Robot flexible welding path planning method for transmission tower feet

Abstract

The present invention discloses a robot flexible welding path planning method for transmission tower legs, comprising the following steps: Step 1: Placing the leg to be welded at any position on a turntable plane; Step 2: Obtaining and processing surface point cloud information of the leg to be welded to obtain a point cloud model and weld seam information of the leg to be welded; Step 3: Applying a turntable rotation scheme, generating candidate intervals for the turntable target angle based on a welding position model and a turntable angle adjustment strategy, and determining the turntable target angle by merging common intervals; Step 4: Combining a sampling space optimization method based on the geometric characteristics of the leg with a path planning algorithm to complete welding path planning; Step 5: Sending welding path parameters to a robot control cabinet to execute welding. The present invention solves the problems of path redundancy, collaborative positioning difficulties, and geometric occlusion in the prior art by collaboratively planning the welding path between the turntable and the robot. The method is intelligent, instruction-free, efficient, and highly flexible.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot flexible welding, and specifically relates to a robot flexible welding path planning method for a transmission tower foot. Background Art

[0002] Transmission towers are crucial infrastructure in power systems, used for high-voltage, extra-high-voltage, and ultra-high-voltage direct current (DC) and alternating current (AC) transmission. Transmission tower legs, crucial structural components connecting the tower to the foundation, often require custom designs due to various factors, such as topography and climate. Consequently, tower legs are often non-standard components produced in small batches and with varying specifications. The manufacturing process for these legs consists of three main stages: cutting and blanking, spot welding, and overall welding. Currently, cutting and blanking are largely automated, while spot welding and overall welding rely primarily on manual labor. Due to the fluctuating specifications and small production batches of transmission tower legs, it is difficult to develop a standardized welding procedure. Whenever the leg specifications change, operators spend a significant amount of time on teaching and programming, resulting in low production efficiency, inconsistent weld quality, and excessively high labor costs. Therefore, a flexible robotic welding path planning method is urgently needed for transmission tower legs to improve the intelligence and automation of the overall welding process and accelerate the production of transmission tower legs.

[0003] Robot flexible welding is an advanced welding technology that uses multi-axis industrial robots for operation. It can flexibly configure corresponding data processing algorithms according to different welding processes and requirements, extract processing information and control the robot to complete a series of welding tasks. This technology can significantly improve the automation level and efficiency of welding operations, and achieve efficient, high-quality and high-precision automatic welding of workpieces. Relevant research on robot flexible welding technology mainly focuses on weld starting position guidance, weld extraction, weld tracking, welding pool monitoring and welding path planning. Among them, welding path planning technology is particularly critical, requiring the robot to quickly plan the movement path of the welding gun based on the identified workpiece information and weld information. In the welding path planning problem of the transmission tower foot, there are still several key difficulties:

[0004] (1) The geometric structure of the tower foot will partially block the robot welding. During the welding process, there may be situations where the weld position is not conducive to the robot's end welding gun reaching it. Therefore, the turntable needs to be rotated to adjust the workpiece position, and the positioning coordination problem between the turntable and the robot needs to be solved.

[0005] (2) In the robotic arm path planning problem, sampling-based motion planning algorithms are often used to find a collision-free path from the robot's initial state to the target state, but the intermediate path positions of the collision-free path are not constrained, which may lead to redundant or inefficient paths.

[0006] (3) In the path planning problem of a six-axis robotic arm, the path planning algorithm usually searches for solutions in the robot joint space, while the information collected by the sensor comes from the Cartesian space. Therefore, how to reasonably use the effective information in the Cartesian space to optimize the path planning algorithm is an urgent problem to be solved.

[0007] Transmission towers are crucial infrastructure in power systems, used for high-voltage, extra-high-voltage, and ultra-high-voltage direct current (DC) and alternating current (AC) transmission. Transmission tower legs, crucial structural components connecting the tower to the foundation, often require custom designs due to various factors, such as topography and climate. Consequently, tower legs are often non-standard components produced in small batches and with varying specifications. The manufacturing process for these legs consists of three main stages: cutting and blanking, spot welding, and overall welding. Currently, cutting and blanking are largely automated, while spot welding and overall welding rely primarily on manual labor. Due to the fluctuating specifications and small production batches of transmission tower legs, it is difficult to develop a standardized welding procedure. Whenever the leg specifications change, operators spend a significant amount of time on teaching and programming, resulting in low production efficiency, inconsistent weld quality, and excessively high labor costs. Therefore, a flexible robotic welding path planning method is urgently needed for transmission tower legs to improve the intelligence and automation of the overall welding process and accelerate the production of transmission tower legs.

[0008] Robot flexible welding is an advanced welding technology that uses multi-axis industrial robots for operation. It can flexibly configure corresponding data processing algorithms according to different welding processes and requirements, extract processing information and control the robot to complete a series of welding tasks. This technology can significantly improve the automation level and efficiency of welding operations, and achieve efficient, high-quality and high-precision automatic welding of workpieces. Relevant research on robot flexible welding technology mainly focuses on weld starting position guidance, weld extraction, weld tracking, welding pool monitoring and welding path planning. Among them, welding path planning technology is particularly critical, requiring the robot to quickly plan the movement path of the welding gun based on the identified workpiece information and weld information. In the welding path planning problem of the transmission tower foot, there are still several key difficulties:

[0009] (1) The geometric structure of the tower foot will partially block the robot welding. During the welding process, there may be situations where the weld position is not conducive to the robot's end welding gun reaching it. Therefore, the turntable needs to be rotated to adjust the workpiece position, and the positioning coordination problem between the turntable and the robot needs to be solved.

[0010] (2) In the robotic arm path planning problem, sampling-based motion planning algorithms are often used to find a collision-free path from the robot's initial state to the target state, but the intermediate path positions of the collision-free path are not constrained, which may lead to redundant or inefficient paths.

[0011] (3) In the path planning problem of a six-axis robotic arm, the path planning algorithm usually searches for solutions in the robot joint space, while the information collected by the sensor comes from the Cartesian space. Therefore, how to reasonably use the effective information in the Cartesian space to optimize the path planning algorithm is an urgent problem to be solved. Summary of the Invention

[0012] In view of this, the purpose of the present invention is to provide a robot flexible welding path planning method for the tower foot of a transmission tower. By cooperating with a turntable and a robot to plan the welding path, the problems of path redundancy, collaborative positioning difficulties and geometric occlusion existing in the prior art are solved, and the method has the characteristics of intelligence, no teaching required, high efficiency and high flexibility.

[0013] In order to achieve the above object, the present invention provides the following technical solutions:

[0014] A robot flexible welding path planning method for transmission tower legs comprises the following steps:

[0015] Step 1: Place the tower foot to be welded at any position on the turntable plane;

[0016] Step 2: Obtain and process the surface point cloud information of the tower foot to be welded to obtain the point cloud model and weld information of the tower foot to be welded;

[0017] Step 3: Apply the turntable rotation plan, generate candidate turntable target angle intervals based on the welding position model and turntable angle adjustment strategy, and determine the turntable target angle by merging common intervals;

[0018] The turntable rotation scheme determines the target turntable angle by calculating the target angle candidate intervals for each weld and obtaining the intersection of the target angle candidate intervals according to the welding sequence;

[0019] The welding position model includes a weld coordinate system and an inclination angle , deflection angle and spin angle The three key positioning parameters are used to describe the relative position of the weld and the robot coordinate system;

[0020] Step 4: Combine the sampling space optimization method based on the geometric characteristics of the tower foot with the path planning algorithm to complete the welding path planning;

[0021] The sampling space optimization method improves the path planning efficiency by defining elliptical arc interpolation points in a semi-open interval and combining it with inverse kinematics mapping.

[0022] Step 5: Send the welding path parameters to the robot control cabinet to perform welding.

[0023] Furthermore, the turntable rotation scheme is:

[0024] According to the welding position model, the weld coordinate system and three key positioning parameters of each weld are calculated respectively;

[0025] According to the turntable angle adjustment strategy and combined with the welding position model of each weld, the target angle candidate interval of each weld is calculated respectively;

[0026] Traverse backward in the welding order of the welds, calculate the intersection of the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent welds, and retain the valid intersection as the new candidate interval;

[0027] If there is no intersection between the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent weld, the cumulative traversed weld numbers are recorded and the current traversal is stopped. The next unprocessed weld is jumped to in the welding order of the welds; the intersection with the target angle candidate interval of the subsequent weld is continued to be searched until the target angle candidate intervals of all welds are traversed;

[0028] The midpoint of the new candidate interval is taken as the target turntable angle.

[0029] Furthermore, the weld coordinate system The definitions include:

[0030] The origin of the coordinate system is located at the starting point of the weld. The starting point of the weld is the end point closer to the center of the turntable among the two end points of the weld, and the end point of the weld is the other end point of the weld.

[0031] The axis direction is from the weld start point to the weld end point;

[0032] The axis is determined by adding the outward normal vectors of the two planes forming the weld;

[0033] The axes are determined using the right-hand rule.

[0034] Further, define the robot coordinate system , then the three key positioning parameters are defined as:

[0035] Tilt angle : Axis and The angle between the planes, and: if Axis unit vector and If the dot product of the axis unit vector is greater than 0, then the tilt angle is positive, otherwise it is negative;

[0036] Deflection angle : Axis Projection on the plane and The angular deviation between the axes is in the direction of the Right-hand rule for axial rotation;

[0037] Spin angle : Axis The projection of the axis on the vertical plane is The angular deviation of the axis is in the direction of the Right-hand rule for axial rotation.

[0038] Furthermore, the turntable angle adjustment strategy includes:

[0039] According to the tilt angle Determine the weld type and adjust the turntable angle range;

[0040] According to the spin angle Classify welding position areas and limit deflection angles interval;

[0041] The geometric characteristics of the tower base are combined to further constrain the corner range and avoid obstruction by non-horizontal parent material plates.

[0042] Furthermore, when the tilt angle for When the weld type is vertical weld, adjust the turntable angle so that Axis and The angle between the axes is ; When the tilt angle for When , the weld type is horizontal weld and the turntable angle is not adjusted.

[0043] Furthermore, if the spin angle , it is defined as the left side weld, then the right half area will have its own shielding problem, welding is carried out in the left half area facing the tower foot, and the turntable angle is adjusted so that the deflection angle lie in On the contrary, if the spin angle , defined as the right side weld, the right half area will have its own shielding problem, so the welding is carried out in the left half area facing the tower foot, and the turntable angle is adjusted so that the deflection angle lie in .

[0044] Furthermore, for the left weld, the left half of the weld is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point as the weld. The turntable angle is adjusted so that the deflection angle lie in For the right weld, the right half of the weld is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point. Adjust the turntable angle so that the deflection angle lie in ;in: It is the angle between the non-horizontal base plate of the left weld or the right weld and the non-horizontal base plate of another horizontal weld with the same weld starting point.

[0045] Furthermore, the sampling space optimization method specifically includes:

[0046] Define safety points A, B, and the vertical median line L; where point A is a safety point about 5-20 mm in front of the next weld starting point, and its coordinate value relative to the robot coordinate system is Point B is a safety point about 5-20mm in front of the end point of the previous weld. Its coordinate value relative to the robot coordinate system is ; Line L is the perpendicular bisector of line segment AB in the vertical direction;

[0047] The semi-ellipse parameters are determined based on the intersection of the semi-open interval and the non-horizontal base plate; the semi-open interval has three boundaries, the first boundary is the line segment AB, the second boundary is the vertical upward ray starting from point A, and the third boundary is the vertical upward ray starting from point B;

[0048] Interpolate points along the elliptical arc AB and map them to the robot's joint space through inverse kinematics to increase the neighborhood sampling frequency.

[0049] Furthermore, the method for determining the parameters of the semi-ellipse is as follows: the semi-open interval intersects the non-horizontal base plate, and the point C in the intersecting contour that is farthest from the line segment AB and the line L is found; point C is defined as a point on the ellipse, and the coordinate value is The ellipse vertices are points A and B, the ellipse center O is the midpoint of line segment AB, and the coordinate value of the ellipse center relative to the robot coordinate system is , then the distance between line segment OC and line segment AB is:

[0050]

[0051]

[0052] like , then line segment AB is the minor axis of the ellipse, ;like , then line segment AB is the major axis of the ellipse, ; The equation of the ellipse can be solved by combining the following equations, and the parameters of the semi-ellipse can be obtained:

[0053]

[0054]

[0055] in: is the semi-major axis of the ellipse; is the minor semi-axis of the ellipse; is the semi-focal length of the ellipse.

[0056] The beneficial effects of the present invention are:

[0057] The present invention provides a robot flexible welding path planning method for transmission tower legs, which has the following technical effects:

[0058] A welding position model for the tower foot of a transmission tower was proposed. This model can fully describe the position of the tower foot workpiece in the robot coordinate system with six degrees of freedom and determine the relative position relationship between each weld and the robot coordinate system.

[0059] A turntable angle adjustment strategy was proposed. Based on the welding position model of the transmission tower foot, a method for obtaining the candidate interval of the turntable target angle was specified. This solved the problem of partial occlusion of the robot welding caused by the geometric structure of the transmission tower foot.

[0060] A turntable rotation scheme was proposed, resulting in a series of target turntable angles that could rotate the workpiece to a position that was conducive to robot welding. This solved the positioning coordination problem between the turntable and the robot. Furthermore, the turntable rotation scheme minimized the number of turntable rotations, improving overall efficiency.

[0061] A sampling space optimization method based on the geometric characteristics of the tower base is proposed. Guidance information from the Cartesian space is introduced when sampling the path planning algorithm, which reduces the probability of generating redundant or inefficient paths and effectively improves the quality and efficiency of the path planning algorithm solution.

[0062] In summary, the present invention is a method for planning a flexible welding path for a robot used for the legs of a transmission tower. By coordinating the turntable and the robot to plan the welding path, the problems of path redundancy, collaborative positioning difficulties, and geometric occlusion existing in the prior art are solved. The method also has the characteristics of intelligence, no need for teaching, high efficiency, and high flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0064] Figure 1 This is a structural diagram of the automatic welding system for transmission tower feet;

[0065] Figure 2 This is a flow chart of a method for planning a robot flexible welding path for a transmission tower foot according to the present invention;

[0066] Figure 3 A flow chart of the turntable rotation scheme;

[0067] Figure 4 This is a schematic diagram of the welding position model of the transmission tower foot;

[0068] Figure 5 Schematic diagram of the sampling space optimization method.

[0069] Description of reference numerals:

[0070] 1- Host computer; 2- Welding power supply; 3- Robot control cabinet; 4- Welding robot; 5- Turntable; 6- Tower foot to be welded; 7- Turntable bracket; 8- Scanning frame; 9- 3D structured light camera. DETAILED DESCRIPTION

[0071] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0072] like Figure 1 As shown, the automatic welding system for transmission tower legs includes a host computer 1, a welding power supply 2, a robot control cabinet 3, a welding robot 4, a turntable 5, a tower leg to be welded 6, a turntable bracket 7, a scanning frame 8, and a 3D structured light camera 9. The host computer 1 receives point cloud information from the surface of the tower leg 6 captured by the 3D structured light camera 9, performs point cloud processing, and completes weld seam extraction and welding path planning for the welding robot 4. The welding power supply 2 provides power to the robot control cabinet 3, the welding robot 4, the turntable 5, and the 3D structured light camera 9. The robot control cabinet 3 receives welding path, trajectory parameters, and welding process parameters from the host computer 1 to control the welding process of the welding robot 4 and the mechanical movement of the turntable 5. The turntable 5 is fixed by the turntable bracket 7, and the tower leg 6 to be welded is placed on the turntable 5. The height and angle of the camera can be adjusted by adjusting the position of the hinge on the scanning frame 8.

[0073] The following describes a specific implementation of the robot flexible welding path planning method for the transmission tower foot of the present invention in conjunction with the transmission tower foot automatic welding system.

[0074] like Figure 2 As shown, the robot flexible welding path planning method for the transmission tower foot of this embodiment includes the following steps.

[0075] Step 1: Place the tower foot 6 to be welded at any position on the turntable 5 plane of the transmission tower foot automatic welding system.

[0076] Step 2: The surface point cloud information of the tower foot 6 to be welded is obtained by the automatic welding system for the transmission tower foot and processed to obtain the point cloud model and weld information of the tower foot 6 to be welded.

[0077] Step 3: Apply the turntable 5 rotation scheme, generate the candidate intervals of the turntable 5 target angle based on the welding position model and the turntable 5 angle adjustment strategy, and determine the turntable 5 target angle by merging the common intervals to solve the collaborative positioning problem between the welding robot 4 and the turntable 5.

[0078] (1) Rotation scheme of turntable 5.

[0079] The turntable 5 rotation scheme calculates the target angle candidate intervals for each weld and obtains the intersection of the target angle candidate intervals according to the welding sequence to determine the target turntable 5 angle.

[0080] like Figure 3 As shown, in this embodiment, the rotation scheme of the turntable 5 includes:

[0081] According to the welding position model, the weld coordinate system and three key positioning parameters of each weld are calculated respectively;

[0082] According to the rotation angle adjustment strategy of turntable 5, the target rotation angle candidate interval of each weld is calculated in combination with the welding position model of each weld;

[0083] Traverse backward in the welding order of the welds, calculate the intersection of the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent welds, and retain the valid intersection as the new candidate interval;

[0084] If there is no intersection between the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent weld, the cumulative traversed weld numbers are recorded and the current traversal is stopped. The next unprocessed weld is jumped to in the welding order of the welds; the intersection with the target angle candidate interval of the subsequent weld is continued to be searched until the target angle candidate intervals of all welds are traversed;

[0085] The midpoint of the new candidate interval is taken as the target turntable 5 corner.

[0086] (2) Welding position model.

[0087] The welding position model includes the weld coordinate system and the tilt angle , deflection angle and spin angle The three key positioning parameters are used to describe the relative position of the weld and the robot coordinate system.

[0088] like Figure 4 As shown, in this embodiment, the weld coordinate system The definitions include:

[0089] The origin of the coordinate system is located at the starting point of the weld. The starting point of the weld is the end point of the weld that is closer to the center of the turntable 5, and the end point of the weld is the other end point of the weld.

[0090] The axis direction is from the weld start point to the weld end point;

[0091] The axis is determined by adding the outward normal vectors of the two planes forming the weld, and The axis is vertical and points outward;

[0092] The axes are determined using the right-hand rule.

[0093] Specifically, obtain the conditions that meet The axis method includes: respectively calculating the outward normal vectors of the two planes constituting the weld, the direction of the outward normal vector is the plane on the other side of the base plate where the plane is located pointing to the current plane; adding the outward normal vectors of the two planes constituting the weld to obtain the weld coordinate system corresponding to the weld axis.

[0094] In this embodiment, the robot coordinate system is defined as , then the three key positioning parameters are defined as:

[0095] Tilt angle : Axis and The angle between the planes, and: if Axis unit vector and If the dot product of the axis unit vector is greater than 0, then the tilt angle is positive, otherwise it is negative;

[0096] Deflection angle : Axis Projection on the plane and The angular deviation between the axes is in the direction of the Right-hand rule for axial rotation;

[0097] Spin angle : Axis The projection of the axis on the vertical plane is The angular deviation of the axis is in the direction of the Right-hand rule for axial rotation.

[0098] (3) Turntable 5 corner adjustment strategy.

[0099] In this embodiment, the angle adjustment strategy of the turntable 5 includes the following contents.

[0100] Set the robot coordinate system Axis facing turntable 5, robot coordinate system The axis is vertically upward.

[0101] According to the tilt angle Determine the weld type and adjust the turntable 5 angle range. Specifically, when the tilt angle for When the weld type is vertical weld, adjust the turntable 5 angle to make Axis and The angle between the axes is ; When the tilt angle for When the weld type is horizontal weld, the turntable 5 angle is not adjusted.

[0102] According to the spin angle Classify welding position areas and limit deflection angles Specifically, if the spin angle , it is defined as the left weld, then the right half area will have its own shielding problem, that is, the non-horizontal base material plate forming this weld will block the welding robot 4, so welding must be carried out in the left half area facing the tower foot, and the turntable 5 angle is adjusted so that the deflection angle lie in On the contrary, if the spin angle , defined as the right side weld, the right half area will have its own shielding problem, so the welding must be carried out in the left half area facing the tower foot, and the turntable 5 angle is adjusted so that the deflection angle lie in .

[0103] The geometric characteristics of the tower base are combined to further constrain the corner range and avoid obstruction by non-horizontal parent material plates.

[0104] Furthermore, for the left side weld, when it is in the left half area facing it, its left half area is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point as the weld, so it is necessary to adjust the rotation angle of the turntable 5 so that the deflection angle lie in For the right side weld, when it is in the right half area facing it, its right half area is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point as the weld, so it is necessary to adjust the turntable 5 angle so that the deflection angle lie in ;in: It is the angle between the non-horizontal base plate of the left weld or the right weld and the non-horizontal base plate of another horizontal weld with the same weld starting point.

[0105] Step 4: Combine the sampling space optimization method based on the geometric characteristics of the tower foot with the path planning algorithm to complete the welding path planning.

[0106] Specifically, the sampling space optimization method improves the efficiency of path planning by defining elliptical arc interpolation points in a semi-open interval and combining it with inverse kinematics mapping. Figure 5 As shown, in this embodiment, the sampling space optimization method specifically includes the following contents.

[0107] Define safety points A, B, and the vertical median line L. Point A is a safety point about 5-20 mm in front of the next weld starting point, and its coordinate value relative to the robot coordinate system is Point B is a safety point about 5-20mm in front of the end point of the previous weld. Its coordinate value relative to the robot coordinate system is ; Straight line L is the vertical bisector of line segment AB.

[0108] The semi-ellipse parameters are determined based on the intersection of the semi-open interval and the non-horizontal base plate. The semi-open interval has three boundaries: boundary one is line segment AB, boundary two is a ray pointing vertically upward from point A, and boundary three is a ray pointing vertically upward from point B.

[0109] Interpolate points along the elliptical arc AB and map them to the robot's joint space using inverse kinematics using the Jacobian matrix. During the sampling-based algorithm, increase the sampling frequency of the interpolated points within the robot's joint space to improve the quality and efficiency of the path planning solution.

[0110] Specifically, in this embodiment, the method for determining the parameters of the semi-ellipse is as follows: the semi-open interval intersects the non-horizontal base plate, and the point farthest from the line segment AB in the intersecting contour is found. If there are multiple points, the point farthest from the line L is further selected and set as point C. Point C is defined as a point on the ellipse, and its coordinate value is The ellipse vertices are points A and B, the ellipse center O is the midpoint of line segment AB, and the coordinate value of the ellipse center relative to the robot coordinate system is , then the distance between line segment OC and line segment AB is:

[0111]

[0112]

[0113] like , then line segment AB is the minor axis of the ellipse, ;like , then line segment AB is the major axis of the ellipse, ; The equation of the ellipse can be solved by combining the following equations, and the parameters of the semi-ellipse can be obtained:

[0114]

[0115]

[0116] in: is the semi-major axis of the ellipse; is the minor semi-axis of the ellipse; is the semi-focal length of the ellipse.

[0117] Step 5: Send the welding path parameters to the robot control cabinet 3 to guide the welding robot 4 to perform welding.

[0118] The above-described embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A robot flexible welding path planning method for transmission tower legs, characterized by: The steps include: Step 1: Place the tower foot to be welded at any position on the turntable plane; Step 2: Obtain and process the surface point cloud information of the tower foot to be welded to obtain the point cloud model and weld information of the tower foot to be welded; Step 3: Apply the turntable rotation plan, generate candidate turntable target angle intervals based on the welding position model and turntable angle adjustment strategy, and determine the turntable target angle by merging common intervals; The turntable rotation scheme determines the target turntable angle by calculating the target angle candidate intervals for each weld and obtaining the intersection of the target angle candidate intervals according to the welding sequence; The welding position model includes a weld coordinate system and an inclination angle , deflection angle and spin angle The three key positioning parameters are used to describe the relative position of the weld and the robot coordinate system; Step 4: Combine the sampling space optimization method based on the geometric characteristics of the tower foot with the path planning algorithm to complete the welding path planning; The sampling space optimization method improves the path planning efficiency by defining elliptical arc interpolation points in a semi-open interval and combining it with inverse kinematics mapping; Step 5: Send the welding path parameters to the robot control cabinet to perform welding.

2. The method for planning a robot flexible welding path for a transmission tower foot according to claim 1, characterized in that: The turntable rotation scheme is: According to the welding position model, the weld coordinate system and three key positioning parameters of each weld are calculated respectively; According to the turntable angle adjustment strategy and combined with the welding position model of each weld, the target angle candidate interval of each weld is calculated respectively; Traverse backward in the welding order of the welds, calculate the intersection of the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent welds, and retain the valid intersection as the new candidate interval; If there is no intersection between the target angle candidate interval of the current weld and the target angle candidate interval of the subsequent weld, the cumulative traversed weld numbers are recorded and the current traversal is stopped. The next unprocessed weld is jumped to in the welding order of the welds; the intersection with the target angle candidate interval of the subsequent weld is continued to be searched until the target angle candidate intervals of all welds are traversed; The midpoint of the new candidate interval is taken as the target turntable angle.

3. The method for planning a robot flexible welding path for a transmission tower foot according to claim 1 or 2, characterized in that: The weld coordinate system The definitions include: The origin of the coordinate system is located at the starting point of the weld. The starting point of the weld is the end point closer to the center of the turntable among the two end points of the weld, and the end point of the weld is the other end point of the weld. The axis direction is from the weld start point to the weld end point; The axis is determined by adding the outward normal vectors of the two planes forming the weld; The axes are determined using the right-hand rule.

4. The method for planning a robot flexible welding path for a transmission tower foot according to claim 3, characterized in that: Define the robot coordinate system , then the three key positioning parameters are defined as: Tilt angle : Axis and The angle between the planes, and: if Axis unit vector and If the dot product of the axis unit vector is greater than 0, then the tilt angle is positive, otherwise it is negative; Deflection angle : Axis Projection on the plane and The angular deviation between the axes is in the direction of the Right-hand rule for axial rotation; Spin angle : Axis The projection of the axis on the vertical plane is The angular deviation of the axis is in the direction of the Right-hand rule for axial rotation.

5. The method for planning a robot flexible welding path for a transmission tower foot according to claim 4, characterized in that: The turntable angle adjustment strategy includes: According to the tilt angle Determine the weld type and adjust the turntable angle range; According to the spin angle Classify welding position areas and limit deflection angles interval; The geometric characteristics of the tower base are combined to further constrain the corner range and avoid obstruction by non-horizontal parent material plates.

6. The method for planning a robot flexible welding path for a transmission tower foot according to claim 5, characterized in that: When the tilt angle for When the weld type is vertical weld, adjust the turntable angle so that Axis and The angle between the axes is ; When the tilt angle for When , the weld type is horizontal weld and the turntable angle is not adjusted.

7. The method for planning a robot flexible welding path for a transmission tower foot according to claim 5, characterized in that: If the spin angle , it is defined as the left side weld, then the right half area will have its own shielding problem, welding is carried out in the left half area facing the tower foot, and the turntable angle is adjusted so that the deflection angle lie in On the contrary, if the spin angle , defined as the right side weld, the right half area will have its own shielding problem, so the welding is carried out in the left half area facing the tower foot, and the turntable angle is adjusted so that the deflection angle lie in .

8. The method for planning a robot flexible welding path for a transmission tower foot according to claim 7, characterized in that: For the left weld, the left half of the weld is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point. Adjust the turntable angle so that the deflection angle lie in For the right weld, the right half of the weld is blocked by the non-horizontal base plate of another horizontal weld with the same weld starting point. Adjust the turntable angle so that the deflection angle lie in ;in: It is the angle between the non-horizontal base plate of the left weld or the right weld and the non-horizontal base plate of another horizontal weld with the same weld starting point.

9. The method for planning a robot flexible welding path for a transmission tower foot according to claim 1, characterized in that: The sampling space optimization method specifically includes: Define safety points A, B, and the vertical median line L; where point A is a safety point about 5-20 mm in front of the next weld starting point, and its coordinate value relative to the robot coordinate system is Point B is a safety point about 5-20mm in front of the end point of the previous weld. Its coordinate value relative to the robot coordinate system is ; Line L is the perpendicular bisector of line segment AB in the vertical direction; The semi-ellipse parameters are determined based on the intersection of the semi-open interval and the non-horizontal base plate; the semi-open interval has three boundaries, the first boundary is the line segment AB, the second boundary is the vertical upward ray starting from point A, and the third boundary is the vertical upward ray starting from point B; Interpolate points along the elliptical arc AB and map them to the robot's joint space through inverse kinematics to increase the neighborhood sampling frequency.

10. The method for planning a robot flexible welding path for a transmission tower foot according to claim 9, characterized in that: The method for determining the parameters of the semi-ellipse is as follows: the semi-open interval intersects the non-horizontal base plate, and finds the point C in the intersecting contour that is farthest from the line segment AB and the line L; point C is defined as a point on the ellipse, and its coordinate value is The ellipse vertices are points A and B, the ellipse center O is the midpoint of line segment AB, and the coordinate value of the ellipse center relative to the robot coordinate system is , then the distance between line segment OC and line segment AB is: like , then line segment AB is the minor axis of the ellipse, ;like , then line segment AB is the major axis of the ellipse, ; The equation of the ellipse can be solved by combining the following equations, and the parameters of the semi-ellipse can be obtained: in: is the semi-major axis of the ellipse; is the minor semi-axis of the ellipse; is the semi-focal length of the ellipse.

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