A control method for a robot for grinding weld seams in pipelines

Abstract

The present invention discloses a control method for a weld grinding robot in a pipeline, the method comprising: constructing a three-dimensional model of a target weld according to first coordinate data obtained by a three-dimensional laser scanner and second coordinate data obtained by a binocular camera; determining a tool setting point according to the three-dimensional model of the target weld, and controlling the grinding assembly to move to the tool setting point, grinding the target weld according to a first grinding scheme. After the grinding process is completed, the binocular camera collects a 360° image of the target weld for detection. If the detection result meets the preset grinding standard, the grinding is qualified; if the detection result does not meet the preset grinding standard, a second grinding scheme is generated according to the detection result, and the target weld is ground again according to the second grinding scheme until the grinding is qualified. Among them, the first coordinate data is the position data of the target weld obtained by scanning 360° with a three-dimensional laser scanner; the second coordinate data is the position data of the target weld obtained by collecting the target weld image with a binocular camera.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline robots, and in particular to a control method of a pipeline weld grinding robot. Background Art

[0002] In large-scale engineering fields such as oil pipeline laying and seawater desalination, pipelines are welded from sections of steel pipes. Liquids such as oil or seawater are highly corrosive. In order to increase the service life of the pipeline, the inside and outside of the pipeline must be treated with anti-corrosion. Before welding, each steel pipe is coated with an anti-corrosion coating on the inner wall of the pipeline for internal coating anti-corrosion treatment, and only a section without coating is reserved at both ends of the steel pipe. After the two steel pipes are welded together, the weld is coated with an internal coating patching technology at the construction site to coat the entire inside of the pipeline with anti-corrosion coating. Welding must be performed on the outside of the steel pipe, either manually or mechanically. The welds in the pipeline must be neat and symmetrical, and the weld height is very strict and cannot exceed the standard. Based on the above situation, patent CN202011333733.9 proposes a robot suitable for grinding welds in pipelines.

[0003] However, in actual operation, since the robot for grinding welds in pipelines in patent CN202011333733.9 needs to work deep inside the pipeline, manual control is often slow and the operation efficiency is low, while the accuracy of automatic control methods is often insufficient to meet the high-precision operation requirements. Summary of the invention

[0004] The embodiment of the present invention provides a control method for a pipeline weld grinding robot to solve the problem of insufficient grinding control accuracy of the pipeline weld grinding robot.

[0005] In order to solve the above technical problems, the embodiment of the present invention is implemented as follows:

[0006] The embodiment of the present invention provides a control method for a pipeline weld grinding robot, which is applied to a four-axis self-propelled pipeline weld grinding robot. The pipeline weld grinding robot includes: a mobile platform 1, a rotating component 2, a telescopic component 3, a grinding component 4, a three-dimensional laser scanner 5, a binocular camera 6, a distance sensor 7, a pressure sensor 8, a power supply 9 and a microprocessor 10; the grinding component 4, the three-dimensional laser scanner 5, the pressure sensor 8 and the binocular camera 6 are arranged on the telescopic component 3, the grinding component 4 is arranged at the outermost edge of the telescopic component 3, the measuring end of the three-dimensional laser scanner 5 faces the inner wall of the pipeline, the binocular camera 6 is arranged adjacent to the three-dimensional laser scanner 5, and the binocular cameras face the inner wall of the pipeline at an angle; the telescopic component 3 is arranged on the rotating component 2, and the rotating component 2 is fixed on the mobile platform 1; the grinding component 4 is provided with a grinding blade for grinding the weld. The method includes: constructing a three-dimensional model of the target weld according to the first coordinate data obtained by the three-dimensional laser scanner and the second coordinate data obtained by the binocular camera. The tool setting point is determined according to the three-dimensional model of the target weld, and when the microprocessor controls the grinding assembly to move to the tool setting point, the target weld is ground according to the first grinding scheme. After the grinding process is completed, the binocular camera collects the target weld image at 360° for detection. If the detection result meets the preset grinding standard, the grinding is qualified; if the detection result does not meet the preset grinding standard, a second grinding scheme is generated according to the detection result, and the target weld is ground again according to the second grinding scheme until the grinding is qualified. Among them, the first coordinate data is the position data of the target weld obtained by the 360° scanning of the three-dimensional laser scanner; the second coordinate data is the position data of the target weld obtained by spatial positioning after the microprocessor collects the target weld image through the binocular camera; the first grinding scheme includes: feed amount 0.1mm to 0.5mm, the maximum stroke is equal to the maximum width value of the target weld, and the stroke trajectory is in the shape of a "bow"; the second grinding scheme is a grinding scheme determined according to the detection results for specific items and specific weld areas that do not meet the preset grinding standards.

[0007] Optionally, a three-dimensional laser scanner scans the target weld 360° to obtain first coordinate data, and constructs an initial three-dimensional model of the target weld based on the first coordinate data; a binocular camera captures the target weld image 360°, and obtains second coordinate data through processing by a microprocessor; the microprocessor uses the second coordinate data to correct the initial three-dimensional model of the target weld to obtain a three-dimensional model of the target weld.

[0008] Optionally, before determining the tool setting point according to the target weld three-dimensional model, the method also includes: determining the highest point of the target weld three-dimensional model as the tool setting point according to the target weld three-dimensional model, and obtaining coordinate information of the tool setting point; calculating the relative position of the weld grinding robot in the pipeline and the tool setting point according to the coordinate information of the tool setting point; according to the relative position, the microprocessor controls the grinding assembly to move to the tool setting point, and when the pressure sensor detection result is greater than or equal to the first pressure threshold and less than the second pressure threshold, the tool setting is completed; wherein the first pressure threshold and the second pressure threshold are both preset values, and the first pressure threshold is greater than zero and not less than 2 times the measurement accuracy of the pressure sensor.

[0009] Optionally, before grinding the target weld according to the first grinding scheme, the method further includes: determining grinding parameters of the first grinding scheme according to feedback data from the pressure sensor and an initial three-dimensional model of the target weld.

[0010] Optionally, the grinding parameters of the first grinding scheme are determined according to the feedback data of the pressure sensor and the initial three-dimensional model of the target weld, specifically including: calculating the maximum width value of the target weld according to the initial three-dimensional model of the target weld, and determining the maximum width value of the target weld as the maximum stroke of the first grinding scheme; according to the feedback data of the pressure sensor, determining the feed amount corresponding to the interval where the feedback data of the pressure sensor is located as the feed amount of the first grinding scheme; the stroke trajectory of the first grinding scheme is in the shape of a "bow"; wherein, there are five intervals where the feedback data of the pressure sensor is located, corresponding to feed amounts of 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm, respectively.

[0011] Optionally, a second grinding scheme is generated based on the detection results, specifically including: determining specific items whose detection results do not meet the preset grinding standards; after the binocular camera collects the target weld image at 360°, obtaining the position information of the specific weld area that does not meet the preset grinding standards; increasing the feed amount of the first grinding scheme by 0.15 mm as the feed amount of the second grinding scheme; using the maximum width value of the specific weld area that does not meet the preset grinding standard as the axial stroke of the second grinding scheme, and using the maximum arc length of the specific weld area that does not meet the preset grinding standard as the circumferential stroke of the second grinding scheme; the stroke trajectory of the second grinding scheme is in the shape of an inverted "bow".

[0012] Optionally, the preset grinding standards include: weld excess height not exceeding 1.5 mm, weld acute angle not less than 45°, weld misalignment not exceeding 1.5 mm, weld width not exceeding 5 mm, and no cracks, pores, or slag inclusions on the weld surface.

[0013] Optionally, if the detection result meets the preset grinding standard, after the grinding is qualified, the method also includes: the microprocessor controls the weld grinding robot in the pipeline to move to the next weld or exit the pipeline.

[0014] Beneficial effects of the present invention:

[0015] 1. In terms of structure, compared with the prior art, the present invention innovatively uses a three-dimensional laser scanner, a binocular camera, and a pressure sensor to obtain more information to facilitate precise control by the microprocessor. The newly added pressure sensor is installed at the rear of the grinding assembly, which can accurately detect the pressure between the grinding assembly and the target weld, not only to achieve precise control of grinding, but also to prevent the pressure overload from causing motor failure. In addition, replacing the original STM32 microcontroller with a higher-performance microprocessor not only enables the three-dimensional laser scanner to quickly build a model, but also enables precise control of grinding based on the modeling.

[0016] 2. In terms of method, the present invention uses the first coordinate data of the three-dimensional laser scanner and the second coordinate data obtained by the binocular camera to jointly construct a three-dimensional model of the target weld, laying the foundation for the precise control of grinding. And through the first grinding scheme and the supplementary second grinding scheme, the parameters such as the stroke, feed amount, and stroke trajectory of the grinding component can be accurately controlled, thereby achieving precise control of the grinding of the target weld.

[0017] In summary, the present invention adjusts the robot structure for welding seam grinding in pipelines so as to obtain more information to lay a data foundation for precise control, and further improves the grinding control accuracy of the robot for welding seam grinding in pipelines by constructing a three-dimensional model of the target weld and refining the specific control method, so as to better meet the high-precision operation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a pipeline weld grinding robot;

[0019] Figure 2 This is a schematic diagram of a control method for a robot for grinding weld seams in pipelines;

[0020] Figure 3 This is the second schematic diagram of a control method for a robot for grinding welds in pipelines.

[0021] In the figure, 1-mobile platform, 2-rotation component, 3-telescopic component, 4-grinding component, 5-3D laser scanner, 6-binocular camera, 7-distance sensor, 8-pressure sensor, 9-power supply, 10-microprocessor. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0024] The terms "first" and "second" in the specification and claims of the present invention are used to distinguish different objects rather than to describe a specific order of the objects. For example, a first pressure threshold and a second pressure threshold are used to distinguish different thresholds rather than to describe a specific order of the thresholds.

[0025] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0026] In the description of the embodiments of the present invention, unless otherwise specified, “plurality” means two or more than two. For example, “plurality” means two or more than two elements.

[0027] The embodiment of the present invention provides a control method for a pipeline weld grinding robot, which is applied to Figure 1The four-axis self-propelled pipeline weld grinding robot shown is fully described in patent CN202011333733.9, but the robot used in the control method of this application is partially improved on the basis of the robot disclosed in patent CN202011333733.9, and the improvements include but are not limited to: three-dimensional laser scanner 5, binocular camera 6, pressure sensor 8 and microprocessor 10. Among them, the three-dimensional laser scanner 5 can more accurately collect the coordinate information of the target weld. The binocular camera 6 can more accurately detect the grinding of the target weld in real time and correct the weld modeling of the three-dimensional laser scanner. The newly added pressure sensor 8 is installed at the rear of the grinding assembly, which can accurately detect the pressure between the grinding assembly and the target weld, not only to achieve precise control of the grinding, but also to prevent the pressure from overloading and causing motor failure. In addition, replacing the original STM32 microcontroller with a higher-performance microprocessor can not only enable the three-dimensional laser scanner to quickly build a model, but also accurately control the grinding according to the modeling.

[0028] It should be noted that the following embodiments are Figure 1 The structure and principle of the four-axis self-propelled pipeline weld grinding robot shown are briefly described. For details, please refer to patent CN202011333733.9, which will not be repeated in this application.

[0029] Description of the structure and working principle: The mobile platform 1 is a four-wheeled power trolley, and the microprocessor can control its movement along the pipeline; the rotating component 2 and the telescopic component 3 respectively control the axial and circumferential movement of the grinding component 4 along the pipeline; the three-dimensional laser scanner 5 and the binocular camera 6 are used to collect weld coordinate data as a reference for controlling grinding; the distance sensor 7 is used to detect the displacement of the trolley; the pressure sensor 8 is used to detect the pressure between the grinding component and the target weld; the power supply 9 is connected to all power modules (including: various power modules such as control rotation, telescopic, grinding, platform movement, etc.) to provide power for them; the microprocessor 10 is used to collect data from the three-dimensional laser scanner 5 and the binocular camera to generate a weld model, and on the other hand, it is used to control the weld grinding robot in the entire pipeline to perform grinding operations on the weld.

[0030] like Figure 2 As shown, an embodiment of the present invention provides a control method for a pipeline weld grinding robot, which is applied to a four-axis self-propelled pipeline weld grinding robot ( Figure 1As shown in FIG. 1 , the pipeline weld grinding robot comprises: a mobile platform 1, a rotating component 2, a telescopic component 3, a grinding component 4, a three-dimensional laser scanner 5, a binocular camera 6, a distance sensor 7, a pressure sensor 8, a power supply 9 and a microprocessor 10; the grinding component 4, the three-dimensional laser scanner 5, the pressure sensor 8 and the binocular camera 6 are arranged on the telescopic component 3, the grinding component 4 is arranged at the outermost edge of the telescopic component 3, the measuring end of the three-dimensional laser scanner 5 faces the inner wall of the pipeline, the binocular camera 6 is arranged adjacent to the three-dimensional laser scanner 5, and the binocular cameras face the inner wall of the pipeline at an angle to each other; the telescopic component 3 is arranged on the rotating component 2, and the rotating component 2 is fixed on the mobile platform 1; the grinding component 4 is provided with a grinding blade for grinding the weld. The control method of the pipeline weld grinding robot can be implemented by the following steps 101 to 105, wherein step 104 and step 105 are selectively executed.

[0031] Step 101: The microprocessor constructs a three-dimensional model of a target weld according to first coordinate data acquired by a three-dimensional laser scanner and second coordinate data acquired by a binocular camera.

[0032] Among them, the above-mentioned first coordinate data is the position data of the target weld obtained by 360° scanning by a three-dimensional laser scanner; the second coordinate data is the position data of the target weld obtained by spatial positioning after the microprocessor collects the target weld image through a binocular camera.

[0033] Combination Figure 2 ,like Figure 3 As shown, the above step 101 can be specifically implemented through the following steps 101a to 101c.

[0034] Step 101a: The three-dimensional laser scanner scans the target weld 360° to obtain first coordinate data, and transmits the first coordinate data to the microprocessor. The microprocessor constructs an initial three-dimensional model of the target weld according to the first coordinate data.

[0035] Optionally, since the preset grinding standard is 0.1mm, it is recommended to use an accuracy of 0.1mm when selecting a 3D laser scanner. There is no need for too high accuracy to increase equipment investment costs.

[0036] It should be noted that the 3D laser scanner can scan the entire target weld in a 360° circular manner to obtain the coordinate information of each point of the target weld (the coordinate information is relative to the 3D scanner's own coordinate system). After being transmitted to the microprocessor, the microprocessor combines the distance sensor and the position of the mobile platform to convert the position coordinates of each point of the target weld from the 3D scanner's own coordinate system to the mobile platform coordinate system, so that the grinding of the rotating component and the movement of the mobile platform can be better controlled based on the mobile platform coordinate system. Subsequently, the entire target weld is reconstructed in three dimensions based on the optical triangulation method, and the initial three-dimensional model of the target weld is established.

[0037] Step 101b: The binocular camera collects the target weld image at 360° and processes it through the microprocessor to obtain the second coordinate data.

[0038] It should be noted that the microprocessor processes the second coordinate data mainly using spatial positioning technology, and the specific implementation process is as follows:

[0039] A. Obtain two images of the same time frame from the binocular camera and convert them into grayscale images; at the same time, obtain the intrinsic parameters of the two cameras.

[0040] B. Perform distortion correction and stereo correction on the above two grayscale images.

[0041] C. Use the two corrected grayscale images to construct the SGBM object using the SGBM algorithm and calculate the disparity map.

[0042] D. The second coordinate data of the target weld is obtained through the disparity map coordinate calculation, and the same processing is performed on other time frame images in turn to achieve the tracking of the target weld.

[0043] Step 101c: The microprocessor uses the second coordinate data to correct the initial three-dimensional model of the target weld to obtain the three-dimensional model of the target weld.

[0044] It should be noted that since the angle and direction of the three-dimensional scanner to obtain the first coordinate data are relatively single, the data of the initial three-dimensional model of the target weld obtained based on the first coordinate data at the inflection point and the low point of the model are basically obtained based on the data interpolation fitting of several points. Therefore, these points of the initial three-dimensional model of the target weld need to be filled with data. The second coordinate data obtained by the binocular camera in the present invention can obtain more data around the inflection point and the low point because the two cameras are shooting at different angles. Therefore, it can better make up for the shortcomings of the above-mentioned three-dimensional scanner, so that the corrected three-dimensional model of the target weld is closer to the actual weld, laying a foundation for improving the grinding control accuracy.

[0045] Optionally, the microprocessor uses a machine learning method to correct the initial three-dimensional model, and specifically uses a neural network algorithm and data fusion technology as the correction method. The implementation method is: first, the first coordinate data and the second coordinate data are simultaneously used as input to embed the neural network model of the data fusion algorithm; then, the parameters are adjusted to minimize the loss function and the fused data has a good degree of conformity with the first coordinate data and the second coordinate data; then, the fused coordinate data is output, and the three-dimensional model is constructed using the fused coordinate data to obtain the target weld three-dimensional model.

[0046] Step 102: The microprocessor determines a tool setting point according to the three-dimensional model of the target weld, and when the microprocessor controls the grinding assembly to move to the tool setting point, the target weld is ground according to a first grinding scheme.

[0047] Among them, the above-mentioned first grinding scheme includes: a feed amount of 0.1mm to 0.5mm, a maximum stroke equal to the maximum width value of the target weld, and a stroke trajectory in the shape of a "bow".

[0048] It should be noted that the specific steps of determining the first grinding scheme in the above step 102 are referred to in the following steps 107 to 110, which will not be described in detail here.

[0049] Step 103: After the grinding process is completed, the binocular camera collects 360° images of the target weld for detection.

[0050] It should be noted that the specific method of detecting the target weld image by the binocular camera or real-time detection is referred to the specific method of tracking the target weld in step 101b, which will not be repeated here.

[0051] Step 104: If the detection result meets the preset grinding standard, the grinding is qualified.

[0052] Optionally, the preset grinding standards include: weld excess height not exceeding 1.5 mm, weld acute angle not less than 45°, weld misalignment not exceeding 1.5 mm, weld width not exceeding 5 mm, and no cracks, pores, or slag inclusions on the weld surface.

[0053] It should be noted that the above-mentioned preset grinding standards have been programmed and used as the judgment standard of the microprocessor. Specifically, during the inspection, the microprocessor obtains the coordinate data collected by the binocular camera in real-time detection (obtained in the same way as the second coordinate data, but at this time these coordinate data are used to characterize the actual situation of the target weld after grinding), and successively obtains the weld excess height, weld sharp angle, weld misalignment, weld width and other data through coordinate calculation and compares and judges with the above-mentioned preset grinding standards. In addition, the absence of cracks, pores, and slag inclusions on the weld surface is mainly judged by the continuity and integrity of the local data (especially the weld image data) in the image collected by the binocular camera. In other words, when the weld excess height, weld sharp angle, weld misalignment, and weld width all meet the above-mentioned preset grinding standards, and the continuity and integrity of the data in the image collected by the binocular camera are within a certain range, it is judged that the inspection result meets the preset grinding standard and the grinding is qualified.

[0054] Step 105: If the detection result does not meet the preset grinding standard, a second grinding scheme is generated according to the detection result, and the target weld is ground again according to the second grinding scheme until the grinding is qualified.

[0055] The second grinding scheme is a grinding scheme determined according to the test results for specific items and specific weld areas that do not meet the preset grinding standards.

[0056] Optionally, the “generating a second grinding plan according to the detection result” in the above step 5 can be specifically implemented through the following steps 105a to 105e.

[0057] Step 105a: Determine the specific items whose test results do not meet the preset grinding standards.

[0058] It should be noted that the above-mentioned specific items that do not meet the preset grinding standards include at least one of the following: weld excess height, weld sharp angle, weld misalignment, and weld width.

[0059] Step 105b: After the binocular camera captures the target weld image at 360°, the position information of the specific weld area that does not meet the preset grinding standard is obtained.

[0060] It should be noted that the position information of the specific weld area that does not meet the preset grinding standard is obtained through real-time detection of the binocular camera and the coordinate data is collected (the acquisition method refers to the second coordinate data), and the position coordinates of the specific weld area that does not meet the preset grinding standard are determined based on the coordinate data.

[0061] Step 105c: increase the feed rate of the first grinding solution by 0.15 mm as the feed rate of the second grinding solution.

[0062] Specifically, the determination of the first grinding scheme refers to the following steps 110a to 110c. Since the second grinding scheme is a regrinding of the defects of the first grinding scheme, the target weld has been ground once and there is no excessive welding slag. Therefore, the feed amount of the second grinding scheme can be appropriately selected to increase the feed amount of the first grinding scheme by 0.15mm.

[0063] Step 105d: taking the maximum width value of the specific weld area that does not meet the preset grinding standard as the axial stroke of the second grinding solution, and taking the maximum arc length of the specific weld area that does not meet the preset grinding standard as the circumferential stroke of the second grinding solution.

[0064] Optionally, according to the position coordinates of the specific weld area that does not meet the preset grinding standard obtained in the above step 105b, the maximum width of the specific weld area that does not meet the preset grinding standard can be directly calculated.

[0065] In addition, according to the position coordinates of the specific weld area that does not meet the preset grinding standard obtained in the above step 105b, and the movement radius of the grinding assembly is calculated through the coordinates, multiple arc lengths are calculated according to the movement radius and the coordinates of the points in the specific weld area along the arc length direction, and the sizes are compared to obtain the maximum arc length of the specific weld area that does not meet the preset grinding standard.

[0066] Step 105e, the travel trajectory of the second grinding solution is in the shape of an inverted "bow".

[0067] It should be noted that the reverse "bow"-shaped stroke means that the grinding component (or grinding tool) first moves a maximum stroke from right to left (usually equal to the weld width); then, it moves a feed amount radially (for example, 0.1 mm in the radial direction away from the axis); then, it moves a maximum stroke from left to right again, and so on, repeating the above actions back and forth.

[0068] Optionally, after “if the detection result meets the preset grinding standard, the grinding is qualified” in the above step 104 or step 105, the control method of the pipeline weld grinding robot may further include the following step 106.

[0069] Step 106: The microprocessor controls the pipeline weld grinding robot to move to the next weld or exit the pipeline.

[0070] Optionally, before “determining the tool setting point according to the target weld three-dimensional model” in step 102 , the control method of the in-pipe weld grinding robot further includes the following steps 107 to 109 .

[0071] Step 107: Based on the target weld three-dimensional model, the microprocessor determines the highest point of the target weld three-dimensional model as the tool setting point, and obtains the coordinate information of the tool setting point.

[0072] It should be noted that the highest point of the target weld three-dimensional model refers to the highest point of the entire annular weld, that is, the point closest to the central axis of the pipeline.

[0073] Step 108: Calculate the relative position of the pipeline weld grinding robot and the tool setting point according to the coordinate information of the tool setting point.

[0074] It should be noted that the above calculation of the relative position between the in-pipe weld grinding robot and the tool setting point is completed through the points in the initial three-dimensional model of the target weld, wherein the reference point of the in-pipe weld grinding robot is calculated with reference to the coordinates of the mobile platform in the above step 101a.

[0075] Step 109: According to the relative position, the microprocessor controls the grinding assembly to move to the tool setting point, and when the detection result of the pressure sensor is greater than or equal to the first pressure threshold and less than the second pressure threshold, the tool setting is completed.

[0076] The first pressure threshold and the second pressure threshold are both preset values, and the first pressure threshold is greater than zero and not less than twice the measurement accuracy of the pressure sensor.

[0077] It should be noted that the pressure sensor is installed at the rear of the grinding assembly, which can accurately detect the pressure between the grinding assembly and the target weld, not only to achieve precise control of grinding, but also to prevent the pressure overload from causing motor failure. Among them, the first pressure threshold is greater than zero, and is not less than 2 times the measurement accuracy of the pressure sensor, and not more than 5 times the measurement accuracy of the pressure sensor. The second pressure threshold is set according to the pressure conditions during historical motor failures.

[0078] Optionally, before “grinding the target weld according to the first grinding scheme” in step 102 , the in-pipe weld grinding robot control method may further include the following step 110 .

[0079] Step 110: Determine grinding parameters of a first grinding solution according to feedback data from the pressure sensor and an initial three-dimensional model of the target weld.

[0080] Optionally, the above step 110 can be specifically implemented through the following steps 110a to 110c.

[0081] Step 110a, calculating the maximum width value of the target weld according to the initial three-dimensional model of the target weld, and determining the maximum width value of the target weld as the maximum stroke of the first grinding scheme.

[0082] Step 110b: According to the feedback data of the pressure sensor, the feed rate corresponding to the interval where the feedback data of the pressure sensor is located is determined as the feed rate of the first grinding solution.

[0083] Among them, there are five intervals in which the feedback data of the pressure sensor is located, corresponding to feed amounts of 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm respectively.

[0084] It should be noted that the feedback data of the pressure sensor is related to the material hardness of the weld and the pressure between the grinding assembly and the target weld.

[0085] Specifically, the data between the first pressure threshold and the second pressure threshold are divided into five intervals (e.g., the first interval to the fifth interval), and correspond to the feed amounts 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm in order from small to large. When the feedback data of the pressure sensor falls into the second interval, the corresponding feed amount is 0.2mm.

[0086] Step 110c: The travel trajectory of the first grinding solution is in the shape of a "bow".

[0087] It should be noted that the "bow"-shaped stroke means that the grinding component (or grinding tool) first moves a maximum stroke (usually equal to the weld width) from left to right; then, it moves a feed amount in the radial direction (for example, 0.1 mm in the radial direction away from the axis); then, it moves a maximum stroke from right to left, and the above actions are repeated reciprocally.

[0088] The embodiment of the present invention provides a control method for a weld grinding robot in a pipeline. In terms of structure, compared with the prior art, the present invention innovatively uses a three-dimensional laser scanner, a binocular camera, and a pressure sensor to obtain more information to facilitate the microprocessor to perform precise control, wherein the newly added pressure sensor is installed at the rear of the grinding assembly, and can accurately detect the pressure between the grinding assembly and the target weld, which can not only achieve precise control of grinding, but also prevent the pressure from overloading and causing motor failure. In addition, the original STM32 single-chip microcomputer is replaced with a microprocessor with higher performance, which can not only enable the three-dimensional laser scanner to quickly build a model, but also can accurately control the grinding according to the modeling. In terms of method, the present invention uses the first coordinate data of the three-dimensional laser scanner and the second coordinate data obtained by the binocular camera to jointly construct a three-dimensional model of the target weld, laying the foundation for the precise control of grinding. And through the first grinding scheme and the supplementary second grinding scheme, the parameters such as the stroke, feed amount, and stroke trajectory of the grinding assembly can be accurately controlled, thereby achieving precise control of the grinding of the target weld. In summary, the present invention adjusts the robot structure for welding seam grinding in pipelines so as to obtain more information to lay a data foundation for precise control, and further improves the grinding control accuracy of the robot for welding seam grinding in pipelines by constructing a three-dimensional model of the target weld and refining the specific control method, so as to better meet the high-precision operation requirements.

[0089] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions and substitutions made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A control method for a pipeline weld grinding robot, characterized in that: The invention is applied to a four-axis self-propelled pipeline weld grinding robot, the pipeline weld grinding robot comprising: a mobile platform (1), a rotating component (2), a telescopic component (3), a grinding component (4), a three-dimensional laser scanner (5), a binocular camera (6), a distance sensor (7), a pressure sensor (8), a power supply (9) and a microprocessor (10); the grinding component (4), the three-dimensional laser scanner (5), the pressure sensor (8) and the binocular camera (6) are arranged on the telescopic component (3), the grinding component (4) is arranged at the outermost edge of the telescopic component (3), the measuring end of the three-dimensional laser scanner (5) faces the inner wall of the pipeline, the binocular camera (6) is arranged adjacent to the three-dimensional laser scanner (5), and the binocular cameras face the inner wall of the pipeline at an angle to each other; the telescopic component (3) is arranged on the rotating component (2), and the rotating component (2) is fixed on the mobile platform (1); the grinding component (4) is provided with a grinding blade for grinding the weld; the method comprises: Constructing a target weld three-dimensional model according to the first coordinate data acquired by the three-dimensional laser scanner and the second coordinate data acquired by the binocular camera; Determine a tool setting point according to the target weld three-dimensional model, and when the microprocessor controls the grinding assembly to move to the tool setting point, grind the target weld according to a first grinding scheme; After the grinding process is completed, the binocular camera collects the target weld image at 360° for detection; If the test results meet the preset grinding standards, the grinding is qualified; If the detection result does not meet the preset grinding standard, a second grinding scheme is generated according to the detection result, and the target weld is ground again according to the second grinding scheme until the grinding is qualified; Among them, the first coordinate data is the position data of the target weld obtained by 360° scanning by the three-dimensional laser scanner; the second coordinate data is the position data of the target weld obtained by spatial positioning after the microprocessor collects the target weld image through the binocular camera; the first grinding scheme includes: a feed amount of 0.1mm to 0.5mm, a maximum stroke equal to the maximum width value of the target weld, and a stroke trajectory in the shape of a "bow"; the second grinding scheme is a grinding scheme determined according to the detection results for specific items and specific weld areas that do not meet the preset grinding standards.

2. The control method of the pipeline weld grinding robot according to claim 1, characterized in that: The method of constructing a target weld three-dimensional model according to the first coordinate data acquired by the three-dimensional laser scanner and the second coordinate data acquired by the binocular camera comprises: The three-dimensional laser scanner scans the target weld at 360° to obtain the first coordinate data, and constructs an initial three-dimensional model of the target weld according to the first coordinate data; The binocular camera collects the target weld image at 360°, and obtains the second coordinate data through processing by the microprocessor; The microprocessor uses the second coordinate data to correct the initial three-dimensional model of the target weld to obtain the three-dimensional model of the target weld.

3. The control method of the pipeline weld grinding robot according to claim 2, characterized in that: Before determining the tool setting point according to the target weld three-dimensional model, the method further includes: According to the target weld three-dimensional model, determining the highest point of the target weld three-dimensional model as the tool setting point, and acquiring coordinate information of the tool setting point; Calculating the relative position between the in-pipe weld grinding robot and the tool setting point according to the coordinate information of the tool setting point; According to the relative position, the microprocessor controls the grinding assembly to move to the tool setting point, and when the detection result of the pressure sensor is greater than or equal to the first pressure threshold and less than the second pressure threshold, the tool setting is completed; The first pressure threshold and the second pressure threshold are both preset values, and the first pressure threshold is greater than zero and not less than twice the measurement accuracy of the pressure sensor.

4. The control method of a pipeline weld grinding robot according to claim 1, characterized in that: Before grinding the target weld according to the first grinding scheme, the method further includes: The grinding parameters of the first grinding scheme are determined according to the feedback data of the pressure sensor and the initial three-dimensional model of the target weld.

5. The control method of a pipeline weld grinding robot according to claim 4, characterized in that: Determining the grinding parameters of the first grinding scheme according to the feedback data of the pressure sensor and the initial three-dimensional model of the target weld includes: Calculating the maximum width value of the target weld according to the initial three-dimensional model of the target weld, and determining the maximum width value of the target weld as the maximum stroke of the first grinding scheme; According to the feedback data of the pressure sensor, determining the feed amount corresponding to the interval where the feedback data of the pressure sensor is located as the feed amount of the first grinding scheme; The travel trajectory of the first grinding scheme is in the shape of a "bow"; Among them, there are five intervals in which the feedback data of the pressure sensor is located, corresponding to feed amounts of 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm respectively.

6. The control method of a pipeline weld grinding robot according to claim 1, characterized in that: Generating a second grinding scheme according to the detection result comprises: Determine the specific items in which the test results do not meet the preset grinding standards; After the binocular camera acquires the target weld image at 360°, the position information of the specific weld area that does not meet the preset grinding standard is obtained; The feed amount of the first grinding scheme is increased by 0.15 mm as the feed amount of the second grinding scheme; Using the maximum width value of the specific weld area that does not meet the preset grinding standard as the axial stroke of the second grinding scheme, and using the maximum arc length of the specific weld area that does not meet the preset grinding standard as the circumferential stroke of the second grinding scheme; The travel trajectory of the second grinding scheme is in the shape of an inverted "bow".

7. The control method of a pipeline weld grinding robot according to any one of claims 1 to 6, characterized in that: The preset grinding standards include: weld excess height is not greater than 1.5mm, weld acute angle is not less than 45°, weld misalignment is not greater than 1.5mm, weld width is not greater than 5mm, and there are no cracks, pores, or slag inclusions on the weld surface.

8. The control method of a pipeline weld grinding robot according to any one of claims 1 to 6, characterized in that: If the detection result meets the preset grinding standard, after the grinding is qualified, the method further includes: The microprocessor controls the in-pipe weld grinding robot to move to the next weld or exit the pipeline.

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