CN111702380A - A welding robot welding process control method - Google Patents

Abstract

The invention discloses a welding process control method of a welding robot. The method uses the SolidWorks three-dimensional software secondary development technology to traverse all the welding seams to be welded on the workpiece, and establishes each welding seam on the robot welding seam according to the traversed welding seam data. After the position and posture of the end of the point, the inverse solution operation of the robot is performed to obtain the joint angle data of each point on the robot welding seam, and these joint angle data are used as the parameters of the robot control command to generate the welding program to control the work of the robot. When the method is used for offline programming of the welding robot, the robot welds a workpiece with multiple welding seams, and all the welding programs are automatically generated, and there is no need to operate each welding seam one by one, which is efficient and convenient.

Description

A welding robot welding process control method

technical field

The invention relates to an offline programming method for a welding robot, in particular to a welding process control method for a welding robot.

Background technique

The method of offline programming of welding robot is to make the preparation of robot welding program, the acquisition of the coordinate position of the welding seam track, and the debugging of the program to be completed independently on a computer, without the participation of the robot itself. The offline programming software is mainly in text mode. The programmer needs to be familiar with all the command system and syntax of the robot, and also know how to determine the spatial position coordinates of the welding seam trajectory. Therefore, the programming work is not easy and time-saving. With the development of computer 3D graphics technology, most of today's robot offline programming systems can run in a 3D graphics environment. To obtain the coordinate position of the weld track, the "virtual teaching" method can usually be used, and the mouse can easily click in the 3D virtual environment. The spatial coordinates of the point can be obtained from the welding part of the workpiece, and then the robot program is automatically generated and downloaded to the robot control system. This greatly improves the programming efficiency of the robot. However, when the robot is welding, for the welding of a complex workpiece, there is more than one weld on the workpiece. Using the traditional offline programming method requires manual clicking on each weld, which is time-consuming and labor-intensive.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the shortcomings of the prior art, and to provide a welding process control method for a welding robot with high efficiency, reliability and visual results.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A welding process control method for a welding robot, comprising the following steps:

Step 1. Use SolidWorks 3D software to open the 3D model of the workpiece to be welded and add the weld to be welded on the 3D model of the workpiece, create a new assembly model in the SolidWorks 3D software and put the welding robot and the 3D model of the workpiece to be welded Import the assembly model, and adjust the position of the robot relative to the workpiece in the assembly model according to the actual usage;

Step 2. Use the C# programming language to carry out secondary development of SolidWorks. The specific process is as follows:

Traverse all welds on the workpiece in the assembly model to obtain the weld curve of the weld; read the data of all welds on the workpiece, the data of each weld includes the start and end coordinates of the weld curve, the location of the weld The coordinates of any point between the start and end points of the seam curve, the length of the seam curve S, the type of the seam, and the unit normal vector of the two intersecting surfaces that intersect to form the seam curve;

Step 3: Calculate the three-dimensional coordinates of all discrete points on the weld curve. The specific steps are:

The first step is to discretize the weld curve into multiple points, and make the length of the weld curve between every two adjacent discrete points on the weld curve to be L, and the number of discrete points N = the length of the weld curve S/L;

In the second step, if the type of the weld curve is straight line, use the start and end coordinates of the weld curve to list the spatial parameter equation of the weld curve as (X,Y,Z)=(x(t),y( t), z(t)), where 0≤t≤1, (X, Y, Z) represents the coordinates of any point on the curve, t is the independent variable of the parametric equation, x(t), y(t), z(t) are three coordinate functions with t as the independent variable, X=x(t), Y=y(t), Z=z(t), and the coordinates of the point on the line are calculated according to t (X ,Y,Z);

If the type of the weld curve is arc, use the start point coordinates, end point coordinates, and coordinates of any point between the start point and end point of the weld curve to list the spatial parameter equation of the weld curve as (X, Y , Z)=(x(t), y(t), z(t)), where 0≤t≤1, (X, Y, Z) represents the coordinates of any point on the curve, t is the self-definition of the parametric equation Variables, x(t), y(t), z(t) are three coordinate functions with t as the independent variable, X=x(t), Y=y(t), Z=z(t), Calculate the coordinates (X, Y, Z) of the point on the arc according to t, and calculate the coordinates of the center of the arc as (Xc, Yc, Zc);

The third step is to make the independent variable t=n/N of the spatial parameter equation of the weld curve when finding the three-dimensional coordinates of the nth discrete point, and then substitute t into the spatial parameter equation of the weld curve to calculate the discrete point’s Three-dimensional coordinates (Xn, Yn, Zn), and calculate the three-dimensional coordinates of all discrete points, 1≤n≤N;

Step 4. If the type of the weld curve is straight line, the straight line weld is formed by the intersection of two planes, and the two intersecting surfaces are recorded as A and B, then the welding torch of each discrete point on the straight weld is welded. The axial direction is the sum of the unit normal vectors of the A and B surfaces;

If the type of the weld curve is arc, the arc weld is formed by the intersection of the plane and the cylindrical surface, the weld curve of the arc weld is on the cylindrical surface, and the normal vector of each discrete point on the cylindrical surface is equal to The coordinates of the discrete point (Xn, Yn, Zn) are subtracted from the coordinates of the center of the arc (Xc, Yc, Zc), and then the normal vector of the cylindrical surface at the discrete point is normalized to obtain the cylindrical surface at the discrete point. unit normal vector, the axial direction of the welding torch during welding of each discrete point on the arc weld is the sum of the unit normal vector of the intersecting plane and the unit normal vector of the cylindrical surface at this point;

Step 5. Use the method of step 4 to calculate the axial direction of the welding torch during welding of all discrete points on the weld curve, and use this axial direction as the attitude of the welding torch during welding;

Step 6. Enter the three-dimensional coordinates of the discrete points on the welding seam and the attitude of the welding torch in the robot toolbox module in the MATLAB software to perform the inverse solution operation of the robot, and calculate the rotation angle of each joint when the robot welds the point, and then use this The method calculates the rotation angle of each joint of the robot during the welding of the remaining discrete points on the weld, and finally records the rotation angle data of each joint of the robot when each point of the weld is welded;

Step 7. Repeat steps 3-6 to perform the operation of the next weld curve, until all discrete points of each weld curve are calculated and the data of the rotation angles of each joint of the robot when welding is performed;

Step 8. Use the rotation angle data of each joint of the robot when the robot welds a discrete point obtained in step 7 as the parameter of the joint motion instruction to generate a joint motion instruction that controls the robot to move to this point, and generate according to the order calculated by these discrete points. The joint motion instructions of all discrete points, and all the joint motion instructions generate the robot program when the welding robot welds each weld.

Compared with the prior art, the present invention has the following beneficial effects:

The method of the invention can traverse all the welding seams required to be welded on the workpiece and automatically generate the welding program of each welding seam through the three-dimensional software secondary development technology, which is used to solve the offline programming problem involved in the welding robot. Simple, efficient and reliable method with visual results.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

A welding process control method for a welding robot of the present invention includes the following steps:

Step 1. Use SolidWorks 3D software to open the 3D model of the workpiece to be welded and add the weld to be welded on the 3D model of the workpiece. Create a new assembly model in SolidWorks 3D software and import the 3D model of the welding robot and the workpiece to be welded into the assembly model, and adjust the position of the robot relative to the workpiece in the assembly model according to the actual usage.

Step 2. Use the C# programming language to carry out secondary development of SolidWorks. The specific process is as follows:

Traverse all welds on the workpiece in the assembly model to obtain the weld curve of the weld. Read the data of all welds on the workpiece. The data of each weld includes the start and end coordinates of the weld curve, the coordinates of any point between the start and end points of the weld curve, the length of the weld curve S, the The type of seam and the unit normal vector of the two intersecting faces that intersect to form the weld curve.

Step 3: Calculate the three-dimensional coordinates of all discrete points on the weld curve. The specific steps are:

The first step is to discretize the weld curve into multiple points, and make the length of the weld curve between every two adjacent discrete points on the weld curve to be L, and the number of discrete points N = the length of the weld curve S/L.

In the second step, the weld curve is divided into two types, one is a straight line, the other is an arc, two points establish a straight line, and three non-collinear points establish a circle.

If the type of weld curve is straight line, use the start and end coordinates of the weld curve to list the spatial parameter equation of the weld curve as (X,Y,Z)=(x(t),y(t),z (t)), where 0≤t≤1, (X, Y, Z) represents the coordinates of any point on the curve, t is the independent variable of the parametric equation, x(t), y(t), z(t) They are three coordinate functions with t as the independent variable, X=x(t), Y=y(t), Z=z(t). According to t, the coordinates of the point on the line can be calculated (X, Y, Z);

If the type of the weld curve is arc, use the start point coordinates, end point coordinates, and coordinates of any point between the start point and end point of the weld curve to list the spatial parameter equation of the weld curve as (X, Y , Z)=(x(t), y(t), z(t)), where 0≤t≤1, (X,Y,Z) represents the coordinates of any point on the curve, t is the self-definition of the parametric equation Variables, x(t), y(t), z(t) are three coordinate functions with t as the independent variable, X=x(t), Y=y(t), Z=z(t), According to t, the coordinates (X, Y, Z) of the point on the arc can be calculated. At the same time, the center coordinates of the arc are calculated as (X _c , Yc, Zc).

The third step is to make the independent variable t=n/N of the spatial parameter equation of the weld curve when finding the three-dimensional coordinates of the nth (1≤n≤N) discrete point, and then substitute t into the spatial parameter of the weld curve The equation calculates the three-dimensional coordinates (Xn, Yn, Zn) of the discrete point, and calculates the three-dimensional coordinates of all discrete points.

Step 4. Record the two intersecting surfaces that intersect to form the weld curve as surface A and surface B. When the welding torch welds a discrete point on the weld, draw a first straight line through the discrete point on the A surface and draw a straight line. Make this line perpendicular to face B, and make a second straight line through the discrete point on face B and make this straight line perpendicular to face A. These two straight lines intersect at the discrete point. When the welding torch is welding the discrete point The angle bisector of the intersection of the first line and the second line can ensure that the welding torch does not interfere with the workpiece, so the axial direction of the welding torch should be the same as the direction of the above-mentioned angle bisector, and the direction is represented by a vector. The vector of the angle bisector is equal to the sum of the unit vectors of the above two straight lines. The straight line on face A and perpendicular to face B is the normal vector of face B at the discrete point, and the straight line on face B and perpendicular to face A is The normal vector of surface A at the discrete point, the vector of the above-mentioned angle bisector is the sum of the unit normal vectors of the two intersecting surfaces that intersect to form the weld at the discrete point, so the axial direction of the welding torch is the intersection to form the weld The sum of the unit normal vectors of the two intersecting faces of the seam at this discrete point.

If the type of weld curve is straight, the straight weld is formed by the intersection of two planes, and the unit normal vector of the plane remains unchanged at each point on the face, then the axis of the welding torch when welding each discrete point on the straight weld The direction is the sum of the unit normal vectors of the A and B faces.

If the type of the weld curve is arc, the arc weld is formed by the intersection of the plane and the cylindrical surface, and the weld curve of the arc weld is on the cylindrical surface, so the arc weld curve on the arc weld is formed. Discrete points are also on the cylindrical surface. The normal vectors of different points on the cylindrical surface are different and need to be calculated separately. The normal vector of each discrete point on the cylindrical surface is equal to the coordinates of the discrete point (Xn, Yn, Zn) minus the coordinates of the center of the arc (Xc, Yc ,Zc), and then unit the normal vector of the cylindrical surface at the discrete point to obtain the unit normal vector of the cylindrical surface at the discrete point, then the axial direction of the welding torch when welding each discrete point on the arc weld is the intersection The sum of the unit normal of the plane and the unit normal of the cylinder at that point.

Step 5: Use the method of step 4 to calculate the axial direction of the welding torch during welding of all discrete points on the weld curve, and use this axial direction as the attitude of the welding torch during welding.

Step 6. Enter the three-dimensional coordinates of the discrete points on the welding seam and the attitude of the welding torch in the robot toolbox module in the MATLAB software to perform the inverse solution operation of the robot, and calculate the rotation angle of each joint when the robot welds the point, and then use this The method calculates the rotation angle of each joint of the robot during the welding of the remaining discrete points on the weld, and finally records the rotation angle data of each joint of the robot when each point of the weld is welded.

Step 7: Repeat steps 3-6 to perform the calculation of the next weld curve, until all discrete points of each weld curve are calculated and the rotation angle data of each joint of the robot when welding is performed.

Step 8. There are joint motion instructions in the industrial robot program to control the motion of the robot. The parameters of the joint motion instructions are the rotation angle data of each joint of the robot. Each joint motion instruction will make the rotation angle of each joint of the robot rotate from the current rotation angle to the instruction. corner. Use the rotation angle data of each joint of the robot when the robot welds a discrete point obtained in step 7 as the parameter of the joint motion instruction to generate a joint motion instruction to control the robot to move to this point, and generate all discrete points in the order calculated by these discrete points. All the joint motion instructions generate the robot program when the welding robot welds each weld.

Claims (1)

1. A welding process control method of a welding robot is characterized by comprising the following steps:

step one, opening a three-dimensional model of a workpiece to be welded by using SolidWorks three-dimensional software, adding a welding seam to be welded on the three-dimensional model of the workpiece, newly building an assembly body model in the SolidWorks three-dimensional software, introducing a welding robot and the three-dimensional model of the workpiece to be welded into the assembly body model, and adjusting the position of the robot relative to the workpiece in the assembly body model according to the actual use condition;

step two, carrying out secondary development on the SolidWorks by using a C # programming language, wherein the specific process is as follows:

traversing all welding seams on the workpiece in the assembling body model to obtain a welding seam curve of the welding seams; reading data of all welding seams on a workpiece, wherein the data of each welding seam comprises coordinates of a starting point and an end point of a welding seam curve, coordinates of any point between the starting point and the end point of the welding seam curve, the length S of the welding seam curve, the type of the welding seam and a unit normal vector of two intersecting surfaces intersecting to form the welding seam curve;

step three, calculating three-dimensional coordinates of all discrete points on the welding seam curve, and specifically comprising the following steps:

the method comprises the following steps that firstly, a weld curve is discretized into a plurality of points, the length of the weld curve between every two adjacent discretized points on the weld curve is L, and the number N of the discretized points is equal to the length S/L of the weld curve;

secondly, if the type of the welding seam curve is a straight line, using the coordinates of the starting point and the coordinates of the ending point of the welding seam curve to list the space parameter equation of the welding seam curve as (X, Y, Z) < X (t), Y (t), Z (t)), wherein t is more than or equal to 0 and less than or equal to 1, (X, Y, Z) represents the coordinates of any point on the curve, t is the independent variable of the parameter equation, X (t), Y (t), Z (t) are three coordinate functions with t as the independent variable respectively, X ═ X (t), Y ═ Y (t), Z ═ Z (t), and calculating the coordinates (X, Y, Z) of the point on the straight line according to t;

if the type of the welding seam curve is an arc, using coordinates of a starting point, coordinates of an end point and coordinates of any point between the starting point and the end point of the welding seam curve to list spatial parameter equations (X, Y, Z) < X (t), Y (t), Z (t)), wherein 0 < t < 1, (X, Y, Z) represents coordinates of any point on the curve, t is an independent variable of the parameter equation, X (t), Y (t), Z (t) are three coordinate functions with t as an independent variable, respectively, X < X > (t), Y < Y (t), and Z < t), calculating coordinates (X, Y, Z) of the point on the arc line according to t, and calculating coordinates (Xc, Yc, Zc) of the center of the arc;

thirdly, when the three-dimensional coordinate of the nth discrete point is obtained, enabling the independent variable t of the space parameter equation of the welding line curve to be N/N, substituting t into the space parameter equation of the welding line curve to calculate the three-dimensional coordinate (Xn, Yn and Zn) of the discrete point, and calculating the three-dimensional coordinate of all the discrete points, wherein N is more than or equal to 1 and less than or equal to N;

if the type of the welding seam curve is a straight line, the straight line welding seam is formed by intersecting two planes, and the two intersecting surfaces are marked as an A surface and a B surface, the axial direction of the welding gun is the sum of unit normal vectors of the A surface and the B surface when each discrete point on the straight line welding seam is welded;

if the type of the welding line curve is an arc, the arc welding line is formed by intersecting a plane and a cylindrical surface, the welding line curve of the arc welding line is on the cylindrical surface, the normal vector of each discrete point on the cylindrical surface is equal to the coordinate (Xn, Yn, Zn) of the discrete point minus the center coordinate (Xc, Yc, Zc) of the arc, and then the normal vector of the cylindrical surface at the discrete point is unitized to obtain the unit normal vector of the cylindrical surface at the discrete point, so that the axial direction of the welding gun during welding of each discrete point on the arc welding line is the sum of the unit normal vector of the intersected plane and the unit normal vector of the cylindrical surface at the point;

step five, calculating the axial direction of the welding gun during welding of all discrete points on the welding seam curve by adopting a four-way method, and taking the axial direction as the posture of the welding gun during welding;

inputting the three-dimensional coordinates of discrete points on the welding seam and the posture of the welding gun at the moment into a robot tool box module in MATLAB software to perform inverse solution operation of the robot, calculating the rotating angle of each joint when the robot welds the points, calculating the rotating angle of each joint of the robot when the remaining discrete points on the welding seam are welded by using the method, and finally recording the rotating angle data of each joint of the robot when each point on the welding seam is welded;

step seven, repeating the step three-six to calculate the next welding line curve until the corner data of each joint of the robot when all discrete points of each welding line curve are welded are calculated;

and step eight, using the corner data of each joint of the robot obtained in the step seven when the robot welds a certain discrete point as the parameters of the joint movement command to generate a joint movement command for controlling the robot to move to the point, generating the joint movement commands of all the discrete points according to the sequence calculated by the discrete points, and generating a robot program when the welding robot welds each welding line by all the joint movement commands.