Robot welding positioning method based on least squares method

Abstract

The present invention relates to a robot welding positioning method based on the least squares method, which comprises the following steps: first, obtaining a discrete sampling point set of the edge contour of a workpiece to be welded by linear scanning; then, performing curve fitting on the sampling point set using the LLS algorithm to determine a baseline and calculate a deviation, and during fitting, downsampling can be performed first and a weight factor can be introduced to balance the influence of the sampling points; then, based on the baseline, polar coordinate data is converted into a coordinate point set in a Cartesian coordinate system; and a three-dimensional space welding trajectory dynamic compensation model is constructed, comprising using a piecewise cubic spline interpolation algorithm to smooth the coordinate point set to generate a weld baseline curve, collecting thermal deformation through a laser displacement sensor to establish a temperature-deformation coupling compensation matrix, and performing superposition operations to generate a corrected target path equation; and controlling the operation of the robot welding arm according to the corrected target path equation, thereby effectively coping with various factors in the welding process and improving welding quality and efficiency.

Description

Technical Field

[0001] The present invention relates to the field of robot control, and in particular to a robot welding positioning method based on the least squares method. Background Art

[0002] With the popularization of robots, manual welding methods have gradually been replaced in industry to perform various types of workpiece welding. Generally, there are two methods to control the movement of the robot. One is to use a handheld operator to teach the position, so that the robot repeats the movement according to the taught position. This method has poor adaptability, has high requirements for workpiece assembly and positioning, and requires a certain amount of robot working experience. The other is to generate a welding trajectory by an external program and send the trajectory to control the movement of the robot. Generally, the workpiece is placed around the robot, and the movement trajectory of the robot welding gun is generated according to the workpiece parameters and placement position, so that the welding gun scans and welds around the workpiece. This method requires the calibration of the external tool TCP, which is difficult to calibrate the absolute accuracy. For some workpieces, a positioner or external axis is required, which increases the complexity of the system.

[0003] In Chinese patent CN113770577B, a method for generating a trajectory for a workpiece mounted on a robot is described. Multiple virtual coordinate systems are established using workpiece parameters or a set of preferred points derived from actual scanning. These virtual coordinate systems perform only trajectory calculations and do not control robot motion. Trajectories are calculated using the rotational and translational relationships between the virtual coordinate systems and the workpiece weld model. The robot is then controlled to follow the calculated trajectory using its built-in flange coordinate system, ensuring that all weld point sets pass through the same point for scanning or welding. Although the aforementioned scheme calculates the trajectory using the established virtual coordinate system and then directly controls the robot's trajectory using the flange coordinate system, thereby avoiding the impact of manual TCP calibration on the robot's absolute accuracy and avoiding mechanical motion other than that performed by the robot, reducing mechanical complexity, the establishment of the virtual coordinate system is highly dependent on preset workpiece parameters or initial scan data. When the workpiece exhibits assembly errors, thermal deformation, or positional drift during machining, the existing virtual coordinate system cannot be dynamically corrected, causing the trajectory to deviate from the actual weld position.

[0004] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0005] The present invention proposes a robot welding positioning method based on the least squares method, which aims to solve the problem in the prior art that when the workpiece has assembly errors, thermal deformation or position drift during processing, the existing virtual coordinate system cannot be dynamically corrected, causing the trajectory to deviate from the actual weld position.

[0006] To achieve the above object, the present invention proposes a robot welding positioning method based on the least squares method, comprising the following steps:

[0007] S1. Obtain a discrete sampling point set of the edge contour of the workpiece to be welded by linear array scanning.

[0008] S2. Perform curve fitting on the discrete sampling point set of the workpiece edge obtained in step S1 using the LLS algorithm to determine the baseline of the welding path and calculate the deviation from the ideal welding path.

[0009] S3. Based on the welding path reference line determined in step S2, the polar coordinate data is converted into a Cartesian coordinate system to obtain a coordinate point set of the workpiece edge in the Cartesian coordinate system.

[0010] S4. Based on the Cartesian coordinate point set of the workpiece edge obtained in step S3, a dynamic compensation model of the three-dimensional welding trajectory is constructed, including:

[0011] S41. Use piecewise cubic spline interpolation algorithm to smooth the coordinate point set and generate a continuous and differentiable weld reference curve.

[0012] S42, using laser displacement sensors to collect thermal deformation in the welding process in real time and establish a temperature-deformation coupling compensation matrix ;in, is the linear offset of the three axes of the Cartesian coordinate system caused by thermal deformation; Both are angular deformations around the X / Y axis.

[0013] S43. Superimpose the ideal welding path parameter equation P0(t) and the real-time compensation amount to generate a corrected target path equation:

[0014]

[0015] k is the system stiffness coefficient, α is the heat diffusion attenuation factor, and P(t) is the corrected target path.

[0016] S5. Control the robot welding arm to perform welding operations according to the corrected target path equation generated in step S4.

[0017] Preferably, the piecewise cubic spline interpolation algorithm used in step S4 is specifically:

[0018] S411, sorting the Cartesian coordinate point set of the workpiece edge obtained in step S3 to ensure the order of the interpolation process;

[0019] S412, dividing the coordinate point set into several segments according to the shape of the workpiece edge and welding requirements, each segment containing at least four control points;

[0020] S413, applying a cubic spline interpolation algorithm to each segment of control points to calculate an interpolation function within the segment;

[0021] S414. Ensure that the interpolation functions of all segments are continuous and smooth at the connection points to form a complete weld reference curve.

[0022] Preferably, the process of constructing the temperature-deformation coupling compensation matrix in step S42 includes:

[0023] S421. Before welding begins, perform an initial scan of the workpiece using a laser displacement sensor to record an initial set of coordinate points of the workpiece before it is affected by thermal deformation as a reference.

[0024] S422. During the welding process, temperature data of the welding area is collected in real time, and the deformation of the workpiece caused by the temperature change is calculated using a pre-established temperature-deformation relationship model;

[0025] S423, based on the deformation calculated in step S422 and the initial coordinate point set in step S421, calculate the linear offset of the three axes of the Cartesian coordinate system and the angular deformation around the X / Y axis caused by thermal deformation;

[0026] S424: Integrate the calculated linear offset and angular deformation into the temperature-deformation coupling compensation matrix for subsequent path correction calculation.

[0027] Preferably, the process of converting the polar coordinate data into a Cartesian coordinate system in step S3 to obtain a coordinate point set of the workpiece edge in the Cartesian coordinate system includes:

[0028] S31. Establish the conversion relationship between the polar coordinate system and the Cartesian coordinate system. The conversion formula is as follows:

[0029]

[0030] Among them, r is the polar diameter, θ is the polar angle, and z is the height coordinate.

[0031] S32 , traverse the discrete sampling point set of the workpiece edge obtained in step S1 , apply the above conversion formula to each sampling point, and calculate its coordinate value in the Cartesian coordinate system.

[0032] S33. All converted coordinate points are stored in sequence to form a coordinate point set of the workpiece edge in the Cartesian coordinate system.

[0033] Preferably, in step S3, the welding path reference line is specifically a V-shaped notch formed by two straight line segments, or a U-shaped notch formed by a local small arc.

[0034] Preferably, in step S2, when performing curve fitting by the LLS algorithm, the discrete sampling point set of the edge contour of the welding workpiece is first downsampled, and the downsampling factor is adaptively determined according to the edge size of the welding workpiece and the edge point distribution density, and the value range is [0.1, 0.5].

[0035] Preferably, in step S2, when performing curve fitting using the LLS algorithm, a weight factor is introduced to balance the influence of different sampling points on the fitting result.

[0036] Preferably, the weight factor is determined by the inverse of the square of the distance from the welding path reference line to the geometric center line of the workpiece notch.

[0037] The beneficial effects of the technical solution of the present invention are:

[0038] Using the least squares method (LLS) to perform curve fitting on discrete sampling points along the workpiece edge accurately determines the weld path baseline and calculates the deviation from the ideal weld path. By converting polar coordinate data into a Cartesian coordinate system, the shape and position of the workpiece edge can be more accurately described, providing a foundation for the subsequent construction of a dynamic compensation model.

[0039] The coordinate point set is smoothed using a piecewise cubic spline interpolation algorithm to generate a continuous and differentiable weld reference curve. This ensures smoothness while reducing computational complexity and improving efficiency. Furthermore, a laser displacement sensor is used to collect real-time thermal deformation during welding, establishing a temperature-deformation coupling compensation matrix. This effectively eliminates welding errors caused by thermal deformation and improves welding quality. The ideal welding path parameter equation, P0(t), is then superimposed with the real-time compensation value to generate a revised target path equation. This allows the welding path to be adjusted according to actual conditions, bringing it closer to the ideal state.

[0040] By meticulously sorting and segmenting the Cartesian coordinate points of the workpiece edge, the interpolation process is sequential and the local control points are rational. Each segment contains at least four control points, enabling cubic spline interpolation to more accurately reflect the actual shape of the workpiece edge, thereby improving the accuracy of the weld path. This also ensures a smooth transition of the weld reference curve within each segment, avoiding the sharp corners or sudden changes that can occur with traditional straight-line or simple curve interpolation. This reduces stress concentration and weld defects during the welding process, significantly improving the overall weld quality.

[0041] By constructing a temperature-deformation coupling compensation matrix, the linear offset and angular deformation caused by thermal deformation can be accurately calculated, and real-time compensation can be performed during the welding process, effectively reducing welding errors and improving the overall accuracy of the product. Simultaneously, by collecting temperature data and calculating deformation in real time, the system can quickly respond to thermal deformation during welding, reducing welding interruptions or rework caused by deformation, shortening the welding cycle, and improving production efficiency. Furthermore, before welding begins, a laser displacement sensor records the workpiece's initial coordinate point set, providing a precise baseline for subsequent deformation calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The figure is a flow chart of an embodiment of the subject matter of the present invention.

[0043] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings to clearly and completely describe the solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0046] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element.

[0047] Furthermore, if terms such as "first" or "second" are used in this disclosure, they are for descriptive purposes only (e.g., to distinguish between identical or similar components) and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include at least one such feature. Furthermore, the technical solutions of various embodiments may be combined, but only if they are achievable by persons of ordinary skill in the art. If a combination of technical solutions contradicts or is unachievable, such combination shall be deemed non-existent and outside the scope of protection claimed by this disclosure.

[0048] See also Figure 1 The present invention proposes a robot welding positioning method based on the least squares method, comprising the following steps:

[0049] S1. Obtain a discrete sampling point set of the edge contour of the workpiece to be welded by linear array scanning.

[0050] S2. Performing curve fitting on the discrete sampling point set of the workpiece edge obtained in step S1 using an LLS algorithm to determine a baseline of the welding path and calculate the deviation from the ideal welding path. The LLS algorithm is a least squares method that specifically seeks a best-fit curve such that the sum of the vertical distances from all discrete points to the curve is minimized.

[0051] S3. Based on the welding path reference line determined in step S2, the polar coordinate data is converted into a Cartesian coordinate system to obtain a coordinate point set of the workpiece edge in the Cartesian coordinate system.

[0052] S4. Based on the Cartesian coordinate point set of the workpiece edge obtained in step S3, a dynamic compensation model of the three-dimensional welding trajectory is constructed, including:

[0053] S41. Use piecewise cubic spline interpolation algorithm to smooth the coordinate point set and generate a continuous and differentiable weld reference curve.

[0054] S42, using laser displacement sensors to collect thermal deformation in the welding process in real time and establish a temperature-deformation coupling compensation matrix ;in, is the linear offset of the three axes of the Cartesian coordinate system caused by thermal deformation; Both are angular deformations around the X / Y axis.

[0055] S43. Superimpose the ideal welding path parameter equation P0(t) and the real-time compensation amount to generate a corrected target path equation:

[0056]

[0057] Where k is the system stiffness coefficient; is the linear offset of the three axes of the Cartesian coordinate system caused by thermal deformation; P(t) is the corrected target path, Where α is the thermal diffusion attenuation factor, which describes the diffusion and attenuation characteristics of thermal deformation during the entire welding process; as time goes by, heat gradually conducts and diffuses inside the workpiece, and the thermal deformation will change accordingly; It is expressed as the exponential decay law of thermal deformation with time, and the influence of thermal deformation is greater at the beginning of welding, and gradually decreases as time goes by. It indicates the thermal deformation compensation amount after considering the thermal deformation diffusion and attenuation characteristics at different times during the welding process.

[0058] S5. Control the robot welding arm to perform welding operations according to the corrected target path equation generated in step S4.

[0059] In this embodiment, the least squares method (LLS) is used to perform curve fitting on discrete sampling points along the workpiece edge. This method accurately determines the weld path baseline and calculates the deviation from the ideal weld path. By converting polar coordinate data into a set of Cartesian coordinate points, the shape and position of the workpiece edge can be more accurately described, providing a foundation for the subsequent construction of a dynamic compensation model.

[0060] On the other hand, the coordinate point set is smoothed using a piecewise cubic spline interpolation algorithm to generate a continuous and differentiable weld reference curve. This ensures smoothness while reducing computational complexity and improving efficiency. Furthermore, a laser displacement sensor is used to collect real-time thermal deformation during welding, and a temperature-deformation coupling compensation matrix is ​​established. This effectively eliminates welding errors caused by thermal deformation and improves welding quality. The ideal welding path parameter equation, P0(t), is then superimposed with the real-time compensation value to generate a revised target path equation. This allows the welding path to be adjusted according to actual conditions, bringing it closer to the ideal state.

[0061] In one embodiment, the piecewise cubic spline interpolation algorithm used in step S4 is specifically:

[0062] S411 , sorting the Cartesian coordinate point set of the workpiece edge obtained in step S3 to ensure the sequence of the interpolation process.

[0063] S412. Divide the coordinate point set into several segments according to the shape of the workpiece edge and welding requirements, each segment containing at least four control points.

[0064] S413: Apply the cubic spline interpolation algorithm to each segment of control points to calculate the interpolation function within the segment.

[0065] S414. Ensure that the interpolation functions of all segments are continuous and smooth at the connection points to form a complete weld reference curve.

[0066] For example, the Cartesian coordinate point set of the workpiece edge Divide into m segments, each segment contains four control points; further, apply the cubic spline interpolation algorithm to each segment of control points to calculate the interpolation function within the segment. The form of each segment interpolation function Si(x) is:

[0067]

[0068] Subsequently, the interpolation functions of all segments are guaranteed to be continuous and smooth at the connection points to form a complete weld reference curve. The following conditions are ensured to be met at each connection point to obtain a continuous and smooth weld reference curve:

[0069]

[0070] In this embodiment, the precise sorting and segmentation of the Cartesian coordinate point set of the workpiece edge ensures the sequential nature of the interpolation process and the rationality of the local control points. Each segment contains at least four control points, enabling cubic spline interpolation to more accurately reflect the actual shape of the workpiece edge, thereby improving the accuracy of the weld path. This also ensures a smooth transition of the weld reference curve within each segment, avoiding the sharp corners or sudden changes that can occur with traditional straight-line or simple curve interpolation. This, in turn, reduces stress concentration and weld defects during welding, significantly improving the overall weld quality.

[0071] On the other hand, the segmentation strategy and the number of control points can be flexibly adjusted according to the specific shape of the workpiece edge and the welding requirements, so that high-quality weld reference curves can be generated for workpieces with complex geometric shapes, enhancing the adaptability and flexibility of the process.

[0072] In one embodiment, the process of constructing the temperature-deformation coupling compensation matrix in step S42 includes:

[0073] S421. Before welding begins, perform an initial scan of the workpiece using a laser displacement sensor to record the initial coordinate point set of the workpiece before it is affected by thermal deformation. , as a reference benchmark.

[0074] S422. During the welding process, the temperature data of the welding area is collected in real time, and the deformation of the workpiece caused by the temperature change is calculated through a pre-established temperature-deformation relationship model.

[0075] S423 , based on the deformation calculated in step S422 and in combination with the initial coordinate point set in step S421 , the linear offset of the three axes of the Cartesian coordinate system and the angular deformation around the X / Y axis caused by thermal deformation are calculated.

[0076] S424: Integrate the calculated linear offset and angular deformation into the temperature-deformation coupling compensation matrix for subsequent path correction calculation.

[0077] In this embodiment, by constructing a temperature-deformation coupling compensation matrix, the linear offset and angular deformation caused by thermal deformation can be accurately calculated, and real-time compensation can be performed during the welding process, effectively reducing welding errors and improving the overall accuracy of the product. Furthermore, by collecting temperature data and calculating deformation in real time, the system can quickly respond to thermal deformation during welding, reducing welding interruptions and rework caused by deformation, shortening the welding cycle, and improving production efficiency. Furthermore, before welding begins, a laser displacement sensor records the workpiece's initial coordinate point set, providing a precise baseline for subsequent deformation calculations.

[0078] Furthermore, traditional welding methods often generate significant stress within the workpiece due to their inability to effectively control thermal deformation, which can affect the long-term service life of the equipment. However, this embodiment compensates for thermal deformation in real time, reducing stress accumulation within the workpiece and the risk of equipment damage due to overheating and deformation, thereby extending the equipment's service life and lowering maintenance costs.

[0079] In one embodiment, the process of converting the polar coordinate data into a Cartesian coordinate system to obtain a coordinate point set of the workpiece edge in the Cartesian coordinate system in step S3 includes:

[0080] S31. Establish the conversion relationship between the polar coordinate system and the Cartesian coordinate system. The conversion formula is as follows:

[0081]

[0082] Among them, r is the polar diameter, θ is the polar angle, and z is the height coordinate;

[0083] S32 , traverse the discrete sampling point set of the workpiece edge obtained in step S1 , apply the above conversion formula to each sampling point, and calculate its coordinate value in the Cartesian coordinate system.

[0084] S33. All converted coordinate points are stored in sequence to form a coordinate point set of the workpiece edge in the Cartesian coordinate system.

[0085] Furthermore, in step S3, the welding path reference line is specifically a V-shaped notch formed by two straight line segments, and / or a U-shaped notch formed by a local small arc.

[0086] In this embodiment, the conversion from polar coordinates to Cartesian coordinates makes welding path planning more intuitive and accurate. Furthermore, in a Cartesian coordinate system, the welding path can be more easily defined and adjusted, ensuring that the welding head precisely follows the workpiece edge, thereby reducing welding deviations and errors. Furthermore, by constructing a V-shaped notch formed by two straight line segments or a U-shaped notch formed by a localized small arc as the welding path baseline, the system can better adapt to welding tasks of varying shapes and requirements, enabling the welding process to be optimized for the geometric characteristics of different workpieces, thereby improving welding quality and efficiency.

[0087] In one embodiment, in step S2, when performing curve fitting using the LLS algorithm, a discrete sampling point set of the edge contour of the welding workpiece is first downsampled, and the downsampling factor is adaptively determined according to the edge size of the welding workpiece and the edge point distribution density, and the value range is [0.1, 0.5].

[0088] In this embodiment, by adaptively downsampling the discrete sampling point set of the edge contour of the welding workpiece before curve fitting by the LLS algorithm, not only the calculation efficiency and fitting accuracy are optimized, but also the adaptability and versatility of the system are enhanced, and the welding quality is significantly improved.

[0089] In one embodiment, in step S2, when performing curve fitting using the LLS algorithm, a weight factor is introduced to balance the influence of different sampling points on the fitting result.

[0090] Furthermore, the weight factor is specifically determined by the reciprocal of the square of the distance from the welding path reference line to the geometric center line of the workpiece notch.

[0091] In this embodiment, the introduction of weighting factors allows the curve fitting process to more carefully consider the impact of different sampling points on the fitting results. By assigning higher weights to sampling points closer to the weld path baseline, key points can be more accurately reflected in the fitting results, thereby improving overall fitting accuracy. Furthermore, the weighting factor is determined by the inverse of the square of the distance from the weld path baseline to the geometric centerline of the workpiece notch, making this embodiment flexible and adaptable to welded workpieces of varying shapes and sizes. Whether for complex geometries or diverse welding positions, the optimal fitting effect can be ensured by adjusting the weighting factors, demonstrating strong adaptability and versatility.

[0092] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. Any equivalent structural transformation made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields, is included in the scope of protection of the present invention.

Claims

1. A robot welding positioning method based on least squares method, characterized in that: The following steps are involved: S1, obtaining a discrete sampling point set of the edge contour of the workpiece to be welded by linear array scanning; S2. Performing curve fitting on the discrete sampling point set obtained in step S1 using an LLS algorithm to determine a baseline of the welding path, and calculating a deviation between the baseline of the welding path and the ideal welding path; S3. Based on the reference line of the welding path determined in step S2, the polar coordinate data is converted into a Cartesian coordinate system to obtain a coordinate point set of the workpiece edge contour in the Cartesian coordinate system. The process of converting the polar coordinate data into a Cartesian coordinate system to obtain a coordinate point set of the workpiece edge contour in the Cartesian coordinate system includes: S31. Establish the conversion relationship between the polar coordinate system and the Cartesian coordinate system. The conversion formula is as follows: Among them, r is the polar diameter, θ is the polar angle, and z is the height coordinate; S32, traversing the discrete sampling point set obtained in step S1, applying the above conversion formula to each sampling point, and calculating its coordinate value in the Cartesian coordinate system; S33, storing all converted coordinate points in order to form a coordinate point set of the workpiece edge contour in a Cartesian coordinate system; S4. Based on the coordinate point set obtained in step S3, a dynamic compensation model of the three-dimensional welding trajectory is constructed, including: S41, using a piecewise cubic spline interpolation algorithm to smooth the coordinate point set obtained in step S3 to generate a continuous and differentiable weld reference curve; S42, using laser displacement sensors to collect thermal deformation in the welding process in real time and establish a temperature-deformation coupling compensation matrix ;in, is the linear offset of the three axes of the Cartesian coordinate system caused by thermal deformation; are all angular deformations around the X / Y axis; S43, The ideal welding path P0(t) is the real-time compensation value, and the real-time compensation value is superimposed to generate the corrected target path equation: , k is the system stiffness coefficient, α is the heat diffusion attenuation factor, and P(t) is the corrected target path; S5. Controlling the robot welding arm to perform welding operations according to the corrected target path equation generated in step S4; In step S3, the reference line of the welding path is specifically a V-shaped notch formed by two straight line segments, or a U-shaped notch formed by a local small arc; the piecewise cubic spline interpolation algorithm used in step S4 is specifically: S411, sorting the coordinate point set obtained in step S3 to ensure the order of the interpolation process; S412, dividing the sorted coordinate point set into several segments according to the shape of the workpiece edge contour and welding requirements, each segment containing at least four control points; S413, applying a cubic spline interpolation algorithm to each control point in each segment to calculate an interpolation function within the segment; S414. Ensure that the interpolation functions of all segments are continuous and smooth at the connection points to form a complete weld reference curve; The process of constructing the temperature-deformation coupling compensation matrix in step S42 includes: S421. Before welding begins, perform an initial scan of the workpiece using a laser displacement sensor to record an initial set of coordinate points of the workpiece before it is affected by thermal deformation as a reference. S422. During the welding process, temperature data of the welding area is collected in real time, and the deformation of the workpiece caused by the temperature change is calculated using a pre-established temperature-deformation relationship model; S423, based on the workpiece deformation calculated in step S422 and the initial coordinate point set in step S421, calculate the linear offset of the three axes of the Cartesian coordinate system and the angular deformation around the X / Y axis caused by thermal deformation; S424: Integrate the calculated linear offset and angular deformation into the temperature-deformation coupling compensation matrix for subsequent path correction calculation.

2. The robot welding positioning method based on the least squares method according to claim 1, characterized in that: In step S2, when performing curve fitting using the LLS algorithm, the discrete sampling point set is first downsampled, and the downsampling factor is adaptively determined according to the edge size of the workpiece to be welded and the edge point distribution density, and the value range is [0.1, 0.5].

3. The robot welding positioning method based on the least squares method according to claim 2, characterized in that: In step S2, when performing curve fitting using the LLS algorithm, a weight factor is introduced to balance the influence of different sampling points on the fitting result.

4. The robot welding positioning method based on the least squares method according to claim 3, characterized in that: The weight factor is determined according to the inverse of the square of the distance from the reference line of the welding path to the geometric center line of the workpiece notch.

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