Method for generating swing welding track for any welding line path
By calibrating the coordinate system of the robotic arm tool and arc length planning, the interpolation point matrix is generated, combined with the swing matrix and cubic spline interpolation, the problem of difficulty in generating complex paths and ensuring uniform welding speed in traditional methods is solved, and high-quality swing welding trajectory generation is achieved and welding effect.
Patent Information
- Application Number
- CN202411607939.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-01-10
AI Technical Summary
The traditional method of generating pendulum welding trajectory is complicated and difficult to generate complex paths, and it is impossible to ensure uniform movement during welding, resulting in poor welding quality.
By calibrating the coordinate system of the robotic arm tool, the arc length is used to trajectory planning to generate interpolation points, which is converted into matrix form, and the right-multiple swing matrix generates a pendulum welding trajectory matrix, and speed planning is performed by combining cubic spline interpolation.
The pendulum welding of any trajectory is realized, the trajectory generation model is simplified, the uniform movement of the entire welding process is ensured, and the welding quality is improved.
Smart Images
Figure CN119282551A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of methods for generating a weaving welding trajectory, and in particular to a method for generating a weaving welding trajectory for an arbitrary weld path. Background Art
[0002] When performing swing welding, the welding robot uses a specific motion pattern to achieve uniform distribution of welds and high-quality welding results. Swing welding is a common welding technology that is suitable for welds that need to cover a larger width or thickness. Swing welding is a welding robot that controls the movement trajectory of the welding gun so that it swings horizontally across the weld. The swing path can be a straight line, a sine wave, a zigzag, or other complex shapes; the robot needs to accurately control the swing speed of the welding gun and the welding speed to ensure the quality and consistency of the weld.
[0003] The traditional method of generating the weaving welding trajectory requires the establishment of multiple coordinate systems for coordinate transformation; this method is not only complicated, but can only generate weaving welding trajectories for some simple paths such as straight lines and arcs. Especially for some complex trajectories such as intersecting lines, the derivation process is extremely cumbersome. And some paths generated by the heat deformation of the workpiece, the traditional method is powerless. Moreover, the traditional weaving welding simply makes the speed component along the direction of the weld uniform. The speed of the trajectory cannot guarantee a uniform speed during welding, and it is generally periodic fluctuations, which can easily cause accumulation during welding. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention aims to provide a method for generating a weaving welding trajectory for an arbitrary weld path, which can solve the existing problems.
[0005] In order to achieve the above object, the technical solution of the present invention is as follows:
[0006] The present invention is realized by the following technical solution: a method for generating a weaving welding trajectory for an arbitrary weld path, comprising the following steps:
[0007] Step 1: Calibrate the robot tool coordinate system to determine the swing direction;
[0008] Step 2: In the calibrated coordinate system, using arc length to perform trajectory planning to generate a corresponding plurality of interpolation points; converting the interpolation points into a matrix form to form an interpolation point matrix;
[0009] Step 3: The interpolation point matrix is right-multiplied by the swing matrix in sequence to generate a matrix corresponding to the swing welding trajectory, and converted into the interpolation point coordinate form;
[0010] Step 4: Based on the coordinates of the interpolation points in the trajectory and the arc length of the welding trajectory, use cubic spline interpolation to determine the relationship between the two and re-plan the speed.
[0011] Furthermore, the calibration of the robot tool coordinate system to determine the swing direction includes:
[0012] Calibrate the TCP coordinate system of the robot arm, where the z direction is the direction of the welding gun; the x axis is the direction of the welding feed. During point teaching, ensure that the x direction of the TCP is along the tangent direction of the weld; y is the swing direction calculated internally by the algorithm. The direction of the swing welding plane can be adjusted by adjusting the z axis direction.
[0013] Furthermore, in the calibrated coordinate system, arc length is used to perform trajectory planning to generate corresponding interpolation points; the interpolation points are converted into a matrix form to form an interpolation point matrix; including
[0014] When performing trajectory planning, a series of interpolation points P (x, y, z, rx, ry, rz) are generated; these interpolation points are generated using speed planning with an arc length of s; for each interpolation point, (x, y, z) can be used to represent the origin of the TCP coordinate system at this time, and (rx, ry, rz) can be converted into a rotation matrix R = [n, s, a] to represent the direction of the three coordinate axes of the TCP coordinate system; these interpolation points are all converted into a series of matrices:
[0015]
[0016] Furthermore, the interpolation point matrix is right-multiplied by the swing matrix in sequence to generate a matrix corresponding to the swing welding trajectory, and converted into the interpolation point coordinate form, including
[0017] Multiply the right side by a matrix Tswing. This right-multiplied matrix represents the homogeneous transformation matrix relative to the TCP coordinate system, which is used to represent the swing. Generate a new swing welding path. The corresponding points at this time are:
[0018]
[0019] Furthermore, the matrix Tswing is a swing matrix, and its rotation matrix part is a unit matrix, so that the swing along the three coordinate axes of TCP can be achieved.
[0020] Furthermore, the trajectory is planned as a circular trajectory, and the homogeneous transformation matrix includes a homogeneous transformation matrix that characterizes the fold line swing:
[0021]
[0022] Homogeneous transformation matrix of sinusoidal oscillation:
[0023]
[0024] The homogeneous transformation matrix of the spiral swing is as follows:
[0025]
[0026] Where a is the swing welding width, w is the swing welding spacing, and s is the trajectory arc length corresponding to the interpolation point at this time.
[0027] A device for generating a weaving welding trajectory for any weld path comprises a processor and a memory; the memory is used to store a program; the processor executes the program to implement any of the above methods.
[0028] A computer-readable storage medium, characterized in that: the storage medium stores a program, and the program is executed by a processor to implement any of the above methods.
[0029] Compared with the prior art, the beneficial effects of the present invention include:
[0030] The present invention uses arc length s for trajectory planning, generates a corresponding series of interpolation points, and converts these interpolation points into a matrix form. These interpolation point matrices are right-multiplied by the swing matrix in turn to generate a matrix corresponding to the swing welding trajectory, and then converted into the interpolation point coordinate form. The relationship between the swing welding trajectory coordinates and the arc length of the swing welding trajectory is obtained by cubic spline interpolation, and speed planning is performed again. The method of the present invention can realize the swing welding of any trajectory, and is no longer limited to simple straight lines and arcs; it abandons the cumbersome coordinate system conversion, and generates a swing welding trajectory generation model very concisely; it can achieve a uniform speed throughout the swing welding trajectory. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:
[0032] Figure 1 A schematic flow chart of a method for generating a weaving welding trajectory for an arbitrary weld path according to the present invention;
[0033] Figure 2 : is a schematic diagram of a broken line pendulum trajectory in an implementation example of the present invention;
[0034] Figure 3 Schematic diagram of the trajectory of the sine pendulum in the implementation case of the present invention;
[0035] Figure 4 Schematic diagram of the spiral pendulum trajectory in the implementation example of the present invention. DETAILED DESCRIPTION
[0036] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.
[0037] The traditional method of generating a pendulum welding path is not only complicated, but can only generate pendulum welding trajectories for some simple paths such as straight lines and circular arcs. Especially for some complex trajectories such as intersecting lines, the derivation process is extremely cumbersome. And some paths generated by the heat deformation of the workpiece, the traditional method is powerless. Moreover, the traditional pendulum welding simply makes the speed component along the direction of the weld uniform. The speed of the trajectory cannot guarantee a uniform speed during welding, and generally fluctuates periodically, which can easily cause accumulation during welding. In order to achieve better welding quality, a truly uniform pendulum welding motion is required. The present invention provides a method for generating a pendulum welding trajectory for any weld path; the specific scheme includes:
[0038] The arc length s is used for trajectory planning to generate a series of corresponding interpolation points, which are converted into matrix form. These interpolation point matrices are right-multiplied by the swing matrix in turn to generate the matrix corresponding to the weaving welding trajectory, and then converted into the interpolation point coordinate form. The relationship between the coordinates of the weaving welding trajectory and the arc length of the weaving welding trajectory is obtained by cubic spline interpolation to re-plan the speed.
[0039] The method of the present invention can realize the weaving welding of any trajectory, and is no longer limited to simple straight lines and arcs; it abandons the cumbersome coordinate system conversion, and very concisely generates a weaving welding trajectory generation model; and can achieve a uniform speed throughout the weaving welding trajectory.
[0040] Therefore, on the one hand, the present invention combines the idea of the Frenet coordinate system to provide an extremely simple and universal method for generating a weaving welding trajectory for any path, and on the other hand, it also provides a speed planning method to ensure that the trajectory runs at a uniform speed.
[0041] This paper provides a method for generating a weaving welding trajectory for any weld path. The main solution is to first calibrate the robot tool coordinate system to determine the swing direction; then the algorithm generates the weaving welding trajectory path based on the interpolation point information of the required welding path, and then performs uniform speed planning throughout the process.
[0042] Now, an overall description will be given with reference to the accompanying drawings. Figure 1 As shown,
[0043] Step 1: Calibrate the robot tool coordinate system to determine the swing direction;
[0044] First of all, the TCP coordinate system of the robot arm needs to be calibrated when using it, where the z direction is the direction of the welding gun; the x axis is the direction of the welding feed, which can be specified by yourself. When teaching points, ensure that the x direction of the TCP is along the tangent direction of the weld; y is the swing direction calculated internally by the algorithm, and the direction of the swing welding plane can be adjusted by adjusting the z axis direction.
[0045] Then the pendulum welding trajectory generation method is carried out. The principle is: after planning the trajectory of a path, a series of interpolation points will be generated. These interpolation points can represent the position of the TCP point and the posture of the TCP when the robot arm runs to this point. The planned TCP coordinate system axis is generally at a fixed angle with the tangent and discovery direction of the path. By periodically offsetting the interpolation points along the TCP coordinate system direction, the pendulum welding trajectory can be quickly generated.
[0046] Step 2: In the calibrated coordinate system, using arc length to perform trajectory planning to generate a corresponding plurality of interpolation points; converting the interpolation points into a matrix form to form an interpolation point matrix;
[0047] When performing trajectory planning, a series of interpolation points P (x, y, z, rx, ry, rz) will be generated. These interpolation points can be generated using velocity planning with arc length s. For each interpolation point, (x, y, z) can be used to represent the origin of the TCP coordinate system at this time, and (rx, ry, rz) can be converted into a rotation matrix R = [n, s, a] to represent the direction of the three coordinate axes of the TCP coordinate system. These interpolation points can all be converted into a series of matrices,
[0048]
[0049] Step 3: The interpolation point matrix is right-multiplied by the swing matrix in sequence to generate a matrix corresponding to the swing welding trajectory, and converted into the interpolation point coordinate form;
[0050] For example, the trajectory is an arc to illustrate this process. Figure 2-4 , is a circular interpolation trajectory generated by doubles speed planning, on which the posture of the TCP coordinate system at some points is marked. In the figure, the z direction is the direction of the welding gun, and the y direction is always the tangent direction of the trajectory. The TCP coordinate system can be compared to the Frenet coordinate system, which is also called the natural coordinate system. It is a coordinate system that describes the position and direction of points on a curve. Then multiply it by a matrix T on the right swing , this right-hand multiplication matrix represents the homogeneous transformation relative to the TCP coordinate system, which can be used to represent the swing. Generate a new swing welding path. At this time, the corresponding point position is
[0051]
[0052] On the basis of this circular trajectory, the interpolation point is periodically offset along the tcp coordinate axis to generate a weaving welding trajectory that fully meets the production requirements. The tcp coordinate system can be compared to the Frenet coordinate system.
[0053] For example, a matrix is right-multiplied, and this right-multiplied matrix represents a homogeneous transformation relative to the TCP coordinate system, which can be used to represent the swing. For example, right-multiply by [1,0,0,0.001; 0,1,0,0; 0,0,1,0; 0,0,0,1], and the new coordinate system origin is the TCP origin translated by 0.001 along the x-axis.
[0054] The rotation matrix part of the swing matrix Tswing is a unit matrix, so that the swing along the three coordinate axes of tcp can be achieved.
[0055] The translation vector part is used to generate the weaving welding trajectory. Figure 2 The zigzag pendulum trajectory shown, the homogeneous transformation matrix used to characterize the zigzag swing is as follows:
[0056]
[0057] for Figure 3 The homogeneous transformation matrix used to characterize the sinusoidal pendulum trajectory shown is as follows:
[0058]
[0059] for Figure 4 The spiral pendulum trajectory shown; the homogeneous transformation matrix used to characterize and spiral swing is as follows:
[0060]
[0061] Where a is the swing welding width, w is the swing welding spacing, and s is the trajectory arc length corresponding to the interpolation point at this time.
[0062] Specific implementation cases:
[0063] The method for generating interpolation points of constant speed oscillating welding is as follows:
[0064] Step 1: Use trajectory planning to obtain a large number of interpolation points Pi (xi, yi, zi)
[0065] To plan the trajectory, generally speaking, straight lines and arcs can be planned with arc length, and splines can be planned with parameter u.
[0066] Taking the spline as an example, its spatial coordinate P has a one-to-one correspondence with the parameter u. () By performing s-type speed planning on the parameter u, a large number of interpolation points (xi, yi, zi) can be obtained. In order to strictly guarantee the accuracy, when using it, the number of interpolation points must reach the distance between two adjacent interpolation points to meet the bow height error requirements.
[0067] Step 2: Interpolate to obtain the relationship between arc length s and spatial coordinates P (x, y, z)
[0068] Then we can use cubic spline interpolation to obtain the relationship between arc length s and spatial coordinates P(x, y, z), as follows:
[0069] x0, y0, z0 corresponds to s0=0;
[0070] xi,yi,zi correspond to si=si-1+sqrt((xi-xi-1)^2+(yi-yi-1)^2+(zi-zi-1)^2), i=1,2,...,i...
[0071] Get the functional relationship x(s), y(s), z(s).
[0072] Step 3: Constant speed planning for arc length
[0073] Then, the arc length s is planned at a constant speed, and the obtained s sequence is substituted into x(s), y(s), z(s) to obtain the interpolation point with constant linear speed. Here, s can also be planned into other speed plans such as ladder-type speed planning and s-type speed planning.
[0074] The method of the present invention is relatively simple, and the interpolation calculation of the cubic spline is also very simple. Cubic spline interpolation is a classic interpolation method, and there are many documents introducing its principle, which belongs to the content of the prior art, and the present invention will not repeat it. When there are fewer interpolation points, the accuracy cannot be guaranteed, because here almost tens of thousands of interpolation points are used for interpolation, and because the interpolation points are very dense, the accuracy can be guaranteed.
[0075] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this article.
[0076] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0077] In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.
[0078] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this article.
[0079] In addition, each functional unit in each embodiment of this invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional unit.
[0080] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this article is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this article. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.
[0081] Specific embodiments are used in this article to illustrate the principles and implementation methods of this article. The description of the above embodiments is only used to help understand the methods and core ideas of this article. At the same time, for general technicians in this field, according to the ideas of this article, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on this article.
Claims
1. A method for generating a weaving welding trajectory for an arbitrary weld path, characterized in that: The following steps are involved: Step 1: Calibrate the robot tool coordinate system to determine the swing direction; Step 2: In the calibrated coordinate system, using arc length to perform trajectory planning to generate a corresponding plurality of interpolation points; converting the interpolation points into a matrix form to form an interpolation point matrix; Step 3: The interpolation point matrix is right-multiplied by the swing matrix in sequence to generate a matrix corresponding to the swing welding trajectory, and converted into the interpolation point coordinate form; Step 4: Based on the interpolation point coordinates and the arc length of the weaving welding trajectory, use cubic spline interpolation to determine the relationship between the two and re-plan the speed.
2. A method for generating a weaving welding trajectory for an arbitrary weld path according to claim 1, characterized in that: The robot arm tool coordinate system is calibrated to determine the swing direction; include Calibrate the TCP coordinate system of the robot arm, where the z direction is the direction of the welding gun; the x axis is the direction of the welding feed. During point teaching, ensure that the x direction of the TCP is along the tangent direction of the weld; y is the swing direction calculated internally by the algorithm. The direction of the swing welding plane can be adjusted by adjusting the z axis direction.
3. A method for generating a weaving welding trajectory for an arbitrary weld path according to claim 2, characterized in that: In the calibrated coordinate system, arc length is used to perform trajectory planning to generate corresponding interpolation points; the interpolation points are converted into a matrix form to form an interpolation point matrix; include When performing trajectory planning, a series of interpolation points P (x, y, z, rx, ry, rz) are generated; these interpolation points are generated using speed planning with an arc length of s; for each interpolation point, (x, y, z) can be used to represent the origin of the TCP coordinate system at this time, and (rx, ry, rz) can be converted into a rotation matrix R = [n, s, a] to represent the direction of the three coordinate axes of the TCP coordinate system; these interpolation points are all converted into a series of matrices:
4. A method for generating a weaving welding trajectory for an arbitrary weld path according to claim 3, characterized in that: The interpolation point matrix is right-multiplied by the swing matrix in sequence to generate a matrix corresponding to the swing welding trajectory, and converted into the interpolation point coordinate form, including Multiply right by a matrix T swing , this right-hand multiplication matrix represents the homogeneous transformation matrix relative to the TCP coordinate system, which is used to represent the swing; the corresponding points of the new swing welding path are generated at this time:
5. A method for generating a weaving welding trajectory for an arbitrary weld path according to claim 4, characterized in that: The matrix T swing It is a swing matrix, and its rotation matrix part is the unit matrix, so that the swing along the three coordinate axes of TCP can be realized.
6. A method for generating a weaving welding trajectory for an arbitrary weld path according to claim 4, characterized in that: The trajectory is planned as a circular trajectory, and the homogeneous transformation matrix includes a homogeneous transformation matrix that characterizes the fold line swing: Homogeneous transformation matrix of sinusoidal oscillation: The homogeneous transformation matrix of the spiral swing is as follows: Where a is the swing welding width, w is the swing welding spacing, and s is the trajectory arc length corresponding to the interpolation point at this time.
7. A device for generating a weaving welding trajectory for any weld path, characterized in that: It comprises a processor and a memory; the memory is used to store a program; the processor executes the program to implement the method as described in any one of claims 1-6.
8. A computer-readable storage medium, characterized in that: The storage medium stores a program, and the program is executed by a processor to implement the method according to any one of claims 1 to 6.