Visual positioning method for welding thermoplastic material to metal material

Abstract

The present application relates to the technical field of image processing, in particular to a kind of thermoplastic material and metal material's welding visual positioning method.The method monitors the moving track of the material to be docked in the docking process in real time and records, finally forms the moving track curve with obvious characteristics, based on moving track curve can effectively analyze the positioning error of the material to be docked when moving, in the welding process of two materials, the material accumulation of end surface area is detected, and the positioning deformation in the welding process can be reflected by the material accumulation, i.e. finally positioning adjustment function can be constructed by end surface unevenness and positioning error, the positioning defects generated in the docking process and the welding process can be adjusted by using positioning adjustment function, and then the welding quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image processing, in particular to a visual positioning method for welding thermoplastic materials and metal materials. BACKGROUND

[0002] Thermoplastic composite materials, as a new type of lightweight material, have been widely used in the field of aerospace. The joining of dissimilar materials between metal and thermoplastic composite materials has attracted widespread attention due to its ability to fully utilize the respective advantages of both materials. Friction stir welding, as a low heat input welding technology, has shown great application potential in the field of dissimilar welding between metal and thermoplastic composite materials. This process uses the friction heat between a high-speed rotating stir head and the workpiece as the heat input for welding, and has the advantages of short process cycle, simple operation, and no environmental pollution. Due to the significant differences in thermal expansion coefficient, thermal conductivity, melting point, and other aspects between thermoplastic materials and metal materials, problems such as thermal stress and deformation are prone to occur during welding. Therefore, high-precision positioning technology is crucial to ensure the accuracy of the welding position. Through visual positioning systems and image processing algorithms, sub-millimeter positioning accuracy can be achieved. By monitoring and feedback in real time, errors during the welding process can be compensated for, improving the precision and consistency of the welding.

[0003] In actual positioning process, because the material itself is not a straight shape, the material will cause positioning error during the butt friction process due to shape problems. The positioning error will cause uneven friction heating, and further cause welding defects in the end face welding process. SUMMARY

[0004] In order to solve the technical problems that the existing technology cannot identify the positioning error in the butt joint process, and the friction deformation in the welding process, resulting in poor welding effect, the purpose of the present application is to provide a visual positioning method for welding thermoplastic materials and metal materials, and the technical scheme adopted is as follows:

[0005] The present application provides a visual positioning method for welding thermoplastic materials and metal materials, which comprises:

[0006] Any one of the thermoplastic material and the metal material is taken as the fixed material, and the other material is taken as the butt joint material. During the movement of the butt joint material to the fixed material for welding, the movement trajectory curve of the butt joint material and the welding end face image are obtained.

[0007] According to the fluctuation of the movement trajectory curve, the positioning error is obtained. In the end face region of the welding end face image, a search window is constructed with the end face region as the center. According to the change of pixel value between different preset regions in the search window, the end face unevenness of accumulation is obtained.

[0008] A positioning adjustment function is constructed on the basis of a Gaussian function according to the end face accumulation unevenness and the positioning error; and the positioning adjustment function is used to control the positioning of the two kinds of welding materials.

[0009] Further, the method for obtaining the movement trajectory curve comprises:

[0010] A movement image of the butt joint material during the butt joint process is collected by using a fixed camera installed on the fixed material; the end face of the butt joint material is included in the movement image; the movement trajectory curve is drawn by taking the centroid point of the end face of the butt joint material as a reference point, taking the horizontal distance of the reference point during each movement process as the horizontal coordinate, and taking the vertical distance as the vertical coordinate.

[0011] Further, the method for obtaining the positioning error comprises:

[0012] The positioning feature of the reference point in the movement image is obtained according to the coordinates of the reference point, and the fluctuation degree of the positioning feature during the movement process of the butt joint material is obtained.

[0013] The movement trajectory curve is decomposed to obtain the period, the trend item and the residual item of the movement trajectory curve; and the curve fluctuation of the movement trajectory curve is obtained according to the period, the trend item and the residual item.

[0014] The positioning error is obtained according to the fluctuation degree and the curve fluctuation.

[0015] Further, the method for obtaining the fluctuation degree comprises:

[0016] The product of the range and the variance of the positioning feature during the movement process of the butt joint material is taken as the fluctuation degree.

[0017] Further, the method for obtaining the curve fluctuation comprises:

[0018] The product of the variance of the data in the residual item and the mean value in the trend item is multiplied, and the ratio of the product to the period size is taken as the curve fluctuation.

[0019] Further, the method for obtaining the end face accumulation unevenness comprises:

[0020] In the search window, an analysis region is sequentially constructed according to a preset step length with the end face region as the center, and a normal material region is taken as a comparison region; the pixel value difference between each scale analysis region and the comparison region is analyzed to obtain the end face accumulation degree; the pixel value distribution stability in each scale analysis region is analyzed to obtain the end face accumulation roughness degree; and the end face accumulation unevenness is obtained according to the end face accumulation degree and the end face accumulation roughness degree.

[0021] Further, the method for obtaining the end face accumulation degree comprises:

[0022] The difference between the average gray value of each analysis region and the corresponding contrast region is taken as the stacking feature of each analysis region, and the cumulative value of all analysis regions is taken as the end face accumulation degree.

[0023] Further, the method for obtaining the end face accumulation roughness comprises:

[0024] For each scale analysis region, the difference between the gray value of each pixel point in the analysis region and the average gray value of the analysis region is taken as the gray deviation of each gray value, and the average gray deviation of all pixel points in the analysis region is taken as the roughness of the analysis region.

[0025] The average roughness of all analysis regions is taken as the end face accumulation roughness.

[0026] Further, the expression of the positioning adjustment function is:

[0027] Wherein f represents the value of the positioning adjustment function, K is the end face accumulation unevenness, q represents the positioning error, X represents the position deviation of the current position of the butt joint material and the butt joint material at the previous time, e represents the natural constant; when the welding has not started, X is a positive integer 1.

[0028] Further, the method for obtaining the positioning feature comprises:

[0029] The coordinates of the reference point in the moving image are obtained, and the Euclidean distance between the coordinates and the origin of the moving image is taken as the positioning feature.

[0030] The present application has the following beneficial effects:

[0031] The present application monitors and records the moving trajectory of the butt joint material in the butt joint process in real time, finally forming a moving trajectory curve with obvious features, and based on the moving trajectory curve, the positioning error of the butt joint material during movement can be effectively analyzed, and then the positioning control can be performed according to the positioning error. Further in the welding process of two materials, the material accumulation of the end face region is detected, and the positioning deformation in the welding process can be reflected through the material accumulation, that is, the positioning adjustment function can be finally constructed by the end face accumulation unevenness and the positioning error, and the positioning defects generated in the butt joint process and the welding process can be adjusted and controlled by using the positioning adjustment function, thereby improving the welding quality. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, and the advantages thereof, below will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0033] Figure 1 A welding schematic diagram of a welding process of a thermoplastic material and a metal material provided by an embodiment of the present application;

[0034] Figure 2 A flowchart of a welding visual positioning method of a thermoplastic material and a metal material provided by an embodiment of the present application;

[0035] Figure 3 A moving trajectory curve schematic diagram provided by an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined inventive purpose, below, the specific embodiments, structures, features and effects of a welding visual positioning method of a thermoplastic material and a metal material according to the present application are described in detail in combination with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0038] The application scenario of the embodiment of the present application is a friction stir welding process of a thermoplastic material and a metal material, please refer to Figure 1 which shows a welding schematic diagram of a welding process of a thermoplastic material and a metal material provided by an embodiment of the present application. In the welding process, one material is selected as a fixed material. The embodiment of the present application takes the welding material B as the fixed material and deploys a camera above the fixed material. The welding material A is a butt joint material. The two welding materials are fixed by a fixed clamp, and the welding material A is controlled to butt joint with the welding material B. After the butt joint is completed, high-speed rotation is performed. The rotation friction generates a large amount of heat to melt the contact surface of the two materials, thereby realizing welding.

[0039] Below, the specific scheme of a welding visual positioning method of a thermoplastic material and a metal material provided by the present application is described in detail in combination with the drawings.

[0040] Please refer toFigure 2 Fig. 9 shows a flow chart of a method for visual positioning of welding between thermoplastic material and metal material according to an embodiment of the present application, which comprises the following steps:

[0041] Step S1: taking one of the thermoplastic material and the metal material as a fixed material and the other as a butt joint material; obtaining a moving trajectory curve of the butt joint material and a welding end surface image during movement of the butt joint material to the fixed material for welding.

[0042] In the embodiment of the present application, the metal material is selected as the fixed material and the thermoplastic material is selected as the butt joint material. During butt joint of the butt joint material, the image of the butt joint material is collected by computer vision method, and the moving trajectory curve of the butt joint material is drawn, and the positioning error and other information during movement of the butt joint material can be determined according to the moving trajectory curve. Further, the welding end surface image of the contact surface of the two materials is collected during butt joint welding, and the positioning defects during friction welding can be further determined by determining the material accumulation of the welding end surface in the subsequent steps.

[0043] Preferably, in the embodiment of the present application, the method for obtaining the moving trajectory curve comprises:

[0044] The moving image of the butt joint material during butt joint is collected by the fixed camera installed on the fixed material, and the end surface of the butt joint material is included in the moving image. In the embodiment of the present application, considering that the material end surface of the friction welding has a specific shape, such as a circle, a rectangle, etc., the edge detection can be performed on the moving image, and the end surface area is obtained by recognizing the shape of the edge contour. It should be noted that the edge detection and contour recognition method are well known to those skilled in the art, and will not be described here.

[0045] The moving trajectory curve is drawn by taking the centroid point of the end surface of the butt joint material as a reference point, taking the horizontal distance of the reference point during each movement as the horizontal coordinate, and taking the vertical distance as the vertical coordinate. Please refer to Figure 3 Fig. 10 shows a moving trajectory curve diagram according to an embodiment of the present application.

[0046] In the embodiment of the present application, the position data of the butt joint material is collected once per second, and the moving trajectory curve is constructed.

[0047] Step S2: obtaining the positioning error according to the fluctuation of the moving trajectory curve; constructing a search window with the end surface area as the center in the end surface area of the welding end surface image, and obtaining the end surface accumulation unevenness according to the pixel value change between different preset areas in the search window.

[0048] In the process of butting the butt joint material and the fixed material, because of the mechanical vibration and the shape of the material, there is a certain bending deformation in the butting process, which further causes the positioning error to occur. The moving track curve can represent the position characteristics in the moving process of the butt joint material, and thus the positioning error in the butting process can be obtained according to the volatility of the moving track curve, that is, the greater the volatility, the more the positioning error occurs.

[0049] Preferably, in the embodiment of the present application, the positioning error obtaining method comprises:

[0050] The positioning characteristics of the reference point in the moving image are obtained according to the coordinates of the reference point. The positioning characteristics are used to convert the two-dimensional coordinate information into one-dimensional numerical characteristic data, which can facilitate the quantification of the position of the reference point. Further, the change volatility of the positioning characteristics in the moving process of the butt joint material can be obtained, that is, the change volatility can be obtained by counting the change of the positioning characteristics in the whole butting process.

[0051] In order to analyze the volatility of the moving track curve, the moving track curve is decomposed to obtain the period, trend item and residual item of the moving track curve. The curve volatility of the moving track curve is obtained according to the period, trend item and residual item. That is, the smaller the period, the greater the number of changes on the curve, and the greater the volatility; the greater the trend item, the more complex the trend change, and the greater the curve volatility; the greater the residual item, the more obvious the fluctuation of the curve, and the greater the volatility.

[0052] The positioning error is obtained according to the change volatility and the curve volatility. In the embodiment of the present application, after the change volatility and the curve volatility are quantified, the product of the two is taken as the positioning error.

[0053] In the embodiment of the present application, the positioning characteristics obtaining method comprises:

[0054] The coordinates of the reference point in the moving image are obtained, and the Euclidean distance between the coordinates and the origin of the moving image is taken as the positioning characteristics. That is, the positioning characteristics of the reference point are effectively quantified by the Euclidean distance.

[0055] Further, the change volatility obtaining method comprises:

[0056] Because the position data of the butt joint material is obtained according to a certain sampling frequency, the positioning characteristics also have a certain sampling frequency, and a set of positioning characteristics is obtained in the butting process. The product of the range and the variance of the positioning characteristics in the moving process of the butt joint material is taken as the change volatility. The greater the range, the greater the change amplitude of the positioning characteristics, and the greater the variance, the greater the change degree of the positioning characteristics, and thus the product of the two can effectively represent the change volatility.

[0057] Further, the method for obtaining the curve fluctuation includes:

[0058] The curve fluctuation is obtained by multiplying the variance of the data in the residual term and the mean value in the trend term, and taking the ratio of the product to the period size as the curve fluctuation. In the embodiment of the present application, the STL decomposition algorithm is used to decompose the moving track curve, and the specific method is a technical means known to those skilled in the art, which is not described here. The positive and negative correlation relationship is constructed by the product and the ratio method in the embodiment of the present application, and the effective quantification of the curve fluctuation is realized.

[0059] In the friction welding process, heat is generated by high-speed rotation and friction of two materials to melt and weld the end faces of the two materials. Under this process, the thermoplastic material will deform more than the metal material due to its soft nature, and this deformation will cause uneven stress of the material in the friction welding process, thereby causing new positioning errors and welding defects. In the friction welding process, in order to be able to weld the welding port firmly, a certain horizontal pressure will be applied to the welding material, thereby causing a certain degree of excess material deformation of the welding material, that is, the friction port appears to be stacked with material, and the welding material will slowly move towards the welding port. Therefore, the welding quality can be determined by monitoring the excess material accumulation in the end face area during the friction welding process to determine whether an error has occurred. That is, the greater the degree of excess material accumulation, the more positioning offset is generated during the welding process, resulting in an increase in excess material. Therefore, the image processing technology is used in the embodiment of the present application to determine the end face area in the welding end face image, and then a search window is constructed with the end face area as the center, and the pixel value change between different preset areas in the search window is analyzed to obtain the end face accumulation non-uniformity. That is, the excess material accumulation will appear in the search window, and the pixel value of the accumulation area will certainly change significantly from the non-accumulation area, so that the end face accumulation non-uniformity of the excess material on the end face can be effectively obtained by analyzing different areas in the search window.

[0060] In the embodiment of the present application, because the welding end face image is an image that has started the welding process, the end faces of the two materials have contacted, so the end face area should form a line segment on the image, and the line segment formed by the end face area can be directly obtained by edge detection.

[0061] Preferably, in an embodiment of the present application, the method for obtaining the end face accumulation non-uniformity includes:

[0062] In the search window, the analysis region is sequentially constructed in a preset step length and centered on the end face region. In the embodiment of the present application, the search window is set to be a region expanded to both sides of the end face region for twenty times, and the step length of each expansion is one pixel point, that is, the final search window is a rectangular region with a length of 41 and a width of the length of the line segment formed by the end face region. The construction compensation of the analysis region is set to be 2, that is, the region formed by each outward expansion of 2 pixel point units. Taking the analysis region constructed for the first time as an example, the analysis region should be a rectangular region with a length of 5 and a width of the length of the line segment formed by the end face region; the analysis region constructed for the second time is a rectangular region with a length of 9 and a width of the length of the line segment formed by the end face region. The expansion is continuously performed until the analysis region coincides with the search window, and the analysis is ended.

[0063] Because the analysis region is expanded centered on the end face region, the accumulation of the excess material is preferentially represented in the analysis region, and the contrast region is a normal material region without accumulation of the excess material. The excess material accumulation region presents a bright feature due to the influence of high temperature, and the normal material region is relatively dark. Therefore, the pixel value difference between each scale analysis region and other regions in the search window is analyzed to obtain the end face accumulation degree. That is, the greater the pixel value difference between the two regions, the more likely the analysis region is the excess material accumulation region, and the greater the end face accumulation degree.

[0064] The accumulation of the excess material not only presents a bright feature in the image, but also presents a texture feature of the surface of the excess material. Therefore, the pixel value distribution stability in each scale analysis region is further analyzed to obtain the end face accumulation roughness. That is, the worse the pixel value distribution stability in the analysis region, the richer the texture feature, and the more likely the analysis region is the excess material accumulation region.

[0065] The end face accumulation unevenness is obtained according to the end face accumulation degree and the end face accumulation roughness. In the embodiment of the present application, the end face accumulation degree and the end face roughness are quantified and then multiplied, and the product is taken as the end face accumulation unevenness.

[0066] Further, in the embodiment of the present application, the method for obtaining the end face accumulation degree comprises:

[0067] The difference between the average gray value of each analysis region and the corresponding contrast region is taken as the material accumulation feature of each analysis region. That is, the greater the difference between the average gray values, the brighter the analysis region, and the more likely the analysis region is formed by the accumulation of the excess material. The cumulative value of all analysis regions is taken as the end face accumulation degree.

[0068] Further, in the embodiment of the present application, the method for obtaining the end face accumulation roughness comprises:

[0069] For each scale analysis region, the difference between the gray value of each pixel in the analysis region and the average gray value of the analysis region is taken as the gray deviation of each gray value; the average gray deviation of all the pixel points in the analysis region is taken as the roughness of the analysis region. The greater the average gray deviation, the more uneven the pixel value distribution in the analysis region, the stronger the texture feature, and the greater the roughness in the region.

[0070] Because there are multiple scale analysis regions in the search window, the average roughness of all the analysis regions is taken as the end face accumulation roughness degree.

[0071] Step S3: constructing a positioning adjustment function based on the Gaussian function according to the end face accumulation unevenness and the positioning error; and controlling the positioning of the two kinds of welding materials by using the positioning adjustment function.

[0072] Based on the above steps, the analysis result of real-time visual monitoring based on image information in the butt joint process and the welding process can be obtained, and the positioning adjustment function in the positioning process can be constructed based on the end face accumulation unevenness and the positioning error. In the embodiment of the present application, the high-speed function is taken as the target function, and through the special function shape of the Gaussian function, the positioning process can be effectively controlled and responded.

[0073] Preferably, in the embodiment of the present application, the expression of the positioning adjustment function is:

[0074] Wherein f represents the positioning adjustment function value, K represents the end face accumulation unevenness, q represents the positioning error, X represents the position deviation of the butt joint material at the current position and the butt joint material at the previous moment, and e represents the natural constant; when the welding has not started, X is a positive integer 1. It should be noted that when the welding has not started, it means that this is the butt joint process, there is no welding process, and there is no analysis of the end face accumulation unevenness, so X can be directly set to 1, and only the positioning error information is retained.

[0075] It should be noted that X represents the position deviation of the butt joint material at adjacent moments, and the position of the butt joint material in the butt joint process is obtained by the end face of the butt joint material in the embodiment of the present application, so X can be set as the difference of the positioning features between two moments; and in the welding process, there is no complete material end face, only a line segment formed by the contact surface between the two materials, so the midpoint of the line segment is taken as the positioning point, and the positioning feature difference of the positioning point can also be obtained to obtain X.

[0076] The control module of the welding device can refer to the output result of the positioning adjustment function to adaptively control the adjustment amount and perform positioning adjustment. The specific adjustment feedback method is a technical means familiar to those skilled in the art, and will not be described here.

[0077] To sum up, the embodiment of the present application monitors and records the moving track of the butt joint material in the butt joint process in real time, finally forms the moving track curve with obvious characteristics, can effectively analyze the positioning error of the butt joint material when moving based on the moving track curve, detects the material accumulation condition of the end face area in the welding process of the two materials, can reflect the positioning deformation in the welding process through the material accumulation condition, that is, finally can construct the positioning adjustment function through the end face accumulation unevenness and the positioning error, the positioning defects generated in the butt joint process and the welding process can be adjusted and controlled by using the positioning adjustment function of the present application, and the welding quality is further improved.

[0078] It should be noted that the above-mentioned embodiment sequence of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are also possible or can be advantageous.

[0079] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the difference from other embodiments.

Claims

1. A visual positioning method for welding thermoplastic materials and metal materials, characterized in that: The method comprises: Any one of the thermoplastic material and the metal material is used as a fixed material, and the other material is used as a butt joint material; during the process of the butt joint material moving to the fixed material for welding, a movement trajectory curve of the butt joint material and a welding end face image are obtained; A positioning error is obtained based on the fluctuation of the movement trajectory curve; a search window is constructed with the end face area in the end face image as the center, and the end face stacking unevenness is obtained based on the change of pixel values ​​between different preset areas in the search window; A positioning adjustment function is constructed based on the Gaussian function according to the end face stacking unevenness and the positioning error; and the positioning of the two welding materials is controlled by using the positioning adjustment function.

2. The method for visually positioning a thermoplastic material and a metal material for welding according to claim 1, characterized in that: The method for obtaining the movement trajectory curve includes: A fixed camera installed on the fixed material collects moving images of the docking materials during the docking process; the moving images include the end faces of the docking materials, and the center of mass of the end faces of the docking materials is used as a reference point. The lateral distance of the reference point during each movement is used as the horizontal coordinate, and the longitudinal distance is used as the vertical coordinate to draw the moving trajectory curve.

3. The method for visual positioning of welding thermoplastic material and metal material according to claim 2, characterized in that: The method for obtaining the positioning error includes: Obtaining a positioning feature of the reference point in the moving image according to the coordinates of the reference point, and obtaining a degree of change and fluctuation of the positioning feature during the movement of the docking material; Decomposing the movement trajectory curve to obtain a period, a trend term, and a residual term of the movement trajectory curve; and obtaining a curve volatility of the movement trajectory curve according to the period, the trend term, and the residual term; The positioning error is obtained according to the variation fluctuation degree and the curve fluctuation.

4. The method for visually positioning a thermoplastic material and a metal material for welding according to claim 3, characterized in that: The method for obtaining the degree of change fluctuation includes: The product of the range and the variance of the positioning feature during the movement of the butted materials is taken as the variation fluctuation degree.

5. The method for visual positioning of welding thermoplastic material and metal material according to claim 3, characterized in that: The method for obtaining the curve volatility includes: The variance of the data in the residual term and the mean value in the trend term are multiplied, and the ratio of the product to the cycle size is used as the curve volatility.

6. The method for visual positioning of welding thermoplastic material and metal material according to claim 1, characterized in that: The method for obtaining the end face stacking unevenness includes: In the search window, analysis areas are constructed in sequence according to a preset step size with the end face area as the center, and the normal material area is used as the comparison area; the pixel value difference between the analysis area and the comparison area at each scale is analyzed to obtain the end face stacking degree; the pixel value distribution stability within the analysis area at each scale is analyzed to obtain the end face stacking roughness; the end face stacking unevenness is obtained based on the end face stacking degree and the end face stacking roughness.

7. The method for visually positioning a thermoplastic material and a metal material for welding according to claim 6, characterized in that: The method for obtaining the end face accumulation degree includes: The difference in the mean grayscale value between each analysis area and the corresponding comparison area is used as the pile material appearance feature of each analysis area; and the accumulated value of all analysis areas is used as the end face accumulation degree.

8. The method for visually positioning welding of thermoplastic material and metal material according to claim 6, characterized in that: The method for obtaining the end face accumulation roughness comprises: For each scale analysis area, the difference between the grayscale value of each pixel in the analysis area and the grayscale mean of the analysis area is taken as the grayscale deviation of each grayscale value; the average grayscale deviation of all pixels in the analysis area is taken as the roughness of the analysis area; The average roughness of all analyzed areas is taken as the end surface stacking roughness.

9. The method for visual positioning of welding thermoplastic material and metal material according to claim 1, characterized in that: The expression of the positioning adjustment function is: Wherein f represents the positioning adjustment function value, K is the end face stacking unevenness, q represents the positioning error, X represents the positional deviation between the butt joint material at the current position and the butt joint material at the previous moment, and e represents a natural constant. When welding has not started, X is a positive integer 1.

10. The method for visual positioning of welding thermoplastic material and metal material according to claim 3, characterized in that: Methods for obtaining positioning features include: The coordinates of the reference point in the moving image are obtained, and the Euclidean distance between the coordinates and the origin of the moving image is used as the positioning feature.

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