A method for secondary positioning of a workpiece

Abstract

The application discloses a workpiece secondary positioning method. The application comprises the following steps: acquiring ideal position coordinates of the target workpiece, wherein the ideal position coordinates comprise position coordinates of any point on the target workpiece; scanning the target workpiece after the target workpiece is positioned, processing point cloud information of the target workpiece, extracting process hole center point coordinates on the outer surface of the target workpiece, and preliminarily adjusting the position of a hole exploration mechanism; and performing secondary positioning on the process hole to acquire actual position coordinates of the target workpiece. Through the application, the problem of large positioning error of a large workpiece in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of workpiece coating technology, and more particularly to a method for secondary positioning of workpieces. Background Technology

[0002] In related technologies, the placement of large workpieces often relies on manual placement, which is prone to significant errors. Automated workpiece processing (spraying, sandblasting, welding, etc.) demands high precision in workpiece positioning. Therefore, data support is crucial for subsequent automated processing. For example, for cavity-type workpieces, automated equipment needs to drill into process holes for spraying, welding, and other operations. Existing technologies only position the workpiece itself but cannot perform secondary positioning of the process holes, resulting in positioning accuracy insufficient to support automated equipment drilling into these holes.

[0003] There is currently no effective solution to the aforementioned problems in the relevant technologies. Summary of the Invention

[0004] The main objective of this application is to provide a method for secondary positioning of workpieces, so as to at least solve the problem of large positioning errors of large workpieces in related technologies.

[0005] To achieve the above objectives, according to one aspect of this application, a method for secondary positioning of a workpiece is provided. The method includes: obtaining the ideal position coordinates of a target workpiece, the ideal position coordinates including the position coordinates of any point on the target workpiece; scanning the target workpiece after it is positioned, processing the point cloud information of the target workpiece, extracting the coordinates of the center point of the process hole on the outer surface of the target workpiece, and initially adjusting the position of the probing mechanism; and performing secondary positioning of the process hole to obtain the actual position coordinates of the target workpiece.

[0006] Optionally, the point cloud information is sampled and denoised; the processed point cloud is projected onto a planar coordinate system and converted into a two-dimensional image; the region of the process hole is identified in the two-dimensional image; the process hole region is fitted with a circle to extract the center point of the process hole; the center point of the process hole is back-projected into three-dimensional space to obtain the coordinates of the center point of the process hole.

[0007] Optionally, the positional deviation between the actual and ideal coordinates of the center point of the process hole on the outer surface is calculated; the cave exploration mechanism is then preliminarily adjusted based on the positional deviation.

[0008] Optionally, when the following conditions are met When the transformation error is minimized, the rotation and translation matrices are obtained, where... These are the actual location coordinates. For ideal position coordinates, It is a 3×3 rotation matrix. It is a 3×1 translation matrix.

[0009] Optionally, the camera at the end of the tunneling mechanism takes a picture of the process hole after reaching the stop point. The camera then extracts the three-dimensional position information of the process hole using the hand-eye calibration method. The camera calculates the quadratic rotation matrix and the quadratic translation matrix between the three-dimensional position information of the process hole and the ideal position coordinates. The camera then obtains the actual position coordinates of the target workpiece based on the quadratic rotation matrix and the quadratic translation matrix.

[0010] Optionally, starting from the actual position coordinates of the center point of the process hole on the outer surface, the plan is made by adjusting a preset distance along the axis of the process hole each time. When the planned position meets the visual positioning requirements, the preset distance with the least adjustment is obtained as the photo offset distance. Based on the photo offset distance, the coordinates of the photo stopping point are obtained.

[0011] This application employs the following steps: obtaining the ideal position coordinates of the target workpiece, which include the position coordinates of any point on the target workpiece; after the target workpiece is positioned, scanning the target workpiece, processing the point cloud information of the target workpiece, extracting the coordinates of the center point of the process hole on the outer surface of the target workpiece, and initially adjusting the position of the probing mechanism; and performing secondary positioning of the process hole to obtain the actual position coordinates of the target workpiece, thus solving the problem of large positioning errors of large workpieces in related technologies, thereby achieving the effect of positioning while operating, making the positioning results accurate. Attached Figure Description

[0012] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 This is a flowchart of a method for secondary positioning of a workpiece according to an embodiment of this application. Detailed Implementation

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0015] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0016] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0018] This embodiment provides a method for secondary positioning of a workpiece that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0019] Figure 1 This is a flowchart of a method for secondary positioning of a workpiece according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0020] Step S101: Obtain the ideal position coordinates of the target workpiece, which include the position coordinates of any point on the target workpiece;

[0021] Specifically, the preset ideal position coordinates of the workpiece include the position coordinates of every point on the workpiece, which can be obtained through simulation software. Since the workpiece may shift during actual operation, the overall spraying is first simulated under ideal conditions. This way, when obtaining the actual position later, the actual coordinates can be obtained simply by conversion.

[0022] Step S102: After the target workpiece is positioned, the target workpiece is scanned, the point cloud information of the target workpiece is processed, the coordinates of the center point of the process hole on the outer surface of the target workpiece are extracted, and the position of the tunneling mechanism is initially adjusted.

[0023] Specifically, the position of the cave exploration mechanism is first adjusted so that the processing equipment can reach the appropriate shooting point for taking pictures. Adjusting the position of the cave exploration mechanism is the basis for taking pictures. If the subsequent offset is too large, the moving mechanism can be adjusted again. The cave exploration mechanism is set on the moving mechanism.

[0024] Step S103: Perform secondary positioning of the process hole to obtain the actual position coordinates of the target workpiece.

[0025] Specifically, during the caving process, the process hole is repositioned. The telescopic arm is extended to the stopping point for taking pictures, and then the process hole is photographed to obtain the coordinates of its center point. Then, based on the ideal coordinates of the process hole's center point, a rotation matrix and a translation matrix are obtained, which allows for the accurate determination of the actual position coordinates of the target workpiece.

[0026] In one optional embodiment, the point cloud information is sampled and denoised; the processed point cloud is projected onto a planar coordinate system and converted into a two-dimensional image; the area of ​​the process hole is identified in the two-dimensional image; the process hole area is circle fitted to extract the center point of the process hole; the center point of the process hole is back-projected into three-dimensional space to obtain the coordinates of the center point of the process hole.

[0027] Specifically, the telescopic arm extends into the forging die through the process hole. Due to the large size of the forging die, the telescopic arm's extension length exceeds 10m. Because the process hole is relatively small, to prevent collisions between the telescopic arm and the process hole during insertion, the optimal insertion angle is to insert the arm perpendicularly into the process hole from its center. Considering the influence of manual positioning and processing errors, the actual forging posture will inevitably deviate from the model. If the insertion is performed according to the model's program, interference will occur. Therefore, it is necessary to position the forging die and feed back the posture deviation to the RGV and robot, or directly adjust the position of the telescopic arm mechanism to adjust its trajectory. LiDAR is used to identify the forging position deviation and locate the process hole, providing a positional basis for the robot to photograph the process hole with a camera. The process involves: LiDAR scanning the forging die to obtain point cloud information → sampling and denoising the point cloud → extracting the plane and projecting it into a planar coordinate system → converting it into a 2D image → locating the process hole region → performing circle fitting on the process hole → finding the center point of the process hole → back-projecting it into 3D.

[0028] In one alternative embodiment, the positional deviation between the actual position coordinates and the ideal position coordinates of the center point of the process hole on the outer surface is calculated; and the cave exploration mechanism is initially adjusted based on the positional deviation.

[0029] Specifically, after obtaining the deviation, the position of the moving mechanism can be initially adjusted to prepare for subsequent secondary positioning.

[0030] In an alternative embodiment, when the following conditions are met... When the transformation error is minimized, the rotation and translation matrices are obtained, where... These are the actual location coordinates. For ideal position coordinates, It is a 3×3 rotation matrix. It is a 3×1 translation matrix.

[0031] Specifically, for example, select three process holes on a workpiece, and in the simulation software, determine the ideal coordinates of the center points of the three process holes in the base coordinate system. ,in Indicates the ideal position of the center point of the hole. Represents the ideal direction vector of the hole. .

[0032] The workpiece placement may have deviations, so the actual position coordinates of the three process holes in the base coordinate system are as follows. .in Indicates the actual position of the center point of the hole. This represents the actual vector indicating the direction of the hole. .

[0033] The actual coordinates of the center of the process hole on the workpiece are obtained by scanning the outline of the process hole with a laser scanner and fitting the coordinates of the center of the process hole.

[0034] Known and Then we can find the optimal R and t such that and The transformation error between the two coordinates is minimized, i.e., it satisfies... Where R is a 3×3 rotation matrix and t is a 3×1 translation matrix.

[0035] In one alternative embodiment, a photographing stop point is obtained; after the camera at the end of the tunneling mechanism reaches the photographing stop point, it takes a picture of the process hole and extracts the three-dimensional position information of the process hole according to the hand-eye calibration method.

[0036] Specifically, since the centers of the process holes inside some workpieces are not on a straight line, when the processing equipment needs to enter the workpiece through the telescopic arm, it is necessary to perform secondary positioning on each process hole. This ensures the accuracy of the overall actual position coordinates of the workpiece, as well as the accuracy of the exploration hole and processing in the partition.

[0037] In one optional embodiment, the quadratic rotation matrix and quadratic translation matrix between the three-dimensional position information of the process hole and the ideal position coordinates are calculated; the actual position coordinates of the target workpiece are obtained based on the quadratic rotation matrix and the quadratic translation matrix.

[0038] Specifically, since an adjustment has already been made through the external process holes, the second positioning adjustment will be more accurate.

[0039] In one optional embodiment, the planning is carried out by adjusting a preset distance each time along the axis of the process hole, starting from the actual position coordinates of the center point of the process hole on the outer surface. When the planned position meets the visual positioning requirements, the preset distance with the least adjustment is obtained as the shooting offset distance. Based on the shooting offset distance, the coordinates of the shooting stop point are obtained.

[0040] Specifically, assuming there is One process hole, indexed as process holes The center coordinates are ,in, These are position coordinates. It is a rotation coordinate system, the stopping point of the photo. The coordinates are

[0041] in It is the stopping point With process holes Distance in the x-direction from the center point. Position coordinates. Rotation coordinates exist and The values ​​are the same.

[0042] Conditional function Indicates when the stopping point is At that time, is the robot's photo-taking trajectory planning successful (i.e., the robot deploys without interference and takes clear photos, meeting the visual positioning requirements)? Simulation software from Start, gradually increase (For example, with step size) (Incrementing), repeatedly planning the robot's photo-taking trajectory until the minimum value that satisfies the conditions is found. For each process hole Solve for, where, ,in This is the final determined distance to the telescopic arm's stopping point for taking photos. If such a distance does not exist... If not, the planning fails. For all process holes... The coordinates of the stopping point for taking the photo are: This process ensures that the robot can take pictures of each process hole under conditions that meet the requirements of no interference and clear imaging.

[0043] The technical effects of this invention are as follows: This invention solves industry pain points such as placement deviation of large forged workpieces, interference from long-stroke telescopic arms, and insufficient positioning accuracy of process holes, significantly improving the reliability and accuracy of workpiece alignment and hole probing. This invention relies on simulation software to pre-store the ideal coordinates of the entire workpiece, completing the ideal state operation simulation in advance. This provides a precise benchmark for the actual workpiece's pose conversion and deviation correction, avoiding the original error problems caused by manual positioning, equipment processing, and workpiece placement. Simultaneously, through systematic processing of lidar point cloud sampling, noise reduction, projection conversion, circle fitting, and 3D back projection, the 3D coordinates of the process hole center are accurately extracted, enabling rapid identification of the actual pose deviation of large forged workpieces and providing data support for initial mechanism adjustments. This invention solves for the optimal rotation and translation matrices, achieving accurate calculation of workpiece pose deviation. Combined with adaptive planning technology for the process hole photography stop point, the optimal photography position is determined with the minimum offset distance, completely solving problems such as easy collisions during long telescopic arm insertion, poor photography field of view, and trajectory interference, ensuring clear visual positioning and compliant operation trajectory. Through a dual-layer calibration mode of initial adjustment and secondary fine positioning, the errors of single positioning are corrected, accurately locking the actual position coordinates of the workpiece and effectively adapting to complex workpiece structures with multiple non-collinear process holes. The overall technical solution realizes automated detection, calculation, and adaptive adjustment of workpiece posture deviation and mechanism trajectory, significantly improving the stability, safety, and positioning accuracy of drilling operations on large die-forged workpieces, and providing core technical support for the high-quality implementation of subsequent processes such as spraying and partition processing.

[0044] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0045] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0046] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0047] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0048] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0049] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0050] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0051] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0052] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for secondary positioning of a workpiece, characterized in that, include: Obtain the ideal position coordinates of the target workpiece, wherein the ideal position coordinates include the position coordinates of any point on the target workpiece; After the target workpiece is placed, the target workpiece is scanned, the point cloud information of the target workpiece is processed, the coordinates of the center point of the process hole on the outer surface of the target workpiece are extracted, and the position of the tunneling mechanism is initially adjusted according to the ideal position coordinates. The actual position coordinates of the target workpiece are obtained by performing secondary positioning on the process hole; The secondary positioning of the process hole to obtain the actual position coordinates of the target workpiece includes: Obtain the stopping point for taking the photo; After the camera at the end of the cave exploration mechanism reaches the stopping point for taking pictures, it takes pictures of the process hole and extracts the three-dimensional position information of the process hole according to the hand-eye calibration method. Calculate the quadratic rotation matrix and quadratic translation matrix between the three-dimensional position information of the process hole and the ideal position coordinates; The actual position coordinates of the target workpiece are obtained based on the second rotation matrix and the second translation matrix.

2. The method according to claim 1, characterized in that, After the target workpiece is positioned, it is scanned, its point cloud information is processed, the coordinates of the center point of the process hole on the outer surface of the target workpiece are extracted, and the position of the moving mechanism is initially adjusted, including: The point cloud information is sampled and denoised. The processed point cloud is projected onto a planar coordinate system and converted into a two-dimensional image. Identify the region of the process hole in the two-dimensional image; Perform a circle fit on the process hole region and extract the center point of the process hole; The center point of the process hole is back-projected into three-dimensional space to obtain the coordinates of the center point of the process hole.

3. The method according to claim 1, characterized in that, Preliminary adjustments to the location of the cave exploration equipment include: Calculate the positional deviation between the actual position coordinates and the ideal position coordinates of the center point of the process hole on the outer surface; The cave exploration mechanism is initially adjusted based on the positional deviation.

4. The method according to claim 3, characterized in that, Calculating the positional deviation between the actual and ideal coordinates of the center point of the process hole on the outer surface includes: When satisfied When the transformation error is minimized, the rotation and translation matrices are obtained, where... These are the actual location coordinates. For ideal position coordinates, It is a 3×3 rotation matrix. It is a 3×1 translation matrix.

5. The method according to claim 1, characterized in that, Obtain the stop point for taking the photo, including: Starting from the actual position coordinates of the center point of the process hole on the outer surface, the plan is made by adjusting a preset distance along the axis of the process hole each time. When the planned position meets the visual positioning requirements, the preset distance with the least adjustment is obtained as the shooting offset distance. Based on the shooting offset distance, the coordinates of the shooting stop point are obtained.

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