Multi-galvanometer cooperative laser processing splicing calibration method

Abstract

The invention discloses a multi-galvanometer cooperative laser processing splicing calibration method, and relates to the technical field of additive manufacturing, and the method comprises the steps: dividing a to-be-processed image into a plurality of sub-unit images through an image segmentation processing technology, then completing the splicing processing, and carrying out the calibration through a nominal parameter calibration matrix of each galvanometer, the overall processing breadth requirement can be met, meanwhile, the optimal processing area of each galvanometer and overall rotation and translation calibration of a single galvanometer are considered, and then a global error threshold value obtained through conversion of a processing result of an evaluation breadth based on a virtual large field lens method is used for processing quality evaluation so as to adjust a splicing calibration method. According to the technical scheme, a plurality of galvanometers can use a calibration strategy of a single equivalent large field lens, and then the splicing problem and the calibration correction problem between the adjacent galvanometers are considered one by one, so that the dependence of the splicing precision of the whole system on single calibration is reduced, the calibration error in the whole processing breadth can be eliminated, and the processing effect is improved.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a multi-galvanometer collaborative laser processing splicing calibration method. Background Art

[0002] 3D printing is the common name for Additive Manufacturing (AM). AM technology integrates computer-aided design, material processing and forming technology, and is based on digital model files. Through software and CNC systems, special metal materials, non-metallic materials and medical biomaterials are stacked layer by layer in the manner of extrusion, sintering, melting, photocuring, and spraying to produce physical objects.

[0003] Galvanometer laser processing is a commonly used additive manufacturing technology. With the pursuit of larger size and higher printing efficiency, the application of multi-galvanometer partition scanning and collaborative processing is becoming more and more common. It can be used to produce larger workpieces and has high practical significance.

[0004] However, in the multi-galvanometer stitching system, the synchronous control of multiple galvanometers and the precision processing of overlapping areas have become key factors restricting the efficiency of the multi-galvanometer stitching system. These problems not only involve complex adjustment and testing processes, but may also lead to deviations in laser processing results. When multiple galvanometers work at the same time, any position offset, such as non-levelness or deviation from the center point, will affect the final laser processing quality. The traditional single-unit independent calibration method is not only time-consuming and labor-intensive, but also lacks global considerations. Especially when there are a large number of galvanometers, manual adjustment is not only inefficient, but also difficult to ensure the accuracy of calibration and the consistency of errors, resulting in limited stitching accuracy and performance of the entire multi-galvanometer stitching system. Summary of the invention

[0005] In response to the above problems and technical requirements, this application proposes a multi-galvanometer collaborative laser processing splicing calibration method. The technical solution of this application is as follows: A multi-galvanometer collaborative laser processing splicing calibration method, the multi-galvanometer collaborative laser processing splicing calibration method comprising: Divide the image to be processed into a plurality of sub-unit images according to the scanning range of each galvanometer in the multi-galvanometer stitching system, each sub-unit image corresponds to a galvanometer in the multi-galvanometer stitching system and each sub-unit image does not exceed the scanning range of the corresponding galvanometer; Extract edge pixels of each sub-unit image respectively, and perform interpolation fitting on the edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process; Using the nominal parameter calibration matrix of each galvanometer, calibrate the stitched sub-unit image corresponding to the galvanometer to obtain a calibrated sub-unit image; Control each galvanometer to process according to the corresponding calibrated sub-unit image, and when it is determined that the calibration errors of each calibrated sub-unit image are evaluated as qualified, use the global error threshold to evaluate the processing quality of the image to be processed; When the processing quality of the image to be processed is evaluated as unqualified using the global error threshold, the interpolation fitting method is adjusted and the step of interpolating and fitting the edge pixels of two adjacent sub-unit images is re-executed to correct the two sub-unit images to complete the stitching process, until the processing quality of the image to be processed is evaluated as qualified using the global error threshold and the stitching calibration of the multi-galvanometer stitching system is completed; wherein the global error threshold is obtained by converting the processing results of the evaluation format based on the virtual large-field mirror method using the multi-galvanometer stitching system.

[0006] Its further technical solution is that the multi-galvanometer collaborative laser processing splicing calibration method also includes: The rectangular evaluation format is copied into a multi-stitched evaluation format in a k*k multi-stitched form, and it is determined that the focal length of the virtual large field lens corresponding to the multi-stitched evaluation format is k*k times the focal length of the field lens corresponding to the original evaluation format, and the data representation accuracy of the multi-stitched evaluation format is k times the data representation accuracy of the original evaluation format; wherein the multi-galvanometer stitching system includes a plurality of galvanometers arranged in k*k, the evaluation format does not exceed the scanning range of a single galvanometer, and the integer parameter k≥2; Using the nominal parameter calibration matrix of each galvanometer, the evaluation width corresponding to the galvanometer is calibrated to obtain the calibrated evaluation width, and each galvanometer in the multi-galvanometer splicing system is controlled to process according to the corresponding calibrated evaluation width; The global error threshold is obtained by converting the processing results of the multi-galvanometer stitching system on the multi-stitching evaluation formats.

[0007] A further technical solution is to convert the processing results of the multi-galvanometer stitching system on the multi-stitching evaluation format to obtain a global error threshold including: The processing result of the multi-jointed evaluation format and the maximum processing error of the multi-jointed evaluation format are reduced by k*k as the global error threshold.

[0008] A further technical solution is to control each galvanometer to process according to the corresponding calibrated sub-unit image, including: Dividing all the galvanometers into a plurality of galvanometer splicing groups in sequence according to the processing order of the sub-unit images corresponding to the respective galvanometers, each galvanometer splicing group including a plurality of galvanometers; The command data of the corresponding galvanometer is generated according to the pixel line processing trajectory of the calibrated sub-unit image of each sub-unit image, the command data of multiple galvanometers in the same galvanometer splicing group are encapsulated in the same galvanometer splicing group control instruction, and the galvanometer splicing group control instruction is sent to the multi-galvanometer splicing system for controlling the multiple galvanometers in the same galvanometer splicing group. The number of galvanometers in the same galvanometer splicing group is determined based on the constraint that the update cycle of the galvanometer splicing group control instruction is less than the galvanometer instruction update cycle requirement.

[0009] Its further technical solution is that each galvanometer includes an x-axis and a y-axis, the instruction data of each galvanometer includes x-axis instruction data and y-axis instruction data, each galvanometer splicing group constructed includes two galvanometers, and the obtained galvanometer splicing group control instruction includes a start bit, the x-axis instruction data of the first galvanometer in the galvanometer splicing group, the y-axis instruction data of the first galvanometer in the galvanometer splicing group, the x-axis instruction data of the second galvanometer in the galvanometer splicing group, the y-axis instruction data of the second galvanometer in the galvanometer splicing group and a parity check bit, totaling 82 bits, the update frequency of each bit is 1 / 12.4MHZ, and the update period of the galvanometer splicing group control instruction is 6.61μs.

[0010] A further technical solution is to perform interpolation fitting on edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process, including: The edge pixels of two adjacent sub-unit images are interpolated using a bilinear interpolation algorithm to obtain an edge pixel interpolation result, and the interpolated edge pixel interpolation result is merged into one of the sub-unit images to correct the two sub-unit images.

[0011] A further technical solution is that dividing the image to be processed into a plurality of sub-unit images includes: Divide the rectangular area where the image to be processed is located into grids, the size of each grid is the same and the range of each grid does not exceed the scanning range of the corresponding galvanometer; The image to be processed in each grid is taken as a candidate sub-image, and the candidate sub-image is corrected based on the image features of the image to be processed to obtain a sub-unit image.

[0012] A further technical solution is that the candidate sub-image is corrected based on the image features of the image to be processed to obtain the sub-unit image, which includes: The K-Means clustering algorithm is used to cluster pixels of the image to be processed to obtain several cluster sub-images; For any candidate sub-image, when there is a cluster sub-image completely located within the range of the candidate sub-image, the cluster sub-image is used as the sub-unit image; otherwise, the candidate sub-image is directly used as the sub-unit image.

[0013] A further technical solution is that the multi-galvanometer collaborative laser processing splicing calibration method also includes: When the processing error between the processing result of any calibrated sub-unit image and the calibrated sub-unit image reaches the sub-unit error threshold, adjust or replace the galvanometer corresponding to the calibrated sub-unit image; until the processing errors between the processing results of all calibrated sub-unit images and the corresponding calibrated sub-unit images are less than the sub-unit error threshold, it is determined that the calibration errors of all calibrated sub-unit images are evaluated as qualified. A further technical solution is to use the global error threshold to evaluate the processing quality of the image to be processed, including: When the processing result of the image to be processed and the maximum processing error of the image to be processed are less than the global error threshold, it is determined that the processing quality of the image to be processed is qualified; otherwise, it is determined that the processing quality of the image to be processed is unqualified.

[0014] The beneficial technical effects of this application are: The present application discloses a method for calibration of splicing of multiple galvanometers in collaborative laser processing. The method constrains and sets the effective and optimal working area of ​​a single galvanometer through preliminary image segmentation processing. The method then performs splicing calibration to meet the overall processing width requirement while taking into account the optimal processing area of ​​each galvanometer and the overall rotation and translation calibration of a single galvanometer. The overall calibration data is then split into local single or grouped galvanometer calibration compensation data. The method enables multiple galvanometers to be calibrated using a single equivalent large-field mirror, and then considers the splicing problem and calibration correction problem between adjacent galvanometers one by one, thereby reducing the dependence of the overall system splicing accuracy on a single calibration. The mapping relationship between matrix operations and multi-head splicing is utilized to eliminate calibration errors within the entire processing width and improve the processing effect. The "overall-partition-overall" calibration and evaluation scheme is beneficial to ensuring the consistency of the processing trajectory effects of various parts during the processing of large-size parts.

[0015] This method regards the image to be processed as a two-dimensional digital matrix, performs graphic processing, introduces coefficient matrices of the same order for each unit, and discretizes the area to be processed to include mathematical modeling of actual differences in individual rotation, translation, scaling, etc. of each unit. The discretization method follows the general law of field lens optical angle and format distortion, maps the processed graphic pixel coordinate matrix to each single galvanometer, realizes overall splicing, independent calculation of local areas of a single unit, and smoothly transitions to the overall splicing format. Without changing physical parameters such as the position of the galvanometer, the deviation of the final laser processing result can be minimized, achieving the same printing effect as when the galvanometer is at the center point.

[0016] The method designs appropriate control instruction groups for different numbers of galvanometers. The galvanometer control instruction format is designed to ensure that the synchronous control of each galvanometer and the real-time requirements of the 10us control cycle are met. At the same time, the grouping of the control instruction transmission signal of the multi-galvanometer splicing system and the determination of the default rules of the splicing sequence are taken into account to improve the processing efficiency and control accuracy of the multi-galvanometer splicing system, while reducing the demand for the number of galvanometer control cards in the multi-galvanometer splicing system, reducing the system cost and increasing the design flexibility of the control system. The laser galvanometer control card can generate large-format continuous single galvanometer instructions, which is beneficial to improving the processing efficiency in conjunction with the data cutting and splicing processing algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a method flow chart of a multi-galvanometer collaborative laser processing splicing calibration method according to an embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of an image to be processed and grid division of the rectangular area where the image is located in an example of the present application.

[0019] Figure 3 It is the instruction format of the galvanometer splicing group control instruction in one embodiment of the present application. DETAILED DESCRIPTION

[0020] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0021] This application discloses a multi-galvanometer collaborative laser processing splicing calibration method, please refer to Figure 1 As shown in the flowchart, the multi-galvanometer collaborative laser processing splicing calibration method includes: Step 1: Divide the image to be processed into a plurality of sub-unit images according to the scanning range of each galvanometer in the multi-galvanometer stitching system.

[0022] A mapping relationship is established between the multiple sub-unit images obtained by division and the multiple galvanometers in the multi-galvanometer splicing system, each sub-unit image corresponds to a galvanometer in the multi-galvanometer splicing system and each sub-unit image does not exceed the scanning range of the corresponding galvanometer, ensuring that the galvanometer can at least cover and scan the corresponding sub-unit image, but the number of sub-unit images obtained by division is not necessarily the same as the number of galvanometers in the multi-galvanometer splicing system. The method of obtaining multiple sub-unit images by division includes: (1) First, the rectangular area where the image to be processed is located is divided into grids. The size of each grid is the same and the range of each grid does not exceed the scanning range of the corresponding galvanometer. The actual image to be processed may be a regular shape or an irregular shape. Therefore, the image to be processed is first padded with 0 pixels to form a regular rectangular area, such as Figure 2 In the schematic diagram, the image to be processed is as follows Figure 2(a) in the figure shows an irregular shape. The rectangular area where the image to be processed is located by filling it with 0 pixels is as follows: Figure 2 As shown by the dotted line in (b), the rectangular area where the image to be processed is located is then grid-divided to obtain 12 grids.

[0023] All pixels in each grid obtained by division are valid pixels of the image to be processed, or only some pixels in each grid are valid pixels of the image to be processed, or all pixels in each grid are not valid pixels of the image to be processed. Figure 2 In the example (b), all pixels in the divided grids a2, a5, a6, a9, a10 and a11 are valid pixels of the image to be processed, only some pixels in the divided grids a1, a7, a8 and a12 are valid pixels of the image to be processed, and the divided grids a3 and a4 do not contain valid pixels of the image to be processed.

[0024] (2) The image to be processed in each grid is taken as a candidate sub-image, and the candidate sub-image is modified based on the image features of the image to be processed to obtain a sub-unit image.

[0025] As mentioned above, each grid is obtained by dividing the regular rectangular area where the image to be processed is located. In addition to the image to be processed, the regular rectangular area also includes 0 pixels padded. Therefore, only the image to be processed in each grid is extracted, and the area without the image to be processed does not need to be scanned. For example Figure 2 In the example of (b), the grids a3 and a4 do not contain candidate sub-images, the areas where the valid pixels of the image to be processed are located in the grids a1, a7, a8 and a12 are used as candidate sub-images, and the remaining white areas do not need to be scanned.

[0026] The candidate sub-image thus extracted can be directly used as the sub-unit image for subsequent processing. However, in order to further reduce the amount of data processing, a step of correcting the candidate sub-image based on the image features of the image to be processed is added, including: using the K-Means clustering algorithm to cluster the pixels of the image to be processed to obtain a number of clustered sub-images. Then, for any candidate sub-image, when there is a clustered sub-image that is completely within the range of the candidate sub-image, the clustered sub-image replaces the candidate sub-image as the sub-unit image, otherwise the candidate sub-image is directly used as the sub-unit image. Multiple clustered sub-images with similar features can be formed by clustering similar pixels. Replacing the candidate sub-image with them can reduce the amount of data and improve the efficiency of subsequent data processing on the basis of obtaining the graphic data that is as close to the original graphic as possible to ensure the quality of the graphic.

[0027] Step 2: extract edge pixels of each sub-unit image respectively, and perform interpolation fitting on the edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process.

[0028] In this step, the Canny edge detection method can be used to obtain the pixel gradient amplitude and direction. The gradient amplitude and direction reflect the change of the sub-unit image, thereby obtaining the edge pixels of the sub-unit image.

[0029] Then, the edge pixels of the sub-unit images are used for splicing processing, including using a bilinear interpolation algorithm to interpolate the edge pixels of two adjacent sub-unit images to obtain an edge pixel interpolation result, and merging the interpolated edge pixel interpolation result into one of the sub-unit images to correct the two sub-unit images.

[0030] Step 3: Use the nominal parameter calibration matrix of each galvanometer to calibrate the spliced ​​sub-unit image corresponding to the galvanometer to obtain a calibrated sub-unit image.

[0031] The nominal parameter calibration matrix of each galvanometer is used to characterize the distortion caused by the nominal parameters of the galvanometer itself. The nominal parameter calibration matrix can be calibrated in advance, including: pre-controlling each galvanometer to process the target pattern point, and comparing the processing result of the galvanometer on the target pattern point with the target pattern point, and fitting the transformation matrix between the two by the least squares method as the nominal parameter calibration matrix of the galvanometer. The nominal parameter calibration matrix of each galvanometer is obtained by combining the rotation matrix and the offset matrix, and because the nominal parameters of different galvanometers are different, the nominal parameter calibration matrix of each galvanometer is often different, and can be calibrated in advance.

[0032] The calibrated sub-unit image obtained by calibrating the nominal parameter calibration matrix of the galvanometer can realize the overall rotation and translation calibration function of a single galvanometer without changing the physical parameters such as the position of the galvanometer.

[0033] Step 4, controlling each galvanometer to process according to its corresponding calibrated sub-unit image.

[0034] First, the instruction data of the corresponding galvanometer is generated according to the pixel line processing trajectory of the calibrated sub-unit image of each sub-unit image. When generating the instruction data specifically, the matching relationship between the laser power and the speed of each processing axis of the galvanometer needs to be considered, including the matching of the spatial trajectory and the laser control timing to achieve time-space synchronous control. In addition, in order to ensure that the overall processing pattern will not be discontinuous, starting constraints and corner compensation will be added in the middle of the instruction. This application does not go into details about this part.

[0035] In order to reduce the demand for the number of galvanometer control cards in the multi-galvanometer splicing system and increase the design flexibility of the control system, this step divides all the galvanometers into multiple galvanometer splicing groups in sequence according to the processing order of the sub-unit images corresponding to each galvanometer, and each galvanometer splicing group includes multiple galvanometers, and then generates command data for the corresponding galvanometer according to the calibrated sub-unit image of each sub-unit image, encapsulates the command data of multiple galvanometers in the same galvanometer splicing group in the same galvanometer splicing group control instruction, and sends the galvanometer splicing group control instruction to the multi-galvanometer splicing system for controlling multiple galvanometers in the same galvanometer splicing group. The number of galvanometers in the same galvanometer splicing group is determined based on the constraint that the update cycle of the galvanometer splicing group control instruction is less than the galvanometer instruction update cycle requirement, that is, it is still guaranteed to meet the synchronous control of each galvanometer and the real-time requirements of the 10us control cycle.

[0036] In one embodiment, each galvanometer includes an x-axis and a y-axis, and the command data generated for each galvanometer includes x-axis command data and y-axis command data, and each galvanometer splicing group constructed thereby includes two galvanometers, and the obtained galvanometer splicing group control command includes a start bit, an x-axis command data of the first galvanometer in the galvanometer splicing group, a y-axis command data of the first galvanometer in the galvanometer splicing group, an x-axis command data of the second galvanometer in the galvanometer splicing group, a y-axis command data of the second galvanometer in the galvanometer splicing group, and a parity check bit, such as Figure 3 The first galvanometer and the second galvanometer refer to two galvanometers in a galvanometer splicing group, and do not specifically refer to a certain galvanometer.

[0037] Among them, the start bit and the parity check bit each occupy one bit, and the instruction data of each processing axis of each galvanometer in each galvanometer splicing group occupies 20 bits. Therefore, the control instruction of the entire galvanometer splicing group occupies a total of 82 bits. The update frequency of each bit is 1 / 12.4MHZ, and the update cycle of the control instruction of the entire galvanometer splicing group is 6.61μs, which meets the 10μs instruction update cycle requirement of conventional galvanometers.

[0038] When the multi-galvanometer splicing system contains different numbers of galvanometers, multiple galvanometer splicing groups can be built with two galvanometers as one galvanometer splicing group. The above-mentioned galvanometer control instruction format design ensures that the synchronous control of each galvanometer and the real-time requirements of the 10us control cycle are met, while taking into account the grouping of the control instruction transmission signal of the multi-galvanometer splicing system and the determination of the default rules for the splicing sequence, so as to improve the processing efficiency and control accuracy of the multi-galvanometer splicing system, reduce the demand for the number of galvanometer control cards of the multi-galvanometer splicing system, reduce system costs and increase the design flexibility of the control system.

[0039] Step 5, first evaluate the calibration errors of each calibrated sub-unit image separately, including: comparing the processing results of each calibrated sub-unit image with the calibrated sub-unit image through an image detection and processing tool to obtain a processing error, and when the processing error between the processing result of any calibrated sub-unit image and the calibrated sub-unit image reaches a sub-unit error threshold, adjusting or replacing the galvanometer corresponding to the calibrated sub-unit image, and then re-controlling each galvanometer to process according to the corresponding calibrated sub-unit image, so as to solve the defects of the galvanometer itself or solve the deviation caused by non-level installation or skewed non-centering. Until the processing errors of the processing results of all calibrated sub-unit images and the corresponding calibrated sub-unit images are less than the sub-unit error threshold, it is determined that the calibration errors of each calibrated sub-unit image are evaluated as qualified.

[0040] Step 6, when it is determined that the calibration errors of the sub-unit images after calibration are evaluated as qualified, further use the global error threshold to evaluate the processing quality of the image to be processed, including: comparing the processing result of the image to be processed with the image to be processed by an image detection and processing tool to obtain the maximum processing error; when the maximum processing error is less than the global error threshold, it is determined that the processing quality of the image to be processed is qualified; otherwise, it is determined that the processing quality of the image to be processed is unqualified.

[0041] When the processing quality of the image to be processed is unqualified, return to step 2 to adjust the interpolation fitting method and re-execute the interpolation fitting of the edge pixels of the two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process. When adjusting the interpolation fitting method, the weight distribution in the bilinear interpolation algorithm can be adjusted to adjust the splicing effect. When the processing quality of the image to be processed is qualified, the splicing calibration of the multi-galvanometer splicing system is completed, and the multi-galvanometer splicing system can be used for collaborative processing according to the above-mentioned splicing method.

[0042] The global error threshold used in this step for processing quality assessment is obtained by pre-converting the processing results of the assessment format using a multi-galvanometer splicing system based on a virtual large-field mirror method. The method for obtaining the global error threshold includes: (1) The rectangular evaluation format is copied into a multi-stitching evaluation format in the form of k*k multi-stitching, where the integer parameter k ≥ 2 and is based on the number of galvanometers in the multi-galvanometer stitching system. The multi-galvanometer stitching system contains multiple galvanometers arranged in k*k. The evaluation format is an arbitrarily selected format that does not exceed the scanning range of a single galvanometer.

[0043] The multi-stitched evaluation format can be regarded as a large evaluation format, and the focal length of the virtual large field lens corresponding to the multi-stitched evaluation format is k*k times the focal length of the field lens corresponding to the original evaluation format. At the same time, the data representation accuracy of the multi-stitched evaluation format is k times the data representation accuracy of the original evaluation format. For example, if the data representation accuracy of the original evaluation format is 16-bit, the data representation accuracy of the 2*2 multi-stitched evaluation format becomes 17-bit, which is a 2-fold increase. The spliced ​​multi-stitched evaluation format can be replaced by a virtual large field lens and a virtual large galvanometer model to construct a virtual large field lens evaluation model.

[0044] (2) Using the nominal parameter calibration matrix of each galvanometer, the evaluation format corresponding to the galvanometer is calibrated to obtain the calibrated evaluation format, and each galvanometer in the multi-galvanometer splicing system is controlled to process according to its corresponding calibrated evaluation format. This part is similar to the above-mentioned method of calibrating and processing the sub-unit image, and will not be repeated here.

[0045] (3) Then, the global error threshold is obtained based on the processing results of the multi-stitching evaluation format converted by the multi-galvanometer stitching system. This includes: using an image detection and processing tool to compare the processing results of the multi-stitching evaluation format with the multi-stitching evaluation format, obtaining the data error between the two as the maximum processing error, and then reducing the maximum processing error by k*k as the global error threshold. This method can magnify the nominal parameters of a single field lens to a certain multiple, and indirectly associate it with the actual single-unit galvanometer and field lens nominal parameter characteristics at the same time through the "virtual large field lens" method of "magnifying first and then reducing".

[0046] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A multi-galvanometer collaborative laser processing splicing calibration method, characterized in that: The multi-galvanometer collaborative laser processing splicing calibration method comprises: Divide the image to be processed into a plurality of sub-unit images according to the scanning range of each galvanometer in the multi-galvanometer stitching system, each sub-unit image corresponds to a galvanometer in the multi-galvanometer stitching system and each sub-unit image does not exceed the scanning range of the corresponding galvanometer; Extract edge pixels of each sub-unit image respectively, and perform interpolation fitting on the edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process; Using the nominal parameter calibration matrix of each galvanometer, calibrate the stitched sub-unit image corresponding to the galvanometer to obtain a calibrated sub-unit image; Control each galvanometer to process according to the corresponding calibrated sub-unit image, and when it is determined that the calibration errors of each calibrated sub-unit image are evaluated as qualified, use the global error threshold to evaluate the processing quality of the image to be processed; When the processing quality of the image to be processed is evaluated as unqualified using the global error threshold, the interpolation fitting method is adjusted and the step of performing interpolation fitting on the edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the stitching process is re-executed until the processing quality of the image to be processed is evaluated as qualified using the global error threshold and the stitching calibration of the multi-galvanometer stitching system is completed; wherein the global error threshold is obtained by converting the processing results of the evaluation format using the multi-galvanometer stitching system based on the virtual large-field mirror method.

2. The multi-galvanometer collaborative laser processing splicing calibration method according to claim 1 is characterized in that: The multi-galvanometer collaborative laser processing splicing calibration method also includes: The rectangular evaluation format is copied into a multi-stitched evaluation format in a k*k multi-stitched form, and it is determined that the focal length of the virtual large field lens corresponding to the multi-stitched evaluation format is k*k times the focal length of the field lens corresponding to the original evaluation format, and the data representation accuracy of the multi-stitched evaluation format is k times the data representation accuracy of the original evaluation format; wherein the multi-galvanometer stitching system includes a plurality of galvanometers arranged in k*k, the evaluation format does not exceed the scanning range of a single galvanometer, and the integer parameter k≥2; Using the nominal parameter calibration matrix of each galvanometer, the evaluation format corresponding to the galvanometer is calibrated to obtain a calibrated evaluation format, and each galvanometer in the multi-galvanometer splicing system is controlled to perform processing according to the corresponding calibrated evaluation format; The global error threshold is obtained by converting the processing result of the multi-galvanometer stitching system on the multiple stitching evaluation formats.

3. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 2 is characterized in that: The global error threshold is obtained by converting the processing result of the multi-galvanometer stitching system on the multi-stitching evaluation format, including: The processing result of the multiple splicing evaluation frames and the maximum processing error of the multiple splicing evaluation frames are reduced by k*k as the global error threshold.

4. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 1 is characterized in that: Controlling each galvanometer to process according to its corresponding calibrated sub-unit image includes: Dividing all the galvanometers into a plurality of galvanometer splicing groups in sequence according to the processing order of the sub-unit images corresponding to the respective galvanometers, each galvanometer splicing group including a plurality of galvanometers; The command data of the corresponding galvanometer is generated according to the pixel line processing trajectory of the calibrated sub-unit image of each sub-unit image, the command data of multiple galvanometers in the same galvanometer splicing group are encapsulated in the same galvanometer splicing group control instruction, and the galvanometer splicing group control instruction is sent to the multi-galvanometer splicing system for controlling the multiple galvanometers in the same galvanometer splicing group. The number of galvanometers in the same galvanometer splicing group is determined based on the constraint that the update cycle of the galvanometer splicing group control instruction is less than the galvanometer instruction update cycle requirement.

5. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 4 is characterized in that: Each galvanometer includes an x-axis and a y-axis, and the instruction data of each galvanometer includes x-axis instruction data and y-axis instruction data. Each constructed galvanometer splicing group includes two galvanometers, and the obtained galvanometer splicing group control instruction includes a start bit, the x-axis instruction data of the first galvanometer in the galvanometer splicing group, the y-axis instruction data of the first galvanometer in the galvanometer splicing group, the x-axis instruction data of the second galvanometer in the galvanometer splicing group, the y-axis instruction data of the second galvanometer in the galvanometer splicing group, and a parity check bit, a total of 82 bits, the update frequency of each bit is 1 / 12.4MHZ, and the update period of the galvanometer splicing group control instruction is 6.61μs.

6. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 1 is characterized in that: Interpolating and fitting the edge pixels of two adjacent sub-unit images to correct the two sub-unit images to complete the splicing process includes: The edge pixels of two adjacent sub-unit images are interpolated using a bilinear interpolation algorithm to obtain an edge pixel interpolation result, and the interpolated edge pixel interpolation result is merged into one of the sub-unit images to correct the two sub-unit images.

7. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 1 is characterized in that: Dividing the image to be processed into multiple sub-unit images includes: Divide the rectangular area where the image to be processed is located into grids, wherein the sizes of the grids are the same and the range of each grid does not exceed the scanning range of the corresponding galvanometer; The image to be processed in each grid is taken as a candidate sub-image, and the candidate sub-image is corrected based on the image features of the image to be processed to obtain a sub-unit image.

8. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 7 is characterized in that: Correcting the candidate sub-image based on the image feature of the image to be processed to obtain the sub-unit image includes: Using K-Means clustering algorithm to cluster pixels of the image to be processed to obtain a number of cluster sub-images; For any candidate sub-image, when there is a cluster sub-image completely located within the range of the candidate sub-image, the cluster sub-image is used as the sub-unit image; otherwise, the candidate sub-image is directly used as the sub-unit image.

9. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 1, characterized in that: The multi-galvanometer collaborative laser processing splicing calibration method also includes: When the processing error between the processing result of any calibrated sub-unit image and the processing error of the calibrated sub-unit image reaches the sub-unit error threshold, adjust or replace the galvanometer corresponding to the calibrated sub-unit image; until the processing errors between the processing results of all calibrated sub-unit images and the corresponding calibrated sub-unit images are less than the sub-unit error threshold, it is determined that the calibration errors of all calibrated sub-unit images are evaluated as qualified.

10. The multi-galvanometer coordinated laser processing splicing calibration method according to claim 1, characterized in that: Using the global error threshold to evaluate the processing quality of the image to be processed includes: When the processing result of the image to be processed and the maximum processing error of the image to be processed are less than the global error threshold, it is determined that the processing quality of the image to be processed is qualified; otherwise, it is determined that the processing quality of the image to be processed is unqualified.

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