A welding robot path automatic planning system

Abstract

The application belongs to the technical field of welding robots, and discloses a welding robot path automatic planning system, which comprises a data input module, a contour line module, a bevel module, a pointing module and a center line module; the data input module is used for inputting weld contour line data of Y-shaped welds; the contour line module is used for fitting the weld contour line into a contour line equation based on the weld contour line data; the bevel module is used for determining a land, a slope line, a bevel positive direction and a bevel polygon of the bevel based on the contour line equation; the pointing module is used for calculating a welding gun profile pointing direction based on the slope line and the bevel positive direction of the bevel; and the center line module is used for calculating a weld center line based on the bevel polygon and the bevel positive direction; the welding defect occurrence risk is remarkably reduced, and the stability and reliability of the overall welding process are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding robots, and more particularly, to a welding robot path automatic planning system. BACKGROUND

[0002] In current welding robot applications, the welding seam recognition technology usually relies on image processing, laser detection or point cloud data, etc. After preliminary processing, a relatively simple geometric model is used to calculate the welding seam center line. This method can meet the basic requirements when dealing with simple or approximately symmetric welding seams, but when dealing with complex curve welding seams, the center line calculation method is often too rough to accurately reflect the true geometry of the welding seam. More complex is that when the groove design of the welding seam section is asymmetric, it is difficult for the traditional method to determine which point or curve can represent the "center axis" of the welding seam, which will directly affect the planning of the welding path and the stability of the welding quality. Therefore, how to accurately calculate the welding seam center line under the condition of complex curve and asymmetric section has become a key technical problem to be solved.

[0003] In view of this, the present application provides a welding robot path automatic planning system to solve the above problems. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art and achieve the above-mentioned purposes, the present application provides the following technical scheme: a welding robot path automatic planning system, comprising:

[0005] A data input module for inputting welding seam contour line data of a Y-shaped welding seam;

[0006] A contour line module for fitting the welding seam contour line into a contour line equation based on the welding seam contour line data;

[0007] A groove module for determining a land, a bevel and a groove polygon of the groove based on the contour line equation, and determining a positive direction of the groove based on the land of the groove;

[0008] A pointing module for calculating a welding gun section pointing direction based on the bevel of the groove and the positive direction of the groove;

[0009] A center line module for calculating a welding seam center line based on the groove polygon and the positive direction of the groove;

[0010] A path planning module for combining the welding seam center lines of all positions of the welding seam of a welding object into a welding seam center line set, and the welding seam center line set being a welding path of the welding robot for the welding object.

[0011] Further, the weld contour line data are spatial coordinates of sampling points on the weld contour line; the weld contour line comprises a left side edge line, a right side edge line, a left side throat line, a right side throat line, a left side root line, and a right side root line of the welding joint.

[0012] The method for obtaining the weld contour line data comprises: capturing a weld image or scanning a workpiece surface by a 3D camera and a laser sensor, extracting weld feature points, classifying the weld feature points into points on the left side edge line, the right side edge line, the left side throat line, the right side throat line, the left side root line, and the right side root line according to positions of the weld feature points, recording spatial coordinates of the weld feature points, and obtaining the weld contour line data.

[0013] Further, the fitting method of the weld contour line comprises: taking any one of all the weld contour lines as a reference line, predefining a contour line equation of the reference line, and respectively predefining displacement vectors of the remaining weld contour lines relative to the reference line; removing abnormal points of the weld contour line data, fitting all the weld contour line data into corresponding contour line equations respectively by using a least square method, and obtaining contour line equations of the weld contour lines having a generalized parallel relationship with each other; the contour line equation comprises a polynomial or a B-spline curve.

[0014] Further, the method for calculating the bevel polygon comprises: taking points of the contour line equations in a cross section as vertices of the polygon, and obtaining the bevel polygon.

[0015] The vertices of the bevel polygon are a left edge point, a right edge point, a left throat point, a right throat point, a left root point, and a right root point; a line segment with the left edge point and the right edge point as end points is defined as a first side of the bevel polygon.

[0016] The method for calculating the blunt edge comprises: subtracting the left throat point from the left root point to obtain a left blunt edge; and subtracting the right throat point from the right root point to obtain a right blunt edge.

[0017] The method for calculating the slope line comprises: subtracting the left throat point from the left edge point to obtain a left slope line; and subtracting the right throat point from the right edge point to obtain a right slope line.

[0018] The method for calculating the bevel positive direction comprises: calculating a vector sum of the left blunt edge and the right blunt edge, and performing unitization on the vector sum to obtain the bevel positive direction.

[0019] Further, the calculation method of the pointing direction of the welding gun profile comprises the following steps: calculating an included angle one between the right side slope line and the positive direction of the groove; calculating an included angle two between the left side slope line and the positive direction of the groove; subtracting the included angle two from the included angle one, multiplying the preset coefficient to obtain a deflection angle; determining a rotation direction of the positive direction of the groove in the profile according to the deflection angle, if the deflection angle is positive, rotating clockwise, if the deflection angle is negative, rotating counterclockwise; taking the outer product of the tangent direction vector of the left side edge line and the positive direction of the groove as a rotation axis; rotating the positive direction of the groove around the rotation axis by the deflection angle in the profile to obtain the pointing direction of the welding gun profile.

[0020] Further, the calculation method of the welding seam center line comprises the following steps:

[0021] Based on the groove polygon and the positive direction of the groove, a center line coefficient is solved; a vector from the left edge point to the right edge point is multiplied by the center line coefficient, and the left edge point is added to obtain the welding seam center line.

[0022] Further, the solving method of the center line coefficient comprises the following steps:

[0023] Step 1, setting two parameters of interval left end and interval right end of the range of the center line coefficient value, let the interval left end be 0 and the interval right end be 1; calculating the total area of the groove polygon;

[0024] Step 2, calculating the average value of the interval left end and the interval right end, taking the average value as the initial center line coefficient, calculating the intersection point of the polygon bisector and the groove polygon, calculating the left half area of the left part of the groove polygon on the polygon bisector; the area of the polygon is calculated by using the shoelace formula;

[0025] Step 3, if the difference between the left half area and half of the total area is less than a preset small amount, output the initial center line coefficient of step 2 as the center line coefficient, and determine the welding seam center line according to the center line coefficient; otherwise, if the left half area is less than half of the total area, let the interval left end be equal to the initial center line coefficient of step 2, repeat step 2; if the left half area is greater than half of the total area, let the interval right end be equal to the center line coefficient of step 2, repeat step 2.

[0026] Further, the polygon bisector is a straight line that divides the area of the groove polygon in the profile; the tangent direction of the polygon bisector is the same as the positive direction of the groove.

[0027] Further, the generalized parallel relationship is that a line segment with a fixed length moves in space along a direction perpendicular to itself, and two space curves are formed by the trajectories of the two end points of the line segment.

[0028] The welding robot path automatic planning system has the following advantages:

[0029] Traditional algorithms are usually based on simplified geometric model or symmetry assumption, when dealing with complex spatial curve weld and asymmetric groove structure, there are inherent defects such as large deviation of center axis positioning, insufficient heat conduction compensation, etc. The present application innovatively uses the area division polygon bisector to accurately calculate the weld center line, so as to better meet the strict requirements of heat input balance in welding process; secondly, the angle difference compensation mechanism is created, the left and right groove angle difference value is analyzed, the welding gun profile direction is calculated to optimize the welding gun posture in three-dimensional space; significantly improve the process stability and joint reliability under the working condition of three-dimensional asymmetric variable curvature (the curvature of complex spatial curve is generally variable). BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the weld contour line of the present application;

[0031] Figure 2 It is a schematic diagram of the groove polygon of the present application;

[0032] Figure 3 It is a schematic diagram of a welding robot path automatic planning system module of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0034] Embodiment 1

[0035] Referring to Figure 3 , the welding robot path automatic planning system described in this embodiment comprises a data input module, a contour line module, a groove module, a pointing module, a center line module, a parameter setting module and a path planning module.

[0036] The data input module is used for inputting the weld contour line data of the Y-shaped weld.

[0037] The weld contour line comprises the left edge line A1, the right edge line A4, the left throat line A2, the right throat line A5, the left root line A3 and the right root line A6 of the welding joint, referring to Figure 1 . The weld contour line data is the spatial coordinates of the sampling points on the weld contour line.

[0038] The method for obtaining the weld contour line data comprises: capturing a weld image or scanning a workpiece surface by a 3D camera and a laser sensor, extracting weld feature points, classifying the weld feature points into points on a left side edge line A1, a right side edge line A4, a left side throat line A2, a right side throat line A5, a left side root line A3 and a right side root line A6 according to positions of the weld feature points, recording spatial coordinates of the weld feature points, and obtaining the weld contour line data. In the embodiment, "left" and "right" should be relative to the observation direction of the weld, and in actual application, the observation direction of the weld is determined first, and then "left" and "right" are determined. Figure 1 As can be seen, A1 is on the left and A4 is on the right; in actual application, the observation direction of the weld is determined first, and then "left" and "right" are determined by imagining that a person stands on the surface of the workpiece and faces the front direction of the tangent vector of any weld contour line.

[0039] The contour line module fits the weld contour line into a contour line equation based on the weld contour line data.

[0040] In the embodiment, the left side edge line A1, the right side edge line A4, the left side throat line A2, the right side throat line A5, the left side root line A3 and the right side root line A6 are spatial curves having a generalized parallel relationship with each other. The generalized parallel relationship can be understood as follows: a line segment with a fixed length moves in a direction perpendicular to itself in space, and two spatial curves are formed by the trajectories of the two end points of the line segment. The generalized parallel relationship keeps the tangent directions of the two spatial curves at the corresponding points the same and the distance constant. The generalized parallel relationship includes not only the strict parallel relationship obtained by simple translation but also the case of concentric circles obtained by rotating the line segment with a fixed length. Since the surface and the groove of the actual workpiece are uneven, the weld contour line is unclear, and the sensor for automatic recognition of the weld has errors, the obtained weld contour line data must be fitted into a smooth curve to facilitate subsequent calculation.

[0041] The fitting method of the weld contour line comprises: taking any one of all the weld contour lines (in the embodiment, the number of the weld contour lines of the Y-shaped weld is six) as a reference line, pre-setting a contour line equation of the reference line, and pre-setting displacement vectors of the remaining weld contour lines relative to the reference line; removing abnormal points of the weld contour line data, fitting all the weld contour line data into corresponding contour line equations by using the least square method, obtaining contour line equations of the weld contour lines having the generalized parallel relationship with each other, and the contour line equation comprises a polynomial or a B-spline curve (a segmented polynomial curve with certain smoothness at each node). ​​​​​​Axis coordinates ("x", "y", "z") This is a parametric definition of the space curve, which is the prior art. The right edge line is , the left throat line is , the right throat line is , the left root line is , and the right root line is ; , , , , The size of each is a constant, and all are perpendicular to the tangent direction vector of ; The tangent direction vector of is , ; ( represents the set of real numbers) ; , , represent the first derivative of , , respectively.

[0042] The groove module determines the bevel, slope line and groove polygon based on the contour line equation. The positive direction of the groove is determined based on the bevel of the groove. Since , , , and are coplanar vectors, let and lie in the plane of the section; the intersection of the section and the weld seam gives the groove (the shaded part in Figure 2 ).

[0043] The calculation method of the groove polygon includes: taking the six points of the contour line equation in the section as the six vertices of the polygon to obtain the groove polygon. The six vertices of the groove polygon are left edge point (Note that the left edge line is also denoted as , but , including all left edge points), right edge point , left throat point , right throat point , left root point and right root point The line segment with the left edge point and the right edge point as the endpoints is defined as the first side of the groove polygon; the line segment with the right edge point and the right throat point as the endpoints is defined as the second side of the groove polygon; the line segment with the right throat point and the right root point as the endpoints is defined as the third side of the groove polygon; the line segment with the right root point and the left root point as the endpoints is defined as the fourth side of the groove polygon; the line segment with the left root point and the left throat point as the endpoints is defined as the fifth side of the groove polygon; and the line segment with the left throat point and the left edge point as the endpoints is defined as the sixth side of the groove polygon.

[0044] The calculation method of the land includes: subtracting the left throat point from the left root point (the operation between points refers to the operation between the coordinates of the points), to obtain the left land, denoted as (the land here is actually a vector, because the calculation of the welding gun profile direction only needs the direction of the land); subtracting the right throat point from the right root point, to obtain the right land, denoted as The calculation formula of the left land includes: The calculation formula of the right land includes: .

[0045] The calculation method of the bevel includes: subtracting the left throat point from the left edge point, to obtain the left bevel, denoted as (the bevel here is actually a vector, because the calculation of the welding gun profile direction only needs the direction of the bevel); subtracting the right throat point from the right edge point, to obtain the right bevel, denoted as The calculation formula of the left bevel includes: The calculation formula of the right bevel includes: .

[0046] The calculation method of the groove normal includes: calculating the vector sum of the left land and the right land, and performing unitization on the vector sum, to obtain the groove normal, denoted as The calculation formula of the groove normal includes: , is the Euclidean norm of the vector. The groove normal is the reference direction of the groove, which defines the direction of the groove, and facilitates the definition of the welding gun profile direction and the calculation of the weld center line.

[0047] The pointing module calculates the welding gun profile direction based on the bevel of the groove and the groove normal. The calculation method of the welding gun profile direction includes: calculating the included angle one between the right bevel and the groove normal, denoted as ; calculating the included angle two between the left bevel and the groove normal, denoted as ; subtracting the included angle two from the included angle one, and multiplying by a preset coefficient, to obtain the deflection angle, denoted as ; the rotation direction of the bevel positive direction is determined according to the deflection angle in the profile, if the deflection angle is positive, the rotation direction is clockwise, if the deflection angle is negative, the rotation direction is counterclockwise; the outer product of the tangent direction vector of the left edge line A1 and the bevel positive direction is taken as the rotation axis; the welding torch profile pointing direction is obtained by using the Rodrigues' rotation formula, and is recorded as . The preset coefficient is obtained according to experimental calibration, and is recorded as ; the preset coefficient is used to adjust the sensitivity of the deflection angle to the angle difference between the first included angle and the second included angle. The method for determining the preset coefficient according to experimental calibration comprises the following steps: performing welding experiments under typical working conditions, testing the influence of different preset coefficients on the welding quality (such as penetration, width, and defect rate), and determining the optimal preset coefficient by data fitting or statistical analysis; the initial value of the preset coefficient is recommended to be equal to 1 (that is, the deflection angle directly uses the angle difference between the first included angle and the second included angle), and then the actual effect is fine-tuned. The preset coefficient is a key parameter connecting the process theory and the actual application, and needs to be adjusted through experimental calibration to ensure that the welding torch pointing direction can effectively compensate for the difference in heat conduction and does not deviate from the process stability requirement.

[0048] The specific calculation method of the welding torch profile pointing direction comprises the following steps:

[0049] In the formula, the welding torch profile pointing direction is , , , , is the tangent direction vector of the left edge line A1; is the outer product of the vector and the vector , is the inner product of the vector and the vector . The calculation formula of the welding torch profile pointing direction determines the rotation axis of the bevel positive direction The tangent direction vector of the left edge line A1 is rotated by the deflection angle. The greater the angle difference between the left and right bevel lines, the greater the angle of the welding torch profile deflection relative to the bevel normal. The welding torch profile points to adjust the angle of the welding torch, reduce welding defects caused by uneven heat input, such as incomplete penetration and slag inclusion, and improve the stability and reliability of the overall welding process. Taking a single Y-shaped groove as an example, one side has a slope and a blunt edge (slope side), and the other side has only a straight edge (blunt side). During welding, the thickness of the base material on the slope side gradually decreases, resulting in a shorter heat transfer path and faster heat dissipation on that side. The thickness of the base material on the blunt side is larger, and more heat accumulates, resulting in slower heat dissipation. This difference in heat conduction can cause the molten pool to shift towards the blunt side, increasing the risk of incomplete penetration or poor fusion. Therefore, the welding torch should be inclined at a certain angle towards the slope side.

[0050] The center line module calculates the weld center line based on the bevel polygon and the bevel normal. The polygon bisector line that bisects the area of the bevel polygon is found within the profile (polygon bisector line as Figure 2 the vertical dashed line in the middle), and the intersection point of the polygon bisector line and the first edge is marked as the center point (black solid point in Figure 2 ).

[0051] The tangent direction of the polygon bisector line is the same as the bevel normal, and the bevel polygon is divided according to the bevel normal. The ratio of the distance from the center point to the left edge point to the length of the first edge is set as the center line coefficient, denoted as , . The weld center line is ; that is, the calculation method of the weld center line is to multiply the vector from the left edge point to the right edge point by the center line coefficient and add the left edge point to obtain the weld center line. The polygon bisector line is , where is a fixed parameter (used to determine the profile), is a variable parameter (the point on the polygon bisector line in the profile is determined by ). The solution method of the weld center line is the solution method of the polygon bisector line, that is, the solution method of the center line coefficient . The polygon bisector line is solved using the bisection method. If the bevel polygon is left-right symmetric, the weld center line is .

[0052] The solution method of the weld center line includes:

[0053] Step 1, set the interval left end and interval right end of the center line coefficient value range, let the interval left end be 0, denoted as , and the interval right end be 1, denoted as ; calculate the total area of the bevel polygon, denoted as .

[0054] Step 2, calculate the average value of the left end and the right end of the interval, take the average value as the initial center line coefficient, calculate the intersection of the polygon bisector and the bevel polygon, calculate the left half area of the bevel polygon on the left side of the polygon bisector (here, "left" means the same as "left" in the left edge line, and the left half area of the polygon bisector is the shaded part on the left of the dotted line in the middle) denoted as Figure 2 ; the area of the polygon is calculated using the shoelace formula.

[0055] Step 3, if the absolute value of the difference between the left half area and half of the total area is less than a predetermined small amount , for example , denoted as , then output the initial center line coefficient of step 2 as the center line coefficient, and determine the weld center line according to the center line coefficient; otherwise (i.e. ), if the left half area is less than half of the total area, set the left end of the interval equal to the initial center line coefficient of step 2, and repeat step 2; if the left half area is greater than half of the total area, set the right end of the interval equal to the initial center line coefficient of step 2, and repeat step 2.

[0056] The shoelace formula is a method for calculating the area of a polygon by its vertex coordinates, which is suitable for any non-intersecting polygon; the shoelace formula is a prior art and will not be described here.

[0057] For a unit length of weld, the area of the bevel polygon determines the size of the molten pool, that is, the amount of filler metal; dividing the area of the bevel polygon in half can ensure the balance of the molten pool size on both sides; taking the point on the weld center line on the polygon bisector can increase the balance of heat input on both sides.

[0058] It is worth noting that the weld center line calculated in this embodiment is not the arc starting position of the welding torch head, and the displacement of the torch head relative to the weld center line should be determined according to the actual welding process requirements. The weld center line is the most important factor in determining the welding path of the welding torch. The actual placement position of the torch head is determined by the weld center line, the bevel direction, and the process parameters.

[0059] The path planning module combines the weld center lines of all positions of the weld on the welding object into a weld center line set, which is the welding path of the welding robot for the welding object.

[0060] ​The embodiment proposes a welding robot path automatic planning system, which successfully solves the problems of welding seam center line calculation and welding gun pointing determination in the groove profile for the complex curve welding seam with asymmetric groove in three-dimensional space, thereby effectively reducing the welding defects caused by uneven heat input and improving the stability and reliability of the overall welding process.

[0061] Specifically, the system realizes the calculation of the welding seam center line and the welding gun profile pointing by the following methods:

[0062] The Y-shaped welding seam is modeled as six welding contour lines with generalized parallel relationship between each other, including the left edge line A1, the right edge line A4, the left throat line A2, the right throat line A5, the left root line A3, and the right root line A6; the welding contour lines are fitted into contour line equations respectively; the tangent direction vector of the welding contour line is used as the profile normal vector to construct the groove polygon in the profile; the polygon bisector line that bisects the area of the groove polygon is solved in the profile by the bisection method, and the intersection point of the polygon bisector line and the first side is taken to determine the welding seam center line; the groove is rotated by a certain deflection angle in the profile, and then the welding gun profile pointing is obtained.

[0063] Compared with the prior art, the embodiment has the following advantages:

[0064] The traditional method is more suitable for simple or approximately symmetric welding seams, and it is difficult to accurately determine the "central axis" for complex curve welding seams or asymmetric groove design. The embodiment accurately calculates the welding seam center line by the polygon bisector line that bisects the area, which is more in line with the requirement of heat input balance of the welding process. The welding gun profile pointing is defined by the angle difference between the left and right slope lines, which effectively solves the problem of uneven heat input caused by heat conduction difference, thereby significantly reducing the occurrence of welding defects and improving the stability and reliability of the overall welding process. For the complex curve welding seam with asymmetric groove in three-dimensional space, the system provides a universal calculation method, which is obviously superior to the traditional welding path planning method based on simple geometry or symmetric assumption.

[0065] The places not mentioned in the application can be realized by using or referring to the existing technology.

[0066] The above is only an embodiment of the application and is not intended to limit the application. The application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the scope of the claims of the application.

Claims

1. A welding robot path automatic planning system, characterized by, The system comprises: a data input module for inputting weld contour line data of a Y-shaped weld; a contour line module for fitting the weld contour line into a contour line equation based on the weld contour line data; a bevel module for determining a land, a slope line and a bevel polygon of the bevel based on the contour line equation, and determining a bevel forward direction based on the land of the bevel; a pointing module for calculating a welding gun profile pointing direction based on the slope line and the bevel forward direction of the bevel; the calculation method of the welding gun profile pointing direction comprises: calculating an included angle one between the right slope line and the bevel forward direction; calculating an included angle two between the left slope line and the bevel forward direction; subtracting the included angle two from the included angle one and multiplying by a preset coefficient to obtain a deflection angle; determining a rotation direction of the bevel forward direction in the profile according to the deflection angle, if the deflection angle is positive, rotating clockwise, if the deflection angle is negative, rotating counterclockwise; taking an outer product of a tangent direction vector of the left edge line and the bevel forward direction as a rotation axis; rotating the bevel forward direction around the rotation axis by the deflection angle in the profile to obtain the welding gun profile pointing direction; a center line module for calculating a weld center line based on the bevel polygon and the bevel forward direction; the calculation method of the weld center line comprises: solving a center line coefficient based on the bevel polygon and the bevel forward direction; multiplying a vector from a left edge point to a right edge point by the center line coefficient and adding the left edge point to obtain the weld center line; the solving method of the center line coefficient comprises: Step 1, setting two parameters of an interval left end and an interval right end of a center line coefficient value range, setting the interval left end as 0 and the interval right end as 1; calculating a total area of the bevel polygon; Step 2, calculating an average value of the interval left end and the interval right end, taking the average value as an initial center line coefficient, calculating an intersection point of a polygon bisector and the bevel polygon, calculating a left half area of the bevel polygon on the left side of the polygon bisector; the area of the polygon is calculated using the shoelace formula; Step 3, if the absolute value of the difference between the left half area and half of the total area is less than a preset small amount, outputting the initial center line coefficient of Step 2 as the center line coefficient, and determining the weld center line according to the center line coefficient; otherwise, if the left half area is less than half of the total area, setting the interval left end equal to the initial center line coefficient of Step 2, repeating Step 2; if the left half area is greater than half of the total area, setting the interval right end equal to the center line coefficient of Step 2, repeating Step 2; a path planning module for combining the weld center lines of all positions of the weld of the welding object into a weld center line set, the weld center line set being a welding path of the welding robot for the welding object.

2. The welding robot path automatic planning system of claim 1, wherein, The weld contour line data is the spatial coordinates of the sampling points on the weld contour line; the weld contour line comprises a left edge line, a right edge line, a left throat line, a right throat line, a left root line and a right root line of a welding joint; The method for obtaining the weld contour line data comprises: capturing a weld image or scanning a workpiece surface through a 3D camera and a laser sensor, extracting weld feature points, classifying the weld feature points into points on the left edge line, the right edge line, the left throat line, the right throat line, the left root line and the right root line according to the positions of the weld feature points, recording the spatial coordinates of the weld feature points, and obtaining the weld contour line data.

3. The welding robot path automatic planning system of claim 1, wherein, The fitting method of the weld contour line comprises: taking any one of all the weld contour lines as a reference line, presetting a contour line equation of the reference line, and respectively presetting displacement vectors of the remaining weld contour lines relative to the reference line; removing abnormal points of the weld contour line data, fitting all the weld contour line data into corresponding contour line equations respectively by using a least square method, and obtaining contour line equations of the weld contour lines having a generalized parallel relationship between each other; the contour line equation is a segmented polynomial.

4. The welding robot path automatic planning system of claim 1, wherein, The calculation method of the bevel polygon comprises: taking points of the contour line equations in the section as vertices of the polygon to obtain the bevel polygon; The vertices of the bevel polygon are respectively a left edge point, a right edge point, a left throat point, a right throat point, a left root point and a right root point; and a line segment with the left edge point and the right edge point as end points is defined as a first side of the bevel polygon; The calculation method of the land comprises: subtracting the left throat point from the left root point to obtain a left land; and subtracting the right throat point from the right root point to obtain a right land; The calculation method of the slope line comprises: subtracting the left throat point from the left edge point to obtain a left slope line; and subtracting the right throat point from the right edge point to obtain a right slope line; The calculation method of the bevel positive direction comprises: calculating a vector sum of the left land and the right land, and performing unitization on the vector sum to obtain the bevel positive direction.

5. The welding robot path automatic planning system of claim 1, wherein, The polygon bisector is a straight line bisecting the area of the bevel polygon in the section; and a tangent direction of the polygon bisector is the same as the bevel positive direction.

6. The welding robot path automatic planning system of claim 3, wherein, The generalized parallel relationship is that a line segment with a fixed length moves in a direction perpendicular to itself in space, and two spatial curves are formed by the trajectories of the two end points of the line segment.

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