Method for detecting focal length of laser head light emission signal and related device

Abstract

The application relates to the field of laser welding. The application discloses a laser head light emission signal focal length detection method and related equipment. The method comprises the following steps: an industrial computer obtains a plurality of detection points formed by a detection light used by a laser head on a workpiece surface, controls the laser head to move up and down during the formation of the plurality of detection points on the workpiece surface, and records the corresponding relationship between the distance between the laser head and the workpiece surface when each detection point is formed and each detection point; and the industrial computer determines the distance corresponding to the smallest detection point in the plurality of detection points as the focal length of the laser head light emission signal. The application is beneficial to improving the accuracy of the focal length of the laser head light emission signal.

Description

Technical Field

[0001] This application relates to the field of laser welding technology, and in particular to a method and related equipment for detecting the focal length of a laser head's output signal. Background Technology

[0002] Existing technologies, such as the optical calibration method and related apparatus described in Chinese patent CN202410167371.2, use laser focus measurement systems to measure the defocusing amount in laser processing. This involves establishing a functional relationship between the input current parameter of the liquid lens and the actual laser focal length. Based on this comparative data, the functional relationship between the defocusing amount and the input current of the liquid lens is determined to ascertain the change in defocusing amount during laser processing. Summary of the Invention

[0003] This application proposes a method and related equipment for detecting the focal length of a laser head's emitted light signal. Using this application's embodiments is beneficial for improving the accuracy of determining the focal length of the laser head's emitted light signal.

[0004] This application adopts the following technical solution.

[0005] In a first aspect, embodiments of this application provide a method for detecting the focal length of a laser head's emitted light signal. This method is applied to a laser focus measurement system, which includes an optical measurement device and an industrial control computer. The optical measurement device includes: a variable focal length element, a collimating element, a beam splitter, and a photoelectric sensor. The detection light emitted from the light source passes through the beam splitter, the variable focal length element, and the collimating element. The collimating element collimates the detection light into parallel light, which is then focused onto the surface of the workpiece by an optical converging element of the laser head or an optical converging element independent of the laser head. The light source measurement light reflected from the workpiece surface enters the optical measurement device in reverse direction via the optical converging element, and then passes through the collimating element, the variable focal length element, and the beam splitter to the photoelectric sensor.

[0006] The method includes: an industrial control computer acquiring multiple detection points formed on the surface of a workpiece by a laser head using detection light; controlling the laser head to move up and down during the formation of multiple detection points on the workpiece surface, and recording the first correspondence between the distance between the laser head and the workpiece surface when each detection point is formed and the corresponding first correspondence between each detection point; the industrial control computer acquiring multi-frame light intensity signal curves for each of the multiple detection points, wherein the multi-frame light intensity signal curves for each detection point are the light intensity signal curves reflected from the workpiece surface during the formation of each detection point; the industrial control computer determining a target detection point from the multiple detection points based on the multi-frame light intensity signal curves for each detection point, wherein the multi-frame light intensity signal curves for the target detection point satisfy preset conditions; and the industrial control computer determining the distance between the laser head and the workpiece surface when the target detection point is formed based on the first correspondence and the target detection point, and determining the distance between the laser head and the workpiece surface when the target detection point is formed as the focal length of the laser head's emitted light signal.

[0007] Among them, the multi-frame light intensity signal curve of the target detection point satisfies the preset condition, which means that the multi-frame light intensity signal curve of the target detection point is the reflected light signal corresponding to the detection light when the focal length is adjusted periodically.

[0008] It can be seen that controlling the up-and-down movement of the laser head during the formation of multiple detection points on the surface of the workpiece helps ensure the probability that the focal point of the laser head's emitted light signal is on the workpiece surface. During the control of the laser head's up-and-down movement, a first correspondence is obtained between the distance between the laser head and the workpiece surface when forming each detection point and each detection point. By acquiring the light intensity signal curve reflected from the workpiece surface during the formation of each detection point, the detection point corresponding to the light intensity signal curve reflecting from the workpiece surface that meets the preset conditions is determined as the target detection point. Based on the target detection point and the first correspondence, the distance between the laser head and the workpiece surface when forming the target detection point is determined, and this distance is determined as the focal length of the laser head's emitted light signal. This method helps improve the accuracy of the focal length of the laser head's emitted light signal.

[0009] It should be noted that when the focal point of the laser head's output signal is located on the surface of the workpiece, the distance between the laser head and the workpiece surface is the focal length of the laser head's output signal.

[0010] In one feasible implementation, the method of this embodiment further includes:

[0011] The industrial control computer adjusts the distance between the laser head and the workpiece surface to the distance between the laser head and the workpiece surface when the target detection point is formed. Then, it controls the laser head to move up and down, recording the distance of each movement to obtain multiple first defocus amounts. After each movement, the industrial control computer periodically adjusts the focal length of the variable focal length element and / or the focal length of the collimation element. During this periodic adjustment, the photoelectric sensor controls the photoelectric sensor to collect the light signal emitted by the light source through the workpiece surface at a preset frequency. The intensity of the reflected light signal is used to obtain multiple sets of sampling points, which correspond to multiple defocusing amounts. Each set of sampling points includes M1 sampling points, where M1 is an integer greater than 1. Each sampling point corresponds to a light intensity value. The industrial control computer determines the sequence number of the sampling point with the maximum light intensity value in each set of M1 sampling points, thus obtaining multiple first sequence numbers. These multiple first sequence numbers correspond to multiple first defocusing amounts. The industrial control computer determines the correspondence between the sequence number and the defocusing amount based on these multiple first sequence numbers and the multiple first defocusing amounts.

[0012] It can be seen that when the distance between the laser head and the surface of the workpiece is adjusted to form the target detection point, that is, when the focus of the laser head's output signal is adjusted to the surface of the workpiece, the laser head is moved up and down so that the output signal of the laser head is in a defocused state. After each movement, the focal length of the variable focal length element and / or collimation element is periodically adjusted. During this process, the photoelectric sensor collects the reflected light signal from the surface of the workpiece, obtaining a frame of light intensity signal curve. This light intensity signal curve consists of multiple sampling points, each corresponding to a light signal intensity. The sampling point with the highest light signal intensity in this frame of light intensity signal curve is determined. It should be understood that the defocus amount at the acquisition time corresponding to the sampling point with the highest light signal intensity is the defocus amount of the light signal emitted by the laser head. The sequence number of this sampling point among the multiple sampling points included in the light intensity signal curve is determined, and the correspondence between this sequence number and the defocus amount at the acquisition time corresponding to the sampling point with the highest light signal intensity is recorded. Since the laser head is moved multiple times, the correspondence between multiple sequence numbers and the defocus amounts at the acquisition times corresponding to multiple sampling points with the highest light signal intensity can be obtained in the above manner. Based on this correspondence, the functional relationship between the sequence number and the defocus amount is determined. By determining this functional relationship, it is convenient to subsequently determine the defocus amount of the laser head under any light signal.

[0013] In one feasible implementation, the method of this embodiment further includes: an industrial control computer acquiring multiple frames of first light intensity signal curves, each frame of which is obtained based on the photoelectric sensor periodically collecting the light signal intensity reflected by the workpiece during the process of the laser head emitting detection light to the workpiece; the industrial control computer removing light intensity signal curves with abnormal waveforms from the multiple frames of first light intensity signal curves to obtain multiple frames of second light intensity signal curves, each frame of the multiple frames of second light intensity signal curves including M2 first sampling points; the industrial control computer determining the sequence number of the second sampling point among the M2 first sampling points included in each frame of the second light intensity signal curve to obtain multiple second sequence numbers; the second sampling point is the sampling point corresponding to the maximum light intensity value among the M2 first sampling points; the industrial control computer determining multiple second defocus amounts based on the multiple second sequence numbers and the correspondence between the sequence numbers and the defocus amount, the multiple second defocus amounts corresponding to the multiple second sequence numbers; and the industrial control computer determining the defocus amount of the laser head based on the multiple second defocus amounts.

[0014] It can be seen that before determining the defocus amount based on the light intensity signal curve, removing light intensity signal curves with abnormal waveforms and determining the defocus amount using light intensity signal curves without abnormal waveforms is beneficial to improving the accuracy of the defocus amount detection results. This allows the defocus amount measured by the laser focus measurement system to be better applied to laser processing, thereby improving the quality of laser processing.

[0015] In conjunction with the first aspect, in a feasible implementation, any frame of the first light intensity signal curve Q in the multi-frame first light intensity signal curves includes M2 first sampling points, and whether the first light intensity signal curve Q is an abnormal curve is determined by the following method:

[0016] The industrial control computer determines the number of zero-crossing sampling points among the M2 first sampling points. A zero-crossing sampling point is the sampling point corresponding to the maximum or minimum light intensity value among multiple sampling points with consecutive acquisition time among the M2 first sampling points, and the light intensity value corresponding to multiple sampling points with consecutive acquisition time is neither monotonically increasing nor monotonically decreasing in time. If the number of zero-crossing sampling points among the M2 first sampling points is lower than the sampling point threshold, the industrial control computer determines that the first light intensity signal curve Q is an abnormal curve.

[0017] It can be seen that the above method can accurately determine whether the light intensity signal curve is an abnormal curve. When determining the defocus amount of the laser head based on one or more frames of the second light intensity signal curve obtained after removing the abnormal curve, it is beneficial to improve the detection accuracy of the defocus amount.

[0018] In conjunction with the first aspect, in a feasible implementation, the industrial control computer determines the number of zero-crossing sampling points among the M2 first sampling points, including:

[0019] The industrial control computer determines the light intensity value corresponding to each of the M2 first sampling points and the difference between each first sampling point and the previous first sampling point adjacent to it in terms of acquisition time; based on the differences corresponding to the M2 first sampling points, the industrial control computer determines the number of zero-crossing sampling points among the multiple first sampling points, and the zero-crossing sampling points satisfy the following condition:

[0020] The signs of the N first differences corresponding to the N first sampling points that are temporally adjacent to the zero-crossing sampling point are all first signs, and the signs of the N second differences corresponding to the N last N first sampling points that are temporally adjacent to the zero-crossing sampling point are all second signs; N is an integer greater than 1 and not greater than half the number of first sampling points;

[0021] The first symbol is the opposite of the second symbol;

[0022] The acquisition time of the zero-crossing sampling point is located in the middle of the acquisition time range of the first light intensity signal curve Q.

[0023] As can be seen, the above method can accurately determine the zero-crossing sampling point in the light intensity signal curve, which is beneficial for accurately determining whether the light intensity signal curve is an abnormal curve. Subsequently, when determining the defocus amount of the laser head based on one or more frames of the second light intensity signal curve after removing the abnormal curve, it is beneficial to improve the detection accuracy of the defocus amount.

[0024] In conjunction with the first aspect, in a feasible implementation, the maximum value of the light intensity corresponding to the sampling point in the first light intensity signal curve exceeds the light intensity threshold.

[0025] It can be seen that removing light intensity signal curves with maximum light intensity values ​​lower than the light intensity threshold before determining the defocus amount based on the light intensity signal curve is beneficial to further improve the detection accuracy of the defocus amount.

[0026] In conjunction with the first aspect, in a feasible implementation, the industrial control computer determines the defocus amount of the laser head based on multiple second defocus amounts, including:

[0027] The industrial control computer discards the larger and smaller T values ​​from the multiple second defocus values ​​to obtain one or more third defocus values; T is an integer greater than 0 and not greater than half the number of second defocus values; the industrial control computer determines the defocus value of the laser head based on one or more third defocus values.

[0028] It can be seen that by eliminating the larger and smaller values ​​among multiple second defocus values ​​to obtain one or more third defocus values, and then determining the defocus value of the laser head based on at least one or more third defocus values, it is beneficial to improve the detection accuracy of the defocus value.

[0029] In conjunction with the first aspect, in a feasible implementation, during the process of the laser head emitting detection light towards the workpiece, the focal length of the variable focal length element in the laser head changes according to a first cycle, and each first light intensity signal curve is acquired when the focal length of the variable focal length element changes for a complete cycle.

[0030] It can be seen that the first light intensity signal curve acquired during a complete cycle of focal length change of the variable focal length element is beneficial for extracting the maximum light intensity value more accurately, thereby improving the detection accuracy of defocus amount.

[0031] In conjunction with the first aspect, in a feasible implementation, the method of this embodiment further includes:

[0032] During the process of the laser head emitting detection light towards the workpiece, the industrial control computer controls the detection light emitted by the laser head to traverse multiple measurement points on the workpiece according to the second cycle; wherein, the second cycle is shorter than the first cycle.

[0033] It can be seen that by detecting the light traversing multiple measurement points, the light intensity value of the first light intensity signal curve can cover the differences in light intensity values ​​caused by differences in material roughness, which is beneficial to improving the tolerance for differences in material surface roughness and improving the detection accuracy of defocusing.

[0034] In conjunction with the first aspect, in a feasible implementation, the method of this embodiment includes:

[0035] The industrial control computer selects a point on the surface of the workpiece as the first measurement point; multiple second measurement points are determined around the first measurement point, and the distance between each second measurement point and the first measurement point is less than a first preset distance. The multiple measurement points include the first measurement point and multiple second measurement points.

[0036] In this way, the detection light can quickly traverse the first and second measurement points, so that each first light intensity signal curve can cover the information of the first and second measurement points, which is beneficial to improving the detection accuracy of the defocus amount.

[0037] In conjunction with the first aspect, in a feasible implementation, multiple second measurement points are distributed in a matrix or ring around the first measurement point, or in a spiral distribution starting from the first measurement point.

[0038] The above methods can improve the coverage of the detection spot, increase the efficiency of the detection light traversing the measurement points, and enable each first light intensity signal curve to cover more material surface roughness differences, which is beneficial to improving the detection accuracy of defocusing.

[0039] Secondly, embodiments of this application provide an industrial control computer, including a control unit, a recording unit, an acquisition unit, a processing unit, and a determination unit. The control unit, recording unit, acquisition unit, processing unit, and determination unit are used to implement the method provided in any one of the first aspects.

[0040] Thirdly, embodiments of this application provide an electronic device, including: a processor connected to a memory for storing a computer program, and the processor for executing the computer program stored in the memory to cause the industrial control computer to perform the method provided in any of the first aspects.

[0041] Fourthly, embodiments of this application provide a laser welding control system, including a laser welding system, a multi-optical sensor module, a signal processing module, and an industrial control computer, wherein the industrial control computer is used to execute the method provided in any of the first aspects.

[0042] Fifthly, embodiments of this application provide a computer-readable storage medium storing a computer program that causes a computer to perform the methods provided in any of the first aspects.

[0043] In a sixth aspect, embodiments of this application provide a computer program product, the computer program product including a computer program / instructions, which, when executed, implement the method as described in any one of the first aspects.

[0044] It is understood that the industrial control computer described in the second and third aspects, the laser welding control system described in the fourth aspect, the computer-readable storage medium described in the fifth aspect, or the computer program product described in the sixth aspect are all used to implement the method provided in any one of the first aspects. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A schematic diagram of a laser focus measurement system provided in an embodiment of this application;

[0047] Figure 2a A schematic flowchart illustrating a method for detecting the focal length of a laser head's emitted light signal, provided in an embodiment of this application;

[0048] Figure 2b A flowchart illustrating a method for determining defocus amount provided in an embodiment of this application;

[0049] Figure 3 This is a schematic diagram of a measuring point on a machined part provided in an embodiment of this application;

[0050] Figure 4 This illustrates the first frame of light intensity signal collected by the photoelectric sensor;

[0051] Figure 5 The diagram illustrates the multiple frames of first light intensity signals collected by the photoelectric sensor;

[0052] Figure 6 The normal and abnormal waveforms are shown.

[0053] Figure 7 This is a schematic diagram of the structure of an industrial control computer provided in an embodiment of this application;

[0054] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms "a," "the," and "the" used in the embodiments, descriptions, and claims of this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should be understood that the term "and / or" used herein is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects are in an "or" relationship. It should be understood that although the terms "first," "second," and similar words may be used in the embodiments of this application, they do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," and similar words do not indicate a quantity limitation, but rather indicate the existence of at least one. "A plurality" in the embodiments of this application refers to two or more.

[0057] See Figure 1 , Figure 1 This is a schematic diagram of a laser focus measurement system provided in an embodiment of this application. Figure 1 As shown, the system includes an optical measuring device 102 and an industrial control computer 108.

[0058] The optical measuring device 102 includes a collimating lens 103, a variable focal length element 104, a beam splitter 105, a light source 106, and a photoelectric sensor 107. In one example, the light source 106 is located inside the optical measuring device 102. In another example, the light source 106 is located outside the optical measuring device 102.

[0059] During measurement, the laser head 101 is aligned with the workpiece. The detection light emitted by the light source 106 enters the laser head 101 through the beam splitter 105, the liquid lens 104, and the collimating lens 103 and illuminates the workpiece. The light reflected from the workpiece passes through the laser head 101, the collimating lens 103, the liquid lens 104, and the beam splitter 105, and finally reaches the photoelectric sensor 107. The photoelectric sensor 107 is used to collect the detection light signal reflected from the workpiece and outputs the light intensity value.

[0060] In one example, the variable focal length element 104 is a liquid lens.

[0061] The applicant discovered that in some processing scenarios, such as workpiece tilting, workpiece deformation, workpiece surface contamination, galvanometer oscillation error, and measurement system communication error, the light intensity signal collected by the laser focus measurement system will vary. The defocus amount calculated using the varied light intensity signal cannot reflect the true defocus amount.

[0062] To improve the accuracy of defocus detection, this application proposes the following specific implementation method.

[0063] See Figure 2a , Figure 2a This is a schematic flowchart illustrating a method for detecting the focal length of a laser head's emitted light signal, provided in an embodiment of this application. Figure 2a As shown, the method includes:

[0064] S201a. The industrial control computer acquires multiple detection points formed on the surface of the workpiece by the laser head using detection light. During the process of forming multiple detection points on the surface of the workpiece, the laser head is controlled to move up and down, and the relationship between the distance between the laser head and the surface of the workpiece when each detection point is formed and the corresponding relationship between each detection point is recorded.

[0065] Specifically, to determine the focal length of the laser head's emitted signal, the industrial control computer uses the laser head to create multiple detection points on the workpiece surface using detection light. During the creation of these detection points, the computer controls the laser head to move up and down to adjust the distance between it and the workpiece surface. The industrial control computer records the distance between the laser head and the workpiece surface at each of the multiple detection points, thus recording the correspondence between the distance between the laser head and the workpiece surface and each detection point.

[0066] S202a, The industrial control computer acquires the multi-frame light intensity signal curve of each of the multiple detection points. The multi-frame light intensity signal curve of each detection point is the light intensity signal curve reflected from the surface of the workpiece during the formation of each detection point. Based on the multi-frame light intensity signal curve of each detection point, a target detection point is determined from the multiple detection points. The multi-frame light intensity signal curve of the target detection point meets the preset conditions. Based on the first correspondence and the target detection point, the distance between the laser head and the surface of the workpiece when the target detection point is formed is determined. The distance between the laser head and the surface of the workpiece when the target detection point is formed is determined as the focal length of the light output signal of the laser head.

[0067] It should be understood that the multi-frame light intensity signal curve of the target detection point satisfies the preset conditions, meaning that the multi-frame light intensity signal curve of the target detection point is the reflected light signal corresponding to the detection light when the focus is adjusted periodically.

[0068] For the reasons mentioned above, the industrial control computer acquires images of multiple detection points on the surface of the workpiece, then determines the area occupied by each detection point in the image, and identifies the detection point with the smallest area as the minimum detection point. After determining the minimum detection point, the distance between the laser head and the workpiece surface corresponding to the minimum detection point is determined based on the correspondence between the distance between the laser head and the workpiece surface and each detection point. This distance is then defined as the focal length of the laser head's emitted light signal.

[0069] In one feasible implementation, the industrial control computer adjusts the distance between the laser head and the workpiece surface to the distance between the laser head and the workpiece surface when the target detection point is formed. Then, it controls the laser head to move up and down, recording the distance of each movement to obtain multiple first defocus amounts. After each movement, the industrial control computer periodically adjusts the focal length of the variable focal length element and / or the focal length of the collimating element. During the periodic adjustment of the focal length of the variable focal length element and / or the collimating element, it controls the photoelectric sensor to collect the light emitted by the light source at a preset frequency. The intensity of the light signal reflected from the surface of the processed part is used to obtain multiple sets of sampling points. These multiple sets of sampling points correspond to multiple defocusing amounts. Each set of sampling points includes M sampling points, where M is an integer greater than 1. Each sampling point corresponds to a light intensity value. The industrial control computer determines the sequence number of the sampling point corresponding to the maximum light intensity value in each set of M sampling points, thus obtaining multiple first sequence numbers. These multiple first sequence numbers correspond to multiple first defocusing amounts. The industrial control computer determines the correspondence between the sequence number and the defocusing amount based on the multiple first sequence numbers and the multiple first defocusing amounts.

[0070] Specifically, after obtaining the focal length of the laser head's emitted light signal, the distance between the laser head and the workpiece surface is adjusted to the focal length of the laser head's emitted light signal. That is, when the focal point of the laser head's emitted light signal is adjusted to the workpiece surface, the laser head is moved up and down to bring the emitted light signal into a defocused state, including positive defocus, negative defocus, and zero defocus. After each movement, the focal length of the variable focal length element and / or collimation element is periodically adjusted. During this process, the photoelectric sensor collects the reflected light signal from the workpiece surface, obtaining a frame of light intensity signal curve. This light intensity signal curve consists of M1 sampling points, each corresponding to a light signal intensity, where M1 is an integer greater than 1. For example, the photoelectric sensor collects the light signal intensity at a preset frequency for a preset duration to obtain M1 sampling points, each corresponding to a light intensity value. The industrial control computer determines the sampling point with the highest light signal intensity in the light intensity signal curve for that frame. It should be understood that since the energy on the workpiece surface is at its maximum at the acquisition time corresponding to the sampling point with the highest light signal intensity, the defocus amount at the acquisition time corresponding to the sampling point with the highest light signal intensity is the first defocus amount of the laser head's emitted light signal. The industrial control computer determines the first sequence number of this sampling point among the M1 sampling points contained in the light intensity signal curve and records the correspondence between this first sequence number and the first defocus amount at the acquisition time corresponding to the sampling point with the highest light signal intensity. It should be noted that this sequence number can be the sequence number of the M1 sampling points acquired in time.

[0071] Since the laser head is moved multiple times, the correspondence between the first defocus amount at the sampling time corresponding to the sampling points with the maximum optical signal intensity can be obtained in the above manner. Based on the correspondence between the first sequence number and the first defocus amount, the functional relationship (i.e., the correspondence) between the sequence number and the defocus amount is determined. By determining this functional relationship, it is convenient to determine the defocus amount of the laser head under any optical signal.

[0072] The following describes a method for determining the defocus amount of a laser head using the correspondence between serial numbers and defocus amounts. Figure 2b As shown:

[0073] S201b: The industrial control computer acquires multiple frames of the first light intensity signal curve. Each frame of the multiple frames of the first light intensity signal curve is obtained based on the intensity of the light signal reflected by the workpiece periodically collected by the photoelectric sensor during the process of the laser head emitting detection light to the workpiece.

[0074] It can be understood that the multi-frame first light intensity signal curve can be a set of discrete light intensity signals; or it can be a smooth curve obtained by fitting a set of light intensity signals. The first light intensity signal curve of each frame is acquired when the focal length of the variable focal length element changes for one or more complete cycles. Since the laser periodically changes the input current of the liquid lens from small to large at a certain defocus amount, the system can acquire the reflected light intensity at the corresponding input current. When the reflected light intensity reaches its maximum value, a set of comparative data is formed between the input current of the liquid lens and the focal length.

[0075] In one feasible implementation, during the process of the laser head emitting detection light towards the workpiece, the focal length of the variable focal length element in the laser head changes according to the first cycle, and the first light intensity signal curve of each frame is acquired when the focal length of the variable focal length element changes for one complete cycle.

[0076] In one feasible implementation, the method of this embodiment further includes:

[0077] During the process of the laser head emitting detection light towards the workpiece, the industrial control computer controls the detection light emitted by the laser head to traverse multiple measurement points on the workpiece according to the second cycle; wherein, the second cycle is shorter than the first cycle.

[0078] Specifically, after receiving the start signal, the industrial control computer controls the laser focus measurement system to emit detection light towards the workpiece, and the emitted detection light traverses multiple measurement points on the workpiece according to a second cycle. These multiple measurement points include a first measurement point and multiple second measurement points. In one example, such as... Figure 3As shown, multiple second measurement points are distributed in a matrix, a ring, or a spiral pattern with the first measurement point as the center. During the process of the laser head emitting detection light towards the workpiece, the industrial control computer controls the focal length of the variable focal length element in the laser head to change according to the first cycle.

[0079] During the process of the laser head emitting detection light towards the workpiece, the photoelectric sensor collects the detection light signal reflected by the workpiece and outputs the light intensity value. Figure 4 This illustrates one frame of the first light intensity signal captured by the photoelectric sensor. The light intensity sensor will output multiple frames of the first light intensity signal. Figure 5 The diagram illustrates multiple frames of first light intensity signals acquired by a photoelectric sensor. Each frame represents the light intensity signal acquired by the photoelectric sensor during one cycle of the focal length change of the variable focal length element, and the duration of each frame does not exceed the focal length change cycle of the variable focal length element. It should be understood that... Figure 4 The light intensity signal curve shown is composed of multiple sampling points. Figure 4 The horizontal axis X in the figure represents Figure 4 The number of the sampling point in a frame of light intensity signal curve shown. Figure 5 The first light intensity signal curve shown in each frame consists of multiple sampling points. Figure 5 The horizontal axis X in the figure represents Figure 5 The sequence number of the sampling point in the curve after the first light intensity absorption of each frame is shown.

[0080] In one feasible implementation, the method of this embodiment further includes:

[0081] The industrial control computer selects a point on the surface of the workpiece as the first measurement point; the industrial control computer determines multiple second measurement points around the first measurement point, and the distance between each second measurement point and the first measurement point is less than a first preset distance. The multiple measurement points include the first measurement point and multiple second measurement points.

[0082] S202b: The industrial control computer removes light intensity signal curves with abnormal waveforms from the multi-frame first light intensity signal curves to obtain multi-frame second light intensity signal curves.

[0083] In one feasible implementation, any frame of the first light intensity signal curve Q in the multi-frame first light intensity signal curves includes M2 first sampling points. The industrial control computer removes light intensity signal curves with abnormal waveforms from the multi-frame first light intensity signal curves to obtain the multi-frame second light intensity signal curves, including:

[0084] The industrial control computer determines the number of zero-crossing sampling points among the M2 first sampling points. A zero-crossing sampling point is the sampling point corresponding to the maximum or minimum light intensity value among multiple sampling points with consecutive acquisition time among the M2 first sampling points, and the light intensity value corresponding to multiple sampling points with consecutive acquisition time is neither monotonically increasing nor monotonically decreasing in time. If the number of zero-crossing sampling points among the M2 first sampling points is lower than the sampling point threshold, the industrial control computer determines that the first light intensity signal curve Q is an abnormal curve.

[0085] It should be noted that the first light intensity signal curve is not a straight line, but a curve containing one or more peaks and one or more troughs. The zero-crossing sampling points of the first light intensity signal curve include the sampling points corresponding to the peaks and the sampling points corresponding to the troughs in the first light intensity signal curve.

[0086] In a specific example, the industrial control computer determines the light intensity value corresponding to each of the M2 first sampling points and the difference between each first sampling point and the previous first sampling point adjacent to it in terms of acquisition time; based on the differences corresponding to the M2 first sampling points, the industrial control computer determines the number of zero-crossing sampling points among the multiple first sampling points, and the zero-crossing sampling points satisfy the following condition:

[0087] The signs of the N first differences corresponding to the N first sampling points adjacent to the zero-crossing sampling point in terms of acquisition time are all the first signs, and the signs of the N second differences corresponding to the N last N first sampling points adjacent to the zero-crossing sampling point in terms of acquisition time are all the second signs; N is an integer greater than 1 and less than M2;

[0088] The first symbol is the opposite of the second symbol;

[0089] The acquisition time of the zero-crossing sampling point is located in the middle of the acquisition time range of the first light intensity signal curve Q.

[0090] Specifically, the following method is used to determine whether the first light intensity signal curves of multiple frames are abnormal waveforms:

[0091] Any frame of the first light intensity signal curve Q in the multi-frame first light intensity signal curve includes M2 first sampling points, each corresponding to a light intensity value; the industrial control computer calculates the difference between the light intensity value corresponding to each first sampling point and the light intensity value corresponding to the previous first sampling point adjacent to that first sampling point, i.e., the difference corresponding to each first sampling point; the method for determining whether each first sampling point is a zero-crossing sampling point includes: the industrial control computer determines the signs of the N first differences corresponding to the N first sampling points adjacent to any first sampling point P in the M2 first sampling points in terms of acquisition time, and determines the signs of the N second differences corresponding to the N last first sampling points adjacent to the first sampling point P in terms of acquisition time. If the signs of the N first differences are all first signs, and the signs of the N second differences are second signs, and the acquisition time of the first sampling point P is located in the middle time range of the acquisition time range corresponding to the first light intensity signal curve Q, then the industrial control computer determines that the first sampling point P is a zero-crossing sampling point.

[0092] In this system, the first sign is either positive or negative, the second sign is either positive or negative, and the first sign is the opposite of the second sign. In one example, the first sign is positive and the second sign is negative; in another example, the first sign is negative and the second sign is positive.

[0093] The difference between the start time of the middle time range of the acquisition time range of the first light intensity signal curve Q and the start time of the acquisition time range of the first light intensity signal curve Q is the same as the difference between the end time of the acquisition time range of the first light intensity signal curve Q and the end time of the middle time range, and this difference is greater than the difference threshold. For example, the acquisition time range of the first light intensity signal curve Q is [100s-200s], and the middle time range is [110s-190s].

[0094] In a specific example, the light intensity values ​​corresponding to the first four first sampling points adjacent to the first sampling point P are 5 cd, 10 cd, 20 cd, and 30 cd, respectively; the light intensity value corresponding to the first sampling point P is 40 cd; and the light intensity values ​​corresponding to the last three first sampling points adjacent to the first sampling point P are 35 cd, 25 cd, and 10 cd, respectively. The acquisition time range of the first light intensity signal curve Q is [100s-200s], and the acquisition time of the first sampling point P is 151s. Therefore, the differences between the first three first sampling points adjacent to the first sampling point P are 5 cd, 10 cd, and 10 cd, respectively, and the differences between the last three first sampling points adjacent to the first sampling point P are -5 cd, -10 cd, and -15 cd, respectively. The signs of the differences corresponding to the first three first sampling points adjacent to the first sampling point P are all positive, and the signs of the differences corresponding to the last three first sampling points adjacent to the first sampling point P are all negative. Furthermore, the acquisition time of the first sampling point P is within the middle time range of the acquisition time range of the first light intensity signal curve Q. Therefore, it can be determined that the first sampling point P is a zero-crossing sampling point.

[0095] In one feasible implementation, the maximum value of the light intensity corresponding to the sampling point in the first light intensity signal curve exceeds the light intensity threshold. That is, before performing zero-crossing detection, the industrial control computer determines whether the maximum value of the light intensity corresponding to the sampling point on the first light intensity signal curve Q exceeds the light intensity threshold. If it does, the industrial control computer then determines whether the first light intensity signal curve Q is an abnormal waveform; if it does not exceed the threshold, the industrial control computer removes the first light intensity signal curve Q from the above multiple first light intensity signal curves and no longer participates in the subsequent defocus calculation process. Figure 6 The diagram illustrates the normal and abnormal waveforms.

[0096] S203b, the industrial control computer determines the sequence number of the second sampling point among the M2 first sampling points included in each frame of the second light intensity signal curve, so as to obtain multiple second sequence numbers; the second sampling point is the sampling point corresponding to the maximum light intensity value among the M2 first sampling points; the industrial control computer determines multiple second defocus amounts based on the multiple second sequence numbers and the correspondence between the sequence numbers and the defocus amount, and the multiple second defocus amounts correspond to the multiple second sequence numbers.

[0097] S204b: The industrial control computer determines the defocus amount of the laser head based on multiple second defocus amounts.

[0098] In one feasible implementation, the industrial control computer discards the larger T and smaller T from a plurality of second defocus quantities to obtain one or more third defocus quantities; T is an integer greater than 0 and not greater than half the number of second defocus quantities; the industrial control computer determines the defocus quantity of the laser head based on one or more third defocus quantities.

[0099] Specifically, the industrial control computer discards the larger and smaller T values ​​from multiple second defocus values ​​to obtain one or more third defocus values. When there are multiple third defocus values, the industrial control computer determines the average or median value of the multiple third defocus values ​​as the defocus value of the laser head. When there is only one third defocus value, the industrial control computer uses that third defocus value as the defocus value of the laser head.

[0100] In one feasible implementation, when the industrial control computer obtains only one second light intensity signal curve according to the operation of S202b, the industrial control computer determines the sequence number of the sampling point corresponding to the maximum light intensity value in the second light intensity signal curve among the M sampling points contained in the second light intensity signal curve, and determines the defocus amount corresponding to the sequence number based on the sequence number and the correspondence between the sequence number and the defocus amount, which is the defocus amount of the laser head.

[0101] It should be noted that the determination of whether the maximum value of the light intensity corresponding to the sampling point in the light intensity signal curve exceeds the light intensity threshold can be performed before or after detecting whether the light intensity signal curve is an abnormal waveform curve.

[0102] As can be seen from the scheme of this application, controlling the up-and-down movement of the laser head during the formation of multiple detection points on the workpiece helps ensure the probability that the focal point of the laser head's emitted light signal is on the surface of the workpiece. Determining the distance corresponding to the smallest detection point as the focal length of the laser head's emitted light signal improves the accuracy of the focal length. Before determining the defocus amount based on the light intensity signal curve, removing light intensity signal curves with abnormal waveforms and determining the defocus amount using light intensity signal curves without abnormal waveforms improves the detection accuracy of the defocus amount, thus allowing the defocus amount measured by the laser focus measurement system to be better applied to laser processing and improve the quality of laser processing. Furthermore, removing light intensity signal curves with maximum light intensity values ​​lower than the light intensity threshold before determining the defocus amount further improves the detection accuracy of the defocus amount.

[0103] See Figure 7 , Figure 7 This is a schematic diagram of the structure of an industrial control computer provided in an embodiment of this application. The industrial control computer 700 is... Figure 1The industrial control computer 108 of the laser focus measurement system also includes an optical measurement device, which includes a variable focal length element, a collimating element, a beam splitter, and a photoelectric sensor. The detection light emitted by the light source passes through the beam splitter, the variable focal length element, and the collimating element. The collimating element collimates the detection light into parallel light, which is then focused onto the surface of the workpiece by the optical converging element of the laser head or an optical converging element independent of the laser head. The light source measurement light reflected from the surface of the workpiece enters the optical measurement device in reverse through the optical converging element, and then passes through the collimating element, the variable focal length element, and the beam splitter to the photoelectric sensor.

[0104] like Figure 7 As shown, the industrial control computer 700 includes:

[0105] Acquisition unit 701 is used to acquire multiple detection points formed on the surface of the workpiece by the laser head using detection light.

[0106] The control unit 702 controls the up-and-down movement of the laser head during the process of forming multiple detection points on the surface of the workpiece;

[0107] Recording unit 703 is used to record the distance between the laser head and the surface of the workpiece when each detection point is formed and the first correspondence between each detection point;

[0108] The acquisition unit 701 is also used to acquire the multi-frame light intensity signal curve of each of the multiple detection points. The multi-frame light intensity signal curve of each detection point is the light intensity signal curve reflected by the surface of the workpiece during the formation of each detection point.

[0109] The determining unit 704 is used to determine the target detection point from multiple detection points based on the multi-frame light intensity signal curve of each detection point, and the multi-frame light intensity signal curve of the target detection point meets the preset conditions; the industrial control computer determines the distance between the laser head and the surface of the workpiece when the target detection point is formed based on the first correspondence and the target detection point, and determines the distance between the laser head and the surface of the workpiece when the target detection point is formed as the focal length of the light output signal of the laser head.

[0110] Among them, the multi-frame light intensity signal curve of the target detection point satisfies the preset condition, which means that the multi-frame light intensity signal curve of the target detection point is the reflected light signal corresponding to the detection light when the focal length is adjusted periodically.

[0111] In one feasible implementation, the control unit 702 is further configured to adjust the distance between the laser head and the workpiece surface to the distance between the laser head and the workpiece surface when the target detection point is formed, and then control the laser head to move up and down;

[0112] The recording unit 703 is also used to record the distance of each movement in order to obtain multiple first defocus amounts;

[0113] The control unit 702 is further configured to periodically adjust the focal length of the variable focal length element and / or the focal length of the collimating element after each movement. During the periodic adjustment of the focal length of the variable focal length element and / or the focal length of the collimating element, the control unit controls the photoelectric sensor to collect the intensity of the light signal reflected from the surface of the workpiece by the light signal emitted by the light source at a preset frequency, so as to obtain multiple sets of sampling points. The multiple sets of sampling points correspond to multiple defocus amounts. Each set of sampling points includes M1 sampling points; M1 is an integer greater than 1; each sampling point corresponds to a light intensity value.

[0114] The determining unit 704 is further configured to determine the sequence number of the sampling point corresponding to the maximum light intensity value in each of the M1 sampling points in each group, so as to obtain multiple first sequence numbers; the multiple first sequence numbers correspond to multiple first defocus amounts; and determine the correspondence between the sequence number and the defocus amount based on the multiple first sequence numbers and the multiple first defocus amounts.

[0115] In one feasible implementation, the industrial control computer 700 also includes:

[0116] The acquisition unit 701 is used to acquire multiple frames of first light intensity signal curves, which are obtained based on periodically acquiring the light signals reflected by the workpiece during the process of the laser head emitting detection light to the workpiece;

[0117] The processing unit 705 is used to remove light intensity signal curves with abnormal waveforms from the multi-frame first light intensity signal curves to obtain multi-frame second light intensity signal curves; each frame of the multi-frame second light intensity signal curves includes M2 first sampling points.

[0118] The determining unit 704 is used to determine the sequence number of the second sampling point among the M2 first sampling points included in each frame of the second light intensity signal curve, so as to obtain multiple second sequence numbers; the second sampling point is the sampling point corresponding to the maximum light intensity value among the M2 first sampling points; the industrial control computer determines multiple second defocus amounts based on the multiple second sequence numbers and the correspondence between the sequence numbers and the defocus amount, and the multiple second defocus amounts correspond to the multiple second sequence numbers; the defocus amount of the laser head is determined based on the multiple second defocus amounts.

[0119] In one feasible implementation, any frame of the first light intensity signal curve Q in the multi-frame first light intensity signal curves includes M first sampling points, and whether the first light intensity signal curve Q is an abnormal curve is determined by the following method:

[0120] The determining unit 704 is used to determine the number of zero-crossing sampling points among the M2 first sampling points; wherein, the zero-crossing sampling point is the sampling point corresponding to the maximum or minimum light intensity value among multiple sampling points with consecutive acquisition time among the M first sampling points, and the light intensity value corresponding to the multiple sampling points with consecutive acquisition time is neither monotonically increasing nor monotonically decreasing in time; if the number of zero-crossing sampling points among the M2 first sampling points is lower than the sampling point threshold, the industrial control computer determines that the first light intensity signal curve Q is an abnormal curve.

[0121] In one feasible implementation, the determining unit 704 is specifically used to determine the number of zero-crossing sampling points among the M2 first sampling points:

[0122] Determine the light intensity value corresponding to each of the M first sampling points and the difference between each first sampling point and the previous first sampling point adjacent to it in terms of acquisition time; the industrial control computer determines the number of zero-crossing sampling points among the M2 first sampling points based on the differences corresponding to the M2 first sampling points; wherein, the zero-crossing sampling points satisfy the following condition:

[0123] The signs of the N first differences corresponding to the N first sampling points that are temporally adjacent to the zero-crossing sampling point are all first signs, and the signs of the N second differences corresponding to the N last N first sampling points that are temporally adjacent to the zero-crossing sampling point are all second signs; N is an integer greater than 1 and not greater than half the number of first sampling points;

[0124] The first symbol is the opposite of the second symbol;

[0125] The acquisition time of the zero-crossing sampling point is located in the middle of the acquisition time range of the first light intensity signal curve Q.

[0126] In one feasible implementation, the maximum value of the light intensity corresponding to the sampling point in the first light intensity signal curve exceeds the light intensity threshold.

[0127] In one feasible implementation, in determining the defocus amount of the laser head based on multiple second defocus amounts, the determining unit 704 is specifically used for:

[0128] The larger and smaller T values ​​among the multiple second defocus values ​​are discarded to obtain one or more third defocus values; T is an integer greater than 0 and not greater than half the number of second defocus values; the defocus value of the laser head is determined based on one or more third defocus values.

[0129] In one feasible implementation, during the process of the laser head emitting detection light towards the workpiece, the focal length of the variable focal length element in the laser head changes according to a first cycle, and each first light intensity signal curve is acquired when the focal length of the variable focal length element changes for a complete cycle.

[0130] In one feasible implementation, the processing unit 705 is further configured to:

[0131] During the process of the laser head emitting detection light towards the workpiece, the detection light emitted by the laser head is controlled to traverse multiple measurement points on the workpiece according to a second cycle; wherein, the second cycle is shorter than the first cycle.

[0132] In one feasible implementation, the processing unit 705 is further configured to:

[0133] A point is selected on the surface of the workpiece as the first measurement point; multiple second measurement points are determined around the first measurement point, and the distance between each second measurement point and the first measurement point is less than a first preset distance. The multiple measurement points include the first measurement point and multiple second measurement points.

[0134] In one feasible implementation, multiple second measurement points are distributed in a matrix or ring around the first measurement point, or in a spiral distribution starting from the first measurement point.

[0135] It should be noted that the aforementioned units (acquisition unit 701, control unit 702, recording unit 703, determination unit 704, and processing unit 705) are used to execute the relevant steps of the laser head light output signal focal length detection method described above. The various units or modules in the industrial control computer 700 can be individually or entirely merged into one or more other units or modules, or some of these units or modules can be further divided into multiple functionally smaller units or modules. This achieves the same operation without affecting the technical effects of the embodiments of the present invention. The aforementioned units or modules are based on logical function division. In practical applications, the function of one unit (or module) can also be implemented by multiple units (or modules), or the function of multiple units (or modules) can be implemented by one unit (or module).

[0136] Based on the description of the above method and device embodiments, please refer to... Figure 8 The present invention also provides a schematic diagram of the structure of an electronic device 800. Figure 8 The electronic device 800 shown (specifically, it can be a computer device) includes a memory 801, a processor 802, a communication interface 803, and a bus 804. The memory 801, processor 802, and communication interface 803 are interconnected via the bus 804.

[0137] The memory 801 can be a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM).

[0138] The memory 801 can store a program. When the program stored in the memory 801 is executed by the processor 802, the processor 802 and the communication interface 803 are used to execute the various steps of the laser head light output signal focal length detection method of the present application embodiment.

[0139] The processor 802 may be a general-purpose central processing unit (CPU), microprocessor, application specific integrated circuit (ASIC), graphics processing unit (GPU), or one or more integrated circuits, used to execute relevant programs to achieve the functions required by the units in the electronic device 800 of this application embodiment, or to execute the laser head light output signal focal length detection method of this application method embodiment.

[0140] The processor 802 can also be an integrated circuit chip with signal processing capabilities. In implementation, each step of the laser head output signal focal length detection method of this application can be completed by the integrated logic circuits in the hardware of the processor 802 or by software instructions. The aforementioned processor 802 can also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory 801. The processor 802 reads the information in the memory 801 and, in conjunction with its hardware, performs the functions required by the units included in the industrial control computer 700 of this application embodiment, or performs the laser head light emission signal focal length detection method of this application method embodiment.

[0141] The communication interface 803 uses transceiver devices, such as, but not limited to, transceivers, to enable communication between the electronic device 800 and other devices or communication networks. For example, data can be acquired through the communication interface 803.

[0142] Bus 804 may include a pathway for transmitting information between various components of electronic device 800 (e.g., memory 801, processor 802, communication interface 803).

[0143] It should be noted that, although Figure 8 The illustrated electronic device 800 only shows the memory, processor, and communication interface. However, those skilled in the art should understand that in specific implementations, the electronic device 800 may also include other devices necessary for normal operation. Furthermore, depending on specific needs, those skilled in the art should understand that the electronic device 800 may also include hardware devices for implementing other additional functions. Moreover, those skilled in the art should understand that the electronic device 800 may only include the devices necessary for implementing the embodiments of this application, and may not necessarily include... Figure 8 All the devices shown.

[0144] This application embodiment also provides a chip, which includes a processor and a data interface. The processor reads instructions stored in the memory through the data interface to implement the laser head light output signal focal length detection method.

[0145] Optionally, as one implementation, the chip may further include a memory storing instructions, and the processor is used to execute the instructions stored in the memory. When the instructions are executed, the processor is used to execute the laser head light output signal focal length detection method.

[0146] This application also provides a computer-readable storage medium storing instructions that, when executed on a computer or processor, cause the computer or processor to perform one or more steps of any of the above methods.

[0147] This application also provides a computer program product containing instructions. When the computer program product is run on a computer or processor, it causes the computer or processor to perform one or more steps of any of the methods described above.

[0148] Those skilled in the art will appreciate that the functionality described in conjunction with the various illustrative logic blocks, modules, and algorithmic steps disclosed herein can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality described by the various illustrative logic blocks, modules, and steps can be stored or transmitted as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may comprise a computer-readable storage medium, which corresponds to a tangible medium, such as a data storage medium, or a communication medium that includes any medium facilitating the transfer of a computer program from one place to another (e.g., based on a communication protocol). In this way, the computer-readable medium may substantially correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium, such as a signal or carrier wave. The data storage medium may be any available medium accessible by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementing the techniques described in this application. A computer program product may comprise a computer-readable medium.

[0149] By way of example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or any other media that can be used to store desired program code in the form of instructions or data structures and is accessible by a computer. Furthermore, any connection is properly referred to as computer-readable media. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. However, it should be understood that the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other temporary media, but are specifically addressed to non-temporary tangible storage media. As used herein, disks and optical discs include compact optical discs (CDs), laser optical discs, optical discs, digital versatile optical discs (DVDs), and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs reproduce data optically using lasers. The combination of the above items should also be included in the scope of computer-readable media.

[0150] Instructions can be executed by one or more processors, such as digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used herein can refer to any of the foregoing structures or any other structures suitable for implementing the techniques described herein. Furthermore, in some aspects, the functionality described in the various illustrative logic blocks, modules, and steps described herein can be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into combined codecs. Moreover, the techniques can be fully implemented within one or more circuit or logic elements.

[0151] The technology of this application can be implemented in a wide variety of devices or apparatuses, including wireless handheld devices, integrated circuits (ICs), or a set of ICs (e.g., chipsets). The various components, modules, or units described in this application are intended to emphasize functional aspects of the apparatus for performing the disclosed technology, but do not necessarily need to be implemented by different hardware units. In fact, as described above, the various units can be combined with suitable software and / or firmware within coded hardware units, or provided via interoperable hardware units (containing one or more processors as described above).

[0152] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the specific descriptions of the corresponding steps in the foregoing method embodiments, and will not be repeated here.

[0153] It should be understood that in the description of this application, unless otherwise stated, " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B can represent A or B; where A and B can be singular or plural. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. Additionally, to facilitate a clear description of the technical solutions of the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" do not necessarily imply difference. In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0154] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the division of units is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The coupling, direct coupling, or communication connection shown or discussed between each other may be indirect coupling or communication connection through some interfaces, apparatuses, or units, and may be electrical, mechanical, or other forms.

[0155] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0156] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions. When these computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be read-only memory (ROM), random access memory (RAM), or magnetic media, such as floppy disks, hard disks, magnetic tapes, magnetic disks, or optical media, such as digital versatile discs (DVDs), or semiconductor media, such as solid state disks (SSDs).

[0157] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

[0158] The device embodiments described above are merely illustrative. The units and modules described as separate components may or may not be physically separate. Furthermore, some or all of the units and modules can be selected to achieve the purpose of this embodiment, depending on actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0159] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for detecting the focal length of a laser head's emitted light signal, characterized in that, The method is applied to a laser focus measurement system, which includes optical measurement equipment and an industrial control computer. The optical measurement equipment includes: a variable focal length element, a collimating element, a beam splitter, and a photoelectric sensor. The detection light emitted from the light source passes through the beam splitter, the variable focal length element, and the collimating element; wherein, the collimating element collimates the detection light into parallel light, and the parallel light is focused onto the surface of the workpiece by the optical converging element of the laser head or an optical converging element independent of the laser head; the light source measurement light reflected from the surface of the workpiece enters the optical measurement device in reverse through the optical converging element, and then passes through the collimating element, the variable focal length element, and the beam splitter to the photoelectric sensor. The method includes: The laser head is used to obtain multiple detection points formed on the surface of the workpiece by the detection light. During the process of forming the multiple detection points on the surface of the workpiece, the laser head is controlled to move up and down, and a first correspondence between the distance between the laser head and the surface of the workpiece when each detection point is formed and each detection point is recorded. Acquire multi-frame light intensity signal curves for each of the plurality of detection points, wherein the multi-frame light intensity signal curves for each detection point are light intensity signal curves reflected from the surface of the workpiece during the formation of each detection point; The target detection point is determined from the multiple detection points based on the multi-frame light intensity signal curve of each detection point, and the multi-frame light intensity signal curve of the target detection point satisfies the preset conditions; the multi-frame light intensity signal curve of the target detection point is the reflected light signal corresponding to the detection light when the focus is adjusted periodically. Based on the first correspondence and the target detection point, the distance between the laser head and the surface of the workpiece when the target detection point is formed is determined, and the distance between the laser head and the surface of the workpiece when the target detection point is formed is determined as the focal length of the laser head's emitted light signal.

2. The method according to claim 1, characterized in that, The method further includes: The distance between the laser head and the surface of the workpiece is adjusted to the distance between the laser head and the surface of the workpiece when the target detection point is formed. Then, the laser head is controlled to move up and down, and the distance of each movement is recorded to obtain multiple first defocus amounts. After each movement, the focal length of the variable focal length element and / or the focal length of the collimating element are periodically adjusted. During the periodic adjustment of the focal length of the variable focal length element and / or the focal length of the collimating element, the photoelectric sensor is controlled to collect the intensity of the light signal reflected from the surface of the workpiece by the light signal emitted by the light source at a preset frequency to obtain multiple sets of sampling points. The multiple sets of sampling points correspond to the multiple first defocus amounts. Each set of sampling points includes M1 sampling points; M1 is an integer greater than 1; each sampling point corresponds to a light intensity value. The sequence number of the sampling point corresponding to the maximum light intensity value in each of the M1 sampling points in each group is determined to obtain multiple first sequence numbers; the multiple first sequence numbers correspond to the multiple first defocus amounts. The correspondence between the serial number and the defocus amount is determined based on the plurality of first serial numbers and the plurality of first defocus amounts.

3. The method according to claim 2, characterized in that, The method further includes: Acquire multiple frames of first light intensity signal curves, each frame of which is obtained based on the photoelectric sensor periodically collecting the light signal intensity reflected by the workpiece during the process of the laser head emitting detection light to the workpiece; The light intensity signal curves with abnormal waveforms in the multi-frame first light intensity signal curves are removed to obtain the multi-frame second light intensity signal curves; each frame of the multi-frame second light intensity signal curve includes M2 first sampling points; The sequence number of the second sampling point among the M2 first sampling points included in each frame of the second light intensity signal curve is determined to obtain multiple second sequence numbers; the second sampling point is the sampling point corresponding to the maximum light intensity value among the M2 first sampling points; Based on the plurality of second serial numbers and the correspondence between the serial numbers and the defocus amount, a plurality of second defocus amounts are determined, wherein the plurality of second defocus amounts correspond to the plurality of second serial numbers; The defocus amount of the laser head is determined based on the plurality of second defocus amounts.

4. The method according to claim 3, characterized in that, Any frame of the first light intensity signal curve Q in the multi-frame first light intensity signal curves includes M2 first sampling points. Whether the first light intensity signal curve Q is an abnormal curve is determined by the following method: Determine the number of zero-crossing sampling points among the M2 first sampling points; the zero-crossing sampling point is the sampling point corresponding to the maximum or minimum light intensity value among multiple sampling points with consecutive acquisition time among the M2 first sampling points, and the light intensity value corresponding to the multiple sampling points with consecutive acquisition time is neither monotonically increasing nor monotonically decreasing in time; If the number of zero-crossing sampling points among the M2 first sampling points is lower than the sampling point threshold, then the first light intensity signal curve Q is determined to be an abnormal curve.

5. The method according to claim 4, characterized in that, Determining the number of zero-crossing sampling points among the M2 first sampling points includes: Determine the light intensity value corresponding to each of the M2 first sampling points and the difference between each first sampling point and the previous first sampling point that is adjacent to it in terms of acquisition time; The number of zero-crossing sampling points among the M2 first sampling points is determined based on the differences corresponding to the plurality of first sampling points; The zero-crossing sampling points satisfy the following conditions: The signs of the N first differences corresponding to the N first sampling points that are temporally adjacent to the zero-crossing sampling point are all first signs, and the signs of the N second differences corresponding to the N last N first sampling points that are temporally adjacent to the zero-crossing sampling point are all second signs; where N is an integer greater than 1 and not greater than half the number of the first sampling points; The first symbol is the opposite of the second symbol; The acquisition time of the zero-crossing sampling point is located in the middle of the acquisition time range of the first light intensity signal curve Q.

6. The method according to claim 3, characterized in that, The maximum value of the light intensity corresponding to the sampling point in the first light intensity signal curve exceeds the light intensity threshold.

7. The method according to any one of claims 3-6, characterized in that, Determining the defocus amount of the laser head based on the plurality of second defocus amounts includes: The larger and smaller T values ​​among the plurality of second defocus values ​​are removed to obtain one or more third defocus values; where T is an integer greater than 0 and not greater than half the number of second defocus values; The defocus amount of the laser head is determined based on the one or more third defocus amounts.

8. The method according to claim 3, characterized in that, During the process of the laser head emitting detection light towards the workpiece, the focal length of the variable focal length element in the laser head changes according to a first cycle, and each first light intensity signal curve is acquired when the focal length of the variable focal length element changes for one complete cycle.

9. The method according to claim 8, characterized in that, The method further includes: During the process of the laser head emitting detection light towards the workpiece, the detection light emitted by the laser head is controlled to traverse multiple measurement points on the workpiece according to a second cycle; The second period is shorter than the first period.

10. The method according to claim 9, characterized in that, The method further includes: Select a point on the surface of the workpiece as the first measurement point; Multiple second measurement points are determined around the first measurement point, and the distance between each second measurement point and the first measurement point is less than a first preset distance. The multiple measurement points include the first measurement point and the multiple second measurement points.

11. The method according to claim 10, characterized in that, The plurality of second measurement points are arranged in a matrix or a ring around the first measurement point, or in a spiral arrangement starting from the first measurement point.

12. An industrial control computer, characterized in that, The industrial control computer is used in the laser focus measurement system, which also includes optical measurement equipment, including: a variable focal length element, a collimating element, a beam splitter, and a photoelectric sensor. The detection light emitted by the light source passes through the beam splitter, the variable focal length element, and the collimating element; wherein, the collimating element collimates the detection light into parallel light, and the parallel light is focused onto the surface of the workpiece by the optical converging element of the laser head or an optical converging element independent of the laser head; the light source measurement light reflected from the surface of the workpiece enters the optical measurement device in reverse through the optical converging element, and then passes through the collimating element, the variable focal length element, and the beam splitter to the photoelectric sensor; The industrial control computer includes: The acquisition unit is used to acquire multiple detection points formed on the surface of the workpiece by the laser head using the detection light; The control unit is used to control the up-and-down movement of the laser head during the process of forming the plurality of detection points on the surface of the workpiece; A recording unit is used to record a first correspondence between the distance between the laser head and the surface of the workpiece when each detection point is formed and each detection point; The acquisition unit is further configured to acquire a multi-frame light intensity signal curve for each of the plurality of detection points, wherein the multi-frame light intensity signal curve for each detection point is the light intensity signal curve reflected by the surface of the workpiece during the formation of each detection point; The determining unit is used to determine a target detection point from the plurality of detection points based on the multi-frame light intensity signal curve of each detection point, wherein the multi-frame light intensity signal curve of the target detection point satisfies a preset condition; the multi-frame light intensity signal curve of the target detection point is the reflected light signal corresponding to the detection light when the focal length is correctly adjusted periodically; based on the first correspondence and the target detection point, the distance between the laser head and the surface of the workpiece when the target detection point is formed is determined, and the distance between the laser head and the surface of the workpiece when the target detection point is formed is determined as the focal length of the light output signal of the laser head.

13. An electronic device, characterized in that, The system includes a processor connected to a memory for storing computer programs, and the processor for executing the computer programs stored in the memory to cause the industrial control computer to perform the method as described in any one of claims 1-11.

14. A laser welding control system, comprising: A laser welding system, a multi-optical sensor module, a signal processing module, and an industrial control computer, characterized in that the industrial control computer is used to execute the method as described in any one of claims 1-11.

15. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement the method as described in any one of claims 1-11.

16. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the method described in any one of claims 1-11.

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