Figure 2 This is a diagram showing the composition of a target ball and a flange in a long straight tube inner wall scanning and detection device provided by an example of the present invention;

[0030] Figure 3 This is a partial enlarged view of a device for scanning and detecting the inner wall of a long straight tube provided by an example of the present invention, which is composed of a ball screw, a single-axis rotation module flange, a target ball, a measuring rod, and a line laser profile sensor;

[0031] In the figure, 1. Laser tracker; 2. Laser tracker bracket; 3. Laser tracker controller; 4. Workbench No. 1; 5. Motor No. 1; 6. Ball screw; 7. Ball screw linear module; 8. Base; 9. Target ball 2; 10. Target ball 1; 11. Target ball 3; 12. Flange; 13. Single-axis rotation module; 14. Motor No. 2; 15. Measuring rod; 16. Line laser profile sensor; 17. Long straight pipe near end; 18. Long straight pipe far end; 19. Long straight pipe bracket; 20. Computer; 21. Workbench No. 2; 22. Measurement and control box. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

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

[0034] The laser tracking measurement unit includes at least one laser tracker 1, a laser tracker controller 3, and three non-collinear target balls (target ball 2 9, target ball 1 10, and target ball 3 11) matched with the laser tracker.

[0035] The motion control unit includes a ball screw linear module 7 (located on the No. 1 workbench 4) and a single-axis rotary module 13 (connected to the ball screw linear module 7 through the base 8). The single-axis rotary module is fixed on the slide of the ball screw linear module to form a two-dimensional motion table; the ball screw linear module and the single-axis rotary module are driven by the No. 1 motor 5 and the No. 2 motor 14 respectively; the two motors are respectively connected to the measurement and control box 22.

[0036] In some embodiments, motor No. 1 drives the ball screw 6 , which is threadedly connected to the base 8 .

[0037] The measuring unit includes a measuring rod 15 connected to the single-axis rotating module and a line laser profile sensor 16 fixed at one end of the measuring rod. The line laser profile sensor emits a line laser that is perpendicular to the axis of the long straight tube.

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

[0039] In some embodiments, in order to reduce the increase in the bending degree of the measuring rod as the measuring distance becomes longer, the material of the measuring rod is carbon fiber.

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

[0041] In some embodiments, the other side of the flange is fixed with the three SMR target balls supporting the laser trackers. The three SMR target balls supporting the laser trackers are not collinear; and the plane of the flange on which the SMR target balls supporting the three laser trackers are located is perpendicular to the direction of motion of the ball screw linear module.

[0042] The supporting structure includes a bracket for fixing the laser tracking measurement unit, the motion control unit and the measurement unit; the bracket includes a laser tracker bracket 2, a measuring rod bracket and a long straight tube bracket 19, and the bracket is used to fix the various components of the device and ensure its stability and accuracy.

[0043] A control unit includes a computer 20 (located on workbench No. 2 21), a measurement and control box, and a motor that drives 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 embodiment of the present application, the inner wall of the long straight tube is divided into N equal parts in the circumferential direction (the central angle of the arc corresponding to each equal part is recorded as θ), so that the line laser profile sensor rotates around the axis of the long straight tube N-1 times (each rotation angle is θ) inside the long straight tube. ), the line laser emitted by the line laser profile sensor can cover the entire circumference of a section of the inner wall of a long straight tube.

[0045] In this embodiment, the inner diameter of the long straight tube is 155 mm, the circumference of the inner wall is 489.4 mm, the length is 6 meters, and the rotation angle θ=5°, that is, N=72 times.

[0046] In a second aspect, an embodiment of the present application provides a full-field three-dimensional scanning detection method for the inner wall of a long straight pipe, the method steps are as follows:

[0047] Step 1: Use the computer to control the movement of the ball screw linear module, so that the line laser profile sensor moves to the near end of the long straight tube and stops, and the single-axis rotation module rotates the number of times ; Use the computer to control the laser tracker to measure the coordinates of the centers of target balls 1, 2 and 3 respectively ;in It refers to the first coordinate of the target ball obtained when the ball screw linear module moves from the near end of the long straight tube to the far end of the long straight tube. It 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 target ball one as the origin of the reference coordinate system and determine the X, Y, and Z axes.

[0049] Furthermore, the direction of the X-axis is from the center of target sphere 1 to the center of target sphere 2;

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

[0051]

[0052] Among them, in order to determine the XOY plane, the auxiliary vector is constructed based on the coordinates of the three centers of the target sphere:

[0053]

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

[0055]

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

[0057]

[0058] The Z axis is parallel to the measuring rod.

[0059] Step 3: The point cloud data obtained by the first scan of the laser profile sensor at the fire head near the port is recorded as ;in , represents the index of the point obtained in a single scan, The number of points obtained by the line laser profile sensor each time it scans.

[0060] Step 4: Convert the point cloud data measured by the line laser profile sensor into the reference coordinate system. The conversion formula is:

[0061]

[0062] in, , The 4×4 rigid body transformation matrix of the point cloud data measured by the line laser profile sensor when the single-axis rotation module is not moving during the first measurement is transferred to the reference coordinate system, that is:

[0063]

[0064] in, Euler angles The 3×3 rotation matrix is ​​determined by Refers to the rotation angle around the X, Y, and Z axes respectively. is the translation amount, Refers to the translation amount on the X, Y, and Z axes respectively. Refers to a rigid body transformation constructor;

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

[0066] 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 the target ball in real time. , ;in, Refers to the ball screw linear module moving from the long straight tube near the end to the long straight tube far end to obtain the first The coordinates of the target ball are also the coordinates of the line laser profile sensor. times scan; Refers to the ball screw linear module from the long straight tube near the end to the long straight tube far end, the line laser profile sensor scans a total of Second-rate.

[0067] The point cloud obtained by the line laser profile sensor is recorded as ; The point cloud data obtained by each line laser profile sensor can be transformed into All are transferred to the reference coordinate system;

[0068] Furthermore, the coordinate transformation matrix is:

[0069]

[0070] in, When the single-axis rotation module is not moving, the point cloud data measured by the line laser profile sensor for the kth time is transferred to the 4×4 rigid body transformation matrix of the reference coordinate system, that is:

[0071]

[0072] in, for point and point The distance between them.

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

[0074] The computer controls the fixed single-axis rotating module and controls the ball screw linear module to move forward in a straight line to prepare for the start of the first The first scan; After the first rotation, the laser profile sensor scans and obtains the When the laser tracker tracks the target ball, the coordinates are , the point cloud data obtained by the line laser profile sensor is recorded as ;

[0075] Then, the point cloud data measured by the line laser profile sensor is converted to point cloud data in the reference coordinate system. The conversion formula is:

[0076]

[0077] in, When the single-axis rotation module rotates i times, the point cloud data measured by the line laser profile sensor for the kth time is transferred to the 4×4 rigid body transformation matrix of the reference coordinate system, that is:

[0078]

[0079] in, It means that as the single-axis rotary module rotates, the rotation angle around the Z axis increases by θ. Then the computer controls the ball screw linear module to move backward linearly and return to the near end of the long straight tube. The number of rotations i is incremented by 1 and the next measurement is performed until N measurements are completed.

[0080] Step 6: Splice the point cloud data of each point in the reference coordinate system into a complete three-dimensional point cloud of the inner wall of the long straight pipe, and output the scanning results for the inner wall size calculation and defect analysis of the long straight pipe.

[0081] The above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, it may also include many other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for full-field three-dimensional scanning and detection of the inner wall of a pipeline, the device used includes: A laser tracking measurement unit, comprising at least one laser tracker and a plurality of non-collinear target spheres matched with the laser tracker; A motion control unit, comprising a ball screw linear module and a single-axis rotary module, wherein the single-axis rotary module is fixed on a slide of the ball screw linear module; A measuring unit comprising a measuring rod connected to the uniaxial rotating module and a line laser profile sensor fixed to one end of the measuring rod, wherein the line laser emitted by the line laser profile sensor is perpendicular to the pipeline axis; the other end of the measuring rod is fixed with the multiple non-collinear target balls via a flange; the plane of the flange is perpendicular to the movement direction of the ball screw linear module; A control unit, comprising a computer, a measurement and control box, and a motor for driving the ball screw linear module and the single-axis rotary module, wherein the computer is connected to the laser tracking measurement unit, the line laser profile sensor, and the measurement and control box; The length of the measuring rod is greater than the length of the pipeline to be inspected, 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; It is characterized in that it includes the following steps: Step 1. Control the ball screw linear module to move so that the line laser profile sensor moves to the near end position of the pipeline; Step 2. Use a laser tracker to measure the center coordinates of multiple non-collinear target spheres and establish a reference coordinate system; Step 3. Obtaining point cloud data obtained by the first scanning of the line laser profile sensor at the near end 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 simultaneously control the ball screw linear module to move forward in a straight line and fix the single-axis rotation module, so that the line laser profile sensor moves along the inner wall of the pipe to the far end; The point cloud data is acquired in real time and converted to the reference coordinate system through the rigid body transformation matrix. Then the ball screw linear module retreats to the near end of the long straight tube, and the single-axis rotation module is controlled to rotate a fixed angle. If the preset number of rotations of the single-axis rotation module is not reached, the scanning process is repeated. Otherwise, the scanning process is terminated. Step 6. Splice all converted point cloud data to generate complete 3D point cloud data of the inner wall of the pipeline.

2. The method according to claim 1, wherein: The establishment of the reference coordinate system described 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 Z-axis unit vector using the right-hand rule.

3. The method according to claim 1 or 2, wherein: In step 5, when the line laser profile sensor moves along the inner wall of the pipe to the distal end, the single-axis rotation module is fixed to allow the line laser profile sensor to scan a long strip area of ​​the inner wall of the pipe.

4. The method according to claim 3, wherein: In step 5, the line laser profile sensor rotates at the same angle each time to ensure the consistency and accuracy of the point cloud data.

5. The method according to claim 1, wherein In step 6, when all the converted point cloud data are spliced ​​together, a 3D reconstruction algorithm is used to generate complete 3D point cloud data of the inner wall of the pipeline.

6. The method according to claim 1, wherein The method further comprises the following steps after step 6: Post-processing the three-dimensional point cloud data to identify and analyze defects on the inner wall of the pipeline; Generate a test report based on the defect analysis results.

7. The method 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 multiple non-collinear target spheres.

8. The method according to claim 1 or 7, characterized in that The measuring rod is made of carbon fiber material to reduce bending and deformation during the measurement process.

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