A laser cleaning path automatic planning method and a laser cleaning device

Abstract

The present application relates to a kind of laser cleaning path automatic planning method and laser cleaning device, obtain the three-dimensional information of the workpiece to be cleaned, planning cleaning path and obtaining the partition cleaning strategy of the workpiece to be cleaned, the galvanometer adjustment information of laser cleaning equipment is configured, control laser cleaning equipment is cleaned according to the partition cleaning strategy planned to the workpiece to be cleaned, and based on galvanometer adjustment information, real-time adjustment galvanometer is adapted to the change of the surface shape of the workpiece to be cleaned;Device includes base, position transfer unit realizes the position movement of device except base, its output end is provided with three-dimensional scanning construction unit, for scanning the workpiece to be cleaned and constructing the three-dimensional information of workpiece, finally with laser cleaning unit to the workpiece to be cleaned laser cleaning.The present application improves cleaning efficiency, completes the intelligent selection of cleaning path and cleaning strategy, reduces the redundancy and repetition of cleaning path, reduces the loophole of cleaning work, ensures the integrity and comprehensiveness of cleaning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of calculation, estimation or counting, in particular to a laser cleaning path automatic planning method and a laser cleaning device. BACKGROUND

[0002] Workpiece cleaning is an important link in industrial production, which can remove impurities such as oil, dust and rust on the surface of the workpiece, and improve the quality and performance of the workpiece. The commonly used workpiece cleaning methods at present include spray cleaning, immersion cleaning and laser cleaning. The traditional workpiece cleaning method has the following problems:

[0003] (1) It cannot automatically adjust the cleaning parameters such as temperature, pressure and time according to different types, sizes, shapes and surface cleanliness of the workpiece, resulting in poor cleaning effect or waste of resources;

[0004] (2) It cannot automatically adjust the cleaning liquid treatment mode according to different types, sizes, shapes and surface cleanliness of the workpiece, resulting in unstable performance of the cleaning liquid or unsuitability for the workpiece;

[0005] (3) It cannot detect and feedback the degree of contamination on the surface of the workpiece, resulting in overcleaning or insufficient cleaning.

[0006] For example, the workpiece cleaning method and cleaning system disclosed in Chinese Patent Publication No. CN116871231A use image processing and fuzzy logic technology to identify the characteristics of the workpiece and set the cleaning parameters; use genetic algorithm technology to optimize the control of the cleaning liquid circulation module; and use cleanliness detection technology to feedback and adjust the cleaning effect. This feature uses image acquisition and image processing technology to obtain image data of the workpiece through shooting and scanning technology; processes the image data through preprocessing and feature extraction technology to obtain characteristic data of the workpiece; and analyzes the characteristic data through classification technology to obtain information such as the type, size and shape of the workpiece. There is also a workpiece cleaning method disclosed in Chinese Patent Publication No. CN115488107A, which fixes the workpiece to be cleaned and determines the focal length of the laser output beam on the surface of the workpiece to be cleaned, then controls the laser to output laser beams on the first cleaning surface according to different output parameters for at least two times of scanning ablation, flips the workpiece to be cleaned so that the second cleaning surface of the workpiece to be cleaned faces the laser, then controls the laser to output laser beams on the second cleaning surface according to different output parameters for at least two times of scanning ablation, and flips the workpiece to obtain the cleaned workpiece.

[0007] In the above cleaning, when there are differences between workpieces, it is time-consuming and laborious to manually set the path, and the commonly used convolutional neural network algorithm needs a large amount of data and workpiece information, and manual intervention is still required in workpiece processing.

[0008] Further, a workpiece cleaning method disclosed in Chinese Patent Publication No. CN108284107A, a working gas is introduced into the plasma generator, and the gas in the plasma generator is extracted, so that the gas pressure in the plasma generator is within a preset range; the power supply is started, the working gas remaining in the plasma generator is discharged to generate plasma to clean the workpiece to be cleaned; after a preset time, air is introduced into the plasma generator to restore the internal pressure of the plasma generator. The workpiece cleaning method provided by the application can avoid waste water and reduce environmental pollution.

[0009] The above cleaning system is based on water washing, and feature extraction is completed by image data of the workpiece to obtain the type, size and shape of the workpiece. When the workpiece is large or has special-shaped surfaces, stepped shafts and too many features, the feature extraction result is too much, which increases the possibility of conflict in cleaning decision, and when the above cleaning system does not select a suitable cleaning path combined with the features of the workpiece, the cleaning path can only be manually set, and the control has the problems of large manual cost and incomplete standardization. SUMMARY

[0010] To solve the above technical problems, the application provides a laser cleaning path automatic planning method and a laser cleaning device.

[0011] The technical scheme adopted by the application is a laser cleaning path automatic planning method, the method comprising the following steps:

[0012] S1 obtaining three-dimensional information of a workpiece to be cleaned;

[0013] S2 planning a cleaning path based on the three-dimensional information to obtain a partition cleaning strategy of the workpiece to be cleaned;

[0014] S3 configuring galvanometer adjustment information of a laser cleaning device corresponding to the partition cleaning strategy;

[0015] S4 controlling the laser cleaning device to clean the workpiece to be cleaned according to the planned partition cleaning strategy, and adjusting the galvanometer in real time based on the galvanometer adjustment information to adapt to the change of the surface shape of the workpiece to be cleaned.

[0016] Preferably, in S2, the features of each preset size surface in the three-dimensional information of the workpiece to be cleaned are extracted, a set is established for each surface based on each feature, and a corresponding partition is obtained.

[0017] Preferably, the features include protrusions, recesses and flatness; a set of coordinates is established for each highest point in the partition corresponding to the protrusion feature, a set of coordinates is established for each lowest point in the partition corresponding to the recess feature, and a set of coordinates is established for each center point in the partition corresponding to the flatness feature, and a path corresponding to the minimum distance between each two coordinates is extracted as the optimal path of the partition cleaning strategy.

[0018] Preferably, in S3, configuring the galvanometer adjustment information comprises the following steps:

[0019] S3.1 Set the neighborhood radius and core radius of each partition set of the workpiece to be cleaned, and preset the adjustment angle range of the galvanometer; the laser focusing depth is best within a certain range during laser cleaning, so the core radius is set, and the focal depth requirement must be met within the core radius; the neighborhood radius includes the surrounding area of the current cleaning area, which is used to determine which adjacent area to clean next in the optimal path determination method; based on the adjustment angle of the galvanometer, the change range of the normal vector in the post-partition area is determined, and for the adjacent same feature surface, even if it may have a certain fluctuation, as long as it belongs to the same feature, it is fused;

[0020] S3.2 Calculate the normal vector of the points in the partition based on the preset parameters as the partition determination basis; obviously, the points in the partition of the flatness feature do not need to be calculated;

[0021] S3.3 Filter the calculated normal vectors according to the preset angle range, delete the points whose included angle with the Z-axis is not within the preset adjustment angle range of the galvanometer, and the Z-axis is the vertical axis; the cleaning of the range corresponding to the filtered points can be realized by secondary cleaning;

[0022] S3.4 Plan the optimal galvanometer motion information in combination with the partition cleaning strategy.

[0023] A laser cleaning device using the laser cleaning path automatic planning method, the device comprises:

[0024] a base;

[0025] a position transfer unit arranged on the base and used for realizing the position movement of the device except the base;

[0026] a three-dimensional scanning and constructing unit arranged at the output end of the position transfer unit and used for scanning the workpiece to be cleaned and constructing the three-dimensional information of the workpiece;

[0027] a laser cleaning unit arranged at the output end of the three-dimensional scanning and constructing unit and used for laser cleaning of the workpiece to be cleaned;

[0028] The position transfer unit, the three-dimensional scanning and constructing unit and the laser cleaning unit are matched with a controller.

[0029] Preferably, the position transfer unit comprises a planar stroke control mechanism arranged on the base and a longitudinal stroke control mechanism arranged on the planar stroke control mechanism, an output end of the longitudinal stroke control mechanism is arranged in cooperation with the three-dimensional scanning and building unit through a first steering joint, and the first steering joint is arranged in cooperation with the controller.

[0030] Preferably, a second steering joint is arranged between the three-dimensional scanning and building unit and the laser cleaning unit, and the second steering joint is arranged in cooperation with the controller.

[0031] Preferably, a long-focus depth lens is arranged in cooperation with the laser cleaning unit, and a focal length f and a beam diameter w0 of the long-focus depth lens satisfy f > f0 and w0 < w00 respectively, wherein f0 is a preset reference focal length, and w00 is a preset reference spot diameter.

[0032] The present application relates to a laser cleaning path automatic planning method and a laser cleaning device, three-dimensional information of a workpiece to be cleaned is obtained, a cleaning path is planned and a partition cleaning strategy of the workpiece to be cleaned is obtained, mirror adjustment information of a laser cleaning device is configured, the laser cleaning device is controlled to clean the workpiece to be cleaned according to the planned partition cleaning strategy, and the mirror is adjusted in real time based on the mirror adjustment information to adapt to the change of the surface shape of the workpiece to be cleaned; the device comprises a base, a position transfer unit realizes the position movement of the device except the base, an output end of the position transfer unit is provided with a three-dimensional scanning and building unit for scanning the workpiece to be cleaned and building three-dimensional information of the workpiece, and finally the workpiece to be cleaned is cleaned by a laser cleaning unit.

[0033] The present application has the following beneficial effects:

[0034] (1) The type, size and shape of the workpiece are quickly obtained by scanning, and the cleaning path is automatically planned based on interference analysis according to the obtained three-dimensional model, so that the cleaning efficiency is improved, and the intelligent selection of the cleaning path and the cleaning strategy is completed;

[0035] (2) The path is verified according to the selection result, so that the workpiece is prevented from being hit due to cleaning failure or motion interference;

[0036] (3) The three-dimensional model is disassembled to obtain a plurality of partitions, the connection path between each partition in the uncleaned area is established, the connection path of all partitions is connected, the path of the uncleaned area is combined with the path of the to-be-cleaned area, the entire path planning of the workpiece to be cleaned is obtained, the redundancy and repetition of the cleaning path are reduced, the cleaning efficiency is improved, the loopholes of the cleaning work are reduced, and the completeness and comprehensiveness of the cleaning are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The method flowchart of the present application is shown in the figure;

[0038] Figure 2 A schematic diagram of a partition cleaning strategy in the present application;

[0039] Figure 3 A schematic diagram of a laser cleaning device structure in the present application. DETAILED DESCRIPTION

[0040] The present application will be further described in conjunction with the embodiments below, but the scope of protection of the present application is not limited thereto.

[0041] As Figure 1 shown, the present application relates to a laser cleaning path automatic planning method, which comprises the following steps:

[0042] S1 obtains three-dimensional information of a workpiece to be cleaned;

[0043] S2 plans a cleaning path based on the three-dimensional information to obtain a partition cleaning strategy for the workpiece to be cleaned;

[0044] S3 configures galvanometer adjustment information of a laser cleaning device corresponding to the partition cleaning strategy;

[0045] S4 controls the laser cleaning device to clean the workpiece to be cleaned according to the planned partition cleaning strategy, and adjusts the galvanometer in real time based on the galvanometer adjustment information to adapt to the change of the surface shape of the workpiece to be cleaned.

[0046] Each step is described in detail below.

[0047] In S1, a three-dimensional model of the workpiece needs to be established before laser cleaning, which is generally completed by setting a scanning mechanism or similar device.

[0048] In this embodiment, a plurality of cameras and a processor are used to collect two-dimensional pictures of the workpiece to be cleaned from different angles. These images can be color images or depth images. The processor is used to process the collected two-dimensional pictures, which specifically comprises the following steps:

[0049] S1.1 confirms the internal parameters of the camera, such as focal length and principal point coordinates, and confirms the external parameters of the camera, such as the position and direction of the camera, which is usually completed through a camera calibration process, and a specific calibration board or an object with a known size can be used for calibration;

[0050] S1.2 extracts feature points in each image, including but not limited to corner points, edge points, etc., and tries to match these feature points between different images to determine the corresponding relationship of the same space point in different images;

[0051] S1.3 uses the matched feature points and camera parameters to calculate three-dimensional point cloud data through triangulation or other methods to obtain some discrete points on the surface of the workpiece;

[0052] S1.4 generating a three-dimensional mesh model of the workpiece based on the calculated point cloud data;

[0053] S1.5 further optimizing and processing the generated three-dimensional model, such as removing noise, filling holes, smoothing surfaces, etc., to improve the quality of the model.

[0054] In S1.3, the projection equation of the i-th camera is,

[0055]

[0056] where i is the serial number of the camera, P i is the projection matrix of the i-th camera, K i is the internal parameter matrix of the i-th camera, [P i , t i ] is the external parameter matrix;

[0057] The three-dimensional point coordinates of the workpiece feature points are X i = [x, y, z, 1] T , then the image coordinates of the projection at the i-th view angle are: It can be obtained that,

[0058]

[0059] That is,

[0060] x i (p i3 X)-p i1 X = 0

[0061] y i (p i3 X)-p i2 X = 0

[0062] x i (p i2 X)-y i (p i1 X) = 0

[0063] Solving the three equations simultaneously gives the matrix equation,

[0064]

[0065] Given X = [x i , y i , z i , 1] T , the degree of freedom of X is 3, it can be known that one view angle of the projection of X point can provide two constraints, and at least two or more view angles are needed to solve the three-dimensional coordinates of X. If there are N view angles of image projection coordinates of the same three-dimensional point X, then the least squares method is used to solve.

[0066] In S2, the features of each preset size face in the three-dimensional information of the workpiece to be cleaned are extracted, and a set is established for each face based on each feature, respectively, to obtain a corresponding partition, the convex set is recorded as T=[t1, t2, … t n ], the concave set is recorded as A=[a1, a2, … a n ], and the flat set is recorded as P=[p1, p2, … p n ].

[0067] The features include convex, concave and flat;

[0068] In the specific implementation process, the judgment method of convex, concave and flat is:

[0069] Taking the contact surface of the workpiece and the cleaning device as a reference plane, the angle θ between the normal line of each point on the surface of the workpiece and the normal line of the reference plane is calculated, when-5°≤θ≤5°, the partition is judged to be flat; when θ>5°, it is judged to be convex; when θ<-5°, it is judged to be concave; in actual application, the partition generally corresponds to the cleaning range of the laser cleaning head;

[0070] A coordinate set is established for each highest point in the partition set T corresponding to the convex feature, a coordinate set is established for each lowest point in the partition set A corresponding to the concave feature, and a coordinate set is established for each center point in the partition set P corresponding to the flat feature, and the path corresponding to the minimum distance between each two coordinates is extracted, that is, the nearest value of the coordinates in T to A, T to P, and A to P is calculated as the optimal path of the partition cleaning strategy.

[0071] In the present application, path verification is also needed; in the specific implementation process, the path verification is to import the three-dimensional model, set the laser cleaning focal depth, laser power, laser spot diameter and other parameters in the laser cleaning device through the three-dimensional model, and judge whether each partition cleaning is successful according to the maximum moving threshold and actual movement of each point of the given laser cleaning device.

[0072] In S3, the configuration of the galvanometer adjustment information includes the following steps:

[0073] S3.1 sets the neighborhood radius and core radius of each partition set of the workpiece to be cleaned, and presets the adjustment angle range of the galvanometer; here, the neighborhood radius is used to determine the range of points participating in the calculation of the normal vector, and the core radius is used to define the core area in the calculation process, in which area the laser head does not change position during cleaning, and only rotation within the core radius can achieve cleaning; in actual application, the neighborhood radius is consistent with the step length;

[0074] S3.2 calculates the normal vector of the points in the partition based on the preset parameters as the partition judgment basis;

[0075] S3.3 filtering the calculated normal vector according to a preset angle range, and deleting points whose included angle with the Z axis is not within the preset angle range of the galvanometer;

[0076] S3.4 planning optimal galvanometer motion information in combination with a partition cleaning strategy.

[0077] As shown in Figure 2 , an embodiment is given;

[0078] a is the core radius, and b and c correspond to the neighborhood radius;

[0079] When partitioning, define the A region in the graph as concave, the B region as flat, and the C region as convex;

[0080] Partitioning as A, paths on the same concave, convex, and flat feature surface can be cleaned in order (such as S-shaped), and for paths crossing regions, as shown by points 1 and 2 in the figure, horizontal motion displacement and vertical lifting height are considered, and the path with the shortest motion is selected.

[0081] In the present application, high-power laser has a smaller spot, and a larger spot can effectively cover more areas, therefore, the angle adjustment range of the galvanometer needs to meet the precise focal length adjustment requirement, specifically, the angle range of the galvanometer is between ±10° and ±20°;

[0082] Further, the present application also tends to select a long focal depth lens as part of the laser cleaning device, which has a large focal depth to adapt to workpieces of different surface heights, and in the laser cleaning process, the focal length and beam diameter of the long focal depth lens are adjusted to maintain the focusing effect between different surface heights, avoiding uneven surface treatment or defocusing due to too small focal depth.

[0083] As shown in Figure 3 , the present application also relates to a laser cleaning device using the laser cleaning path automatic planning method, and the device comprises:

[0084] a base 500;

[0085] a position transfer unit arranged on the base 500 and used for realizing position movement of the device except the base 500;

[0086] a three-dimensional scanning and constructing unit 100 arranged at the output end of the position transfer unit and used for scanning a workpiece to be cleaned and constructing three-dimensional information of the workpiece;

[0087] a laser cleaning unit 400 arranged at the output end of the three-dimensional scanning and constructing unit 100 and used for laser cleaning of the workpiece to be cleaned;

[0088] The position transfer unit, the three-dimensional scanning and building unit 100 and the laser cleaning unit 400 are provided with a controller.

[0089] Specifically, the position transfer unit comprises a planar stroke control mechanism 200 arranged on the base 500 and a longitudinal stroke control mechanism 300 arranged on the planar stroke control mechanism 200, an output end of the longitudinal stroke control mechanism 300 is arranged in cooperation with the three-dimensional scanning and building unit 100 through a first steering joint, the first steering joint is arranged in cooperation with the controller; a second steering joint is arranged between the three-dimensional scanning and building unit 100 and the laser cleaning unit 400, the second steering joint is arranged in cooperation with the controller; the cooperation between the planar stroke control mechanism 200 and the longitudinal stroke control mechanism 300 and the base 500, and the arrangement of the first steering joint and the second steering joint are easy to understand for those skilled in the art, and those skilled in the art can arrange them according to requirements.

[0090] The laser cleaning unit 400 is provided with a long focal depth lens, the focal length f and the beam diameter w0 of the long focal depth lens respectively satisfy f > f0 and w0 < w00, wherein f0 is a preset reference focal length, and w00 is a preset reference spot diameter; in actual application, generally, f0 = 150 mm and w0 = 5 mm are arranged.

[0091] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can adopt a completely hardware embodiment, a completely software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can adopt a computer program product implemented on one or more computer usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer usable program codes.

[0092] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device for realizing the functions specified in the flowcharts and / or block diagrams. Figure 1 The device for realizing the functions specified in one flow or multiple flows and / or blocks Figure 1 The device for realizing the functions specified in one flow or multiple flows and / or blocks

[0093] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0094] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0095] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the embodiments by those skilled in the art once they learn of the basic inventive concepts. Therefore, the appended claims are intended to cover all such modifications and variations as fall within the true spirit and scope of the application.

[0096] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for automatic laser cleaning path planning, characterized in that: The method includes the following steps: S1 acquires the three-dimensional information of the workpiece to be cleaned; S2 extracts features of each preset-size facet from the 3D information of the workpiece to be cleaned. The features include protrusions, depressions, and flatness. Each facet is set based on each feature to obtain a corresponding partition. A cleaning path is planned based on the 3D information to obtain a partition cleaning strategy for the workpiece to be cleaned. A coordinate set is established for each highest point in the partition corresponding to the protrusion feature, a coordinate set is established for each lowest point in the partition corresponding to the depression feature, and a coordinate set is established for each center point in the partition corresponding to the flatness feature. The path corresponding to the minimum distance between each pair of coordinates is extracted as the optimal path of the partition cleaning strategy. S3 configures the galvanometer adjustment information of the laser cleaning equipment according to the partition cleaning strategy; the focal length f and beam diameter w0 of the long focal depth lens satisfy f > f0 and w0 < w00 respectively, where f0 is the preset reference focal length and w00 is the preset reference spot diameter. S4 controls the laser cleaning equipment to clean the workpiece according to the planned zoned cleaning strategy, and adjusts the galvanometer in real time based on the galvanometer adjustment information to adapt to changes in the surface shape of the workpiece.

2. The automatic laser cleaning path planning method according to claim 1, characterized in that: In S3, configuring galvanometer adjustment information includes the following steps: S3.1 Set the neighborhood radius and core radius of each partition set of the workpiece to be cleaned, and preset the adjustment angle range of the galvanometer; S3.2 Based on preset parameters, as the basis for partitioning, calculate the normal vector of the points in the partition; S3.3 Filter the calculated normal vector according to the preset angle range and delete points where the angle between the normal vector and the Z-axis is not within the preset adjustment angle range of the galvanometer; S3.4 Combines the partition cleaning strategy to plan the optimal galvanometer motion information.

3. A laser cleaning apparatus employing the automatic laser cleaning path planning method according to any one of claims 1 to 2, characterized in that: The device includes: A base; A position transfer unit, mounted on the base, is used to realize the position movement of the device other than the base; A three-dimensional scanning and construction unit is located at the output end of the position transfer unit and is used to scan the workpiece to be cleaned and construct the three-dimensional information of the workpiece. A laser cleaning unit is located at the output end of the 3D scanning construction unit and is used to perform laser cleaning on the workpiece to be cleaned. A controller is provided to work in conjunction with the position transfer unit, the three-dimensional scanning construction unit, and the laser cleaning unit.

4. The laser cleaning apparatus according to claim 3, characterized in that: The position transfer unit includes a planar stroke control mechanism mounted on the base and a longitudinal stroke control mechanism mounted on the planar stroke control mechanism. The output end of the longitudinal stroke control mechanism is configured to cooperate with the three-dimensional scanning construction unit through a first steering knuckle, and the first steering knuckle is configured to cooperate with the controller.

5. The laser cleaning apparatus according to claim 4, characterized in that: A second steering knuckle is provided between the 3D scanning construction unit and the laser cleaning unit, and the second steering knuckle is configured in conjunction with the controller.

6. The laser cleaning apparatus according to claim 3, characterized in that: The laser cleaning unit is equipped with a long focal depth lens, the focal length f and the beam diameter w0 of which satisfy f > f0 and w0 < w00, respectively, where f0 is a preset reference focal length and w00 is a preset reference spot diameter.

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