A stud position precision control method based on offline programming

Abstract

The application discloses a stud position precision control method based on offline programming, which comprises the following steps: 1) eliminating the movement deviation of three external shafts by setting a base point; and 2) measuring the actual movement distance of a stud welding robot by using a double-frequency laser interferometer, establishing a data relationship by multiple point measurement, calculating a fitting curve equation, and obtaining the relationship between the actual movement distance and the theoretical movement distance, i.e. quantifying the deviation to compensate for the precision loss caused by the joint movement of the robot. The method improves the dimensional precision of the stud welding robot welding attachment, reduces the wrong welding, and reduces the repair amount of the attachment. Meanwhile, the dimensional precision of the group attachment is improved, and the assembly efficiency and assembly quality of the assembly are improved.

Description

Technical Field

[0001] This invention relates to a stud position accuracy control method based on offline programming. Background Technology

[0002] To improve the stability and consistency of welding quality, a new automated deck welding unit was constructed, incorporating both robotic stud welding and robotic arc welding. The entire stud welding equipment consists of two parts: an external axis and a stud welding robot. The robot is mounted on a slide rail and its movement in three-dimensional space is controlled by the external axes (X, Y, Z). The stud welding robot has six axes: axes 1, 2, and 3 can deliver the end-effector welding torch to different spatial positions, while axes 4, 5, and 6 address different welding posture requirements. Due to limitations in instruments and environmental factors, the external axis and the stud welding robot cannot be infinitely precise; a certain deviation will exist between the robot's theoretical displacement and its actual displacement, affecting the dimensional accuracy of the attachments and, in severe cases, causing the entire vehicle attachment to be reworked. Therefore, solving these problems is imperative. Summary of the Invention

[0003] The purpose of this invention is to provide a stud position accuracy control method based on offline programming to solve the problems existing in the prior art.

[0004] The technical solution adopted to achieve the purpose of this invention is as follows: a stud position accuracy control method based on offline programming, comprising the following steps:

[0005] 1) The robot is installed on the XYZ moving track, and the XYZ moving track is fixed on a horizontal working platform; wherein, the robot is equipped with a stud gripping device and a welding torch;

[0006] 2) Select a coordinate origin on the working platform and place the tip of the robot's special positioning cone I on the coordinate origin; wherein, the coordinate origin is located at point O of the plane coordinate system O-X1Y1;

[0007] 3) The robot grasps the special positioning cone II and aligns the tip of the special positioning cone II with the tip of the special positioning cone I;

[0008] 4) The robot controls the welding torch to rotate 360° around the special positioning cone II. During the rotation of the welding torch, the tip of the special positioning cone II is kept aligned with the tip of the special positioning cone I to eliminate the movement deviation of the XYZ moving track.

[0009] 5) Control the robot to move to different points on the XYZ movement track, measure the actual movement distance of the robot, take O point as the origin, record the theoretical coordinates (x, y) and actual coordinates (x', y') of the point, the positioning deviation of X1 direction is Δx = x'-x, the relationship between the positioning deviation of X1 direction and the theoretical movement distance is recorded as Δx = f(x), the positioning deviation of Y1 direction is Δy = y'-y, the relationship between the positioning deviation of Y1 direction and the theoretical movement distance is recorded as Δy = h(y);

[0010] 6) Repeat step 5) several times, fit several Δx = f(x) to obtain the fitting curve equation of X1 direction as Δx = kx, fit several Δy = h(y) to obtain the fitting curve equation of Y1 direction as Δy = dy, the coefficients k and d are the deviation compensation parameters of the joint movement of the robot in X1 direction and Y1 direction, and the user adjusts the movement parameters in the robot control program based on the deviation compensation parameters.

[0011] Further, in step 5), a dual-frequency laser interferometer is used to measure the actual movement distance of the robot.

[0012] Further, the special positioning conical I and the special positioning conical II are consistent in structure and size, the structure includes a conical structure and a cylindrical structure, the diameter of the large diameter end of the conical structure is consistent with the diameter of the cylindrical structure, and the large diameter end of the conical structure is connected with the end of the cylindrical structure.

[0013] The technical effect of the present application is self-evident, the method improves the size precision of the stud welding robot welding attachment, reduces the wrong welding, reduces the repair amount of the attachment, at the same time, improves the size precision of the group attachment, improves the assembly efficiency and assembly quality of the assembly. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a schematic view of the special positioning conical for robot;

[0015] Figure 2 It is a schematic view of x-Δx relationship. DETAILED DESCRIPTION

[0016] The present application will be further described below in conjunction with examples, but should not be understood as limiting the above-mentioned subject matter of the present application to the following examples. According to ordinary technical knowledge and conventional means in the art, various substitutions and modifications can be made without departing from the above-mentioned technical idea of the present application, and all should be included in the protection scope of the present application.

[0017] Example 1:

[0018] The present embodiment discloses a stud position precision control method based on offline programming, comprising the following steps:

[0019] 1) install the robot on the XYZ moving track and fix the XYZ moving track on the horizontal work platform; wherein the robot is equipped with stud grabbing device and welding gun;

[0020] 2) select a coordinate origin, referred to as base point, on the work platform, and place the tip of the special positioning cone I of the robot on the base point;

[0021] 3) the robot grabs the special positioning cone II and aligns the tip of the special positioning cone II with the tip of the special positioning cone I; wherein the special positioning cone I and the special positioning cone II are consistent in structure and size, see Figure 1 , the structure includes a conical structure and a cylindrical structure, the diameter of the large diameter end of the conical structure is consistent with the diameter of the cylindrical structure, and the large diameter end of the conical structure is connected with the end of the cylindrical structure;

[0022] 4) the robot controls the welding gun to rotate 360° around the special positioning cone II, and keeps the tip of the special positioning cone II aligned with the tip of the special positioning cone I during the rotation of the welding gun, eliminates the movement deviation of the XYZ moving track, and makes the positioning accuracy and repeatability of the robot at the base point 0; in addition, the base point can be set multiple times according to the reachable range of the robot to ensure that the reachable range of the stud welding robot covers the entire work platform;

[0023] 5) control the robot to move to different points on the XYZ moving track, measure the actual moving distance of the robot by using a double-frequency laser interferometer, record the theoretical coordinates (x, y) and actual coordinates (x', y') of the points with the base point as the origin, the positioning deviation in X1 direction is Δx = x'-x, and the relationship between the positioning deviation in X1 direction and the theoretical moving distance is recorded as Δx = f(x), the positioning deviation in Y1 direction is Δy = y'-y, and the relationship between the positioning deviation in Y1 direction and the theoretical moving distance is recorded as Δy = h(y);

[0024] 6) repeat step 5) several times, see Figure 2The fitting curve equation of X1 direction is obtained by fitting several Δx = f(x), and the discrete data points are approximately distributed according to a one-order equation, the offset distance is n when the special positioning cone II driven by the robot moves m in the X1 direction, and Δx = x / m*n, the deviation compensation parameter k of the X1 direction is n / m, and the compensation coordinate x'' of the X1 direction is x'' = x-Δx, that is, x'' = x-x / m*n; similarly, the fitting curve equation of Y1 direction is obtained by fitting several Δy = h(y), and the coefficient d is the deviation compensation parameter of the joint movement Y1 direction of the robot, the Y1 direction compensation coordinate y'' is obtained by moving measurement and operation, (x'', y'') is used for welding in the stud welding program, and the theoretical size is coincided after compensation, and the precision loss due to the joint movement of the robot is compensated.

[0025] It is worth mentioning that the method described in the embodiment is suitable for the technical field of robot stud welding of armored vehicle body, can compensate the deviation due to the joint movement of the robot, improve the positioning precision and repeat precision of stud welding attachment, solve the problems of poor size precision, low repeat precision and large area repair of stud welding attachment, and is a precise and efficient control method.

[0026] Embodiment 2:

[0027] The embodiment discloses a stud position precision control method based on offline programming, comprising the following steps:

[0028] 1) The robot is installed on the XYZ moving track, and the XYZ moving track is fixed on the horizontal workbench; wherein the robot is equipped with a stud grabbing device and a welding gun;

[0029] 2) A coordinate origin is selected on the workbench, and the tip of the special positioning cone I of the robot is placed on the coordinate origin; wherein the coordinate origin is located on the O point of the plane coordinate system O-X1Y1;

[0030] 3) The robot grabs the special positioning cone II and aligns the tip of the special positioning cone II with the tip of the special positioning cone I;

[0031] 4) The robot controls the welding gun to rotate 360° around the special positioning cone II, and the tip of the special positioning cone II is kept aligned with the tip of the special positioning cone I during the rotation of the welding gun, so as to eliminate the movement deviation of the XYZ moving track;

[0032] 5) Control the robot to move to different points on the XYZ movement track, measure the actual movement distance of the robot, take O point as the origin, record the theoretical coordinates (x, y) and actual coordinates (x', y') of the point, the positioning deviation of X1 direction is Δx = x'-x, the relationship between the positioning deviation of X1 direction and the theoretical movement distance is recorded as Δx = f(x), the positioning deviation of Y1 direction is Δy = y'-y, the relationship between the positioning deviation of Y1 direction and the theoretical movement distance is recorded as Δy = h(y);

[0033] 6) Repeat step 5) several times, see Figure 2 , fit several Δx = f(x) to obtain the fitting curve equation of X1 direction as Δx = kx, fit several Δy = h(y) to obtain the fitting curve equation of Y1 direction as Δy = dy, the coefficients k and d are the deviation compensation parameters of the joint movement of the robot in X1 direction and Y1 direction respectively, and the user adjusts the movement parameters in the robot control program based on the deviation compensation parameters.

[0034] Example 3:

[0035] The main steps of this embodiment are the same as those of example 2, and further, in step 5), a dual-frequency laser interferometer is used to measure the actual movement distance of the robot.

[0036] Example 4:

[0037] The main steps of this embodiment are the same as those of example 2, and further, the structures and sizes of the special positioning conical I and the special positioning conical II are consistent, see Figure 1 , the structure includes a conical structure and a cylindrical structure, the diameter of the large diameter end of the conical structure is consistent with the diameter of the cylindrical structure, and the large diameter end of the conical structure is connected with the end of the cylindrical structure.

Claims

1. A stud position accuracy control method based on offline programming, characterized by, The method comprises the following steps: 1) mounting a robot on an XYZ moving track and fixing the XYZ moving track on a horizontal work platform, wherein the robot is equipped with a stud grabbing device and a welding torch; 2) selecting a coordinate origin on the work platform and placing a tip of a special positioning cone I of the robot on the coordinate origin, wherein the coordinate origin is located at point O of a plane coordinate system O-X1Y1; 3) the robot grabs a special positioning cone II and aligns a tip of the special positioning cone II with the tip of the special positioning cone I; 4) the robot controls the welding torch to rotate 360° around the special positioning cone II, and keeps the tip of the special positioning cone II aligned with the tip of the special positioning cone I during the rotation of the welding torch, so as to eliminate the movement deviation of the XYZ moving track; 5) controlling the robot to move to different points on the XYZ moving track, measuring the actual movement distance of the robot, recording the theoretical coordinates (x, y) and actual coordinates (x', y') of the points with O as the origin, the positioning deviation in the X1 direction is Δx = x'-x, and the relationship between the positioning deviation in the X1 direction and the theoretical movement distance is Δx = f(x); the positioning deviation in the Y1 direction is Δy = y'-y, and the relationship between the positioning deviation in the Y1 direction and the theoretical movement distance is Δy = h(y); 6) repeating step 5) several times, fitting the several Δx = f(x) to obtain the fitting curve equation of the X1 direction as Δx = kx, fitting the several Δy = h(y) to obtain the fitting curve equation of the Y1 direction as Δy = dy, the coefficients k and d are the deviation compensation parameters of the joint movement of the robot in the X1 direction and the Y1 direction, respectively, and the user adjusts the movement parameters in the robot control program based on the deviation compensation parameters; In step 5), a double-frequency laser interferometer is used to measure the actual movement distance of the robot.

2. The stud position accuracy control method based on offline programming according to claim 1, characterized in that: The special positioning cone I and the special positioning cone II are consistent in structure and size, the structure comprises a conical body structure and a cylindrical structure, the diameter of the large-diameter end of the conical body structure is consistent with the diameter of the cylindrical structure, and the large-diameter end of the conical body structure is connected with the end of the cylindrical structure.

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