Pipeline inner wall measuring system and pipeline inner wall measuring method

Abstract

The invention relates to the technical field of vision measurement, and provides a pipeline inner wall measuring system and a pipeline inner wall measuring method.The laser receiving target surface of the system is fixed to a measuring trolley, and the laser receiving target surface is perpendicular to the moving direction of the measuring trolley; the laser transmitter is used for transmitting laser rays to the laser receiving target surface, spots, falling on the laser receiving target surface, of the laser rays are not on the same straight line, and the laser rays are parallel to the movement direction of the measuring trolley; the annular laser is arranged on the measuring trolley and used for emitting annular laser to the inner wall of the pipeline; the camera is fixed on the measuring trolley and is used for shooting the annular laser; and the data processing terminal is used for calculating the pose of the measuring trolley and the local coordinates of the annular laser points, and is also used for reconstructing the three-dimensional shape of the inner wall of the pipeline according to the pose of the measuring trolley and the local coordinates of the annular laser points. According to the scheme, the inner wall of the pipeline can be measured with high precision when the walking mechanism is subjected to posture changes such as inclination and rotation.

Description

Technical Field

[0001] The present invention relates to the field of visual measurement technology, and in particular to a pipeline inner wall measurement system and a pipeline inner wall measurement method. Background Art

[0002] With the progress and development of science and technology, pipelines are widely used in various fields, such as petroleum and chemical industries. During the use of pipelines, pits, bulges, structural damage or straightness deformation of the entire pipeline may appear on the inner wall, so it is necessary to regularly inspect the inner wall of the pipeline.

[0003] One existing pipeline measurement method is to use only a single camera to capture images of the inner wall of the pipeline and detect pipeline defects through image processing. The disadvantage of this method is that the images are two-dimensional plane images one by one, lacking three-dimensional information, and cannot accurately construct a three-dimensional model of the inner wall of the pipeline.

[0004] Another existing pipeline measurement method is to use a camera and a ring laser to form a triangulation measurement to measure the inner wall of the pipeline. This method can indeed accurately measure a section of the pipeline if the camera is not moving, but when the camera moves along the pipeline, the camera posture may change due to the tilt, rotation and other posture changes of the walking mechanism equipped with the camera, which will lead to errors in the reconstruction of the entire pipeline.

[0005] The Chinese patent publication number CN107063119A discloses a device and method for measuring the inner wall morphology and central axis straightness of a pipe. The patent decomposes posture changes, such as translation, pitch, yaw, and roll, and solves for each type. However, the actual posture of the target may have both translation and pitch, or both roll and yaw. When the target is not in a special posture, the patent cannot cope with it. The patent wants to calculate the posture of the laser probe by receiving the two-dimensional coordinates on the laser target, but the two-dimensional coordinates and the posture are not one-to-one corresponding, such as Figure 1 As shown in the figure, one two-dimensional coordinate may correspond to multiple postures. Therefore, the posture calculated by this method may be wrong. A specific example is as follows: if two planes are mirror-symmetric in the vertical direction, the two-dimensional coordinates of the light spots on the two planes in the plane coordinate system are the same, so it is impossible to calculate a unique posture only through the two-dimensional coordinates on the plane.

[0006] Therefore, it is necessary to provide a pipeline inner wall measurement system and a pipeline inner wall measurement method, which can measure the pipeline inner wall with high precision when the walking mechanism undergoes posture changes such as tilting and rotation.

[0007] The above information disclosed in the Background section is only for enhancement of understanding of the background of the present application and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0008] The main purpose of the present invention is to overcome the problem of being unable to obtain high-precision measurement results of the inner wall of a pipeline, and to provide a pipeline inner wall measurement system and a pipeline inner wall measurement method, which can measure the inner wall of the pipeline with high precision when the walking mechanism undergoes posture changes such as tilting and rotation.

[0009] To achieve the above-mentioned purpose, the first aspect of the present invention provides a pipeline inner wall measurement system, comprising: a measurement trolley, a ring laser, a camera, at least three laser transmitters, a laser receiving target surface and a data processing terminal;

[0010] The measuring trolley is used to travel inside the pipeline;

[0011] The laser receiving target surface is fixed on the measuring trolley, and the laser receiving target surface is perpendicular to the moving direction of the measuring trolley;

[0012] At least three laser transmitters are used to emit laser lines to the laser receiving target surface, the spots where at least three laser lines fall on the laser receiving target surface are not on the same straight line, and the laser lines are parallel to the moving direction of the measuring vehicle;

[0013] The ring laser is arranged on the measuring trolley and is used to emit the ring laser to the inner wall of the pipeline;

[0014] The camera is fixed on the measuring trolley and is used to shoot the ring laser;

[0015] The data processing terminal is communicatively connected with the laser receiving target surface, the laser transmitter and the camera, and is used to calculate the position and posture of the measuring vehicle and the local coordinates of the annular laser point, and is also used to reconstruct the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point.

[0016] As an exemplary embodiment of the present invention, the pipeline inner wall measurement system further includes a synchronization controller, which is connected to the laser generator, the laser receiving target surface, the camera, and the ring laser.

[0017] As an example embodiment of the present invention, the laser receiving target surface is arranged at the rear of the measuring trolley, the laser transmitter is arranged behind the measuring trolley, the laser receiving target surface includes a relative receiving surface and an opposite surface, the receiving surface receives the laser line, and the opposite surface is fixedly connected to the camera.

[0018] As an exemplary embodiment of the present invention, the camera shoots in the front of the measuring vehicle.

[0019] As a second aspect of the present invention, the present invention provides a pipeline inner wall measurement method, using the pipeline inner wall measurement system, comprising the following steps:

[0020] S1: Before the measurement begins, calibrate the relative position relationship between the camera and the ring laser;

[0021] S2: At the beginning of measurement, push the measuring trolley into the initial position of the pipeline inlet;

[0022] S3: During measurement, the measuring trolley moves forward to obtain the coordinates of the spot on the laser receiving target surface and the flight time of the laser, while the camera shoots the ring laser;

[0023] S4: The position and posture of the measuring vehicle are obtained according to the coordinates of the spot in the laser receiving target surface and the flight time of the laser, and the local coordinates of the annular laser point are obtained according to the annular laser captured by the camera;

[0024] S5: Reconstruct the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point.

[0025] As an exemplary embodiment of the present invention, the pipeline inner wall measurement method further includes: S6: calculating the pipeline straightness.

[0026] As an exemplary embodiment of the present invention, step S2 further includes: turning on the laser transmitter, and recording the spot position received by the laser receiving target surface and the flight time of the laser.

[0027] As an exemplary embodiment of the present invention, in step S4, obtaining the position and posture of the measuring vehicle according to the coordinates of the spot in the laser receiving target surface and the flight time of the laser includes:

[0028] S411: establishing a target plane coordinate system and a laser coordinate system, wherein the target plane coordinate system includes an initial state target plane coordinate system and a moving state target plane coordinate system;

[0029] S412: Calculating the transformation relationship between the laser coordinate system and the initial state target plane coordinate system according to the flight time of the initial state laser and the coordinates of the initial state spot on the laser receiving target surface;

[0030] S413: Calculating the transformation relationship between the laser coordinate system and the initial state target plane coordinate system according to the flight time of the moving state laser and the coordinates of the moving state spot on the laser receiving target surface;

[0031] S414: Calculate the transformation relationship between the initial state target plane coordinate system and the moving state target plane coordinate system according to the above two transformation relationships to obtain the position and posture of the measuring vehicle.

[0032] As an exemplary embodiment of the present invention, in step S4, obtaining the local coordinates of the annular laser point according to the annular laser captured by the camera includes:

[0033] S421: performing sub-pixel extraction on the ring laser in the image to obtain the center position of the laser point;

[0034] S422: According to the relative position relationship between the camera and the ring laser, the local coordinates of the ring laser point on the pipeline are calculated using triangulation.

[0035] As an exemplary embodiment of the present invention, in step S5, reconstructing the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point includes:

[0036] According to the position and posture of the measuring vehicle, the local coordinates of the annular laser point are converted into global coordinates to obtain the inner wall shape of the pipeline after three-dimensional reconstruction.

[0037] The advantages of the present invention are:

[0038] This solution only uses three laser transmitters and one laser receiving target plane. With a simple calculation method, the position and posture of the measuring trolley can be obtained in real time when measuring the pipeline. When reconstructing the pipeline, the position and posture of the measuring trolley and the ring laser captured by the camera are combined to obtain a more accurate three-dimensional image of the inner wall of the pipeline. Accurate measurement and reconstruction can also be performed when the measuring trolley rotates or is eccentric. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other objects, features and advantages of the present application will become more apparent by describing in detail the exemplary embodiments thereof with reference to the accompanying drawings. The accompanying drawings described below are only some embodiments of the present application, and it is clear to a person skilled in the art that other accompanying drawings can be obtained from these accompanying drawings without creative effort.

[0040] Figure 1 The schematic diagram of the calculation process of the background technology patent is shown schematically.

[0041] Figure 2 The schematic diagram of the pipeline inner wall measurement system is shown schematically.

[0042] Figure 3 The relationship between the spot and the laser receiving target surface is schematically shown.

[0043] Figure 4 The diagram schematically shows the steps of the pipeline inner wall detection method.

[0044] Figure 5 The steps of measuring the position and posture of the vehicle are schematically shown.

[0045] Figure 6 A schematic diagram of the coordinate system is schematically shown.

[0046] Figure 7 The schematic diagram shows the principle diagram of pipeline inner wall profile measurement.

[0047] Figure 8 The schematic diagram shows the principle diagram for calculating pipeline straightness.

[0048] Among them, 1 is a data processing terminal, 2 is a synchronization controller, 3 is a data connection line, 4 is a laser transmitter, 5 is a laser line, 6 is a laser receiving target surface, 7 is a camera, 8 is a ring laser, 9 is a measuring trolley, 10 is a pipeline, and 11 is a ring laser. DETAILED DESCRIPTION

[0049] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0050] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0051] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0052] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0053] It should be understood that although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0054] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0055] According to a first specific embodiment of the present invention, the present invention provides a pipeline inner wall measurement system, such as Figure 2 As shown, it includes: a measuring vehicle 9, a ring laser 11, a camera 7, at least three laser transmitters 4, a laser receiving target surface 6, a data processing terminal 1, a data connection line 3 and a synchronization controller 2.

[0056] The measuring trolley 9 is used to travel in the pipeline 10. The measuring trolley 9 is a carrying platform for the pipeline inner wall measuring devices. It is necessary to ensure that each device is installed as required and provide the power supply and optical path conditions required for the normal operation of each device. At the same time, a stable driving module composed of multiple micro motors and rollers is installed in the measuring trolley 9 to provide stable travel in the pipeline 10.

[0057] The laser receiving target surface 6 is fixed on the measuring trolley 9, and the laser receiving target surface 6 is perpendicular to the moving direction of the measuring trolley 9. Since the laser receiving target surface 6 is fixedly connected to the measuring trolley 9, the position and posture of the laser receiving target surface 6 is the position and posture of the measuring trolley 9.

[0058] At least three laser emitters 4 are used to emit parallel laser lines to the laser receiving target surface, such as Figure 3 As shown, the spots of at least three laser lines 4 falling on the laser receiving target surface 6 are not in the same straight line, and the laser lines 4 are parallel to the moving direction of the measuring vehicle 9. In order to obtain the position and posture of the measuring vehicle 9, the number of laser lines 4 used can be greater than or equal to 3. As a preferred embodiment, Figure 3 As shown, there are three laser emitters 4, which are three vertices of an isosceles right triangle or an equilateral triangle. The laser emitters 4 are highly collimated lasers.

[0059] The synchronous controller 2 is connected to the data processing terminal 1, the laser generator 4, the laser receiving target surface 6, the camera 7, and the ring laser 11 through the data connection line 3. The synchronous controller 2 will generate a pulse signal of a fixed frequency to control the synchronous triggering of the equipment (laser generator 4, laser receiving target surface 6, camera 7, ring laser 11). In this scheme, it is necessary to obtain the position and posture of the camera 7 at the same time and the image taken by the camera 7 at the same time. The camera 7 takes images frame by frame, and the ring laser 11 and the laser transmitter 4 also emit lasers synchronously.

[0060] Ring laser 11( Figure 2 Not shown, see Figure 7 The measuring device (schematically shown) is arranged on the measuring trolley 9 and is used to emit a ring laser toward the inner wall of the pipeline 10.

[0061] The camera 7 is fixed on the measuring carriage 9 and is used to photograph the ring laser. The camera is a high-resolution camera.

[0062] like Figure 2 As shown, the laser receiving target surface 6 is arranged at the rear of the measuring trolley 9, and the laser transmitter 4 is arranged at the back of the measuring trolley 9. The laser receiving target surface 6 includes a relative receiving surface and an opposite surface. The receiving surface faces the rear of the measuring trolley 9 and receives the laser line 5, and the opposite surface is fixedly connected to the camera 7. The camera 7 shoots in front of the measuring trolley 9. The front part of the measuring trolley 9 is a pipeline profile measurement module (camera 7 and ring laser 11), and the rear part is a posture measurement module of the measuring trolley 9 (laser receiving target surface 6 and laser transmitter 4). The two modules are installed back to back, which can greatly reduce the size of the entire measuring device, so that the system can be applied to slender pipelines.

[0063] The data processing terminal 1 is communicatively connected to the laser receiving target surface 6, the laser transmitter 4 and the camera 7, and is used to calculate the position and posture of the measuring trolley 9 and the local coordinates of the annular laser point, and is also used to reconstruct the three-dimensional shape of the inner wall of the pipeline 10 based on the position and posture of the measuring trolley 9 and the local coordinates of the annular laser point.

[0064] According to a first specific embodiment of the present invention, the present invention provides a pipeline inner wall measurement method, using the pipeline inner wall measurement system of the first specific embodiment, such as Figure 4 As shown, the following steps are included:

[0065] S1: Before the measurement starts, the relative position relationship between the camera 7 and the ring laser 11 is calibrated.

[0066] S2: When the measurement starts, the measuring trolley 9 is pushed into the initial position of the entrance of the pipeline 10.

[0067] After the measuring trolley 9 reaches the initial position, the laser transmitter is turned on to record the spot position received by the laser receiving target surface 6 and the flight time of the laser.

[0068] The flight time of the laser refers to the time it takes for the laser to be emitted from the laser transmitter 4 to reach the laser receiving target surface 6. Based on the flight time of the laser, the distance from the emission to the reception of the laser can be known.

[0069] S3: During measurement, the measuring trolley moves forward to obtain the coordinates of the spot on the laser receiving target surface and the flight time of the laser, while the camera shoots the ring laser.

[0070] The measuring trolley 9 is constantly moving, and the position and posture of the measuring trolley 9 can be calculated once each time data is acquired, so the position and posture of the measuring trolley 9 can be calculated in real time.

[0071] S4: The position and posture of the measuring vehicle 9 is obtained according to the coordinates of the spot in the laser receiving target surface 6 and the flight time of the laser, and the local coordinates of the annular laser point are obtained according to the annular laser captured by the camera 7.

[0072] like Figure 5 As shown, the position and posture of the measuring vehicle 9 are obtained according to the coordinates of the spot in the laser receiving target surface and the flight time of the laser, including:

[0073] S411: Establish a target plane coordinate system and a laser coordinate system, wherein the target plane coordinate system includes an initial state target plane coordinate system and a moving state target plane coordinate system.

[0074] like Figure 6 As shown, the laser coordinate system is a coordinate system established with the laser emitter 4 as the reference. The laser emitter 4 is immobile, so the laser coordinate system is fixed from the initial state to the moving state. However, since the measuring trolley 9 is always moving in six degrees of freedom, it drives the laser receiving target surface 6 to move. The target plane coordinate system is a coordinate system established with the laser receiving target surface 6 as the reference. Since the laser receiving target surface 6 is moving, the target plane coordinate system is moving from the initial state to the moving state and is not fixed.

[0075] Figure 6 In the figure, the laser coordinate system includes X-axis, Y-axis and Z-axis, wherein the Z-axis is parallel to the direction of the laser line 5. The black far point represents the laser emitter 4. Since the laser emitter 4 is fixed, the coordinates of the X-axis and Y-axis of the laser emitter remain unchanged. However, since the measuring trolley 9 moves, the distance from the laser emitter 4 to the laser receiving target surface 6 changes, so the coordinate of the Z-axis changes. Figure 6 Points A, B, and C represent the three spots in the initial state, and points A', B', and C' represent the spots corresponding to points A, B, and C in the moving state.

[0076] S42: Calculate the transformation relationship between the laser coordinate system and the initial state target plane coordinate system according to the flight time of the initial state laser and the coordinates of the initial state spot on the laser receiving target surface.

[0077] Assume that the three points on the laser receiving target surface 6 are A, B, and C, and their coordinates in the target plane coordinate system are (x1, y1, 0), (x2, y2, 0), and (x3, y3, 0). In the laser coordinate system, the coordinates of the three points are (X1, Y1, Z1), (X2, Y2, Z2), and (X3, Y3, Z3).

[0078] In the laser coordinate system, since the three laser emitters 4 are fixed, the X and Y coordinates of the three spots in the laser coordinate system are fixed, and the only variable is the Z coordinate, that is, the distance from the spot to the laser emitter 4. The X and Y coordinates are determined by the placement of the laser emitter 4. For example, if the three laser emitters 4 are the three vertices of an equilateral triangle with a side length of a, then the coordinates of the three points in the laser coordinate system are (0,0,Z1), (a,0,Z2), If the three laser emitters 4 are an isosceles right triangle with a side length of a, then the coordinates of the three points in the laser coordinate system are (0, 0, Z1), (a, 0, Z2), and (0, a, Z3).

[0080] According to the flight time of the initial state laser and the coordinates of the initial state spot on the laser receiving target surface, the transformation relationship between the laser coordinate system and the initial state target plane coordinate system is calculated by combining the following equations:

[0081]

[0082] Wherein, M1 is the transformation matrix from the laser coordinate system to the initial state target plane coordinate system, R1 is the initial state rotation matrix, T1 is the initial state translation vector; (x, y, z) is the coordinate of a spot in the initial state on the target plane coordinate system; (X, Y, Z) represents the coordinate of the spot in the laser coordinate system;

[0083] There are three spots in the initial state. The three equations are combined to obtain the transformation matrix from the laser coordinate system to the initial state target plane coordinate system.

[0084] The Z coordinate in the initial state laser coordinate system is obtained by calculating the distance from the laser emitter 4 to the laser receiving target surface 6 according to the flight time of the initial state laser.

[0085] S43: Calculate the transformation relationship between the laser coordinate system and the motion state target plane coordinate system according to the flight time of the motion state laser and the coordinates of the motion state spot on the laser receiving target surface.

[0086] In the moving state, the three spots form three new points on the laser receiving target surface 6. The coordinates of A', B', and C' on the target plane coordinate system are updated to (x1', y1', 0), (x2', y2', 0), and (x3', y3', 0). The distances from the three spots to the laser emitter 4 are updated. In the case of an equilateral triangle, the coordinates of the three spots on the laser coordinate system are (0, 0, Z1'), (a, 0, Z2'), Substitute the new coordinates into the transformation formula for calculation.

[0087] According to the flight time of the moving laser and the coordinates of the moving spot on the laser receiving target surface, the transformation relationship between the laser coordinate system and the moving target plane coordinate system is calculated by combining the following equations:

[0088]

[0089] Wherein, M2 is the transformation matrix from the laser coordinate system to the target plane coordinate system in motion state, R2 is the rotation matrix of motion state, T2 is the translation vector of motion state; (x', y', z') is the coordinate of a spot in motion state on the target plane coordinate system; (X, Y, Z) represents the coordinate of the spot in the laser coordinate system;

[0090] There are three spots in motion state. The three equations are combined to obtain the transformation matrix from the laser coordinate system to the motion state target plane coordinate system.

[0091] The X coordinate and Y coordinate of the spot in the initial state in the laser coordinate system are respectively equal to the X coordinate and Y coordinate of the spot in the moving state in the laser coordinate system.

[0092] The Z coordinate in the motion state laser coordinate system is obtained by calculating the distance from the laser transmitter 4 to the laser receiving target surface 6 according to the flight time of the motion state laser.

[0093] S44: Calculate the transformation relationship between the initial state target plane coordinate system and the moving state target plane coordinate system according to the above two transformation relationships to obtain the position and posture of the measuring vehicle 9.

[0094] According to the above two transformation relationships, the transformation relationship between the initial state target plane coordinate system and the moving state target plane coordinate system is calculated, and the position and posture of the measuring vehicle 9 are obtained, including:

[0095] Combining the above two transformation equations, we can get:

[0096]

[0097] The real-time rotation matrix and the real-time translation vector are obtained according to the following equations, that is, the motion displacement of the measuring vehicle 9 relative to the initial state is obtained:

[0098]

[0099] Among them, (x', y', z') is the coordinate of a spot in the moving state on the target plane coordinate system; (x, y, z) is the coordinate of the spot in the initial state on the target plane coordinate system; M is the coordinate transformation matrix, M = M2 × M1- 1 , R is the real-time rotation matrix, T is the real-time translation vector;

[0100] The position and posture of the measuring trolley 9 are obtained according to the initial position of the measuring trolley 9 and the movement displacement of the measuring trolley 9 relative to the initial state.

[0101] First, the coordinate transformation matrix R and T are calculated, and then decomposed into angles in three directions and displacements in three directions, to obtain a total of 6 degrees of freedom information, plus the three-dimensional spatial information of the distance from the light spot to the laser emitter, which solves the problem that the patent CN107063119A cannot calculate a unique posture. At the same time, this application uses a parallel laser emitter with a laser receiving target to obtain the three-dimensional global coordinates of the target, which is simpler and more economical, and does not require a complex and expensive laser tracker.

[0102] The position and posture measurement principle of the measuring vehicle 9:

[0103] Three lasers are fixed at the pipe port, and the three laser beams are parallel to each other, providing three laser reference lines as the reference for the straightness of the pipe. Then, the laser receiving target surface 6 placed on the measuring trolley 9 is an imaging sensor. The measuring trolley 9 receives three laser beams of irradiation during its movement in the pipe 10. The eccentricity, deflection, and rotation of the measuring trolley 9 are measured according to the positions of the three laser light plates. The flight time of the laser is obtained according to the laser transmitter 4, and then the moving distance of the measuring trolley 9 is obtained, thereby realizing high-precision and rapid measurement of the six-degree-of-freedom of the measuring trolley 9.

[0104] The local coordinates of the ring laser point obtained based on the ring laser captured by the camera include:

[0105] S421: Perform sub-pixel extraction on the ring laser in the image to obtain the center position of the laser point.

[0106] The ring laser is a ring-shaped laser line, which is composed of multiple laser points. Knowing the center position of each laser point, a ring-shaped laser line can be formed, corresponding to a section of the inner wall of the pipe 10.

[0107] S422: According to the positional relationship between the camera 7 and the ring laser 11, the local coordinates of the ring laser point on the pipeline 10 are calculated using triangulation.

[0108] Principle of pipeline inner wall profile measurement:

[0109] like Figure 7As shown, the ring laser 11 and the camera 7 are installed facing each other on the measuring trolley 9. On the measuring trolley 9, the ring laser 11 generates a ring laser line which is projected onto the inner wall surface of the pipe 10 through an optical light-transmitting window specially provided on the fixed structure, and the camera 7 images the ring laser line through the specially provided optical light-transmitting window. The imaging ray direction of a certain point on the ring laser line in three-dimensional space can be determined by the camera 7. The laser line projection generated by the ring laser can determine that the point of the ring laser line on the inner wall of the pipe 10 is located on a certain plane in three-dimensional space. By measuring the intersection of the line and the plane in three-dimensional space, the position coordinates of any point of the laser line projected on the inner wall of the pipe 10 in three-dimensional space can be obtained.

[0110] S5: Reconstruct the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point.

[0111] Reconstructing the three-dimensional shape of the inner wall of the pipeline 10 according to the position and posture of the measuring vehicle 9 and the local coordinates of the annular laser point includes:

[0112] According to the position and posture of the measuring vehicle 9, the local coordinates of the annular laser point are converted into global coordinates to obtain the inner wall shape of the pipeline 10 after three-dimensional reconstruction.

[0113] The local coordinates refer to the coordinates of the pipe section illuminated by the annular laser in the current camera coordinate system, and the global coordinate system refers to the coordinates of the pipe section illuminated by the annular laser in the initial camera coordinate system before the measurement begins.

[0114] S6: Calculate pipeline straightness.

[0115] Straightness calculation method: After the pipeline coordinates are unified into the global coordinate system, that is, after the three-dimensional reconstruction is completed, Figure 8 As shown, calculate the coordinates of the centers of the two ends of the pipeline (the centers of the pipeline sections at both ends) respectively, connect the two center points with a straight line, and obtain the reference axis of the pipeline ( Figure 8 Then calculate the center of each section of the pipeline and the distance from the center point to the reference axis. Take the maximum value d of the distance from the center of all sections to the reference axis, which is the straightness of the pipeline.

[0116] Function: By calculating the straightness of the pipeline, it can be determined whether the pipeline is bent. If the straightness of the pipeline is large, it means that the pipeline is severely bent and deformed, and the pipeline needs to be repaired or replaced.

[0117] This solution only uses three laser transmitters 4 and one laser receiving target plane 6. With a simple calculation method, the position and posture of the measuring trolley 9 itself can be obtained in real time when measuring the pipeline 10. When reconstructing the pipeline 10, the position and posture of the measuring trolley 9 and the ring laser captured by the camera 7 are combined, and the three-dimensional shape of the inner wall of the pipeline 10 is obtained with higher accuracy. When the measuring trolley 9 rotates and is eccentric, accurate measurement and reconstruction can also be performed.

[0118] The exemplary embodiments of the present invention are specifically shown and described above. It should be understood that the present invention is not limited to the detailed structure, configuration or implementation method described herein; on the contrary, the present invention is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A pipeline inner wall measurement system, characterized in that: include: Measuring trolley, ring laser, camera, at least three laser transmitters, laser receiving target surface and data processing terminal; The measuring trolley is used to travel inside the pipeline; The laser receiving target surface is fixed on the measuring trolley, and the laser receiving target surface is perpendicular to the moving direction of the measuring trolley; At least three laser transmitters are used to emit laser lines to the laser receiving target surface, the spots where at least three laser lines fall on the laser receiving target surface are not on the same straight line, and the laser lines are parallel to the moving direction of the measuring vehicle; The ring laser is arranged on the measuring trolley and is used to emit the ring laser to the inner wall of the pipeline; The camera is fixed on the measuring trolley and is used to shoot the ring laser; The data processing terminal is communicatively connected with the laser receiving target surface, the laser transmitter and the camera, and is used to calculate the position and posture of the measuring vehicle and the local coordinates of the annular laser point, and is also used to reconstruct the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point.

2. The pipeline inner wall measurement system according to claim 1, characterized in that: It also includes a synchronous controller, which is connected to the laser transmitter, the laser receiving target surface, the camera, and the ring laser.

3. The pipeline inner wall measurement system according to claim 1, characterized in that: The laser receiving target surface is arranged at the rear of the measuring trolley, the laser transmitter is arranged at the rear of the measuring trolley, the laser receiving target surface comprises a relative receiving surface and an opposite surface, the receiving surface receives the laser line, and the opposite surface is fixedly connected to the camera.

4. The pipeline inner wall measurement system according to claim 1, characterized in that: The camera shoots in front of the measuring trolley.

5. A method for measuring the inner wall of a pipeline, using the pipeline inner wall measuring system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Before the measurement begins, calibrate the relative position relationship between the camera and the ring laser; S2: At the beginning of measurement, push the measuring trolley into the initial position of the pipeline inlet; S3: During measurement, the measuring trolley moves forward to obtain the coordinates of the spot on the laser receiving target surface and the flight time of the laser, while the camera shoots the ring laser; S4: The position and posture of the measuring vehicle are obtained according to the coordinates of the spot in the laser receiving target surface and the flight time of the laser, and the local coordinates of the annular laser point are obtained according to the annular laser captured by the camera; S5: Reconstruct the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point.

6. The pipeline inner wall measurement method according to claim 5, characterized in that: Also includes: S6: Calculate pipeline straightness.

7. The pipeline inner wall measurement method according to claim 5, characterized in that: Step S2 also includes: turning on the laser transmitter, and recording the spot position received by the laser receiving target surface and the flight time of the laser.

8. The pipeline inner wall measurement method according to claim 7, characterized in that: In step S4, obtaining the position and posture of the measuring vehicle according to the coordinates of the spot on the laser receiving target surface and the flight time of the laser includes: S411: establishing a target plane coordinate system and a laser coordinate system, wherein the target plane coordinate system includes an initial state target plane coordinate system and a moving state target plane coordinate system; S412: Calculating the transformation relationship between the laser coordinate system and the initial state target plane coordinate system according to the flight time of the initial state laser and the coordinates of the initial state spot on the laser receiving target surface; S413: Calculating the transformation relationship between the laser coordinate system and the moving state target plane coordinate system according to the flight time of the moving state laser and the coordinates of the moving state spot on the laser receiving target surface; S414: Calculate the transformation relationship between the initial state target plane coordinate system and the moving state target plane coordinate system according to the above two transformation relationships to obtain the position and posture of the measuring vehicle.

9. The pipeline inner wall measurement method according to claim 7, characterized in that: In step S4, obtaining the local coordinates of the annular laser point according to the annular laser captured by the camera includes: S421: performing sub-pixel extraction on the ring laser in the image to obtain the center position of the laser point; S422: According to the relative position relationship between the camera and the ring laser, the local coordinates of the ring laser point on the pipeline are calculated using triangulation.

10. The pipeline inner wall measurement method according to claim 5, characterized in that: In step S5, reconstructing the three-dimensional shape of the inner wall of the pipeline according to the position and posture of the measuring vehicle and the local coordinates of the annular laser point includes: According to the position and posture of the measuring vehicle, the local coordinates of the annular laser point are converted into global coordinates to obtain the inner wall shape of the pipeline after three-dimensional reconstruction.

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