CN114022370B - Galvanometer laser processing distortion correction method and system - Google Patents
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Abstract
The invention discloses a method and a system for correcting laser processing distortion of a galvanometer, wherein the method comprises the following steps: manufacturing a calibration characteristic pattern by adopting a round filling and marking mode; traversing the contours in the obtained galvanometer laser processing image to obtain the minimum enveloping circle of each contour, and screening the minimum enveloping circle with the circle radius meeting the requirement to obtain a calibration characteristic pattern; obtaining the actual coordinates of the calibration feature points according to the circle center coordinates of the minimum enveloping circle in the calibration feature patterns; and obtaining a correction error according to the actual coordinate and the ideal coordinate of the calibration characteristic point, and carrying out distortion correction according to the correction error. The circle filling marking method is adopted to replace the existing point array or cross array marking scheme, the machine vision identification is adopted to replace manual measurement to obtain distortion errors, the minimum enveloping circle detection method is adopted to replace the existing point detection or line detection, the sensitivity to processing defects and visual noise is reduced, the anti-interference capability is enhanced, the correction precision and efficiency are improved, and the automation degree, the integration level and the flexibility are improved.
Description
Technical Field
The invention relates to the technical field of galvanometer laser processing, in particular to a galvanometer laser processing distortion correction method and system.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The laser processing of the vibrating mirror is a novel laser processing mode, the light path is changed through the small-range quick deflection of the vibrating mirror, the quick positioning of a light beam focus point in a large range is realized, and the flexibility and the efficiency of the laser processing are greatly improved. The galvanometer laser processing is widely applied to the high-end processing fields of aerospace, automobiles, ships, precise electronics and the like, has wide development prospect, and typical application scenes comprise laser scanning welding, laser flight welding, laser surface micro-texture processing, laser quenching, laser cleaning and the like.
Galvanometer laser processing faces the problem of distortion of the processed pattern. The pattern distortion can be decomposed into two components, barrel distortion in the X direction and pincushion distortion in the Y direction. The distortion is typically caused by a superposition of factors including simplification of the control strategy, manufacturing assembly errors of the mechanical or optical structures, variations in ambient temperature, friction and vibration, etc. The figure distortion influences the positioning precision and the processing quality of the galvanometer, the distortion is eliminated in the actual operation process by usually adopting a mode of firstly measuring errors and then compensating and correcting, and the compensation algorithm comprises two types of high-order curve fitting and array linear interpolation.
The traditional method for acquiring the machining error is manual measurement, and the measurement method has the disadvantages of large error, low precision, low efficiency, high labor cost and time cost, and is not beneficial to large-scale application and popularization. The adoption of machine vision instead of human eye observation for feature recognition and error acquisition is a popular research direction and production trend in recent years, and some achievements exist at present. One way is to obtain the mark point image by line scanning, and the way needs to equip a special servo mobile station and a control system for the sensor to form complete plane mark point information, so that the cost is higher and the efficiency is lower; one method is to manufacture a standard diaphragm plate, compare and analyze the difference between a standard pattern and an actual marked pattern by a covering method, which has high requirements on the manufacturing precision and materials of the diaphragm plate and depends on the positioning accuracy during covering, thereby bringing disadvantages in cost and operability; one method is to mark equal grid or dot array or cross mark array on the photosensitive material, and to extract information directly by characteristic identification, and this marking and identification detection scheme is susceptible to track fluctuation, line thickness variation, line breakage, burning through, noise and other defects in the marking process, and has high requirements for laser marking process, laser light quality and camera performance, poor system stability and limited application range.
In summary, for the figure distortion of galvanometer laser processing, how to reasonably select a marking, identifying and detecting scheme, how to optimize a vision processing algorithm, how to ensure the stability of a system while improving the distortion correction precision and efficiency, and an effective solution is not yet available.
Disclosure of Invention
In order to solve the problems, the invention provides a galvanometer laser processing distortion correction method and a galvanometer laser processing distortion correction system, wherein a circle filling marking method is adopted to replace the existing point array or cross array marking scheme, machine vision identification is adopted to replace manual measurement to obtain distortion errors, a minimum enveloping circle detection method is adopted to replace the existing point detection or line detection, the sensitivity to processing defects and visual noise points is reduced, the anti-interference capability is enhanced, the correction precision and efficiency are improved, and the automation degree, the integration degree and the flexibility are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a galvanometer laser processing distortion correction method, including:
manufacturing a calibration characteristic pattern by adopting a round filling and marking mode;
traversing the contours in the obtained galvanometer laser processing image to obtain the minimum enveloping circle of each contour, and screening the minimum enveloping circle with the circle radius meeting the requirement to obtain a calibration characteristic pattern;
obtaining the actual coordinates of the calibration feature points according to the circle center coordinates of the minimum enveloping circle in the calibration feature patterns;
and obtaining a correction error according to the actual coordinate and the ideal coordinate of the calibration characteristic point, and carrying out distortion correction according to the correction error.
As an alternative embodiment, the obtaining process of the calibration feature pattern includes: and presetting the minimum value of the circle radius, and deleting the abnormal minimum enveloping circle with the circle radius smaller than the minimum value of the circle radius according to the comparison between the circle radius and the minimum value of the circle radius.
As an alternative implementation, after the calibration feature pattern is obtained, the center of the minimum enveloping circle is the calibration feature point; after the calibration characteristic points are obtained, comparing the number of the calibration characteristic points with the filling circle array scale, and carrying out the next step after the number of the calibration characteristic points is equal to the filling circle array scale; the filled circle array scale is the circle array scale filled in the calibration feature pattern.
As an alternative embodiment, the process of acquiring the actual coordinates of the calibration feature points is as follows: after the calibration characteristic pattern is obtained, the circle center of the minimum enveloping circle is the calibration characteristic point; carrying out coordinate sequencing on the calibration characteristic points, taking four error-free points far away from the origin on the XY coordinate axis as positioning points, and establishing a homography matrix according to the corresponding relation between the pixel coordinates and the galvanometer coordinates; and after the calibration characteristic points are subjected to perspective transformation by adopting a homography matrix, converting the pixel coordinates into galvanometer coordinates to obtain actual coordinates of the calibration characteristic points.
As an alternative embodiment, the distortion correction of the point to be compensated according to the correction error by using a high-order curve fitting compensation algorithm includes:
in the formula, (X, Y) is the coordinate of the point to be compensated, Δ X is the error of the point to be compensated in the X direction, and Δ Y is the error of the point to be compensated in the Y direction; a is 1 ～a 4 、b 1 ～b 4 Fitting coefficients for the four quadrants, respectively.
As an alternative embodiment, the distortion correction of the point to be compensated according to the correction error by using an array linear interpolation compensation algorithm includes:
wherein (X, Y) is the coordinate of the point to be compensated, Δ X is the error of the point to be compensated in the X direction, Δ Y is the error of the point to be compensated in the Y direction, X 1 、x 2 、y 1 、y 2 Respectively the value of the interpolation grid unit in the X direction and the value of the interpolation grid unit in the Y direction, dx 1 ～dx 2 、dy 1 ～dy 2 The four corner errors of the interpolation grid unit where the point to be compensated is located are respectively.
As an alternative embodiment, the galvanometer laser processing distortion correction method further includes: after distortion correction is finished, measuring the corrected galvanometer processing precision through a standardized dot matrix, setting a calibration point array in a processing plane range, and obtaining errors of each calibration point in the X direction and the Y direction according to the coordinates of the calibration point to form a standardized precision calibration table; and carrying out standardized dot matrix calibration on the corrected galvanometer laser processing system to obtain the corrected maximum error, average error and distribution of the error in a processing plane, and optimizing the correction process on the basis of the maximum error, the average error and the distribution.
In a second aspect, the present invention provides a galvanometer laser machining distortion correction system, comprising:
the calibration characteristic pattern making module is configured to make a calibration characteristic pattern in a round filling and marking mode;
the minimum enveloping circle detection module is configured to traverse the contours in the acquired galvanometer laser processing image to obtain a minimum enveloping circle of each contour, and screen the minimum enveloping circle with a circle radius meeting the requirement to obtain a calibration characteristic pattern;
the characteristic point coordinate acquisition module is configured to obtain actual coordinates of the calibration characteristic points according to the center coordinates of the minimum enveloping circle in the calibration characteristic pattern;
and the correction module is configured to obtain a correction error according to the actual coordinates and the ideal coordinates of the calibration characteristic points, and perform distortion correction according to the correction error.
In a third aspect, the present invention provides an electronic device comprising a memory and a processor, and computer instructions stored on the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method of the first aspect is performed.
In a fourth aspect, the present invention provides a computer readable storage medium for storing computer instructions which, when executed by a processor, perform the method of the first aspect.
Compared with the prior art, the invention has the beneficial effects that:
in the galvanometer laser processing distortion correction method and system provided by the invention, machine vision identification is adopted to replace manual measurement to obtain distortion errors, the flexibility and the automation degree are higher, the integration level with a processing control system and a process system is higher, the precision grade of data is improved, and the labor cost and the time cost of distortion correction are reduced.
In the galvanometer laser processing distortion correction method and system provided by the invention, the marking process and the visual identification detection algorithm are comprehensively considered, the existing point array or cross array marking scheme is replaced by the round filling marking method, the processing range is expanded from a line to a surface area, the tolerance to processing defects is improved, the flexibility of the distortion correction system is higher, the sensitivity to the processing defects and visual noise points is reduced, and the anti-interference capability is enhanced.
In the galvanometer laser processing distortion correction method and system provided by the invention, the circle filling marking method is adopted, the recognition algorithm is optimized, the existing point detection or line detection is replaced by the minimum enveloping circle detection method, and the corresponding actual processing coordinate of the characteristic point can be accurately obtained by calculating the center coordinate of the enveloping circle.
In the method and the system for correcting the distortion of the laser processing of the galvanometer, the method for testing and evaluating the distortion of the laser processing image of the galvanometer is adopted, and a standardized filling circle array calibration mode is adopted to be matched with visual identification, so that the precision distribution in a processing breadth range can be conveniently obtained, the error description of the galvanometer is unified and simplified, and the evaluation and the comparison of the correction effect are convenient.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
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The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a flowchart of correcting distortion in laser processing of a galvanometer according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the distortion of the galvanometer provided in embodiment 1 of the present invention;
FIG. 3 is a flowchart of a visual identification detection algorithm provided in embodiment 1 of the present invention;
fig. 4(a) -4(b) are schematic diagrams of interpolation grid units provided in embodiment 1 of the present invention;
FIG. 5 is a graph of normalized accuracy measurements provided in example 1 of the present invention;
FIGS. 6(a) -6(c) are uncorrected standard measurement patterns and X Y direction-corrected error profiles provided in example 1 of the present invention;
FIGS. 7(a1) -7(c6) are graphs of the standard measurement lattices after 6 calibration experiments and the corrected error distribution in the XY direction provided in example 1 of the present invention;
fig. 8 is a statistical error chart of experimental verification provided in embodiment 1 of the present invention.
Detailed Description
The invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and it should be understood that the terms "comprises" and "comprising", and any variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
Example 1
The embodiment provides a galvanometer laser processing distortion correction method, in particular to a galvanometer distortion identification detection and deviation correction method based on machine vision, which improves distortion correction precision and efficiency and ensures system stability. The implementation process mainly comprises the following steps: the method comprises the steps of processing a calibration characteristic pattern, visually identifying and detecting calibration characteristic points, obtaining coordinates of the calibration characteristic points, constructing a correction error table, executing a compensation correction algorithm and measuring the corrected precision.
As shown in fig. 1, the method specifically comprises the following steps:
s1: manufacturing a calibration characteristic pattern by adopting a round filling and marking mode;
s2: traversing the contours in the obtained galvanometer laser processing image to obtain the minimum envelope circle of each contour, and screening the minimum envelope circles with the circle radius meeting the requirement to obtain a calibration characteristic pattern;
s3: obtaining the actual coordinates of the calibration feature points according to the circle center coordinates of the minimum enveloping circle in the calibration feature patterns;
s4: and obtaining a correction error according to the actual coordinate and the ideal coordinate of the calibration characteristic point, and carrying out distortion correction according to the correction error.
In the step S1, the existing calibration feature pattern adopts an equally divided grid, a dot array or a cross mark array, which are all single line calibration, and are prone to generating processing defects. For example, over burning and burn-through are caused by acceleration and deceleration processes, line thickness variation or line breakage is caused by laser power fluctuation, line track fluctuation is caused by factors such as mechanical friction and the like. For manual measurement, the requirement on marking quality is not high; however, for visual identification, the marking quality directly affects the identification success rate and stability, and the processing defects weaken the characteristic information and cause false identification.
Therefore, the round filling marking mode is adopted to replace single-line marking, the processing range is expanded from a line to a surface area, the tolerance of the processing defects is improved, and the interference of the defects is avoided to the greatest extent. Correspondingly, the recognition algorithm is optimized, the existing point detection or line detection is replaced by the minimum enveloping circle detection method, and the corresponding actual processing coordinates of the feature points can be accurately obtained by calculating the coordinates of the circle center of the enveloping circle.
The corresponding relation between the mechanical rotation angle of the galvanometer and a coordinate point in a processing plane is a complex nonlinear relation, and at present, in order to reduce the calculation amount and improve the real-time performance of a system, a simplified linear relation is generally adopted for replacing the corresponding relation, so that the generated error is the main reason for generating the distortion of a laser processing graph of the galvanometer.
The theoretical relationship between the actual coordinate point and the ideal coordinate point is as follows:
where (x, y) is the ideal point coordinates, (x ', y') is the actual machining coordinates, and f is the field flattener focal length.
Therefore, the method for constructing the galvanometer laser processing error estimation model comprises the following steps:
where Δ X is the error of the point in the X direction and Δ Y is the error of the point in the Y direction.
This gives: when the coordinate point is on the X axis or the Y axis, i.e., X is 0 or Y is 0, X 'is X and Y' is Y, i.e., when the coordinate point error is zero, there is no pattern distortion.
The error estimation model can perform off-line simulation operation under ideal conditions on a software level, predict the correction effect of the correction algorithm and visually display the correction effect, and timely adjust the algorithm parameters or optimize the algorithm details under the condition of insufficient correction so as to achieve good compensation effect.
In this embodiment, the calibration feature pattern is composed of simple primitives, such as a filled circle array, as shown in FIG. 2, and the pattern processing is not corrected for distortion and contains coordinate error information. As known from the error estimation model, the coordinate point error of the uncorrected pattern on the axis is zero, which can represent an ideal position, so that the coordinate difference between a point not on the axis and its projected point on two coordinate axes is its error in both directions of the X-axis and the Y-axis, i.e. the X-component and the Y-component of the pattern distortion. Therefore, in the embodiment, the feature point coordinates are obtained through visual identification and calculation, and each feature point error or correction parameter required by the correction compensation control algorithm can be calculated, so as to construct a correction error table.
In the step S3, in the conventional galvanometer distortion correction, the coordinate point measurement work is manually completed and is input into the processing system one by one as a parameter, so that the process is complicated, the efficiency is low, and errors are prone to occur; and the distortion correction of the galvanometer is a necessary step before the laser galvanometer is processed, and a correction result can be repeatedly used for a plurality of times without adjusting the height of the galvanometer lens, so that the actual utilization rate of a special correction platform (linear scanning) or correction equipment (a standard diaphragm plate) designed in the prior art is not high, but the use cost is high, thereby causing waste.
Therefore, the method for calibrating the vibration mirror laser processing image based on the visual recognition obtains the vibration mirror laser processing image by means of the general industrial camera, detects the minimum enveloping circle by means of the visual recognition method, obtains the calibration characteristic patterns in the vibration mirror laser processing image, and recognizes and detects coordinates of each calibration characteristic point.
In this embodiment, as shown in fig. 3, after an original image shot by an industrial camera is obtained, preprocessing is performed on the image, including gaussian filtering to eliminate noise points, and canny operator edge detection to obtain a contour;
traversing the contours to obtain the minimum enveloping circle of each contour;
and presetting the minimum value of the circle radius, and deleting the abnormal minimum enveloping circle with the circle radius smaller than the minimum value of the circle radius according to the comparison between the circle radius and the minimum value of the circle radius.
In step S3, after the calibration feature pattern is separated, the set of circle centers of the minimum enveloping circles is the set of calibration feature points;
preferably, traversing the minimum enveloping circle, removing the abnormal circle, combining circles with approximate circle center positions, namely, averaged coordinates and radius, combining the circles with the circle center distances smaller than the distance threshold value in a mode of setting the distance threshold value, wherein all the circle centers after the step are the identified feature point set.
Preferably, after the calibration characteristic points are obtained, comparing the number of the calibration characteristic points with the filling circle array scale, and if the number of the calibration characteristic points is equal to the filling circle array scale, performing the next step; otherwise, if the missing detection or the false detection exists, returning to the initial step.
Preferably, the array of filled circles is of size n x n, where n is the number of filled circles in a row or column.
In this embodiment, the process of acquiring the actual coordinates of the calibration feature points is as follows: after the calibration characteristic points are obtained, coordinate sorting is carried out on the calibration characteristic points, and the point sequence corresponds to the point sequence in actual calibration;
taking four error-free points far away from the center on the XY coordinate axis as positioning points, and establishing a homography matrix according to the corresponding relation between the pixel coordinate and the galvanometer coordinate;
and (4) carrying out perspective transformation on all the calibrated characteristic points by adopting a homography matrix, correcting the shooting angle deviation of the camera and converting the pixel coordinates into galvanometer coordinates.
In step S4, a correction error table is obtained according to the difference between the actual galvanometer coordinate and the ideal galvanometer coordinate, and the error compensation is performed on the galvanometer position according to the compensation mode to complete the distortion correction.
In this embodiment, after obtaining the errors of the feature points, the error distribution in the processing breadth range needs to be calculated, and since the arrangement density of the feature points cannot be too high, the regional errors between the feature points can only be calculated from the known errors of the feature points through an interpolation algorithm.
Therefore, by analyzing the correction error table, the error amount of the current position is calculated by an interpolation algorithm in each galvanometer control period according to the correction compensation algorithm and parameters, and the coordinate value of the galvanometer position is compensated before the next galvanometer position, so that the purpose of eliminating the processing distortion is achieved.
The correction compensation algorithm comprises a high-order curve fitting compensation algorithm and an array linear interpolation compensation algorithm. The high-order curve fitting compensation is a formula-driven compensation algorithm, the needed characteristic point coordinates are few, the calculation amount is small, and the precision is poor; the array linear interpolation compensation is a data-driven compensation algorithm, and has the advantages of more required characteristic point coordinates, higher precision, table lookup operation and lower efficiency.
In this embodiment, the high-order curve fitting compensation algorithm needs coordinates of nine feature points, and with a coordinate axis zero point and four direction points as zero error references, the errors of the four quadrant points in the two directions of X and Y are calculated respectively, and the following formula is substituted:
where (X, Y) is the coordinates of the point, Δ X is the error of the point in the X direction, and Ay is the error of the point in the Y direction; a is 1 ～a 4 、b 1 ～b 4 Respectively is the fitting coefficient of four quadrants, and a can be obtained by the coordinates and the errors of the characteristic points of the four quadrants 1 ～a 4 、b 1 ～b 4 Eight coefficients.
And in the galvanometer control period, before the galvanometer position is sent each time, the error calculation formula is called to carry out error compensation so as to correct the distortion.
In this embodiment, the array linear interpolation compensation algorithm is an interpolation method with high compensation accuracy, and the compensation accuracy is higher as the interpolation grid division is finer and the error table data is more. Taking a 9 x 9 array as an example, 81 characteristic circles are uniformly distributed in the processing breadth range, the coordinates of the circle centers are obtained, the difference between the coordinates of the corresponding projection points without error on the coordinate axis is calculated, and the point error is obtained; these error data are organized in a tabular form, and error tables in the X direction and the Y direction are constructed.
When compensating for the delivered position coordinates of the galvanometer, firstly, determining which interpolation grid unit the point is in, and as shown in fig. 4(a) -4(b), obtaining the estimation error of the current point according to the following array interpolation formula and compensating for the delivered coordinates:
where (X, Y) is the coordinates of the point, Δ X is the error of the point in the X direction, Δ Y is the error of the point in the Y direction, and X is the error of the point in the X direction 1 、x 2 、y 1 、y 2 The grid cell X direction maximum and Y direction maximum, dx, are the point 1 ～dx 2 、dy 1 ～dy 2 The errors of the four corner points of the grid unit where the point is located are respectively.
The characteristic points in the array linear interpolation are densely distributed in the processing breadth range, and the estimation close to the error true value can be obtained in the area far away from the characteristic points through interpolation, so that the method simultaneously compensates the system error and the random error, and the relationship between the correction efficiency and the correction precision can be well balanced by adjusting the arrangement scale of the characteristic points.
In this embodiment, in order to quantify the correction effect, the present embodiment further provides a mechanism for calibrating a standardized lattice of the galvanometer system, so as to measure the processing precision of the galvanometer after correction. As shown in fig. 5, 11 × 11 arrays of calibration points are uniformly distributed in the processing breadth range, coordinates of all the calibration points are obtained through visual identification and detection, errors of each calibration point in the X direction and the Y direction are calculated, and a standardized precision calibration table is formed; the corrected galvanometer system is subjected to standardized dot matrix calibration, the corrected maximum error, average error and distribution of the error in a processing plane can be obtained, and the influence of different algorithms and parameters on the correction effect can be compared through the precision key data, so that the correction algorithm and parameters are optimized according to the influence.
The embodiment provides a galvanometer distortion identification detection and deviation correction method based on machine vision, which is based on circle filling marking and minimum enveloping circle detection, provides a complete distortion correction flow of 'off-line simulation before correction-algorithm optimization in correction-effect measurement evaluation after correction', and ensures system stability while improving distortion correction precision and efficiency.
In this embodiment, the distortion correction method is verified through experiments, a galvanometer processing head used in the experiments is a PSH14 two-dimensional scanning head, and an IPG 100W pulse fiber laser is selected as a laser source. The galvanometer support adopts a marble three-axis moving platform, the position of the galvanometer can be adjusted in the XYZ three directions, the vision camera adopts a CMOS camera of Mideway vision MV-GE500M-T type, the effective pixels are 500 thousands, the image resolution is 2592 multiplied by 1944, and no auxiliary light source is provided.
The experimental variables in this embodiment are distortion correction compensation methods (parameters), other experimental variables are controlled to be unchanged in the experimental process, and correction accuracy of different methods (parameters) is transversely compared to analyze correction effects and obtain optimal parameters. The experimental variables were taken as follows: curve fitting, 3 × 3 linear interpolation, 5 × 5 linear interpolation, 7 × 7 linear interpolation, 9 × 9 linear interpolation, and 11 × 11 linear interpolation.
The experiment is divided into four steps: firstly, designing a calibration characteristic pattern and carrying out off-line simulation processing; actually processing a calibration pattern on the photographic paper; thirdly, visually identifying the feature points and constructing an error table; and fourthly, compensating and correcting the position of the galvanometer instruction, and measuring a standard dot matrix for machining errors.
And calibrating the corrected galvanometer system by adopting an error measurement standard dot matrix to obtain the precision of 11 multiplied by 11 calibration points. 6(a) -6(c) are the uncorrected standard measurement lattice and the X Y direction corrected error distribution diagram; FIGS. 7(a1) -7(c1) are the standard measurement lattice after the 3 × 3 linear interpolation correction experiment and the error distribution diagram after the XY direction correction; FIGS. 7(a2) -7(c2) are the standard measurement lattice after the curve fitting method calibration experiment and the error distribution diagram after XY direction calibration; FIGS. 7(a3) -7(c3) are the standard measurement lattice after 5 × 5 linear interpolation correction experiment and the error distribution diagram after XY direction correction; FIGS. 7(a4) -7(c4) are the standard measurement lattice after 7 × 7 linear interpolation correction experiment and the error distribution diagram after XY direction correction; FIGS. 7(a5) -7(c5) are the standard measurement lattice after the 9 × 9 linear interpolation correction experiment and the error distribution diagram after the XY direction correction; fig. 7(a6) -7(c6) are standard measurement lattices after 11 × 11 linear interpolation correction experiments and error distribution charts after XY direction correction.
Each set of experiments was repeated 5 times to obtain an average, the errors in the X and Y directions were vector-summed, and an error statistical chart was prepared using the maximum error and the average error before and after correction as evaluation variables, as shown in fig. 8, the maximum error was decreased from 1411.12 before correction to 193.58 after correction, the average error was decreased from 259.03 before correction to 36.49 after correction, and the error removal rate was 86%. The average relative precision after correction can reach 7 multiplied by 10 optimally -4 。
Example 2
The embodiment provides a galvanometer laser processing distortion correction system, including:
the calibration characteristic pattern making module is configured to make a calibration characteristic pattern in a round filling and marking mode;
the minimum enveloping circle detection module is configured to traverse the contours in the acquired galvanometer laser processing image to obtain a minimum enveloping circle of each contour, and screen the minimum enveloping circle with a circle radius meeting the requirement to obtain a calibration characteristic pattern;
the characteristic point coordinate acquisition module is configured to obtain actual coordinates of the calibration characteristic points according to the center coordinates of the minimum enveloping circle in the calibration characteristic pattern;
and the correction module is configured to obtain a correction error according to the actual coordinates and the ideal coordinates of the calibration characteristic points, and perform distortion correction according to the correction error.
It should be noted that the modules correspond to the steps described in embodiment 1, and the modules are the same as the corresponding steps in the implementation examples and application scenarios, but are not limited to the disclosure in embodiment 1. It should be noted that the modules described above as part of a system may be implemented in a computer system such as a set of computer-executable instructions.
In further embodiments, there is also provided:
an electronic device comprising a memory and a processor and computer instructions stored on the memory and executed on the processor, the computer instructions when executed by the processor performing the method of embodiment 1. For brevity, no further description is provided herein.
It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general purpose processors, digital signal processors DSP, application specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and so on. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may include both read-only memory and random access memory, and may provide instructions and data to the processor, and a portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information.
A computer readable storage medium storing computer instructions which, when executed by a processor, perform the method described in embodiment 1.
The method in embodiment 1 may be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. The software modules may be located in ram, flash, rom, prom, or eprom, registers, among other storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor. To avoid repetition, it is not described in detail here.
Those of ordinary skill in the art will appreciate that the various illustrative elements, i.e., algorithm steps, described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (7)
1. A galvanometer laser processing distortion correction method is characterized by comprising the following steps:
manufacturing a calibration characteristic pattern by adopting a round filling and marking mode;
traversing the contours in the obtained galvanometer laser processing image to obtain the minimum enveloping circle of each contour, and screening the minimum enveloping circle with the circle radius meeting the requirement to obtain a calibration characteristic pattern;
obtaining the actual coordinates of the calibration feature points according to the circle center coordinates of the minimum enveloping circle in the calibration feature patterns;
obtaining a correction error according to the actual coordinate and the ideal coordinate of the calibration characteristic point, and carrying out distortion correction according to the correction error;
the process of obtaining the calibration characteristic pattern comprises the following steps: presetting a minimum value of the circle radius, and deleting an abnormal minimum enveloping circle with the circle radius smaller than the minimum value of the circle radius according to the comparison between the circle radius and the minimum value of the circle radius;
after the calibration characteristic pattern is obtained, the circle center of the minimum enveloping circle is the calibration characteristic point;
the process of acquiring the actual coordinates of the calibration feature points comprises the following steps: after the calibration characteristic pattern is obtained, the circle center of the minimum enveloping circle is the calibration characteristic point; carrying out coordinate sequencing on the calibration characteristic points, taking four error-free points far away from the origin on the XY coordinate axis as positioning points, and establishing a homography matrix according to the corresponding relation between the pixel coordinates and the galvanometer coordinates; after perspective transformation is carried out on the calibration characteristic points by adopting a homography matrix, pixel coordinates are converted into galvanometer coordinates to obtain actual coordinates of the calibration characteristic points;
after the calibration characteristic points are obtained, comparing the number of the calibration characteristic points with the filling circle array scale, and carrying out the next step after the number of the calibration characteristic points is equal to the filling circle array scale; the filling circle array scale is the circle array scale filled in the calibration characteristic pattern;
the calibration characteristic pattern is formed by combining simple primitives, and the pattern processing is not subjected to distortion correction and contains coordinate error information; according to the error estimation model, the coordinate point error of the uncorrected pattern on the axis is zero and can represent an ideal position, so that the coordinate difference between a point which is not on the axis and the projection point on the two coordinate axes is the error of the point in the two directions of the X axis and the Y axis, namely the X component and the Y component of the figure distortion; therefore, the characteristic point coordinates are obtained through visual identification detection and calculation, and errors or correction parameters of each characteristic point required by a correction compensation control algorithm can be calculated to construct a correction error table.
2. The galvanometer laser processing distortion correction method according to claim 1, wherein the distortion correction of the point to be compensated according to the correction error by using a high-order curve fitting compensation algorithm comprises:
in the formula, (X, Y) is the coordinate of the point to be compensated, Δ X is the error of the point to be compensated in the X direction, and Δ Y is the error of the point to be compensated in the Y direction; a is 1 ～a 4 、b 1 ～b 4 Fitting coefficients for four quadrants, respectively.
3. The galvanometer laser processing distortion correction method according to claim 1, wherein performing distortion correction on the point to be compensated by using an array linear interpolation compensation algorithm according to the correction error comprises:
wherein (X, Y) is the coordinate of the point to be compensated, Δ X is the error of the point to be compensated in the X direction, Δ Y is the error of the point to be compensated in the Y direction, X 1 、x 2 、y 1 、y 2 Respectively the value of the interpolation grid unit in the X direction and the value of the interpolation grid unit in the Y direction, dx 1 ～dx 2 、dy 1 ～dy 2 The four corner errors of the interpolation grid unit where the point to be compensated is located are respectively.
4. The galvanometer laser machining distortion correction method of claim 1, further comprising: after distortion correction is finished, measuring the corrected galvanometer processing precision through a standardized dot matrix, setting a calibration point array in a processing plane range, and obtaining errors of each calibration point in the X direction and the Y direction according to the coordinates of the calibration point to form a standardized precision calibration table; and carrying out standardized dot matrix calibration on the corrected galvanometer laser processing system to obtain the corrected maximum error, average error and distribution of the error in a processing plane, and optimizing the correction process on the basis of the maximum error, the average error and the distribution.
5. A galvanometer laser machining distortion correction system, comprising:
the calibration characteristic pattern making module is configured to make a calibration characteristic pattern in a round filling and marking mode;
the minimum enveloping circle detection module is configured to traverse the contours in the acquired galvanometer laser processing image to obtain a minimum enveloping circle of each contour, and screen the minimum enveloping circle with a circle radius meeting the requirement to obtain a calibration characteristic pattern;
the characteristic point coordinate acquisition module is configured to obtain actual coordinates of the calibration characteristic points according to the center coordinates of the minimum enveloping circle in the calibration characteristic pattern;
the correction module is configured to obtain a correction error according to the actual coordinates and the ideal coordinates of the calibration characteristic points and perform distortion correction according to the correction error;
the process of obtaining the calibration characteristic pattern comprises the following steps: presetting a minimum value of the circle radius, and deleting an abnormal minimum enveloping circle with the circle radius smaller than the minimum value of the circle radius according to the comparison between the circle radius and the minimum value of the circle radius;
after the calibration characteristic pattern is obtained, the circle center of the minimum enveloping circle is the calibration characteristic point;
the process of acquiring the actual coordinates of the calibration feature points comprises the following steps: after the calibration characteristic pattern is obtained, the circle center of the minimum enveloping circle is the calibration characteristic point; carrying out coordinate sequencing on the calibration characteristic points, taking four error-free points far away from the origin on the XY coordinate axis as positioning points, and establishing a homography matrix according to the corresponding relation between the pixel coordinates and the galvanometer coordinates; after perspective transformation is carried out on the calibration characteristic points by adopting a homography matrix, pixel coordinates are converted into galvanometer coordinates to obtain actual coordinates of the calibration characteristic points;
after the calibration characteristic points are obtained, comparing the number of the calibration characteristic points with the filling circle array scale, and carrying out the next step after the number of the calibration characteristic points is equal to the filling circle array scale; the filled circle array scale is the circle array scale filled in the calibration characteristic pattern;
the calibration characteristic pattern is formed by combining simple primitives, and the pattern processing is not subjected to distortion correction and contains coordinate error information; according to the error estimation model, the coordinate point error of the uncorrected pattern on the axis is zero and can represent an ideal position, so that the coordinate difference between a point which is not on the axis and the projection point on the two coordinate axes is the error of the point in the two directions of the X axis and the Y axis, namely the X component and the Y component of the figure distortion; therefore, the characteristic point coordinates are obtained through visual identification detection and calculation, and errors or correction parameters of each characteristic point required by a correction compensation control algorithm can be calculated to construct a correction error table.
6. An electronic device comprising a memory and a processor and computer instructions stored on the memory and executed on the processor, the computer instructions when executed by the processor performing the method of any of claims 1-4.
7. A computer-readable storage medium storing computer instructions which, when executed by a processor, perform the method of any one of claims 1 to 4.
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| CN116991114B (en) * | 2023-09-26 | 2023-12-19 | 西安交通大学 | Method for measuring and compensating and correcting splicing errors in laser processing |
| CN117620488B (en) * | 2024-01-26 | 2024-03-29 | 深圳市智鼎自动化技术有限公司 | Modularized multi-axis laser galvanometer motion controller |
| CN118229801B (en) * | 2024-05-23 | 2024-07-16 | 吉林长华汽车部件有限公司 | Method and device for calibrating positions of camera and vibrating mirror, and aiming at hit and processed targets |
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