Calibration method and device of laser space scanning device and laser marking method

Abstract

The invention relates to a calibration method and device of a laser space scanning device and a laser marking method. The method comprises the following steps: for each target focus point in a target focus point set, determining reference control data of a laser galvanometer according to the target focus points; controlling the laser galvanometer to emit laser according to the reference control data; controlling the camera to move so that the imaging center of the camera is located at the target focus point; the control data of the laser galvanometer are adjusted, so that the light spot of the laser is focused at the imaging center, and corresponding target control data are obtained; determining a spatial data relationship based on the target control data and the corresponding target focus points; the spatial data relation is used for determining corresponding target control data according to the position of the to-be-processed point so as to carry out laser marking. By adopting the method, calibration errors can be reduced.

Description

Technical Field

[0001] The present application relates to the field of laser marking technology, and in particular to a calibration method, device and laser marking method for a laser space scanning device. Background Art

[0002] The laser space scanning device is a system that combines a laser, a high-speed scanning galvanometer, and a dynamic focusing device. It is an optical refraction and reflection device that can accurately control the optical path of the laser beam. The continuous improvement of the manufacturing level of the laser galvanometer has made a qualitative leap in the scanning positioning accuracy and scanning speed. The structure has expanded from the early flat laser marking processing to high-precision three-dimensional curved surface laser processing, laser 3D positioning projection, laser 3D scanning, laser dynamic tracking and many other aspects. Laser marking has the advantages of fast marking speed, high clarity and convenience for precise marking, so it is widely used in many industries such as electronics, medical care, and automobiles. The traditional method is to mark the marking points on the photosensitive medium, and use the deviation between the theoretical coordinate value and the actual coordinate value of the marking point as the compensation value to correct the marking data. However, the calibration error of the traditional calibration method is large. Summary of the invention

[0003] Based on this, it is necessary to provide a calibration method, device and laser marking method for a laser space scanning device that can reduce calibration errors in order to solve the above technical problems.

[0004] A calibration method for a laser space scanning device, the method comprising:

[0005] For each target focus point in the target focus point set, determining reference control data of the laser galvanometer according to the target focus point;

[0006] Controlling the laser galvanometer to emit laser light using the reference control data;

[0007] Controlling the movement of the camera so that the imaging center of the camera is located at the target focusing point;

[0008] Adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center to obtain corresponding target control data;

[0009] A spatial data relationship is determined based on the target control data and the corresponding target focus points; the spatial data relationship is used to determine the corresponding target control data according to the position of the point to be processed, so as to perform laser marking.

[0010] A laser marking method, applied to a laser space scanning device, comprising:

[0011] Get the position of the point to be processed;

[0012] Determine the target control data corresponding to the position of the to-be-processed point based on the spatial data relationship;

[0013] Controlling the laser galvanometer to perform laser marking based on the target control data;

[0014] Among them, the spatial data relationship is determined based on each focusing point in the focusing point set and the control data corresponding to each focusing point; the control data corresponding to each focusing point is obtained by adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center of the camera; the imaging center of the camera is located at the focusing point; the laser is emitted by the laser galvanometer with the reference control data determined by the focusing point.

[0015] A laser space scanning device comprises a processor, a laser galvanometer and a camera, wherein the processor is connected to the laser galvanometer and the camera respectively; the processor is used to implement the steps of the calibration method embodiment of each laser space scanning device.

[0016] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of an embodiment of a calibration method for each laser space scanning device when executing the computer program.

[0017] A computer-readable storage medium stores a computer program, which implements the steps of the calibration method embodiment of each laser space scanning device when the computer program is executed by a processor.

[0018] The calibration method, device and laser marking method of the above-mentioned laser space scanning device are not necessarily accurate according to the reference control data determined by the target focusing point. Therefore, the light spot presented by the laser emitted by the laser galvanometer controlled by the reference control data may not be located at the target focusing point. The camera is controlled to move until the imaging center is located at the target focusing point, thereby ensuring the accuracy of the target focusing point acquisition and avoiding the distortion error of the camera. Compared with the method of using photosensitive media for marking and then calibrating, the light spot is directly acquired by the camera, and there is no calibration medium, which reduces the intermediate variables of the calibration and thus reduces the introduction of errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure and operation of a laser space scanning device in one embodiment;

[0020] Figure 2 A schematic diagram of a microscopic state of a laser beam scanning operation in one embodiment;

[0021] Figure 3 is a schematic structural diagram of a laser space scanning device in one embodiment;

[0022] Figure 4A schematic diagram of a flow chart of a calibration method for a laser space scanning device in one embodiment;

[0023] Figure 5 A schematic diagram of the distribution of target focusing points in a target focusing point set in one embodiment;

[0024] Figure 6 A schematic diagram of adjusting the position of the light spot center at the imaging center in one embodiment;

[0025] Figure 7 A schematic diagram of a process of a laser marking method in one embodiment;

[0026] Figure 8 A schematic diagram of the principle of trilinear interpolation in one embodiment;

[0027] Fig. 9 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0028] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. The connection can be a direct connection or an indirect connection.

[0031] In addition, in this application, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0032] The terms "first", "second", etc. used in this application may be used herein to describe various data, but these data are not limited by these terms. These terms are only used to distinguish a first data from another data. For example, without departing from the scope of this application, a first distance may be referred to as a second distance, and similarly, a second distance may be referred to as a first distance. Both the first distance and the second distance are distances, but they are not the same distance.

[0033] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0034] In one embodiment, Figure 1 The figure shows a schematic diagram of the structure and operation of a laser space scanning device in an embodiment. The laser space scanning device includes a laser emitter 1.1, a dynamic focusing device 1.2, a first laser galvanometer 1.3, and a second laser galvanometer 1.4. When the device processes a control point P, a laser beam 1.5 is emitted by the laser generator 1.1, and the laser beam 1.5 changes the focal length (zΔ) of the beam through the dynamic focusing device 1.2, so that it is focused at different optical paths. The laser beam 1.5 passes through the galvanometer rotation angle (α) indicated by the first laser galvanometer 1.3, thereby changing the position of the focus in the X-axis direction. The laser beam 1.5 passes through the galvanometer rotation angle (β) indicated by the second laser galvanometer 1.4, thereby changing the position of the focus in the Y-axis direction. Finally, the focal point of the laser beam 1.5 falls within the space of the scanning range 1.6.

[0035] Note: In theory, the two galvanometers are in the initial state, that is, the rotation angles of the two galvanometers are both 0, and the light beam is perpendicular to the horizontal plane. The position of the light beam at this time is defined as the origin of the laser galvanometer system (Xo, Yo, Z), where Z will change under the action of the dynamic focusing structure, but Xo and Yo remain unchanged.

[0036] Figure 2 Schematic diagram of the microscopic state of laser beam scanning in one embodiment. 2.2 refers to the position of the laser scanning target point, 2.1 refers to the theoretical laser beam arrival position, 2.3 refers to the actual laser beam arrival position, and d indicates that within this range, the focusing effect can achieve the required scanning (processing) requirements. Figure 2 Analysis shows that accurate beam direction is a prerequisite for effective processing. Figure 1 As can be seen from the content, the laser galvanometer determines the direction of the laser beam, so calibrating the galvanometer is a prerequisite for ensuring the accuracy of laser processing.

[0037] Figure 3 Schematic diagram of the structure of a laser space scanning device in one embodiment. Figure 3The system includes a high-precision motion platform 3.1, a laser galvanometer 3.2, a three-axis CNC probe 3.3 and a high-resolution camera 3.4. The high-precision motion platform can be a five-axis motion platform, and the three-axis CNC probe 3.3 and the high-resolution camera 3.4 are installed on the high-precision motion platform 3.1. In the calibration process, the high-resolution camera 3.4 receives the laser emitted by the laser galvanometer 3.2 and forms an image.

[0038] In one embodiment, Figure 4 FIG. 1 is a flow chart of a calibration method for a laser space scanning device in an embodiment, which is applied to Figure 3 The laser space scanning device shown includes a processor, a laser galvanometer, a motion platform and a camera. The method includes the following steps:

[0039] Step 402: for each target focus point in the target focus point set, determine reference control data of the laser galvanometer according to the target focus point.

[0040] Among them, the range that needs to be corrected and the point spacing are defined to form a target focus point set. The target focus point P (x, y, z) is the point where the laser emitted by the laser galvanometer is expected to focus, which is a theoretical value. Different target focus points include target focus points on different planes. The control data of the laser galvanometer refers to the data used to control the laser galvanometer to emit lasers, and may include a first control angle α, a second control angle β and a focal length F. The reference control data of the laser galvanometer is used to control the laser galvanometer so that its laser spot converges to the target focus point.

[0041] Since the physical quantity of the parameter received by the galvanometer is the angle of rotation of the galvanometer, and the physical quantity of the dynamic focusing parameter is the focal length, there are three parameters when controlling the light spot to point P: α, β and F. The other three quantities represent the control of the x, y, and z directions respectively. The spatial coordinate calculation process of the target focus point P is obtained by the following formula:

[0042]

[0043] In the above formula, e and H are known quantities, representing the center distance between the galvanometers and the initial focusing focal length respectively. The reference control parameters calculated by the above formula are used to control the laser galvanometer to emit a laser beam so that the focusing point is P.

[0044] Step 404, controlling the laser galvanometer to emit laser light according to the reference control data.

[0045] Specifically, the laser space scanning device controls the laser galvanometer to emit a laser beam with the reference control data. In theory, the focal point of the laser galvanometer should be at the position of the target focal point.

[0046] Step 406, controlling the camera to move so that the imaging center of the camera is located at the target focus point.

[0047] Specifically, the processor controls the motion platform to drive the camera to move so that the imaging center of the camera is located at the target focus point, and the laser spot is imaged in the camera at this time. It can be understood that due to the large photosensitive area of ​​the camera, the error of the laser galvanometer is also controlled within a certain range when leaving the factory, so as to ensure that the laser spot can be imaged smoothly in the camera at this time.

[0048] Step 408, adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center to obtain corresponding target control data.

[0049] The laser is directed to the camera, and the laser spot is formed at the imaging center of the camera, which means that the camera is used as the imaging medium of the laser galvanometer, and there is no intermediate medium. In addition, the power of the laser should be less than the maximum acceptable power of the camera; and the use of this power will neither damage the camera nor leave marks at the focus.

[0050] Specifically, in theory, the laser spot will be shot into the pixel center of the camera imaging at the position of the target focal point P (x, y, z) and focused. However, due to installation reasons such as processing, there are certain errors, that is, the calculated parameters will actually be offset on the target focal point P. The control data of the laser galvanometer such as α, β and F are adjusted iteratively by binary division, so that the laser spot is focused at the imaging center, that is, coincides with the imaging center, and the corresponding target control data is obtained. The corresponding target control data is the data that makes the spot focus on the imaging center.

[0051] Step 410, determining a spatial data relationship based on the target control data and the corresponding target focus points; the spatial data relationship is used to determine the corresponding target control data according to the position of the point to be processed, so as to perform laser marking.

[0052] The spatial data relationship includes standard target control data and corresponding target focus point (ie, actual marking position). The spatial data relationship represents an interpolation correction table within a specified marking space range.

[0053] Specifically, the target control data and the corresponding target focus point are mapped to obtain a spatial data relationship. After successful calibration, when laser marking is performed, the laser space scanning device searches for the spatial data relationship, determines the corresponding target control data according to the position of the point to be processed, and controls the laser galvanometer to perform laser marking based on the target control data.

[0054] In this embodiment, Figure 5 , which is a schematic diagram of the distribution of target focusing points in a target focusing point set in one embodiment. Figure 5The target focus points are distributed in space, and at least one of the x, y and z coordinate values ​​of each target focus point is the same. Since the target focus points can be set arbitrarily in a large spatial range, there is no size limit for the calibration medium, which greatly increases the amount of calibration data.

[0055] In this embodiment, the reference control data determined according to the target focus point is not necessarily accurate. Therefore, the light spot presented by the laser emitted by the laser galvanometer controlled by the reference control data may not be located at the target focus point. The camera is controlled to move until the imaging center is located at the target focus point, thereby ensuring the accuracy of target focus point acquisition and avoiding camera distortion errors. Compared with the method of using photosensitive media for marking and then calibrating, the light spot is directly acquired by the camera without calibration media, which reduces the intermediate variables of calibration and thus reduces the introduction of errors. In addition, since the target focus point set is no longer limited by the calibration medium, the calibration range is greatly improved.

[0056] In one embodiment, the traditional method requires indirect measurement using photosensitive media through multiple two-dimensional plane calibration, which undoubtedly introduces new errors. At the same time, it is necessary to strictly require the horizontal installation of the photosensitive medium, otherwise the error will be amplified; due to the existence of the focal depth of the light beam, the two-dimensional photosensitive medium cannot find the best focusing position, resulting in unstable spot size that may occur in subsequent processing. Therefore, the method in this embodiment is proposed, which adjusts the control data of the laser galvanometer so that the laser spot is focused at the imaging center and obtains the corresponding target control data, including: obtaining the spot center of the spot; according to the first distance between the spot center and the imaging center, adjusting the control data of the laser galvanometer so that the spot area is minimized and the spot center is located at the imaging center, and obtaining the corresponding target control data.

[0057] Specifically, the spot center of the light spot is obtained by fine-tuning. According to the distance between the spot center and the imaging center, the distance can be a vector used to indicate the adjustment direction and adjustment amplitude of the light spot. It can be understood that the change of the control data of the laser galvanometer will change the position of the spot center. The control data may include a first control angle α, a second control angle β and a focal length F. By adjusting the control data, the spot area can be minimized and the spot center can be located at the imaging center. In addition, the laser space scanning device can obtain the position of the imaging center in the image, as well as the position of the spot center in the image, so it is easy to obtain the distance between the spot center and the imaging center.

[0058] like Figure 6The figure shows a schematic diagram of adjusting the position of the light spot center at the imaging center in an embodiment. Theoretically, the light spot center should fall on P, but in fact the light spot focus position (light spot center) is at P', and the light spot position under focus is Pi at the camera imaging position. The image algorithm is used to calculate the error from the light spot at the Pi position to the target focus point P, so as to adjust the XY direction, calculate the light spot area at Pi under focus, and adjust the focal length until the laser light spot is focused at the camera imaging center and the centers of the two coincide.

[0059] In this embodiment, according to the first distance between the center of the light spot and the target focusing point, the control data of the laser galvanometer is adjusted so that the light spot area is minimized and the center of the light spot is located at the imaging center, so that the optimal position parameters and the optimal focusing parameters can be obtained at the same time; and because the smaller the light spot, the smaller the error of the center of the light spot, the calibration accuracy can be improved; and each light spot is close to the optimal focusing state, and the focusing effect is better and more uniform during processing.

[0060] In one embodiment, according to the first distance between the center of the light spot and the imaging center, the control data of the laser galvanometer is adjusted so that the light spot area is minimized and the center of the light spot is located at the imaging center, and the corresponding target control data is obtained, including:

[0061] Adjusting control data of the laser galvanometer according to a first distance between the center of the light spot and the imaging center so that the center of the light spot is located at the imaging center;

[0062] Adjust the focal length of the laser galvanometer so that the spot area at the imaging center is minimized to obtain the minimum spot;

[0063] Acquire the spot center of the minimum spot, and determine a second distance between the spot center of the minimum spot and the imaging center;

[0064] When the second distance is greater than the preset distance, return to the step of adjusting the control data of the laser galvanometer according to the first distance between the center of the light spot and the imaging center so that the center of the light spot is located at the imaging center, until the second distance is less than or equal to the preset distance, and obtain the corresponding target control data.

[0065] Specifically, the control data of the laser galvanometer is adjusted according to the first distance between the center of the light spot and the imaging center, so that the center of the light spot is located at the imaging center; and the light beam at this time may not correspond to the optimal focusing parameter, so by adjusting the focal length of the laser galvanometer, the area of ​​the light spot located at the imaging center is minimized, indicating that the corresponding focal length is the most accurate focal length. However, since the center position of the light spot may change slightly due to the change in focal length, it is necessary to determine the second distance between the center of the light spot of the minimum light spot and the imaging center. When the second distance is greater than the preset distance, return to the step of adjusting the control data of the laser galvanometer according to the distance between the center of the light spot and the imaging, so that the center of the light spot is located at the imaging center, until the second distance is less than or equal to the preset distance, then it is determined that the area of ​​the light spot is the smallest and the center of the light spot is located at the imaging center, and the target control data at this time is obtained.

[0066] In this embodiment, the control data of the laser galvanometer is adjusted according to the first distance between the center of the light spot and the imaging center, so that the center of the light spot is located at the imaging center; the focal length of the laser galvanometer is adjusted to minimize the area of ​​the light spot located at the imaging center to obtain the minimum light spot, and then the control data is adjusted according to the second distance between the minimum light spot and the imaging center. This can make the laser focus on the imaging center and the target focal point, make the calibration more accurate, and achieve higher precision in marking using a laser galvanometer.

[0067] In one embodiment, obtaining the spot center of the light spot includes: obtaining a spot image of the light spot; performing filtering and smoothing on the spot image, and then performing binarization to obtain a binary image; obtaining a connected domain in the binary image, determining a central pixel of the connected domain, and obtaining the spot center.

[0068] Specifically, the laser space scanning device collects the spot image of the spot through a camera, performs filtering and smoothing on the spot image, and then performs binarization to obtain a binary image containing the spot. The connected domain in the binary image is obtained through an image processing algorithm, and the central pixel of the connected domain is determined to obtain the coordinates of the center of the spot. Subsequently, the first distance can be determined based on the coordinates of the center of the spot and the coordinates of the imaging center.

[0069] In this embodiment, by acquiring a spot image of the light spot, filtering and smoothing the spot image and then binarizing it to obtain a binary image, a clearer light spot can be displayed; by acquiring a connected domain in the binary image and determining the central pixel of the connected domain, the center of the light spot can be obtained, and then the laser space scanning device can be calibrated.

[0070] In one embodiment, obtaining the spot center of the light spot includes: obtaining a spot image of the light spot; performing filtering and smoothing on the spot image, and then performing binarization to obtain a binary image; obtaining a connected domain in the binary image, determining a central pixel of the connected domain, and obtaining the spot center.

[0071] The mechanical structure parameters of the camera may include the length and width of the camera, the distance between the camera clamping position and the imaging center, etc.

[0072] Specifically, the coordinates of the target focus point are the coordinates of the machine tool coordinate system. The probe is used to detect the clamping position of the camera in the machine tool coordinate system, and the distance from the camera clamping position to the imaging center is added to the camera clamping position to obtain the imaging center of the camera in the machine tool coordinate system. Therefore, the pixel coordinates can also be converted into the coordinates of the machine tool coordinate system. The laser space scanning device controls the movement of the camera and moves the camera from the current imaging center to the target focus point. In the next movement, it can move from the previous target focus point to the next target focus point.

[0073] In this embodiment, a probe is used to detect the clamping position of the camera, and the current imaging center of the camera is determined based on the mechanical structure parameters and the clamping position of the camera. The camera movement is controlled to move the camera from the current imaging center to the target focusing point. The camera position is determined in combination with a high-precision motion platform to ensure spatial data accuracy.

[0074] In one embodiment, the power of the laser is less than the maximum acceptable power of the camera. Specifically, the maximum acceptable power of the camera refers to the power that can be captured by the camera without damaging the internal components of the camera. The laser with this power can directly illuminate the camera without the need for calibration through a calibration medium, thereby reducing intermediate variables and reducing the introduction of errors.

[0075] In one embodiment, Figure 7 FIG. 1 is a flow chart of a laser marking method in an embodiment, and takes the method applied to a laser space scanning device as an example, and includes the following steps:

[0076] Step 702, obtaining the position of the point to be processed.

[0077] Specifically, the position of the point to be processed refers to the actual position of the point to be processed in space, that is, the target position required by the user. For example, it can be the position in the laser coordinate system or the machine tool coordinate system, and the laser coordinate system can be the world coordinate system, the workpiece coordinate system or other custom coordinate systems.

[0078] Step 704: determine the target control data corresponding to the position of the to-be-processed point based on the spatial data relationship.

[0079] Among them, the spatial data relationship is determined based on the focus points in the focus point set and the control data corresponding to each focus point; the control data corresponding to each focus point is obtained by adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center of the camera; the imaging center of the camera is located at the focus point; the laser is emitted by the laser galvanometer with the reference control data determined by the focus point.

[0080] Specifically, the spatial data relationship records the mapping relationship between the spatial position of the focus point and the control data. Therefore, the laser spatial scanning device performs trilinear interpolation based on the spatial data relationship and the position of the point to be processed to obtain the target control data corresponding to the position of the point to be processed. Specifically, the area in the relationship corresponding to the position of the point to be processed can be determined, and trilinear interpolation is performed based on 8 points adjacent to the position of the point to be processed to determine the target control data corresponding to the position of the point to be processed.

[0081] Step 706, controlling the laser galvanometer to perform laser marking based on the target control data.

[0082] Specifically, the laser space scanning device sets the control parameters of the laser galvanometer as target control data and then performs laser marking, so that the marking point is located at the position of the point to be processed.

[0083] In this embodiment, the position of the point to be processed is obtained, the target control data corresponding to the position of the point to be processed is determined based on the spatial data relationship, and the laser galvanometer is controlled to perform laser marking based on the target control data. That is, the control data is directly found through the spatial data relationship, which enables the laser galvanometer to mark at the position indicated by the position of the point to be processed. There are fewer intermediate process conversions, which improves the accuracy of laser marking.

[0084] In one embodiment, a traditional laser space scanning device uses the deviation between the theoretical coordinate value and the actual coordinate value printed on the calibration medium as compensation to calibrate the laser space scanning device. However, this method will be affected by the image spacing of the pattern array. When this spacing is too large, the marked pattern will have obvious gridding and discontinuity.

[0085] In addition, the indirect measurement through multiple two-dimensional plane calibration requires the use of photosensitive media, which undoubtedly introduces new errors. At the same time, it is necessary to strictly require the horizontal installation of the photosensitive medium, otherwise the error will be amplified; due to the existence of the focal depth of the light beam, the two-dimensional photosensitive medium cannot find the best focusing position, resulting in unstable spot size in subsequent processing.

[0086] In addition, the above schemes can achieve high accuracy in two-dimensional calibration. However, when used for spatial calibration (dividing the spatial calibration range into multiple two-dimensional planes for calibration), they all ignore a problem: due to installation accuracy issues, the galvanometer itself has already undergone a certain deflection in the initial state. According to the mathematical model of the laser galvanometer system, it can be determined that this will cause the origin position of the light beam at different heights to be different or even non-collinear. This causes the calculated calibration data to jump during spatial calibration, and the accuracy cannot be guaranteed.

[0087] Therefore, a calibration method for the laser control scanning device in the embodiment of the present application is proposed. In this embodiment, a high-precision motion platform is combined with a camera assembly and a high-precision motion platform to collect spatial point coordinates, and by obtaining the relationship between the corresponding control data {(α, β, zΔ)|α∈Rα, β∈Rβ, zΔ∈RzΔ} and the focus point set {(x, y, z)|x∈Rx, y∈Ry, z∈Rz}, a spatial interpolation model is established to perform high-precision control marking (Rα…Rz refers to the range set of the corresponding quantity in the real number domain).

[0088] To be applied to Figure 3 The laser space scanning device is used as an example to briefly explain: fix the camera on the five-axis platform, establish the relationship between the camera imaging pixel center and the machine tool coordinate system through camera parameters and high-precision three-axis probe; control the laser device and motion platform to make the laser spot image in the camera; dynamically adjust the control parameters to make the spot in the camera smallest and the pixel coordinates of the center of the spot at the imaging center; construct a spatial interpolation correction table based on the collected grid control information to achieve correction. The specific implementation steps are as follows:

[0089] Step 1: Establish the relationship between the camera imaging center and the machine tool coordinate system. The specific implementation steps are as follows:

[0090] Use a fixing device to fix the camera on the motion platform, and then use a three-axis CNC probe to obtain the clamping position of the camera. After obtaining the camera clamping position, combined with the camera mechanical structure parameters, the position relationship of the camera imaging center in the machine tool coordinate system is obtained.

[0091] Step 2: Control the laser space scanning device and the motion platform so that the laser spot is imaged in the camera. The specific implementation is as follows:

[0092] The laser device is controlled to focus the laser spot at the spatial point P (x, y, z). Since the parameter physical quantity received by the galvanometer is the angle of rotation of the galvanometer, and the dynamic focusing parameter physical quantity is the focal length, there are three parameters, α, β, and F, when controlling the spot to point P. The other three quantities represent the control of the x, y, and z directions respectively. The spatial coordinate calculation process of the point P to be controlled is obtained by the following formula:

[0093]

[0094] In the above formula, e and H are known quantities, representing the center distance between the galvanometers and the initial focus focal length, respectively. The control parameters calculated by the above formula are used to control the laser device to emit a laser beam so that the focus point is P. Then the motion platform is controlled so that the center of the camera's imaging pixel is at the position of the spatial point P. Since the camera has a large photosensitive area, the error of the laser galvanometer is also controlled within a certain range when it leaves the factory, so that it can be guaranteed that the laser spot can be smoothly imaged in the camera at this time.

[0095] Step 3: Dynamically adjust the control parameters to minimize the light spot in the camera and make the pixel coordinates of the center of the light spot at the imaging center. The specific implementation is as follows:

[0096] Theoretically, through the above steps, the laser spot will be shot into the pixel center of the camera imaging at this position and focused. However, due to processing and other installation reasons, there is a certain error, that is, the calculated parameters will actually shift on the coordinate P to be controlled. The three control parameters α, β, and F are adjusted iteratively through the dichotomy method. The adjustment process is as follows: Figure 6 As shown, theoretically the spot position should fall on P, but in fact the spot focus position is P', and the spot position under focus is Pi at the camera imaging position. The image algorithm is used to calculate the error from the spot at position Pi to position P, so as to adjust the XY direction, calculate Pi and the spot size under focus, and adjust the focal length until the laser spot is focused at the camera imaging center and the center coincides.

[0097] In the above process, the algorithm flow for judging the focus of the light spot and the coincidence of the center of the light spot with the center of the image formed by the camera is as follows: using a filtering algorithm to reduce noise and smooth the image; converting the binary image to obtain a connected domain; calculating the size of the light spot and the pixel coordinates of the center of the light spot; calculating the light spot adjustment vector (i.e., representing the distance between the two) based on the pixel coordinates of the imaging center and the center of the light spot; and when the modulus of the light spot adjustment vector is less than the preset distance, determining that the imaging center and the center of the light spot coincide.

[0098] Step 4: Construct a spatial interpolation correction table based on the collected grid control information to achieve correction, which is implemented as follows:

[0099] Define the range and point spacing to be corrected, obtain the focus point set, repeat the above steps 1, 2, and 3 to achieve the spatial array point (such as Figure 6As shown in the figure, the control of the galvanometer system is completed, thereby completing the data collection of the galvanometer system control data set {(α, β, zΔ)|α∈Rα, β∈Rβ, zΔ∈RzΔ} and the actual marked spatial point set {(x, y, z)|x∈Rx, y∈Ry, z∈Rz}. Let the actual marking function of the galvanometer system be (x, y, z)=f(α, β, zΔ), then the above steps complete a series of point collections of this function, and all are real data. The actual marked coordinate information and the galvanometer control data issued by the actual control are used to construct an interpolation correction table for the specified calibration space range.

[0100] After completing the calibration table construction, you can use the calibration table for subsequent marking work. The implementation steps are as follows:

[0101] a. When calibrating the processing point, locate the area in the calibration table where the position is surrounded by multiple points collected in the calibration table, such as Figure 8 FIG. 1 is a schematic diagram of the principle of trilinear interpolation in an embodiment, for calibrating the point P to be processed.

[0102] b. Use the 8 vertex data of its positioning grid for calibration (the grid is a cube).

[0103] c. Use the positioning data to perform trilinear interpolation to find the laser data that should be sent to mark point P.

[0104] The method in this embodiment was used to carry out a laser galvanometer system calibration experiment, and the calibration error was ±2um, which can correct the laser marking points, verifying the feasibility and accuracy of this embodiment.

[0105] The method in this embodiment has the following advantages:

[0106] ① It is mounted on a high-precision motion platform, such as a three-axis machine tool or a five-axis machine tool, so that the data accuracy in the XYZ direction can be guaranteed during the calibration process when collecting calibration data.

[0107] ② This embodiment combines the motion platform and the camera for data collection. Compared with the method of marking with a photosensitive medium and then calibrating, the calibration range is greatly improved, while the intermediate variables are reduced and the introduction of errors is reduced.

[0108] ③ Each collected light spot is close to the optimal focusing state, and the focusing effect is better and more uniform during processing.

[0109] ④ Compared with the existing solutions that use a monocular camera or a binocular camera to obtain images for direct calibration, in this embodiment, the center of the light spot is directly aligned with the center of the camera, and there is no need to correct the distortion of the camera, so the imaging effect is less affected.

[0110] ⑤ When determining the final correction data, the data used in this embodiment are the actual measurement coordinate information and the real laser galvanometer control parameters. Compared with the solution using compensation values ​​for correction, it will not be limited by the grid size, and the marked pattern will be smoother; and even if the laser galvanometer itself is not installed completely vertically, the laser can be directly shot to the target focal point based on the target control data, rather than through offset and other methods, to improve the laser marking accuracy.

[0111] ⑥ The use of motion platform, camera components and visual algorithm linkage makes the entire calibration process fully automated and intelligent, improving the calibration efficiency and accuracy of the laser galvanometer system.

[0112] In one embodiment, a calibration method for a laser space scanning device includes the following steps:

[0113] Step (a1), for each target focusing point in the target focusing point set, determining reference control data of the laser galvanometer according to the target focusing point.

[0114] Step (a2), controlling the laser galvanometer to emit laser light with reference control data, wherein the power of the laser light is less than the maximum acceptable power of the camera.

[0115] Step (a3), using a probe to detect the clamping position of the camera.

[0116] Step (a4), determining the current imaging center of the camera based on the mechanical structure parameters and the clamping position of the camera.

[0117] Step (a5), controlling the motion platform to drive the camera to move, and moving the camera from the current imaging center to the target focusing point.

[0118] Step (a6), obtaining a spot image of the light spot.

[0119] Step (a7), after filtering and smoothing the spot image, binarization is performed to obtain a binary image.

[0120] Step (a8), obtaining a connected domain in the binary image, determining the central pixel of the connected domain, and obtaining the center of the light spot.

[0121] Step (a9), adjusting the control data of the laser galvanometer according to the first distance between the center of the light spot and the imaging center so that the center of the light spot is located at the imaging center.

[0122] Step (a10), adjusting the focal length of the laser galvanometer so that the spot area at the imaging center is minimized to obtain the minimum spot.

[0123] Step (a11), obtaining the spot center of the minimum spot, and determining a second distance between the spot center of the minimum spot and the imaging center.

[0124] Step (a12), when the second distance is greater than the preset distance, return to the control data of the laser galvanometer according to the first distance between the center of the light spot and the imaging center, so that the center of the light spot is located at the imaging center step, until the second distance is less than or equal to the preset distance, and obtain the corresponding target control data.

[0125] Step (a13), determining the spatial data relationship based on the target control data and the corresponding target focus points; the spatial data relationship is used to determine the corresponding target control data according to the position of the point to be processed for laser marking.

[0126] In this embodiment, the reference control data determined according to the target focus point is not necessarily accurate. Therefore, the light spot presented by the laser emitted by the laser galvanometer controlled by the reference control data may not be located at the target focus point. The camera is controlled to move until the imaging center is located at the target focus point, thereby ensuring the accuracy of target focus point acquisition and avoiding camera distortion errors. Compared with the method of using photosensitive media for marking and then calibrating, the light spot is directly acquired by the camera without calibration media, which reduces the intermediate variables of calibration and thus reduces the introduction of errors. In addition, since the target focus point set is no longer limited by the calibration medium, the calibration range is greatly improved.

[0127] It should be understood that although the above Figure 4 and 7 The steps in the flowchart are shown in sequence as indicated by arrows, and the steps in steps (a1) to (a13) are shown in sequence as indicated by numbers, but these steps are not necessarily performed in the order indicated by arrows or numbers. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be performed in other orders. Moreover, Figure 4 and Figure 7 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0128] A laser space scanning device comprises a processor, a laser galvanometer motion platform and a camera. The processor is connected to the laser galvanometer, the motion platform and the camera respectively. When the processor executes a computer program, the steps of the above-mentioned method embodiments are implemented.

[0129] For the specific definition of the laser space scanning device, please refer to the definition of the calibration method of the laser space scanning device above, which will not be repeated here. Each module in the above-mentioned laser space scanning device can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0130] In one embodiment, a computer device is provided. The computer device may be a terminal device, and its internal structure diagram may be as follows: Fig. 9 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WiFi, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a calibration method for a laser space scanning device is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0131] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0132] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps of the above-mentioned method embodiments when executing the computer program.

[0133] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method embodiments are implemented.

[0134] In one embodiment, a computer program product or computer program is provided, the computer program product or computer program includes computer instructions, the computer instructions are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps in the above-mentioned method embodiments.

[0135] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes in the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0136] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A calibration method for a laser space scanning device, characterized in that: The method comprises: For each target focus point in the target focus point set, determining reference control data of the laser galvanometer according to the target focus point; Controlling the laser galvanometer to emit laser light using the reference control data; Controlling the movement of the camera so that the imaging center of the camera is located at the target focusing point; Adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center to obtain corresponding target control data; A spatial data relationship is determined based on the target control data and the corresponding target focus points; the spatial data relationship is used to determine the corresponding target control data according to the position of the point to be processed, so as to perform laser marking.

2. The method according to claim 1, characterized in that The step of adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center and obtaining corresponding target control data includes: Get the spot center of the light spot; According to the first distance between the center of the light spot and the imaging center, the control data of the laser galvanometer is adjusted so that the area of ​​the light spot is minimized and the center of the light spot is located at the imaging center, and the corresponding target control data is obtained.

3. The method according to claim 2, characterized in that The step of adjusting the control data of the laser galvanometer according to the first distance between the center of the light spot and the imaging center so that the area of ​​the light spot is minimized and the center of the light spot is located at the imaging center, and obtaining corresponding target control data includes: Adjusting control data of the laser galvanometer according to a first distance between the center of the light spot and the imaging center so that the center of the light spot is located at the imaging center; Adjusting the focal length of the laser galvanometer so that the spot area at the imaging center is minimized to obtain a minimum spot; Acquire the spot center of the minimum spot, and determine a second distance between the spot center of the minimum spot and the imaging center; When the second distance is greater than the preset distance, return to execute the step of adjusting the control data of the laser galvanometer according to the first distance between the center of the light spot and the imaging center so that the center of the light spot is located at the imaging center, until the second distance is less than or equal to the preset distance, and obtain the corresponding target control data.

4. The method according to claim 2, characterized in that: The step of obtaining the center of the light spot comprises: Acquire a spot image of the light spot; After filtering and smoothing the light spot image, binarization is performed to obtain a binarized image; A connected domain in the binary image is obtained, a central pixel of the connected domain is determined, and a light spot center is obtained.

5. The method according to any one of claims 1 to 4, characterized in that: The camera is fixed on a motion platform; the method further comprises: Using a probe to detect the clamping position of the camera; Determining a current imaging center of the camera based on the mechanical structure parameters of the camera and the clamping position; The step of controlling the camera to move so that the imaging center of the camera is located at the target focusing point includes: The motion platform is controlled to drive the camera to move, and the camera is moved from the current imaging center to the target focusing point.

6. The method according to any one of claims 1 to 4, characterized in that: The power of the laser is less than the maximum acceptable power of the camera.

7. A laser marking method, characterized in that: Applied to a laser space scanning device, the method comprises: Get the position of the point to be processed; Determine the target control data corresponding to the position of the to-be-processed point based on the spatial data relationship; Controlling the laser galvanometer to perform laser marking based on the target control data; Among them, the spatial data relationship is determined based on each focusing point in the focusing point set and the control data corresponding to each focusing point; the control data corresponding to each focusing point is obtained by adjusting the control data of the laser galvanometer so that the laser spot is focused at the imaging center of the camera; the imaging center of the camera is located at the focusing point; the laser is emitted by the laser galvanometer with the reference control data determined by the focusing point.

8. A laser space scanning device, characterized in that: The device comprises a processor, a laser galvanometer motion platform and a camera, wherein the processor is connected to the laser galvanometer, the motion platform and the camera respectively, and the processor is used to implement the steps of the method described in any one of claims 1 to 7.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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