Laser galvanometer detection system with temperature drift self-detection and correction functions and working method

Abstract

The invention relates to a laser galvanometer detection system with temperature drift self-detection and correction functions. The laser galvanometer detection system comprises an error judgment module and an error calibration module, the error judgment module comprises a CMOS image sensing module, a visual detection module and a storage module; the error calibration module comprises a calibration module and a laser marking module; the CMOS image sensing module is used for shooting a high-definition image, and the visual detection module can generate a prediction image and perform deviation identification on the image shot by the CMOS image sensing module. According to the invention, the temperature drift error is automatically detected through real-time detection of the position drift error of each visual single detection area in the galvanometer processing breadth, and each visual single detectable area is detected one by one to form an adjacent array, so that the temperature drift error detection of the whole processing breadth is realized; and comparing the difference between'theoretical due 'and'actual existing' through an intelligent algorithm so as to detect, compensate and correct the error in real time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of detection and correction of a laser galvanometer, and in particular to a laser galvanometer detection system with temperature drift self-detection and correction and a working method. BACKGROUND

[0002] The laser galvanometer is increasingly widely applied in various industries, and users have higher and higher requirements for the position control accuracy and stability of the laser galvanometer, especially in long-time continuous working application scenarios. The temperature-related drift index becomes a technical difficulty in the high-end laser galvanometer industry. During long-period continuous operation of the laser galvanometer, the mechanical structure deformation in the laser galvanometer, the position detection sensor of the laser galvanometer motor, and the electronic components used in the laser galvanometer motor driver are all affected by the change of the operation environment temperature, so that the laser galvanometer mark position produces gain drift or zero drift, and finally the overall mark accuracy is affected. The current conventional response method is that the user periodically measures the machining trajectory accuracy and offset to judge the temperature drift data and manually corrects the deviation, or some cost-insensitive applications select to replace the traditional galvanometer with an expensive full-digital laser galvanometer with a high-resolution grating to improve the temperature drift performance index. However, there is little specific countermeasure for the temperature drift self-detection and correction of the laser galvanometer.

[0003] The prior art mainly uses the method of manually correcting the temperature drift of the laser galvanometer by periodically measuring, which can solve part of the non-continuous machining of the laser equipment application, but cannot meet the actual needs for the application occasions requiring long-time continuous working of the laser galvanometer. Some laser equipment uses a vision sensor to detect the laser galvanometer machining position and trajectory compared with the target value in real time, which can judge the temperature drift anomaly, but cannot correct the influence of the laser galvanometer temperature drift in real time, and can only alarm and stop when the anomaly occurs, thereby reducing the machining continuity and machining efficiency.

[0004] Therefore, the application provides a laser galvanometer detection system with temperature drift self-detection and correction and a working method.

[0005] CONTENT

[0006] In view of the above-mentioned shortcomings in the prior art, the application provides a laser galvanometer detection system with temperature drift self-detection and correction and a working method, and a closed-loop detection system is constructed. Instead of passively waiting for the error accumulation to be visible to the naked eye or causing machining alarm or defect, the system actively detects and compensates for the error in each machining process by comparing the difference between the “theoretically should have” and the “actually have” through an intelligent algorithm.

[0007] The technical scheme adopted by the application is as follows:

[0008] A laser galvanometer detection system with temperature drift self-detection and correction comprises:

[0009] error judging module;

[0010] error calibration module;

[0011] The error judging module comprises a CMOS image sensing module, a visual detection module and a storage module, and the error calibration module comprises a calibration module and a laser marking module.

[0012] The CMOS image sensing module is used for shooting high-definition images, and the visual detection module is capable of generating a prediction image and identifying deviations of images shot by the CMOS image sensing module.

[0013] Further features are as follows:

[0014] The visual detection module is internally provided with a coordinate transformation algorithm.

[0015] The laser marking module comprises a galvanometer and a laser.

[0016] The application further discloses a working method of a laser galvanometer detection system with temperature drift self-checking and correction, comprising the following steps:

[0017] The marking surface is defined as N regions, denoted as No. 1, No. 2, …, and No. N positions, a CMOS image sensing module is driven to move to the N regions in sequence, and the CMOS image sensing module shoots a clear high-definition image at each position and stores the image into a storage module, denoted as P1, P2, …, and PN;

[0018] During marking at the No. 1 position, the laser marking module records all position instructions POS1 and stores the instructions into the storage module;

[0019] A visual detection module reads the image P1 and all position instructions POS1, a coordinate transformation algorithm of the visual detection module establishes a mapping model from a “galvanometer instruction coordinate system” to a “CMOS image pixel coordinate system”, the coordinate transformation algorithm traverses each position instruction in POS1, calculates a pixel position in the reference image P1 where a theoretical laser point should appear by using the mapping model, and marks all calculated pixel points on the image P1, and stores the marked P1 image into the storage module, denoted as K1.

[0020] The laser marking module receives the position instructions POS1, drives the galvanometer and the laser to process a workpiece, after marking is completed, the CMOS image sensing module is accurately positioned back to the No. 1 position, shoots an image of the No. 1 position after actual processing, and stores the image into the storage module, denoted as M1.

[0021] The visual detection module reads the images M1 and K1 from the storage module. The coordinate transformation algorithm of the visual detection module first identifies the features in common in the images M1 and K1 that are not affected by the machining, and adjusts the two images to be completely aligned in the same coordinate system by calculating the translation, rotation and other transformation relationships between the features. Then, the coordinate transformation algorithm performs a pixel-by-pixel subtraction operation on the images K1 and M1. The non-zero difference areas are identified as abnormalities. The coordinate transformation algorithm accurately locates the shape, size and center coordinates of the difference areas through clustering, edge detection and other image processing techniques.

[0022] The visual detection module outputs a set of quantized error vector data.

[0023] The calibration module reads the quantized error vector data output by the visual detection module, and compensates the position instructions sent to the galvanometer in real time.

[0024] Each feature point in the images P1, P2, …, PN corresponds to an accurate, known theoretical coordinate in the galvanometer coordinate system.

[0025] Each feature point in the images P1, P2, …, PN includes a mark on the workpiece, the edge of a fixture, or a pre-made standard target.

[0026] The calibration module reversely deduces the internal cause of the error, which is the current temperature offset of the X / Y motor. The X / Y coordinates of all subsequent instructions are subtracted by a compensation value in advance, thereby "tricking" the galvanometer to make its deviated movement eventually produce a non-deviated trajectory.

[0027] The calibration module converts the deviation pixels into instruction deviations, and generates a corresponding table through the installation and debugging process.

[0028] The calibration module generates a position instruction calibration table by adding a deviation value to the original instruction.

[0029] In subsequent laser marking, the instruction calibration table is added to the original instruction to generate a new instruction, which is sent to the laser marking module; and the laser marking module performs marking.

[0030] The application has the following beneficial effects:

[0031] The application has a compact and reasonable structure, and is easy to operate. The temperature drift error of each visual single detection area is detected in real time to automatically detect the temperature drift error. Each visual single detection area is detected to form an adjacent array to realize the temperature drift error detection of the entire machining area. The drift error is corrected by correcting the real-time position instruction of the laser galvanometer, so that the real-time laser galvanometer position trajectory detection value in each visual single detection area and the machining trajectory error are within an acceptable range, thereby realizing automatic correction of the temperature drift.

[0032] Meanwhile, the application also has the following advantages:

[0033] (1) With the low-cost CMOS image sensor module, the laser galvanometer temperature drift self-checking and correction function is realized under the premise of ensuring the compact structure of the galvanometer; combined with the internal optical path characteristics of the laser galvanometer, the overall processing range is divided into multiple continuous visual single detection areas, and the position drift error of each visual single detection area is detected respectively, the single calculation and judgment time is reduced, the real-time performance is improved, and it is especially suitable for large-scale continuous step-by-step regional processing application occasions, that is, the real-time performance of detection is ensured and the calculation amount is reduced.

[0034] (2) Through the visual detection module of the laser galvanometer, the comparison between the standard temperature drift reference position and the actual processing reference position is realized, which realizes the calculation and judgment of the temperature drift data and provides numerical basis for realizing the temperature drift correction of each segmented area, thereby ensuring the temperature drift detection and correction of the whole processing range.

[0035] (3) The laser equipment suitable for large-scale long-period continuous processing not only ensures the real-time online temperature drift detection and correction of the laser galvanometer, but also reduces the system cost and the complexity of system design for overcoming the problem of galvanometer temperature drift.

[0036] (4) The laser galvanometer with temperature drift self-checking and correction simplifies the temperature drift detection and correction method of the laser system trajectory processing precision, and is more flexible and convenient when integrated with the laser system, realizes the perfect closed loop from "perception" to "execution", and not only alarms when the error exceeds the tolerance, but also actively corrects the error online and in real time, so as to ensure that the equipment can maintain high processing precision for a long time in continuous work. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structure block diagram of the temperature drift self-checking and correction system of the application.

[0038] Figure 2 It is a working process schematic diagram of the laser galvanometer visual detection module of the application.

[0039] Figure 3 It is a working process schematic diagram of the calibration module of the application.

[0040] Figure 4 It is a laser galvanometer temperature drift correction process schematic diagram of the application.

[0041] Figure 5 It is a periodic real-time implementation process schematic diagram of the laser galvanometer temperature drift correction process of the application. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application are described below with reference to the accompanying drawings.

[0043] As shown in the drawings, a laser galvanometer detection system with temperature drift self-checking and correction includes an error judgment module and an error calibration module. The error judgment module includes a CMOS image sensing module, a visual detection module, and a storage module. The error calibration module includes a calibration module and a laser marking module. Figure 1

[0044] The CMOS image sensing module is a high-definition image sensor, which is used to take high-definition images and provide high-definition images for the visual detection module.

[0045] As shown in the drawings, the visual detection module can generate a predicted image according to an instruction input and identify the deviation of the image taken by the CMOS image sensing module. The instruction input is an instruction containing (x, y) coordinates sent by the upper computer. Figure 1

[0046] The visual detection module runs a coordinate transformation algorithm internally.

[0047] The storage module is used to store the input instruction and store the pictures taken by the visual detection module.

[0048] The calibration module can calibrate the output deviation of the visual detection module.

[0049] The laser marking module is used for marking.

[0050] The working process of the visual detection module is as follows:

[0051] Start the visual detection module.

[0052] Initialize the storage module and start the CMOS image sensing module.

[0053] Define the marking surface as N regions, denoted as No. 1, No. 2, …, and No. N positions. Drive the CMOS image sensing module to move to the N regions in sequence, and the CMOS image sensing module takes a clear high-definition image at each position and stores it in the storage module, denoted as P1, P2, …, and PN. The CMOS image sensing module takes a picture containing the edge of the marking object, which is used for self-calibration of the visual detection module.

[0054] During the marking process at No. 1 position, the laser marking module records all the position instructions POS1 and stores them in the storage module.

[0055] After the laser marking module completes the marking at No. 1 position, the CMOS image sensing module takes an image of No. 1 position and stores it in the storage module, denoted as M1.

[0056] ​​Visual detection module reads image P1 and all position instructions POS1, converts all position instructions in POS1 into pixel marks in P1 image through algorithm, stores the marked P1 image into storage module, recorded as K1;

[0057] Visual detection module compares pixel difference of marked position between image M1 and K1;

[0058] Visual detection module outputs deviation.

[0059] Calibration module working process:

[0060] Start calibration module;

[0061] Calibration module reads deviation output by visual detection module;

[0062] Calibration module converts deviation pixel into instruction deviation through corresponding table generated in installation and debugging process;

[0063] Calibration module generates position instruction calibration table by adding deviation value to original instruction;

[0064] In subsequent laser marking, add instruction calibration table to original instruction to generate new instruction, and send to laser marking module;

[0065] Laser marking module performs marking.

[0066] A working method of laser galvanometer detection system with temperature drift self-checking and correction, comprising the following steps:

[0067] Predefine the marking surface as N regions, recorded as No. 1, No. 2, …, No. N positions, drive the CMOS image sensing module to move to the N regions in turn, and the CMOS image sensing module takes a clear high-definition image at each position and stores it into the storage module, recorded as P1, P2, …, PN; this group of images represents the "map" of the entire marking surface of the device under ideal cold state. Each feature point in the image (such as marks on the workpiece, edges of the fixture, and pre-made standard targets) corresponds to an accurate and known theoretical coordinate in the galvanometer coordinate system.

[0068] Laser marking module records all position instructions POS1 during marking at No. 1 position, and stores them into the storage module;

[0069] The visual detection module reads the image P1 and all the position instructions POS1, and a coordinate transformation algorithm of the visual detection module establishes a mapping model from a "galvanometer instruction coordinate system" to a "CMOS image pixel coordinate system"; the coordinate transformation algorithm traverses each position instruction in POS1, calculates, by using the mapping model, a pixel position in the reference image P1 at which the theoretical laser point should appear, and marks all the calculated pixel points on the image P1, and stores the marked P1 image in a storage module, denoted as K1; the image K1 is a theoretical result that should be observed by the CMOS image sensing module at the No. 1 position after the marking operation is completed under an ideal state, and is a "predicted image" or a "theoretical image".

[0070] The laser marking module receives the position instructions POS1, drives the galvanometer and the laser to process the workpiece, and after the marking is completed, the CMOS image sensing module accurately positions back to the No. 1 position, takes an image of the No. 1 position after the actual processing, and stores the image in the storage module, denoted as M1.

[0071] The visual detection module reads the images M1 and K1 from the storage module, a coordinate transformation algorithm of the visual detection module identifies, by calculation, a translation, rotation, or the like between features in the images M1 and K1 that are not affected by the processing, adjusts the two images to be completely aligned in the same coordinate system, and then performs a pixel-by-pixel subtraction operation on the images K1 and M1, and identifies abnormal regions with non-zero difference values; the coordinate transformation algorithm accurately locates shapes, sizes, and center coordinates of the difference regions by using image processing techniques such as clustering and edge detection.

[0072] The visual detection module outputs a set of quantized error vector data.

[0073] The calibration module reads the quantized error vector data output by the visual detection module, and compensates for subsequent position instructions sent to the galvanometer in real time.

[0074] In an embodiment, the calibration module reversely deduces that an internal cause of the error is a current temperature offset of the X / Y motor, and subtracts a compensation value from X / Y coordinates of all subsequent instructions, so as to "deceive" the galvanometer and enable a biased movement of the galvanometer to finally draw an unbiased track.

[0075] In an embodiment, the marking surface is predefined as 16 regions, denoted as No. 1, No. 2, …, and No. 16 positions.

[0076] Achieve the perfect closed loop from "awareness" to "execution". It not only alarms when the deviation occurs, but also corrects the error online, real-time and actively, and converts the result of each detection into the action of optimizing the next processing, so as to ensure that the equipment can maintain high processing precision in continuous work for a long time.

[0077] With the help of low-cost CMOS image sensing module, the laser galvanometer temperature drift self-checking and correction function is realized under the premise of ensuring the compact structure of the galvanometer.

[0078] Combined with the internal optical path characteristics of the laser galvanometer, the overall processing range is divided into multiple continuous visual single detection areas, and the position drift error of each visual single detection area is detected respectively, which reduces the single calculation and judgment time, improves the real-time performance, and is especially suitable for large-scale continuous step-by-step regional processing applications, that is, it ensures the real-time performance of detection and reduces the calculation amount.

[0079] Through the visual detection module of the laser galvanometer, the comparison between the standard temperature drift reference position and the actual processing reference position is realized, which realizes the calculation and judgment of temperature drift data and provides numerical basis for realizing temperature drift correction of each segmented area, so as to ensure the temperature drift detection and correction of the whole processing range.

[0080] The laser equipment suitable for large-scale long-period continuous processing not only ensures the real-time online temperature drift detection and correction of the laser galvanometer, but also reduces the system cost and the complexity of system design to overcome the problem of galvanometer temperature drift.

[0081] The laser galvanometer with temperature drift self-checking and correction simplifies the temperature drift detection and correction method of laser system trajectory processing precision, and is more flexible and convenient when integrated with laser system.

[0082] The above description is an explanation of the application, not a limitation of the application, the scope defined by the application is referred to the claims, within the protection scope of the application, any form of modification can be made.

Claims

1. A laser galvanometer detection system with temperature drift self-checking and correction, characterized in that, The application relates to an error calibration method for a laser marking system. The application comprises an error judging module and an error calibration module. The error judging module comprises a CMOS image sensing module, a visual detection module and a storage module, and the error calibration module comprises a calibration module and a laser marking module. The CMOS image sensing module is used for shooting high-definition images, and the visual detection module can generate a prediction image and identify the deviation of the image shot by the CMOS image sensing module. The visual detection module is internally provided with a coordinate transformation algorithm.

2. The laser galvanometer detection system with temperature drift self-checking and correction of claim 1, wherein: The laser marking module comprises a galvanometer and a laser.

3. The laser galvanometer detection system with temperature drift self-checking and correction of claim 1, wherein: The method comprises the following steps:

4. The working method of the laser galvanometer detection system with temperature drift self-checking and correction as described in any one of claims 1-3, characterized in that, N regions are defined as No. 1, No. 2, …, and No. N positions, a CMOS image sensing module is driven to move to the N regions in sequence, and the CMOS image sensing module shoots a clear high-definition image at each position and stores the image into a storage module, which is recorded as P1, P2, …, and PN; During the marking process at the No. 1 position, all position instructions POS1 are recorded and stored into the storage module; A visual detection module reads the image P1 and all position instructions POS1, a coordinate transformation algorithm of the visual detection module establishes a mapping model from a "galvanometer instruction coordinate system" to a "CMOS image pixel coordinate system", the coordinate transformation algorithm traverses each position instruction in POS1, calculates the pixel position of a theoretical laser point in the reference image P1 by using the mapping model, and marks all the calculated pixel points on the image P1. The coordinate transformation algorithm marks all the calculated pixel points on the image P1, and stores the marked image P1 into the storage module, which is recorded as K1; A laser marking module receives the position instructions POS1, drives the galvanometer and the laser to process a workpiece, and after the marking is completed, the CMOS image sensing module is accurately positioned back to the No. 1 position, shoots an image of the No. 1 position after the processing, and stores the image into the storage module, which is recorded as M1; A visual detection module reads the images M1 and K1 from the storage module, a coordinate transformation algorithm of the visual detection module identifies the features shared by the images M1 and K1 and not affected by the processing, adjusts the two images to the same coordinate system by calculating the transformation relationship between the features, such as translation and rotation, and then performs a pixel-by-pixel subtraction operation on the images K1 and M1, wherein the non-zero difference area is identified as an abnormal area, and the coordinate transformation algorithm accurately locates the shape, size and center coordinates of the difference area by using image processing technologies such as clustering and edge detection. The visual detection module outputs a set of quantized error vector data. A calibration module reads the quantized error vector data output by the visual detection module and compensates the position instructions sent to the galvanometer in real time. Each feature point in the images P1, P2, …, and PN corresponds to an accurate and known theoretical coordinate in the galvanometer coordinate system.

5. The method of operating a laser galvanometer inspection system with temperature drift self-checking and correction as defined in claim 4, wherein: Each feature point in the images P1, P2, …, and PN comprises a mark on the workpiece, an edge of a clamp and a pre-prepared standard target.

6. The method of operating a laser galvanometer inspection system with temperature drift self-checking and correction as claimed in claim 5, wherein: ​ 7. The method of operating a laser galvanometer inspection system with temperature drift self-checking and correction as defined in claim 4, wherein: the temperature drift self-checking and correction is performed by the controller. The calibration module reversely deduces the internal cause leading to the error as the current temperature offset of the X / Y motor, and subtracts a compensation value from all subsequent X / Y coordinates, thereby "cheating" the galvanometer so that the biased movement of the galvanometer can finally draw an unbiased track.

8. The method of operating a laser galvanometer inspection system with temperature drift self-checking and correction of claim 4, wherein: The calibration module converts the deviation pixels into instruction deviations, and generates a corresponding table through the installation and debugging process.

9. The method of operating a laser galvanometer inspection system with self-checking, correction of temperature drift as claimed in claim 8, wherein: The calibration module generates a position instruction calibration table by adding a deviation value to the original instruction.

10. The method of operating a laser galvanometer inspection system with self-checking, correction of temperature drift as claimed in claim 9, wherein: In subsequent laser marking, the instruction calibration table is added to the original instruction to generate a new instruction, which is sent to the laser marking module; and the laser marking module performs marking.

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